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Kerala Veterinary and Animal Sciences University, Wayanad

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Author: ALPHINE JOSEPH × End date: 2023 × Start date: 2020 × Type: Thesis ×
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    ThesisItemOpen Access
    COMPARATIVE HISTOMORPHOLOGY AND ULTRASTRUCTURE OF THE SKELETAL MUSCLE OF BROILER AND KUTTANAD DUCKS
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR, KERALA VETERINARY ADN ANIMAL SCIENCES UNIVERSITY, 2023-03-23) ALPHINE JOSEPH; Dr. S. Maya
    The present study was conducted to investigate the comparative histomorphology and ultrastructure of the skeletal muscles from selected areas in meat type and spent Kuttanad ducks, to determine the comparative proportion of fibre types in skeletal muscles using histochemical methods and to compare the physical, chemical and mechanical properties of the skeletal muscle between the groups by assessing the correlation of meat quality like tenderness and juiciness with muscle fibre properties. A total of 72 birds comprising of 12 birds each of males and females from broiler Vigova SuperM ducks (six to eight weeks of age), Kuttanad ducklings (six to eight weeks) and spent Kuttanad ducks (over 72 weeks) selected at random were used for the study. Muscle samples from six selected regions, viz. neck (Longus coli posticus- LCP), back (Scapulohumeralis caudalis- SHC), breast (Pectoralis- PEC), wing (Biceps brachii- BB), thigh (Iliofibularis- IF) and drumstick (Gastrocnemius lateralis- GL) were collected from the Meat Technology Unit, College of Veterinary and Animal Sciences, Mannuthy, after humane slaughter, processed appropriately and the data collected were analysed statistically using SPSS version 24.0. Morphologically, the breast muscles were the longest among all muscles. The mean length of the muscles was significantly different between groups, in all the regions. Breast muscle was the heaviest muscle in all the groups and among groups, the heaviest was the pectoralis muscle in Kuttanad duckling males. Mean thickness of muscle was maximum for broiler ducks for the breast muscle. Histologically, the muscle was composed of muscle fibres, connective tissue, blood vessels and nerves in all the groups. The connective tissue covering identified were epimysium, perimysium and endomysium with varying degree of thickness in different muscles. Three types of muscle fibres were identified using enzyme histochemical staining techniques, viz. type I, IIA and IIB. Glycogen content was found copious in type IIB fibres under PAS reaction, while fat droplets in the type I fibres were noticed on Oil red O staining. Alkaline phosphatase and acid phosphatase activity showed negative for muscle fibres indicating the absence of any regenerative or degenerative stages of muscles fibres respectively. The endothelial lining of capillaries amidst the muscle fibres showed a positive reaction for alkaline phosphatase in almost all muscles.On micrometry, maximum average fibre density was observed in breast muscle in spent Kuttanad duck males. In all other regions, the maximum average fibre density was seen in broiler duck males with decreasing order of PEC>SHC>BB>GL>LCP>IF. The maximum average fibre diameter was noticed in breast muscle. In breast, wing and drumstick muscles, broiler ducks showed the maximum average fibre diameter whereas in neck and thigh by Kuttanad duckling males and in back by Kuttanad duckling females. The average fibre diameter from maximum to minimum from PEC>GL>SHC>IF>BB>LCP. Kuttanad duckling males showed the highest mean cross-sectional area of muscle fibres in the neck muscle. The order of average cross-sectional area of different muscles were LCP>IF>SHC>BB>GL>PEC. The average cross-sectional area of muscle fibres was minimum for broiler duck males in all the muscles except breast muscle. However, the mean cross-sectional area did not differ between groups and between genders in the breast muscle. The highest mean fascicle cross-sectional area was obtained for spent Kuttanad duck females in the iliofibularis muscle. Myosin ATPase, SDH and NADH-TR enzyme histochemistry staining of muscle fibres revealed type I, IIA and IIB fibres in neck, back, thigh and drumstick. Type I fibres were noticed concentrated in particular portions of stained tissue sections of back and drumstick muscles. Breast and wing muscles were identified with only type IIA and type IIB fibres. The presence of type I fibres in neck, back, thigh and drumstick musclesand clear absence of type I fibres in wing and breast muscles were confirmed by immunohistochemistry (IHC). Both immunohistochemistry and enzyme histochemistry staining showed relatively similar qualitative results of different fibre types, with IHC method being the more accurate method. Overall, the breast muscle and wing muscle showed type IIA> IIB pattern except in broiler ducks, where the IIA and IIB are found almost equal. The back and drumstick muscles showed IIB>IIA>I pattern. Considering the ratio of IIA and IIB fibres, more IIB fibre component was observed as SHC>GL>BB> PEC. Both in neck and thigh muscles, spent Kuttanad muscle