EN
The aim of the study was to determine the effect of lactation on blood biochemical components and body weight in Kamieniec ewes nursing singles or twins. The examinations were conducted on 4-year-old ewes; 12 suckling single lambs and 12 suckling twin lambs. The feeding level was maintained constant during a 70-d lactation period. The course and consequences of lactation in ewes nursing singles and twins were compared taking into account daily milk yield, milk production over lactation, milk chemical composition, and blood biochemical indices. Milk yield was found to be significantly (by more than 20%) higher in ewes nursing twins, reaching 27.40% towards the end of lactation. Milk production over lactation was higher in the mothers of twins, by 23.67 kg (P≤0.05). No significant differences were observed between ewes suckling singles and twins with respect to the chemical composition of milk. Changes in blood biochemical indices, primarily in the activity of ALT and AST, concentrations of protein, urea, and creatinine, as well as in the parameters of acid-base balance indicate that lactation has a greater challenge in the ewes nursing twins.