The present study focussed on the energy and protein metabolism in pregnant and lactating goats, including young female goats up to 8 months of age, in order to determine feed availability, as also the energy and protein requirements. It was found that the diets consisting of alfalfa hay, oats hay, maize, wheat bran and mixed feeds (fed to suckling females) had different availabilities in terms of energy and protein, according to animal physiological condition and age. Thus, in pregnant goats, 21% of the metabolizable energy (ME) was used as net energy for pregnancy (foetus plus foetal membranes); the amount of energy required for maintenance was 0.400 MJ/kg 0.75. The availability of digestible protein in the intestines (PDI) for pregnancy was 41.2 +/- 3.1%, while the amount of protein required for maintenance was 2.32 g PDI/kg 0.75. In lactating goats 60.7% of the ME of the diets is used as milk net energy, and 58.9 of the PDI as milk protein. Young female goats had a daily net gain ranging between 173 g and 60 g; the amount of protein in the gain varied between 23 g (month 2) and 12 g (month 8); and that of fat, between 8 g (month 1) and 24 g (month 6). The energy and protein requirements for maintenance were found to be 0.450 MJ ME/kg 0.75 and 2.43 g PDI/kg 0.75, respectively. The net efficiency of ME for growth was of 46.2 +/- 3% and of PDI for protein retention, of 50.1 +/- 2%.

The change of the body composition, of the energy content, and of the energy and protein balances was studied in male and female broiler chicks from hatching to maturity (about 140 days). The animals received corn, soybean meal and fish meal based diets which ensured maximal growth. Correlation were established between the ingested feed and the body evolution both from the point of view of quantity and quality, determining the content of protein, fat, ash, water and energy. By experiments of digestibility and by comparative slaughterings the energy and protein requirements both for maintenance and for protein and fat synthesis were determined.