Genotype with nutrition interactions for carcass composition and meat quality in pig genotypes selected for components of efficient lean growth rate


Animal Science (1999) 69 : 69-80

Genotype with nutrition interactions in carcass composition and meat quality traits were examined by testing animals from four selection lines and a control line on isoenergetic diets, which differed in lysine : energy content. The selected lines resulted from seven generations of selection for high daily food intake, lean food conversion ratio (LFC) and lean growth rate on ad-libitum or restricted (LGS) feeding regimes in a Large White population. There were 128 animals in the study, with 24 animals per selection line and 32 pigs from a control line. During performance test, 30-90 kg, animals were fed one of three isoenergetic diets, 14.0 MJ DE/kg DM, which differed in ileal digestible lysine : digestible energy (A : 0.40, C : 0.76 and E : 1.12 g lysine/MJ DE) on ad-libitum or restricted (0.75 g/g ad-libitum daily food intake) feeding regimes.

For the majority of performance test, carcass composition and meat quality traits there was no evidence of a genotype with diet or genotype with feeding regime interaction. The selection line with feeding regime interactions for average daily gain, daily food intake and rates of lean and subcutaneous fat deposition were primarily due to the feeding regime effect on the LFC selection line. Selection for high LFC had reduced ad-libitum daily food intake to such an extent that it was not significantly different from daily food intake on a restricted feeding regime, unlike other selection lines in the study. A selection line with feeding regime interaction was detected for muscle pH24 hr. and muscle reflectance, which resulted from the LGS selection line. Ad-libitum fed LGS animals had higher muscle pH24 hr. and lower muscle reflectance than restricted fed LGS animals, while there was no effect of feeding regime for the other selection lines.

The general absence of genotype with nutrition interactions for traits measured in the study indicated that the ranking of genotypes for performance test traits, carcass composition and meat quality traits will not be dependent on diet or feeding regime. Genotype specific nutritional inputs will also not be required for identification of animals of high genetic merit, within a genotype. However, diet and feeding regime had significant effects on carcass composition and meat quality traits, such that the estimated mean value of a genotype will be dependent on the diet or feeding regime used to evaluate the genotype.

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