Influence of light on the physiology of turkeys: I. growth

A detailed analysis of publications available clearly suggests, that there are considerable discrepancies relative the influence of light on growth in turkeys. This is largely due to inconsistent experimental design. However, it is safe to state, that both light intensity and light duration exert considerable influence growth in turkeys. Light intensity changes growth i.e. protein accretion and feed efficiency in turkeys via alteration of the endogenous metabolism in general and via energy metabolism in particular. EnglishHowever, recommended levels of light intensity and light duration are variable. For example age and feeding manage ment an but two components responsible. It can be recommended that during growth light intensity should exceed 10 Ix. The recommendation is based on growth rates at different light intensities. Variable light regime show advantages and disadvantages. In general, intermittend and diurnal light schedules result in positive effects on feed efficiency and growth. Continuos illumination is negative in this respect. Step-up light programmes have not shown to be beneficial for growth or feed conversion. The source of light is insignificant relative to growth. Relative to light colour, it is claimed that blue light is beneficial to early growth stages. However, light colour is in close relationship to sensitivity to brightness. Thus blue light effects are rather similar to those observed under low intensity illumination.