The influence of dietary crude protein concentrations, grain types and arginine:lysine ratios on the performance of broiler chickens

Shemil P Macelline; Peter V Chrystal; Chanon Inanan; Mehdi Toghyani; Peter H Selle; Sonia Yun Liu

doi:10.1016/j.aninu.2023.05.007

The influence of dietary crude protein concentrations, grain types and arginine:lysine ratios on the performance of broiler chickens

Anim Nutr. 2023 May 26:14:259-268. doi: 10.1016/j.aninu.2023.05.007. eCollection 2023 Sep.

Authors

Shemil P Macelline^{1

2}, Peter V Chrystal^{1

2

3}, Chanon Inanan¹, Mehdi Toghyani^{1

2}, Peter H Selle^{2

4}, Sonia Yun Liu^{1

2}

Affiliations

¹ School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Camperdown, 2006, NSW, Australia.
² Poultry Research Foundation within The University of Sydne, Camden, 2570, NSW, Australia.
³ Complete Feed Solutions, Howick, 2145, New Zealand.
⁴ Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, 2570, NSW, Australia.

Abstract

The objective of this study was to investigate the effects of dietary crude protein (CP) concentrations, grain types and arginine:lysine ratios on performance parameters of broiler chickens. The 2 × 2 × 2 factorial array of dietary treatments harnessed two CP concentrations (210 and 170 g/kg), two feed grains (wheat and sorghum), and two arginine:lysine ratios (104 and 110). Each dietary treatment was offered to 7 replicates of 14 birds per floor pen, a total of 784 off-sex male, Ross 308 broilers, from 14 to 35 d post-hatch. The dietary CP reduction compromised weight gain by 10.0% (2078 versus 2310 g/bird) as a main effect and FCR by 7.51% (1.474 versus 1.371), subject to an interaction. In a three-way interaction (P = 0.008), expanded arginine:lysine ratios improved FCR by 2.30% in 170 g/kg CP, sorghum-based diets but compromised FCR by 2.12% in corresponding wheat-based diets. Sorghum was the more suitable feed grain in reduced-CP diets as sorghum generated significant advantages in weight gain of 7.59% (2154 versus 2002 g/kg) and FCR of 6.94% (1.421 versus 1.527) in birds offered 170 g/kg CP diets. Both dietary CP and feed grain generated significant and divergent impacts in apparent ileal digestibility coefficients for the majority of 16 assessed amino acids. Dietary CP reductions increased non-bound amino acid inclusions (NBAA) in wheat-based diets (48.96 versus 9.80 g/kg) to a greater extent than sorghum-based diets (35.3 versus 9.50 g/kg) and increasing dietary NBAA inclusions were linearly associated with compromised weight gain (r = -0.834; P < 0.001) and FCR (r = 0.862; P < 0.001). Increasing ratios of free arginine to lysine plasma concentrations were linearly (r = -0.466; P = 0.004) related to improvements in FCR. The implications of the observed outcomes are discussed and possible explanations are advanced.

Keywords: Amino acid; Broiler chickens; Energy; Protein; Sorghum; Wheat.