Abstract
Selective breeding and improved nutritional management over the past 20-30 years has resulted in dramatic improvements in growth efficiency for pigs and poultry, particularly lean tissue growth. However, this has been achieved using high-quality feed ingredients, such as wheat and soya that are also used for human consumption and more recently biofuels production. Ruminants on the other hand are less efficient, but are normally fed poorer quality ingredients that cannot be digested by human subjects, such as grass or silage. The challenges therefore are to: (i) maintain the current efficiency of growth of pigs and poultry, but using more ingredients not needed to feed the increasing human population or for the production of biofuels; (ii) improve the efficiency of growth in ruminants; (iii) at the same time produce animal products (meat, milk and eggs) of equal or improved quality. This review will describe the use of: (a) enzyme additives for animal feeds, to improve feed digestibility; (b) known growth promoting agents, such as growth hormone, β-agonists and anabolic steroids, currently banned in the European Union but used in other parts of the world; (c) recent transcriptomic studies into molecular mechanisms for improved growth efficiency via low residual feed intake. In doing so, the use of genetic manipulation in animals will also be discussed.
Highlights
Selective breeding and improved nutritional management over the past 20–30 years has resulted in dramatic improvements in growth efficiency for pigs and poultry, lean tissue growth
Feed ingredients account for a large proportion of the overall costs of animal production, in nonruminant species[4]
Recent molecular studies are starting to identify other mechanisms that might be utilised in the future, including manipulation of gut microflora or gut peptides and targeting of gene expression in skeletal muscle or other tissues using drugs or genetic manipulation (GM) technologies
Summary
Selective breeding and improved nutritional management over the past 20–30 years has resulted in dramatic improvements in growth efficiency for pigs and poultry, lean tissue growth This has been achieved using high-quality feed ingredients, such as wheat and soya that are used for human consumption and more recently biofuels production. The challenges are to: (i) maintain the current efficiency of growth of pigs and poultry, but using more ingredients not needed to feed the increasing human population or for the production of biofuels; (ii) improve the efficiency of growth in ruminants; (iii) at the same time produce animal products (meat, milk and eggs) of equal or improved quality. Over the past 50 years, tremendous advances in animal genetics and animal nutrition have been made to meet the increasing demand, in pigs and poultry, but this has mainly been achieved using highquality feed ingredients such as wheat, maize and soya. This review will highlight a few ways in which this is being achieved or might be achieved in the future
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