Evaluating a novel consensus bacterial 6-phytase variant on growth performance of broilers fed U.S. commercial diets deficient in nutrients and energy through 63 days of age

Abstract

An experiment was conducted to evaluate the efficacy of a novel consensus bacterial 6-phytase variant expressed in Trichoderma reesei (PhyG) in broilers fed corn-soybean meal-based diets with application of dose-specific full nutrient and energy matrix values. Ross 708, straight-run broilers (n = 2,016) were assigned to one of 7 dietary treatments, with 12 replicate pens/diet and 24 birds/pen. Diets were a nutrient adequate control (PC), nutrient reduced negative controls 1, 2, and 3 (NC1, NC2, and NC3) with reductions in available phosphorus (avP) by 0.15%, 0.18%, and 0.19%, calcium (Ca) by 0.17%, 0.20%, and 0.21%, dig amino acids (AA) by 0.02-0.05%, sodium (Na) by 0.03-0.05%, and metabolizable energy (ME) by 62.8, 68.8, and 69.5 kcal/kg, respectively. Other diets were the NC1, NC2, and NC3 respectively supplemented with 500 (PhyG500), 1,000 (PhyG1000), and 2,000 (PhyG2000) FTU/kg. Over the 63-day feeding period, decreasing nutrient specifications lowered body weights (P<0.05) in broilers from 4,518g in PC to 4,256 g and 4,191 g and increased body weight-corrected feed conversion ratio (FCR, P<0.05) from 1.92 in PC to 2.06 and 2.08 in the NC2 and NC3, respectively. Compared with PC, PhyG maintained (P>0.05) BW in broilers fed PhyG500 (4,474 g), PhyG1000 (4,417 g) and PhyG2000 (4,449 g). Moreover, PhyG at all dose-levels maintained (P>0.05) overall FCR vs. PC. The NC1, NC2, and NC3 diets decreased (P<0.05) tibia ash vs. PC, and eachPhyG500, PhyG1000, and PhyG2000 completely restored tibia ash to the similar levels (P>0.05) as the PC. Carcass yield was decreased (P<0.05) by NC1 (80.63%), NC2 (80.51%), and NC3 (80.31%) vs. PC (81.96%) with complete alleviation by PhyG500 (82.11%), PhyG1000 (81.80%), and PhyG2000 (81.54%). In conclusion, the novel consensus phytase variant completely compensated for the reduction in dietary avP, Ca, dig AA, and ME at each dose-level and maintained growth performance, bone quality, carcass characteristics, and nutrient digestibility in a typical corn-soybean mean based diet fed to broilers through 63 days of age.

Effects of a Novel Consensus Bacterial 6-Phytase Variant on Growth Performance and Bone Ash of Broilers Fed Complex Diets Highly Deficient in Minerals, Digestible Amino Acids and Energy through 42 Days of Age

“…Body weight and feed intake (FI) were measured on day 0, 10, 21, 35, and 42, on a per-pen basis, and used to calculate average daily gain (ADG), average daily feed intake (ADFI), and mortality-corrected feed conversion ratio (FCR). On day 21 and 42, 6 birds per pen (3 males and 3 females) had both tibias collected, and the tibia ash was analyzed [ 19 ]. Ileal digesta were collected from the euthanized birds on day 21 and analyzed for apparent ileal digestibility (AID) [ 19 ].…”

“…On day 21 and 42, 6 birds per pen (3 males and 3 females) had both tibias collected, and the tibia ash was analyzed [ 19 ]. Ileal digesta were collected from the euthanized birds on day 21 and analyzed for apparent ileal digestibility (AID) [ 19 ]. On day 42, 5 birds per pen (3 males and 2 females) were weighed then euthanized by exsanguination and carcass component yields were measured using certified standard commercial processing procedures.…”

“…Titanium dioxide concentration in feed and ileal digesta was analyzed using a modified protocol [21]. Following the procedures presented in Sobotik et al [19] and described in brief here, dried samples were weighed and placed in an ashing oven at 450 • C. Samples were then titrated with sulfuric acid and boiled until dissolved and then further titrated with hydrogen peroxide and water. Finally, samples were analyzed for absorption using a spectrophotometer.…”