Bovine somatotropin (bST) enhances ovarian follicular and embryonic development in sheep and cattle. In the present study, the objective was to assess whether bST given 5 days before the end of progestin-based estrous synchronization improves prolificacy and lambing rate in sheep. Pelibuey ewes (n=92) exhibiting estrous cycles at regular intervals received an intravaginal sponge containing 45mg...

The use of a separate fall lambing group is feasible for spreading lamb production out through the year, especially with the use of mature animals. If each lambing group is uniquely identified, the two groups could be commingled for much of the year to make best use of feed resources. The lambing groups only need to be separate at breeding and lambing time, making management less complicated. L...

Reproductive performance and body weights of four and five-year old crossbred ewes representing five combinations of Finnsheep (F), Dorset (D) and Rambouillet (R) breeding were evaluated when lambing in the summer Oune-July, 1976). The five breed combinations represented were 1f2D, 1f2R; %D, %R; %F, 1f2D, %R; %F, %D, 1f2Rand %F, 3f4R. Breeding effectiveness of purebred and crossbred rams of Ham...

78 Ghezel and 76 Mehraban sheep were used to evaluate the effect of fat-tail docking on reproductive performance. Within two days after birth the tails of 32 Ghezel female lambs and 28 Mehraban female lambs were docked using a tight rubber ring. The lambs were allowed to reproduce for three lambing opportunities and their reproductive performances were evaluated. The effect of docking on the fe...

The effects of exogenous melatonin on reproductive performance of 737 Polypay and Polypay-cross ewes were evaluated during a late March and April breeding period. Different concentrations (2 or 10 mg) routes of administration (fed vs implanted) and durations of administration (20 or 40 d before breeding) were studied. Estrus was synchronized in all ewes using 60 mg medroxyprogesterone acetate (...

The objective of this study was to establish the risk factors associated with both lambing difficulty and lamb mortality in the Irish sheep multibreed population. A total of 135 470 lambing events from 42 675 ewes in 839 Irish crossbred and purebred flocks were available. Risk factors associated with producer-scored ewe lambing difficulty score (scale of one (no difficulty) to four (severe diff...

The aim of this trial was to evaluate the effectiveness (fertility and lambing) of priming with a single injection of progesterone plus PMSG in anovulatory lactating Sarda ewes subjected to the ram effect (RE) in spring. Thirty ewes (P4 group) were i.m. injected with 30 mg progesterone and 500 IU PMSG 36 h before ram introduction (d 0). This treatment was compared to a 12-day treatment with flu...

The effects of progestogen-gonadotropin treatment on estrous response, ovulation rate and lambing response of crossbred ewes were examined at two times during the anestrous season (May-June and July-August). Each ewe group was treated with progestogen pessaries for 16 days and injected with 750 IU pregnant mare serum gonadotropin (PMSG) on days 17 and 32 to induce two consecutive estrous period...

Increased fecundity and improved feed management have doubled the number of lambs born in any threeday period spring since 1990. Four farmer catchment groups were engaged to investigate options that farmers may use reduce impacts weather at lambingtime. After workshops identified potential mitigations, a lamb survival model was developed using data from literature. This applied daily time steps...