The influence of phytase, pre-pellet cracked maize and dietary crude protein level on broiler performance via response surface methodology

Amy F Moss; Peter V Chrystal; Yueming Dersjant-Li; Peter H Selle; Sonia Yun Liu

doi:10.1186/s40104-019-0385-y

The influence of phytase, pre-pellet cracked maize and dietary crude protein level on broiler performance via response surface methodology

J Anim Sci Biotechnol. 2019 Oct 4:10:80. doi: 10.1186/s40104-019-0385-y. eCollection 2019.

Authors

Amy F Moss^{1

2}, Peter V Chrystal^{1

3

4}, Yueming Dersjant-Li⁵, Peter H Selle¹, Sonia Yun Liu^{1

3}

Affiliations

¹ 1Poultry Research Foundation within The University of Sydney, 425 Werombi Road, Camden, NSW 2570 Australia.
² 2School of Environmental and Rural Science, University of New England, Armidale, NSW 2351 Australia.
³ 3School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney, NSW 2006 Australia.
⁴ Baiada Poultry Pty Limited, Pendle Hill, NSW Australia.
⁵ Danisco Animal Nutrition, DuPont Industrial Biosciences, Marlborough, UK.

Abstract

Background: The reduction of crude protein levels in diets for broiler chickens may generate economic, environmental and flock welfare and health benefits; however, performance is usually compromised. Whole grain feeding and phytase may improve the utilization of reduced crude protein diets.

Results: The effects of pre-pellet cracked maize (0, 15% and 30%) and phytase (0, 750 and 1500 FTU/kg) in iso-energetic maize-soy diets with three levels of crude protein (22%, 19.5% and 17%) were evaluated via a Box-Behnken response surface design. Each of 13 dietary treatments were offered to 6 replicate cages (6 birds/cage) of male Ross 308 broiler chicks from 7 to 28 d post-hatch. Model prediction and response surface plots were generated from experimental data via polynomial regression in R and only significant coefficients were included and discussed in the predicted models. Weight gain, feed intake and FCR were all influenced by pre-pellet cracked maize, phytase and crude protein level, where crude protein level had the greatest influence. Consequently, the reduction from 22% to 17% dietary crude protein in non-supplemented diets reduced weight gain, feed intake, relative gizzard weight, relative gizzard content and relative pancreas weight but improved FCR. However, the inclusion of 30% cracked maize to 17% crude protein diets restored gizzard weight and 1500 FTU phytase inclusion to 17% crude protein diets increased relative gizzard contents and pancreas weights. Cracked maize and phytase inclusion in tandem to 17% crude protein diets increased weight gain, feed intake and FCR; however, this FCR was still more efficient than broilers offered the non-supplemented 22% crude protein diet. Broilers offered the pre-pellet cracked maize and phytase inclusions reduced AME in 22% crude protein diets but improved AME by 2.92 MJ (14.16 versus 11.24 MJ; P < 0.001) in diets containing 17% crude protein. Ileal N digestibility was greater in broilers offered diets with 17% crude protein than those offered the 22% crude protein diet; irrespective of phytase and pre-pellet cracked maize.

Conclusion: Pre-pellet cracked maize and phytase inclusions will improve the performance of broilers offered reduced crude protein diets.

Keywords: Crude protein; Maize; Phytase; Pre-pellet whole grain; Response surface.