Physical and Semen Characteristics of Mexican Creole Roosters in Summer and Autumn, at 19° North Latitude with a Constant Photoperiod

ABSTRACT The objective of this study was to evaluate the effect of the seasons (Summer and Autumn), on live weight, body condition, mass motility, percentage of live spermatozoa, and sperm-cell concentration of Creole roosters (Gallus domesticus) from Mexico. Semen from 35-week-old Creole roosters was collected weekly during 10 weeks in Summer and Autumn, through the dorso-abdominal massage technique. Roosters were individually kept under a constant photoperiod (16 hours light:8 hours dark). The average live weight was 4.5% higher (p<0.05) in Autumn (2.78 kg) than in Summer (2.66 kg), therefore this variable increased with age (r = 0.85, p<0.05). Category 2 of body condition occurred (p<0.05) with higher probability than the others (0, 1 and 3), being practically the same (p>0.05) in Autumn (99.96%) and in Summer (99.81%). On average (and in weeks 1 and 3-10), the percentage of live spermatozoa was higher in Summer than in Autumn. Accordingly, the percentage of live spermatozoa decreased with age (r = -0.82, p<0.05). However, on average, sperm-cell concentration did not change between seasons (p>0.05). In conclusion, Mexican Creole roosters showed higher percentage of live spermatozoa in Summer than in Autumn. Therefore, it is advisable to select these animals of about 2.7 kg and reproduce them in Summer.