Intramuscular Collagen Research Articles

Nutritional and sensorial meat quality of different selected Japanese quails (Coturnix coturnix japonica)

Descendents of S18 generation of Japanese quails (Coturnix coturnix japonica), selected for low (line 11, n=15) or high (line 12, n=6) yolk cholesterol content, egg type (line 13, n=15), and meat type (line 8, n=15) chosen as unselected control, were used for this experiment to study performance as well as nutritional and sensorial meat quality. The lowering of yolk cholesterol content in the line 11 was 313 mg/100 g yolk, and the increasing of yolk cholesterol content in the line 12 was 116 mg/100 g yolk, i.e. -17.25 %, and +6.39% in comparison to parental line 13, respectively. Quail-chicks were grown in a deep litter floor up to 35 days of age, under continuous lighting, with water and feed (a commercial diet) ad libitum until 12h before slaughtering, when feed was withdrawn. The body weight of the quails was controlled every week (from week 1 to 5). At the end of the experiment, all the birds were slaughtered (at avg. weight of 209.3a vs 104.0b, 107.7b and 110.6b g for lines 8, 11, 12 and 13, respectively; P<0.001) the hot carcass weight was recorded and dressing percentage was calculated. Pectoralis superficialis muscles were removed from the carcasses immediately after slaughter to assess intramuscular collagen (IMC) properties (collagen and crosslink concentrations), cholesterol and intramuscular lipid contents. For IMC analyses, muscles were trimmed of fat and epimysium, lyophilized, and hydrolyzed in 6N HCl for determination of hydroxyproline and hydroxylysylpiridinoline (HLP) crosslinks, which are considered as main connective tissue components influencing meat tenderness. Intramuscular fat content was determined by histochemical method. The samples were cut in cryostat into 10_m thick sections and stained by red oil method to differentiate intramuscular fat content. Multiscan v.14.02 Image Analysis System was used to define the intramuscular fat content. Data were submitted to one-way ANOVA. Quails of line 8 had the highest (P<0.01) growth and carcass weight (129.1 g) than those of the others lines. Dressing percentage was not affected (P>0.05) by different selection (ranging from 57.7 to 61.8%). The selection on yolk cholesterol content did not affect (P>0.05) the intramuscular lipid (1.48, 2.00, 1.76 and 2.54% for lines 8, 11, 12 and 13, respectively) and cholesterol muscle content (33.3, 27.8, 43.4 and 36.7 mg/100g lines 8, 11, 12 and 13, respectively). However, the meat of the quails selected for low cholesterol in the egg yolk (line 11) contained less cholesterol than that of the other birds, especially with respect to animals of line 12 (-35.9%), characterized by high cholesterol in the egg yolk. Collagen and muscle HLP concentrations (µg/mg) and the degree of collagen maturation, expressed as HLP crosslink (mol HPL/mol collagen), were not influenced by different selection. However the amount of collagen (ranging from 17.25 to 18.90 µg/mg) and crosslink (ranging from 0.141 to 0.175 mol HPL/mol collagen) found in the meat of this species if compared to those of poultry IMC are different. Results from the present study suggest, as expected, that quails of line 8 (meat type) showed better growth performance. Meat from Line 11 quails may be sensitive to less cholesterol content. In addition, considering the lower fiber collagen stability (mol HLP/mol collagen) found in this meat, we would expect a positive effect on meat tenderness.

The effect of dietary energy and vitamin E administration on performance and intramuscular collagen properties of lambs

The effect of different dietary energy levels, with or without injections of vitamin E, on growth, carcass traits and intramuscular collagen (IMC) characteristics of growing lambs was studied. Twenty-four Ile de France ram lambs were evaluated in a 2 × 2 factorial design involving different DL-α-tocopheryl acetate injections (C, control = 0 and V = 150 IU/wk, i.m. for eight wk) and energy level (N, normal = 7.61 and L, low = 6.47 MJ/kg DM). Growth and slaughter performance, and IMC characteristics were not influenced by diet. DL-α-tocopheryl acetate increased ADG during suckling, while it did not affect live weight, carcass weight and dressing percentage. Vitamin E injections reduced carcass shrinkage but also had a negative effect on pelvic limb percentage. The Longissimus muscle pH values were higher in V than in C lambs. DL-α-tocopheryl acetate reduced IMC maturity and muscle hydroxylysylpyridinoline crosslink concentration, more markedly in lambs fed low energy diets.

