Efficiency of Energy and Nutrient Use in the Production of Edible Protein of Animal Origin

Flachowsky, G. 2002. Efficiency of energy and nutrient use in the production of edible protein of animal origin. J. Appl. Anim. Res., 22: 1–24. The production of edible protein of animal origin as the principal objective of livestock husbandry served as the basis for the nutritional and ecological calculations undertaken here. The nutritional parameters calculated were the amount of gross energy and crude protein required per kg of dietary protein from milk, beef, pork, poultry meat, rabbit meat and eggs. The competition for food between farm animals and humans was assessed by determining the amount of concentrate required per kg of edible protein. Emissions of N, P and methane per kg of dietary protein formed the basis for ecological considerations. The results of nutritional and ecological calculations for different livestock species and categories are determined primarily by yields. As yields increase the proportion of the maintenance requirement allocated to the product or unit of edible protein becomes relatively smaller; this reduces the amount of energy and protein required and increases their conversion efficiency. At daily yields of 30 kg milk, 1000 g gains in beef catte, 700 g in pigs, 40 g in broilers and a laying performance of 80%, the production of 1 kg edible protein from milk, beef, pork, poultry meat or eggs requires a gross energy of about 0.4; 1.2; 0.6; 0.25 and 0.35 GJ, respectively and 3.4, 9.0, 6.0, 3.0 and 3.5 kg of crude protein, respectively. N emissions per kg of edible protein for the five protein sources amount to about 0.35, 1.2, 0.8, 0.3 and 0.4 kg; calculated P emissions were about 50, 180, 120, 40 and 60 g, respectively. At the stated yield levels, protein production from milk, poultry meat or eggs is, therefore, more efficient both nutritionally and ecologically than that from pork and beef. Competition for food with humans is greater in the production of protein from non-ruminants (pigs, poultry) than ruminants; this parameter is also dependent on the proportion of by-products from agriculture and food production in the daily ration and on the animals' yields. The global aim of a sustainable and ecologically acceptable production of protein of animal origin can be achieved by reducing livestock herds, increasing animal performance and utilising feedingstuffs in animal nutrition that are unsuitable for direct consumption by human beings.