The objective of this study was to test the null hypothesis that heat production (HP) was equivalent between Suffolk and Texel ewes at common fasted BW and at common ages. Open-circuit respiration calorimetry was used to estimate HP in 48 Suffolk and 48 Texel ewes at eight ages (10, 15, 20, and 28 wk of age and 1.5, 2.5, 3.5, and 4.5 yr of age). Sheep were individually penned in an environmenta...

Previous research has shown that the proportion of seasonal anoestrous ewes that ovulate in response to the introduction of rams ('ram effect') is dependent upon pheromonal and sexual behavioural stimuli emitted by the rams. Close contact with oestrous ewes is likely to increase the rams' libido and level of testosterone secretion, which in turn has been suggested to positively influence the pr...

This study describes responses to artificial infection with Haemonchus contortus in ewes and lambs of 50% Dorset, 25% Rambouillet, and 25% Finn-sheep ancestry and provides estimates of genetic parameters for measures of parasite resistance. One hundred ninety-eight ewes out of 64 sires, and 386 lambs out of 25 sires were evaluated in autumn and spring of 2 yr. Ewes were dewormed shortly after w...

Elevated dietary nitrate (NO3-) is associated with production losses in ruminant livestock, resulting in substantial economic losses incurred by producers. Severe drought, fertilization practices and poorly maintained pastures increase the risk of elevated NO3- intake among cattle and sheep. Nitrate is metabolized to nitrite (NO2-) in the rumen and further reduced to ammonia. Ruminants consumin...

An experiment was conducted to determine whether controlled internal drug release devices-type G (CIDR-G) could be used in conjunction with the ram effect to advance the breeding season and lambing and thereafter could be reapplied to stimulate breeding of ewes to produce a second lambing in late summer. Finn crossbred and Columbia ewes were treated with CIDR-G from July 6 to 18. Rams, which ha...

The objectives of this study were to determine if exposing seasonally anovular ewes to rams would alter patterns of cortisol concentrations, and if these changes are associated with changes in characteristics of LH concentrations. Seasonally anestrous ewes were assigned to be exposed to rams (RE; n=11) or wethers (NE; n=12). Blood samples were collected at 15-min intervals beginning 120 min bef...

In Exp. 1, ovulation rate was measured in three groups of Romanov ewes given two injections of 600 i.u. PMSG 3 weeks apart with the ewes intact (Group I, N = 8), a similar treatment with the ewes intact at the first injection and unilaterally ovariectomized at the second (Group II, N = 8), or unstimulated ewes which were hemispayed at the same time as Group II ewes (Group III, N = 6). In Exp. 2...

The influence of copper upon some physiological parameters and reproduction in ewes was studied. Four groups of animals were investigated: 1/ control ewes (untreated); 2) ewes receiving copper as a supplement over the recommended amount of copper in food (10, 25 or 50 mg Cu/ewe/day); 3/ control, superovulated ewes; and 4) ewes treated with 50 mg copper during one month and then superovulated. A...

Two experiments were performed to determine the effectiveness of different progestogens contained in intravaginal devices, different doses of eCG and subsequent hCG treatment on the reproductive performance of estrus-induced mature Lori ewes. In the first experiment, 88 ewes were allocated into two groups, and were treated with either fluorogestone acetate (FGA) sponges or Controlled Internal D...

Human chorionic gonadotropin (hCG) may boost progesterone production and attenuate maternal-immune response against concepti in ewes, increasing prenatal survival. The present study examined effects of repeated hCG administration after mating on serum progesterone concentration and complete blood counts (CBC) during early gestation, as well as offspring numbers at parturition. Fifty-six ewes we...