Effects of nutritional level on muscle development, histochemical properties of myofibre and collagen architecture in the pectoralis muscle of male broilers

1. The effects of nutritional level on muscle development, histochemical properties of myofibre and collagen architecture in the pectoralis muscle were evaluated using male broilers of Red Cornish × New Hampshire stock, reared on diets of high nutritional value for up to 80 d (H80d) and low nutritional value for up to 80 d (L80d, same age as H80d) or 95 d (L95d, same body weight as H80d). 2. The total live weight and the weight of pectoralis muscle were lower in L80d than in both H80d and L95d. The muscle weight as a percentage of live weight was 8·7% in L80d, 10·7% in H80d and 11·5% in L95d. 3. Pectoralis muscle was composed only of type IIB myofibres and showed no differences in myofibre type composition among the chicken groups. The largest diameter of type IIB myofibres was observed in L95d, followed by H80d and the smallest in L80d. 4. The total amount of intramuscular collagen did not differ among the chicken groups (1·92 to 1·99 mg/g). Types I and III collagens were immunohistochemically detected in both the perimysia and endomysia. The thin perimysia around the primary myofibre fascicles showed larger width in H80d than L80d and L95d, and also the thick perimysia around the secondary fascicles in H80d than L80d. 5. The collagen structure of the perimysium was most developed in H80d, followed by L95d and on the least in L80d. The development of perimysial collagen fibres could be enhanced by a rapid growth rate of the muscle induced by high nutritional level and depressed by a slow growth rate with low nutritional foods. 6. The endomysial collagen architecture was observed as a felt-like tissue of the fibril bundles with many slits. The thinnest endomysial wall was observed in L80d, followed by H80d and the thickest in L95d. 7. From these results, it was indicated that foods of high nutritional value could enhance growth of the pectoralis muscle of broilers, and this is accompanied by hypertrophy of the type IIB myofibres and development of the perimysial collagen architecture.

Increased injury and intramuscular collagen of the diaphragm in COPD: autopsy observations

Evidence for diaphragm injury in people with chronic obstructive pulmonary disease (COPD) has been reported, although the extent of injury and collagen accumulation post mortem have not previously been examined. In addition, it is not known whether the amount of injury and collagen are different in key regions of the diaphragm. The cross-sectional area of collagen and the percentage of abnormal myofibres in the post mortem diaphragm and psoas major were determined by computer-assisted image analysis of stained cross-sections of the diaphragm for collagen with picrosirius red and with haematoxylin and eosin for morphology. In the midcostal diaphragm of six subjects with COPD and six subjects with no significant respiratory disease, the COPD diaphragm displayed a greater cross-sectional area of collagen and percentage of abnormal myofibres (collagen: 24.2+/-1.0 versus 18.6+/-1.1%; injury: 28.4+/-7.2 versus 12.0+/-1.3%). In 18 patients with various respiratory conditions, the midcostal diaphragm displayed more collagen and abnormal myofibres than the crural diaphragm, while both costal and crural diaphragms displaying more collagen and abnormal myofibres than psoas major. This study reveals extensive injury and collagen accumulation in the chronic obstructive pulmonary diseased diaphragm, and reveals a regional pattern of injury and intramuscular collagen which may correspond to variations in diaphragm loading.

No effect of menstrual cycle on myofibrillar and connective tissue protein synthesis in contracting skeletal muscle

We tested the hypothesis that acute exercise would stimulate synthesis of myofibrillar protein and intramuscular collagen in women and that the phase of the menstrual cycle at which the exercise took place would influence the extent of the change. Fifteen young, healthy female subjects were studied in the follicular (FP, n=8) or the luteal phase (LP, n=7, n=1 out of phase) 24 h after an acute bout of one-legged exercise (60 min of kicking at 67% W(max)), samples being taken from the vastus lateralis in both the exercised and resting legs. Rates of synthesis of myofibrillar and muscle collagen proteins were measured by incorporation of [(13)C]leucine. Myofibrillar protein synthesis (means+/-SD; rest FP: 0.053+/-0.009%/h, LP: 0.055+/-0.013%/h) was increased at 24-h postexercise (FP: 0.131+/-0.018%/h, P<0.05, LP: 0.134+/-0.018%/h, P< 0.05) with no differences between phases. Similarly, muscle collagen synthesis (rest FP: 0.024+/- 0.017%/h, LP: 0.021+/- 0.006%/h) was elevated at 24-h postexercise (FP: 0.073+/- 0.016%/h, P<0.05, LP: 0.072+/- 0.015%/h, P<0.05), but the responses did not differ between menstrual phases. Therefore, there is no effect of menstrual cycle phase, at rest or in response to an acute bout of exercise, on myofibrillar protein synthesis and muscle collagen synthesis in women.

