Are RFI, Tenderness Connected?
ISU researchers look at how RFI affects pork quality.
Pork producers are also eyeing residual feed intake (RFI) as a means of improving production efficiency and producer profitability. Recently reported research from Iowa State University (ISU) in the Journal of Animal Science may pose a caution to beef producers targeting high-quality beef. An article submitted by S.M. Lonergan (J. Anim. Sci. 2011. 89:192-200) suggests selection for decreased RFI can have corresponding changes in pork quality.
The ISU researchers compared carcasses of pigs from the fifth generation of selection for decreased RFI (select) and a randomly selected line (control). One experiment looked at barrows from control and select lines paired based on age and body weight. Control barrows were heavier at the end of the test period. Calpastatin activity was greater in the longissimus muscle of the select line. Calpastatin is the inhibitor of the calpains, the enzymes that break down muscle for a tenderizing effect.
The second experiment looked at the composition of gilts from control and select lines, with 80 gilts in each group. The select line had 0.043 kg less RFI per day than the control line. Compared two days postmortem, carcasses from the select line tended to have less backfat, greater loin depth, and greater fat-free lean. Loin chops from the select line had less intramuscular lipid content.
The authors note selection for decreased RFI could negatively affect tenderness and texture because of decreased lipid content and decreased postmortem protein degradation.
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