TY - JOUR
T1 - Relationships among Puberty, Muscle and Fat, and Liveweight Gain during Mating in Young Female Sheep
AU - Rosales Nieto, Cesar
AU - Ferguson, M.B.
AU - Thompson, H.
AU - Briegel, J.R.
AU - Macleay, C.A.
AU - Martin, Graeme
AU - Thompson, A.N.
PY - 2015
Y1 - 2015
N2 - © 2015 Blackwell Verlag GmbH. Contents: Greater depths of muscle are associated with better reproductive performance in ewe lambs, but, in adult ewes, reproductive performance also seems to vary with liveweight gain during the mating period. Therefore, in a large field study with Merino ewe lambs, we tested whether the relationships among eye muscle depth (EMD), fat depth (FAT) and reproductive performance depend on liveweight gain during the mating period. We selected lambs with a wide range in phenotypic values for depths of eye muscle (EMD) and fat (FAT) and assigned them to dietary treatments designed to achieve low (LOW, n = 244) or high (HIGH, n = 237) rates of liveweight gain during a 28-day mating period. The LOW treatment maintained live weight, whereas the HIGH treatment gained 179 ± 3.8 g/day (p <0.001). From those ewe lambs that attained puberty, first oestrus was detected at live weight 37.8 ± 0.2 kg and age 232 days. The proportion of ewes that attained puberty increased with EMD (p <0.01). Ewes from the HIGH treatment were more fertile (pregnant ewes per 100 ewes exposed to rams) and had a higher reproductive rate (foetuses in utero per 100 ewes exposed to rams; p <0.001) than those from the LOW treatment. Fertility and reproductive rate were positively correlated with weight gain during mating as well as live weight at the start of mating, FAT and EMD (p <0.05 to
AB - © 2015 Blackwell Verlag GmbH. Contents: Greater depths of muscle are associated with better reproductive performance in ewe lambs, but, in adult ewes, reproductive performance also seems to vary with liveweight gain during the mating period. Therefore, in a large field study with Merino ewe lambs, we tested whether the relationships among eye muscle depth (EMD), fat depth (FAT) and reproductive performance depend on liveweight gain during the mating period. We selected lambs with a wide range in phenotypic values for depths of eye muscle (EMD) and fat (FAT) and assigned them to dietary treatments designed to achieve low (LOW, n = 244) or high (HIGH, n = 237) rates of liveweight gain during a 28-day mating period. The LOW treatment maintained live weight, whereas the HIGH treatment gained 179 ± 3.8 g/day (p <0.001). From those ewe lambs that attained puberty, first oestrus was detected at live weight 37.8 ± 0.2 kg and age 232 days. The proportion of ewes that attained puberty increased with EMD (p <0.01). Ewes from the HIGH treatment were more fertile (pregnant ewes per 100 ewes exposed to rams) and had a higher reproductive rate (foetuses in utero per 100 ewes exposed to rams; p <0.001) than those from the LOW treatment. Fertility and reproductive rate were positively correlated with weight gain during mating as well as live weight at the start of mating, FAT and EMD (p <0.05 to
U2 - 10.1111/rda.12542
DO - 10.1111/rda.12542
M3 - Article
C2 - 25990918
SN - 0936-6768
VL - 50
SP - 637
EP - 642
JO - Reproduction in Domestic Animals
JF - Reproduction in Domestic Animals
IS - 4
ER -