www.IndianJournals.com Members Copy, Not for Commercial Sale Downloaded From IP - 117.218.111.52 on dated 16-Aug-2017 Indian Journal of Poultry Science (2016) 51(3): 350-352; Short Communication DOI: 10.5958/0974-8180.2016.00066.0 Effect of in ovo thermal manipulation on rooster semen quality during hot climatic condition M. SHANMUGAM*, A. VINOTH, K.S. RAJARAVINDRA AND U. RAJKUMAR ICAR-Directorate of Poultry Research, Rajendranagar, Hyderabad 500 030, India (Received on December 05, 2016; accepted for publication on December 31, 2016) ABSTRACT Shanmugam, M., Vinoth, A., Rajaravindra, K.S. and Rajkumar, U. 2016. Effect of in ovo thermal manipulation on rooster semen quality during hot climatic condition. 51(3): 350-351. Thermal manipulation during embryogenesis improves adaptation to heat stress in adult chicken. The aim of the present study was to evaluate the effect of higher temperature during incubation on rooster semen quality during hot climatic condition. Male chicks hatched from normal incubation temperature (37.5°C and 65% relative humidity; Control-C) and higher incubation temperature (39.5°C and 65% relative humidity; heat exposed-HE) provided between 16-18 th day of incubation for 3 hours each day were reared and evaluated for semen quality during high ambient temperature (Temperature Humidity Index (THI)-80.94). At 64 weeks of age semen from eight roosters from each group was collected and evaluated for different gross semen parameters, hypo-osmotic swelling test, sperm chromatin damage and seminal plasma cortisol. The results showed no significant difference between the groups in any of the parameters studied except for abnormal sperm that were lower in the HE birds. It was concluded that higher temperature during incubation reduced abnormal sperm percent during heat stress. However further research on duration and time of heat treatment during incubation is needed to bring overall improvement in rooster semen quality during heat stress. Key words: Hot climate, rooster, semen, sperm DNA damage, thermal manipulation, *Corresponding Author: Email: dr_shan@rediffmail.com Ambient temperature is an important factor that affects the semen quality of roosters. The semen parameters are adversely affected during summer or on exposure to high ambient temperature (Joshi et al., 1980; McDaniel et al., 1996). In laboratory animals mild scrotal heat stress for shorter duration causes DNA damage in the developing sperm (Banks et al., 2005). Thermal manipulation during embryogenesis appears to improve the thermo tolerance in poultry. This is based on the hypothesis that thermal manipulation during critical periods causes epigenetic adaptation mechanisms and adapts the birds for the expected post natal environmental conditions (Tzschentke and Halle, 2009). Beneficial effects of thermal manipulation during broiler chick embryogenesis on thermo tolerance acquisition (Yahav, 2009) and post natal body weight (Tzschentke and Halle, 2009) have been reported. However, studies on thermal manipulation during embryogenesis to induce epigenetic heat adaptation of roosters in terms of semen quality are not available. Therefore the objective of this study was to evaluate the effect of thermal manipulation during incubation on rooster semen quality during natural hot climatic conditions. The experiment was carried out at the experimental poultry farm of Project Directorate on Poultry, Hyderabad, India. Four hundred and sixty eggs obtained from Dahlem Red breeder line were randomly divided into two groups (Control-228; Heat exposed -232). Control (C) group was maintained at 37.5°C and 65% relative humidity throughout the incubation period; heat exposed (HE) group eggs were exposed to higher temperature 39.5°C from 16-18 th day of incubation for 3 hours each day with relative humidity maintained at 65%. The heat exposure of eggs was done in a separate incubator and kept back in the incubator with normal temperature on all the three days of exposure. A total 367 chicks (190 C and 177 HE) were obtained after hatching of eggs. The chicks were reared in battery brooders and from 18 weeks of age the roosters were housed in individual breeder cages in an open-sided elevated house under natural photoperiod and climatic conditions. The birds had free access to both feed and water. The roosters were trained for semen collection from 21 weeks of age and semen was periodically removed from the birds. At 64 weeks of age eight roosters from each group were randomly selected for semen evaluation during peak summer. The mean ambient temperature (Ta) 32.22°C and relative humidity (RH) 48.92% in the shed during the week of the experiment was used to calculate the THI, according to the formula: THI = (0.8×Ta) + [(RH/100)×Ta–14.3)]+46.4) (Mader et al., 2010). The average THI during the week of semen evaluation was 80.94. The trial was conducted following the approval of the Institute Animal Ethics Committee. Semen from roosters was collected by abdominal massage (Burrows and Quinn, 1937), diluted immediately four times using high temperature (HT) diluent (Chaudhuri and Lake, 1988) and used for laboratory evaluation. The semen volume was assessed by using 1 ml syringe. Sperm motility was subjectively assessed as percentage of progressively motile sperm by placing a drop of the diluted