Haemato-biochemical responses, worm burdens and Haemonchus contortus ultrastructural changes in lambs fed diets containing graded inclusion levels of sericea lespedeza

Abstract

Context Globally, sheep productivity is constrained by scarcity of high-quality feed and haemonchosis. These challenges may simultaneously be addressed by valorisation of nutraceutical forage legumes such as sericea lespedeza (SL) into sheep diets. Aim The current study determined the effects of feeding diets containing increasing inclusion levels of SL (0%, 6.25%, 12.5%, 18.75% and 25%) as replacement for lucerne on haematological, biochemical, and parasitological parameters in Haemonchus contortus-infected and non-infected lambs. Methods Bodyweights, body condition scores (BCS), FAMACHA© scores, faecal worm egg counts (FWEC), and haematological and biochemical parameters were recorded from 80 Dohne Merino intact male lambs assigned to diet-by-infection status-based treatments in a completely randomised design, with a 5 × 2 factorial arrangement of treatments comprising of eight lambs per treatment during a 42-day feeding trial. Adult worms were collected, enumerated, and their ultra-structure was evaluated using scanning electron microscopy after slaughter. Results Diet, and diet × infection status had no effects on red blood-cell parameters of the lambs (P > 0.05). Eosinophils were affected by diet × infection status, being highest in non-infected lambs fed the control diet and lowest in infected lambs fed the 25% SL diet (P ≤ 0.05). Serum albumin, calcium and body condition scores declined (P ≤ 0.05) with increasing inclusion levels of SL in the diet. There was no influence of diet on lamb bodyweights, FAMACHA© scores, FWEC, and worm burdens. Dietary increments of SL disrupted the structural integrity of the head (χ2 = 28.43; ϕc = 0.493; P ≤ 0.05) of adult worms. Conclusions Sericea lespedeza may replace lucerne up to 25% in lamb feedlot diets, with minor negative effects on haematological and biochemical parameters, but offers little benefits for modulating Haemonchus contortus infection. Implications Beneficiation of biologically active alternative feed resources such as sericea lespedeza could help farmers adapt better to market changes through the development of enhanced livestock feed and pharmaceutical products, which could help alleviate losses associated with impoverished nutrition and gastrointestinal health of lambs.