Resumo:
This study aimed to evaluate the effects of different concentrate levels and increased crude protein content in the diet on blood markers of hepatic and renal health in growing lambs. Two experiments were conducted with 64 intact male Santa Inês lambs, four months old, with an initial average weight of 20 ± 1 kg. The lambs were housed in individual pens and fed ad libitum during a 57-day experimental period, preceded by a 14-day adaptation period. The experimental design was a randomized complete block design (RCBD). Two experiments were conducted simultaneously to obtain the data used in this work. In Experiment 1 (Exp1), four diets with different concentrate levels (400, 500, 600, and 700 g/kg of DM) were tested. In Experiment 2 (Exp2), four diets with different crude protein levels (120, 140, 160, and 180 g CP/kg of DM) were evaluated.
Blood samples were collected on the 54th day in both experiments for analysis of serum albumin, urea, cholesterol, creatinine, alkaline phosphatase (AP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma- glutamyltransferase (GGT). The results indicated that the increase in concentrate level, expressed as digestible organic matter intake (dOM), did not significantly affect the blood parameters analyzed (P>0.05). However, serum urea levels were above the reference range (17 – 43 mg/dL) in Exp1, while creatinine levels were below the reference range (1.2 – 1.9 mg/dL). In Exp2, the increase in crude protein intake (CP) led to a significant linear increase in serum urea levels (P=0.0002), although no significant changes were observed for AP, albumin, AST, ALT, GGT, creatinine, and cholesterol (P>0.05). This study demonstrates that increasing the intake of DOM and CP beyond the requirements of confined lambs raises serum urea levels without affecting liver health, considering a 57-day experimental period.
