Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: Building a dairy herd
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Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00026797/00001
 Material Information
Title: Building a dairy herd
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 36 p. : ill. ; 23 cm.
Language: English
Creator: Arnold, P. T. Dix, 1902-
Becker, R. B ( Raymond Brown ), 1892-1989
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1956
Copyright Date: 1956
 Subjects
Subject: Dairy cattle -- Breeding   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
Statement of Responsibility: P.T. Dix Arnold and R.B. Becker.
General Note: Cover title.
 Record Information
Bibliographic ID: UF00026797
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - AEN7067
oclc - 18287218
alephbibnum - 000926395

Full Text





HISTORIC NOTE



The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






7(

_-Bulletin 576 i June 1956


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
JOSEPH R. BECKENBACH, Director
GAINESVILLE, FLORIDA








BUILDING A DAIRY HERD
,D. r*

P. T. DIX ARNOLD and R. B. BECKER
z




r)

Fig. 1.-Bull C proved desirable on sampling, and completed his useful
lifetime in the station herd.

















CONTENTS
Page

INTRODUCTION ...- ......- ....--- .. ........S......... ..........--... ........ 3

METHODS OF INVESTIGATION .--....-----.. --.......... --.---.. --- -- -----............. 4

BREEDING RESULTS WITH BULLS -...........----------...------...---..--.. 5
Proofs of Herd Sires .--..........---------------------........... --- ...... 5
Proportion of Desirable Dairy Bulls .................... ----- ......------ 9
Useful Life of Dairy Bulls ........ --------........ .... .....----.--. 11
Causes of Losses of Desirable Bulls ...................................--- ..... --...... 12

BREEDING RESULTS WITH COWS .......................---------...----..... 13
What Gives Value to a Dairy Cow? -...--....--...- ........ ..-----....---- 13
Building a Herd from Foundation Cows ...----........--------.......-...- 14
Useful Life of Dairy Cows ...........----------..........-----....- 18
Records of Individual Cows ...-- --------- ------.............---...-...----18
Brood Cow Families .------....... ------............ -....... -----.--- 21
Brood Cows through Generations .-.....................-------- ----------..... 24

ACCOMPLISHMENT FROM SELECTIVE BREEDING .------...............-------... ..... 25

BREEDING EFFICIENCY AND REPRODUCTION IN HERD BUILDING ---.............. 25
Breeding Efficiency ............... ....... ................. -....- .......... 25
Age Affects Breeding Efficiency ....-------............. .....----------.. 26
Selection of Calves to be Raised ..--................------ ------------.............. 28
Heifers that Survive .................... -- --..................-.......-.. .. .. --- 28
Age at First Calving and Living Calves Dropped ......................... ..--- 30
Calving Intervals ....- --- ---...........-------.... ...... ----..........-- 30
Calving Intervals Affect Average Daily Milk Yields .. ....--......---- 33
Maintaining Numbers in the Dairy Herd ...............- --------.. ----....--. .. 35

DISCUSSION AND CONCLUSIONS ...------........--- --- .....- ----------- 36

ACKNOWLEDGMENTS ..........------------------...........-... .......--------- 36









BUILDING A DAIRY HERD

P. T. DIx ARNOLD and R. B. BECKER
Florida Agricultural Experiment Station
Gainesville, Florida

INTRODUCTION
Under present specialization in agriculture, unit production
of foodstuffs must be economical. Dairy cows should produce
well above the average for cows generally in the United States
to pay their way in commercial dairies. Continued selection
and multiplication among cows of above average milking ability
are required in order to maintain herds at profitable levels of
production. This calls for continued and persistent culling of
poor and mediocre cows.
Production records of dairy cows need to be kept continuously,
beginning with the first lactation. Cows in varying numbers
need to be culled for low production following the first or second
lactation. Careful elimination of these low producers and their
progeny reduces the proportion of heifer calves raised for re-
placements from low-producing cows. Good commercial cows
then represent selected groups above the general average in
producing ability. The various factors in breeding and selec-
tion of cows above this general average will be discussed in
this publication. This investigation was based largely on com-
plete records from a dairy herd in which the plan was to retain
every heifer calf. Results were measured by records of produc-
tion, reproduction and transmitting ability.
With about 22,000,000 dairy cows in the United States, about
9,400,000 heifer calves1 are dropped annually. Average losses
of heifer calves and heifers from all causes before first calving
amount to 30 to 35 percent, based on experience of several ex-
periment stations. Over 5,540,000 heifers must survive and
come into lactation as replacements to maintain the numbers
of milking cows in dairy herds over the country. An industry of
this magnitude justifies attention to many problems involved
in maintenance of dairy herds. Several experiment stations
and the United States Department of Agriculture have studied
parts of this problem. Increasing human population and the
trend toward increased per capital consumption of many dairy
products require that cow numbers and producing ability be in-
creased, to meet national needs.
SBased on a 410-day average calving interval, and a ratio of 48 heifers
to 52 male calves.







4 Florida Agricultural Experiment Stations

Breeding, feeding and management all play important roles
and are interdependent. Breeding better dairy cows, therefore,
requires continued attention to selection and culling based on de-
pendable records.
Selection of bulls should be more critical than selection of
cows. Even with current methods, about one-third of the dairy
bulls transmit lower production than the selected cows with
which they are mated.

METHODS OF INVESTIGATION
It is necessary to keep dairy cattle under relatively uniform
conditions over a long period in order to evaluate fairly the
results of a breeding program.
The dairy herd at the Florida Agricultural Experiment Sta-
tion was handled under comparatively uniform conditions be-
tween 1929 and 1947. All heifer calves except two were re-
tained. Every animal that calved was allowed to complete at
least one full lactation, regardless of producing ability. The
cows grazed on pastures of mixed grasses mainly, with some
corn or sorghum silage in relatively liberal amounts. Limited
amounts of legume hay (alfalfa, Alyce clover, or cowpea) were
used with the better producing cows when grazing was limited.
Mixed concentrates containing about 17 percent of total crude
protein were fed in proportion to milk and butterfat produc-
tion. Mineral matter was incorporated in the concentrates. This
consisted of 1 percent of common salt and 2 percent of steamed
bonemeal. Since January 21, 1938, marble dust ("Kalsite")
replaced one-half of the steamed bonemeal. When bonemeal
was unavailable in the area during World War II, the percent
of marble dust was increased to 1.5 percent. Additional mineral
matter was supplied in mineral boxes containing (a) loose salt,
(b) steamed bonemeal and, after 1931, (c) an iron-copper sup-
plement to which cobalt sulfate was added in 1937 2.
Every cow was tested under rules of official testing during the
first lactation, and the majority of them again at about five
years of age. Complete milk weights and monthly butterfat
tests were kept. All lactations, on two milkings daily, were
used in comparing the production of daughters with that of
their dams. Complete breeding and calving records were kept.
The herd was accredited as tuberculosis-free and tested reg-
ularly for brucellosis.

Formula of this supplement is: common salt, 100 lbs.; red oxide of
iron, 25 Ibs.; copper sulfate, 1 pound; cobalt sulfate, 1 ounce.







Building A Dairy Herd 5

Several points were considered when selecting young bulls
to be herd sires. These included production of ancestry, family
bloodlines and general dairy conformation of the individuals and
of related animals. Size and capacity of cows in the family from
which the bull was selected were taken into account. Health
tests were required.
To secure sufficient records concerning transmitting ability
of dairy bulls, recourse was taken to records assembled by the
Bureau of Dairy Industry on bulls whose daughters were tested
in Dairy Herd Improvement Associations throughout the United
States.
BREEDING RESULTS WITH BULLS
PROOFS OF HERD SIRES
The cost of raising heifers is considerable, and the chances
are variable that they may prove profitable. Hence it is a sound
practice to sample a junior sire before placing him in heavy
service. Whenever possible, each bull was bred to 20 to 25 cows
in expectation of obtaining 10 heifer calves. This number of
unselected daughters has been considered an adequate sample.
Thereafter, the bull was either retired from service temporarily
or used lightly until his daughters were in milk and provided
a measure of his transmitting ability.
A bull usually is 12 months old before time of first use. The
oldest heifer calves may be dropped when he is about 20 months
old. These heifers freshen in another two years, and require
at least an additional 305 days to complete the first lactation.
The sire would be nearly five years old, at the very youngest,
by the time 10 daughters could furnish a measure of his trans-
mitting ability when used in natural service.
The desirability of restricting use of a young bull until his
value as a transmitter is known is borne out by several typical
cases.
Bull A (Table 1) was bred to 23 cows resulting in 13 heifers
which were raised and completed at least one lactation. The
first heifer to finish a lactation produced 7,632 pounds milk and
412 pounds butterfat, which was an increase of over 1,750 pounds
of milk above the production of her dam. However, the 13
daughters of this bull averaged only 4,531 pounds milk and 230
pounds butterfat; they were from dams which averaged 5,092
pounds milk and 262 pounds butterfat. Thus Bull A was not
placed in heavy service, even though his first daughter was out-
standing.












