Climate zone influences the effect of temperature on the day of artificial insemination on fertility in two Iberian sheep breeds

ABSTRACT

The aim of this study was to determine the effect of temperature on the day of artificial insemination (AI) on fertility, and to study how climate zone of the farm may modify this effect, in two breeds of sheep that are reared on the Iberian Peninsula on four farms located within one of three climate zones, based on the Köppen Climate Classification. A total number of 1,931 AI were studied from Spanish farms of the Rasa Aragonesa (RA) (July) and Churra (CH) (June) breeds. Farms were categorized as Köppen BSk (Farm BSkRA; n=229), and Köppen Cfb (Cfb-RA; n=372), Köppen Csb (Csb-CH; n=908), and Köppen Cfb (Cfb-CH; n=422). Mean, maximum, and minimum temperatures (°C) were recorded, and thermal amplitude (maximum-minimum temperatures) calculated. Each set of temperature data was distributed between percentile-groups (≤50% and >50%), below or above the median. Temperatures at AI were higher (P50 percentile groups indicated that inseminations performed when temperatures were within the >50 percentile had a higher proportion (P1 for one or more of the meteorological variables under study; meanwhile, in the other two climates, OR were 0.05). In conclusion, the effects of temperature on fertility after AI differed depending on the climate zone in which the flocks were reared. The results have implications for the scheduling of insemination dates to achieve the maximal performances.