Urinary and plasma organic acids and amino acids in chronic fatigue syndrome

Previous work by others have suggested the occurrence of one or more chemical or metabolic ‘markers’ for ME/CFS including specific amino acids and organic acids and a number of unidentified compounds (CFSUM1, CFSUM2). We have shown elsewhere that CFSUM1 is partially derivatised pyroglutamic acid and CFSUM2 partially derivatised serine and have suggested and demonstrated that the analytical methods used were unsuitable to identify or to accurately quantify urinary metabolites. We have now made a detailed analysis of plasma and urinary amino acids and of urinary organic acids from patients with ME/CFS and from three control groups. Fasting blood plasma and timed urine samples were obtained from 31 patients with CFS, 31 age and sex-matched healthy controls, 15 patients with depression and 22 patients with rheumatoid arthritis. Plasma and urinary amino acids and urinary organic acids were determined using established and validated methods and data compared by statistical analysis. None of the previously reported abnormalities in urinary amino acids or of organic acids could be confirmed. Results however provide some evidence in patients with ME/CFS for underlying inflammatory disease and for reduced intramuscular collagen with a lowered threshold for muscle micro-injury. These factors in combination may provide a basis for the fatigue and muscle pain that are the major symptoms in these patients.

Effects of T-Lymphocyte Depletion on Muscle Fibrosis in the mdx Mouse

Duchenne muscular dystrophy was initially described as a myosclerosis because of the conspicuous progression of interstitial fibrosis. Using the mdx mouse homologue, we have shown previously that the accumulation of intramuscular collagen is profoundly influenced by the presence or absence of T lymphocytes. Here we have used thymectomy and antibody depletion to examine the effect of ablating CD4 or CD8 or both subsets of T lymphocytes on skeletal muscle fibrosis in mdx and C57BL10 (wild-type) mice. Depletion of either or both subsets at 4 weeks of age did not influence fibrosis in mdx mice, as determined by measuring hydroxyproline levels and collagen deposition in diaphragm. Additionally, expression of transforming growth factor-beta1, which is implicated in collagen deposition, either decreased (mdx mice) or increased (C57BL/10 mice) after double CD4/8 depletion. Our data suggest that depletion of lymphoid cells may affect the tight regulatory control of transforming growth factor-beta1, with possible pleiotropic effects, and more importantly, that the fibrotic process is self-sustaining from a very early stage.

Effects of pre‐slaughter nutritional condition on intramuscular collagen solubility, pyridinoline cross‐links and meat tenderness in aged goats

ABSTRACTEffects of preslaughter nutritional condition on intramuscular collagen characteristics were studied, in order to clarify the potential of intensive feeding to aged animals in improving meat tenderness. Ten castrated male goats were assigned into one of two groups: one group was allowed ad libitum access to a concentrate diet (total digestible nutrients 70%, crude protein 15%) and Italian ryegrass hay (ADLIB‐group), and the other group was fed a restricted amount of their diet (concentrate diet 0.5% of bodyweight/day; hay 1.5% of bodyweight/day) to maintain their bodyweight (MAIN‐group). After 3 months of the experimental period, goats were slaughtered and meat samples were obtained immediately. Goats in ADLIB‐group had lower total and insoluble collagen concentrations, higher fat concentrations and collagen solubility than those in MAIN‐group, but soluble collagen concentrations of muscles were similar for both groups. Goats in ADLIB‐group had lower pyridinoline concentrations than those in MAIN‐group, in all muscles, but the differences of pyridinoline concentration between the groups were not statistically significant. Warner‐Bratzler shear force values of Longissimus and Biceps femoris muscles were lower in ADLIB‐group than in MAIN‐group. The increase of meat tenderness by preslaughter intensive feeding seemed to be associated with the increase in intramuscular fat deposition and high collagen solubility, and pyridinoline cross‐link appeared to be one of the factors related to collagen solubility.

