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Group Title: Bulletin - University of Florida Agricultural Experiment Station ; no. 540
Title: Productive life-span of dairy cattle
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027093/00001
 Material Information
Title: Productive life-span of dairy cattle
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Alternate Title: Productive life span of dairy cattle
Physical Description: 18 p. : ; 23 cm.
Language: English
Creator: Becker, R. B ( Raymond Brown ), 1892-1989
Arnold, P. T. Dix, 1902-
Spurlock, A. H
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1954
 Subjects
Subject: Dairy cattle   ( lcsh )
Livestock productivity   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: R.B. Becker and P.T. Dix Arnold and A.H. Spurlock.
General Note: Cover title.
Funding: Bulletin (University of Florida. Agricultural Experiment Station) ;
 Record Information
Bibliographic ID: UF00027093
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000926384
oclc - 18276338
notis - AEN7055

Table of Contents
    Title Page
        Page 1
        Page 2
        Page 3
    Table of Contents
        Page 4
    Main
        Page 5
        Page 6
    Useful life-span of dairy cows
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
Full Text



Bulletin 540


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
WILLARD M. FIFIELD, Director
GAINESVILLE, FLORIDA












Productive Life-Span of Dairy Cattle




R. B. BECKER and P. T. DIX ARNOLD
Dairy Science Department
and
A. H. SPURLOCK
Agricultural Economics Department


Single copies free to Florida residents upon request to
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA


March 1954











BOARD OF CONTROL
Hollis Rinehart, Chairman, Miami
J. Lee Ballard, St. Petersburg
Fred H. Kent, Jacksonville
Wm. H. Dial, Orlando
Mrs. Alfred 1. duPont, Jacksonville
George W. English, Jr., Ft. Lauderdale
W. Glenn Miller, Monticello
W. F. Powers, Secretary, Tallahassee
EXECUTIVE STAFF
John S. Allen, Actines President '
J. Wayne Reitz, Ph.D., Provost for Agr.3
Willard M. Filield, M.S., Director
J. R. Beckenbach, Ph.D., Asso. Director
L. O. Gratz, Ph.D., Assistant Director
Rogers L. Bartley, B.S., Admin. Mgr.3
Geo. R. Freeman, B.S., Farm Superintendent

MAIN STATION, GAINESVILLE
AGRICULTURAL ECONOMICS
H. G. Hamilton, Ph.D., Agr. Economist
R. E. L. Greene, Ph.D., Agr. Economist3
M. A. Brooker, Ph.D., Agr. Economists
Zich Savage, M.S.A., Associate
A. H. Spurlock, M.S.A., Agr. Economist
D. E. Alleger, M.S., Associate
D. L. Brooke, M.S.A., Associate
M. R. Godwin, Ph.D., Associate:
W. K. McPherson, M.S., Agr. Economist
Eric Thor, S., Asso. Agr. Economist E
Cecil N. Smith, M.A., Asso. Agr. Economist
Levi A. Powell, Sr., M.S.A., Assistant *
E. D. Smith, Ph.D., Asst. Agr. Economist
N. K. Roberts, M.A., Asst. Agr. Economist
Orlando, Florida (Cooperative USDA)
G. Norman Rose, B.S., Asso. Agri. Economist
J. C. Townsend, Jr., B.S.A., Agr. Statistician2
J. B. Owens, B.S.A., Agr. Statistician 2
F. T. Calioway, M.S., Agr. Statistician
C. L. Crenshaw, M.S., Asst. Agr. Economist
B. W. Kelly, M.S., Asst. Agr. Economist
AGRICULTURAL ENGINEERING
Frazier Rogers, M.S.A., Agr. Engineer'3
J. M. Myers, M.S.A., Asso. Agr. Engineer
J. S. Norton, M.S., Asst. Agr. Engineer
AGRONOMY
Fred H. Hull, Ph.D., Agronomist
G. B. Killinger, Ph.D., Agronomist
H. C. Harris, Ph.D., Agronomist
R. W. Bledsoe, Ph.D., Agronomist
W. A. Carver, Ph.D., Agronomist
Fred A. Clark, M.S., Associate
E. S. Horner, Ph.D., Assistant
A. T. Wallace. Ph.D., Assistant
A. E. McCloud, Ph.D., Assistant s
G. C. Nutter, Ph.D., Asst. Agronomist
I. M. Wofforl, Ph.D., Asst. Agrnonom:st
E. 0. Burt, Ph.D., Asst. Agronomist
J. W. Edwardson, M.S., Asst. Agronomist 3
ANIMAL HUSBANDRY AND NUTRITION
T. J. Cunha, Ph.D., Animal Husbandman'
G. K. Davis, Ph.D., Animal Nutritionist
R. L. Shirley, Ph.D., Biochemist
A. M. Pearson, Ph.D., Asso. An. Hush.3
John P. Feaster, Ph.D., Asst. An. Nutri.
H. D. Willace, Ph.D., Asso. An. Husb.
M. Koger, Ph.D., An. H'usbandman 3
J. F. Hentges, Jr., Ph.D., Asst. An. Husb.
L. R. Arrrl.sfn Ph.YD., Asst. An. Hush.
A. C. ..... I Ph.D., Asst. Physiologist

DAIRY SCIENCE
E. L. Pouts, Ph.D., Dairy Technologist' 3
R. IB. Becker, Ph.D., Dairy Husbandman u
S. P. Marshall, Ph.D., Asso. Dairy Husb.:l
W. A. lKrienke, M.S., Asso. Dairy Tech.:
P. T. Dix Arnold, M.S.A., Asso. Dairy Husb. :
Leon Mull, Ph.D., Asso. Dairy Tech.:
H. H. Wilkowske, Ph.D., Asst. Dairy Tech.3
James M. Wing, Ph.D., Asst. Dairy Hush.


