Pregnancy-associated glycoprotein and progesterone profiles during pregnancy and postpartum in native goats from the north-east of Brazil

Abstract

Pregnancy diagnosis is a critical procedure for monitoring goat reproductive performance. In the present investigation, pregnancy-associated glycoprotein (PAG) profiles during pregnancy and first month postpartum, as well as progesterone (P 4) concentrations throughout pregnancy, were determined in native goats from the north-east of Brazil. A total of 30 goats (Moxoto, n = 19 and Caninde, n = 11) were used. Peripheral blood was collected on days 0 (Day 0 = AI), 11, 16, 18, 20, 24 and 30 after AI. Samples were subsequently collected every 2 weeks until day 145, and weekly during the first month postpartum. The levels of PAG and P 4 were determined by radioimmunoassay (RIA). The profiles of PAG were not different between the breeds throughout pregnancy. However, a significant effect of the week of pregnancy ( p < 0.01) and the number of fetuses ( p < 0.05) in PAG concentrations were found. Lower concentrations of PAG were observed during weeks 1 and 3, compared to the rest of the gestation. Thereafter, there was a significant ( p < 0.05) increase in PAG concentrations from week 5 to 7 and a significant decrease ( p < 0.05) in week 9. The PAG concentrations remained relatively constant until week 17, and finally decreased slowly until parturition. After parturition, PAG concentrations decreased rapidly, and continued to decrease until week 4. During pregnancy, mean P 4 concentrations had weekly variations among the animals ( p < 0.01) and the period of pregnancy ( p < 0.01), but P 4 was not affected by the breed or number of fetuses. These results indicate that PAG and P 4 concentrations were similar for Caninde and Moxoto goats and that, for both the breeds, the stage of pregnancy and the number of fetuses could influence PAG production.