Event-time analysis of reproductive traits of dairy heifers
Data on the reproductive traits of dairy heifers were analyzed using event-time techniques. Traits analyzed were age at first calving (n = 4631), days to first breeding, and days open (n = 1992) during the first lactation. A proportional hazard model was used that included fixed effects of herd...
| Autores Principales: | VAN DER LENDE, T., Baaijen, Veerle M., VAN ARENDONK, J.A.M., Vargas, Bernardo |
|---|---|
| Formato: | Artículo |
| Idioma: | Inglés |
| Publicado: |
Elsevier
2022
|
| Materias: | |
| Acceso en línea: |
http://hdl.handle.net/11056/24077 |
| id |
RepoUNACR24077 |
|---|---|
| recordtype |
dspace |
| spelling |
RepoUNACR240772022-10-11T22:09:45Z Event-time analysis of reproductive traits of dairy heifers VAN DER LENDE, T. Baaijen, Veerle M. VAN ARENDONK, J.A.M. Vargas, Bernardo GANADO DE LECHE DAIRY CATTLE GESTACIÓN ANIMAL REPRODUCCION ANIMAL NOVILLOS DAIRY HEIFERS ANIMAL GESTATION ANIMAL REPRODUCTION Data on the reproductive traits of dairy heifers were analyzed using event-time techniques. Traits analyzed were age at first calving (n = 4631), days to first breeding, and days open (n = 1992) during the first lactation. A proportional hazard model was used that included fixed effects of herd-year, year-season, breed type, herd weight, and heifer weight. Body weights were recorded at 390 d of age, on average. The model for days open and days to first breeding included two additional fixed effects of herd and heifer milk yield at 100 d. A significant effect of heifer weight category on age at first calving was found. The chance of calving was consistently higher for herds and heifers with higher body weight at 390 d and decreased linearly from the top to the lowest quar- tiles. The effects of herd weight category on days to first breeding and days open were significant. Heifers in herds with a higher average body weight were less likely to be bred, and heifers in herds with lower average body weight were less likely to get pregnant. The effect of heifer weight category on days to first breeding or days open was not significant. The effect of herd milk yield on days to first breeding was sig- nificant. Heifers in herds with lower yield were more likely to be bred. The effect of heifer milk yield category on days to first breeding and days open was significant, but no linear trend was found for the estimates of the hazard ratios. The chance of a heifer being bred and becoming pregnant was similar among the first three quartiles and was lower for heifers in the lowest quartile. The probability of a heifer reach- ing a first calving can be improved by increasing the body weight at 390 d. Body weight at 390 d did not appear to have a large effect on reproductive perfor- mance after first calving. High milk yield appears not to have a large negative effect on days open, at least for the milk yield levels analyzed in this study. Los datos sobre los rasgos reproductivos de las novillas lecheras se analizaron mediante técnicas de tiempo-evento. Los rasgos edad al primer parto (n = 4631), los días hasta el primer primera cubrición, y los días abiertos (n = 1992) durante la primera lactancia. Se utilizó un modelo de riesgo proporcional que incluía efectos fijos de año de rebaño, año-estación tipo de raza, peso del rebaño y peso de la novilla. El peso corporal se registró a los 390 días de edad, en promedio. El modelo para los días abiertos y los días hasta la primera cubrición incluyó dos efectos fijos adicionales de rebaño y de leche de la novilla a los 100 días. de peso de las novillas sobre la edad del primer parto. La probabilidad de parir fue sistemáticamente mayor para los rebaños y novillas con mayor peso corporal a los 390 días y disminuía linealmente desde el cuarto más alto hasta el más bajo. Los efectos de la categoría de peso del rebaño sobre los días de la categoría de peso del rebaño sobre los días hasta la primera cubrición y los días abiertos fueron significativos. Las novillas de los rebaños con un peso corporal medio más alto eran menos propensas a ser criadas, y las novillas de los rebaños con peso corporal medio eran menos propensas a quedar preñadas. El efecto de la categoría de peso de las novillas sobre los días hasta la primera de cría o los días de apertura no fue significativo. El efecto de la producción de leche del rebaño sobre los días hasta la primera cubrición fue significante. Las novillas de los rebaños con menor rendimiento