Auswirkungen von Ernährungs- und Haltungsfaktoren auf die Wärmeproduktion von Ratten und Broilern

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Abstract
In 2 experiments with young broiler chickens, origin Tetra B, heat production was measured in dependence on ambient temperature indirectly and with the gas exchange both over 24 h and in 20-minute periods beginning on their 5th day of life. The chickens, divided into 2 .times. 2 groups according to sex, were constantly kept in a climatic chamber changed in to a respiration chamber during the 8- or 11-week-long experiments. The maximum variation of the temperature was between 5 and 35.degree. C. In the periods of 24-h measurements over 4 days each, the ambient temperature was changed from day to day in steps of 5.degree. C. Heat production was influenced by the age of the chickens, energy intake and ambient temperature. The results of the measurements at the same age and the same energy intake and a temperature variation between 5 and 35.degree. C can well be described by polynomials of the 3rd degree up to the 8th week of life. The thermoregulatory conditioned heat production per 1.degree. C below the critical temperature decreased with the age of the chickens. In the first few weeks of life it was 20 kJ, in the 6th and 7th weeks of life 10-15 kJ and then decreased to 4-5 kJ/kg life weight0.75 .cntdot. d .cntdot. .degree.C. Based on the temperature of minimal heat production, the heat production of 16- to 30-day-old chickens increased to 60-80% at an ambient temperature of 5.degree. C; the metabolism of chickens older than 7 weeks was only increased by about 20%. For the first 2 weeks 35.degree. C were ascertained as critical temperature, for the 3rd to 6th weeks 30.degree. C and for the 7th and 8th weeks 25.degree. C.