Effects of breed, parity and post-mating nutrition on reproductive wastage and pregnancy outcomes of Egyptian sheep

Effects of Mid-Gestation Nutrient Restriction, Realimentation, and Parity on the Umbilical Hemodynamics of the Pregnant Ewe

Previous studies have reported that nutritional restriction from days 50 to 130 applied in young nulliparous ewes reduces umbilical blood flow (UBF). We hypothesized that during restriction, UBF and fetal and placentome dimensional measurements would decrease compared to adequately fed ewes, but upon realimentation, ewes would have similar UBF as ewes that were not restricted. We also hypothesized that multiparous ewes would be more resilient to nutrient restriction compared to nulliparous ewes. In experiment 1, second-parity Dorset ewes carrying singletons were assigned to an adequate nutrition group (CON, n = 7) or a restricted (60% of CON) group (RES, n = 8), from days 50 to 90 of gestation. In experiment 2, on day 50 of gestation, adult (15-month) nulliparous (NUL; n = 12) and multiparous (MUL; n = 16) Dorset ewes carrying singletons were randomly assigned to receive 100% of NRC recommendations (CON) or 60% of CON (RES). On day 90, all ewes were fed 100% of nutritional recommendations according to body weight. Ewe body weight and conceptus measurements via ultrasonography were recorded every 10 days from days 50 to 130 of gestation. We measured 10 random placentomes, fetal biparietal and abdominal length, and kidney length and width. Doppler mode was used to obtain UBF, pulsatility index (PI), and resistance index (RI). Lamb weight and parturition problems were recorded. In experiment 1, on day 80, UBF decreased (P ≤ 0.05 means separation of unprotected F test), placentome size tended to decrease (P ≤ 0.10), and PI and RI tended to increase in RES vs. CON ewes (P ≤ 0.10). In experiment 2, there were no three-way interactions or main effects of treatments on UBF, PI, RI, and placentome size (P ≥ 0.57). There was a parity-by-day interaction (P < 0.05) for RI, but UBF was not affected by parity or diet. After realimentation, there was no effect of treatment on ultrasound measurements in both experiments. At birth, lambs and placental measurements were not different (P ≥ 0.43). Restriction from days 50 to 90 does not seem to influence umbilical hemodynamics or conceptus growth in adult white face sheep, regardless of parity.

Body condition status at mating affects gestation length, offspring yield and return rate in ewes

Abstract. The present study was planned to determine the effect of ewe body condition score (BCS) and parities on fertility, return rate, gestation length, fecundity, litter size and lamb birth weight. Data were collected from 284 heads of ewes with first to fifth parity and raised at a state farm for three consecutive (2002–2004) years. Teaser rams were used to monitor estrus twice daily in the morning and in the evening from September to October. BCSs and body weights (BWs) were recorded at mating and postpartum. The ewes, at mating time in breeding season and within first 6 h after the expulsion of fetal membranes, were divided into four groups on the basis of their BCS: thin (BCS = ≤ 2.0; n=70; 38), medium (BCS = 2.5–3.0; n=122; 142), fat (BCS = 3.5–4.0; n=72; 59) and very fat (BCS = ≥ 4.5; n= 20;17). BCSs and BWs of ewes at postpartum were highly correlated with lamb birth weight (R=0.486, P < 0.01, and R=0.130, P < 0.05, respectively). BCSs and BWs of ewes at postpartum had positive effects on lamb birth weight (Y=3.43 ± 0.10 + 0.130 + 0.047 ewe body condition score (EBCS), P < 0.01; Y= 2.92 ± 0.42 + 0.018 ± 0.009 ewe body weight (EBW), P < 0.05 kg of lamb birth weight per BCS and kilogram of ewe live weight, respectively). The fertility rate, litter size and fecundity were higher in the medium and fat groups than thin and very fat groups (χ2= 10.607, P < 0.01). The BW and BCS at postpartum affected gestation length positively (P < 0.05). Return rate or number of coitus for conception were higher (P < 0.05) in thin and very fat groups than medium and fat groups. The data revealed that the ewes with medium and fat body condition (BCS = 2.5–4.0) scores were profitable.