First estimates of lactation curves in White Shorthaired goats

Abstract

The objective of this study was to compare Cubic, Ali-Schaeffer, Guo-Swalve (modifi ed Khanderkar) and Wilmink models for fi tting lactation curves of White Shorthaired goats in Slovakia. In total, 19 002 test day records of daily milk yield, 18 441 test day records of fat content and 18 757 test day records of protein content of 1 486 does collected between 1996 and 2011, were analyzed. Milk traits were grouped by the week of lactation, and hence weekly averages of milk yield, fat and protein content were used for modelling the fi rst estimates of lactation curves. The goodness-of-fi t of the models was of similar quality (R2 slightly above 0.9 for milk yield, above 0.6 for fat content and above 0.7 for protein content); with the exception of Wilmink model which gave lower R2 for the three traits (0.842, 0.600, 0.426). Lack of data in early and late lactation caused some diffi culties in modelling the respective phases of lactation curves with chosen models. The greatest differences in lactation curves were found between Wilmink model and the remaining models. Research on individual days in milk is needed for better understanding of variation of milk traits during the course of lactation, since they may depend on such effects as number of kids, feeding, parity or individual doe.