In vitro and in vivo evaluation of some tree leaves as forage sources in the diet of Baluchi male lambs

Abstract

This study aimed to evaluate the potential use of some tree leaves including almond (Prunus amygdalus L.), pomegranate (Punica granatum L.), apple (Malus domestica Borkh.), pistachio (Pistacia vera L.), and walnut (Juglans regia L.) compared to whole plant alfalfa (Medicago sativa L.) in sheep feeding through in vitro experiments in order to screening of the resources and then selecting the most suitable candidate resource for in vivo experiment. Chemical and mineral composition, in vitro gas production, and fermentation parameters of leaves were also determined. The results indicated that the crude protein (CP) ranged from 12.12 % for almond leaves (AL) to 16.77 % for alfalfa, on dry matter (DM) basis. The highest and lowest neutral detergent fiber (NDF) content was observed in alfalfa (48.50 %) and pomegranate leaves (26.45 %), respectively (P < 0.0001). The range of metabolisable energy (ME) differs from 6.76 for pomegranate leaves to 10.50 MJ/kg DM for AL. Alfalfa and AL exhibited the lowest (9.53 g kg DM) and the highest calcium (44.15 g/kg DM) concentration, respectively (P < 0.0001). The highest true organic matter (TOMD) and dry matter digestibility (TDMD) (88.44 and 87.88 %, respectively) was also obtained in AL (P < 0.0001). It was found that AL had the highest potential gas production, and total volatile fatty acids (VFA) values of 61.05 ml/200 mg DM, and 48.33 mmol/L, respectively (P < 0.0001). In in vivo experiment, the effects of partial substitution of dietary forage with AL at 0, 5.8, 11.5, and 23 % of diet DM on growth performance, nutrient digestibility, ruminal fermentation, and blood metabolites were investigated using thirty-two Baluchi male lambs [28 ± 1.5 kg body weight (BW)] in a completely randomized design for 90 days. Compared to the control group, dry matter intake (DMI, P = 0.02), average daily gain (ADG, P = 0.05), DM (P = 0.0004), organic matter (OM, P = 0.003) and NDF digestibility (P = 0.0005), total VFA (P = 0.02), and plasma total antioxidant capacity (TAC, P = 0.0005) increased when high level of almond (HAL) was added to the diet. Overall, it is revealed that AL had a high nutritional value and could be used up to 23 % of diet DM in the diet of Baluchi male lambs as an inexpensive alternative forage without negative effects on performance and blood metabolites.