Collagen content and architecture of thepectoralismuscle in male chicks and broilers reared under various nutritional conditions

Concentration of collagen fibers in the musculature of broiler chickens fed with cupuacu seed by-product

ABSTRACT In this essay, we quantify the concentration of collagen fibers in broiler chickens exposed to increasing concentrations of cupuacu seed by-product. Collection of material was carried out in five chickens per treatment at 70 days old in the groups: control, 5% and 10% inclusion of cupuacu seed by-product. Fragments of Thoracic Pectoralis (PT) and Iliotibial lateralis (ITL) muscles were prepared for light and electronic microscopy. The amount of collagen fibers in the muscle groups was 1.08±0.61% in the PTC group; 6.24±2.58% in PT5% and 7.30±2.75% in PT10%. In the Iliotibial Lateralis groups, the results were 6.96±3.14% in the ITLC; 7.43±4.22% in the ITL5% and 8.66±2.35% in ITL10%. The amount of collagen fibers in the ITL5% and ITL10% groups showed no significant statistical difference. However, when compared to the ILTC group, there was a significant statistical difference. The PT muscle responds to standard nutritional changes, unlike the ILT muscle, which requires a high-nutrient formulation. The use of 5% cupuacu seed by-product has proven to be a viable alternative source of animal feed, as it promotes an increase in the concentrations of collagen fibers in the musculature of broiler chickens and is possibly the determining factor in meat texture.

Impact of divergent selection for ultimate pH of pectoralis major muscle on biochemical, histological, and sensorial attributes of broiler meat

The impact of divergent selection based on the ultimate pH (pHu) of pectoralis major (P. major) muscle on the chemical, biochemical, and histological profiles of the muscle and sensorial quality of meat was investigated in broiler chickens. The protein, lipid, DM, glycogen and lactate content, glycolytic potential, proteolysis, lipid and protein oxidation index, muscle fiber cross-sectional area, capillary density, and collagen surface were determined on the breast P. major muscle of 6-wk-old broilers issued from the high-pHu (pHu+) and low-pHu (pHu-) lines. Sensory attributes were also evaluated on the breast (roasted or grilled) and thigh (roasted) meat of the 2 lines. Protein, lipid, and DM content of P. major muscle were not affected by selection ( > 0.05). However, the P. major muscle of the pHu+ line was characterized by lower residual glycogen (-16%; ≤ 0.001) and lactate (-14%; ≤ 0.001) content and lower glycolytic potential (-14%; ≤ 0.001) compared with the pHu- line. Although the average cross-sectional area of muscle fibers and surface occupied by collagen were similar ( > 0.05) in both lines, fewer capillaries per fiber (-15%; ≤ 0.05) were observed in the pHu+ line. The pHu+ line was also characterized by lower lipid oxidation (thiobarbituric acid reactive substance index: -23%; ≤ 0.05) but protein oxidation and proteolysis index were not different ( > 0.05) between the 2 lines. At the sensory level, selection on breast muscle pHu mainly affected the texture of grilled and roast breast meat, which was judged significantly more tender ( ≤ 0.001) in the pHu+ line, and the acid taste, which was less pronounced in the roasted breast meat of the pHu+ line ( ≤ 0.002). This study highlighted that selection based on pHu does not affect the chemical composition and structure of breast meat. However, by modifying muscle blood supply and glycogen turnover, it affects meat acidity and oxidant status, both of which are likely to contribute to the large differences in texture observed between the 2 lines.

Oral ingestion of collagen peptide causes change in width of the perimysium of the chicken iliotibialis lateralis muscle

Skeletal muscle is mainly composed of myofibers and intramuscular connective tissue. Bundles composed of many myofibers, with each myofiber sheathed in connective tissue called the endomysium, are packed in the perimysium, which occupies the vast bulk of the intramuscular connective tissue. The perimysium is a major determination factor for muscle texture. Some studies have reported that collagen peptide (Col-Pep) ingestion improves the connective tissue architecture, such as the tendon and dermis. The present study evaluated the effects of Col-Pep ingestion on the chicken iliotibialis lateralis (ITL) muscle. Chicks were allocated to three groups: the 0.15% or 0.3% Col-Pep groups and a control group. Col-Pep was administered by mixing in with commercial food. On day 49, the ITL muscles were analyzed by morphological observation and the textural property test. The width of the perimysium in the 0.3% Col-Pep group was significantly larger than other two groups. Although scanning electron microscopic observations did not reveal any differences in the architecture of the endomysium, elastic improvement of the ITL muscle was observed as suggested by an increase of the width of perimysium and improved rheological properties. Our results indicate that ingestion of Col-Pep improves the textural property of ITL muscle of chickens by changing structure of the perimysium.

Relationships between structural characteristics of bovine intramuscular connective tissue assessed by image analysis and collagen and proteoglycan content

Three muscles (Longissimus thoracis, Semimembranosus, Biceps femoris) of 40 young bulls from 3 breeds were used to quantify structural characteristics of bovine connective tissue by image analysis, with both macroscopic and microscopic approaches. Collagen and proteoglycan content was also investigated. Perimysium occupied a greater area (8 vs 6%), and was wider (42 vs 2 μm) and shorter per unit area (1.9 vs 30 mm mm(-2)) than endomysium. Perimysium and endomysium from Longissimus were thinner, less ramified than in Biceps. Longissimus showed less total collagen and cross-linking and more proteoglycans (P<0.0001) than Biceps muscle. Blond d'Aquitaine perimysium occupied less area, was more ramified and muscles contained less collagen, cross-linking and more proteoglycans than Angus (P<0.001). Limousin was intermediate. High proteoglycan content in muscle containing less total collagen suggested a complementarity between these molecules. They might influence mechanical properties of intramuscular connective tissue. This was especially true given that proteoglycans and total collagen were negatively and positively linked with structural parameters, respectively.