The effect of grazing intensity and supplementation on performance, stress indicators and metabolic profiles of finishing lambs

Abstract

In the present study, the effect of grazing intensity (GI) and feed supplementation in sixty-four crossbred Santa Inês lambs was assessed based on performance, blood stress indicators, and metabolic profiles. The GIs analyzed were VH = very high, H = high, L = low, and VL = very low, and were represented by the residual leaf area index (LAIr). The lambs were divided into two groups, supplemented (SP) and non-supplemented (NSP). The dry matter intake (DMI) and average daily gain (ADG) increased linearly with decreasing GI (P < 0.05), and the ADG was higher for the NSP group than the SP group (P < 0.05). The plasma cortisol concentration was higher in the NSP group (P < 0.05), and it was not affected by GIs (P > 0.05). The neutrophil:lymphocyte (N:L) ratio decreased linearly with GI (P < 0.05), and the SP group had a higher N:L ratio (P < 0.05). None of the parameters evaluated for protein metabolism were affected by GI (P > 0.05), except albumin, where the SP group had a higher concentration of this metabolite (P < 0.05). Regarding energy metabolism indicators, glucose showed a linear increase with a decrease in GI (P < 0.05) and was higher in the SP group (P < 0.05); however, there was a decreasing linear effect (P < 0.05) and the NSP group had higher serum levels (P < 0.05) of non-esterified fatty acids (NEFA). The concentration of beta hydroxybutyrate (HBA-B) was higher in the SP group (P < 0.05). The concentration of calcium was affected by GI (P < 0.05). The phosphorus concentration was higher in the SP group (P < 0.05), and concentration of magnesium was not affected by any of the treatments (P > 0.05). It was concluded that GI and SP modified the performance, stress indicators, and metabolic profiles of finishing lambs.