EDITORIAL
J. Francis Cooper, M.S.A., Editor
Clyde Beale, A.B.J., Associate Editor
William G. Mitchell, A.B.J., Assistant Editor
Samuel L. Burgess, A.B.J., Assistant Editor

ENTOMOLOGY
A. N. Tissot, Ph.D., Entomologist'
L. C. Kuitert, Ph.D., Associate
H. E. Bratley, M.S.A., Assistant
F. A. Robinson, M.S., Asst. Apiculturist
R. E. Waites, Ph.D., Asst. Entomologist
S. H. Kerr, Ph.D., Asst. Entomolosist
,1. H. Christie, Ph.D., Nematologist

HOME ECONOMICS
Ouida D. Abbott, Ph.D., Home Econ.'
R. B. French, Ph.D., Biochemist

HORTICULTURE
G. H. Blackmon, M.S.A., Horticulturist 1
R. A. Dennison, Ph.D., Hort. & Interim Head
F .Jamison, Ph.D., Horticulturist2
Albert P. Lorz, Ph.D., Horticulturist
R. K. Showalter, M.S., Asso. Hort.
R. H. Sharpe, M.S., Asso. Horticulturist
V. F. Nettles, Ph.D., Asso. Horticulturist
F. S. Lagasse, Ph.D., Horticulturist
I. D. Dickey, M.S.A., Asso. Short.
L. H. Halsey, M.S.A., Asst. Horl.
C. B. Hall, Ph.D., Asst. Horticulturist
Austin Griffiths Jr., B.S., Asst. Hort.
S. E. McFadden, Jr., Ph.D., Asst. Hort.
C. H. VanMiddelem, Ph.D., Asst. Biochemist
B. D. Thompson, M.S.A., Interi Asst. Hort.
M. W. Hoover, M.S.A., Asst. Hort.
LIBRARY
Ida Keeling Cresap, Librarian

PLANT PATHOLOGY
W. B. Tisdale, Ph.D., Plant Pathologist s
Phares Decker, Ph.D., Plant Pathologist
Erdman West, M.S., Botanist & Mycologist
Robert W. Earhart, Ph.D., Plant Path.2
Howard N. Miller, Ph.D., Asso. Plant Path.
Lillian E. Arnold, M.S., Asso. Botanist
C. W. Anderson, Ph.D., Asst. Plant Path.
POULTRY HUSBANDRY
N. R. Mehrhof, M.Agr., Poultry Hush.' :
J. C. Driggers, Ph.D., Asso. Poultry Husb.'

SOILS
F. B. Smith, Ph.D., Microbiologis't 1
Gaylord M. Volk, Ph.D., Soils Chemist
J. R. Neller, Ph.D., Soils Chemist
Nathan Gammon, Jr., Ph.D., Soils Chemist
Ralph G. Leighty, B.S., Asst. Soil Surveyor a
G D. .Thornton, Ph.D., Microbiologist
C. F. Eno, Ph.D., Asst. Soils Microbiologist
H. W. Winsor, B.S.A., Assistant Chemist
R. E. Caldwell, M.S.A., Asst. Chemist 5
V. W. Carlisle, B.S., Asst. Soil Surveyor
J. H. Walker, M.S.A., Asst. Soil Surveyor
William K. Robertson, Ph.D., Asst. Chemist
0. E. Cruz, B.S.A., Asst. Soil Surveyor
W. G. Blue, Ph.D., Asst. Biochemist
J. G. A. F'iskel, Ph.D., Asst. Biochemist
L. C. Hammond, Ph.D., Asst. Soil Physicist
H. L. Breland, Ph.D., Asst. Soils Chem.
W. L. Pritchett, Ph.D., Soil Technologist

VETERINARY SCIENCE
D. A. Sanders, D.V.M., Veterinarian 13
M. W. Emmel, D.V.M., Veterinarian :
C. F. Simpson, D.V.M., Asso. Veterinarian
L. E. Swanson, D.V.M., Parasitologist
W. R. Dennis, D.V.M., Asst. 'Parasitologist
E. W. Swarthout, D.V.M., Asso. Poultry
Pathologist (Dade City)
M. Ristic, D.V.M., Asso. Poultry Pathologist










BRANCH STATIONS

NORTH FLORIDA STATION, QUINCY
D. S. Prosser, Jr., B.S., Asst. Engineer
W. C. Rhoades, M S., Entomologist in Charge
R. R. Kincaid, Ph.D., Plant Pathologist
L. G. Thompson, Jr., Ph.D., Soils Chemist
W. H. Chapman, M.S.. Agronomist
Frank S. Baker, Jr., B.S., Asst. An. Husb.
Frank E. Guthrie, Ph.D., Asst. Entomologist
Mobile Unit, Monticello
R. W. Wallace, B.S., Associate Agronomist
Mobile Unit, Marianna
R. W. Lipscomb, M.S., Associate Agronomist
Mobile Unit, Pensacola
R. L. Smith, M.S., Associate Agronomist
Mobile Unit, Chipley
J. B. White, B.S.A., Associate Agronomist


