Abstract
Abstract
The hypothesis that prepubertal ewe lambs are metabolically different from postpuberal ewes was tested. Ovariectomized ewes (4 years of age; n = 4) and lambs (6 months of age; n = 4) were fasted for 72 hr. Serum concentrations of insulin, glucose, urea nitrogen, and free fatty acids (FFA) were measured in blood samples taken at 6-hr intervals between 30 hr before and 72 hr after feed removal. Serum concentrations of urea nitrogen and glucose were not different (P > 0.20) between age groups before fasting. Serum concentrations of insulin in ewes increased toward the end of the prefast period whereas those in lambs did not (age × time, P < 0.01). Serum concentrations of FFA in ewes tended to be lower (P < 0.07) than those in lambs prior to fasting. During fasting, concentrations of insulin decreased (P < 0.02) over time in ewes and lambs and did so in a similar manner (age × time, P > 0.70). Urea nitrogen increased (P < 0.0001) in both fasted ewes and fasted lambs in a comparable manner (age × time, P > 0.20). Concentrations of glucose during fasting were not significantly affected (P > 0.90) by age. There was a tendency (P = 0.08) for concentrations of glucose to change over time but the pattern did not appear to be related to fasting. During fasting, concentrations of FFA tended to be higher (P < 0.07) in lambs than in ewes and increased (P < 0.0001) in both groups in a similar fashion (age × time, P > 0.10). The findings herein suggest that turnover of FFA in lambs may be slightly greater than that in ewes during the fed and fasted states.
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