Influence of body condition and lasalocid during late gestation on blood metabolites, lamb birth weight and colostrum composition and production in Finn-cross ewes.

The objective of this experiment was to examine the effects of body condition (BC) and of lasalocid (L) the last 4 wk of gestation on blood metabolite profiles, lamb birth weight and colostrum composition and production. Twenty-eight 3-yr-old Finn-Targhee ewes (73 kg) were assigned randomly within BC grouping (2.5 or 3.5) and individually fed a diet of 90% alfalfa pellets and 10% of a supplement containing either no L (C = control) or L. Gestation and 24-h postlambing weights were higher (P less than .05) for 3.5 BC versus 2.5 BC ewes. Lasalocid had no effect (P greater than .05) on ewe weight. Average number of lambs born within treatment groups were similar (P greater than .05). Total kilograms of lamb born were greater (P less than .10) for 3.5 BC ewes. Body condition 3.5 ewes had greater concentrations of total protein (P less than .10) and albumin (P less than .05) the last 4 wk of gestation than those in the 2.5 BC group. Feeding L decreased (P less than .05) blood urea-N in comparison with C ewes. Colostrum composition and production were not influenced (P greater than .05) by BC, L or number of lambs born. Serum 3-hydroxybutyrate seemed to be a good indicator of energy metabolism; albumin and blood urea-N concentrations reflected dietary protein intake. Lasalocid had a minimal effect on nutrient metabolism and productivity of ewes fed in excess of the NRC (1985) protein and energy requirements.