TABLE 1.-AVERAGE YEARLY (365-DAY) PRODUCTION OF DAUGHTERS OF JERSEY BULLS AS COMPARED WITH THAT OF THEIR
DAMS AT CORRESPONDING AGES *.
I F I
SNumber of I Daughters Dams Percentage of Daughters
Sire Daughter- Lactations __Better than Dams in
I Dam Pairs I I Milk I Test Fat Milk I Test Fat I Milk i Test I Fat
I __ I Dau. Dam Lbs. I % Lbs. Lbs. I % Lbs. % _% _%1

A 13 52 38 4,531 4.96 230 5,092 5.12 262 46 38 46

B 8 26 22 3,123 5.28 168 6,008 5.06 302 13 75 13

C 67 170 158 6,374 5.03 321 5,412 5.28 286 70 24 58

D 32 53 48 6,286 5.09 320 6,180 5.02 310 44 59 53
I I'
E 17 24 24 6,445 5.07 327 5,767 5.17 298 53 35 47

F 5 10 10 4,806 4.97 239 6,610 5.27 349 0 20 0 0
I I.
G 13 18 17 6,214 5.10 317 4,781 5.28 252 77 31 77

These include all normal lactations up to 365 days in length completed by daughters and dams up to time of tabulation. Since these bulls
were used somewhat in sequence, a larger proportion of the records for bulls D, E, F and G are for the first and second lactations mainly.







Building A Dairy Herd 7

Bull B was bred to 25 cows and sired eight daughters that
freshened. These eight daughters averaged 3,123 pounds milk
and 168 pounds butterfat during their first lactations, ranging
from 1,416 to 5,082 pounds of milk. The dams of these cows
averaged 6,008 pounds milk and 302 pounds butterfat. Bull B
had been selected because his dam was outstanding in conforma-
tion and had two official yearly records of 747 and 761 pounds
of butterfat. She had no daughter in milk before Bull B was
purchased. His sire was a consistent show winner as a young
bull but was too young to be proved for transmitting ability at
the time of selecting Bull B. The udders of Bull B's daughters
were found to contain a relatively small amount of secretary
tissue and more than the usual amount of fatty tissue. He was
culled for transmitting low production, despite the fact that
his daughters had high butterfat tests.
Bull C (Fig. 1) had a large frame and good capacity. He trans-
mitted size, capacity, dairy temperament and excellent udder
texture to his daughters. They appeared rough as two year
olds, improving in general appearance as they matured. His
first daughters were steady, persistent milkers, and most of them
yielded more milk and butterfat than did their dams, despite
a slight reduction in butterfat percentage. He was used the
remainder of his natural lifetime, siring 67 daughters, 70 per-
cent of which produced more milk than their dams.
The first daughters of Bull D yielded only slightly less milk
than their dams, but the milk tested sufficiently higher that the
butterfat yields were an increase. Furthermore, these daugh-
ters milked at a satisfactory level. After being proved, the bull
was returned to regular use during the remainder of his natural
lifetime. The lifetime records of his daughters averaged 6,286
pounds of milk and 320 pounds of butterfat, while their dams
yielded 6,180 pounds of milk and 310 pounds of butterfat. Al-
though only 44 percent of his daughters were higher milkers
than their dams, 53 percent yielded more butterfat.
Bull E lived only a short while after he had been found to
transmit satisfactorily. He died from a natural cause.
Bull F's low transmitting ability was suspected when his first
daughter freshened. When four daughters had freshened, and
produced poorly, he was discarded. None of his five daughters
milked as well as their dams.
Bull G produced daughters of less size, dairy character and
strength of udder attachments, even though they yielded con-









00

10







St

0



W 4
c I




0


0 Dam-daughter pairs
Fig. 2.-An arrow graph comparing average lactations of daughters of Bull C with those of their respective
dams. These 61 daughters had 199 completed milk records, while the dams had 357 milk records to this date. Base of
each arrow indicates average milk yield of the dam; point indicates her respective daughter's (or daughters' from same
dam) average lactation in pounds of milk.







Building A Dairy Herd 9

siderably more milk and pounds of butterfat in the first lacta-
tions than did their dams.
Average production records of daughters do not give a true
measure of a bull's transmitting ability. A more accurate
analysis requires a comparison of each daughter with her dam
in milk yield, butterfat percentage, and pounds of butterfat.
This is seen most readily from arrow charts. An arrow chart
in Figure 2 compares the average milk yields of Bull C's daught-
ers with those of their dams.
Bull C seldom increased production of daughters out of dams
exceeding 7,000 pounds of milk. However, there was a sub-
stantial increase in his daughters from lower producing dams.
As expected, some variations occurred within 12 sets of full
sisters. These records are shown in Figure 2. Dams of six
daughters did not complete their first lactations normally, hence
neither they nor their daughters were included in Figure 2.
Dams ranged in average yearly production between 2,279 and
7,955 pounds of milk. Their daughters by bull C ranged be-
tween 3,809 and 10,343 pounds, with only six daughters yielding
less than 5,000 pounds of milk. Twenty-one daughters exceeded
6,000 pounds of milk yearly. An analysis of milk production
of daughters as compared with dams showed:


I Daughters
Milk Production of Dams I
Decrease ] No Change Increase
Below 5,000 pounds ............ 0 0 I 20
5,000 to 6,000 pounds .......... 4 0 | 16
Above 6,000 pounds ..-........ 12 2 7
SI _I
Total daughters ................... 16 2 43

PROPORTION OF DESIRABLE DAIRY BULLS
What proportion of dairy bulls prove to be satisfactory? This
varies considerably, depending upon the bull's transmitting abil-
ity, the producing ability of the cows with which he is mated,
and upon feed, care and management. An analysis of this
information requires data on more bulls than are obtainable
from a single herd.
The Bureau of Dairy Industry analyzed the production records
of cows in Dairy Herd Improvement Associations over the
country, as submitted by the Agricultural Extension Service of








10 Florida Agricultural Experiment Stations

the respective states. From these records, bulls are "proved"
by comparing production records of five or more daughters with
that of their respective dams. Data in Agriculture Handbook
No. 7 on 4,289 dairy bulls have been re-tabulated in Table 2 ac-
cording to average butterfat production of the dams and daugh-
ters, and whether the daughters increased or decreased in yield.
In this analysis, it was considered that there was almost no
change when the average butterfat production of the daughters
was within about 10 pounds of that of their dams. Data were
sorted according to average butterfat yields of each group of
dams. The average fat yields of dams ranged from less than 250
pounds to over 575 pounds of butterfat. These records represent
production under existing practices of feeding and management
on many farms widely distributed over the United States. In
many instances, the figures may not show a true picture of in-
herited capacity to produce, but they do indicate an important
trend applicable to breeding practices.

TABLE 2.-INFLUENCE OF 4,289 BULLS OF FIVE DAIRY BREEDS ON BUTTERFAT
PRODUCTION OF DAUGHTERS AS COMPARED WITH THEIR DAMSI*.
Range I
of Average Influence of Bulls on Daughter's Fat Production
Fat of Dams Increased Maintained** I Decreased
pounds number I percent number percent I number I percent
575 and above 6 100
550 575 .... 5 29 1 6 11 65
525 550 ..- 6 21 4 14 19 I 65
500 525 ... 27 35 6 8 44 | 57
475 500 .... 59 32 17 9 109 59
450 475 ... 104 30 68 20 172 50
425 450 .... 195 36 110 20 243 44
400 425 .... 284 39 126 18 307 43
375 400 .... 342 43 141 18 313 39
350 375 .... 320 47 149 22 216 31
325 350 .. 279 56 73 14 148 | 30
300 325 .... 124 56 50 22 50 12
275 300 .... 79 72 13 12 18 16
250 275 .... 24 69 5 14 6 | 17
Below 250 .... 10 63 4 25 2 12

Total .-........ 1,858 767 1,664
Percentage -. 43 18 39
Analyzed from records reported in U.S.D.A. Agriculture Handbook No. 7, 1950.
"** A bull was considered to maintain production if records of daughters and dams varied
10 pounds or less in butterfat.

Of 4,289 bulls analyzed, 43 percent (1,858) had daughters that
produced more butterfat on the average than their dams.
Daughters of 18 percent of the bulls produced within 10 pounds
of their dams, while the daughters of 39 percent failed to equal










Building A Dairy Herd 11

their dams' records.' Further study of Table 2 shows that 72
percent of the bulls increased butterfat production of daughters
from dams producing 275 to 300 pounds of butterfat. However,
the percent of bulls that increased daughters' production, when
mated to cows averaging 400, 500, 550 and 575 pounds, decreased
to 39, 35, 29 and 0 percent, respectively.
As cows increase in production, fewer bulls will maintain or
increase the production of daughters as compared with their
dams. This emphasizes the need for greater care in selection
and proving of bulls, especially as production of cows increases.

