Protein and amino acid levels and sequence in swine diets: effects on gain, feed conversion, and carcass characteristics

Pierce, A.B.; Bowland, J.P.

Canadian Journal of Animal Science 52(3): 531-541


ISSN/ISBN: 0008-3984
DOI: 10.4141/cjas72-064
Accession: 000172561

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At 5 weeks of age 176 pigs were divided into groups in 2 experiments and given diets containing 20, 17 or 14% protein or 14% protein with 0.2% L-lysine hydrochloride only or with 0.1% DL-methionine also. Each experiment was in 3 periods, the starting period to 6 weeks after division into groups, the growing period from 6 to 12 weeks and the finishing period from 12 weeks to slaughter. The pigs were slaughtered after reaching 86 kg. Pigs given 14% protein throughout had the lowest average daily feed intake, and took on average 2 to 3 weeks longer to reach slaughter weight. Extra lysine increased feed intake in the growing and finishing periods and overall, but not in the starting period. Lysine and methionine were no better than lysine alone. Feed intake, average daily gain and feed conversion were less when low-protein diets were given in the starting period, but as the pigs grew older a compensatory effect developed so that feed intake, average daily gain and especially feed conversion efficiency were greater with the low-protein and amino acid-supplemented diets than with the higher-protein diets. Feed intake and rate of gain were greater for castrated males than for females, but feed conversion was the same and females gave better carcasses. Digestibilities of energy and N were not significantly influenced by protein level, sex or breed. In one experiment, loin area of carcass was less in pigs given 14% protein, and amino acids increased it. Landrace X Yorkshire pigs gained faster than Hampshire X Yorkshire but gave poorer carcasses.