Effect of Endurance Exercise on Intramuscular Collagen Characteristics in Goats

Effect of Endurance Exercise on Intramuscular Collagen Characteristics in Goats

Collagen and muscle pathology in fibromyalgia patients.

To measure collagen concentration and search for muscle pathology in muscle non-tender-point areas from fibromyalgia (FM) patients. Muscle biopsies were obtained from m. vastus lateralis of 27 carefully selected, female fibromyalgia patients, and from eight age-matched female control subjects. Amino acids were determined by HPLC and electron microscopy was performed. The FM patients had lower hydroxyproline and lower total concentration of the major amino acids of collagen than the controls. No significant difference was seen in the concentration of the major amino acids of myosin or of total protein. Electron microscopy showed no significant differences between FM patients and controls although atrophied muscle fibrils occurred in FM patients only, but frequencies were not significantly different. Fibromyalgia patients had a significantly lower amount of intramuscular collagen. This may lower the threshold for muscle micro-injury and thereby result in non-specific signs of muscle pathology.

Influence of dietary conjugated linoleic acids (CLA) and age at slaughtering on meat quality and intramuscular collagen in rabbits

To assess the effects of dietary conjugated linoleic acids (CLA) on meat composition and intramuscular collagen (IMC), 144 New Zealand White rabbits, half males half females, 55 days old (1.8 kg LW), were assigned to three weight- and sex- balanced groups and given the following dietary supplements: 0.5% sunflower oil, (C); 0.25% sunflower oil plus 0.25% CLA (T1); and 0.5% CLA (T2). The CLA was prepared from sunflower oil and contained 65% CLA isomers, half cis-9, trans-11 and half trans-10, cis-12. Six males and six females from each group (total 36) were slaughtered at 76, 90 and 104 days of age (corresponding to 2.5, 2.8, and 3.1 kg BW, respectively). The lean fraction was higher and the water content significantly higher in the meat of T2 compared to C and T1 for all ages combined. At the third slaughtering (104 days) the meat fat content was significantly lower in group T2. For all ages combined, IMC content, IMC hydroxylysylpyridinoline (HLP) concentration (index of collagen cross-linking) and IMC maturity (HLP/IMC) were significantly lower in the intermediate supplementation group (T1) compared to C and T2, and were also lower in animals slaughtered at 90 days. CLA supplementation has limited effects on the chemical composition of rabbit meat, with positive effects on meat texture and tenderness after supplementation up to 35 days at 0.25%, and a significant decrease in fat content only at high slaughter weight and high supplementation level (0.5%).

Perimysial collagen crosslinking and meat tenderness in Belgian Blue double-muscled cattle

The relationship between intramuscular collagen and five collagen crosslink concentrations, and the tenderness of meat from Belgian Blue normal, heterozygous double-muscled (DM) and homozygous DM cattle was investigated using M. semitendinosus (St) and M. gluteobiceps (Gb). The histidinohydroxymerodesmosine (HHMD) concentration (per mol collagen) in St was less in DM animals than normal animals. Concentrations (per gram of wet meat) of HHMD and Erlich chromogen (EC) in Gb, and HHMD, EC, dihydroxylysinorleucine (DHLNL) and hydroxylysinorleucine (HLNL) in St were also lower in DM animals than normal animals. Shear force of raw meat was significantly greater in normal animals than DM for both muscles; cooked meat shear force was greater in the normal animals for the Gb muscles only, showing a good correlation with sarcomere length. Most correlations between shear force and collagen or crosslink concentrations were not significant and those that were highly significant were generally weak.

Ontogenetic changes in fibrous connective tissue organization in the oval squid, Sepioteuthis lessoniana Lesson, 1830.