CITRUS STATION, LAKE ALFRED

A. F. Camp, Ph.D., Vice-Director in Charge
W. L. Thompson, B.S., Entomnlogist
R. F. Suit, Ph.D., Plant Pathologist
E. P. Ducharme, Ph.D., Asso. Plant Path.
J. W. Sites, Ph.D., Horticulturist
H. O. Sterling, B.S., Asst. Horticulturist
H. J. Reitz, Ph.D., Horticulturist
Francine Fisher, M.S., Asst. Plant Path.
I. W. Wander, Ph.D., Soils Chemist
J. W. Kesterson, M.S., Asso. Chemist
R. Hendrickson, B.S., Asst. Chemist
ivan Stewart, Ph.D., Asst. Biochemist
R. W. Olscn, B.S., Biochemist
F'. W .Wenzel, Jr., Ph.D., Chemist
Alvin H. Rouse, M.S., Asso. Chemist
H. W. Ford, Ph.D., Asst. Horticulturist
I.. C. Knorr, Ph.D., Aaso. Hiiitologi t
R. M. Pratt, Ph.D., Asso. Ent.-Pathologist
W. A. Simanton, Ph.D., Entomologist
E. J. Deszyck, Ph.D., Asso. Horticulturist
C. DY. Leonard, Ph.D., Asso. Horticulturist
W. T. Long, M.S., Asst. Horticulturist
M. H. Muma, Ph.D., Asso. Entomologist
F. J. Reynolds, Ph.D., Asso. Hort.
W. F. Spencer, Ph.D., Asst. Chem.
R. B. Johnson, Ph.D., Asst. Entomologist
W. F. Newhall, Ph.D., Asst. Biochemist
W. F. Grierson-Jackson, Ph.D., Asst. Chem.
Roger Patrick, Ph.D., Bacteriologist
M. F. Oberbacher, Ph.D., Asst. Plant Physiol.
Evert J. Elvin, B.S., Asst. Horticulturist
R. C. J. Koo, Ph.D., Asst. Biochemist
J. R. Kuykendall, Ph.D., Asst. Horticulturist
W. C. Price, Ph.D., Virologist


EVERGLADES STATION, BELLE GLADE
W. T. Forsee, Jr., Ph.D., Chemist in Charge
R. V. Allison, Ph.D., Fiber Technologist
Thomas Bregger, Ph.D., Physiologist
J. W. Randolph, M.S., Agricultural Engr.
R. W. Kidder, M.S., Asso. Animal Hush.
C. C. Seale, Associate Agronomist
N. C. Hayslip, B.S.A. Asso. Entomologist
E. A. Wolf, M.S., Asst. Horticulturist
W. H. Thames, M.S., Asst. Entomologist
W. G. Genung, M.S., Asst. Entomologist
Robert J. Allen, Ph.D., Asst. Agronomist
V. E. Green, Ph.D., Asst. Agronomist
J. F. Darby, Ph.D., Asst. Plant Path.
V. L. Guzman, Ph.D., Asst. Hort.
J. C. Stephens, B.S., Drainage Engineer-
A. E. Kretschmer, Jr., Ph.D., Asst. Soils
Chem.
Charles T. Ozaki, Ph.D., Asst. Chemist
Thomas L. Meade, Ph.D., Asst. An. Nutri.
U. S. Harrison. M.S., Asst. Agri. Engr.
F. T. Boyd, Ph.D., Asso Agronomist


M. G. Hamilton, Ph.D., Asst. Horticulturist
J. N. Simons, Ph.D., Asst. Virologist
D. W. Beardsley, M.S., Asst. Animal Hush.
R. S. Cox. Ph.D., Asso. Plant Pathologist

SUB-TROPICAL STATION, HOMESTEAD
Geo. D. Ruehle, Ph.D., Vice-Dir. in Charge
D. O. Wolfenbarger, Ph.D., Entomologist
Francis B. Lincoln, Ph.D., Horticulturist
Robert A. Conover, Ph.D., Plant Path.
John L. Malcolm, Ph.D., Asso. Soils Chemist
R. W. Harkness, Ph.D., Asst. Chemist
R, Bruce Ledin, Ph.D., Asst. Hort.
J. C. Noonan, M.S., Asst. Hort.
M. H. Gallatin. B.S., Soil Conservationist2
T. W. Youne, Ph.D., Asso. Horticulturist

WEST CENTRAL FLORIDA STATION,
BROOKSVILLE
Marian W. Hazen, M.S., Animal Husband-
man in Charge2

RANGE CATTLE STATION, ONA
W. G. Kirk, Ph.D., Vice-Director in Charge
E. M. Hodges, Ph.D., Agronomist
D. W. Jones, M.S., Asst. Soil Technologist

CENTRAL FLORIDA STATION, SANFORD
R. W. Ruprecht, Ph.D., Vice-Dir. in Charge
J. W. Wilson, ScD., Entomologist
P. J. Westgate, Ph.D., Asso. Hort.
Ben F. Whitner, Jr., B.S.A., Asst. Hort.

WEST FLORIDA STATION, JAY
C. E. Hutton, Ph.D., Vice-Director in Charge
H. W. Lundy, B.S.A., Associate Agronomist
R. T. Jeflfer-. Ph.D., A ,o. Auronomist

SUWANNEE VALLEY STATION,
LIVE OAK
G. E. Ritchey, M.S., Agronomist in Charge

GULF COAST STATION, BRADENTON
E. L. Spencer, Ph.D., Soils Chemist in Charge
E. G. Kelsheimer, Ph.D., Entomologist
David G. A. Kelbert, Asso. Horticulturist
Robert O. Magie, Ph.D., Plant Pathologist
J. 31. Walter, Ph.D., Plant Pathologist
S. S. Woltz, Ph D., Asst. Horticulturist
Donald S. Burgis, M.S.A., Asst. Hort.
C. M. Geraldson, Ph.D., Asst. Horticulturist
G. Sowell. Jr.. Ph.D., Asst. Plant Pathologist


FIELD LABORATORIES

Watermelon, Grape, Pasture-Leesburg
J. M. Crall, Ph.D., Asso. Plant Path. in Chg.
C. C. Helms, Jr., B.S., Asst. Agronomist
L. H. Stover, Assistant in Horticulture
Strawberry-Plant City
A. N. Brooks, Ph.D., Plant Pathologist
Vegetables-Hastings
A. H. Eddins, Ph.D., Plant Path. in Charge
E. N. McCubbin, Ph.D., Horticulturist
T. M. Dobrovsky, Ph.D., Asst. Entomologist
D. I. ylvhre, B S.. A Pecans-Monticello
A. M1. Phillips, B.S., Asso. Entomologist2
John R. Large, M.S., Asso. Plant Path.
Frost Forecasting-Lakeland
Warren O. Johnson, B.S., Meteorologist in
Charge

1 Head of Department
2 In cooperation with U. S.
SCooperative, other divisions, U. of F.
4 On leave
















CONTENTS






INTRODUCTION


SOURCES AND USES OF RECORDS .


