Análisis de los efectos ambientales y genéticos que afectan a la producción de leche en vacas nodrizas de la raza Parda de Montaña

Abstract

The objective of this study was to analyse the environmental and genetic effects in monthly milk production of Parda de Montaña beef cows. Five hundred and eight lactations from 246 cows were studied. Milk production was obtained by machine milking following oxytocin stimulation. Milk production in each month of lactation (1 to 5) was treated as a different trait. The model included the animal effect (random), level of nutrition of the cow, calving season, sex of calf, calf supplementation and calf management. The animal genetic effect accounts from 19 to 40% depending on the month of lactation, and the genetic correlation between months was higher than 53%. The magnitude of the environmental effects changes between months. Autumn calving cows produced more milk in the first month of lactation whereas spring calving cows produced more in the 4th and 5th month of lactation. The level of energy in the cow ration affected the milk production from the second to the fifth month of lactation. The sex, supplementation and management of calf did not have consistent effects on milk production. Nevertheless the calf related factors have punctual effects that recommend the inclusion of these effects in future models.

Financiado por INIA (RTA 2010-57, RZP 2009-05 y RZP 2010-02).