fueron más de ser criadas. El efecto de la categoría de rendimiento lechero de las novillas en los días hasta la primera cubrición y en los días abiertos fue significativo pero no se encontró ninguna tendencia lineal en las de los coeficientes de riesgo. La probabilidad de que una novilla se críe y quede preñada fue similar entre los tres primeros cuartiles y fue menor para las novillas en el cuartil más bajo. La probabilidad de que una novilla llegue al primer parto puede mejorarse aumentando el peso corporal a los 390 días. El peso corporal a los 390 días no de peso corporal a los 390 días no parece tener un gran efecto en la reproductiva después del primer parto. La alta producción de leche no parece tener un gran efecto negativo en los días abiertos, al menos para los niveles de producción de leche analizados en este estudio. Universidad Nacional, Costa Rica Escuela de Medicina Veterinaria 2022-10-11T22:00:53Z 2022-10-11T22:00:53Z 1998-11 http://purl.org/coar/resource_type/c_6501 http://hdl.handle.net/11056/24077 10.3168/jds.S0022-0302(98)75848-5 eng Acceso abierto http://creativecommons.org/licenses/by-nc-nd/4.0/ application/pdf Elsevier Journal of Dairy Science Vol. 81, INo. 11: 2881-2889, 1998 |
| institution |
Universidad Nacional de Costa Rica |
| collection |
Repositorio UNA-Costa Rica |
| language |
Inglés |
| topic |
GANADO DE LECHE DAIRY CATTLE GESTACIÓN ANIMAL REPRODUCCION ANIMAL NOVILLOS DAIRY HEIFERS ANIMAL GESTATION ANIMAL REPRODUCTION |
| spellingShingle |
GANADO DE LECHE DAIRY CATTLE GESTACIÓN ANIMAL REPRODUCCION ANIMAL NOVILLOS DAIRY HEIFERS ANIMAL GESTATION ANIMAL REPRODUCTION VAN DER LENDE, T. Baaijen, Veerle M. VAN ARENDONK, J.A.M. Vargas, Bernardo Event-time analysis of reproductive traits of dairy heifers |
| description |
Data on the reproductive traits of dairy heifers
were analyzed using event-time techniques. Traits
analyzed were age at first calving (n = 4631), days to
first breeding, and days open (n = 1992) during the
first lactation. A proportional hazard model was used
that included fixed effects of herd-year, year-season,
breed type, herd weight, and heifer weight. Body
weights were recorded at 390 d of age, on average.
The model for days open and days to first breeding
included two additional fixed effects of herd and
heifer milk yield at 100 d. A significant effect of heifer
weight category on age at first calving was found. The
chance of calving was consistently higher for herds
and heifers with higher body weight at 390 d and
decreased linearly from the top to the lowest quar-
tiles. The effects of herd weight category on days to
first breeding and days open were significant. Heifers
in herds with a higher average body weight were less
likely to be bred, and heifers in herds with lower
average body weight were less likely to get pregnant.
The effect of heifer weight category on days to first
breeding or days open was not significant. The effect
of herd milk yield on days to first breeding was sig-
nificant. Heifers in herds with lower yield were more
likely to be bred. The effect of heifer milk yield
category on days to first breeding and days open was
significant, but no linear trend was found for the
estimates of the hazard ratios. The chance of a heifer
being bred and becoming pregnant was similar among
the first three quartiles and was lower for heifers in
the lowest quartile. The probability of a heifer reach-
ing a first calving can be improved by increasing the
body weight at 390 d. Body weight at 390 d did not
appear to have a large effect on reproductive perfor-
mance after first calving. High milk yield appears not
to have a large negative effect on days open, at least
for the milk yield levels analyzed in this study. |
| format |
Artículo |
| author |
VAN DER LENDE, T. Baaijen, Veerle M. VAN ARENDONK, J.A.M. Vargas, Bernardo |
| author_sort |
VAN DER LENDE, T. |
| title |
Event-time analysis of reproductive traits of dairy heifers |
| title_short |
Event-time analysis of reproductive traits of dairy heifers |
| title_full |
Event-time analysis of reproductive traits of dairy heifers |
| title_fullStr |
Event-time analysis of reproductive traits of dairy heifers |
| title_full_unstemmed |
Event-time analysis of reproductive traits of dairy heifers |
| title_sort |
event-time analysis of reproductive traits of dairy heifers |
| publisher |
Elsevier |
| publishDate |
2022 |
| url |
http://hdl.handle.net/11056/24077 |
| _version_ |
1796095129233129472 |
| score |
12.043409 |