Effect of inclusion of oat hulls and sugar beet pulp in the diet on productive performance and digestive traits of broilers from 1 to 42 days of age

The effects of the inclusion of additional fibre in the diet on growth performance and digestive traits were studied in broilers from 1 to 42 days of age. There were three diets: a control diet based on rice, soy protein concentrate and fish meal with a crude fibre content of 15 g/kg and two additional diets that included 30 g of either oat hulls (OH) or sugar beet pulp (SBP)/kg. Nitrogen retention and the coefficients of total tract apparent digestibility (CTTAD) of nutrients were determined at 32 days and the relative weight (RW; g/kg body weight) of the gastrointestinal tract and the yield in primal cuts of the carcass were measured at 42 days of age. In addition, growth performance was measured from 1 to 42 days. For the entire experimental period, broilers fed OH had higher (P≤0.01) body weight gain (BWG) and better (P≤0.01) feed to gain ratio (FCR) than broilers fed SBP or the control diet. From 1 to 10 days of age, OH inclusion improved (P≤0.01) BWG and FCR as compared with the control diet. Also, SBP improved FCR in this period but the effects disappeared with age. In fact, from 25 to 42 days of age, SBP inclusion reduced (P≤0.05) feed intake with respect to the control diet and feed intake (P≤0.05) and BWG (P≤0.001) with respect to the OH diet. The RW of the gastrointestinal tract was higher (P≤0.05) with the SBP than with the control diet with the OH diet being intermediate. Also, the RW of the gizzard increased (P≤0.001) with dietary fibre inclusion and the effects were more pronounced (P≤0.05) with OH than with SBP. The digesta content of the gizzard increased (P≤0.001) with fibre inclusion and the effects were more pronounced with SBP than with OH. Leg quarters and breast yields were not affected by dietary treatment. Fibre inclusion increased (P≤0.01) the CTTAD of all nutrients and the metabolisable energy content of the diet. The improvement in CTTAD observed for dry matter and nitrogen was more pronounced (P≤0.01) for OH than for SBP. We conclude that the inclusion of OH in the diet improves growth performance at all ages in broilers fed low fibre diets. Also, SBP inclusion improves growth performance from 1 to 10 days of age but not thereafter. The CTTAD of nutrients were improved by fibre inclusion and the benefits were more pronounced with OH than with SBP.