Burren, AlexanderAlexanderBurrenFanger, MelanieMelanieFangerJörg, HannesHannesJörg2024-11-192024-11-192023-09-0110.24451/arbor.19961https://doi.org/10.24451/arbor.19961https://arbor.bfh.ch/handle/arbor/35731In the present study, the influence of sire breed on pregnancy duration in Braunvieh (BV) and Original Braunvieh (OB) cows was investigated. Braunvieh Schweiz provided data from 2,096,865 BV and 132,731 OB cows from 2000-2021 with 14 and 11 different sire breeds, respectively. The different sire breeds were represented as follows: Angus (AN) 20'119/780, Blue Belgian (BB) 22'630/316, Blonde d'Aquitaine (BD) 28'191/316, Brown Swiss (BS) 288'845/395, Braunvieh (BV) 1'177'947/3'159, Charolais (CH) 24'828/262, Holstein (HO) 11'718/0, Eringer (HR) 2'679/101, Jersey (JE) 2'793/0, Limousin (LM) 368'229/11'451, Original Braunvieh (OB) 96'716/114'809, Pinzgauer (PI) 5'469/168, Swiss Fleckvieh (SF) 1'938/0 and Simmentaler (SI60) 44'763/974. The relationship between gestation length and sire breed was examined using a mixed linear model. The model included fixed effects calving year and month, milk linear and quadratic, calving age linear and quadratic, number of calves born by sex and sire breed, and random effects mother, sire, and farm. The longest gestation period resulted in BV and OB cows with sire breed BD (289.7 days) and (289.9 days), respectively. This was followed by PI (289.2), OB (289.2), LM (288.4) and SI (287.8) breeds in BV cows and PI (289.3), OB (289.2), LM (288.6) and SI (288.3) in OB cows. In BV cows, the sire breed HO (282.4) and in OB cows, the sire breed AN (283.2) achieved the shortest pregnancy durations. Further, both sex and the number of calves born had an influence on pregnancy duration. For a male calf, the gestation period is longer than for a female (BV: f=288.6, m=290.4; OB: f=289.8, m=291.5). Twin births result in a slightly shorter gestation period (BV: ff=283.6, mf=283.9, mm=285.3; OB: ff=284.3, mf=284.8, mm=286.0). The results show that breeders can influence the gestation length by their selection of sire breed.enSFconference_item