Early Feed Restriction Programs Metabolic Disorders in Fattening Merino Lambs

SIMPLE SUMMARY: Inadequate nutrition of lambs during early life may compromise their health status during their whole lifetime. The aim of this study was to investigate the long-term effects of milk restriction during the suckling period on biochemical, immunological, hepatic, and ruminal parameters of fattening lambs. The results obtained reveal that early feed restriction during the suckling period of merino lambs promotes systemic metabolic disorders during the fattening phase that are not related to ruminal acidosis occurrence. This information may contribute to design strategies to enhance the health status of lambs undergoing milk restriction due to low milk production (e.g., udder problems) or lack of lamb vitality. ABSTRACT: Early postnatal nutrition may have a significant subsequent impact on metabolic disorders during the entire lifespan of lambs. The aim of the present study was to describe the changes in biochemical, immunological, hepatic, and ruminal parameters of fattening lambs derived from early feed restriction during the suckling phase. Twenty-four merino lambs (average body weight, BW, 4.81 ± 0.256 kg) were used, 12 of them were milk-fed ad libitum (ADL) remaining permanently with their dams, whereas the other 12 lambs (restricted, RES) were subjected to milk restriction. After weaning, all the lambs were fed 35 g/kg BW per day of the same complete pelleted diet to ensure no differences between groups in dry matter intake (603 vs. 607 g/day for ADL and RES lambs, respectively, p = 0.703), and were slaughtered at a BW of 27 kg. Biochemical profiles revealed higher concentrations of ceruloplasmin and low-density lipoproteins, whereas insulin concentration was lower in the RES lambs compared to the ADL group. Liver thiobarbituric acid reactive substances were lower in the RES lambs. No significant differences in ruminal or blood immunological parameters were found. In conclusion, early feed restriction promoted metabolic disorders not related to ruminal acidosis occurrence, which can compromise the health status during the fattening period of merino lambs.