Effect of Nutritional Flushing Using Long-Term Energy and Protein Supplementation on Growth Performance and Reproductive Parameters of Doyogena Ewes in Ethiopia

SIMPLE SUMMARY: Nutritional flushing has the potential to increase reproduction in small ruminants. Utilization of locally available feed resources is imperative if smallholder farmers are to adopt improved nutritional strategies for flushing sustainably. The current experiment investigated the effect of four isonitrogenous (14.7% crude protein) rations formulated to supply low (Lo-ME) or high (Hi-ME) metabolizable energy based on enset leaf (Ensete ventricosum) and commercial concentrate and the effects on local Doyogena ewes in Ethiopia. The current finding indicated the supplementation of both enset leaf and concentrate enhanced the performance of local ewes. ABSTRACT: The objective of the study was to establish the effect of appropriate supplementation days (days -21 to +7) using four isonitrogenous (14.7% CP) diets balanced to provide low (Lo-ME) or high (Hi-ME) metabolizable energy on the body condition score (BCS), body weight (BW) change, and reproductive performances of sheep. Thirty-five Doyogena ewes (27.71 ± 2.87 kg, 2–5 years of age, BCS of 2.0–2.5) grazing on natural pasture were randomly assigned to supplementary treatments consisting of combinations of enset leaf (EL) and commercial concentrate (CC): T0 (control), T1 (250 g EL + 500 g CC: Lo-ME), T2 (400 g EL + 500 g CC; Hi-ME), T3 (500 g EL + 400 g CC; Hi-ME), and T4 (500 g EL + 250 g CC; Lo-ME). The estrous cycle was synchronized with one intramuscular injection, 5 mg PGF2α, prior to artificial insemination. The dry matter (DM) from the pasture provided 1.10–1.46 kg/day, which corresponds to the DM requirements of the ewes until late gestation. However, the pasture provided a protein content of 9.52%, which was insufficient for breeding, mid-gestation, and gestation, requiring minimums of 16.1%, 13.1%, and 14.8%, respectively. The pasture could only provide enough energy for breeding ewes with a BW of up to 30 kg. The energy provided by pasture was insufficient for ewes weighing > 30 kg at mid-gestation and gestation, providing 6.9–9.2 MJ/day, below the requirement of 11.92–16.32 MJ/day required for mid-gestation and gestation. The energy was not sufficient for large ewes weighing > 40 kg. Supplementary diets T1–T4 provided DM in the range of 1.7–2.29 kg/day. This was sufficient for AI, mid-gestation, and gestation phases. Dietary supplements increased (p < 0.01) BW during breeding and mid-gestation. During lambing, T2 and T3 increased BW (p < 0.05) compared to T4 and T1. T4 had a similar effect (p > 0.05) on BW during lambing. T1, T2, and T3 significantly increased BCS (p < 0.05). T2 and T3 increased (p < 0.05) BCS at mid-gestation, but only T2 significantly increased BCD (p < 0.05) during lambing. All dietary supplements resulted in a shorter (p < 0.05) time to the resumption of estrous and the length of estrous (p < 0.05). T1, T2, and T3 resulted in a stronger estrous response (p < 0.05). Dietary supplements enhanced (p < 0.05) the conception rate and fecundity rate. The conception rate was highest in T2 and T3 at 85.7% and 83.3%, respectively. T2 had the highest fecundity rate at 151.7% (p < 0.05). Dietary supplementation increased the rate of lambing (LR), litter size (LS), and weight of lambs at birth (LBW). The LR for treatments T2, T3, and T4 was 100% versus 66.7% in the control. T1 and T2 significantly increased (p < 0.05) LS, but T4 had a similar LS to the control. Dietary supplements T1, T3, and T4 tended to increase (p < 0.05) LBW, but T2 increased LBW significantly (p < 0.05). Supplementation (T2, T3) with 400 g enset + 500 g CC and 500 g enset + 400 g CC are promising feed supplements to increase the reproductive capacities of Doyogena ewes in Ethiopia. Energy is as important to ewe flushing as protein.