Dietary-induced changes of muscle growth rate in pigs: Effects on in vivo and postmortem muscle proteolysis and meat quality1

Abstract

The effects of various growth rates in pigs induced by four different feeding strategies on the activity of the calpain system and on postmortem (PM) muscle proteolysis and tenderness development were studied. An increased growth rate may be caused by an increased protein turnover, which results in up-regulated levels of proteolytic enzymes in vivo that, in turn, possibly will affect PM tenderness development. It can be hypothesized that increased proteolytic activity pre-slaughter will increase the PM tenderization rate. From postnatal d 28 to d 90 (phase 1) the pigs were divided into two groups, given either ad libitum (A) or restricted (R, 60% of ad libitum) access to feed. The two groups were then divided into two subgroups, given either restricted or ad libitum access to feed from d 91 to slaughter at d 165 (phase 2). Measurements of the activity of mu-calpain, m-calpain, and calpastatin; concentrations of total collagen and the percent of soluble collagen; and RNA, DNA, and elongation factor-2 where made at slaugther. Myofibrillar fragmentation index (MFI) was determined at slaughter and 24 h PM. Warner-Braztler shear force was determined 1 d and 4 d PM. Pigs fed restricted diets in phase 1 and fed ad libitum in phase 2 (RA pigs) had increased growth rates in the last phase compared to pigs fed ad libitum during both phase 1 and phase 2 (AA pigs). The increased growth rate (compensatory growth) was followed by an increased proteolytic potential (mu-calpain:calpastatin ratio), increased MFI values, and higher tenderization rates. There was a positive correlation between the activities of m-calpain and growth rates (r = 0.35, P = 0.03), and between RNA levels and growth rates (r = 0.43, P = 0.006). The proposed hypothesis is largely supported by the results. The activities of both mu- and m-calpain at slaughter were highest in fast-growing pigs. The calpain activity was highest in RA pigs, which in turn also had the fastest growth rates prior tslaughter among the four groups. This implies that the synthesis of these enzymes was up-regulated during the second feeding period to a larger extent in RA pigs. The proteolytic potential and the MFI values indicate that the up-regulated in vivo calpain activity had an effect on PM protein degradation, which also is supported by the higher tenderization rate in RA pigs.

Growth performance, carcass characteristics and meat quality of group-penned surgically castrated, immunocastrated (Improvac®) and entire male pigs and individually penned entire male pigs

“…A plausible cause for this difference could be the compensatory growth of IC, compared to C and EMG pigs, at the end of the finishing period. Recently, Kristensen et al (2002) and Bee et al (2006) reported that compensatory growth before slaughter is followed by an increased proteolytic potential (m-calpain : calpastatin ratio) and higher tenderization rate.…”

Meta-analysis of the effect of immunocastration on production performance, reproductive organs and boar taint compounds in pigs

“…Another possible explanation pertains with the much increased growth rate in the weeks before slaughter, resulting in enhanced protein turnover in vivo, and hence increased proteolysis post mortem (Therkildsen et al, 2004;Lametsch et al, 2006). Compensatory growth has been proposed to have a positive effect on pork tenderness (Kristensen et al, 2002).…”

The Performance and Characteristics of Carcass and Breast Meat of Broiler Chickens Fed Diets Containing Flaxseed Meal

“…Kristensen et al (2002) found a relationship between diet and texture of meat. Also, Cisneros et al (1996) and Smith et al (2002) reported a relationship between feed and the colour of meat.…”