Factors affecting ewe's milk fat and protein content and relationships between milk yield and milk components
2007
Oravcova, M.,Vyskumny Ustav Zivocisnej Vyroby, Nitra (Slovak Republic) | Margetin, M.,Vyskumny Ustav Zivocisnej Vyroby, Nitra (Slovak Republic) | Peskovicova, D.,Vyskumny Ustav Zivocisnej Vyroby, Nitra (Slovak Republic) | Dano, J.,Vyskumny Ustav Zivocisnej Vyroby, Nitra (Slovak Republic) | Milerski, M.,Vyzkumny Ustav Zivocisne Vyroby, Prague (Czech Republic) | Hetenyi, L.,Vyskumny Ustav Zivocisnej Vyroby, Nitra (Slovak Republic) | Polak, P.,Vyskumny Ustav Zivocisnej Vyroby, Nitra (Slovak Republic)
Test-day records of purebred Tsigai, Improved Valachian and Lacaune ewes were used to analyse the effect of environmental factors on milk fat and protein content. There were 121,424 and 121,158 measurements of fat and protein concentrations for Tsigai, 247,742 and 247,606 for Improved Valachian, resp., and 2,194 measurements for both protein and fat concentrations for Lacaune ewes lambing between 1995 and 2005. Overall means and standard deviations for fat and protein concentrations were 7.77+/- 1.606% and 5.94+/-0.690% for Tsigai, 7.48+/-1.446% and 5.82+/-0.620% for Improved Valachian, 6.97+/-1.514% and 5.62+/-0.692% for Lacaune. For fat content, analyses showed a highly significant effect of flock-test day and a highly significant or significant effect of the month of lambing, with the only exception of the month of lambing in Lacaune. The effect of litter size was also significant in both Improved Valachian and Lacaune. For protein content, analyses showed a highly significant effect of flock-test day and a significant effect of the month of lambing. The effect of litter size was highly significant in Tsigai and Improved Valachian. Covariates of days in milk which modelled the shape of lactation curves were insignificant, except for Improved Valachian fat concentration (Ali-Schaeffer regression adopted for sheep). The model explained about 50% of fat and protein variation in the breeds. Fat and protein concentrations were almost equally correlated with milk yield. The model served to construct Lactation curves.
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