Biological performance and gastrointestinal development of broiler chicks fed diets varying in energy : protein ratio

(South African J of Animal Science, 2000, 30, Supplement 1: 136-137

Protease and phytase supplementation of broiler diets in which soybean meal is partially or completely replaced by raw full-fat soybean

The nutrient composition and enzymatic in vitro nutrient digestibility of raw full-fat soybean (RFSB) were assessed prior to evaluating the influences of enzyme supplementation in diets in which commercial soybean meal (SBM) was partially (phase 1) or completely (phase 2) replaced by RFSB. A 2 x 2 + 1 arrangement was used in a two-phase feeding trial. In phase 1 (0 - 25 days) a positive control, commercial-type diet (PC), without RFSB or enzymes, and a negative control diet (NC), with 75 g RFSB/kg were used. The NC diet was supplemented with or without protease (0 or 15000 PRPOT/kg) and phytase (0 or 2000 FYT/kg). In phase 2 (26 - 31 days), RFSB (NC) or SBM (PC) was used as the sole source of crude protein (CP) for birds. Each treatment was replicated six times. Phases 1 and 2 had the same enzyme supplementation and treatment arrangements. The results showed that the concentration of trypsin inhibitors in RFSB as an ingredient was 16 564 TIU/g, and its CP in vitro digestibility was improved significantly by protease and protease plus phytase. Birds fed on PC and on NC plus protease and phytase finally consumed higher quantities of feed and had the highest bodyweight gain (BWG). Protease improved feed intake (FI), BWG and feed conversion ratio (FCR) by approximately 5.3%, 22.5% and 11.4%, respectively, in phase 2. Birds on the diet with protease plus phytase were 11.7% and 24.8% superior in BWG and FCR, respectively, to NC between 26 and 31 days. Supplementation with both enzymes reduced the weight of the pancreas. Supplementing NC with protease and phytase marginally improved the apparent ileal digestibility (AID) of protein and some amino acids (AA) at 25 and 31 days. Overall, BWG and feed efficiency of birds were improved by supplementation of both enzymes and, to a lesser extent, by protease on its own.Keywords: anti-nutritional factors, ileal digestibility, pancreas, trypsin inhibitors, sole source crude protein and amino acid

Performance of broiler chickens fed South African sorghum-based diets with xylanase

Two experiments were conducted to determine the influence of sorghum variety and xylanase on performance of broiler chickens. In Experiment 1A, a total of 240 day-old Ross broiler chickens were assigned to a 2 (sex) × 3 (sorghum variety) × 2 (with or without xylanase) factorial arrangement in a completely randomized design with 20 chickens per treatment. Gross performance measurements were assessed at 7, 14, and 21 days of age. Carcass yield and visceral organ weights were measured at day 21. In Experiment 1B, a total of 108 female Ross 308 broiler chickens were randomly assigned to a 3 (sorghum variety) × 2 (with or without xylanase) factorial arrangement in a completely randomized design with 6 treatments replicated 6 times. On day 25, all birds were euthanazed by intravenous injection of sodium pentobarbitone and digesta contents from the distal ileum were collected to determine the nutrient digestibility. Broiler chickens offered sorghum variety Pan8816 supplemented with xylanase had higher feed intake, weight gain, and similar feed conversion ratio at 1 - 7 days of age. Breast meat of broiler chickens was not affected by variety or xylanase. The small intestine was heavier in the Pan8625 and Pan8816 groups with xylanase than in the similar Pan8906 group. Enzyme inclusion increased the crude protein digestibility. When xylanase was included in all sorghum varieties, numerically, starch digestibility tended to improve. Sorghum variety affected the growth performance of broiler chickens. Furthermore, nutrient digestibility was affected by the differences in variety.Keywords: Digestibility, tannin, poultry, visceral organs, xylanas

Evaluation of fermentation profiles of starches from different plant sources in an in vitro batch culture

The influence of starches containing different levels of resistant starch (RS) on short chain fatty acid formation after fermentation was investigated in an in vitro batch culture. Native starches of sago, sweet potato, potato, arrowroot, rice, wheat, corn, as well as tapioca, cassava pulp and sweet potato root meal were evaluated in buffered caecal inoculum of 28-day old broiler chicks using the cumulative gas production technique. Total starch (TS), resistant starch (RS), short chain fatty acids: acetic, propionic and butyric acids. Short chain fatty acid ratios and fermentation ratios were estimated. Total and resistant starch content of the test starches and their short chain fatty acid profile: acetic, propionic and butyric acids- varied (p<0.05) amongst test starches. There was a strong relationship observed between proportions of acetic, butyric and propionic acids and total short chain fatty acids with R2 values ranging from 0.97 to 0.99, However a weak relationship exist between proportions of acetic, butyric and propionic acids and resistant starch contents of the starches with R2 ranging from 0.19 to 0.22, highlighting that variations in short chain fatty acid profiles of the fermented starches investigated in vitro was due to plant source rather than RS content of the test starches.Keywords: Native starch; Resistant starch; Short chain fatty acids; Fermentation ratios; Caecal inoculu