Calculation of correction factors for daily milk production in dairy cattle in Costa Rica

Abstract

Correction factors for daily milk production were obtained using records of the racial groups Holstein (Hol\n = 112545), Jersey (JER\n = 36555), Guernsey (GUER\n = 4785), Brown Swiss (PSUI\n = 9975) and Bos Taurus-B crosses. Indicus (BTBI\n = 2940) and Bos Taurus-Bos Taurus (BTBT\15855). For HOL and JER additional factors were calculated within three life zones: humid forest (bh), very humid forest (bmh) and rain forest (bp). The variable of daily milk production was evaluated with a linear model that included the fixed effects of herd (H), calving year (APA), lactation length (ALL), lactation number (NL), calving season (EPA), day of lactation (Day) and the covariate days open (DA). Correction factors were generated for the variables NL, EPA and Dia. The variables of H, APA and ALL presented significant effects (P<.001) in all cases.