Effects of feeding different levels of dried orange pulp and recycled poultry bedding on the performance of fattening lambs.

The effects of dietary feeding different levels of recycled poultry bedding (RPB) and dried orange pulp (DOP) on the performance of fattening Shal lambs (initial BW of 28 ± 2.2 kg) were assessed using a factorial experiment (2 × 3) with a completely randomized design. Six diets, containing different levels of RPB (0 or 160 g/kg of DM) and DOP (0, 110, or 220 g/kg of DM), were randomly assigned to 6 groups of 6 lambs each for a 74-d period (14 d for adaptation and 60 d for data collection). Diets were offered as total mixed ration to ensure 10% of orts. Feed intake, growth, diet digestibility, microbial nitrogen (N) synthesis (MNS), N retention, rumen fermentation parameters, and blood metabolites were determined. Data were analyzed using the PROC MIXED of SAS. Increasing RPB and DOP levels in the diet of the lambs improved ( < 0.05) DMI, ADG, and G:F. Diet digestibility was not affected by dietary feeding of RPB ( > 0.05), but increased as DOP level increased in the diet ( < 0.05). Feeding RPB and DOP had no effects ( > 0.05) on the ruminal pH. The ruminal total VFA concentration, molar proportion of acetic acid, and acetate-to-propionate ratio increased ( < 0.05) with the increasing dietary levels of RPB and DOP, while ammonia N concentration, propionic acid proportion, total protozoa count, and subfamily number decreased ( < 0.05). Including RPB and DOP in diet enhanced ( < 0.05) MNS and N retention. Feeding RPB-containing diets caused ( < 0.05) an increase of plasma glucose concentration and decreases ( < 0.05) of cholesterol and urea N. As the dietary level of DOP increased, the plasma concentrations of glucose, triglycerides, and urea N reduced ( < 0.05). The plasma antioxidant power was not affected ( > 0.05) by feeding RPB, but increased ( < 0.05) with increasing DOP level in diet. The animal performance reached its greatest value with simultaneous feeding of 160 g of RPB and 220 g of DOP per kg of diet DM. It has been concluded that the partial dietary substitution of RPB (instead of soybean meal, wheat bran, and sugar beet pulp) or/and DOP (instead of barley grain and corn grain) in fattening Shal lambs had positive effects on feed intake, diet digestibility, ruminal microbial N, growth, and N retention. Synchronized feeding of the great levels of RPB (as an N source) and DOP (as an energy source) increased utilization efficiency of these byproducts in the fattening lambs.