Influence of season and environment on fertility of goats in a hot-arid environment

Conception rate and prolificacy of dairy and crossbred goats under intensive conditions in an arid environment of northern Mexico (26 degrees 06' 15" N; maximum temperature throughout the year 12-42 degrees C, mean annual precipitation 186 mm, and RH <40% year-round) were examined with respect to season of mating, ambient temperature and rainfall at mating. The database contained 4194 natural services. Conception of goats inseminated with average maximum ambient temperatures >34 degrees C was significantly higher (P<0.01) than conception of goats inseminated when the average maximum temperature 3 days before breeding was <34 degrees C. The warmest season favoured conception rate (70% in spring; P<0.01) as compared to cooler seasons (62% and 64% for summer and autumn, respectively). Conception rate of goats bred when rain was present was 14 percentage points lower (P<0.01) compared to mating with no rain. When maximum temperatures on the day of mating were >34 degrees C, cooler temperatures 1 to 3 days before or after the day of mating were associated with a significant increase in the number of kids born. When the maximum temperature at mating was >36 degrees C, prolificacy for goats exposed to higher or lower temperatures 1 day before mating was 1.56 and 1.65, respectively (P<0.05). Similarly, when the maximum temperature at mating was 34-36 degrees C, prolificacy was higher for goats exposed to cooler temperatures as compared to warmer temperatures 1 day (1.64 v. 1.49; P<0.01) or 3 days (1.63 v. 1.48; P<0.01) after mating, with respect to the temperature on the day of mating. Conclusions were that conception rate was not compromised in non-lactating Alpine, Toggenburg, Granadino and Nubian goats subjected to high environmental temperature in an arid region, but the occurrence of rain at mating depressed breeding efficiency of these animals. Additionally, an increment in litter size is expected with cooler temperatures before or after hot days at time of mating.