Appraisal of cowpea (Vigna unguiculata) hay as a replacement for noug seed (Guizotia abissynica) cake in the ration of Gumuz lambs in Ethiopia

Abstract Background The objective of this study was to evaluate the replacement value of cowpea (Vigna unguiculata) hay for noug seed (Guizotia abissynica) cake on dry matter (DM) and nutrient intake, nutrient digestibility, body weight change, carcass characteristics and economic feasibility of the feeding regime of Gumuz lambs. Methods The study was conducted using 25 yearling intact male lambs with an initial body weight of 18.26 ± 0.63 kg (mean ± SD).The lambs were assigned into five treatments: (T1) 272.3 g noug seed cake (NSC); (T2) 200.73 g NSC + 105.55 g cowpea Sewinet variety hay (CSH); (T3) 134.3 g NSC + 211.86 g CSH; (T4) 66.31 g NSC + 313.79 g CSH and (T5) 417.98 g CSH on DM basis. The experiment was conducted using a randomized complete block design (RCBD), and lambs were blocked based on their initial body weight. The feeding trial was conducted for 90 days followed by 7 days of digestibility trial. Natural pasture hay was treated with molasses solution for improvement of palatability and digestibility and offered for all experimental lambs in ad libitum. Results The crude protein (CP) contents of natural pasture hay (NPH), CSH and NSC were 4.99, 18.31 and 36.5%, respectively. The total DM intakes of lambs (P < 0.05) increased at higher levels of CSH supplementation. The CP intake decreased with increasing levels of CSH supplementation. Digestibility of DM, organic matter (OM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) was improved by a higher level of CSH supplementation but CP digestibility was not affected by supplementation of CSH. The average daily gain (ADG) showed significant difference (P < 0.05) among treatments. Similarly, the feed conversion efficiency (FCE) was significantly different (P < 0.05) among treatments; higher FCE was recorded at T1 but lower was at T3 and T4. The hot carcass weight (HCW) showed significant difference (P < 0.05) among treatments; higher value was observed in T5 (9.36 kg), but the smallest value was recorded for lambs on the T3 (7.36 kg). The higher dressing percentage (DP) on empty body weight basis was recorded in three treatment (T1 = T4 = T5) groups compared with (T2 > T3) treatments. Significantly higher (P < 0.05) rib‐eye area was achieved at a high level of CSH and sole NSC supplemented lambs. The economic feasibility showed that the highest profit was achieved in T5. Conclusion From the present study, it was concluded that CSH could be used for supplementation of protein source feed for body weight gain for Gumuz lambs by replacing high‐cost concentrates in a native hay‐based basal diet. As a final point, CSH supplementation was recommended as replacement of NSC at 417.98 g CSH (T5) for better biological performance as well as economic value.