The changes in the milk composition and its lipid fraction during the rearing of lambs in non-milked sheep

The changes in the milk composition and its lipid fraction during the rearing of lambs in non-milked sheep. Studies regarding the effect of lactation stage on milk content and lipid fraction composition are mostly conducted on milked animals. The aim of this study was to analyze the changes in the basic milk composition and content of fatty acids in the fat fraction during the rearing of lambs in non-milked sheep. The study was carried out on 22 ewes of Polish lowland sheep of Żelazneńska strain, which reared lambs sold at low weight classes (up to 22 kg). Milk samples were collected at 10th (period 1), 25th (period 2) and 52nd (period 3) day of lactation. There were no differences in the amount of the basic components of milk in the studied periods of lactation beside the fat (P ≤0.05) content. There were also no difference in the content of fatty acid groups in the fat fraction of ewe’s milk examined at 10th, 25th and 52nd day of lactation. Although, in the third period of lactation, the content of saturated fatty acids (SFA) was slightly higher compared to first period. In turn, the content of oleic acid (P ≥0.30) and C18:3 (P ≤0.05) was higher in 10th day of rearing then in 52nd day. A slightly larger share of essential C18 unsaturated fatty acids in ewe’s milk in early lactation may suggest the involvement of adipose tissue in the formation of milk fat.