Journal of Animal and Veterinary Advances
ISSN: Online 1993-601XISSN: Print 1680-5593
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Abstract
Genetic parameters for birth weight BW and calving difficulty CD were evaluated in a herd , located in Samalayuca, a representative rangeland system in the desertic region at north of M?xico. Progeny (n=18 and n=19) from 41 dams: heifers and mature cows of a total of 50 dams involving inheritance of Limousin L mated naturally to sires L were used. The objective was to estimate heritability values direct for BW and CD. Separate analyses for each trait used least squares mixed model, SAS (1989). The analytical model included: year of birth, age of dam, sex of the calf, with date of birth as a covariate to adjust a common age as fixed effects; sire and residual as random components. Mean BW was 39.97 kg. BW ranged from 36.00 to 37.94 kg in heifers 29 month-old at parturition. BW ranged from 38.5 to 43.70 kg in mature cows that produced calves at 57 month-old. CD was subjectively evaluated categorically using descriptive scores (i.e., 1=no difficulty, 2= little difficulty by hand, 3 = little difficulty with jack, 4= slight difficulty with a calf jack, 5= moderate difficulty with calf jack, 6= major difficulty with jack and 7= Caesarean birth presentation). Calving difficulty was greater (P<0.05) in heifers (29.8%) than mature cows (11.45%). The sex of the calf was the major source (P<0.05) of variation in levels of CD for both heifers and mature cows. The estimates of heritability values for BW and CD difficulty were (h2=.29?.07) and (h2=.05 ?.04), respectively.
How to cite this article:
M?rquez, A. P. , J. F. Ponce , A. Correa , L. Avenda?o , M. Monta?o and J. Trejo . Estimates of Genetic and Phenotypic Parameters of Calf Birth
Weight and Calving Difficulty in Limousin Cattle.
DOI: https://doi.org/10.36478/javaa.2005.540.542
URL: https://www.makhillpublications.co/view-article/1680-5593/javaa.2005.540.542