Efficiency of the utilization of the energy of food in laying hens

Abstract

SUMMARYThe efficiency of utilization of the energy of food in White Leghorn laying hens for egg production was measured. A ration with a gross energy of 4469 kcal/kg dry matter and 19·4% crude protein had a metabolizable energy of 80·1±1·7% of the gross energy, and 78·5±5·3% of the metabolizable energy was present as net energy.The maintenance requirement of metabolizable energy of White Leghorn hens weighing 1·723±48·5 kg and a production of 19·3±0–49 eggs per month was 125·8 kcal/kg0·75/24 hr.The energy cost per g of protein and fat synthesized by laying White Leghorn hens was estimated to be 7·20 and 12·13 kcal metabolizable energy respectively.

An energy response curve for a commercial white leghorn laying‐strain cross

“…compares with values of 507 to 560 kj ME/Wkg 0>75 reported by Waring and Brown (1967), Burlacu andBaltac (1971), O'Neill andJackson (1974) and Farrell (1975), and 415 kj ME/W°-75 (Grimbergen, 1970) for White Leghorn hens adjusted to the same temperature.…”

“…The regression of energy balance on ME intake in studies reported by Waring and Brown (1967), Burlacu and Baltac (1971) and Farrell (1975) yielded values of 79% to 86% for the efficiency of utilization of ME for maintenance and production of White Leghorn hens. In all cases linear regression was appropriate, indicating similar efficiencies above and below maintenance.…”

“…In the calorimetric studies of Waring and Brown (1967), Burlacu and Baltac (1971) and Farrell (1975), birds were subjected to restricted feed intakes for 3 to 5 d before measuring heat production over a similar period. In contrast, we fitted the response model to data obtained 12 to 16 weeks after imposing restricted feeding.…”

“…Multiple linear regression equations partitioning the metabolizable energy (ME) consumed by laying hens between maintenance, egg production and changes in body energy content have been developed from calorimetric experiments such as those of Brown (1965,1967), Grimbergen (1970), Tasaki and Sasa (1970), van Es et al (1970), Burlacu and Baltac (1971) and Farrell (1975). Estimates of the daily ME requirements for egg production derived from calorimetric studies are often lower, by 15% to 25%, than the ME consumed on average by laying hens fed ad libitum (Grimbergen, 1974;Agricultural Research Council, 1975).…”

Modelos para estimar as exigências de energia metabolizável para poedeiras

“…As exigências energéticas para produção de ovos variam de 1,92 (Sakomura, 1989) a 3,15 (Combs, 1968) e as eficiências, de 61,0% a 83,7% (Santomá, 1991). Sakomura et al (1993a), ao elaborarem equação de predição das exigências energéticas para poedeiras leves, consideraram eficiência de conversão da energia da dieta para produção de ovos de 80%, que foi estabelecida de acordo com o proposto por Waring & Brown (1965), Grimbergen (1970), Burlacu & Baltac (1971) e NRC (1984. Porém, os resultados deste experimento (62%), assim como os descritos por Coon & Zhang (1999), de 63%, podem indicar que a eficiência energética sugerida pelos trabalhos pioneiros pode estar superestimada, ocasionando subestimativa das exigências energéticas para produção de ovos.…”