USEFUL LIFE OF DAIRY BULLS
After a bull has been proved desirable, how long may he be
expected to remain useful?

TABLE 3.-AVERAGE USEFUL LIFE SPAN AND ANTICIPATED USEFULNESS OF
DAIRY BULLS IN NATURAL SERVICE AT DIFFERENT AGES *.
(BULLS BORN BEFORE 1937.)
I Average Age
Age of Number I at Last Effective Av. Anticipated
Group of Bulls** I Service I Useful Life
years I years I years
5 3,895 10.43 5.43
6 3,670 10.73 4.73
7 3,392 11.08 4.08
8 3,036 11.51 3.51
9 2,617 11.99 2.99
10 2,153 12.53 2.53
11 1,573 13.26 2.26
12 1,084 13.54 1.54
13 641 14.29 1.29
14 319 15.14 1.14
15 131t 16.15 1.15t
16 58t 16.98 0.98t
17 22t 17.86 0.86t
18 8t 18.79 0.79t
19 3 1 19.25 0.25t

Taken from Fla. Agr. Expt. Sta. Bul. 540. 1954.
** These cumulative totals decrease by animals lost during each succeeding year.
t Too few animals for reliance on estimated future usefulness.

Farmers keeping one of five major breeds of dairy cattle in
the United States and Canada answered questions concerning
life span of sires in their herds. The dairy cattle breed associa-
tions and fieldmen cooperated in supplementing many records.
Since a bull must be about five years old before he can be proved
worthy as a transmitter of production, this analysis deals with
animals of that age and older that lived out their natural use-
fulness as breeders. A summary of 3,895 records of Ayrshire,










12 Florida Agricultural Experiment Stations

Brown Swiss, Guernsey, Holstein and Jersey bulls (as taken
from Fla. Agr. Exp. Sta. Bul. 540) is presented in Table 3.
These bulls were successful in producing conceptions to an
average age of 10.43 years, or 5.43 years beyond the fifth birth-
day. At 10 years of age, 2,153 (55 percent) of these bulls were
still in active service, and with an average anticipated life, based
on the records, of 2.53 years. By their fourteenth birthdays
only 319 (8 percent) remained, good for 1.14 more years on the
average. The decrease in numbers was so great each subsequent
year that an estimate of future usefulness would be subject to
considerable question. Three dairy bulls among 3,895 were
effective, however, to an average of 19.25 years.

CAUSES OF LOSSES OF DESIRABLE BULLS
Reasons for losses of dairy bulls from natural service were ob-
tained from the same sources as those discussed previously
(Table 3). More records are included and most of these bulls
were born before 1942. A total of 5,355 records are presented
in Table 4.

TABLE 4.-REASONS FOR DISPOSAL OR CAUSES OF DEATH OF DESIRABLE BULLS
IN NATURAL SERVICE. (BORN BEFORE 1942.)
I I Percent of
Termination of Use I Number I Total
Attributed to: Iof Bulls I Number

Non-infectious causes:
Sterility .................................. 1,538 28.72
Undiagnosed death ................ 606 11.32
Accidents, injuries, etc. .......... 519 9.69
Low fertility, inability ........ 483 9.02
Senility ...................................... 475 8.87
W ire, nails, etc. -...--...........----- .. 282 5.27
Lameness (bad feet and legs) 274 5.12
Digestive diseases --..................111 2.07
Paralysis ........----.....-- ...-........- 75 1.40
Other non-infectious causes .. 141 _2.63
Infectious causes: percent
Lumpy jaw actinomycosiss) .. 192 3.58
Brucellosis ................................ 131 2.45
Tuberculosis, Johne's disease 86 1.61
Pneumonia ................................ 84 1.57
Abscesses and tumors ............ 82 1.53
Trichomoniasis ........................ 79 1.47
Kidney and bladder conditions 54 1.01
Diseases of reproductive tract 45 0.84
Other infectious causes ........ 98 1.83
Total from infectious causes .. I 15.89

Total ...................................... ... 5,355 ___ 100.00







Building A Dairy Herd 13

Owners attributed sterility from various causes as ending the
usefulness of 28.75 percent of these bulls. Low fertility or
inability to serve accounted for 9.02 percent. Undiagnosed
deaths ended the useful life of 11.32 percent. Accidents and
injuries caused 9.69 percent to be slaughtered. Other nonin-
fectious causes are listed in Table 4. The largest number of
losses due to infectious causes was from actinomycosis (lumpy
jaw), brucellosis, tuberculosis and Johne's disease, pneumonia,
and abscesses, in that order. Losses from infections totalled
15.89 percent of the bulls studied.
Knowledge of the natural reasons for bulls going out of service
allows herdsmen to eliminate or reduce the hazards from some
causes, or to obtain timely veterinary service. This may pro-
long the usefulness of valuable animals.

BREEDING RESULTS WITH COWS
WHAT GIVES VALUE TO A DAIRY COW?
The value of a dairy cow depends upon a combination of fac-
tors. Most important is the cow's ability to produce a large
amount of milk and butterfat in proportion to the total amount
of feed she consumes. Lightness of natural fleshing, popularly
called "dairy temperament," indicates that a relatively small
proportion of the total feed intake is needed to maintain the
body.
'The digestive system needs a large capacity to hold much
more feed than is needed for maintenance. The cow should
have a strongly attached udder containing much secretary tissue,
and a hormone make-up essential to persistent production at a
satisfactory rate. She must be healthy and in good physical
condition. Her age and breeding history, number of calves pro-
duced, date of last calving, subsequent service record, and quality
of sire to which she is bred must be satisfactory.
Regular reproduction is essential to maintain milk production.
The cow should have a genetic make-up that will insure trans-
mission of dairy characteristics to her progeny. Too old a cow
may not remain long in a breeding herd. Several investigators
have computed average productive life of dairy cows to be be-
tween four and six years after calving for the first time. These
computations took into account the early culling of undesirable
animals, disease, accidental deaths, sterility and age. Proper
registration and transfer certificates from the breed association
are essential with registered purebred dairy animals.







14 Florida Agricultural Experiment Stations

All these facts help to evaluate a cow. A serious fault in a
single point may eliminate her from further consideration.

BUILDING A HERD FORM FOUNDATION COWS
When a desirable cow has been selected as foundation stock
in a herd, she may contribute considerably to the future herd
because of her desirable female offspring generation after gen-
eration. Many dairy herds have been built from one or a few
fortunate selections of good cows. Yet, a well selected cow may
leave no effect on the herd after a few years because she bears
no female offspring, or because her daughters and granddaugh-
ters lack desirable qualities.
During the 47-year period after the first purebred Jersey cow
was acquired by the Florida Agricultural Experiment Station,
39 Jersey cows were selected and brought into the herd. Several
became the founders of large families. One family has had
181 female progeny in 11 generations. This constituted 32 per-
cent of the herd in 1948. Thus, practically one-third of the
herd descended from one cow in a 37-year period.
Three other cows were represented in the herd in 1948 by
14, 14 and 13 percent of the total, in 35, 26 and 11 years, re-
spectively. Tenure of the respective cow families in the herd
during nearly 50 years is shown in Figure 3.
Reasons for disposal of 425 female offspring from 39 founda-
tion cows fall into six categories: death, low production, non-
breeding, no female offspring, disease or accident, and sale.
These were summarized into the following groups. Twenty-
six percent died young, some being born dead. Culling for low
production accounted for 16 percent. Seventeen percent were
eliminated for nonbreeding. These included sterile heifers,
freemartins and older cows that failed to conceive after num-
erous services. Seven percent of the cows left the herd because
they had no female offspring, yet had lived a usual life span or
beyond.
Cows listed as "sold" went to other dairy herds before 1929
when a policy was adopted to sell no females for dairy purposes.
Reason for this change was to increase the herd for research
purposes, and to study factors concerned with dairy cattle breed-
ing and herd building.
Diseases and accidental deaths accounted for 29 percent of
females leaving the herd. In the 1920's brucellosis was elimi-
nated from the herd. Reaction to the tuberculin test was al-
most no factor in herd losses, and none occurred after the mid-








Building A Dairy Herd 15

1920's. Mastitis caused heavy losses for a period. Poisonous
plants were responsible for a few deaths. Parasites weakened
some calves so much that they were easy prey to pneumonia
and other diseases. Accidents included a broken neck, broken
legs, snake bite, drowning, and poisoning from licking lead paint
containers and empty fertilizer bags.
Present
1901 1911 1921 1931 1941 1950 no.
Cow no.
2 0 0
17 00
18- 0 0
19 0 0
20 00
37. 0 0
38- 24 31.65
59 19 13.67
81- 2 1.44
103 -- 00
104 00
105- 00
106 00
115 00
116 --- 00
117 00
213 10 721
225 19 13.67
236 00
30 00
538- 00
539- 2 L44
540- 00
541- 4 288
581-- 00
582- 3 2.16
802 00
803- -- 00
804- 00
805 2 1.44
806 18 12.95
888- -- 00
889 3 2.16
3-F- 4 2.88
w230 I 0.72
w236 2 1.44
w256. 2 1.44
w260 2 1.44
w269 2 1.44
Fig. 3.-Tenure of cow families in the Station herd between 1901 and 1950.

