2026-09-22T04:01:49Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/116142 2023-07-11 col_2142_5131 col_2142_14771 com_2142_5130 com_2142_685 com_2142_397

Parsons, Carl M Emmert, Jason Koelkebeck, Ken W 2022-08 application/pdf en text Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-11-15 without embargo terms The student, Kersten Bornholt, accepted the attached license on 2022-05-12 at 16:00. The student, Kersten Bornholt, submitted this Thesis for approval on 2022-05-13 at 08:24. This Thesis was approved for publication on 2022-05-23 at 16:34. DSpace SAF Submission Ingestion Package generated from Vireo submission #18027 on 2022-11-15 at 17:37:26 Efficacy of new phytase enzymes for increasing dietary phosphorus utilization by laying hens Bornholt, Kersten 2022-05-23 phytase laying hens phosphorus Three experiments were conducted to determine the efficacy of new phytase enzymes in laying hen diets. The first study focused on corn-expressed phytase (CEP) enzyme in low-nonphytate phosphorus (NPP) diets and whether CEP was a beneficial source of phytase for optimal production in laying hens. Eight diets were fed to 7 replicates of 14 caged laying hens over 24 weeks to observe production performance of hens in two phases: 31 to 48 weeks of age and 49 to 54 weeks of age. Diet 1 consisted of a negative control corn-soybean meal diet containing 0.12% NPP in phase 1 (0-18 weeks) and 0.11% NPP in phase 2 (19-24 weeks). For each phase, Diet 2 was as Diet 1 with 500 FTU/kg of CEP, Diet 3 was as Diet 1 with 3000 FTU/kg of CEP, and Diet 4 was as Diet 1 with 500 FTU/kg of commercially available phytase. Diet 5 was a diet containing 0.30% NPP. Diet 6 was as Diet 5 with 500 FTU/kg of CEP and Diet 7 was as Diet 5 with 3000 FTU/kg of CEP. Diet 8 was a positive control diet containing 0.45% NPP. Hens fed the negative control diet, Diet 1, had reduced (P<0.05) production performance for many measured parameters compared with hens fed the other diets. Performance of hens fed diets supplemented with CEP was not significantly different (P>0.05) than that of hens fed diets supplemented with the commercial phytase or the 0.45% NPP positive control diet. These results indicated that the CEP was efficacious for increasing the utilization of phosphorus (P) by laying hens fed corn-soybean meal diets. Experiments 2 and 3 evaluated a new phytase enzyme for its efficacy to increase P utilization in younger and older laying hens. Experiment 2 included 3 diets consisting of a corn-soybean meal negative control P-deficient diet, or the negative control diet supplemented with 187.5 or 375 FTU/kg of phytase. Each of the 3 diets were fed to 15 replicates of 1 caged hen over the course of 7 days beginning at 30 weeks and 34 weeks of age. Experiment 3 had 3 diets consisting of a negative control P-deficient corn-soybean meal diet containing 0.11% NPP, Diet 2, which was Diet 1 with 150 FTU/kg phytase, and Diet 3, which was a positive control diet containing 0.45% NPP. Each diet was fed to 6 replicates of 14 caged laying hens from 75 weeks of age to 87 weeks of age. Hens in Experiment 2 exhibited no significant differences for production performance among dietary treatments; however, P retention was increased by 187.5 and 375 FTU/kg of phytase. In Experiment 3, hens fed the negative control diet displayed a rapid reduction in feed consumption, egg production, egg mass, and feed efficiency and this treatment was terminated after 5 weeks. There were no significant differences in egg production performance between hens fed the diet with 150 FTU/kg of phytase and hens fed the positive control 0.45% NPP diet. The results of Experiment 2, based on P retention, and Experiment 3, based on egg production performance, clearly indicated that the new phytase enzyme was efficacious for increasing dietary P utilization by laying hens fed corn-soybean meal diets. Thesis eng https://hdl.handle.net/2142/116142 Copyright 2022 Kersten Bornholt M.S. Thesis Animal Sciences University of Illinois at Urbana-Champaign Animal Sciences