Risk factors involved in conception, abortion, and kidding rates of goats under extensive conditions

Multiple logistic regressions were used to investigate the effect of body weight, certain body measurements, lactation, parity, polledness, and certain blood minerals and metabolites at mating on the reproductive performance of does. Data were obtained from 374 brucellosis-free mixed-breed does of different ages and parities and kept under natural range conditions. Body condition score (BCS) was not a risk factor regarding pregnancy, but compared to all other does, the thinnest goats (BCS < 1.5; 5-point scale) were nine times more likely to abort. Trends were noted for the youngest does to have a higher risk of aborting (four times higher). Polled goats had a 1.5 times higher chance of aborting. Goats with serum Ca concentrations >10 mg per 100 ml and urea >10 mg per 100 ml were twice as likely to abort than goats with lower levels of these blood components. Goats with serum glucose concentrations >60 mg per 100 ml had twice higher odds of kidding, compared to goats with lower serum glucose concentrations. Primiparous does were three times less likely to kid than multiparous does. Other variables significantly (P < 0.05) associated with kidding rate were BCS, serum urea, creatinine levels and polledness. Pregnancy was more likely to occur in goats with serum Mg levels >4 mg per 100 ml, serum urea between 6 and 10 mg per 100 ml, serum glucose >60 mg per 100 ml, and serum Ca >10 mg per 100 ml. Results of this study emphasize the importance of removing risk factors such as low body energy reserves, low serum glucose levels, young does, polled animals and low Mg and Ca intake at mating as a possible means for improving the reproductive performance of goats under natural range conditions. © 2004 Elsevier B.V. All rights reserved