Tibia growth and development in broiler chicks reared under continuous light and melatonin dietary supplementation during the first two weeks of life

Abstract

The first few weeks after broilers hatch are the period of most intense bone growthand development, and the time when they are most susceptible to the in fluence ofvarious external and internal factors. Research in the recent decades has focused on theinvolvement of melatonin in bone development during early life in chickens. Melatoninrelease from the pineal gland has a circadian rhythm, with the highest levels circulatingduring the night and decreasing during the light phase of the day. Various types oflighting are used in intensive broiler production. In this study, the effects of melatoninon the tibial structure and growth of broilers were investigated. During the first twoweeks of life, two groups of chickens were kept under continuous light and fed thesame diet, with the experimental group receiving melatonin in the amount of 0.03 g/kg of feed. The results obtained showed that the addition of melatonin in the diet hadpositive effects on the development and growth of the tibia, which was expressed ina signi ficantly greater thickness of the diaphysis and cortical bone of the diaphysis,higher breaking force and higher values of alkaline phosphatase activity. The corticalbone mineral density of the tibia did not differ signi ficantly between the groups ofchicken.