The effect of addition of Rosemary leaf powder in rooster diet on semen parameters and DNA damage under heat stress

To investigate  the effect of rosemary powder on semen parameters and DNA fragmentation under heat stress, 40 native rooster aged 42 weeksand weighted of 2300 gramswere usedin a factorial experiment in randomized complete block design with two levels of temperature (normal and heat stress) and rosemary powder (0 and 7.5 gr/kg of diet) during 7 weeks. Heat stress and normal temperature was set 28±2ºC and 18-22º C,respectively.After two weeks adaptation,the semen sampleswere collected twice in a week from roosters during 5 weeks using dorso-abdominal massage method. The semen parameters including motility, viability ratio and DNA fragmentation were evaluated. The results showed that heat stress significantly reduced the progressive motility of sperm (type A) and with the addition of rosemary powder, sperm viability increased (P˂0.05). Addition of rosemary leaf powder at normal temperature decreased the DNA fragmentation ratio (P˂0.05). In roosters under heat stress,the DNA fragmentation rate of sperm increased and the damage rate decreased significantly with the feeding of rosemary powder (P˂0.01).  According to the results of this study, adding rosemary powder to the diet of native old roosters under heat stress conditions can improve some reproductive traits