Discipline: Animal Science
Eight Holstein steers were grouped into two treatments, control and restricted-realimented (Rest-Real) steers, to understand the changes in plasma leptin, insulin-like growth factor-1 (IGF-1), insulin and metabolites during realimentation (REAL) period. The control steers were offered concentrate and silage diet, while the Rest-Real steers were given silage diet only for 145 days restriction period to obtain 25% lower body weight than control. The body weight and three-day feed intake were measured every two weeks. Blood sampling was performed at selected REAL period (days 0, 14, 29, 42, 56, 112 and 137). The aliquot plasma was analyzed for metabolites, insulin, IGF-1 and leptin. The control steers obtained significantly higher body weight, dry matter (DM) intake and DM to weight gain ratio but significantly lower average daily gain compared to Rest-Real steers. Plasma IGF-1 and plasma urea nitrogen (PUN) of Rest-Real steers were significantly lower than control steers from early to 56 days, elevated at 112 days and declined to control level at 137 days of REAL period. Plasma leptin appeared lower before 56 days and elevated at 137 days of REAL period indicating lower lipid deposition within 56 days REAL. Significantly lower PUN and plasma IGF-1 indicate lean deposition within 56 days of REAL period.