Factors affecting standardized milk and fat yields in Alpine goats

Abstract

Records from 499 lactations of 220 Alpine does were evaluated to test lactation year, lactation number, and litter size effects on 305-day adjusted mature equivalent milk and fat yields. Milk yield was greater ( P < 0.01) in 1986 (968 kg) than in following years (range 777–845 kg). Fat yield was not influenced by lactation year. Positive ( P < 0.01) associations were found when phenotypic merits for lactation yield were regressed on birth year and generation. Lactation number affected ( P < 0.01) milk yields with production highest at second lactation (960 kg) and lowest at seventh lactation (634 kg). Does delivering single kids had lower ( P < 0.01) milk yields (775 kg) than does delivering twins and triplets (834 and 903 kg, respectively). A positive ( P < 0.01) coefficient was computed (17.5 ± 4.5 kg milk kg −1 litter weight) when milk yield was regressed on total litter weight. Fat yield was similarly affected ( P < 0.01) by lactation number and litter characteristics. Unique were results showing that litter size and litter weight had positive relationships with lactation yields in does despite the removal of kids at birth.