Effect of extruding the cereal and/or the legume protein supplement of a compound feed on in vitro ruminal nutrient digestion and nitrogen metabolism

Abstract

An experiment was performed to evaluate the effect of extruding the cereal and/or the protein supplement of a compound feed for intensively reared calves on ruminal N metabolism using an in vitro culture system. A conventional compound feed was produced without extruding [treatment non-extruded (NE)], with the cereal blend extruded (CE), with the protein blend extruded (PE) and with both cereal and protein blends extruded (CPE). Four experimental diets, consisted of 0.90 of each experimental compound feed and 0.10 barley straw were assessed using dual-flow continuous-culture fermenters. (15)N infusion as ammonia sulphate was used to label the microbial population. Average NH(3) concentration in fermenter effluents ranged from 270 mg/l with diet NE to 69 mg/l for diet CPE (p < 0.05) and volatile fatty acid concentrations ranged from 161 mm in diet PE to 130 mm in diet CPE (p < 0.05). Diets PE and CPE showed a lower true organic matter degradability (49.5% and 48.2%) than NE and CE (52.8% and 52.2%). Non-ammonia nitrogen flow in effluents was highest on diet CPE, intermediate on diets CE and PE and lowest on diet NE (p < 0.01), reflecting the differences in dietary N flow and dietary protein degradability (71.2%, 63.7%, 61.2% and 50.0%, respectively, for NE, CE, PE, CPE; p < 0.001). In contrast, microbial protein synthesis efficiency was lower for treatments including the cereal blend extruded, although the resulted differences were only significant (p < 0.001) for CPE diet.

Effects of cereals and/or protein supplement extrusion on diet utilisation and performance of intensively reared cattle

“…The extrusion of both the cereal and protein blend (treatment CPE) caused a reduction in total tract NDF apparent digestibility in agreement with the results obtained with the same diets in continuous cultures (Solanas et al, 2007), and in vivo with intensively reared calves fed the extruded or non-extruded concentrate (Solanas et al, 2005b). In the latter case, the lower digestibility was associated with a sub-clinic acidosis due to rapid carbohydrate fermentation but this was not the case in the in vitro assay, where a constant pH (6.4) was maintained throughout the incubation period.…”

“…Nevertheless, in these studies heat treatments were performed at higher temperatures than in the present study, and several authors have found a higher proportion of ruminal undegraded protein as temperature heat treatment increases (Cros et al, 1991;Petit et al, 2002). However, Solanas et al (2007) obtained higher differences in crude protein degradability than those found in this experiment when the same diets (PE and NE) were incubated in continuous culture fermenters (0.612 vs. 0.712, S.E. = 0.0127).…”

“…Although several works have revealed that this is closely related to the microbial flow (Perez et al, 1997;Martín-Orúe et al, 2000), an important amount, up to the 40%, of purine bases reaching the duodenum of calves fed concentrate diets does not seem to be of microbial origin (Vicente et al, 2004b) and this proportion may depend on diet characteristics (Askar et al, 2005). However, in continuous culture fermenters and using N 15 as microbial marker, Solanas et al (2007) also found a lower N bacterial flow and efficiency of microbial protein synthesis with CPE compared with NE, CE and PE diets.…”

The Effect of Glandless Cottonseed Meal Content and Process Parameters on the Functional Properties of Snacks during Extrusion Cooking

“…Proximate chemical compositions of the optimal treatment as well as two commercial corn-based snacks were determined in triplicate according to AOAC methods [27]. Crude fiber was measured by acid-alkaline digestion [28]. Nitrogen free extract (NFE) was calculated as the percentage difference of the sum of protein, fiber, fat and ash content.…”