Effects of body condition, length of breeding period, buck:doe ratio, and month of breeding on kidding rates in goats under extensive conditions in arid zones of Mexico

Abstract

Kidding rates were analyzed with respect to occurrence of rainfall during mating and gestation, length of the breeding period, buck:doe ratio, body condition score (BCS) at mating of bucks and does, and month of mating for 4839 indigenous crossbred goats on 46 commercial goat operations under extensive conditions in northeast Mexico. The kidding rate of goats whose gestation took place during the rainy season was 93% higher ( P < 0.01) than the kidding rate of goats whose gestation coincided with lack of rainfall (30.7% ± 2.3 and 59.2% ± 2.0, respectively). Independently of the amount of rain during the mating and gestation of goats, kidding rate was reduced ( P = 0.059) when the mating period was less than 21 days. Buck:doe ratio > 1:50 did not affect kidding rate ( P > 0.05). Kidding rates were 42% ± 2.4 and 48% ± 2.3 when goats were exposed to bucks with a BCS of 4 and ≥ 5, respectively, ( P < 0.05). Kidding rates of thin goats at mating (BCS 3) were around 20% lower ( P < 0.01) than rates of goats with BCS of 4 or greater. On the other hand, kidding rates of does with BCS of 4 and ≥ 5 did not differ significantly ( P > 0.05). The highest kidding rates (52 to 58%) occurred with matings from June to November (rainy season), whereas matings in Winter and Spring (dry season) resulted in a drastic reduction ( P < 0.01) in kidding rates (32 to 45%). These results indicate that lack of rainfall during mating and gestation of goats under range conditions resulted in approximately 50% reduction in kidding rates, compared with gestations during the rainy season. Also these results demonstrate that higher kidding rates could be achieved if bucks have BCS ≥ 5 at mating, if does have a BCS ≥ 4, if the breeding period is at least 21 days and if conception takes place in Summer or Fall.