LH response to GnRH infusion in postpartum, fall-lambing ewes subjected to prepartum energy restrictions.
Fall-lambing western range ewes were fed either a high-or low-energy ration the last two months of gestation and were fed protein and energy in excess postpartum. GnRH was infused for 10 hours on day 5 or 26 postpartum. Blood samples were collected at 20-minute intervals during infusion and radioimmunoassayed for LH. Net weight change from day 60 prepartum to day 1 postpartum was 0.67 +/- 1 kg vs. -6.9 +/- 1.5 kg (mean +/- SE) for the high-and low-energy groups, respectively (P < 0.05). Nutritional treatment had no effect on LH response at either day 5 or day 26 postpartum, althoughthe day 26 LH response to GnRH was greater (P < 0.05) than the day 5 LH response. LH response was greater (P < 0.05) in ewes that gained weight prepartum vs. ewes that lost weight prepartum, but only in ewes infused on day 5 postpartum.
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Texas Agricultural Extension Service Texas A&M University System Ft. Stockton, TX 79735 USA.
Dunn
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Kaltenbach
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