Agricultural Economics Series 52-9
TURNOVER OF COWS IN FLORIDA DAIRY HERDS
A. H. Spurlook
NOV 24i '7x
Florida Agricultural Experiment Station, Gainesville, Florida
The lifespan of dairy cows is of concern to every dairyman, since the
number of years in the herd is oAe factor in determining their annual cost
or depreciation, Records have been obtained from about 14 herds in the
state on the useful lifespan and reasons for death or disposal of dairy cows.
Some of these data are from institutional herds such as those at the Uni-
versity of Florida and the Florida State University, and some are from com-
All the herds included raised most of their replacements. The percent-
age of purebred cattle in these herds is also higher perhaps than the aver-
age for all commercial dairies. The effect of these qualifications on life-
span of the animals is not known. It is believed that a purebred animal
will be culled for low production, undesirable type, or communicable disease
as quickly as any. There may be circumstances, however, in which a cow with
a high-production history that develops some defect may be kept for her off-
spring longer than a grade cow would.
On October 1, 1952 individual records were available on the lifespan of
1,742 cows which had reached the age of two years or more and come into the
milking herd. Animals which died or were sold as heifers were not included,
as were those milking cows sold for breeding or dairy purposes before their
useful life was over. The average age of all the 1,742 cows, with the num-
ber going out of the herd each year is given in Table 1.
Table l.--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.)
i Number of s: Average : Anticipated
Attained Age : Cows i Percent of s Age at :Usefulness at
:Still LivingsTotal Numbert Disposal tDifferent Ages
(Years) : (Number) a (Percent) : (Years) a (Years)
2.0 2,9 i 1,742 a 100.0 : 6.7 S 4.2
3.0 3.9 s 1,635 s 93.9 s 7.0 s 3.5
4.0 4.9 1,416 % 81.3 s 7.5 : 3.0
5,0 5.9 : 1,180 : 67.7 : 8.2 s 2.7
6.0 6.9 t 932 t 53.5 : 8.9 : 2.4
7.0 7.9 s 740 s 42.5 t 9.5 r 2,0
8.0 8.9 s 554 s 31.8 t 10.2 1.7
9.0 9.9 s 370 t 21.2 s 11.1 1.6
10.0 10.9 s 253 a 14.5 ; 11.9 : 1,4
11,0 11.9 : 162 : 9,3 : 12.8 : 1.3
12.0 12.9 s 103 : 5.9 s 13.5 1.0
13.0 13.9 t 58 t 3.3 s 14.4 : .9
14.0 14.9* s 29 s 1.7 s 15,5 a 1.0
15.0 15.9* s 18 1.0 s 16.3 : .8
16.0 16.9* 10 : .6 t 17.0 : .5
i7.0 17.9* s : :
18.0 18.9* 3 t .2 a 18.4 .0
19.0 19.9* 1 .1 a 19.2 : .0
Insufficient numbers to be reliable.
All the cows averaged 6.7 years of life or about 4.7 years of useful-
ness in the milking herd, assuming that they came in at about 2 years. At
6.0 years of age only 67.7 percent of the original number of cows remained
in the herd and at 10.0 years 78.8 percent were gone (21.2 percent remain-
ed). A few cows lived to very old ages. Almost 6 percent of the original
number reached 13.0 years of age, and one animal lived to be over 19.
A dairyman buying a sound cow between 4.0 and 4.9 years of age may ex-
pect on the average about 3.0 years additional from her; an animal between
8.0 and 8.9 years old can be expected to last about 1.7 years longer. From
Table 1 additional life expectancy can be obtained for any cow from 2 to 13.9
years of age. Above this age, the number of observations in each age group
is too small to be reliable.
In 1949, date were obtained from 101 commercial dairies in ix areas of
the State concerning the rate of turnover of cows in the herd../_ By using
the rate of turnover for one year in these dairies, years of life in the herd
were calculated as shown in Table 2. However, the age of these cows at en-
trance into the herd was not known.
Table 2.--Average Life in Herd of Cows in 101 Commercial Dairies of Six
Areas of Florida, 1949.
Average Life in
Area Herd (Years)
St. Petersburg 2.6
Palm Beach 4.9
Simple Average 4.0
About one-third of the replacements in the Orlando area were raised,
and 20 percent in the Palm Beach area. Only a relatively few replacements
were raised in the other areas, but the proportion is now increasing.
In the same study it w as found that cows lasted somewhat longer in
small herds than in large herds, the averages being 4.6 and 3.7 years re-
In Table 3 are given the principal reasons for disposal of 2,182 dairy
cows as obtained from the individual lifespan records. The number of animals
is greater than the total in Table 1, because for some cows the reason for
disposal was known although the birthdate may not have been available. Rea-
sons for disposal are those given by the dairy owner, herdsman, or someone
familiar with the cows. In the case of death or disposal for disease the
diagnosis was often made by a Veterinarian.
The leading cause of disposal of cows while living was mastitis or udder
trouble which accounted for 21.3 percent of all cows replaced. Almost as
I/Cost of Producing Milk in Selected Areas of Florida, Agricultural Economics
Series No. 51-4, January 1951. Florida Agricultural Experiment Station.
Table 3.--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 I Number of Cows I Percent of Total
Mastitis and udder trouble s 464 : 21*3
Low production a 410 : 18,8
Reproductive troubles a 276 s 12.7
Combinations of above 114 i 5.2
Diseases s 85 S 3.9
Old Age a 70 s 3.2
Accidents and injuries s 49 t 2.2
Other Reasons a 38 : 1.7
Unstated 367 : 16.8
Diseases a s
Johnne's 22 i
Milk Fever s 20 s
Mastitis and udder a 19 ;
Anaplasmosis a 16 s
Acetonemia s 12
Other diseases : 33
Total diseases 122 s
Reproductive troubles a 44 $
Accidental death, poisoning 39 :
Old Age : 14 s
Other Causes s 47 s
Unknown causes : 43 :
Total deaths a 309 : 14.2
Total 2182 s 100.0
Sources From unpublished data of the Florida Agricultural Experiment Station.
many cows were removed from the herd for low production, being 18.8 percent.
Reproductive troubles caused the elimination of 12,7 percent of the cows;
old age 3.2 percent; accident and injuries 2.2 percent and diseases 3.9 per-
cent. Various combinations of the above reasons caused replacement of 5,2
percent. Reasons were unknown for 16.8 percent of the disposals.
Death caused the loss of 14.2 percent of the cows. Of the deaths al-
most 40 percent were caused by various diseases, the leading of which were
Johnne's disease, milk fever, mastitis and udder complications, anaplasmosis
and acetonemia. A few deaths were caused by pneumonia. Reproductive trou-
bles caused 14 percent of the deaths; accidents and poisoning caused 12.6
percent. The accidents were caused by falls, electrocution and swallowing
foreign bodies such as baling wire. Poisoning was caused by eating poisonous
plants, from licking paint buckets, or fertilizer materials.
Recent high prices of beef animals have helped to keep the loss from
replaced dairy cows low, and may affect the rate of turnover also. However,
the price of a cow for beef will not pay the cost of raising or buying a
suitable replacement. It is desirable to extend the useful life of a good
dairy cow by every reasonable means at the disposal of the dairyman.
AHS:mm 10/13/52; Exp. Sta., Ag.Ec. 250