This analysis of records from the Florida Agricultural Experi-
ment Station and general observations point toward orie con-






TABLE 5.-FOUNDATION COWS AND THEIR DESCENDANTS IN THE FLORIDA AGRICULTURAL EXPERIMENT STATION DAIRY HERD
DURING A 47-YEAR PERIOD.
Entered Generations of Descendants
Foundation Year_____ I
Cow I Herd __ F1 F2 F3 F4 F5 | F6 F7I F8 F9 F10 F11

2 1901 1 2 -
17 1912 4 4 2 --
18 1912 2 3 1 -
19 1912 1 I- I- -
20 1912 1 1 4 1 -
37 1913 1 -
38 1913 1 4 11 20 26 40 33 27 13 4 2 1
59 1915 6 14 17 13 16 11 7 2 -
81 1916 8 11 8 9 8 1 -
103 1918 0 -
104. 1917 0 -
105 1918 1 2 -
106 1918 2 -
115 1917 4 5 4 5 8 9 1 -
116 1917 1 -
117 1918 1 -
213 1924 3 6 11 15 9 4 -
225 1924 3 9 11 10 4 4 -
236 1924 4 5 0 -
306 1928 0- -
538 1933 0- -
539 1933 7 5 2 - I
540 1933 2 1 0 I-
541 1933 2 1 2 -
581 1935 2 0 -
582 1935 2 3 3 1 -
802 1939 0 -
803 1939 0 -
804 1939 1 2 0 -
805 1939 1 1 -
806 1939 5 11 4 -
888 1940 2 0 -
889 1940 3 2 1 -
B-9 1942 3 2 -
W230 1945 0 -
W236 1945 1 -- -
W256 1945 1 -
W260 1945 2 -
W269 1945 2 -
1 I I





TABLE 6.-NUMBERS AND CAUSES OF LOSES OR REASONS FOR DISPOSAL OF PROGENY OF 39 FOUNDATION COWS FROM THE
STATION DAIRY HERD OVER A 47-YEAR PERIOD.
SI i I Time
Founda- Total I Low I Left No Disease ] I Total I Total I Family
tion Female Died I Produc- I Non- Female or I Sold Leaving I in Herd 1950 Remained
Cow Progeny | tion breeder Progeny Accident I I Herd I 1950 Herd in Herd
Percent (years)
2 3 0 0 0 3 0 0 3 0 19
17 10 2 0 1 1 1 5 10 0 13
18 6 2 0 3 0 1 0 6 0 -- 21
19 1 0 0 0 1 0 0 1 0 9
20 7 2 1 1 3 0 0 7 0 17
37 1 0 0 0 1 0 0 1 0 7
38 181 33 18 25 6 53 2 137 44 31.65 37*
59 86 17 9 14 3 18 6 67 19 13.66 35*
81 45 12 8 8 1 10 4 43 2 1.44 34*
103 0 0 0 0 0 0 0 0 0 3
104 0 0 0 0 0 0 0 0 0 7
105 3 0 0 0 3 0 0 3 0 6
106 2 0 0 0 2 0 0 2 0 5
115 36 9 5 7 2 11 2 36 0 26
116 1 1 0 0 0 0 1 0 7
117 1 0 0 0 0 1 0 1 0 -- 3
213 48 12 14 5 1 3 3 38 10 7.20 26*
225 41 6 1 3 1 11 0 22 19 13.66 26*
236 9 3 2 2 1 1 0 9 0 19
306 0 0 0 0 0 0 0 0 0 1
538 0 0 0 0 0 0 0 0 -- 7
539 14 5 1 2 0 4 0 12 2 1.44 17*
540 3 0 2 0 1 0 0 3 0 13
541 5 1 0 0 0 0 0 1 4 2.88 17*
581 2 1 0 0 0 1 0 2 0 -- 6
582 9 1 0 1 0 4 0 6 3 2.16 15*
802 0 0 0 0 0 0 0 0 0 1
803 0 0 0 0 0 0 0 0 0 5
804 3 1 1 0 0 1 0 3 0 5
805 2 0 0 0 0 0 0 0 2 1.44 11*
806 20 1 0 0 0 1 0 2 18 12.95 11*
888 2 1 0 0 1 0 0 2 0 7
889 6 0 2 0 0 1 0 3 3 2.16 10*
B-9 5 1 0 0 0 1 0 2 4 2.88 8*
W230 0 0 0 0 0 0 0 0 1 0.72 5*
W236 1 0 0 0 0 0 0 0 2 1.44 5*
W256 1 0 0 0 0 0 0 0 2 1.44 5*
W260 2 1 0 0 0 0 0 1 2 1.44 5*
W269 2 1 0 0 0 0 0 1 2 1.44 5*
Families represented by living animals in 1950.







18 Florida Agricultural Experiment Stations

clusion. Of 10 foundation cows, one may expect about half to
remain or to have descendants living in the herd at the end
of a decade.
Female descendants by generations and the causes of losses
of the progeny of 39 foundation cows are shown in Tables 5
and 6.
Of 33 foundation cows, 18 were represented into the second
decade, seven into the third decade, and three into the fourth
decade. Eleven families were still represented in 1950. Six
new families had been in the herd less than 10 years.
USEFUL LIFE OF DAIRY COWS
The average useful age of dairy cows is considerably lower
than that of bulls because of early culling for low production,
udder troubles and breeding irregularities. Various investiga-
tors have found that the average productive life span of dairy
cows is between 3.5 and 6.0 years. The average reproductive
life span is shorter than the period of productive usefulness
because production usually continues after the final calving. The
average cow in commercial dairy herds bears from three to
five calves. Generally, cows in larger herds have a shorter period
of usefulness than those in smaller herds. Home-raised replace-
ments generally have a longer useful life than purchased re-
placements.
RECORDS OF INDIVIDUAL COWS
As discussed previously, records of production, reproduc-
tion and transmitting ability are essential in dairy herd opera-
tions. Milk and butterfat production may be obtained under
supervision of Herd Improvement Registry, Dairy Herd Improve-
ment Associations, or privately, depending upon the owner's
preference. Five examples from the Station herd will illustrate
the relation of age, breeding efficiency and calving interval in
herd management with individual cows.
Cow No. 114F
Services per | Age at [ I I
Conception I Calving Calf* [ Milk I Test L Fat In Milk
Iyr.mo.day pounds) percent Ipounds days
1 2-8-18 M 289-F 5,828 5.80 338 363
1 4-0-15 F 387-F 5,228 5.36 280 280
1 5-0-5 F 461-F 4,335 5.41 234 238
1 6-0-19 F 558-F 9,353 5.58 522 323
4 7-2-15 M 675-F 5,506 5.30 293 267
3 8-3-12 M 815-F 287 (Mastitis) 16
S___________________30,537
Male or female and tatto number.









Building A Dairy Herd 19

Cow No. 928 UF
Services per Age at I I
Conception Calving I Calf* Milk Test I Fat I In Milk
) yr.mo.4ay Ipounds percent pounds I days
1 2-6-8 F 70-F 4,209 4.45 187 347
1 3-7-0 F 114-F 6,070 5.85 355 405
1 4-9-2 F 184-F 9,866 4.56 451 358
1 1 5-9-19 F 249-F 7,604 5.14 1 391 320
1 6-9-18 M 333-F 8,926 4.53 404 342
7 8-4-14 F 440-F 9,335 4.38 409 346
1 9-4-27 M 526-F 9,005 4.46 402 393
4 10-7-23 M 656-F 9,155 4.30 393 319
1 11-7-2 M 767-F 7,077 4.54 321 357

71,247 _
Male or female and tatto number.
Cow No. 949 UF
Services per Age at I I
Conception Calving I Calf* I Milk I Test I Fat I In Milk
I yr.mo.day I pounds percent pounds | days
1 2-11-25 F 99-F 5,835 5.48 320 386
1 4-1-11 M 155-F 4,224 5.33 226 282
1 4-11-28 F 234-F 6,098 5.95 363 330
1 1 5-11-22 F 299-F 5,037 6.18 311 322
1 7-0-18 F 373-F 7,901 5.05 399 307
1 8-0-29 M 453-F 8,858 5.26 466 345
1 9-1-2 F 548-F 5,627 5.36 302 364
9 Fetus 646-F; slaughtered
_________43,581 |__
Male or female and tatto number.
Cow No. 34-F
Services per Age at | I
Conception Calving I Calf* Milk I Test Fat I In Milk
I yr.mo.day I Ipounds percent I pounds I days
1 2-9-28 M 175-F 9,110 4.93 450 421
1 4-1-16 M 269-F 7,934 5.21 414 316
2 5-4-2 F 358-F 10,787 4.66 503 309
1 6-4-28 M 433-F 10,442 4.39 458 375
2 7-6-28 F 538-F (died after calving)

S______38,273 _
Male or female and tatto number.
Cow No. 283-F
Services per Age at I
Conception Calving Calf* Milk Test Fat I In Milk
I yr.mo.day II pounds I percent pounds I days
1 2-3-29 M 452-F 7,729 4.99 386 365
3 3-6-12 F 567-F 9,619 4.63 446 381
3 4-8-8 M 689-F 11,023 5.03 555 323
2 5-8-25 I M 817-F ] Lactation current
5 7-past I pregnant
I 28,371 _
"* Male or female and tatto number.








