Effects of supplementation on performance and blood biochemical index of grazing reserve ewes in the cold season

This study aimed to determine a suitable formula for a supplement for grazing reserve ewes. Forty 8-month-old Altay reserve ewes, of similar weight, were divided randomly into 4 equal group. Three supplement groups were fed 350 g·d⁻¹ concentrate, with the ratios of RDN to FOM being 35, 30, and 25, respectively, in an adequate diet of R:F₃₅, R:F₃₀, and R:F₂₅; the control group (CON) was not fed. The experiment lasted for 45 days. The results were as follows. 1) At the end of the experiment, the body weights of animals in groups R:F₃₅, R:F₃₀, and R:F₂₅ were 20.48%, 19.24%, and 17.90% higher, respectively, than those in the CON group (P < 0.01); average daily gain of 3 groups fed the supplement was higher than the CON group (P < 0.01). 2) The serum GLU content of groups R:F₃₅ and R:F₃₀ was significantly higher (P < 0.01) than that of the CON group. 3) The serum UN content of groups R:F₃₅ and R:F₃₀ was significantly higher (P < 0.05) than of the CON group, the serum AST content of group R:F₃₅ was significantly higher than that of the CON group (P < 0.05), and the serum ALT content of group R:F₂₅ was significantly lower (P < 0.05) than that of the CON group. 4) The serum TG content of group R:F₃₅ was significantly higher than that of the CON group (P < 0.05), while the serum ALP content of groups R:F₃₅ and R:F₃₀ was significantly higher than that of the CON group (P < 0.01). 5) The serum K⁺, Na⁺, Cl⁻, Ca²⁺, and Mg²⁺ ions levels did not change (P > 0.05), and the serum IP content of group R:F₂₅ increased (P < 0.05) by 23.24% relative to the CON group. In conclusion, the loss in grazing reserve ewe body weight could be reduced when they were supplied concentrates in a timely manner. Under the conditions of the present study, the levels of energy, protein, and fat metabolism improved, and an adequate diet with different ratios of RDN to FOM had no impact on the level of any serum mineral element except IP. The optimum ratio of RDN to FOM of the adequate diet is 35.