The effect of dietary nutrient density on growth in the pig

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Abstract
SUMMARY: Forty-eight Large White ♂× (Landrace × Large White) ♀ male castrate pigs were individually fed, on a live-weight-based scale between approximately 23 kg and 88 kg live weight, similar daily in-takes of digestible energy, crude protein and total lysine from four diets (12 pigs per diet) of widely differing compositions and nutrient densities. The digestible energy contents (MJ/kg) (1), crude protein (%) (2) and total lysine (%) (3) contents of the diets were: diet A (1) 11·40, (2) 14·40, (3) 0·82; diet B (1) 12·90, (2) 16·50, (3) 0·94; diet C (1) 14·96, (2) 19·20, (3) 1·09 and diet D (1) 18·28, (2) 23·30, (3) 1·32. To give the required daily nutrient intakes, relative to diet A (100) the intakes of diets B, C and D were 87·5, 75·0 and 62·5 respectively. Growth rates, carcass weights (from dissimilar but non-significantly different slaughter weights), killing-out percentages and the digestible energy required to produce a unit of carcass improved progressively from diet A to diet D. In these variables the significant differences tended to lie between diets A and B on the one hand compared with diets C and D on the other. The weights of lean tissue dissected from the carcass were similar for all pigs. The weights of dissected fatty tissue and backfat thicknesses increased from diet B to C to D but only the differences between diets B and D were statistically significant.