20 Florida Agricultural Experiment Stations

The production of a cow usually increases with age, although
instances are not infrequent in which the first lactation is the
best. For example, the first and fourth lactations of cow No.
114-F exceeded her other lactations. (See page 18.)
In general, cow No. 114-F had a high breeding efficiency, con-
ceiving at the first service in four instances, except that the first
breeding was somewhat delayed for a Jersey.
Only one calving interval exceeded 14 months, so she was
considered to be a regular breeder with a high conception rate.
The daughters have had desirable production and reproduction
records. The third was slaughtered because of failure to con-
ceive.
Cow No. 928 UF, except in two instances, had good breeding
efficiency usually dropping a calf each 12 to 15 months. She
was a persistent milker of the type many dairymen call a "four-
gallon" Jersey. One daughter died for an unknown reason at
one month of age. Four daughters were producing cows, mostly
of medium ability. Cow No. 114-F, previously mentioned, was
one of these.
Cow No. 949 UF was past two years old at first breeding.
She had an outstanding breeding history in rate of conception
and frequency of reproduction until more than nine years old.
Four of her five daughters were satisfactory producers. The
fifth was started off poorly; her outcome is still questionable.
When slaughtered at the age of 10 years, 1 month and 10 days,
she was carrying a 1.0 gram fetus.
Cow No. 34-F is an example of higher production, year after
year, with a longer calving interval and reasonable breeding
efficiency. On the whole, intervals between calving were longer,
but she was a persistent, steady milker.
Cow No. 283-F was a heavy, persistent milker. Yet somewhat
low breeding efficiency lengthened the interval between calvings
and reduced efficiency in daily milk production over the life
period.

I Age at I Time from 2 No. of I
Cow I First Years Old to Lacta- Total JAv. Daily
No. I Calving Last Dry Date tions Milk Milk Yield
Syr.mo.days days Ipounds pounds
928 UF 2-6-8 2,596 9 71,247 1 27.4
949 UF 2-11-25 3,589 7 43,581 1 12.4
34-F 2-9-28 1,985 4 38,273 19.3
114-F 2-8-18 2,738 5 30,537 11.2
283-F 2-3-29 1,308 3 28,371 21.7







Building A Dairy Herd 21

Records serve several purposes in building a dairy herd. For
a summary of the records of the five cows used see preceding
page.
Attention should be called to the accomplishments of cow
No. 928 UF. Although she had no outstanding record in any
one year, good breeding efficiency and regular reproduction per-
mitted her to make an average milk yield of 27.4 pounds daily
during her productive lifetime. Cow 34-F gave higher individual
lactation records. Yet in her lifetime milk production averaged
19.3 pounds daily.
BROOD COW FAMILIES
Hereditary genes that contribute to milk production are num-
erous. In cows, 30 pairs of chromosomes are recognized in cell
nuclei. The genes, or hereditary units, that contribute to herit-
able characteristics are located on these chromosomes in com-
plex relationships.
Many genes control peak milk production, persistency of lacta-
tion, and butterfat. These characters are inherited indepen-
dently. The unknown numbers of genes and complex relation-
ship now make it impossible to segregate and recognize their
individual influences. Their gross effect is seen mainly in the
analysis of milk and butterfat yields, which are also modified
by feeding and management.
To illustrate the principles of herd building based on cow
families, several such families have been selected.










.." "* r" .

h .,, . ** s '.,s




Fig. 4.-Une of the daughters of Sophie 19th's Victor 81st, closely related
also in female line to cow 375 UF.







22 Florida Agricultural Experiment Stations

Four of the cows in the Station herd lived beyond the usual
life span and dropped three or more daughters. For this reason
these four cows were chosen in order to analyze their ability
to transmit production. All of their daughters were by the
same sire and thus are paternal half-sisters.
Cow 375 UF was a good producer. She completed six lacta-
tions, dropping four female and three male calves before her
usefulness was terminated by an accident. Two of the bull
calves went into commercial herds where their progeny were
regarded sufficiently well that both bulls were used later in
other herds. Actual production of 375 UF and her daughters
follows:


Cow I Lactations I Average Yearly Records
__ __Milk I Test Butterfat
I pounds percent pounds
375 UF 6 8,187 5.57 456
Daughters
507 UF 6 8,411 5.12 431
614 UF 3 5,489 4.74 | 260
677 UF 4 8,210 4.93 405
841 UF 6 6,725 4.89 329

Cow No. 375 UF may have been better hereditarily than the
bull with which she was mated. Two daughters equaled her
in milk production, while two others were lower. A close rela-
tive, showing characteristics of this family, can be seen in Fig-
ure 4.
Another cow with several daughters was No. 370 UF. She
dropped three female and five male calves. None of her bull
calves were sold for breeding, since she was not considered of
sufficient ability. The records of cow and daughters follow:


Cow I Lactations I Average Yearly Records
__I Milk [ Test Butterfat
pounds percent pounds
370 UF 8 6,448 5.12 330
Daughters
484 UF 5 8,306 4.42 367
570 UF 3 7,779 5.66 440
896 UF 1* 4,409 4.65 205

Mastitis during first lactation.

Though the same sire is concerned as with No. 375 UF's
daughters, it would appear either that the bull exceeded 370 UF








Building A Dairy Herd 23

in transmitting ability or that 370 UF transmitted capacity for
higher production than she herself attained.
Cow No. 401 UF dropped five male and four female calves.
She qualified for the Register of Merit in the first lactation.
One bull calf went into a registered Jersey herd where his
daughters were regarded as above average. One of them was
a state leader for the breed. One heifer failed to conceive. Life-
time production of 401 UF and her three daughters follows:

Cow I Lactations Average Yearly Records
SMilk I Test Butterfat
I pounds I percent pounds
401 UF i 9 5,805 5.24 304
Daughters 1
537 UF 4 7,100 5.30 376
637 UF 3 6,487 4.92 319
933 UF 3 7,805 5.20 406


It appears probable that 401 UF transmitted few factors for
low production, and that for this reason the sire with which
she was mated had more chance to bring improvement to all
of these daughters.
A fourth cow with several daughters was 431 UF. She was
a low producer, by a sire discarded for transmitting low pro-
duction to seven out of eight of his daughters. However, 431 UF
was retained in the breeding investigation during her natural
lifetime. Six of her daughters were full sisters; another died
in calfhood. One daughter had mastitis early in the first lacta-
tion.

Cow Lactations I Average Yearly Records
___I Milk I Test Butterfat
Pounds percent pounds
431 UF 7 3,806 5.04 192
Daughters
482 UF 6 4,911 5.17 254
564 UF 4 6,184 4.92 304
612 UF 2 4,300 5.63 242
670 UF 1* 1,512 4.37 66
720 UF 1 3,667 5.67 208
792 UF 2 3,994 5.71 228

Mastitis early in first lactation.

Cow No. 431 UF tended to hold down production of her
daughters, even though five with normal lactations were con-
sistently better producers at corresponding ages than their dams.








24 Florida Agricultural Experiment Stations

No. 431 UF produced 1,591 pounds of milk and 104 pounds of
butterfat in her first lactation.
These four cows and their daughters have been used as
examples to show the influence of brood cows in building dairy
herds. Animals descended from 431 UF were culled in later
years for low production, so as not to perpetuate a low-producing
family.
BROOD COWS THROUGH GENERATIONS
The divergent contributions of two brood cows will be il-
lustrated by two examples from the Station herd. Cows 213 UF
and 225 UF entered the Station herd in 1924. From informa-
tion then available, these two cows appeared about equally de-
sirable for foundation purposes. They and their progeny were
contemporaneous, and were mated with Jersey bulls in the herd
during the next five or six generations. Cow 213 UF was the
ancestor of 20 female descendants in six generations that pro-
duced an average of 5,667 pounds of milk in 49 lactations, as
computed to a uniform 305-day mature equivalent basis. Dur-
ing the same period 24 descendants of 225 UF in five genera-
tions averaged 7,779 pounds of milk in 70 lactations. Average
milk production of the respective descendants is summarized in
Table 7.