USEFUL LIFE-SPAN OF DAIRY COWS


TURNOVER OF COWS IN FLORIDA DAIRY HERDS


EARLY TURNOVER OF DAIRY BULLS IN NATURAL SERVICE


TURNOVER OF DESIRABLE DAIRY BULLS IN NATURAL SERVICE ...


LIFE-EXPECTANCY OF DESIRABLE BULLS IN NATURAL SERVICE


TURNOVER AND LIFE-EXPECTANCY OF DESIRABLE BULLS IN ARTIFICIAL

SERVICE


DISCUSSION .... ............


SUMMARY AND CONCLUSIONS ...


ACKNOWLEDGMENTS








Productive Life-Span of Dairy Cattle

R. B. BECKER, P. T. DIX ARNOLD and A. H. SPURLOCK

INTRODUCTION
It usually takes one to three years of milk production for a
good-producing dairy cow to repay her cost of raising. The
time varies with feed and labor costs, milk yield, and market
value of milk. Most cows should have paid for themselves
when three to five years old. Beyond that age, income from
sale of milk above all other costs accrues to the benefit of the
owner. Hence, a long productive lifetime is desirable in dairy
cattle.
Annual depreciation in value of dairy cows ranks, after feed
and labor, as the third largest item in cost of milk production.
Long productive life of a dairy cow reduces annual deprecia-
tion by spreading the cost of raising over more years.
Investigations are being conducted to determine the aver-
age useful life-span and reasons for disposal of cattle from
dairy herds. Such information may enable a herdsman to im-
prove management and sanitation and use veterinary care when
needed to avoid or reduce loss from some causes. This pro-
gress report presents facts now assembled and indicates some
measures which might prolong useful life.

SOURCES AND USES OF RECORDS
The average tenure of cows in Florida dairies has been de-
termined by two methods: (a) surveys of 101 commercial
herds, many of which were maintained by purchasing replace-
ments, and (b) continuing cooperation with 14 herds located
widely over the state, using individual records of cows of
known ages. The latter group included grade and purebred
cattle of three major dairy breeds-Guernsey, Holstein, and
Jersey. Dates and reasons for disposal were obtained from the
records of these cooperating herd owners.
Records of dairy bulls were secured by correspondence and
visits from owners in United States and Canada. Also, na-
tional breed registry associations contributed facts concern-
ing many bulls. Reasons for death or disposal presented are
owners' statements, often based on veterinary diagnoses. Termi-
nation of useful life of a bull was based on the date of final







Florida Agricultural Experiment Stations


conception from his use. Bulls discarded while yet usable were
considered separately from those completing their natural use-
ful life. A life expectancy table was computed, based on bulls
that completed their natural useful life.
A large number of artificial breeding organizations are co-
operating by submitting their records of past and present bulls.

USEFUL LIFE-SPAN OF DAIRY COWS

In surveying 101 commercial dairy herds in six major Florida
milksheds for 1950, it was found that the average productive
life of dairy cows in milking herds, maintained largely by
purchased replacements, was 3.9 years after entering the herd.1
Birth dates of these cows were not obtained, and some animals
were purchased as milking cows.


percent
100


2 3 54 6 7 8 9 10 11
Age (years)
Fig. 1.-Cows remaining in the herd at various ages.


The calculated productive life-span for the dairy cows in the
cooperating Florida herds that were maintained largely with
home-raised replacements was 4.7 years, assuming that they
entered the milking herd at about two years of age. The longer

SRecomputed for 101 herds surveyed in "Cost of Producing Milk in
Selected Areas of Florida," A. H. Spurlock, D. L. Brooke and R. E. L.
Greene. Fla. Agr. Exp. Sta. Agr. Econ. Series 51-4. 1951.







Florida Agricultural Experiment Stations


conception from his use. Bulls discarded while yet usable were
considered separately from those completing their natural use-
ful life. A life expectancy table was computed, based on bulls
that completed their natural useful life.
A large number of artificial breeding organizations are co-
operating by submitting their records of past and present bulls.

USEFUL LIFE-SPAN OF DAIRY COWS

In surveying 101 commercial dairy herds in six major Florida
milksheds for 1950, it was found that the average productive
life of dairy cows in milking herds, maintained largely by
purchased replacements, was 3.9 years after entering the herd.1
Birth dates of these cows were not obtained, and some animals
were purchased as milking cows.


percent
100


2 3 54 6 7 8 9 10 11
Age (years)
Fig. 1.-Cows remaining in the herd at various ages.


The calculated productive life-span for the dairy cows in the
cooperating Florida herds that were maintained largely with
home-raised replacements was 4.7 years, assuming that they
entered the milking herd at about two years of age. The longer

SRecomputed for 101 herds surveyed in "Cost of Producing Milk in
Selected Areas of Florida," A. H. Spurlock, D. L. Brooke and R. E. L.
Greene. Fla. Agr. Exp. Sta. Agr. Econ. Series 51-4. 1951.







Productive Life-Span of Dairy Cattle


tenure of home-raised cows in the milking herds was regarded
as important economically.
The average useful life-span in Florida dairies (Fig. 1) was
based upon individual records of cows that had been removed
from the 14 cooperating herds. They included cows that died
or were disposed of after they were no longer desirable in the
herds. Records of cows sold for dairy purposes were excluded.
These records are given in Table 1.

TABLE 1.-AVERAGE USEFUL LIFE-SPAN OF 1,742 FLORIDA DAIRY Cows-ALL
BREEDS (EXCLUDES COWS SOLD FOR DAIRY OR BREEDING PURPOSES, AND
THosE NOT Two YEARS OF AGE).

