Effect on digestion and performance of dietary protein content and of increased substitution of lucerne hay with soya-bean protein concentrate in starter diets for young rabbits

Abstract

The aim of this work was to study the effect of protein source / availability on the intestinal microbiota, digestive traits and nutritional performance of early-weaned rabbits. The effects of supplemental antibiotics in the drinking water were also evaluated. Four isoenergetic and isofibrous diets were formulated: a control diet with a high protein (207 g/kg dry matter (DM)) and lucerne hay content (HPHL), a diet with low crude protein (CP) (179 g/kg DM) and high lucerne hay content (LPHL) and low protein diets in which the lucerne hay in diet LPHL was replaced partially (LPML) or totally (LPLL) with soya-bean protein concentrate. Rabbits, weaned at 25 days (52 per diet), were fed the experimental diets for a 2-week period and thereafter received a commercial diet until 56 days of age. The incidence of mortality was investigated using 70 animals per diet without supplemental medication. The profile of the ileal microbiota was studied at 35 days of age in rabbits treated (18 per diet) or not (12 per diet) with antibiotic. As expected, supplementation with antibiotics effectively reduced fattening mortality rate and microbial biodiversity. However, lowering of also the dietary CP content led to a reduction in the mortality rate ( P , 0.05), both in animals treated with (by 80%) or without (by 39%) antibiotics. In addition, there was a reduction ( P , 0.05) in the frequency of Clostridium perfringens in nonmedicated animals. Neither jejunal morphology nor growth performance, over the whole fattening period, was affected by dietary CP content of the experimental diets. However, with HPHL, feed efficiency was higher (by 4.8%; P , 0.01) than with LPHL diets. Substitution of lucerne hay with soya-bean meal in low protein diets did not affect apparent faecal or ileal digestibility of DM and CP. However, the ileal digestibility of cystine, alanine, aspartic acid, and proline was lowered ( P , 0.05) with increasing substitution by soya bean. Nevertheless, ileal CP flow, incidence of mortality and presence of C. perfringens were unaffected. Our results suggest that a reduction in dietary CP, resulting in reduced lumenal flows of nitrogen through the ileum, may be beneficial for young rabbits and limit the numbers of potentially harmful bacteria in the lower gut. Modulation of dietary CP should be contemplated as a strategy to increase the intestinal health in rabbits.

Effect of decreasing dietary protein level and replacing starch with soluble fibre on digestive physiology and performance of growing rabbits

“…seem to gain an advantage from protein unbalance and in particular from its excess. In fact, reducing protein level and increasing ileal protein digestibility significantly decreased mortality caused by epizootic rabbit enteropathy (Xiccato et al, 2006;Chamorro et al, 2007) and reduced the presence of Clostridium perfringens and total anaerobic bacteria at ileum in growing rabbits (García-Palomares et al, 2006). Feugier et al (2006), however, did not find differences in the health status of rabbits when reducing dietary CP from 210 to 150 g/kg.…”

New trends in rabbit feeding: influence of nutrition on intestinal health. A review

“…Easily hydrolysable milk proteins are replaced primarily with less digestible plant proteins, as animal proteins are mostly banned from animal feeds. The level and source of plant protein included in starter diets also have an influence on intestinal disorders, as a decrease of dietary protein content or an increase in ileal protein digestibility (sunflower meal vs soybean meal or potato protein concentrate) reduced the flow of protein towards the fermentative area and decreased the mortality due to ERE incidence (Gutiérrez et al, 2003;García-Ruiz et al, 2006;Chamorro et al, 2007c;see Fig. 3).…”

Effect of dietary soluble fibre level and protein source on growth, digestion, caecal activity and health of fattening rabbits

“…Contrary to the findings of studies on pigs (Vente-Spreeuwenberg et al, 2004a, b), in our assay the protein source did not affect intestinal mucosa traits. Similarly, Chamorro et al (2007) the contrary, mucosa integrity was improved in early-weaned rabbits fed diets containing animal plasma rather than soybean (Gutiérrez et al, 2000) and possible damage to mucosa depending on feeding legume anti-nutritional factors has been hypothesised (Gutiérrez et al, 2003;Cano et al, 2004).…”

“…As occurs with protein excess, the use of less digestible protein sources may increase the nitrogen flux at caecum and favour the development of pathogenic strains of E. coli and Clostridium spp., thus impairing animal health and performance (Gutiérrez et al, 2003;García-Ruiz et al, 2006;Chamorro et al, 2007).…”