Effects of L-arginine, guanidinoacetic acid and L-citrulline supplementation in reduced-protein diets on bone morphology and mineralization of laying hens

Hiep Thi Dao; Amy F Moss; Emma J Bradbury; Robert A Swick

doi:10.1016/j.aninu.2023.03.012

Effects of L-arginine, guanidinoacetic acid and L-citrulline supplementation in reduced-protein diets on bone morphology and mineralization of laying hens

Anim Nutr. 2023 Jun 16:14:225-234. doi: 10.1016/j.aninu.2023.03.012. eCollection 2023 Sep.

Authors

Hiep Thi Dao^{1

2}, Amy F Moss¹, Emma J Bradbury³, Robert A Swick¹

Affiliations

¹ School of Environmental and Rural Science, Faculty of Science, Agriculture, Business and Law, University of New England, Armidale, New South Wales, 2351, Australia.
² Faculty of Animal Science, Vietnam National University of Agriculture, Trau Quy Town, Gia Lam District, Hanoi, 100000, Vietnam.
³ Baiada Poultry Pty Limited, Pendle Hill, New South Wales, 2145, Australia.

Abstract

The alterations in feed ingredients and the nutrient matrix to produce reduced-protein diets may affect bone morphology and mineralization in laying hens. This study was implemented to determine the effects of L-arginine (Arg), guanidinoacetic acid (GAA), and L-citrulline (Cit) supplementation to Arg-deficient reduced-protein diets on bone morphology, strength, and mineralization status of laying hens. Individually housed Hy-Line Brown laying hens were evenly distributed to five dietary treatments with 25 replicates per treatment from 20 to 40 wk of age. Treatments consisted of a standard protein diet (17% crude protein, SP), a reduced-protein diet deficient in Arg (13% crude protein, RP), and RP supplemented with Arg (0.35% Arg, RP-Arg), GAA (0.46% GAA equivalent to 0.35% Arg, RP-GAA), or Cit (0.35% Cit equivalent to 0.35% Arg, RP-Cit) to reach the Arg level of SP diets. Birds fed the SP diet had similar bone weight, ash, length, width, Seedor index, breaking strength, and serum mineral concentration, but higher toe B level (P < 0.001) compared to those fed the RP diet at wk 40. Birds fed the SP diet consumed more but also excreted more K and B compared to those fed the RP diet (P < 0.01). Birds fed the SP diet had lower Cu digestibility (P = 0.01) and higher B retention (P < 0.01) compared to those offered the RP diet. Supplementation of Arg, GAA, and Cit to the RP diet increased relative femur weight and length (P < 0.001). Citrulline supplementation also increased relative tibia and femur ash, and Zn digestibility (P < 0.05). Supplementation of GAA to the RP diet decreased serum Ca, P, and Mg levels, decreased tibia Fe and Mg levels and toe Mg level, but increased Al, Fe, Zn, and Mn digestibility (P < 0.05). The current findings demonstrated the capacity of laying hens to adapt to low mineral intake by increasing mineral utilization. Overall, bone morphology and breaking strength, and serum mineral level in laying hens were not influenced by dietary CP levels. Dietary Arg, GAA, or Cit supplementation were effective in improving bone morphology and mineralization in laying hens fed Arg-deficient RP diets.

Keywords: Ash; Breaking strength; Digestibility; Femur; Low protein; Minerals.