Tendencia genética y fenotípica de la producción de leche: caso de un establo comercial del valle de Huaura, Perú

The aim of this research was to determine the genetic and phenotypic trends for milk production (MP) of Holstein cows from a commercial herd in the Huaura Valley, Peru. A total of 2,590 females (cows and calves) were evaluated to calculate the estimated breeding values (EBV) and 2,862 standardized lactations at 305 days and two daily milkings, from the first to the fifth calving of 1,892 cows from 1999 to 2017, using a repeated-measures animal model. A heritability (h2) of 0.16 (standard error 0.03) and repeatability (r) of 0.28 (0.025) were estimated with the ASReml software. The trends were estimated by linear regression using the SAS statistical package v.9.4. The EBV for MP of the cows and calves had an average of +200.9 (16.1) kg and +148.7 (9.7) kg, respectively, with more than 70 % positive values among living animals. The genetic trend for female MP was -2.4 (2.1) kg/year. A phenotypic trend for MP of +294.3 (24.9) kg/year was estimated. It is concluded that the phenotypic trend is favorable due to improvements in non-genetic aspects, since h2 indicates that MP is mainly influenced by environmental variance and, to a lesser extent, by the additive genetic variance of the trait. The genetic trend for female MP was negative. However, the EBV for MP of living females suggests that in the future, the herd may increase the genetic trend for MP.