TABLE 7.-AVERAGE MILK PRODUCTION OF DESCENDANTS IN FIVE GENERA-
TIONS FROM TWO FOUNDATION COMES
I I Average Milk
Generations I Number of Cows I Lactations I Production
I I pounds
Foundation Cow No. 213 UF

First 2 7 6,118
Second 2 8 3,580
Third 5 12 5,720
Fourth 6 15 5,908
Fifth 4 6 6,825
Total ............. 19 48 --
Average per lactation ..................................... 5,618
Foundation Cow No. 225 UF

First 3 14 6,408
Second 5 21 7,125
Third 5 19 8,824
Fourth 7 12 8,498
Fifth 4 4 8,924
Total .............. 24 70__--
Average per lactation ............-...........-- .........--- 7,799







Building A Dairy Herd 25

There was a striking difference in milk production between
these two cow families in each of the five generations, 225 UF
being the higher yielder.
Constant vigilance is required to eliminate low-producing in-
dividuals in all families, especially from low-producing dams.
Dairy cattle are recognized as being so mixed in hereditary make-
up that few animals have been known that transmitted desirable
qualities to all of their progeny. Constructive breeding requires
as much attention to cow families as to sampling and proving
herd sires.

ACCOMPLISHMENT FROM SELECTIVE BREEDING
A broader example of breed improvement comes from the
province of Friesland in the Netherlands. Over a half-century,
through selective registration and use of bulls out of high-testing
cow families, substantial changes have taken place in average
milk yields and percentage of butterfat in milk of the herdbook
cows in this province. Average production records of the herd-
book cows were as follows:

I I
Year I Number of Cows _Average Production
____I Milk Test I Butterfat
pounds percent pounds
I
1895-1897 162 9,319 3.11 289.6
1910 8,524 9,594 3.18 305.1
1921 14,837 9,541 3.40 324.4
1930 15,574 10,562 3.64 384.5
1952 37,892 10,692 3.99 428.8

These changes have come about perhaps partly by better feed-
ing and management, but largely by selecting herd sires from
higher testing cow families. Small government subsidies for
bulls are received only for those that meet certain production
standards in their pedigrees. Brood cows with low butterfat
tests have been discriminated against when selecting young bulls
for breeding purposes.

BREEDING EFFICIENCY AND REPRODUCTION IN
HERD BUILDING
BREEDING EFFICIENCY
Regular reproduction, preferably at yearly intervals, is im-
portant in economical milk production. Many factors affect re-
production with both male and female. The female reproduc-







26 Florida Agricultural Experiment Stations

tive tract is somewhat more vulnerable than the male to inter-
ference with normal reproduction. Malfunctions generally are
more prevalent in the female than the male. These may include
cystic ovaries, retained yellow bodies corporaa lutea) and lack
of implantation of the fetal membranes of a fertilized ovum, or
poorly implanted membranes (early abortion) which may go un-
noticed in the early stages or before cotyledonous attachment.
Infections and infectious diseases may be present in either sex
and adversely affect normal reproduction. Brucellosis (Bang's
disease) has been the greatest cause of low breeding efficiency
through abortion and damage to the cotyledons and lining (en-
dometrium) of the uterus. Control measures are reducing this
disease. Trichomoniasis and vibriosis are other diseases which
interfere with normal reproductive functions, while leptospirosis
is known to cause abortion. Many different organisms may in-
fect the linings of the vagina, cervix, uterus and even Fallopian
tubes. Such inflammatory conditions are named for the area
involved, as vaginitis, crevicitis, endometritis and salpingitis.
Although bulls sometimes contract brucellosis, it seldom is trans-
mitted by the bull at the time of service. Most of the other
above-mentioned infections may be acquired and spread by the
male in natural breeding. Use of treated semen in artificial
breeding is a helpful means of preventing spread of venereal in-
fections.
AGE AFFECTS BREEDING EFFICIENCY
Many cows leave the dairy herds for various reasons before
senility reduces their capacity to bear calves. Most bulls, al-
lowed to live their useful life span, go out of service as "non-
breeders". However, many of these nonbreeders have live motile
spermatozoa but for other reasons may not be able to bring about
pregnancy. Others may be active but produce spermatozoa
poorly formed or low in motility. While individuals vary widely,
most normal dairy animals are capable of satisfactory repro-
duction up to 10 or more years of age, providing they are in
healthy herds and have capable veterinary attention concerning
reproductive malfunctions. A few dairy cows have borne calves
when 24 years old and some dairy bulls have been in satisfactory
service even beyond 19 years of age.
Table 8 presents data of 1,019 calvings from 1,652 natural
services by bulls from one to 12 years of age, and out of cows
bearing one to 10 or more calves. This is an average conception
rate of 61.7 percent, or one calf for each 1.62 services over a
20-year period in the Station herd. Bulls between the ages of








Building A Dairy Herd 27

one and two years produced the highest conception of any age
group. However, the 12-year-old bulls sired three calves from
three services-too few cases to regard as truly representative.
Bulls between two and 12 years ranged from 52.6 to 69.7 per-
cent in breeding efficiency, tending to decrease in fertility with
advancing age. The first three calvings from cows required
fewer services than subsequent calves, as may be seen in the
last column of Table 8. Thereafter, average breeding efficiency
decreased with increasing age, except in the last group of cows
that had borne 10 or more calves. The numbers of these aged
cows are too few to be considered a reliable trend.

SELECTION OF CALVES TO BE RAISED
If a dairy herd is to be maintained wholly from homegrown
replacements, what proportion of heifer calves should be selected
to be raised?
Various estimates have placed this figure between 50 and 75
percent of the heifer calves dropped-or around 19 to 28 heifer
calves annually per 100 milking cows. Daughter-dam compari-
sons were made of a complete population of animals raised in
the Station herd during the period when the policy was to keep
all heifers and to measure their production. Milk and butterfat
yields of 200 daughters were compared with those of their dams,
using actual records at corresponding ages, insofar as possible.
These production records were up to 365 days in length, with
cows milked twice daily. The comparisons are shown in Table 9.
From records in Table 9, the tendency is seen for daughters
from low-producing dams to increase somewhat in producing
ability. The tendency was for daughters of higher producing
cows to exceed the average of the herd, but not quite equal the
production of their dams generally. With Jerseys under these
conditions, the daughters equaled the dams at about a produc-
tion level of 6,250 pounds of milk and 310 pounds of butterfat
in 365 days. It would appear, therefore, that heifer calves should
be retained in most instances from cows nearly equal to, or
above, the average production of the herd. Heifers from a family
known to be good would be preferred to those from a good in-
dividual cow from a generally poor family.

HEIFERS THAT SURVIVE
Since maintenance of a dairy herd often depends upon home-
grown replacements, it is important to know the survival of





TABLE 8.-RELATION OF ORDER OF CALVING AND AGE OF BULL TO CONCEPTION RATE, BASED ON 1,019 CONCEPTIONS
FROM 1,652 SERVICES
]I I Services
Order of I Age of Bull, Years \ Rate of Number of I per
Calving 1 2 3 4 I 5 6 7 8 9 10 11 12 Concep- Serv- Concep-1 Concep-
per Cow Percentage of Conceptions I tion ices tions I tion
I | | | | percent
First ............ 76.3 67.6 57.6 68.6 I 75.0 i 61.9 83.3 61.1 83.3 50.0 66.6 1100.0 67.5 400 270 1.48
Second .......... 69.2 73.7 56.6 61.8 82.8 I 53.8 80.0 70.6 45.9 77.8 50.0 |-- 65.3 340 222 1.53
Third ............ 66.6 56.4 68.6 66.6 89.5 1 82.4 81.8 50.0 65.0 76.9 66.6 -- 67.4 267 180 1.48
Fourth ..-..... 100.0 61.5 41.9 55.2 57.9 1 71.4 88.9 72.7 35.2 63.6 50.0 1100.0 55.9 229 128 1.79
Fifth .......... 50.0 37.5 44.1 54.5 56.0 66.7 71.4 62.5 83.3 50.0 44.4 53.4 161 86 1.87
Sixth ......... 100.0 33.3 57.1 43.5 75.0 50.0 36.4 85.7 36.4 50.0 100.0 I-- 52.5 118 62 1.90
Seventh ...... -- 100.0 50.0 26.7 58.3 66.7 100.0 62.5 62.5 100.0 -- 55.4 56 31 1.81
Eighth .......... 25.0 40.0 100.0 66.7 1100.0 60.0 33.3 60.0 33.3 -- -- 51.4 37 19 1.95
Ninth ...........--- 100.0 -- 40.0 100.0 40.0 50.0 27.3 -- I 42.3 26 11 2.36
Tenth and I I i
over ............ -- 33.3 50.0 I-- 50.0 75.0 50.0 .0 1.0 I-- -- 55.6 18 10 1.80

