Effect of inclusion of distillers dried grains and solubles from barley, wheat and corn in isonutritive diets on the performance and caecal environment of growing rabbits

<p>To evaluate how the dietary inclusion of distillers dried grains and solubles (DDGS) could affect the performance and caecal environment of growing rabbits, four experimental diets were formulated from a control diet without DDGS (C), including 20% of barley DDGS (Db₂₀), 20% of wheat DDGS (Dw₂₀) and 20 (Dc₂₀) or 40% (Dc₄₀) of corn DDGS. Animals had free access to medicated versions of the diets until 49 d, and then to unmedicated diets until 59 d of age. The performance trial was done using 475 three-way crossbred weaned rabbits of 28 d of age, individually housed in 5 batches. Caecal fermentation traits were determined in 20 animals per diet and at 42 d and at 59 d of age. No significant effect of the growing diet on mortality, morbidity or sanitary risk index was observed. In the whole period and respect to the control group, animals fed with Db₂₀ showed higher dry matter (DM) and digestible energy (DE) intake (+6 and +12%, respectively; P&lt;0.05), but similar daily weight gain (DWG) and increased feed conversion ratio (+9%; P&lt;0.05). Similarly, and regardless of its inclusion level, the increase in DE intake of animals fed with corn DDGS (+9, respectively; P&lt;0.05) did not increase DWG. In contrast, higher DM and DE intake of animals fed with Dw₂₀ (+8; P&lt;0.05) resulted in a higher DWG (+2.8 g/d; P&lt;0.05) than those fed with C. Although inclusion of DDGS at 20% did not affected main caecal parameters controlled at 42 d, caecum of animals fed with the diet Dc₄₀ was characterized by greater N-NH₃ and valeric acid and lower total volatile fatty acids and acetic acid concentrations than the average of the other groups (on av. +5.2±1.7 mmol/L, +0.29±0.07 mol/100 mol, –17.17±4.41 μmol/L and –2.60±0.99 mol/100 mol, respectively; P&lt;0.05). At 59 d of age, higher caecal DM, and propionic and valeric acid concentration and lower values of total volatile fatty acids and acetic/propionic rate were observed for DDGS inclusion at 20% compared to the control (+1.6±0.5%, +0.95±0.44 mol/100 mol, –9.3±4.3 μmol/L and –2.7±1.2, respectively; P&lt;0.05). Linear inclusion of corn DDGS increased caecal DM, propionic acid proportion and total volatile fatty acids concentration and reduced acetate/propionic rate (+4.0±0.4%, +2.27±0.41 mol/100 mol, –21.27±3.9 μmol/L and –5.6±1.1, respectively for Dc₄₀ compared to C; P&lt;0.05). Rabbits given Dc₄₀were also characterized for a greater caecum N-NH3 content than the other groups (on av. –8.7±1.7 mmol/L; P&lt;0.05) at 59 d of age. The results of the present work reveal that inclusion of DDGS up to 20%, independently of the grain source (barley, wheat or corn), could be an interesting alternative in balanced diets for growing rabbits.</p>