Changes in the histochemical properties and meat quality traits of porcine muscles during the growing-finishing period as affected by feed restriction, slaughter age, or slaughter weight1

Abstract

In this study, the degree of contractile and metabolic development of myofibers in porcine LM, rectus femoris (RF), and dark and light portions of the semitendinosus (STD and STL, respectively) was determined, and their impact on meat quality was compared at the same age but different BW (trial 1) or at a given BW but different age (trial 2) in 48 Swiss Large White barrows from 12 litters after the growing and finishing period. The barrows had ad libitum (A) or restricted (R, 80% of A) feed access. In trial 1, at 113 and 154 d of age, 6 barrows in treatment A (62.1 and 99.5 kg of BW, respectively) and 6 siblings in treatment R (51.0 and 86.6 kg of BW, respectively) were slaughtered. In trial 2, a similar protocol was used except that the barrows were slaughtered at 61.3 (104 or 119 d of age, respectively) or 101.3 kg of BW (145 or 167 d of age, respectively). Muscle fibers were stained and classified as slow oxidative (SO), fast oxidative-glycolytic (FOG), or fast glycolytic (FG), and fiber area and distribution were determined. At 113 and 154 d of age, R barrows had smaller (P < or = 0.04) SO fibers in the LM, STD, and STL, smaller (P < 0.01) FOG fibers in the STL, smaller (P = 0.03) FG fibers in the LM, and smaller (P < or = 0.04) overall mean area in the LM, STD, and STL. In the STL and RF, R barrows had fewer (P < or = 0.06) FG and more (P < or = 0.08) FOG fibers than A barrows at 113 and 154 d of age. Except for smaller FOG fibers in the STD of R compared with A barrows slaughtered at the same BW, the myofiber size did not differ (P > or = 0.11). However, the LM tended to have fewer (P = 0.06) SO and more (P < 0.01) FG fibers, and the STD had more (P < 0.01) FOG fibers in R barrows. Regardless of whether R barrows were slaughtered at the same age or the same BW as the A barrows, shear force values and cooking losses were greater (P < or = 0.08) in the STD and STL of R barrows. These findings revealed that myofiber hypertrophy was impaired by feed restriction in barrows compared at the same age, but differences in myofiber size vanished at the same BW. By contrast, restricted nutrient supply affected myofiber maturation depending on the age and BW, but the impact differed between muscles. The absence of changes in myofiber type distribution among the younger-lighter and older-heavier barrows indicated that myofiber maturation was already completed in the younger-lighter barrows. Although changes in meat quality traits were affected by the feeding regimen, they were not related to myofiber characteristics.

Influence of production system in local and conventional pig breeds on stress indicators at slaughter, muscle and meat traits and pork eating quality

“…In agreement with our results, reduced meat lightness and water loss have been observed in outdoor pigs by Pugliese et al (2005), whereas Bee et al (2004) reported lower meat lightness but higher drip in outdoor v. indoor pigs. Despite higher pH1 and pHu and lower drip, which have all been positively associated with mechanical tenderness of pork (Huff-Lonergan et al, 2002;Bee et al, 2007), BE pigs had higher meat shear force values than BC pigs. This cannot be ascribed to the amount or solubility of LM collagen, which did not differ between groups, but may be related to the trend (P = 0.11) for lower IMF in BE pigs, in agreement with the welldescribed negative relationship between IMF content and shear force of pork, especially for IMF values above 2.5% (De Vol et al, 1988;Lebret, 2009).…”

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

“…By contrast, allometric growth coefficients of muscles involved with posture, such as the LM, are higher. Thus, they may be regarded as developmentally retarded muscles (Bee et al, 2007). As the second vaccination reduces the anabolic potential in the late finishing period, LM development might be more affected than ham and shoulder.…”

“…Both samples were then cooked on a grill plate (Beer Grill AG, Zurich, Switzerland) at 190 to 1958C, to an internal temperature of 698C, and cooking losses were measured. Using a Warner-Bratzler shear device (Model 3000, G-R Electric Mfg Co., Manhattan, KS, USA), shear force was measured as described earlier (Bee et al, 2007). From each carcass, adipose tissue samples (both layers) were collected at the 10 to 14th-rib level, vacuum-packaged and stored at 2208C until further analysis.…”

“…In addition, the fatty acid profile in the adipose tissue was determined as described earlier (Bee et al, 2007).…”

Performances, meat quality and boar taint of castrates and entire male pigs fed a standard and a raw potato starch-enriched diet

“…Using a Warner-Bratzler shear device (Model 3000; G-R Electric Mfg. Co., Manhattan, KS, USA), shear force values were determined as previously described (Bee et al, 2007). In addition, adipose tissue (both layers) was sampled at the 10th to 13th rib level, vacuum-packed and stored at 2208C until further analysis.…”