The efficacy of manganese in improving semen quality of heat-stressed male layer chickens

ABSTRACT The reproductive efficiency of breeder roosters is crucial due to the low male-to-female ratio, particularly under heat stress, which negatively impacts fertility. This study evaluated the effects of dietary manganese supplementation on semen quality and reproductive hormones in 45 Hi-Line breeder roosters (50 weeks old) over a 12-week period at the College of Agriculture, Al-Qasim Green University, Iraq. Roosters were assigned to five groups (three replicates per group, three birds per replicate) and fed either a control diet (basal diet, T5) or diets supplemented with 10, 20, 30, or 40 mg of manganese sulfate per kg of feed (T1–T4). Semen samples were analyzed biweekly for ejaculate volume, sperm motility, concentration, and plasma membrane integrity. Blood samples were collected to assess testosterone, LH, FSH, and oxidative stress markers (ALT, AST, GPx). Results showed significant differences (P ≤ 0.05) among treatments. The control (T5) had the highest ejaculate volume, while T4 and T5 improved sperm motility. T3 and T5 increased sperm concentration, whereas T1 and T2 reduced the percentage of dead and abnormal sperm. These findings suggest that manganese supplementation enhances reproductive performance under heat stress