Anestrous ewes respond to the introduction of rams with either an ovulation within 2-3 days that may be followed by luteal phases of normal or short length, with delayed ovulations (5-6 days later), or with the luteinization of follicles. The aim of this work was to study the relationship between the growth status of the largest follicle present when rams are introduced and the type of ovarian ...

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 effects of fat supplementation and weaning system on commercial milk yield and milk composition were determined on 129 East Friesian crossbred ewes. Prior to lambing, ewes were randomly assigned to one of two weaning systems. The DY1 system involved weaning of ewes from their lambs within 24 to 36 hr post-partum and then twice-daily machine milking. In the MIX system, ewes had access to the...

The objectives were to determine the effects of short-term feeding of a toxic endophyte (Neotyphodium coenophialum)-infected tall fescue seed (Festuca arundinacea, cultivar 'Kentucky 31') on fecal shedding and intestinal concentrations of Escherichia coli O157:H7 and the concentrations of prolactin, cortisol, and NEFA in experimentally inoculated ewes. Twelve ewes (mean BW = 46 +/- 2 kg) were f...

First cross Booroola Merino x Romney (B x R) ewes born in 1975, 1976, 1978 and 1979 were classified as being heterozygous (F+) or non carriers (++) for the Booroola fecundity gene. Their performance as hoggets (< 1 year of age) I and to six years of age (1975 and 1976 bornonly) was compared with contemporary Romney (R) ewes. As hoggets, the F+ ewes had ovulation rates about 0.5 higher than ++ B...

We studied the possible effects of bacterial populations within the teat duct, in the pathogenesis of ovine mastitis. In experiment I, 32 ewes were allocated into group A (ewes from which we isolated (+++ growth) coagulase-negative staphylococci), B (ewes from whose duct we isolated (+ growth) coagulase-negative staphylococci) or C (ewes from which we isolated Bacillus spp.) and subdivided into...

Maternal nutrient restriction from early to midgestation can lead to fetal growth retardation, with long-term impacts on offspring growth, physiology, and metabolism. We hypothesized that ewes from flocks managed under markedly different environmental conditions and levels of nutrition might differ in their ability to protect their own fetus from a bout of maternal nutrient restriction. We util...

Performance of 1/2-Suffolk, 1/2-Rambouillet (Western) and 1/2-Suffolk, 1/4-Rambouillet, 1/4-Finnsheep (1/4-Finn) ewes was compared in three different lamb production systems over 3 yr. System 1 (56 ewes) involved late fall lambing over 84 d. System 2 (51 ewes) involved January and February lambing for 60 d. System 3 (47 ewes) involved March and April lambing for 45 d. Pregnancy rates for yearli...

The reproductive performance of 255 Rambouillet (R), Dorset (D), Finnsheep (F) and F1 ewes born in 1978-1979 (group I) and 1979-1980 (group II) and managed in a semiconfinement fall/winter lambing system was evaluated through 4 yr of age of all ewes and through 5 yr for a portion of group I ewes. Ewes were with rams from approximately May 1 to late September each year, with a 2-wk break late in...

Causes of reproductive loss in ewes synchronized and mated during the anestrous season and during the normal breeding season were compared with those for natural cyclic ewes mated in season. Synchronization of ewes in season and out of season with progestogen: pregnant mare serum gonadotropin (PMSG) increased ovulation rate, but the percentage of ewes ovulating did not differ from that noted fo...