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/

Kidding rates were analyzed with respect to occurrence of rainfall dur ing mating and gestation, length of the breeding period, buck:doe rati o, body condition score (BCS) at mating of bucks and does, and month o f mating for 4839 indigenous crossbred goats on 46 commercial goat ope rations under extensive conditions in northeast Mexico. The kidding ra te of goats whose gestation took place during the rainy season was 93% higher (P < 0.01) than the kidding rate of goats whose gestation coin cided with lack of rainfall (30.7% +/- 2.3 and 59.2% +/- 2.0, respecti vely). Independently of the amount of rain during the mating and gesta tion of goats, kidding rate was reduced (P = 0.059) when the mating pe riod was less than 21 days. Buck:doe ratio > 1:50 did not affect kiddi ng rate (P > 0.05). Kidding rates were 42% +/- 2.4 and 48% +/- 2.3 whe n goats were exposed to bucks with a BCS of 4 and greater than or equa l to 5, respectively, (P < 0.05). Kidding rates of thin goats at matin g (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 greater than or equal to 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 rat es (32 to 45%). These results indicate that lack of rainfall during ma ting and gestation of goats under range conditions resulted in approxi mately 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 greater than or equal to 5 a t mating, if does have a BCS greater than or equal to 4, if the breedi ng period is at least 21 days and if conception takes place in Summer or Fall.