Ontogenetic changes in the organization and volume fraction of collagenous connective tissues were examined in the mantle of Sepioteuthis lessoniana, the oval squid. Outer tunic fiber angle (the angle of a tunic collagen fiber relative to the long axis of the squid) decreased from 33.5 degrees in newly hatched animals to 17.7 degrees in the largest animals studied. The arrangement of intramuscular collagen fiber systems 1 (IM-1) and 2 (IM-2) also changed significantly during ontogeny. Because of the oblique trajectory of the IM-1 collagen fibers, two fiber angles were needed to describe their organization: (1) IM-1(SAG), the angle of an IM-1 collagen fiber relative to the squid's long axis when viewed from a sagittal plane and (2) IM-1(TAN), the angle of an IM-1 collagen fiber relative to the squid's long axis when viewed from a plane tangential to the outer curvature of the mantle. The sagittal component (IM-1(SAG)) of the IM-1 collagen fiber angle was lowest in hatchling squid (32.7 degrees ) and increased exponentially during growth to 43 degrees in squid with a dorsal mantle length (DML) of 15 mm. In squid larger than 15 mm DML, IM-1(SAG) fiber angle did not change. The tangential component (IM-1(TAN)) of IM-1 collagen fiber angle was highest in hatchling squid (39 degrees ) and decreased to 32 degrees in the largest squid examined. IM-2 collagen fiber angle (the angle of an IM-2 collagen fiber relative to the outer surface of the mantle) was lowest in hatchling squid (34.6 degrees ) and increased exponentially to about 50 degrees in 15-mm DML animals. In squid larger than 15 mm DML, IM-2 fiber angle increased slightly with size. The volume fraction of collagen in IM-1 and IM-2 increased 68 and 36 times, respectively, during growth. The ontogenetic changes in the organization of collagen fibers in the outer tunic, IM-1, and IM-2 may lead to ontogenetic differences in the kinematics of mantle movement and in elastic energy storage during jet locomotion.

Growth, slaughter and intra-muscular collagen characteristics in Garganica kids

Growth performance, ossification of metacarpal growth plate, and intra-muscular collagen characteristics in three muscles of 10 intact male Garganica kids were studied. Each week, starting from the 47th day of age to slaughter (75th day of age), kids were weighed and blood samples taken for plasma non-protein hydroxyproline analysis. At slaughter, metacarpal, metatarsal bones and metacarpal growth plate thickness were measured. The semitendinosus (ST), semimembranosus (SM), and rectus medialis (RM) muscle samples were analysed for collagen concentration and hydroxylysyl pyridinoline (HP) cross-links. ST muscle had a collagen amount higher than SM and RM ( P<0.01), and RM muscle had the highest ( P<0.01) HP concentration. Tenderness index was the highest ( P<0.01) in RM muscle. Animal growth rates slowed, starting from 61st day of age ( P<0.01); this trend coincided with a marked reduction in concentration of plasma non-protein hydroxyproline ( P<0.01). In addition, plasma non-protein hydroxyproline concentration was positively correlated ( r=0.61, P=0.001) with growth rate of animals, suggesting that collagen turnover decreases during a slow growth phase. Based on the metacarpal growth plate width, the rate of bone ossification appears to be slower in goats than sheep.

Development and ageing of intestinal musculature and nerves: the guinea-pig taenia coli.

