Correlations between parities for lactation traits in United States dairy goats

Correlations between parities for milk yield, fat yield, and days in milk were calculated across and within does for five breeds of United States dairy goats; Alpine, LaMancha, Saanen, and Toggenburg, using lactation records to January 1981. Records were initiated during 1966 through 1979 and had between 125 and 305 d in milk. Parities were first through fourth, and fifth or greater. Overall phenotypic correlations between the three lactation traits averaged across breed were .95 between milk and fat yield and about .60 between milk or fat yield and days in milk. Within-herd phenotypic partial correlations between parities 1 and 2 (the two parities with most data) averaged .47 for milk yield, .42 for fat yield, and .07 for days in milk. Components of variance due to herd averaged about 34% for milk yield and for fat yield and 23% for days in milk. Components of variance due to doe/herd averaged 28% for milk yield, 25% for fat yield, and 17% for days in milk. Repeatabilities averaged .42 for milk yield, .38 for fat yield, and .22 for days in milk.