Artificially reared ewes cannot be distinguished from natural reared ewes based on observed maternal behavior or lamb weaning weights.

Artificially rearing lambs is an important component of United States sheep production as some flocks select for increasing litter size to boost productivity. However, there is a conception among shepherds that artificially reared ewe lambs will ultimately result in poor mothers since they were not naturally raised. The objective of this study was to determine if differences in maternal behavior could be detected between ewes raised artificially and those raised naturally and if dam rearing type had an impact on lamb growth performance.

Genomic Approaches Identify Novel Gene Associations with Out of Season Lambing in Sheep.

Sheep are seasonally polyestrous, traditionally breeding when the day length shortens in the autumn. The changing photoperiod stimulates reproductive hormones through a series of chemical pathways, ultimately leading to cyclicity. Some breeds of sheep, such as the Polypay and Dorset, have been selected for reduced seasonality and can lamb year-round.

Further testing of for out-of-season reproduction in the Cornell flock and allelic frequencies compared with Romney sheep.

Sheep are seasonally polyestrous breeders, meaning they breed when day length shortens in the autumn. Ewes respond to changing day length through chemical pathways involving melatonin receptors. Some breeds, such as Dorset, are known to be less seasonal with many ewes able to breed and lamb year-round.