The fine structure of taenia coli was studied by electron microscopy in guinea-pigs from birth to old age (over 2 years old). Smooth muscle cells are approximately 1,000 microm(3) in volume at birth, 2,200 microm(3) in young adults and 4,500 microm(3) in old age. Muscle growth and muscle cell enlargement continue throughout life, an increase in muscle volume of about 240 times. Differentiated muscle cells divide during development and in adults. Because mitoses are found in any part of the muscle, the tissue grows from within, rather than by addition at the ends or borders. There is progressive increase in nucleus volume, and decrease in surface-to-volume ratio and in nucleus-cell volume ratio in muscle cells. At all ages the taenia consists of a uniform population of muscle cells (apart from dividing cells); there are no undifferentiated cells, no precursor cells or myoblasts, and no degenerating cells. Interstitial cells and fibroblasts are observed at all ages with only small variations in relative number. The amount of intramuscular collagen increases in old age. There is roughly one capillary for every 170 muscle cell profiles at birth, and one for every 200 in adults and in old age. The innervation is dense and reaches all parts of the muscle. In adults there are approximately 1,300 axons per 10,000 microm(2) of sectional area, or between 8,000 and 38,000 axons in a full cross section of taenia; this amounts to approximately 2% of the muscle volume. An answer to the question of why there are so many nerves in the taenia was not found. Expanded axon profiles are part of typical varicose fibres. Varicosities are packed with small clear vesicles and lie at the surface of nerve bundles. Absence of strong, constant patterns indicating specialized contacts of the nerve terminals is a feature of these nerves at all ages. Some varicosities are closest to interstitial cells; more commonly they are close to muscle cells at sites that strongly suggest a neuro-muscular junction. The additional possibility that some varicosities are part of afferent fibres is discussed. The innervation is well developed at birth and the highest density of innervation is found around day 4 when 4% of the taenia consists of nervous tissue. The innervation of immature taenia is characterized by close juxtaposition of axons and muscle cells. Axon profiles packed with vesicles, varicosities and presumptive neuro-muscular junctions are present at birth. The extent of Schwann cells in intramuscular nerves is markedly less than in adults, and virtually all the axons have maximal membrane-to-membrane contact with other axons. In taenia of aged guinea-pigs, the density of innervation is reduced. There is no actual loss of nerve tissue; the total amount of nerve tissue is greater than in young adults, and the apparent reduction reflects a more intense growth of muscle cells. The Schwann cell component becomes more conspicuous than in young adults and there is a greater number of axons fully wrapped by a Schwann cell. Presumptive neuro-muscular junctions are common and probably commoner than in young adults. Growth of muscle cells, changes in their cytological features and in the stroma occur throughout life, including old age. Nerves too continue to grow and undergo structural changes in pattern of distribution, relation with Schwann cells and effector cells.

Effects of animal and muscle characteristics on collagen and consequences for ham production

The effect of biological and technological factors on ham production were studied by analyzing collagen pyridinoline cross-linking and the thermal stability of type I collagen. The type of muscle affected hydroxylysylpyridinoline ( P>0.01) and lysylpyridinoline ( P<0.001) cross-linking, total intramuscular collagen concentration ( P<0.0001), and the slope of type I collagen solubility as a function of time. pH ( P<0.05) and genetic line ( P<0.0001) affected lysylpyridinoline cross-linking. In ham production, muscle type, pH 24, nitrite salt concentration and pasteurization value affected type I collagen solubility ( P<0.0001). There was a relationship between pyridinoline cross-linking and soluble type I collagen levels and between technological yield and soluble type I collagen concentration ( P<0.0001). There was also a relationship between collagen pyridinoline cross-linking and technological yield if the nitrite salt (1.5%) and pH 24 (<5.55) were kept constant. Thus collagen solubility and pyridinoline content are two indicators of meat quality in ham production.

Composition and protein fractions of different meat by-products used for petfood compared with mechanically separated chicken (MSC)

Pork by-products (lung lobes, kidneys), chicken viscera (head, feet and viscera) and mechanically separated chicken (MSC) were evaluated for proximate composition, protein distribution and connective tissue. Proximate composition varied among meat by-products and MSC. Pork by-products contained the most crude protein ( p<0.05). Low levels of high ionic strength soluble (HIS) proteins were obtained from meat by-products. Pork lungs and chicken viscera contained the greatest amounts of insoluble (IN) proteins ( p<0.05). Total collagen values were positively correlated to IN proteins, intramuscular collagen (IMC) and elastin. Types I and III collagen could not be detected by SDS-PAGE for the different meat by-products though collagen solubility appeared to be significant. These results suggest functional property differences between specific by-products are likely when used in petfood product formulations.

Changes in intramuscular connective tissue and collagen solubility of bovine m. semitendinosus during retorting

Vacuum-packed slices of bovine m. semitendinosus (ST) muscle were retorted to internal temperatures of 50, 60, 70, 80, 90, 100 and 121°C. Changes in the microstructure of the endomysium and perimysium were evaluated using a scanning electron microscope (SEM). Changes in solubility of intramuscular collagen were also estimated. In samples heated to 50°C changes in intramuscular connective tissue were not seen. At 60°C granulation of the perimysium and sarcolemma was seen, and on longitudinal sections, as well as granulation, fibrous structures of perimysium were observed. At 70°C increased granulation was observed. In the range 80–121°C progressive compression of the meat structure was seen in the transverse sections. The percentage of soluble collagen in the meat changed little up to an internal temperature of 60°C, but at 70°C it almost doubled, and in the range 80–121°C drastically decreased.

