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THE NEW NRC: Reviewing the nutrient needs of modern pigs By W H Close, Close Consultancy


Feeding is one of the basic requirements of the animal and represents 60 – 70% of the cost of production. It is therefore important that the nutrient needs of the animal are met under the various conditions in which pigs are kept throughout the world. The latest report of the National Research Committee on ‘The


Nutrient Requirements of Pigs’ is an attempt to provide this information. The report was published in 2012 and is the 11th


such edition. The first


of these nutrient requirements publications was published in 1944 and the tenth in 1998. The objectives of these publications are to review and evaluate the scientific literature on the nutrient requirements of pigs at all stages of production and to make recommendations that can form the basis for the practical feeding of pigs to ensure efficient and environmentally sensitive production practices. During the past decade other reviews have been published, including British Society of Animal Production (2003), Gesellschaft für Ernährungsphysiologie (Germany, 2006), INRA, France (Van Milgen et al. 2008), National Swine Nutrition Guide (USA 2010), Brazilian Tables of Composition of Feedstuffs and Nutritional Requirements (2011) and Danish Nutrient Standards (2012). A major objective of the current NRC report was to review the


nutrient requirements and responses of modern pig genotypes based on new research findings and this has been achieved. Interestingly, compared with previous reviews, this publication has added several new topics to take account of changes in modern pig production. The various chapters are: Energy, Proteins and Amino Acids, Lipids, Carbohydrates, Water,


Minerals, Vitamins, Models for Estimating Nutrient Requirements of Swine, Co-products from the Corn and Soybean Industries, Non-nutritive Feed Additives, Feed Contaminants, Feed Processing, Digestibility of nutrients and energy, Influence of Nutrition on Nutrient Excretion and the Environment, Research Needs, Nutrient Requirements Tables and Tables of Feed Ingredients and Composition. An interesting feature has been the further development of


computer models for the growing and breeding animal, relative to that in the 1998 Review, and the fundamental concepts represented in the models are described. Indeed the models have been used to estimate the energy and amino acid requirements of all classes of pigs, as well as their Ca and P needs. This model is available and may be downloaded from the NRC website. In addition, an extensive review of the published scientific literature


has also been carried out on the nutrient composition of a range of feed ingredients commonly used in pig feeding and the complete analysis of these ingredients has been provided. Thus, compared with previous reviews, the 11th


edition provides information on a range of topics that will help to guide nutritionists and other professionals working in pig PAGE 22 JANUARY/FEBRUARY 2014 FEED COMPOUNDER


ENERGY For the growing-finishing pig the energy requirements are based on the NE system from which the effective ME and DE contents of the diets have been calculated. Equations to calculate NE are adapted from Noblet et al. (1994). His equation was also used to calculate the NE value of feed ingredients in the Feed Composition Tables. The effective ME is then used to calculate the energy and feed needs of the animals to promote different rates of gain at various body weight ranges (5–135 kg) and protein deposition rates (115, 135 and 155 g/day) for pigs of differing sexes (entire and castrated males and females). Information is also provided for entire males immunised against GnRH or fed ractopamine and castrates and gilts also fed ractopamine. For pregnant sows, the requirements are calculated from the body


weight at mating, as well as the anticipated body weight and litter weight gain for animals below and above day 90 of gestation. The requirements are some 18% higher in late compared with early gestation and, for a parity-3 animal with a body weight at mating of 185 kg, are 6.93 Mcal (29.0) ME increasing to 8.18 Mcal (34.2 MJ) ME /day, respectively. For lactating sows, the requirements are based on the post-


farrowing body weight, the anticipated lactation weight loss, as well as the size and daily growth rate of the litter. The requirements of a sow in its first parity are estimated to be 18.7 Mcal (78 MJ) ME per day and for a later parity sow as 20.7 Mcal (87 MJ) ME per day. The requirements for sexually active boars are estimated to be 7.84 Mcal (33 MJ) ME per day.


AMINO ACIDS Amino acids requirements are expressed as either standardised or apparent total tract digestibility. These better define the needs of the animal and take account of the disappearance of amino acids from the hind gut due to microbial fermentation, and which are of no value to the animals per se, as well as endogenous losses. The amino acid requirements are calculated for the same parameters as those for energy. Since there are differences in the profile of amino acid relative to


lysine required for both maintenance and protein gain, the optimum amino acid balance is not constant and therefore varies with the physiological status and level of productivity of the animal. In addition,


nutrition and production to ensure that the nutrient needs of modern pig genotypes are relevant and appropriate. From a nutritional perspective a major interest in the new NRC


publication is the information provided on the energy, amino acids, minerals and vitamin needs of the modern pig and these are briefly discussed.


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