Evaluation of the effects of environmental temperature and nutrition on growth and development

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Abstract
SUMMARY: Growth and development of young mammals have been investigated in relation to environmental temperature and energy intake. The experimental design and statistical analysis have allowed an evaluation of the separate and combined effects of two environmental variables and the time it takes for these effects to develop. Piglets aged 14 days lived at either 35 or 10 °C, on a high or low energy intake (the energy content of the former was twice that of the latter). The influence of each of the four treatment combinations was assessed up to 64 days of age.At 64 days of age the piglets at 35 °C on the high intake (35H) were twice as heavy as those at 10 °C on the low intake (10L). The other two groups (35L and 10H) had similar body weights, and these were between the 35H and 10L. Ambient temperature had a rapid influence on appearance and morphology: animals in the cold were shorter and squatter than those in the warm. In general, energy intake influenced the absolute size of the internal organs whereas temperature affected their size relative to body weight. Skeletal growth was faster in the warm than the cold, and on the high than the low intake. No statistically significant interactions were generally found between temperature and intake, indicating that their effects were exerted independently. Most of the effects were established after only 17 days.The present investigation has helped in interpreting earlier studies on growth which concentrated on the effects of only one of the two environmental variables of temperature and nutrition. It emphasizes the key roles of nutrition in adaptation to environmental temperature, and of ambient temperature to nutritional studies.