Number of Cows Average Anticipated
Age Percent Left Herd Age at Usefulness at
Living : of Total During Yr. Disposal Different Ages
S(Number) (Percent) (Number) (Years) (Years)
2 1,742 100.0 107 6.7 4.7
3 1,635 93.9 219 7.0 4.0
4 1,416 81.3 236 7.5 3.5
5 1.180 67.7 248 8.2 3.2
; 932 53.5 192 8.9 2.9
7 740 42.5 186 9.5 2.5
8 554 31.8 184 10.2 2.2
9 370 21.2 117 11.1 2.1
10 253 14.5 91 11.9 1.9
11 162 9.3 59 12.8 1.8
12 103 5.9 45 13.5 1.5
13** 58 3.3 29 14.4 1.4
14** 29 1.7 11 15.5 1.5
15** 18 1.0 8 16.3 1.3
16* 10 .6 7 17.0 1.0
17** 3 .2 0
18' '3 .2 2 18.4 .4
19* 1 .1 1 19.2 .2

Of 1,742 original animals as two-year-olds, 107 left the herd during the year and
1,635 remained as three-year-old cows. and so on consecutively.
** Insufficient numbers to be reliable.

TURNOVER OF COWS IN FLORIDA DAIRY HERDS

The causes of deaths or reasons for disposal of dairy cows
in the 14 dairy herds have been analysed for 2,182 cows so
removed. These are tabulated in Table 2. Animals sold for
milking purposes have been excluded from this analysis.
Udder troubles, including mastitis, were the major causes of
removing cows from the herd. Low production and reproductive
troubles ranked as the second and third major causes. Fifty-
eight percent of the losses came from one or more of these
causes. Some of the cows leaving the herds for reasons un-








Florida Agricultural Experimentc Stations


stated may add to this 58 percent. If such conditions can be
reduced through skillful management, the average useful life
of cows can be extended.

TABLE 2.-PRINCIPAL REASONS FOR DISPOSAL OF 2,182 FLORIDA DAIRY COWS,
AS GIVEN BY DAIRYMEN. (EXCLUDES COWS SOLD FOR DAIRY OR BREEDING
PURPOSES AND THOSE NOT REACHING TWO YEARS OF AGE.)

Reason for Disposal iNumber of Cows Percent of Total


Mastitis and udder trouble ... 464 21.3
Low production .............. .... ...... 410 18.8
Reproductive troubles ..... .... 276 12.7
Combinations of above ....... 114 5.2
Diseases ........................................ 85 3.9
O ld age .. .... .... .... .. ...... .... .. 70 3.2
Accidents and injuries ......... 49 2.2
Other reasons ....................... 38 1.7
Unstated ............................. 367 16.8
Total disposals before death ...... 1,873 85.8
Death:
Disease:
Johne's ........................... 22
Milk fever .......... ........... 20
Mastitis and udder ........... 19
Anaplasmosis ....................... 16
Acetonemia ................... ..... 12
Other diseases ............................ 33
Total deaths from disease ......... 122 5.6
Reproductive troubles .................... 44 2.0
Accidental death, poisoning' .......... 39 1.8
Old age .......... ..... ... .. ....... .. 14 .6
Other causes .. ............ ............ 47 2.2
Unknown causes ................. 43 2.0
Total deaths ................ 309 14.2

Total .......... ...... .... ... .... 2,182 100.0


Death caused the loss of 14.2 percent of the total cows. Of
these, almost 40 percent were attributed to various diseases,
the leading of which were Johne's disease, milk fever, mastitis
and udder complications, anaplasmosis and acetonemia. A few
deaths were caused by pneumonia. Reproductive troubles caused
14 percent of the deaths; accidents and poisoning caused 12.6
percent. The accidents were caused by falls, electrocution, and
injuries from foreign bodies, such as wire, nails, etc. Poisoning
was caused by eating toxic plants or licking lead paint or fer-
tilizer materials.






Productive Life-Span ot Dairy Cattle


The price of a cow salvaged for beef will not pay the cost
of raising or buying a suitable replacement. Cows discarded
from the herds were salvaged for beef. Reasons for the dis-
posals and for deaths are given in Table 2. It is desirable to
extend the profitable useful life of a good dairy cow by every
reasonable means at the dairyman's disposal.

EARLY TURNOVER OF DAIRY BULLS IN
NATURAL SERVICE
Though bulls are a small proportion of the cattle in a dairy
herd, they equal cows in determining the herd's future heredi-
tary capacity. Hence, transmitting ability of bulls should be
determined at the youngest possible age. Bulls siring unsatis-
factory daughters need to be recognized and discarded early.
When desirable bulls are proved by five to six years of age they
should be retained for maximum subsequent use. Many herds
are too small to keep more than one bull at a time. Joint or
cooperative ownership could enable continued use of sires that
prove desirable. Expansion of artificial breeding has created
considerable demand for the better proved bulls.
Why are bulls eliminated from herds at early ages?
An analysis of the reasons for early disposal of 2,254 dairy
bulls of five breeds is given in Table 3. Records were obtained
from herd owners in nearly every state and Canadian province
and are believed to represent fairly the dairy cattle industry.
The main reason for short tenure of bulls in small herds was
to avoid inbreeding. Owners gave this as the reason for dis-
carding 34.5 percent of these 2,254 bulls. Some of them had
been used in two, three or possibly more herds. (Some de-
sirable Guernsey bulls were in natural service on as many as
seven successive farms.) These purebred bulls were from
purebred and grade dairy herds widely distributed over the
United States and Canada.
Lack of a safety bull pen or other safe method of handling
bulls was mentioned specifically as the reason for early dis-
posal of some bulls. Bad disposition caused 14.1 percent dis-
posal. An economical safety breeding chute that can be built
in most bull pens is described in Florida Station bulletin 464,
Management of Dairy Cattle in Florida.
Low production of daughters was the reason for discarding
235 bulls. Some of them had been sampled and held pending
proof.








Florida Agricultural Experiment Stations


TABLE 3.-REASONS GIVEN BY OWNERS FOR DISPOSAL OF DAIRY BULLS
WHILE YET USABLE.