Average ...... 73.5 64.4 54.8 1 59.0 69.7 64.2 67.1 61.5 52.6 56.5 | 59.3 1100.0 61.7 _

Services ........ 117 267 290 305I 175 95 79 109 116 69 27 3 1,652
Conceptions 86 172 159 180 122 61 53 67 61 39 16 3 -- 1,019
Services per j I I I i
conception 1.36 1.55 1.821 1.69 1.431 1.56 1.49 1.63 1.90 1.77 1.691 1.001 -- 1.62


TABLE 9.-RELATION OF DAUGHTERS' PRODUCTION TO THAT OF THEIR DAMS' UNDER SIMILAR CONDITIONS. *

Dams' I Lactations I Daughters I Dams I Percentage of Daughters
Butterfat I ___Excelling Dams in
Range Pairs Daughters | Dams Milk Test Fat I Milk | Test I Fat I Milk Test [ Fat
Ibs. I lbs. % lbs. I lbs. % lbs. I % % %
100-149 12 23 23 4,861 5.08 247 2,683 5.00 134 92 42 92
150-199 14 40 40 5,320 5.33 284 3,983 4.65 185 71 79 86
200-249 35 78 79 5,809 5.07 295 4,598 4.96 228 80 49 86
250-299 49 128 116 6,140 5.03 309 5,424 5.04 274 67 49 69
300-349 50 126 117 5,970 5.18 309 6,301 5.15 325 38 52 38
350-399 23 58 52 6,623 5.12 339 7,223 5.19 375 25 39 30
400-449 11 24 23 6,305 5.14 324 7,763 5.33 413 18 27 9
450-499 6 29 29 7,085 4.91 348 8,842 5.29 468 25 13 0

All records are from Jersey cows milked twice daily in the Florida Agricultural Experiment Station dairy herd, on a 365-day basis at com-
parable ages.







Building A Dairy Herd 29

heifer calves and the causes of losses. As reported previously,3
65.2 percent of Jersey heifer calves born over a 20-year period
survived and entered the milking herd. Scours and coccidiosis
caused death of 17 animals, mostly at less than six months of
age. Various diseases or disease-suspects removed 31 heifers.
Accidents accounted for six; bloat, poison and deformity each
eliminated one animal. Six were weak at birth and died within
10 days. Fifteen animals died of unrecorded causes. Thirty-
nine animals either failed to conceive or were assigned to experi-
mental work because of unsatisfactory breeding histories. This
left 266 heifers that conceived and entered the milking herd,
from 408 born during this period. A summary of these heifers
is shown in Table 10.

TABLE 10.-HEIFER CALVES DROPPED OVER A 20-YEAR PERIOD, THEIR LOSSES
AND SURVIVALS.

I Number I Percentage

Female calves born ...---.....--................--- 408 -
Causes of losses:
Stillborn or died at birth ........-----...... 20 4.9
Freemartins ....................................... ----5 1.2
Scours and coccidiosis ............................. 17
Diseases and disease suspects ........---...... 31
Weak at birth (died within 10 days) ... 6 19.1
Accidents .................... --....... --........... -- 6
Poison, bloat, deformed ............----......... 3
Unknown ................----.......... ..........---. 15
Failure to conceive .................-- .............. 39* 9.6
142
Entered milking herd .............-- --.......-..--.. 266 65.2

These 39 heifers include 19 with unsatisfactory breeding histories that were consigned
to experimental work, but not necessarily sterile or barren.

An analysis of complete reproductive histories from 275 Jersey
cows in the Station herd showed an average of 1.8 female progeny
per cow, including freemartins, in the average reproductive life-
time. Deducting losses, there was an average of 1.2 females
per dam that became replacements in the herd. Age at 'first
calving and length of intervals between calvings in any herd may
influence the numbers of heifer calves per dam.

P. T. Dix Arnold and R. B. Becker. Dairy Calves, Their Development
and Survival. Fla. Agr. Exp. Sta. Bull. 529: 4-23. 1953







30 Florida Agricultural Experiment Stations

AGE AT FIRST CALVING AND LIVING CALVES DROPPED
Many workers have indicated the desirability of developing
heifers to good size so that they are ready to enter the milking
herd at an early age. Eckles4 found that light feeding retarded
growth and sexual maturity, as compared with heifers well
fed. The higher production records were by animals of good
size when coming into milk, though little effect was noted on
actual breeding efficiency. Calving at an extremely early age
was detrimental to milk production, while nothing was gained
by too long a delay in time of first calving.
McDowell5 and Gowan6 have found that within the dairy breeds
the larger cows on the average are the heavier producers.
The Jerseys, in the study of age at first calving, dropped their
first calves from 17 to 57 months of age. Only 16 animals calved
under two years old; 162 when 24 to 30 months (730 912 days) ;
73 at 31 to 36 months (912 1095 days); and 24 when older.
Of this total number of heifers one-third would be considered
as problem breeders, having calved after 31 months of age. The
average for the Station Jersey herd was at 30 months of age.
The largest group of heifers, 48 in all, dropped their first
calves at 850 to 899 days of age. At the second calving they
dropped 42 calves; at the third calving 35, and so on, producing
a total of 186 living calves. These 186 calves were 16.7 percent
of the total number produced. An analysis of these records and
subsequent calvings is given in Table 11. There was a marked
tendency for late-calving females to drop fewer calves per cow.
CALVING INTERVALS
The amount of milk and butterfat that a cow yields during
her lifetime is limited by several factors: age at first calving,
level and persistency of milk production, and the intervals be-
tween calvings. Intentional management and breeding efficiency
affect the calving intervals. The useful life span of dairy cows,
breeding efficiency, rate of replacement (sex ratio, livability,
age at first freshening, reproduction by heifers) and calving
interval combine in maintaining a dairy population. A breeding
efficiency of one calf per 365 days is considered ideal, but is a
difficult goal to attain.
C H. Eckles. The ration and age of calving as factors influencing the
growth and dairy qualities of cows. Mo. Agr. Exp. Sta. Bull. 135: 3-91.
1915.
J. C. McDowell. Within the breed the large cows pay. U. S. Dept. Agr.
Circ. 114: 1-4. 1930.
J. W. Gowan. Fifty-Seventh Annual Meeting A. J. C. C. Jersey Bul-
letin and Dairy World 44(23): 1001, 1014. June 10, 1925.









TABLE 11.-AGE AT FIRST CALVING WITH RELATION TO LIVING CALVES DROPPED IN SUCCESSIVE ORDERS OF CALVING.

Age at Number of Living Calves Dropped P percent
First Calf CalvingI of Total
I 1st 2nd I 3rd 4th 5th 6th I 7th 8th | 9th I 10th l11th 12th 13th I Total I_
days |
500- 549 ................. ... 3 3 3 3 -- 12 1.1
550- 599 ..................... - -
600- 649 ..................... 3 3 3 1 1 1 1 1 1 15 1.3
650- 699 ........................ 6 5 4 3 21 2 2 1 1 1 27 2.4
700- 749 ................. 16 16 15 12 10 4 2 75 6.7
750- 799 ....................... 38 36 31 25 191 13 7 6 4 2 1 182 16.3
800- 849 ...................... 40 30 24 20 161 13 7 4 2 1 1 1 159 14.2
850- 899 ................... 48 42 35 23 141 11 7 4 2 186 16.7
900- 949 ...................... 30 27 21 17 11 7 4 2 1 120 10.8
950- 999 .................. 23 20 12 11 91 5 1 1 82 7.4
1,000-1,049 ...................... 21 18 17 12 61 3 2 2 82 7.4
1,050-1,099 ............-- 17 12 8 8 81 5 4 3 1 1 1 1 1 70 6.3
1,100-1,149 ......................3 11 9 7 5 31 2 -. 37 3.3
1,150-1,199 ...................... 5 4 3 2 1 1 1 1 1 19 1.7
1,200-1,249 ................... 4 2 1 7 .6
1,250-1,299 ...................... - - -
1,300-1,349 ................. 6 5 4 4 3 3 2 27 2.4
1,350-1,399 ................- - -. -. - -
1,400-1,449 ............... 1 1 1 1 -- 5 .4
1,650-1,699 .............. 1 1 1 1 1 1 1 -- 7 .6
1,700-1,749 .................. 2 2 1 -- 5 .4


Total ................................ 275 236 191 149 1051 71 41 25 13 5 3 2 1 1,117
Percentage ...................... 24.6 21.1 17.0 13.4 9.4 6.4 3.7 2.2 1.2 .4 .3 .2 .1 100.0

34
i-






32 Florida Agricultural Experiment Stations

A brucellosis-free herd at the University of Illionis had a
424-day calving interval. To maintain a herd with home-raised
replacements at this reproductive rate would involve the in-
tended saving of heifer calves from about 80 percent of the
cows, varying with degree of success in saving and raising heifers
and in conception at desirable ages.
All Jersey cows in the Station dairy herd were placed on
Register of Merit test for 365 days in the first lactation. In
order that advancing gestation not restrict the production record
unduly, milking heifers were not re-bred before four to five
months in lactation. This entailed some delay, or extension
of the first calving interval. A gradual change to a 305-day
test period was made during 1949-1950, with an intended cor-
respondingly earlier subsequent calving. Needs for cows in
proper stage of lactation for winter feeding trials, or for sum-
mer grazing trials, modified the subsequent breeding schedules,
but mainly the intent was toward a 365-day calving interval-
a goal seldom attained except by cows with high breeding
efficiency.
Since all cows were on Register of Merit test in the first lacta-
tion, with intentionally delayed breeding, the first calving interval
was tabulated separately. The average length of consecutive
calving intervals is shown in Table 12.

