Research note: Effects of L-carnitine and L-arginine on sperm quality and fertility potential of aged broiler breeder roosters

This objective of this study was to investigate the effects of L-arginine (L-Arg) and L-carnitine (LC) and their mixture in the diet (at lower levels) on sperm quality in aging broiler breeder roosters. Thirty-two broiler breeder roosters of the Arian breed were kept at 50 wk of age after a 12-wk acclimatization period. The birds were divided into four treatments and eight replicates in a completely randomized design. Treatments included (1) control (CON), 2) diet supplemented with 150 mg LC per kg diet, (3) diet supplemented with 500 mg L-Arg per kg diet, and (4) diet supplemented with 75 mg LC + 250 mg L-Arg. The use of LC in the roosters' diet increased the concentration, percentages of total mobility, progressive motility, curvilinear velocity and straight line velocity compared to the CON and L-Arg treatment (P < 0.05). The percentage of apoptosis was lower in the LC, L-Arg + LC and L-Arg groups than in the CON group (P < 0.05). In general, LC and the mixture of LC and L-Arg probably improve the sperm quality of aged cockerels through the supply of adenosine triphosphate, antioxidant effects, and the synthesis of nitric oxide.