Abstract The management of sheep reproduction requires the induction and synchronization estrus cycle ovulation for ewe out-of-season and/or synchronized lambing. These managements are based on insertion an intravaginal device controlled internal drug release (CIDR or sponge) then administration a hormonal injection, such as PMSG, eCG, hCG, GnRH. This study aimed to compare impact CIDR sponges,...

Effects of environmental factors such as ewe age, season of exposure, and time from lambing to exposure on fertility were evaluated using records on 1,084 Dorset ewes in the STAR accelerated lambing system. The STAR program consisted of five 30-d concurrent breeding and lambing periods per year beginning on January 1, March 15, May 27, August 8, and October 20. Fertility in the flock changed in...

Reproductive performance of four, five and six-year old crossbred ewes representing six combinations ofFinnsheep (F), Dorset (D), Rambouillet (R), and White Face Western (WFW) breeding were evaluated when lambing in the winter (February-March, 1977) and in the fall (October-November, 1977). The six breed combinations represented were 3fsF, 5fsWFW; %F, 1f2D, %R; %F, %D, 1f2R; %F, %R; 1f2D, 1f2R;...

Pregnancy disease (pregnancy toxemia, twin lamb disease, lambing sickness, lambing paralysis or lambing ketosis) typically affects ewes during the last 2 to 4 weeks of pregnancy and is a common cause of ewe and lamb loss in Michigan flocks. Overconditioned or thin ewes, usually pregnant with multiple fetuses, are most commonly affected and clinical cases are generally limited to older ewes duri...

The aim of the study was to evaluate effect body condition score (BCS) at lambing over resumption ovarian and estrous postpartum activity in lactating Pelibuey ewes. Twenty ewes were assigned two groups, according BCS lambing: Low (LBC, n = 10) High (HBC, 10). Ovarian activities daily monitored from day 3 until first or 90 days postpartum. Continuous variables analyzed using Student´s t test bi...

Ewe productivity is synonymous with annual litter-weight weaned (LWW) per ewe exposed to rams for breeding, and LWW is largely a function of number of lambs born (NLB) and weaned (NLW). Selecting for LWW should increase litter size and numbers of ewe-ram co-twins. Thus, we used historical records to determine whether sex of co-twin affected lifetime productivity of twinborn ewes. United States ...

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...

Pregnancy rate following artificial insemination (AI) in sheep is variable depending on several factors. The Churra breed (milk breed of the North-West of Spain) yields lower fertility results compared with other local and European breeds (Manchega, Latxa, Merino, Lacaune, Sarde, etc.). In this work we studied the influence of many factors on the fertility of the Churra breed (insemination tech...

Body condition was scored at lambing (BCSL) on 101 mature (4 to 7 yr old) Polypay ewes and related to colostral immunoglobulin G (IgG) concentration and lamb performance. Colostrum samples were collected from each ewe within 12 h of lambing and litters of more than two lambs were reduced to two within 2 h of lambing. Colostral IgG concentrations decreased rapidly with time (b = -3.28; R2 = .213...