Performance and utilization of dietary energy and amino acids in piglets fed low protein diets

Bellego, L. le; Noblet, J.

Livestock Production Science 76(1/2): 45-58


ISSN/ISBN: 0301-6226
DOI: 10.1016/s0301-6226(02)00008-8
Accession: 003878450

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The effect of reducing the dietary crude protein (CP) level on the performance and composition of gain in piglets from 12 to 27 kg, was examined. 32 Pietrain x (Landrace x Large White) barrows were used in the study. Four diets based on corn, wheat, barley, and soyabean meal providing 1.01 g of ileal digestible lysine per MJ of NE (net energy) were prepared. Diet 1 was formulated without free amino acids (AA), whereas in diets 2-4, CP level was progressively reduced and free AA were supplemented according to the ideal protein concept. The CP levels were 224, 204, 184, and 169 g/kg for diets 1, 2, 3, and 4, respectively. Piglets were housed individually and had free access to feed and water. The feed intake was measured daily. At the end of the experiment, animals were slaughtered and body composition was measured. The 12 control piglets were slaughtered at the beginning of the experiment and the composition of gain (water, ash, protein lipid, AA, and energy) was calculated according to the comparative slaughter technique. Feed intake was lowest (P<0.05) with diet 1 (959 g/day) and similar for diets 2-4 (1049 g/day, on average). Nevertheless, average daily gain of the animals did not differ between treatments (666 g/day, on average). Reducing CP level resulted in reduced water consumption and urine production, but had no effect on the occurrence of diarrhoea. The N excretion over the total experiment was reduced by 42% from diet 1 to diet 4. At identical metabolizable energy (ME) intakes (2.52 MJ/day per kg BW0.60), protein and lipid composition of gain (18.9 and 13.0 g/day per kg BW0.60, on average) were not affected by the diet. Energy gain (0.94 MJ/day per kg BW0.60) and heat production (1.58 MJ/day per kg BW0.60) were also not different between treatments. The amino acid pattern of deposited protein was not affected by dietary CP level, except that histidine deposition was significantly smaller with diets 3 and 4. These results indicate that a reduction of dietary CP level by up to 55 g/kg in association with adequate AA supplementation does not affect the level of performance and body composition of piglets and contributes to lower N excretion.