Metabolic profiles and follicular dynamics of prepubertal and pubertal Santa Inês ewe lambs with dietary restriction and supplementation with roasted whole soybeans

Abstract

The objectives of this study were to evaluate moderate feed restriction and lipid supplementation on follicular dynamics, serum concentrations of fatty acids, and metabolic profile of prepubertal and pubertal ewe lambs. Thirty-five Santa Inês ewe lambs were randomly assigned according to body weight in an unbalanced block design with a 2 × 2 factorial arrangement, which consisted of level of intake (ad libitum - AL or restricted - FR), lipid supplementation (with or without whole roasted soybean). Ewe lambs in the FR group had 85% of the diet offered to those in the AL group. Ovulation was retrospectively defined by serum progesterone sample ≥ 1 ng/mL. The physiological status, ovulating (OV) and not ovulating (NOV), was considered as a two-level covariate. Dry matter and ether extract intake were greater in unsupplemented than supplemented AL ewe lambs that had ovulated (intake level x lipid supplementation x physiological status, P < 0.05). Plasma glucose and serum triglyceride concentrations were higher (P < 0.05) in supplemented animals, but no changes were observed in serum insulin concentrations (P > 0.05). In the unsupplemented animals, serum high-density lipoprotein (HDL) and cholesterol concentrations were higher in FR animals than in AL animals; serum HDL and cholesterol concentrations did not differ between lipid-supplemented groups (intake level x lipid supplementation, P < 0.05). Serum HDL was higher (P < 0.05) in animals that had ovulated than in animals that had not ovulated. In supplemented ewe lambs, serum stearic concentrations were greater in the AL group than in the FR group; conversely, in unsupplemented animals, stearic concentrations were lower in the AL group than in the FR group (intake level x lipid supplementation, P < 0.05). The linoleic serum concentrations were not affected (P > 0.05) by intake level, lipid supplementation, or physiological status. The number of follicular waves was greater (P < 0.05) in AL ewe lambs than in FR ewe lambs. There was no main effect of treatment or interaction effects (P > 0.05) on the number of follicles, follicular diameter, or growth rate of the largest follicle. In conclusion, lipid supplementation with roasted whole soybeans improved the metabolic profile of ewe lambs, with no concomitant effect on follicular dynamics or linoleic serum concentration. Except for a reduction in the number of follicular waves, the follicular dynamics were not altered by moderate FR. Despite the higher serum HDL concentrations in ewe lambs that had ovulated, the follicular development was not enhanced.