0
It appears that compensatory growth regimes lead to a range of metabolic adjustments that could potentially affect meat quality. The current experiment was designed to examine if a compensatory feed regime influenced storage of glycogen forms, activity of proteolytic systems and meat quality. Female pigs (Large White x Landrace x Duroc cross) of initial age 74 d were allocated to 6 feeding treatment groups (n = 8 for each group). Groups then consumed feed ad libitum for 40 d (A40), 42 d (A42) or 82 d (A82). The compensatory growth groups were fed 0.70 of ad libitum intake for 40 d (R40) followed by re-feeding for ad libitum intake for 2 d (R40A2) or 42 d (R40A42). Pigs were slaughtered at the end of the restriction period (SL1), then after re-feeding for 2 d (SL2) and 42 d (SL3).
The feeding regime caused restricted animals at SL2 to have a less BW (P = 0.039), with the re-fed animals undergoing compensatory growth by SL3 so BW was not different (P = 0.829). At SL1 there was a trend for the R40 pigs to have less intramuscular fat than A40 (P = 0.084). There was a trend for macroglycogen (MG; P = 0.051) and significant effect for proglycogen (PG; P = 0.014) to be greater at slaughter in R40 than A40, along with a greater postmortem decline in both MG (P = 0.033) and PG (P = 0.022) over the first 2 h in R40, which was associated with the R40 having a lower pH at 24 h postmortem (P = 0.043). After refeeding for 2 d (SL2), only MG of R40A2 was greater (P = 0.030) than A42 and had a trend for a greater difference of decline at 24 h postmortem (P = 0.091), which was associated with lower pH at 24 h (P = 0.012). The data suggest that the levels of PG are more labile and recovered to the levels of pigs fed for ad libitum intake sooner than MG. After full compensation in SL3, there was no difference between glycogen levels and muscle pH. At all slaughter points, there was no difference in shear force. There were no significant effects of the feeding regime on micro- and milli-calpain large subunit gene expression or the activity of the 2 proteolytic enzymes at any of the slaughter dates. In R40 there was a trend (P = 0.070) for greater gene expression of caspase 3, whereas in R40A2 the increase was significant (P = 0.009) relative to pigs consuming feed ad libitum. However, gene expression of the E3 ligase, MuRF1, at SL3 was less in R40A42 (P = 0.019).
In summary, although compensatory growth does appear to influence the expression of various proteolytic systems, the changes do not appear to be associated with meat quality as measured by shear force.
C Chaosap, T Parr and J Wiseman, 2011. Journal of Animal Science, 89(7): 2231-2242. http://dx.doi.org/10.2527/jas.2010-2953