Factors influencing length of productive life and replacement rates in the Bruna dels Pirineus beef breed

被引:10
作者
Tarrés, J
Puig, P
Ducrocq, V
Piedrafita, J [1 ]
机构
[1] Univ Autonoma Barcelona, Dept Ciencia Anim & Aliments, Grp Recerca Remugants, E-08193 Barcelona, Spain
[2] Univ Autonoma Barcelona, Dept Matemat, Serv Estadist, E-08193 Barcelona, Spain
[3] INRA, Genet Quantitat & Appl Stn, F-78352 Jouy En Josas, France
来源
ANIMAL SCIENCE | 2004年 / 78卷
关键词
beef cattle; productive life; replacement; survival;
D O I
10.1017/S1357729800053790
中图分类号
S8 [畜牧、 动物医学、狩猎、蚕、蜂];
学科分类号
0905 ;
摘要
An analysis of the length of productive life in the Bruna dels Pirineus beef breed was performed with a nonparametric approach giving an average value of 9 years of productive life, and a corresponding replacement rate of 11%. Using a proportional hazards model stratified by herd, the influence of calf birth weight and weight gain until weaning, calving difficulty, calving interval and age at first calving on length of productive life were studied. Two models were explored : the first one included time-dependent variables taking the current value of the covariate at each calving date, while the second one also comprised time-dependent interactions between the value of the covariate of the current calving and its mean value during the last ( up to) three previous calvings. Results from the first model showed that the risk of culling increases with very high ages at first calving, increasing calving difficulties, very large calf birth weights, very small weight gains until weaning and very long calving intervals. Furthermore, results from the second model showed that these increases also depend upon a sequence of values for the same covariate in previous calvings. Finally, these higher risks of culling implied lower survival functions that increased replacement rates but only slightly decreased average performances.
引用
收藏
页码:13 / 22
页数:10
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