Reason for Numbers Discarded at Various Ages Per-
Disposal 1-3 4-5 6-8 9-10 11-14 Total centage
Yrs. Yrs. Yrs. Yrs. Yrs. of Bulls

Avoid inbreeding 112 255 279 1 00 31 777 34.5
Disposition ... 64 130 95 22 ( 317 14.1
Low production 9 77* 119 24 (; 235 10.4
Poor type pro-
geny** ........ 32 47 54 18 3 154 6.8
Other bull pre-
ferred ........... 27 27 65 20 3 143 6.4
Slow breeder ... 22 23 28 9 2 84 3.7
Herd reduction 8 11 21 11 51 2,3
Transmitted low
fat test ......... 1* 10* 13 2 1 27 1.2
Bull too large 4 9 9 3 25 1.1
Poor type bull .... 17 2 2 21 1.0
Changed to arti-
ficial breeding 4 3 2 3 1 13 0.6
Changed breeds 4 1 5 0.2
Reason not
stated ......... 47 132 156 55 9 399 17.7


Total ............ 347 732 845 267 63 2,254 100.0

*A number of these bulls had been sampled and held pending proof by daughter-dam
comparisons.
** Poor udders or weak udder attachments on daughters were mentioned for many of
these bulls.

TURNOVER OF DESIRABLE DAIRY BULLS IN
NATURAL SERVICE

Turnover of desirable dairy bulls in natural use was attrib-
uted by owners and herd managers to some 65 or more causes,
based on reports of 5,177 animals received to date. These
causes divide into two categories-non-infectious and infectious,
with far larger numbers in the first category. Well over one-
fourth of the animals were used until onset of sterility from
various causes. Over 11 percent of bulls died, and the cause
was not diagnosed specifically or not mentioned. Accidents and
injuries accounted for an additional 10 percent. Inability to
serve, or low fertility (low conception rate, or poor semen qual-
ity), accounted for 8.8 percent, while the inroads of advancing
age took nearly the same proportion.
Vigilant owners or herdsmen endeavor to keep pieces of bal-
ing wire, nails or other metal out of feed. Nevertheless, over
5.3 percent of bulls died or were salvaged because of foreign







Productlice Life-Span ot Dairy Cattle


bodies in the stomach. Close proximity of the reticulum to
heart, lungs and liver makes accidental puncture of the wall
of this stomach compartment by sharp metal objects an ever-
present hazard. Where individual attention was given to feed-
ing each bull in the artificial studs the losses from foreign
bodies (metal) were 3.04 percent.
Lamness and bad feet and legs necessitated disposal of five
percent of bulls. Sometimes this occurs from neglecting to trim
the hoofs or to provide exercise that will wear them off nat-
urally. Overgrown toes throw the feet and pasterns out of
normal position and may weaken a heavy animal so as to pre-
vent his use. Exercise on a fine gravel, concrete or cinder
walkway, or regular trimming of hoofs at three- to six-month
intervals, helps prevent loss of usefulness. Sprains and in-
juries to the stifle joint also occurred.
Bloat was among digestive disorders causing loss of some
bulls. It cannot be eliminated entirely, although it occurs less
frequently among cattle that (a) have access to some dry hay
(grass hays preferred) and (b) are not hungry when turned
onto lush leguminous pastures.
Lead paint that is not flinty-dry has been licked sufficiently
to cause lead poisoning and death. Poisonous plants, wood pre-
servatives, nitrate fertilizers and some other toxic substances
also were among miscellaneous causes of deaths. These may
be guarded against.
Lumpy jaw actinomycosiss) was highest among infectious
causes of losses among dairy bulls. It has been known for over
50 years 2 that this disease is caused by a fungus. Entrance is
gained through an abrasion of the skin or mucous membrane of
the mouth. At first, only a lump is noticeable at point of in-
fection. The fungus grows, attacks and even destroys parts of
the bone. The infection is scattered when the abscess bursts
and spreads pus onto halters, stalls, feed mangers, water troughs
and surroundings. If detected early, the enlargement may be
removed surgically or treated medicinally. No cure is known
for advanced stages. The condition should be regarded with
alarm in the pus-spreading stage, as it is communicable to man.
Thorough cleaning of stalls and disinfection of all surroundings
with boiling hot lye solution can reduce future hazard after dis-
posal of the animal.

U. S. Dept. Apr. Bur. An. Ind. Bul. 2: 7-90. 1893.








Florida Agricultural Experiment Stations


Few losses from tuberculosis were reported recently. Losses
from brucellosis and Johne's disease are declining through eradi-
cation campaigns. Some abscesses were initiated by bruises or
injuries (as from foreign bodies). Pneumonia also is secondary,
often following lowering of resistance due to other causes.
Trichomoniasis can be checked from spreading by following
recommended sanitary measures.
Losses of bulls in natural service from infectious causes
amounted to 15.2 percent of the total number studied. This
was higher in proportion, however, than the losses among bulls
in artificial service. Closer attention is given to animals in the
breeding units, and diagnostic tests often are applied before
purchase.
Reasons for elimination of desirable bulls from natural serv-
ice are given in Table 4.

TABLE 4.-REASONS FOR DISPOSAL OR CAUSES OF DEATHS OF DESIRABLE
BULLS IN NATURAL SERVICE.

