The effect of substitution of mixed grass hay with Urtica cannabina hay and/or Leymus chinensis hay on blood biochemical profile, carcass traits, and intramuscular fatty acid composition in finishing lambs

In this study, the effects of substitution of mixed grass hay with Urtica cannabina hay and/or Leymus chinensis hay on blood metabolites, carcass traits, and intramuscular fatty acid composition of finishing lambs were assessed. Thirty-two male Ujumuqin × small-tailed Han lambs were randomly allocated into four dietary treatment groups (n = 8): (1) 500 g/kg mixed grass hay + 500 g/kg concentrate (control, G50); (2) 500 g/kg Leymus chinensis hay + 500 g/kg concentrate (L50); (3) 500 g/kg flowering U. cannabina hay + 500 g/kg concentrate (U50); and (4) 250 g/kg L. chinensis hay + 250 g/kg flowering U. cannabina hay + 500 g/kg concentrate (L25-U25). Diets were provided in a pellet form and animals were individually fed during the 57-day experimental period. All lambs were slaughtered after the feeding trial. Compared to the control diet, the U50 and L25-U25 diets increased (P = 0.001) glucose concentration and decreased total cholesterol and triglyceride concentrations in lamb’s blood (P = 0.022 and 0.015, respectively). The U50 and L25-U25 groups had greater (P = 0.001) total antioxidant capacity and lower (P = 0.019) malondialdehyde value; and the U50 group had greater (P = 0.003) catalase activity, compared to the control group. Carcass traits were unaffected by dietary treatment, but meat of the U50 and L25-U25 lambs contained lower levels of saturated and monounsaturated fatty acids (P = 0.031 and 0.048, respectively), and greater (P