Influence of multiple injections of vitamin E on intramuscular collagen and bone characteristics in suckling lambs.

We studied the influence of vitamin E on intramuscular collagen characteristics and on metacarpal growth plate evolution in suckling lambs. Twenty-four 5-d-old Ile de France suckling male lambs were divided into four equal weight groups, and weekly i.m. injections of DL-alpha-tocopheryl acetate (Control group, 0 IU; Group 1, 625 IU; Group 2, 1,000 IU; and Group 3, 1,500 IU) were given until the lambs were 33 d old. Blood samples were withdrawn for plasma alpha-tocopherol, cholesterol, and triglyceride analyses when the lambs were slaughtered at 40 d of age. Hot carcass weight, metacarpal and metatarsal bone characteristics, and metacarpal growth plate width were measured. After 24 h at 2 to 4 degrees C, semitendinosus muscles were removed for intramuscular collagen analyses. Weight was not influenced by treatment, but lambs in Group 1 had a higher (P < .01) intramuscular collagen content than the other groups. A positive quadratic correlation was found between total collagen and vitamin E doses (r = .511; P < .05). Amount and percentage of soluble collagen increased in muscles of all three vitamin E-treated groups compared with the control group. However, hydroxylysyl pyridinoline concentration decreased with vitamin E injection, but the difference compared to control lambs was only significant for the group injected with 1,000 IU. Amount of soluble collagen was strongly correlated to total collagen concentration (r = .879; P < .0001). It was also related to the alpha-tocopherol/(cholesterol + triglycerides) ratio in plasma (r = .431; P < .04). However, the correlation between soluble collagen percentage and alpha-tocopherol concentration in plasma was not significant (r = .369; P < .08). Bone length, weight, and diameter did not change, but the thickness of metacarpal growth plate increased as the DL-alpha-tocopheryl acetate dose increased; in Groups 2 and 3, the growth plate was significantly wider than in Group 1 and the controls. Growth plate width correlated with alpha-tocopherol/(cholesterol + triglycerides) ratio in plasma (r = .481; P < .02).

The effects of age at slaughter, genotype and finishing system on the biochemical properties, muscle fibre type characteristics and eating quality of bull beef from suckled calves

AbstractMuscle fibre characteristics and biochemical properties of muscle recovered from young bulls of two genotypes (Aberdeen Angus × and Charolais ×), reared on two different diets (silage-based and barley-based) and slaughtered at varying ages between 10 and 19 months of age were established. These analyses were restricted to samples ofm. longissimus lumborum (LI) recovered at 48 h post mortem, vacuum packed and stored at 2°C for 14 days. Biochemical measurements included intramuscular fat content, intramuscular collagen content and its solubility, haem pigment concentration, sarcomere length and myofibril fragmentation. Muscle fibre type was classified according to the contractile nature of thefibres and their metabolic properties.Intramuscular fat content increased (P &lt; 0·01) with age at slaughter and at a fixed age was greater for Angus × than Charolais × bulls (211·5 v. 295·8 mg/g dry matter, P &lt; 0·01). Total intramuscular collagen and its solubility tended to decrease with age (P &lt; 0·01). Differences in haem pigment concentration in samples of LI were detected between genotype (3·99 v. 3·59 mg/g for Angus × and Charolais × bulls; P × 0·01) and diet (3·97 v. 3·62 mg/g for bulls given barley and silage; P &lt; 0·01), and increased with age at slaughter (P &lt; 0·01). There was a significant increase in eye muscle cross-sectional area with increasing slaughter date (P &lt; 0·01) and this was paralleled by an increase in cross-sectional area of individual muscle fibres (P &lt; 0·001). Differences in cross-sectional area of individual muscle fibres between genotype and diet were small and inconsistent. Charolais × bulls had a greater percentage area of fast twitch glycolytic fibres than Angus × bulls (54·3 v. 49·3%; P &lt; 0·01) and a smaller percentage area of slow twitch oxidative fibres (15·8 v. 18·9%; P &lt; 0·05). Beef tenderness was positively correlated (r = 0·48; P &lt; 0·01) with the frequency of slow twitch oxidative fibres and negatively correlated (r = -0·38; P &lt; 0·05) with the frequency offast twitch glycolytic fibres.