EXPOSURE MALE GOAT KIDS FROM SUBTROPICAL REGIONS TO ARTIFICIAL LONG DAYS, STIMULATE A HIGHER GROWTH RATE, BETTER BODY DEVELOPMENT AND INCREASED GLYCEMIA

Background. Small ruminants from subtropical regions are sensitive to respond physiologically to natural photoperiodic changes. In some subtropical goat production systems as located in semi-arid areas of México, the main objective is to obtain in the shortest possible time, males with a suitable weight and body development for sale. Objective. The present study determines if the exposure to artificial long day photoperiod could promote a growth rate, body development and an increased glycemia in male goat kids compared with those under natural short days. Methodology. Starting on late September, 21 creole male goat kids (13 ± 0.1 week aged; mean ± SEM) were assigned to one of the two experimental groups. In the natural short days group, males remain under natural short days from autumn-winter (GDC, n = 10). In the artificial long days group, males were exposed to artificial photoperiod consisting in 16 h light and 8 h darkness (GDL, n = 11). The study lasted until the animals had 35 weeks of age. All animals were fed according their nutritional requirements. Results. During the study, the body weight of the GDL animals was higher than that of the GDCN males (P < 0.05). Due to this, the daily weight gain (GDP) obtained at 23 weeks of age was higher in the GDL males (165 g/day) than that registered in the GDC males (143 g/day; P