showed more type I fibres followed by broiler ducks and then by Kuttanad ducklings. Neck muscle showed higher proportion of cross-sectional area for type I fibres than thigh muscle. Scanning electron microscopy of muscle fibres revealed the thick and thin filament arrangement of connective tissue amongst muscle fibres. Under transmission electron microscopy, the, myofibrils, sarcomere, triad, myonuclei and interfibrillar, perinuclear and subsarcolemmal mitochondrial populations were identified in the duck muscle. Interfibrillar mitochondrial concentration was comparatively higher in drumstick muscle than breast muscle that too in spent Kuttanad ducks than Kuttanad ducklings.Serum biochemical analysis showed all the parameters examined within the normal level among all the groups indicating the absence of any injury to the muscles. The pre-slaughter live weight, defeathered weight, mean dressed weight were significantly higher in broiler ducks. The mean carcass yields showed significant interaction with a significantly higher values for spent Kuttanad ducks males (77.44 ± 1.50 per cent) than others in male groups. Physical properties of muscle such as colour and pH were analysed in the study. The highest colour L* value was given by back muscle of broiler duck males and the lowest colour L* value was noticed in the breast muscle of male spent Kuttanad ducks. The highest mean colour a* value was obtained for spent Kuttanad duck (14.6 ± 0.13) males in the neck region and the value was significantly higher than other male groups. Mean b* value was maximum for the neck region of broiler duck and in the wing region of spent Kuttanad ducks. The pH of breast muscle had a drastic fall within the first three hours. Initially, the pH was higher in breast muscle in spent Kuttanad duck males and females. The pH of back, thigh and drumstick muscles showed a higher ultimate pH at 24 h. At 15 minutes, the comparison of pH in hot-boned and intact muscle showed significant differences in the wing, back, thigh and drumstick regions. The pH value of intact muscle showed a significantly higher value than hot-boned muscle. Mechanical property of muscle was analysed by measuring the sarcomere length at 15 min, 1 h, 3 h, 6 h and 24 h. At all the intervals, wing muscle showed the highest sarcomere length in broiler ducks. The R value reached to the value of one in almost all muscles within one hour which indicated the fast onset of rigor mortis. R value was higher in neck muscle in spent Kuttanad ducks. The highest mean moisture content was obtained for broiler ducks males in the neck region. The intramuscular fat was obtained highestin the neck muscle by the spent Kuttanad duck females. The collagen content was evidently and copiously detected in the drumstick muscle of Kuttanad duckling males. The highest mean myoglobin content was obtained for drumstick region followed by thigh region in spent Kuttanad duck males. On SDS PAGE analysis, bands were observed in between 180 to 245 kDa molecular weight and the thigh muscle showed thick and differentiated band in all the groups. The migration of myosin heavy chain isoform bands was greatly affected by the quality of the frozen sample and the temperature of the apparatus.The mean flavour scores did not differ significantly between groups except in the thigh region. There was no significant difference observed in the juiciness and mouth coating score between groups and genders. In the back region, the highest mean ease of fragmentation score was obtained for broiler duck males. The overall tenderness score showed significant difference (p<0.05) in breast muscle and back muscle between groups. The overall tenderness score was significantly higher in broiler ducks in the back region. Overall acceptability score was significantly highest in back muscle followed by breast muscle in broiler ducks compared to spent Kuttanad ducks and similar to Kuttanad ducklings. The correlation study showed that the collagen content had significantly positive correlation on muscle fibre length and negative correlation on cross sectional area. The present study indicated that the muscles can be ranked for better meat quality according to the score of individual muscle fibre properties like the proportion of different fibre types, density of fibres and the cross-sectional area of fibres. Apart from that, meat quality was not only affected by a single factor, but by a number of factors and its combinations, that play a major role in the conversion of muscle to meat as well as its tenderness. Differences in muscle fibre properties may be attributed to the anatomical function of particular muscles. In the present study, the different combination of muscle fibre properties like the increased proportion of fibre type IIB, decreased density of fibres and decreased cross sectional area of fibres of the muscle, together resulted in the overall acceptability of the meat from that muscle. Overall, broiler duck showed better meat quality traits than Kuttanad ducks. Since, each muscle was different in muscle fibre properties, selection of breeds with increased quantity of back and breast muscle will increase the quality of duck meat.