The effect of nongenetic factors on milk yield and composition in goats of White Short-Haired breed
2000
Margetin, M. (Vyskumny Ustav Zivocisnej Vyroby, Nitra (Slovakia)) | Milerski, M.
The objective of the paper was to determine the effect of some nongenetic factors on milk yield and composition in goats of White Short-Haired breed (WSH); their population is largest in Slovakia. Another objective was to determine differences in the production and content of basic milk constituents in the goat population concerned using a suitable model of the analysis of covariance, in relation to lactation number and number of sucking kids. A total of 4,950 lactations of goats from 64 farms were assessed; data were acquired as part of milk records (MR) in 1995-1997. All records of WSH goats were excluded from the analysis if milking period (MP) was shorter than 150 days and longer than 325 days, if the interval between parturition and 1st milk control (INT) was shorter than 10 days and longer than 70 days, and if the actual milk yield of goats was lower than 100 l and higher than 1,300 l. Milk yield was measured after kid weaning. Other data excluded from the analysis concerned fat content lower than 2 % and higher than 5.5 %, average protein content lower than 2 % and higher than 4 % and average lactose content per milking period lower than 2 % and higher than 5 %. The least-squares method and several linear models with fixed effects were used for estimation of the effect of environmental factors in adjusted data from MR. All obtained data will be used to draw up proposals of new methods of breeding value estimates in WSH goats that should be used for selection aimed at faster genetic progress in milk and utilizable dry matter production.
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