Factores que afectan la edad al primer parto y la producción de la primera lactancia, en vacas de hatos lecheros especializados de Costa Rica, durante los años 2013 al 2015
Archivos
Fecha
2018
Autores
Castillo Badilla, Gloriana
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Editor
Universidad Nacional, Costa Rica
Resumen
Se determina el efecto de los factores de animal y ambiente, sobre la edad al primer
parto (EPP) y la producción de la primera lactancia (PPL), en vacas de hatos lecheros
especializados de Costa Rica, durante el período comprendido entre los años 2013 al 2015.
El primer estudio consiste en una cohorte retrospectivo para cuantificar el efecto de
variables de animal y ambiente, modificables y no modificables, sobre la edad al primer
parto. Se incluye 2.980 animales de razas Jersey y Holstein que presentan su primer parto
entre los años 2013 y 2015; pertenecientes a 22 hatos lecheros especializados, ubicados en
diferentes zonas ecológicas de Costa Rica, con datos en el programa VAMPP Bovino. Se
analiza los datos mediante estadística descriptiva y un modelo lineal generalizado para la
variable dependiente. La EPP promedio, para los animales en estudio, es 27.4 meses (±
4.7). Variables no modificables del individuo, como la raza, presentan efectos significativos
en la EPP, con valores de 30.1 (IC95%: 29.8-30.4) y 28.4 meses (IC95%: 28.1-28.8;
P<0.001) en la raza Holstein y Jersey, respectivamente. Por otra parte, se determina un
efecto significativo de la variable modificable de manejo (P<0.0001), en la cual, las fincas
con protocolos de alta calidad de crianza de terneras presentaron EPP de 27.6 meses
(IC95%: 27.2-28.0), a diferencia de las fincas con bajo desarrollo de reemplazos (EPP:
30.2; IC95%: 29.8-30.6). Esta tendencia se mantuvo, tanto en el análisis de la variable de
manejo de forma independiente, como en asociación con raza y finca, en donde la
eficiencia de las técnicas de crianza se refleja en mejores valores de EPP.
El segundo estudio, también, corresponde a una cohorte retrospectivo. Se utiliza
2.747 animales, con las mismas características del caso anterior. La PPL promedio, a 305
días, para los animales en estudio, es 5485.8 kg (± 1547.8). Variables no modificables del
individuo, como la raza, presenta efectos significativos sobre la PPL, con valores de 5360.1
kg (IC95%: 5158.2-5562.1) y 4694.1 kg (IC95%: 4578.5-4809.7) en la raza Holstein y
Jersey, respectivamente. Asimismo, se observa una tendencia a incrementar los niveles de
producción conforme se aumenta la edad al primer parto hasta los 26 meses (P<0.001),
después de lo cual se mantiene estable. Por otra parte, se determina un efecto significativo
de la variable modificable de manejo (P<0.0001); fincas con protocolos de alta calidad de
crianza de terneras produjeron 213.9 kg (PPL: 5809.0; IC95%: 5570.6-6047.4) más de
leche, en su primera lactancia, que las novillas con una crianza media y 1133.7 kg más que
las de sistemas de baja calidad de manejo (PPL: 4676.3; IC95%: 4158.3-5194.3). Estos
resultados evidencian la influencia que tienen las estrategias de crianza de terneras sobre el
rendimiento productivo posterior del animal en sistemas tropicales, principalmente la
variable de manejo sanitario, la cual, presenta mayor peso sobre los parámetros
reproductivos de una novilla.