Proportion of
Termination of Use Number Total Number
Attributed to: of Bulls (Percent)

Mainly non-infectious causes:
Sterility ......................... .. 1,496 28.90
Undiagnosed deaths ........... 602 11.63
Accidents, injuries, etc. .... 514 9.93
Low fertility, inability .... 459 8.87
Senility .......... ........... 455 8.79
Wire, nails, etc .........- 27(; 5.33
Lameness, bad feet and
legs ......... ............ 263 5.08
Digestive diseases ........... 111 2.14
Paralysis .......................... 71 1.37
Other non-infectious
causes ....................... 140 2.70
Causes largely infectious: Percent
Lumpy jaw (actino-
mycosis) ............ ... 191 3.69
Tuberculosis, Johne's
disease ..................... 86 1.66
Pneumonia ......................... 82 1.58
Tumors, abscesses .......... 81 1.57
Trichomoniasis ......... ... 79 1.53
Brucellosis ....................... 78 1.51
Kidney and bladder
conditions ................ 53 1.02
Diseases of reproductive
tract ............................. 43 0.83
Miscellaneous infectious
causes ......................... 97 1.87
Total from infectious causes 15.26


5,177


Total


100.00







Productive Life-Span of Dairy Cattle


LIFE EXPECTANCY OF BULLS IN NATURAL SERVICE

A dairy bull is five years old or more before his desirability
can be determined by comparison of the production of daugh-
ters with that of their dams. Hence, a life-expectancy table ap-
plicable to bulls that prove desirable should begin at five years
of age. Since some bulls born during 1937 still were in active
use, it was necessary to limit a life-expectancy table to bulls
born prior to 1937. This avoids age distortion in computations.
The records of 3,895 bulls of five dairy breeds met the qualifi-
cations for use in such a table (Table 5).
Considering the useful life of these bulls from their fifth
birthdays to the date of last service resulting in conception,
the average age of the group was 10.43 years. At 10 years
of age 2,153 of them yet were in use, with 12.53 years being
their average. By their 14th birthdays 319 remained which
were useful to an average age of 15.14 years. Beyond this age
the numbers were too few for reliance to be placed on much
future usefulness. Only three of the original 3,895 animals
were in limited use at 19 years of age.
The anticipated useful life of any healthy bull in active use
can be estimated from the average time listed in the fourth
column of Table 5. The chances are about even (1:1) that he
will be usable for any period past a given birthday. Less con-

TABLE 5.-LIFE-EXPECTANCY OF DESIRABLE BULLS THAT WERE USED THEIR
FULL LIFETIME IN NATURAL SERVICE (BORN BEFORE 1937).

Age of Number Average Age Average Anticipated
Group of Bulls" at Last Conception Useful Life
Years ....... Years 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
.5 131* 16.15 1.15**
16 58** 16.98 0.98**
17 22"* 17.86 0.86**
18 8** 18.79 0.79::::
19 3** 19.25 0.25**


*These cumulative totals leave out the number lost during,
** Too few animals for reliance on estimated future usefulness


each succeeding year.








Florida Agricultural Experiment Stations


fidence should be given these averages past the 13th birthday,
as the proportion surviving each following year is small.

TURNOVER AND LIFE-EXPECTANCY OF DESIRABLE
BULLS IN ARTIFICIAL SERVICE

Relatively few highly desirable proved bulls are available for
artificial service. This situation forced some breeding organiza-
tions to make limited use of young bulls selected from good cow
families and by good sires. Often these young bulls have been
sampled, leased out, or placed in reserve pending proof. Some
proved bulls have entered artificial service even when past 15
years of age. These are the extremes included in the bull
records in these analyses.

TABLE 6.-INITIAL AGE AND LENGTH OF ARTIFICIAL SERVICE OF 190
DESIRABLE BULLS BORN BEFORE 1937.


Age
at 1s
Arti-
ficial
Serv-
ice-

Yrs. 0-1
2
3
4 4
5 1
6 6
7 5
8 8
9 10
10 9
11 7
12 4
15


Number of Years in Artificial Service


1-2 2-3

1
a


13-4 4-5 5-6 6-7 17-8

1


I8-9 19-10
1

1 1
2 1
1


1 1


Animals


No. Percent

2 1.05
2 1.05
4 2.11
18 9.47
29 15.26
24 12.63
33 17.37
36 18.95
21 11.05
11 5.79
9 4.74
1 0.53


Total 54 38 32
Per-
cent-
age 28.4 20.0 16.9


18 16 12


7 5 5 2 1 1190


9.5 8.4 6.3 3.7 2.6 2.; 1.1 0.5


100.00


Some bulls failed to meet expectations and were discarded.
Semen of some animals was of unsatisfactory quality for ship-
ment. Others were withdrawn from service when leases termi-
nated, because better bulls became available or for comparable
reasons. Records of all such bulls were omitted, because they
were disposed of while still usable.






Productive Life-Span of Dairy Cattle


On June 30, 1953, 190 completed records were at hand of de-
sirable bulls born before 1937. At this age few individuals yet
were in service. Analysis of these records should enter little
age distortion into computations. Most of these 190 animals
had been bought or leased by the artificial breeding organiza-
tions as desirably proved. Their records are summarized in
Table 6.
These 190 bulls had an average useful period in artificial
service of 2.72 years. Analysis according to ages when in-
ducted into artificial use gives a clearer understanding of rate
of turnover. Over 28 percent were usable less than 12 months.
Another 55 percent lasted 1.0 to 4.9 years. Six percent were
used from 7.0 to 10.75 years. The extremes were a bull that
died suddenly after 14 days in use and a bull secured when 15
years old that was usable nearly 15 months longer. At least
one bull born before 1937 still was in artificial service, at last
information.
The length of artificial service of these desirable bulls is
listed according to tenure and ages at induction, in Table 6.
Of these 190 bulls 25 died; 151 were salvaged for beef; but no
reason was stated for disposal of 14 animals at advanced age.
To July 1953, 1,186 usable records were assembled of desir-
able bulls formerly in artificial use. Since some of them were
born as late as 1950, some age distortion is involved in their
analysis. They are presented only for the advantage gained
from larger numbers.
Bulls in commercial artificial use must produce calves or be
eliminated. Continual examinations of semen and scrutiny of
breeding reports permit early detection of low breeding effi-
ciency. Many organizations consider as low as 50 percent non-
returns from artificial breeding to be low efficiency. Others
have higher standards. Low breeding efficiency, sometimes
combined with other factors, was the leading cause of eliminat-
ing bulls. It amounted to 46 percent of the 1,186 bulls. Would
rest on pasture and exercise have restored some of them? A
proportion of these bulls might justify returning to lighter use
in natural service.
Total sterility, refusal to work artificially and low volume or
quality of semen terminated use of 14 percent of these bulls.
Accidents and injuries took 7.1 percent and old age nearly 4.0
percent. Further causes of turnover are listed in Table 7.








