The ranked importance of dietary factors influencing the performance of broiler chickens offered phytase-supplemented diets by the Plackett-Burman screening design

ABSTRACT

1.The objective of the present study was to rank the importance of the following dietary factors; canola meal, wheat, whole barley, digestible lysine, phytate-P, calcium, available P, sodium and three NSP-degrading feed enzymes. Their influence on growth performance, gastro-intestinal tract parameters, energy utilisation, ileal N digestibility and disappearance rates were determined via the Plackett-Burman design in broiler chickens offered phytase-supplemented diets.

2. The eleven dietary factors were assigned two levels in the Plackett-Burman design matrix. The resulting twelve dietary treatments were offered to six replicates per treatment (six birds per cage) with a total of 468 male Ross 308 broiler chicks from 7 to 28 d post-hatch.

3. Increasing digestible lysine levels improved weight gain by 15.6% (P < 0.001) and gain:feed by 9.36% (P < 0.001). Increasing calcium levels reduced weight gain by 6.36% (P < 0.001) and gain:feed by 2.60% (P < 0.001). The high calcium level increased gizzard pH from 2.78 to 3.01 (P < 0.005). Whole barley significantly increased relative gizzard weights and contents, pancreas weights and both ileal N digestibility coefficients (0.774 versus 0.803; P < 0.001) and ileal N disappearance rates (23. 3 versus 24.5 g/bird/day; P < 0.001).

4. Overall, digestible lysine level and calcium level were identified as the most influential dietary factors to influence growth performance of broilers offered phytase-supplemented diets, which hold implications for practical diet formulations.

KEYWORDS:

• Broiler
• performance
• phytase
• Plackett-Burman
• screening design

Acknowledgments

The authors would like to acknowledge the financial support and guidance of Danisco Animal Nutrition for Ms Amy Moss’ PhD candidature. We would also like to thank Ms Joy Gill and her team at the Poultry Research Foundation at The University of Sydney Camden Campus for their practical assistance and support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Danisco Animal Nutrition, Dupont.