| Abstrakt: |
The capacity of a novel consensus bacterial 6-phytase variant (PhyG) to maintain growth performance and production benefits of pigs when added to an energy and nutrient-reduced mixed cereal diet was assessed. Two experiments were conducted. In Exp. 1 (wean to finish), weaned pigs [n = 192; initial body weight (BW) 7.18 ± 0.38 kg] were randomized to 4 treatments from weaning until market weight. Diets were provided in 5 phases. Treatments included: 1) a nutritionally sufficient positive control (PC); 2) a negative control (NC1) without added inorganic phosphate, reduced (based on specific PhyG dose) in net energy (NE), calcium (Ca), digestible amino acids (AA) and sodium (Na) vs. PC, supplemented with PhyG at 1,000, 1,000, 750, 500 and 500 FTU/kg in each phase, respectively (NC1+low PhyG); 3) a negative control (NC2) as NC1 supplemented with PhyG at 2,000, 2,000, 1,000, 750 and 750 FTU/kg in each phase and further reduced in energy and nutrient based on specific PhyG dose (NC2+high PhyG), and; 4) a negative control (NC3) as 2) and supplemented with xylanase–β- glucanase (XB) to provide 2,400 U/kg xylanase and 304 U/kg β-glucanase, with additional reduction in NE and digestible AA based on the contribution of XB (NC3+low PhyG + XB). In Exp. 2 (nursery), weaned pigs (n = 360; initial BW 8.40 ± 0.78 kg) were assigned to 3 dietary treatments from weaning up to 35 d. Diets were offered in 2 phases. Treatments included a nutritionally adequate positive control (PC) and 2 PhyGsupplemented diets, reduced in digestible phosphorus, Ca, Na, NE and digestible AA vs. PC, according to the expected contribution of PhyG added at 1,000 FTU/kg (NC1) or 2,000 FTU/kg (NC2), respectively. Data were analyzed by ANOVA. Means separation was by Tukey’s HSD test. In Exp. 1, overall growth performance (114 d) in all enzyme-supplemented diets was maintained or improved compared with PC. Compared with PC, feed cost per kg BW gain was significantly reduced by 7.3% and total carbon footprint (CFP; CO2 eq. g/ kg BW gain) was reduced by 6.8% with PhyG + XB combination. In Exp.2, overall growth performance (35 d), in all PhyG-supplemented, nutrient-reduced, treatments, were either not different from, or were improved, vs. PC. Total feed costs and estimated CFP per kg BW gain were reduced in all PhyG-supplemented, nutrient- and NE-reduced treatments vs. PC. In conclusion, the application of a full energy and nutrient matrix maintained the overall growth of pigs in both 114- and 35-d studies with the novel phytase. The addition of XB further improved the overall growth of market pigs. Moreover, full matrix application with PhyG achieved reductions in total feed cost and carbon footprint in both studies. [ABSTRACT FROM AUTHOR] |
