Bone mineralisation status of broilers fed reduced-protein diets supplemented with L-arginine, guanidinoacetic acid and L-citrulline

Abstract

<p><b>Context. </b>Mineralisation of the bone matrix is a pivotal factor affecting bone strength in broilers. Reduced bone strength might cause fracture during catching and transportation to slaughterhouses, leading to economic loss. <b>Aims. </b>This study was conducted to investigate the effects of L-arginine (Arg), guanidinoacetic acid (GAA), and L-citrulline (Cit) supplementation to Arg-deficient reduced protein diets on bone mineral composition and mineral digestibility of broiler chickens. <b>Methods. </b>Day-old Ross 308 males were allocated to one of eight dietary treatments with six replicates of 16 birds per treatment. The treatments were standard protein (SP), reduced protein deficient in Arg (RP), and RP with two levels of either Arg (0.238% and 0.476%), GAA (0.309% and 0.618%) or Cit (0.238% and 0.476%). The difference in crude protein content between RP and SP was five percentage points. <b>Key results. </b>Birds fed the RP diet had higher ileal digestibility of P, Na, Mg, S, Al, Fe, Cu and Zn than did those fed the SP on Day 23 (<i>P</i> < 0.01). Supplementation of both Arg, GAA and Cit to the RP reduced Mg digestibility on Day 23 (<i>P</i> < 0.001). The tibia and femur Ca and P concentrations were not different among the dietary treatments on either Day 23 or Day 35 (<i>P</i> > 0.05). Birds fed the RP had lower tibia and femur B concentrations and higher tibia and femur Zn concentrations on Day 23 and Day 35 and higher tibia and femur Mn concentrations on Day 35 than did those fed the SP (<i>P</i> < 0.01). Supplementation of Arg at the high level and Cit at both levels to the RP increased tibia S concentration on Day 23 (<i>P</i> < 0.001). Supplementation of Arg, Cit and GAA to the RP decreased femur Zn concentration on Day 35 (<i>P</i> < 0.001). Supplementation of GAA at the high level decreased concentrations of the tibia and femur B and Fe on Day 23, but increased tibia and femur Mn concentrations on Day 23 and Day 35 (<i>P</i> < 0.01). <b>Conclusions. </b>The findings indicated an increased mineral digestibility but relatively similar bone mineral concentrations in broilers fed the RP diets when compared with the SP diets. <b>Implications. </b>The results of the current study may provide useful information on the bird bone mineralisation and help expand the adoption of reduced-protein diets in the poultry industry.</p>