Relationships between live weight and herd-test traits in a Saanen goat herd in New Zealand

Abstract

Genetic relationships among doe live weight and herd-test milk traits were investigated in a large herd of Saanen goats, managed with seasonal (spring) kidding and twice-daily milking. There were 34,183 herd-test records of milk solids yield (FPL) for 20 milking seasons to 2010–2011, with individual fat (F), protein (P) and lactose (L) yields in later seasons, somatic cell count (SCC) from 1999–2000 onwards (26,575 records), and weights recorded on four dates between June 2008 and November 2010 (4358 records). FPL, log10SCC and live weight were analysed using restricted maximum likelihood, with a repeated-animal model and full relationship matrix, yielding heritability estimates of 0.35±0.02, 0.20±0.02 and 0.64±0.04 respectively and repeatabilities of 0.48±0.01, 0.37±0.01 and 0.80±0.01 respectively. Genetic correlation estimates were 0.41±0.06 (FPL, live weight), −0.07±0.06 (FPL, log10SCC) and 0.24±0.08 (live weight, log10SCC). Expected correlated changes in doe live weight will depend on the selection index weights applied to doe weights and the other traits.