Two accelerated lambing systems, Morlam using Morlam sheep (USDA, Beltsville 1966 to 1975) and Camal using Dorset ewes (Cornell 1978 to 1981), were evaluated for first lambing ages, interlambing intervals and conception probabilities. Morlam ewes were continuously exposed to rams over the year, while Camal Dorset ewes were exposed every other month. Morlam lambs were mated as early as 367 d of ...

The 5-yr attrition of 1/4 (n = 411) or 1/2 (n = 403) Finnsheep (Finn) ewes exposed to terminal sire breeds in either an accelerated or semi-intensive annual lambing system was recorded to test the effects of system and percentage Finn on flock age structure at equilibrium. Ewes were culled for discernible ailments and failure to lamb after two consecutive non-spring exposures in yr 3, 4, or 5 o...

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...

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...

Observations were carried out at Lismore in western Victoria on the performance of two groups of 250 fine wool Merino ewes mated in spring (November) and autumn (May) respectively. A greater proportion of ewes lambing in spring lambed within 150-170 days after the introduction of the rams than ewes lambing in autumn. The duration of lambing was shorter in spring. There were no significant diffe...

Three hundred three pregnant ewes were randomly allotted to treatments in a 2 (diet) X 2 (feeding time) factorial arrangement 10 d before the first lambs were due in two lambing seasons to study the effect of time of feeding and diet on time of lambing. Behavioral activities were observed to determine if there was a relationship to time of parturition. All ewes were fed .5 kg ground whole corn ...

Granulocytic Ehrlichia infection in sheep is common in Norway in areas with Ixodes ricinus. In this study, 2 sheep flocks that had been grazing on I. ricinus infested pastures the previous season, were blood sampled after being housed indoors for nearly 6 months during wintertime. Thirty animals from each flock were examined for granulocytic Ehrlichia infection in the peripheral blood by blood ...

AIM To determine the effects of annual rainfall and farm on the efficacy of melatonin implants in improving lamb production in Merino sheep in Spain. METHODS A study was conducted on 3,871 Merino sheep on six farms over a 4-year period (2004-2007). Melatonin implants were inserted during the second half of February or early March (winter) (Melatonin group) or not (Control group). Multinomial ...

A performance data set from 376 Ripollesa purebred ewes of the experimental flock of the Universitat Autònoma of Barcelona was analyzed using a bivariate Bayesian threshold-linear model. The data set contained 1,598 litter size records and 1,699 days-to-lambing records. The model included the additive genetic effect of each animal and 3 nongenetic sources of variation: ewe age, year of lambing,...