Abstract
This study examined the histological properties of Semimembranosus and Triceps brachii muscle in two different bovine breeds, Maremmana (Ma) (an autochthonous breed from Tuscany, Italy) and Limousine (Lm). The animals were grazed in two adjoining pastures, received the same feed supplementation, and were weighed monthly. The experimental period lasted from weaning (6 months old) to slaughter (19 months old). Muscle samples were collected immediately after slaughter, before carcass cooling. Regarding the histological properties, the number of muscle fibers (TNF), mean sarcolemma perimeter (MSP), cross-sectional area, and total sarcolemma perimeter (TSP) were determined. Samples were also analyzed for proximate composition, fatty acid profile of total lipids (TLs), phospholipids (PLs), and neutral lipids (NLs), and for total cholesterol content. Breed was a significant variation factor for the performance parameter and histological muscle fiber properties. Interestingly, despite that Ma being a less extensively genetically improved breed than Lm, it showed higher weight at slaughter (+18%) and daily weight gain (+19%). Ma also showed smaller muscle fibers than Lm and, consequently, the TSP was higher. This difference affected the lipid fraction distribution (Lm was higher in PLs and lower in NLs than Ma) and, consequently, the fatty acid composition of TLs (Lm was high in polyunsaturated fatty acids, while Ma was high in monounsaturated fatty acids). The results of this experiment highlight the importance of environmental and management conditions on the full expression of genotypic potential.
Highlights
Bovine breeds are characterized by a specific phenotypic conformation, which is largely due to the effects of extensive genetic improvement (GI) over the last 50 years
Due to the higher total lipids (TLs) content, Ma was higher in neutral lipids (NLs) and lower in polar lipids than Lm (Table 2)
Muscle significantly affected the carbohydrate and lipid contents, as the former was higher in SM than in Triceps brachii (TB), and the latter was higher in TB than in SM (Table 2)
Summary
Bovine breeds are characterized by a specific phenotypic conformation, which is largely due to the effects of extensive genetic improvement (GI) over the last 50 years. With respect to bovine meat breeds, the goal of GI is to improve animal performance to increase the average daily gain and dressing yield. Some autochthonous bovine breeds, due to their original low productivity, have not been genetically improved, and their current characteristics and phenotypic conformation are quite similar to the original ones. Genetic improvements have affected the animal productivity and the meat quality. Muscle fibers can be histologically and physiologically classified into red-oxidative and white-glycolytic fibers, and, with respect to contraction velocity, into fast twitch and slow twitch [4, 5]. The red-oxidative muscle fibers are smaller than white-glycolytic fibers. Red muscle fibers show a great number of mitochondria, myoglobin, and heme iron [2]
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