TABLE 12.-CALVING INTERVALS IN THE FLORIDA AGRICULTURAL
EXPERIMENT STATION DAIRY HERD (1929 1950).
Calf I Number of Calvings | Interval to Next Calving
days
1st ................................ 235 468.3
2nd .............................. -191 423.3
3rd ...-...................---- --- 147 430.7
4th ..............................-. 102 422.6
5th ......---....................... 70 416.4
6th ................................ 42 416.8
7th ........ ------.. ............ 26 441.8
8th -----.---------............ 14 456.6
9th .............................. 7 440.7
10th ................................ 3 460.7
11th ................................ 2 381.5
12th ..--- --..................-... 1 374.0
840
Average of all intervals .... 437.4
Average (2nd to 12th) .--. 605 425.5

The effect of delayed breeding during the first lactation is
shown by an average interval of 468 days before those animals
dropped their second calves. This was 43 days longer than the








Building A Dairy Herd 33

average of subsequent calving intervals. Intervals were com-
puted only to the next "normal" calvings. Importance of a calv-
ing interval approaching 365 days is based on the larger propor-
tion of days during the lactation when the cow is in maximum
daily production.

CALVING INTERVALS AFFECT AVERAGE DAILY MILK YIELDS
Is the cow with the large 305-day record always the heavy
producer during her working lifetime?
A study of average daily production of Jersey cows in the
Station herd was made, based on the total interval between suc-
cessive calvings. This included both the days in milk and the
dry period up to the next calving time. Cows with delayed
breeding and those that failed to conceive promptly had longer
calving intervals and frequently dry periods longer than desired.
Feeding, care and overhead expenses continue with cows whether
milking or dry. Previous work with this herd showed that
optimum production was obtained following a six to eight week
dry period7.

TABLE 13.-ANALYSIS OF TOTAL AND AVERAGE DAILY MILK PRODUCTION
DURING CALVING INTERVALS OF DIFFERENT LENGTHS.

Intervals Number I Milk Production*
Between I of I Av. per Average per Day Throughout
Calvings I Records I Lactation Entire Calving Interval
days I pounds Ipounds
365 and less** .----....... 93 7,142.8 20.73
366 to 385 .....-......... ------ 55 8,535.9 22.76
386 to 405 ...................-... 46 7,809.7 19.77
406 to 425 .--. -.....- ....--... 54 8,253.8 19.89
426 to 445 ...--....---............ 36 8,971.3 20.62
446 to 465 ...-...-------- . 29 8,706.0 19.13
466 to 485 .............-- 20 8,817.2 18.56
486 to 505 ....---................. 14 9,121.9 18.43
506 to 525 ..--------------- 18 9,240.2 17.94
526 to 545 ........- -----... 6 11,156.0 20.85
546 to 565 -................ ...... 11 9,288.6 16.74
Over 566** .........-- 34 9,846.6 14.96
Total ............................. 416 8,385.6 18.03
Computed to a uniform mature equivalent basis of 4% fat corrected milk.
** The actual days between calving in the group of 365 days or less was 344.6 days, and
for the group over 566 days was 658 days.

The milk production during 416 working intervals (between
calvings) was computed for calving intervals of less than 365

SP. T. Dix Arnold and R. B. Becker. Influence of preceding dry period
and of mineral supplement on lactation. Jour. Dairy Sci. 19:257-266. 1936.







34 Florida Agricultural Experiment Stations

days up to those over 566 days in length. These records were
grouped by 20-day intervals for convenience. The analysis of
these 416 records is presented in Table 13.
The 93 calving intervals of 365 days and less actually averaged
344.6 days, while the 34 records over 566 days averaged 658 days.
When the average gross milk production was computed on the
daily basis per calving interval, it was found that there was a
desirable correlation between high breeding efficiency (calving
at intervals of 385 days or less) and high average daily milk
production. As calving intervals lengthened, average daily milk
production tended to decrease at a fairly uniform rate. There
were two exceptions. The group of 36 records at the 426-445 day
intervals included 11 of the better cows in the herd, tending to
draw the average daily milk production upward. The six records
with 526-545 day calving intervals also included four of the better
cows and are too few to be considered reliable. The average


25



20



o15



10



5



CALVING INTERVAL, DAYS
t KiAt 0It to W)6

Fig. 5.-The computed average milk production per day tended to be
higher -with the shorter calving intervals, irrespective of total yields dur-
ing the lactation.







Building A Dairy Herd 35

daily milk production for the groups with different calving in-
tervals is shown in Figure 5.
The importance of calving intervals with relation to total pro-
duction may be illustrated from the records of two closely re-
lated cows. These cows were sired by the same bull and their
dams were related. They were born 60 days apart, were to-
gether in the herd their entire lives, and left the herd 71 days
apart.
The first of these two cows yielded 7,795 pounds of milk in
her first lactation and was considered a desirable animal. She
dropped four calves at 2 years 10 months; 4 years 9 months;
6 years; and 7 years 6 months of age. During her lifetime she
produced 35,142 pounds of milk.
The second cow produced 6,492 pounds of milk in her first
lactation. She dropped six calves at 2 years 4 months; 3 years
5 months; 4 years 4 months; 5 years 5 months; 6 years 5 months;
and 7 years 4 months. Her lifetime production was 40,112 pounds
of milk.
Although the second cow had been considered the poorer cow,
based on first lactation, her shorter calving intervals resulted in
two more calves and 4,970 pounds more milk than the first cow.

MAINTAINING NUMBERS IN THE DAIRY HERD
What proportion of females needs to be raised as replace-
ments to maintain a dairy herd?
A separate study of this problem was made of reproduction
during a 21-year period in the Station dairy herd. The repro-
ductive histories of 249 Jersey cows showed 919 calves at single
births, 450 of which were heifers. Among 16 pairs of twins
were three pairs of females and six freemartin heifers. Includ-
ing the twins, there were 1.86 females per reproductive life
of the average cow. The program during those years was to
raise all heifer calves that survive and reproduced. It was
found that 65.2 percent of the heifers born entered the milking
herd. This is an average of 1.21 females per dam.
If the object is to maintain the herd at the same size, the
above records indicate that 82 percent of all heifers would need
to have been selected, in order that 65 percent would freshen
eventually. If the object is to increase the size of the herd,
the operator would be able to increase the herd about 20 percent
annually by saving all female calves dropped. This wcald allow
increase but prevent improvement of the herd through election
and culling less desirable animals.







36 Florida Agricultural Experiment Stations

DISCUSSION AND CONCLUSIONS
Several points on dairy cattle breeding have been studied and
assembled as they relate to operations under control of the
owner or herd manager. Commercial dairy herds consist of
cows that were selected or remained after less desirable animals
had been removed. Therefore, the average ability is above the
true hereditary capacity of all cows. A proportion of cull animals
will continue to be born in every generation. Early recognition
and disposal of the less satisfactory individuals will tend to re-
duce the proportion of undesirable animals and/or families in
a breeding herd in future generations.
Extensive use of bulls proved desirable by sampling and raising
replacements from satisfactory cows out of good families are
the primary means of achieving high productivity in the dairy
herd. Keeping complete records of individual animals and mak-
ing continuous constructive use of them are the means whereby
the breeder can accomplish this goal.

ACKNOWLEDGMENTS
John M. Scott developed the original Station Jersey herd at Gaines-
ville and accumulated earlier records. Frank X. Brenneis, Charles R.
Dawson, Clarence Robinson, Burdette Schee, Hermon Somers and many
student assistants helped with the animals and records used in this study
of building a dairy herd.





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