EFFECT OF BODY CONDITION, SEASON OF ESTROUS INDUCTION AND FIXED TIME ARTIFICIAL INSEMINATION ON CALVING RATE OF LOCAL THRABAM CATTLE IN BHUTAN

Abstract

Response and calving rates of local Thrabam heifers and cows artificially inseminated in induced estrous (heat) was assessed. A total of 298 animals in three Agro- Ecological Zones of Samtse (Tading) and Tsirang (Barsong & Sergethang) were inseminated on induced estrous and followed up till animals calved. Results indicated that calving rate was 12.08% when inseminated on induced estrous (n=36/298) as compared to 37.5% (n=6/16) when animals were inseminated in natural estrous. Further, Thrabam cows/heifers with average Body Condition Score (BCS) of 2.8 (n=41) had significantly higher response to hormonal treatment, conception and calving (p<0.000) than animals with BCS less than 2.4 indicating good health/better plane of nutrition are prerequisite for birth of more calves when inseminated on induced estrous. Besides, estrous induction/ estrous synchronization with hormonal treatment (TRIU-B) and insemination during winter produced less calves (14.2% calving) than estrous induced and inseminated in summer (31.5% calving) in same cattle type. This indicates that seasonal variation of environmental condition alters conception/calving. Hence, Artificial Insemination of cattle on induced estrous in Bhutanese environment will be more conducive in summer when weather is favorable for adequate access to green forages by animals. Thrabam synchronized and inseminated during same season had lower conception than exotic dairy breeds (Jersey & Jersey cross). Study concludes that estrous induced in animals using hormonal drugs does not necessarily result in conception even when animals are inseminated by skilled Technicians. Hence, selection of dairy cattle with optimum body condition score, cattle breed/type, choosing of right season of the year for inducing estrous and insemination is necessary for better outcome of such interventions.