| Material Information
||The influence of lactation status within age on reproductive performance of Brahman cows /
||Mimeo report ;
||3 leaves : ; 28 cm.
||Peacock, F. M ( Fentress McCoughan ), 1922-
Agricultural Research Center, Ona
||Agricultural Research Center,
Agricultural Research Center
||Place of Publication:
||Beef cattle -- Breeding -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )
||Statement of Responsibility:
||F.M. Peacock ... et al..
| Record Information
||University of Florida
||University of Florida
||All rights reserved by the source institution and holding location.
||oclc - 85894505
Agricultural Research Center, Ona -
d Mimeo Report RC-1972-12 July, 1972
THE INFLUENCE OF LACTATION STATUS
WITHIN AGE ON REPRODUCTIVE PERFORM ME LIBRARY
OF BRAHMAN COWS JUL 2 )1972
F. M. Peacock, W. G. Kirk,
M. Koger and A. C. Warnick .FAS. Univ. Of Florida
The importance of reproduction in beef cattle cannot
be over-emphasized. The percentage of calves-weaned or
sold determines to a great extent the economic success of
a cow-calf operation.
Low weaning percentages in the South (Temple 1965)J
at 67.5% and in Florida 71.3% make it necessary to study
the reproductive behavior of the various beef breeds.
In an attempt to characterize the Brahman breed for
reproduction rate, records for a 24 year period have been
studied at the Ona Agricultural Research Center as to the
effect of age and lactation status within age on reproductive
l/ Associate Animal Husbandman, Animal Scientist, Emeritus,
Agricultural Research Center, Ona. Animal Geneticist,
Animal Physiologist, Animal Science Department, Gainesville.
g/ Temple, R. S. 1965. Reproduction of Beef Cattle in
the South. Presented at Florida Beef Cattle Short
Course, University of Florida. Gainesville, May 6-7, 1965.
The data represented 1038 observations and included
cows ranging in age from females first bred as two year olds
to cows bred at 17 years of age. Data on the influence of
lactation status within age on calving, weaning and death
loss of calves expressed by percentage are presented in Table 1.
Average percentage for cows of all ages was 74.3 for
calving, 71.5 for weaning and 3.8 for death loss of calves.
Non-lactating 2 year olds calved at 65.4%, increased to
85.7% for the non-lactating three and four year olds. The
5 year olds calved at 91.7%, highest for the non-lactating
cows. Non-lactating cows from 6 through 17 years maintained
a relatively high calving rate. This indicates slow sexual
maturity for two year olds but by 3 years of age sexual
maturity for this population had been attained.
Lactation exerted the greatest influence on reproduc-
tion. Lactating three year old females had a 49.5% calving
rate, increasing to 68.2% at 4 years and a further increase
to 81.6% at 5 years of age. Lactating cows 6 to 12 years
of age maintained a high calving rate of 78.7%, but from
13 to 17 years of age calving dropped to 68%. These data
indicate the lack of physiological maturity until approx-
imately 5 years of age and a decline in physiological
state at 13 years of age under the prevailing management
Death loss of calves was lowest in 5 to 17 year old
cows. Non-lactating cows had a higher average death loss
than lactating cows but most of the difference could be
attributed to the high death loss for the non-lactating
three year old females. The higher death loss for the
young cows indicates a possible association between the
physiological age of the cow and the prenatal environment
of the calf. Physiological immaturity of these females
could have affected size and nutrition of the fetus as
well as difficulties at partuition.
Data have been presented on 1038 observations for
reproductive performance of Brahman females being bred at
2 through 17 years of age relative to lactation status
within age. The data indicates that two year old females
lacked sexual maturity for a high percentage calf crop
but at three years of age sexual maturity for the population
had been attained. From 3 through 17 years of age average
calving rate was over 85% for the non-lactating cow. Cows
suckling calves increased in calving percentage to 5 years
of age indicating a lack of physiological maturity until
approximately 5 years old. A relatively high reproductive
level was maintained through 12 years of age,then dropped
due to stress from lactation.
TABLE 1. INFLUENCE OF LACTATION STATUS WITHIN AGE OF DAM ON REPRODUCTIVE PERFORMANCE
OF BRAHMAN COWS.
Age of Dam Lactation Number in Birth Rate Wean Rate Death Rate
when Bred status Breeding herd % % %
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