A method for estimating the organ weight of healthy tilapia and its application

Abstract

This invention relates to a method and application for estimating the organ weight of healthy tilapia, belonging to the field of aquatic animal experimental technology. The method provides a functional relationship between the body weight of healthy tilapia and the weight of various organs. This invention also provides a method for evaluating the effectiveness of tilapia animal experiments using the aforementioned method. The method involves measuring the weight of tilapia at each stage of the experiment, using the method to estimate the organ weights corresponding to the healthy tilapia at that body weight, obtaining the organ weights of the experimental tilapia, and evaluating the impact of experimental factors on the various organs of the tilapia based on the obtained organ weights corresponding to the healthy tilapia at that body weight. This invention provides an accurate method for evaluating the impact of experimental factors on the organs of tilapia in animal experiments.

Description

Technical Field

[0001] This invention belongs to the field of aquatic animal experimental technology, and in particular relates to a method and application for estimating the weight of organs in healthy tilapia. Background Technology

[0002] In various research fields, such as studying the effects of animal feed, the chronic toxicity of drugs or harmful chemicals, and pathological changes, changes in animal organ weight are important reference indicators. Because organ weight is inherently affected by the size of the animal's body, simply comparing the absolute weight of organs between different experimental groups is insufficient to reflect the true experimental results. Therefore, researchers typically use changes in the ratio of organ weight to body weight, or the weight of an organ (e.g., the brain) that is relatively constant relative to a certain weight, to reflect the effects of external factors such as pathogens, feed, and drugs on the organism. The ratio of organ weight to body weight, also known as the organ coefficient, has been widely used in toxicology and aquatic animal physiological and pharmacokinetic models. However, in long-term toxicity experiments, body weight gain is easily affected by toxicity, and using changes in the organ coefficient to judge toxic effects may be biased. By studying the relationship between organ weight and body weight and establishing a regression equation, body weight can be used to predict the organ weight of healthy animals, thereby assessing the impact of experimental factors on animal tissues and organs.

[0003] The organ coefficient indicates a linear relationship between the weight of an animal's tissues and organs and its body weight. However, current research shows that this relationship varies across different species and even among different organs within the same species. For example, in studies of the leopard toadfish (Opsanus tau), logarithmic functions were found to predict organ weight more accurately from body weight than linear equations (Robinson et al., 1960). Power function formulas showed good fitting results for the heart weight of various freshwater wild fish species in Chesapeake Bay and nearby freshwater rivers (Wilber et al., 1961). In studies of the long-clawed gerbil (Meriones unguiculatus), it was found that the optimal functional relationship between the weight of different organs and body weight differed within the same species: the heart and spleen showed a linear relationship, the kidneys and lungs showed an allometric relationship, and the testes and liver showed a logarithmic relationship (Wilber and Gilchrist, 1965). Researchers have also discovered in their studies of the spotted pufferfish (Sphaeroides maculatus) that brain weight exhibits a hyperbolic relationship with body weight, meaning that brain weight increases to an asymptote (Wilber and Schneider, 1967). Currently, there is limited research in this area of ​​fish studies, and most existing research focuses only on individual organs of specific sizes within a particular species, especially tilapia, a major farmed species, lacking a systematic approach. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method and application for estimating the organ weight of healthy tilapia. The method can predict the weight of the organs of a healthy tilapia at the time of the experiment, in order to assess the impact of experimental factors on the organs of the experimental tilapia.

[0005] This invention is achieved through the following technical solution:

[0006] A method for estimating the organ weight of a healthy tilapia, comprising the following steps: measuring the tilapia's current body weight and calculating the weights of blood, heart, kidneys, stomach and intestines, gills, skin, gallbladder, scales, muscles, and gonads using the following formula; the formula for calculating blood is y = 0.0828x. 0.771 The formula for calculating the heart's diameter is y = 0.00160x. 0.951 The formula for calculating the liver is y = 0.0280x. 0.872 The formula for calculating the kidney is y = 0.00387x. 0.820 The formula for calculating the spleen is y = 0.00167x. 0.972The formula for calculating gastrointestinal function is y = 0.0511x. 0.808 The formula for calculating gills is y = 0.0556x. 0.911 The formula for calculating skin thickness is y = 0.0152x. 1.122 The formula for calculating the gallbladder size is y = 0.00730x. 1.060 The formula for calculating the scale size is y = 0.0749x. 0.865 The formula for calculating muscle mass is y = 0.353x. 1.053 The formula for calculating the gonads is y = 0.000393x 1.202 , where x is body weight and y is the weight of each organ.

