| In order to understand the correlation between environment and muscle quality, we investigated the difference of the effects of Honghu ponds and Qingjiang reservoir on morphological characteristics, haematological biochemical, muscle nutritional value and texture profile of channel catfish Ictalurus punctatus reared in ponds and reservoir cages.The crude protein, crude fat, crude ash and moisture of muscle in channel catfish were assayed by biochemical analysis methods.The muscular contents of mineral elements were measured by inductively coupled plasma-atomic emission spectrometry(ICP-AES).The parameters of muscular texture profile, including hardness, springiness, cohesiveness,gumminess, chewiness, and resilience were analyzed using a texture analyzer. Double compression was applied to construct the texture profile analyses(TPA)on raw fillets.The water quality of Honghu pond and Qingjiang reservoir were measured. In order to find the correlation between environment and muscle quality. The present results would provide useful basic data to utilizing reservoir water and to find new ecological farming mode and to get high quality market fish. The main findings were as follows:1. Comparison of water quality of Honghu pond and Qingjiang reservoir on JuneThe total phosphorus of Qingjiang reservoir was just 0.2 mg/L. The total nitrate of Qingjiang reservoir waslower than that in Honghu pond. And no nitrate nitrogen, nitrite nitrogen and ammonia nitrogen was detected.However, p H, transparency, dissolved oxygen and water chemical oxygen consumption of Qingjiang reservoir were significantly higher than thosein Honghu pond. The results have shown that water quality of Qingjiang reservoir was better than Honghu pond.2. Comparison of morphological characteristics of channel catfish reared in ponds and reservoir cagesCompared to the channel catfish in the reservoir group, a significantly higher liver weight and hepatosmatic index were found in the channel catfish of the pond group. The results showed that channel catfish reared in reservoir cages had better nutritional status than the fish reared in ponds.Through the color matching card, we found that back body color of channel catfish reared in ponds was grey. The back body color of channel catfishreared in reservoir was black. The differences of water environment between Honghu pond and Qingjiang reservoir may lead to the differences of body color of channel catfish in two groups.According to the t-test analysis results, the channel catfish in two groups had significantly differences in these Character: 4-5/body length(from termination of dorsal fin to dorsal side of caudal peduncleat the nadir/body length), 6-7/body length(from ventral side of caudal peduncieat the nadir to termination of anal fin/body length),4-7/body length(from termination of dorsal fin to termination of anal fin/body length),4-6/body length(from termination of dorsal fin to ventral side of caudal peduncieat the nadir/body length). According to principal component analysis, we extracted the 3principal components for the channel catfish reared in Qingjiang reservoir.The contribution ration of each component and the contribution ration of cumulative component were 68.823%, 14.725%, 5.239% and 88.786%, respectively. We extracted the 7 principal components for the channel catfish reared in Honghu pond. The contribution ration of each component and the contribution ration of cumulative component were26.165%, 17.130%, 14.660%, 12.642%, 9.858%, 7.929%, 5.000% and93.383%, respectively. The results showed that the body shape of channel catfish of two groups were different. That may be related to the different geographical distance and the water quality between Honghu pond and Qingjiang reservoir.3. Comparison of haematological biochemical in blood of channel catfish reared in ponds and reservoir cagesThere were no significant differences of glucose(Glu), Alanine Aminotransferase(ALT), Aspartate Aminotransferase(AST), Alkaline Phosphatase(ALP),(CHOL) and Albumin(ALB) between the pond group and the reservoir group. Compared to the channel catfish in the pond group, a significantly lower value Triglyceride( TG) and higher total protein(TP) were observed in the catfish in the reservoir group. The results showed that channel catfish reared in reservoir cages have better immune features, and the nutritional status was superior to channel catfish reared in ponds.4. Evaluation of muscle nutrition quality and nutrient compositonss of channelcatfish reared in ponds and reservoir cagesThe results showed that the rate of flesh content in channel catfish reared in either pond or cage group was more than 65%. The channel catfish exhibited higher contents of crude protein and crude ash in the reservoir group than the pond group. A significantly higher crude fat was found in the channel catfish in the pond group.The results showed that channel catfish reared in reservoir cages showed a significantly higher level of threonine, valine, methionine, isoleucine, Leu, phenylalanine and lysine than the channel catfish reared in Honghu ponds. The channel catfish reared in reservoir cages had a higher level of asparagine, glutamic and alanine than the pond group. Compared to the catfish in the pond group, A significantly higher EPA, DHA, C15:0, C17: 1 and n-3 series PUFA was found in the channel catfish of the reservoir group.However,the pond group had a higher C14: 0, C16: 1, C18: 1. The current study suggest that the channel catfish reared in reservoir cages have better muscle quality.Flesh leaching loss increased significantly in the pond group than those in the reservoir group. Compared to the catfish in the pond group, a significantly lower value in either drip loss or liquid loss was observed in the channel catfish in the reservoir group.Compared to the channel catfish in the pond group, the channel catfish of the reservoir group had larger muscle fiber density and smaller muscle fiber diameter.The channel catfish reared either in pond or in reservoir had rich mineral elements content in muscle. Compared to the pond group, a significantly higher content of potassium(K), phosphorus(P), calcium(Ca), magnesium(Mg), zinc(Zn), and iron(Fe)was observed in the reservoir group. However, there were no significant differences in sodium(Na), copper(Cu), manganese(Mn), and chromium(Cr) between the pond group and the reservoir group. No selenium(Se) was detected in fish muscle of both groups.The calcium-phosphorus ratios of muscle in the pond group and the reservoir group were1:22.6 and 1:21.1, respectively.The current study suggest that the channel catfish reared in reservoir cages have more mineral elements content which may be related to the water chemistry, salinity and temperature of Qingjiang reservoir.The hardness, gumminess, and chewiness of muscle enhanced significantly in thecatfish in the reservoir group than those in the pond group. The pond group had significant higher resilience and cohesiveness than the cage group.Given the results, the muscle of channel catfish showed higher water holding capacity in the pond group,whereas the catfish muscle in the reservoir group contained higher protein, lower fat,richer mineral elements content, and higher hardness. |
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