Ewes from lines selected for high and low reproductive rate and a control line bred and selected randomly were endoscopically examined 3 to 5 d after breeding to determine ovulation rates in the fall of 1985, 1986 and 1987. Fertility (ewes lambing per ewe exposed), lambing rate (lambs born per ewe exposed) and litter size (lambs born per ewe lambing) were evaluated at lambing in the spring of e...

the effect of crossbreeding between ghezel and mehraban on growth performance and carcass characteristics was studied for two consecutive years using 162 purebred and crossbred lambs. the four groups of lambs involved in the study were purebred mehraban (mm), purebred ghezel (gg), crossbred ghezel ram×mehraban ewe (gm) and crossbred mehraban ram×ghezel ewe (mg). the lambs were fed with grazing ...

characteristic of the udder, milk traits and their relationship were investigated in 32 awassi ewes raised in a commercial flock. commencing one month after lambing milk yield was recorded at monthly intervals until the ewes were dried. also, the udder traits were measured, including udder width, udder circumference, udder length, distance between teats and length and diameter of both teats. re...

This study examined the effects of melatonin and level of nutrition on embryo yield during anestrous and breeding season. Adult Rasa Aragonesa ewes were assigned randomly to one of the four treatment groups in two experiments using a 2x2x2 factorial design. Individuals were treated (+MEL) or not treated (-MEL) with a subcutaneous implant of melatonin for 42d (Melovine, CEVA) and fed 1.5 (contro...

The present study investigated the effect of maternal vitamin E and fatty acid supplementation on lamb antioxidant status. Forty-eight ewes were fed one of four concentrate diets supplemented with a basal (50 mg/kg) or supranutritional (500 mg/kg) level of vitamin E plus a source of either saturated fat (Megalac; Volac Ltd, Royston, Hertfordshire, UK) or long-chain PUFA (fish oil) from 6 weeks ...

Parental care promotes offspring survival and, for livestock species, this care is provided solely by the mother. Maternal behaviour in the sheep has been exceptionally well-studied compared with other species and many of the underpinning biological processes leading to the expression of maternal care are known. In this review the current state of play with regard to the biology of maternal car...

Mating behavior is known to be heritable in several species, but it is not known if selection schemes for ewe reproductive traits affect mating behavior of rams. Therefore, our objectives were to determine if divergent (high vs low index) selection of a female reproductive trait (lambs born divided by age of ewe minus one) affects mating behavior patterns of male offspring during training to se...

Ability to select service sires that minimize partial or complete losses of pregnancy could have major economic impacts in sheep production systems. This study tested the null hypothesis that survival of potential progeny did not vary with breed type of service sire or among individual rams. Data included 980 ewes on 10 farms; each ewe was pregnant to 1 of 67 rams of 12 breeds. Number of concep...

Introduction: Gonadotropin inhibitory hormone (GnIH) and Agouti-related peptide (AgRP) are orexigenic peptides expressed in the arcuate nucleus (Arc) of the hypothalamus in the ewe. In addition, effects of GnIH and AgRP on the regulation of gonadotropin releasing hormone secretion have been shown in some mammals. The objective of the present study was to investigate the coexpression of GnIH ...