| In recent years, due to the constraints of U.S. trade barriers and strong domestic hotpot market demand, channel catfish (Ictalurus punctatus) industry gradually shifting from exports to domestic consumption-dependent. However, the development and utilization of channel catfish was limited, due to its shorter muscle fiber, loose organizational structure and low cook-resistance. Therefore, we try to change the muscle quality and flavor of channel catfish by adjusting the feed composition and feeding style. This paper investigated the effects of broad bean on growth performance, muscle properties and blood physiological-biochemical index of channel catfish (initially weighing about 250 g), taking the channel catfish fed with formula feed as control. The objectives of this study were to supply theoretical basis and experimental data of improving flesh quality and developing a crisp hotpot fillets of channel catfish. The main results were as follows:(1) Growth performance of the channel catfish fed with formula feed and broad bean for 0 days,20 days,40 days,60 days,80 days and 100 days was determined. The growth rate of channel catfish fed with broad bean was 104.85%, which were significantly lower than that of the formula feed group (276.97%). Feed coefficients of the channel catfish fed with formula feed and broad bean were 4.32 and 2.11, protein efficiency of two group were 80.52% and 145.16%, and fat coefficients were 14.72 and 23.83, respectively.(2) Proximate compositions and protein constituents of the muscle from channel catfish fed with formula feed and broad bean were studied during the feeding period. The content of crude ash of the fish muscle from broad bean group and formula feed group exhibited no significant difference (P>0.1). The content of crude protein, crude fat and total sugar of the muscle from broad bean group were significantly lower than these from control group (P<0.01), while moisture content was significantly higher (P<0.01). There were significant differences on protein constituents between broad bean group and feed group. Myofibrillar proteins, alkali-soluble protein, collagen, salt-soluble protein and unsoluble protein of the muscle from broad bean group were significantly higher than that of the feed group, while its sarcoplasmic and soluble protein contents were significantly lower than these from the feed group The contents of P, Ca, Fe and Zn of two experimental groups showed significant differences, P content of broad bean group reduced significantly, but the contents of Ca, Fe and Zn increased significantily. (3) The compositions of muscle amino acids and fatty acid during the feeding period were studied. Total amino acids, essential amino acids and tasty amino acids of of the fish muscle from broad bean group were lower than that of the control group. EAAI of broad bean and the control group were 97.4 and 95.97, respectively. These results indicated that the muscle from channel catfish fed with broad bean exhibited better protein quality, more reasonable amino acid composition, compared to the control group.The content of unsaturated fatty acids of the fish muscle from the broad bean group was lower than that from the control group in the same feeding period. After 100 days of feeding, the content of fatty acids of channel catfish fed with the broad bean and formula feed were 3206.5 mg/kg and 3294.2 mg/kg, and the content of unsaturated fatty acids contents were 2206.2 mg/kg and 2382.4 mg/kg respectively. The contents of fatty acids and unsaturated fatty acids were lower than these of the control group.(4) Textural properties of the dorsal muscles (fresh, steamed and boiled muscles) of channel catfish fed with broad bean and formula feed during the feeding period were analyzed. Whether or not the muscle was fresh, steamed or boiled, the hardness, resilience, springiness and chewiness of muscle from broad bean group were higher than that from the formula feed group. This result suggested that the textural properties of channel catfish flesh had significantly changed after feeding broad bean, and the muscle of channel catfish from the broad bean group had been crisped.(5) The thermal properties and microstructure of the muscle of channel catfish were studied. After 100 days of feeding, the freezing temperature of the muscle of channel catfish from broad bean group and formula feed group were -11.64℃and -11.85℃, and the freezing point were -1.84℃and -2.13℃, respectively. The freezing temperature and freezing temperatures of fish muscle from broad bean group were higher than that from the formula feed group. The denaturation temperature of myosin, sarcoplasmic and actin of fish muscle from broad bean group was significantly lower than that from formula feed group.No significant difference of basic structure of the muscle of channel catfish was observed between broad bean group and formula feed group. However, the microstructures of muscle bundle and myofibril of channel catfish were different between two feeding groups. The shapes of cross sectional of myofibrils were more irregular, the area was bigger, and the muscle sheath was thicker. Judging from vertical section, broad bean group has more regular myofibril, more longer sarcomere and more clearer dark-light band, compared to the formula feed group. (6) Blood physiological-biochemical of channel catfish fed with broad bean and formula feed were analysed during the feeding period. RBC and WBC of channel catfish fed with broad bean significantly reduced compared to the formula feed group. TG, TC, ALP and GLU in blood of broad bean group were lower compared with the formula feed group, and the content of blood calcium was significantly higher than that of the formula feed group. Lysozyme activity and antibody titer of broad bean group were lower, and leucocyte phagocytic index was slightly lower compared with the formula feed group. This showed that immune function of channel catfish fed with broad bean declined significantly. |
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