Impact of Dietary Phytogenic Composite Feed Additives on Immune Response, Antioxidant Status, Methane Production, Growth Performance and Nutrient Utilization of Buffalo (<i>Bubalus bubalis</i>) Calves

Abstract

The focus on the bioactive effects of plants concerns mainly ruminal microflora for the modulation of rumen fermentation with very little emphasis placed on their consequences on health parameters, including antioxidative and immune stimulating effects. The aim of the present study was to examine the effects of supplementing phytogenic feed additives composed of a mixture of eucalyptus (Eucalyptus citriodora) and poplar (Populus deltoides) leaf-meal (EPLM) on immune response, antioxidant status, metabolic profile, enteric methane production, growth performance, and nutrient utilization in buffalo (Bubalus bubalis) calves. In vitro studies with graded doses of EPLM extract revealed a reduction in total gas and methane production with an increased proportion of propionate without affecting feed degradability. In the in vivo experimentation, eighteen female buffalo calves (10–14 months old, avg. body weight 131.68 ± 7.50 kg) were divided into three groups (CONT, EPLM-1, and EPLM-2) of six each in a completely randomized design. Treatment groups were supplemented with a blend (1:1) of dry grounded eucalyptus (Eucalyptus citriodora) and poplar (Populus deltoids) leaves (50 g, EPLM-1; 150 g, EPLM-2). Feed intake and growth rate of buffalo calves fed on different feeding regimens did not differ (p > 0.05). Haemato-biochemical parameters reveal no variations (p > 0.05) among groups, irrespective of period of collection, except the concentration of blood urea, which was decreased (p p p p Pasteurella multocida vaccine was higher (p p > 0.05) among the animals. It may be concluded that blends of eucalyptus (Eucalyptus citriodora) and poplar (Populus deltoides) leaf-meal (50 g/h/d) containing 3.19 g, 2.30 g, and 0.71 g of total phenolics, tannin phenolics, and condensed tannins, respectively, can be used as the phytogenic feed additive for improving antioxidant status and immunity of buffalo calves, and mitigating enteric methane production without affecting performance and nutrient utilization.

Keywords

• plant bioactives
• eucalyptus leaves
• poplar leaves
• immune response
• antioxidant status
• nutrient utilization