Florida Agricultural Experiment Stations


TABLE 7.-CAUSES OF ELIMINATION OF DESIRABLE DAIRY BULLS FROM
ARTIFICIAL SERVICE.


Low breeding efficiency ...............
Sterility, no semen ..... ....... .....
Low quality or volume of semen
Refusal to w ork ........... ......- -. ........
Accidents, injuries, rupture ............
Old age (senility) ........ .............
Lameness, rheumatism, bad feet and
legs ....... ........... .......... .
Foreign body (nails, wire, etc.) .
Cause not stated ....................
Cause of death undiagnosed
Digestive diseases, bloat ... .....
Poor physical condition ........ ..
P aralysis .................. .. ... .....
Other non-infectious causes ..........
Infectious causes:
Actinomycosis (lumpy jaw) ......
Brucellosis reactor ........... .
Tumors and abscesses ... .....
Pneum onia .................... .....
Other infectious causes .......


Total


Born Before
Jan., 1937

Number

70
20
9
7
12
23

(6
3
14
5

4

7

2
1
2
2
3


190


Total Completed
Records:
Per-
Number centage

556 46.88
751
25 4.25
691
84 7.08
47 3.96
4( 3.88
36 3.04
24 2.02
19 1.60
18
16 4.05
14
58 4.89


32
18
15
12
22


1,186


2.70
1.52
1.26
1.01
1.86


100.00


* Includes all records irrespective of birth dates.


DISCUSSION

What benefits can be gained from knowing causes of losses
of dairy animals?
Some diseases have been practically eliminated. Others have
been reduced when seriousness of the disease was realized and
measures applied for its eradication or control. Cattle tick
fever and tuberculosis have been practically eliminated. Brucel-
losis has been reduced and eventually may be eradicated.
With dairy cows improved methods of milking can reduce
udder troubles. Stimulation of let-down, carefully managed
milking and removal of teat cups when milking is completed
reduce the chances of udder injuries.
Some evidence points to exercise, regularity in use and good
feeding in maintaining fertility of bulls. Use of gravel, cinders
or concrete walkways may aid in regular wear of hoofs. Over-
grown hoofs may throw the feet and pasterns out of normal






Productive Life-Span of Dairy Cattle


position to the extent that a bull may be eliminated from use.
The most conspicuous improvement noted in recent visits to
artificial organizations has been the facilities for regular care
of hoofs.
It should be pointed out again that regular veterinary care of
bulls in the artificial units has held losses from infectious dis-
eases to a low proportion. Likewise, feeds that have passed
over electromagnets have reduced losses from foreign body in-
juries. More attention needs to be given to hay to remove any
loose wire. Any loose metal and nails need removal from sur-
roundings.
Reducing causes of loss will lengthen the useful life of cows
and bulls.
Lynn Copeland stated in The Jersey Bulletin recently: "While
early maturity has always been claimed as a desirable attribute
we must remember that longevity is even more desirable,
for it is the cows that stay in the herd until they are 10, 12
or 14 years of age that make the most profit."

SUMMARY AND CONCLUSIONS
Home-raised cows remained in 14 Florida dairy herds an
average of 4.7 years after attaining producing age, as com-
pared with 3.9 years for 101 herds in which replacements were
largely purchased. However, some animals in the latter herds
were purchased as milking cows.
Udder injuries and complications caused the largest single
source of loss among 2,182 cows from Florida herds. Low
production and reproductive troubles were the second and third
major causes of disposal. Deaths eliminated 14.2 percent of
total cows, attributed to Johne's disease, milk fever, mastitis
and udder complications, pneumonia and others. Accidents,
injuries from foreign bodies (wire, nails, etc.) and poisoning
from various causes accounted for many cows.
Of 2,254 bulls discarded while fertile, 34.5 percent were to
avoid inbreeding, 14.1 percent for bad disposition and 10.4 per-
cent for low production of daughters.
The natural services of 5,177 desirable bulls were terminated
by non-infectious and infectious causes. Over 25 percent be-
came sterile; causes of death of 11 percent were not reported;
accidents and injuries took 10 percent; inability to breed and
low fertility accounted for 8.8 percent; and advancing age took
nearly 8.8 percent.







Florida Agricultural Experiment Stations


Foreign bodies eliminated 5.3 percent of bulls in natural
service, contrasting with 3.04 percent in artificial units. Acti-
nomycosis caused removal of 3.69 percent of bulls in natural
and 2.70 percent in artificial use. Losses from all pathogenic
causes totaled 15.26 and 8.34 percent in natural and artificial
services, respectively. Good care of hoofs has helped to hold
losses from lameness and bad feet and legs to 3.88 percent in
artificial, as against losses of 5.08 percent in natural, service.
One hundred and ninety bulls in artificial use, born before
1937, averaged 2.72 years in service. Over 28 percent were
usable under 12 months, 55 percent for 1.0 to 4.9 years, while
6.0 percent were used artificially 7.0 to 10.75 years.
It is desirable to extend the profitable useful life of dairv cattle
by every reasonable means.

ACKNOWLEDGMENTS
The late Bruce McKinley, Associate Agricultural Economist, Florida\
Agricultural Experiment Station, helped initiate this project and assemble
earlier Florida records up to October 1940. Nine Florida dairymen joined
with four state institutions and a county home to supply continuous herd
records over a period of years. Breeders of Ayrshires, Brown Swiss,
Guernseys, Holstein-Friesians and Jerseys from the United States and
Canada contributed records of dairy bulls through direct correspondence.
The respective breed associations, their field representatives and the Ameri-
can Milking Shorthorn Association have cooperated extensively concerning
specific animals. The majority of artificial breeding units in America are
cooperating in studies involving their animals. Research of this nature
would have been impossible without such teamwork.




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