Thermal manipulation during embryogenesis improves certain semen parameters in layer breeder chicken during hot climatic conditions

Thermal manipulation during incubation has been shown to improve post hatch performance in poultry. The aim of the present experiment was to evaluate thermal manipulation on semen quality of roosters during hot climatic conditions. Eggs obtained after artificial insemination from Dahlem Red layer breeders were randomly divided into two groups control (C) and heat exposed (HE). C group eggs were incubated at 37.5 °C throughout the incubation period while the HE group eggs were exposed to higher temperature 40.5 °C from 15th to 17th day of incubation for 3 h each day. The relative humidity was maintained at 65% in both the groups throughout incubation. The chicks hatched were reared separately under standard husbandry conditions. During high ambient temperature semen from roosters (45 weeks of age) was collected and evaluated for different gross parameters, sperm chromatin integrity and sperm HSP27 and HSP70 gene expression by real-time PCR. The seminal plasma was evaluated for lipid peroxidation, ferric ion reducing antioxidant power (FRAP), triiodothyronine (T3) and matrix metalloproteinase-2 (MMP-2) activity. The shed average Temperature Humidity Index (THI) during the experiment period was 78.55. The percent live sperm and FRAP level were significantly (P < 0.05) higher and sperm gene expressions were significantly (P < 0.05) lower in the HE group. No differences in other parameters were observed between the groups. Thus from the results it could be concluded that thermal manipulation during incubation improves certain semen parameters of roosters at high ambient temperature.