Plasma progesterone concentrations during pregnancy and pseudopregnancy and onset of ovarian activity post partum in indigenous goats in Zimbabwe.

Eight pregnant does were housed individually and fed a hay and concentrate diet throughout pregnancy and lactation. The mean gestation period was 146.7 +/- 3.0 days, with a twinning rate of 75 per cent. Mean body condition scores improved from 2.4 +/- 0.2 to 2.8 +/- 0.2 over the first 80 days of gestation and were maintained at 2.8 until 45 days before kidding. From then until kidding, mean scores fell to 2.2 +/- 0.2. Plasma progesterone concentrations during pregnancy rose significantly from 3.91 +/- 0.51 ng/ml on day 40 to 5.96 +/- 0.51 ng/ml on day 60 (P < 0.05) and remained high until 5 days before kidding. Three pseudopregnant does had similar progesterone profiles to pregnant does over the first 80 days, but the rise around day 35 to 40 was not significant and progesterone concentrations returned gradually to basal levels after day 100. The same 8 does, together with an additional 4 does which had been brought inside 60 to 70 days before kidding, were used to study onset of ovarian activity post partum. The twinning percentage was 83 per cent. Mean body condition score at parturition was 2.2 +/- 0.1. By day 35 post partum, mean condition scores had fallen to 1.9 +/- 0.1, and mean weights from 36.9 +/- 1.9 kg at kidding to 32.1 +/- 2.0 kg. Ovarian cyclicity was resumed just before mean scores and weights started to improve. The mean interval from kidding to onset of oestrous cycles was 97.3 +/- 9.5 days. This coincided with mean time to weaning which was 99.5 +/- 5.5 days.(ABSTRACT TRUNCATED AT 250 WORDS)