Histochemical properties of fibre types in muscles of wild and domestic pigs and the effect of growth rate on muscle fibre properties

Abstract

This study reports the results of a comparison of the histochemical properties of various types of porcine muscles in wild and domestic pigs. In domestic pigs, the influence of growth rates on these properties were studied in five muscles: longissimus dorsi (LD), semimembranosus (SM), gluteus superficialis (GS), infra spinam (IS) and masseter (MAS). The growth rate was expressed as (i) live weight (LW) at 165 ± 2d and (ii) daily LW gain from day 88 to day 165 (DG) on the experimental diet.LD, SM, GS and IS of wild pigs were found to contain a higher area percentage of oxidative type IIA fibres (type IIA% area ) and a lower percentage area of glycolytic type IIB fibres (type IIB% area ) than the same muscles of domestic pigs. The capillary density in the light muscles (LD, SM, GS) of wild pigs was twice that of domestic pigs, indicating higher oxidative capacity. In domestic pigs the cross sectional area of type IIB fibres (CSA IIB ) was markedly larger than the cross sectional area of type I (CSA I ) and IIA (CSA IIA ) fibres. The average fibre cross sectional area (CSA fibre ) was about the same in the muscles of wild and domestic pigs except in LD and SM, where the average fibre cross sectional area was approximately 25% smaller in wild pigs than in domestic pigs. This difference was caused by 1 the large cross sectional area of type IIB fibres in the light muscles of domestic pigs.In the light muscles of domestic pigs, the cross sectional area of type IIA fibres increased most with increasing growth rate. Growth rate influences muscle fibre properties only in light muscles, not in dark muscles.

New Insights into Muscle Fibre Types in Casertana Pig

“…Our study shows that the psoas minor muscle contains more capillaries per fibre and per mm 2 than the rhomboideus and longissimus dorsi. The smaller fibre area of the muscle also resulted in higher capillary density as confirmed by Ruusunen et al (2004).…”

Carbohydrate metabolism in meat animals

“…It is also generally accepted that, within the muscle tissue, some lactate may be transported via the interstitial fluid from white, glycolytic, fibres to red fibres (type 1 and IIA) which have higher mitochondrial density. It can be speculated that in domestic pigs this phenomenon is of minor importance, because the percentage of red fibres is small in muscles such as M. longissimus, gluteus and semimembranosus (Ruusunen 1994;Karlström, 1995;Ruusunen & Puolanne 2004). …”

“…The size of the heart in beef cattle has been reported to be approximately 0.44% of live weight (Sainz & Bentley, 1997) and in pigs 0.33% (Ruusunen & Puolanne, unpublished), and even greater difference is seen in the capillary density. In the longissimus muscle of cattle the capillary density is approximately 450/mm 2 (Karlström, Essén-Gustavsson, & Lindholm, 1994), but in pigs the value is only 150/mm 2 (Ruusunen & Puolanne, 2004). It is generally accepted that the blood flow into skeletal muscle at rest is about 20% of cardiac output, but it may increase to up to 80% of cardiac output during intense exercise.…”

A comparative study on the expression profile of MCTs and HSPs in Ghungroo and Large White Yorkshire breeds of pigs during different seasons

“…The oxidative capacity of the domesticated pig is low (Essen-Gustavsson 1986;Karlsson 1993;Ruusunen 1994), and the muscles contain mainly thick fast glycolytic fibers (IIB), which in stressful situations easily switch their energy metabolism to anaerobic glycolysis. Generally, lactate formed in glycolytic (white) muscle fibers is transported to the liver or to oxidative (red) fibers to be used as a fuel.…”