Effect of dietary replacement of alfalfa with urea-treated almond hulls on intake, growth, digestibility, microbial nitrogen, nitrogen retention, ruminal fermentation, and blood parameters in fattening lambs.

Abstract

The objective of this study was to assess the effect of dietary replacement of alfalfa with urea-treated almond hulls (UAH) on DM and nutrients intakes, growth performance, diet digestibility, microbial N supply (MNS), N retention, rumen fermentation parameters, and blood metabolites in fattening male Shall lambs (29.9 ± 1.9 kg initial BW). Three diets, with equal ME and CP concentrations and a forage-to-concentrate ratio of 40 to 60, were formulated in which alfalfa was replaced by different levels (0, 200, or 400 g/kg of diet DM) of UAH. Experimental diets were randomly assigned to the 3 groups ( = 8/group) in a completely randomized design for a 74-d period (14 d for adaptation and 60 d for data collection). Diets were offered as a total mixed ration to ensure 10% orts. Dry matter and nutrients intakes, animal growth, diet digestibility, MNS, N retention, rumen fermentation parameters, and plasma metabolites were determined. The dietary substitution of UAH for alfalfa had no effects on DMI (linear, = 0.96; quadratic, = 0.86), ADG (linear, = 0.35; quadratic, = 0.19), and G:F (linear, = 0.66; quadratic, = 0.13). In vivo digestibility coefficients of DM (linear, = 0.82; quadratic, = 0.42), OM (linear, = 0.73; quadratic, = 0.95), CP (linear, = 0.24; quadratic, = 0.66), and ash-free NDF (linear, = 0.69; quadratic, = 0.74) were not affected by the dietary treatment. Feeding lambs on diets containing UAH instead of alfalfa had no effects on MNS (linear, = 0.63; quadratic, = 0.68) and N retention (linear, = 0.44; quadratic, = 0.17). Rumen pH (linear, = 0.26; quadratic, = 0.071), ammonia N (linear, = 0.39; quadratic, = 0.13), and VFA (linear, = 0.091; quadratic, = 0.86) concentrations, acetic acid-to-propionic acid ratio (linear, = 0.93; quadratic, = 0.62), and protozoa population (linear, = 0.62; quadratic, = 0.22) were not influenced by the experimental diets. Substituting alfalfa with UAH had no effects on the plasma concentrations of glucose (linear, = 0.55; quadratic, = 0.91), triglycerides (linear, = 0.97; quadratic, = 0.44), cholesterol (linear, = 0.71; quadratic, = 0.70), urea N (linear, = 0.084; quadratic, = 0.12), total protein (linear, = 0.53; quadratic, = 0.96), albumin (linear, = 0.43; quadratic, = 0.39), and globulin (linear, = 0.39; quadratic, = 0.25). It is concluded that UAH can be fed to fattening Shall lambs as a total replacement (400 g/kg of diet DM) for alfalfa without negative effects on animal performance. This byproduct can be a safe feedstuff to use in sheep diets and could help to reduce environmental pollution.