The objective of this work was to quantify the effect of animal and environmental factors on age at first calving (AFC) and first lactation milk yield (FLM), of cows belonging to specialized dairy herds from Costa Rica., during the 2013-2014 periods. The first chapter consisted in a cohort retrospective study was carried out to quantify the effect of the animal and environmental factors, modifiable and non-modifiable, on age at first calving. A total of 2980 Jersey and Holstein cows with AFC in the period between 2013 and 2015 were included in the study, belonging to 22 specialized dairy herds located in different ecological zones of Costa Rica, with data in the Bovine VAMPP program. All data in the present research, was analyzed by descriptive analysis and a generalized linear model. The average AFC for the animals in the present study was 27.4 months (± 4.7). Non modifiable variables, like breed, had significant effect over AFC, with 30.1 (CI95%: 29.8-30.4) and 28.4 months (CI 95%: 28.1-28.8) for Holstein and Jersey respectively. Furthermore, the results showed a significant effect of management as a modifiable variable (P<0.0001) revealing that farms with high quality calf rearing protocols had AFC of 27.6 months (CI95%: 27.2-28.0), contrary to low quality systems (AFC: 30.2; CI95%: 29.8-30.6). This tendency was consistent whether the management variable was included as independent in the model or associated to breed and herd factors, where high efficiency in calf rearing reflects into better values of AFC. The second chapter also corresponded to a cohort retrospective study, using 2747 cows of the same characteristics of the first chapter. The average FLM at 305 days for the animals in the present study was 5485.8 kg (±1547.8). Non modifiable variables, like breed, had significant effect over FLM, with 5360.1 kg (CI95%: 5158.2-5562.1) and 4694.1 (CI95%: 4578.5-4809.7; P<0.001) for Holstein and Jersey respectively. AFC had a significant effect over FLM, were a tendency to increased milk production with higher AFC was found until 26mo of AFC, after that milk yield remain stable (P<0.001). Furthermore, the results showed a significant effect of management as a modifiable variable (P<0.0001) revealing that farms with high quality calf rearing protocols produced 213.9 kg (FML: 5809.0; CI95%: 5570.6-6047.7) more milk in their first lactation than heifers raised under medium quality rearing and 1133.7 kg more milk than animals from low quality rearing programs (FML: 4676.3; CI95%: 4158.3-5194.3). These results show that rearing factors affect the productive life time of dairy cows under tropical conditions.
The objective of this work was to quantify the effect of animal and environmental factors on age at first calving (AFC) and first lactation milk yield (FLM), of cows belonging to specialized dairy herds from Costa Rica., during the 2013-2014 periods. The first chapter consisted in a cohort retrospective study was carried out to quantify the effect of the animal and environmental factors, modifiable and non-modifiable, on age at first calving. A total of 2980 Jersey and Holstein cows with AFC in the period between 2013 and 2015 were included in the study, belonging to 22 specialized dairy herds located in different ecological zones of Costa Rica, with data in the Bovine VAMPP program. All data in the present research, was analyzed by descriptive analysis and a generalized linear model. The average AFC for the animals in the present study was 27.4 months (± 4.7). Non modifiable variables, like breed, had significant effect over AFC, with 30.1 (CI95%: 29.8-30.4) and 28.4 months (CI 95%: 28.1-28.8) for Holstein and Jersey respectively. Furthermore, the results showed a significant effect of management as a modifiable variable (P<0.0001) revealing that farms with high quality calf rearing protocols had AFC of 27.6 months (CI95%: 27.2-28.0), contrary to low quality systems (AFC: 30.2; CI95%: 29.8-30.6). This tendency was consistent whether the management variable was included as independent in the model or associated to breed and herd factors, where high efficiency in calf rearing reflects into better values of AFC. The second chapter also corresponded to a cohort retrospective study, using 2747 cows of the same characteristics of the first chapter. The average FLM at 305 days for the animals in the present study was 5485.8 kg (±1547.8). Non modifiable variables, like breed, had significant effect over FLM, with 5360.1 kg (CI95%: 5158.2-5562.1) and 4694.1 (CI95%: 4578.5-4809.7; P<0.001) for Holstein and Jersey respectively. AFC had a significant effect over FLM, were a tendency to increased milk production with higher AFC was found until 26mo of AFC, after that milk yield remain stable (P<0.001). Furthermore, the results showed a significant effect of management as a modifiable variable (P<0.0001) revealing that farms with high quality calf rearing protocols produced 213.9 kg (FML: 5809.0; CI95%: 5570.6-6047.7) more milk in their first lactation than heifers raised under medium quality rearing and 1133.7 kg more milk than animals from low quality rearing programs (FML: 4676.3; CI95%: 4158.3-5194.3). These results show that rearing factors affect the productive life time of dairy cows under tropical conditions.
Descripción
Palabras clave
REPRODUCCIÓN ANIMAL, COSTA RICA, JERSEY, GANADO DE LECHE, VACAS, ANIMAL REPRODUCTION, MILK CATTLE, COWS