[0007] The method described above is used to evaluate the experimental results. The method involves measuring the weight of tilapia at each stage of the experiment, evaluating the organ weights of healthy tilapia at that weight, obtaining the organ weights of the experimental tilapia, and assessing the impact of experimental factors on the various organs of the tilapia based on the calculated organ weights of healthy tilapia at that weight.

[0008] The beneficial effects of this invention compared to existing technologies are as follows: The method of this invention can directly and accurately obtain the weights of blood, heart, kidneys, stomach, gills, skin, gallbladder, scales, muscles, and gonads of healthy tilapia at a given weight. In tilapia animal experiments, the weight of tilapia is measured at each stage of the experiment, and the weight of the organs corresponding to that weight in healthy tilapia is assessed using the method described above. The weights of the experimental tilapia organs are then obtained, and the impact of experimental factors on the various organs of the tilapia is evaluated based on these organ weights. This invention provides an accurate method for assessing the impact of experimental factors on the organs of tilapia in animal experiments. Attached Figure Description

[0009] Figure 1 The graph shows the power function equations and scatter plots of body weight versus the weight of various tissues and organs; A represents blood, B represents heart, C represents liver, D represents kidney, E represents spleen, F represents stomach and intestines, G represents gills, H represents skin, I represents gallbladder, J represents scales, K represents muscle, and L represents gonads. Detailed Implementation

[0010] The technical solution of the present invention will be further studied through the following embodiments, but the scope of protection of the present invention is not limited in any way by the embodiments.

[0011] Example 1

[0012] 1. Experimental Animals: A total of 211 tilapia were used in this experiment. The Nile tilapia used in the experiment were provided by the Xiaotangshan Breeding Center of the Beijing Fisheries Research Institute. The fish were temporarily held in eight recirculating aquaculture systems with a volume of 1.5m × 1.5m × 1.0m, with continuous aeration for 24 hours, natural lighting, and 1 / 3 of the water changed every 2 days. The water temperature of the aquaculture system was controlled at 28±0.5℃, pH at 8±0.6, and dissolved oxygen at 6.5±1 or higher. To control for weight variation errors caused by long-term temporary holding, fish were obtained in batches and placed in the temporary holding tanks for the experiment, with each batch held for 7–14 days. During the temporary holding period, the fish were fed once a day at 8:00 AM (purchased from Tangshan Youyi Jingzheng Feed Co., Ltd.), with a feed amount of 0.5% of the fish's body weight. The health status of the fish was observed, and unhealthy fish were discarded. Feeding was stopped two days before the experiment to allow the gastrointestinal tract to empty.

[0013] 2. Experimental Design: This embodiment focuses on 12 tissues or organs of tilapia, including blood, heart, liver, kidneys, spleen, intestines, gills, skin, gallbladder, scales, muscles, and gonads. Preliminary dissection experiments showed that if the tilapia weighed less than 20g, the weight of blood, kidneys, intestines, scales, muscles, and gonads could not be completely separated and accurately measured. To obtain accurate values ​​covering the weights of tissues and organs in tilapia of different sizes, this embodiment artificially divided tilapia weighing 20-900g into six weight ranges: 20-50g, 50-100g, 100-300g, 300-500g, 500-700g, and 700-900g. Each range had a sample size of at least 30 fish, and the number of juvenile fish was increased to reduce the impact of operational errors. A total of 211 fish were dissected, and their weights and tissue / organ weights were obtained. Data from 201 fish (weighing 20-900g) were used for regression analysis. Eight fish weighing between 20 and 900g, plus two fish weighing 3.66g and 954.22g respectively, were randomly selected to verify the accuracy of the regression equation prediction.

[0014] 3. Measurement methods: The specific methods for collecting data from each tissue and organ are as follows:

[0015] Blood: The blood weight is the maximum amount that can be drawn from the tail vein. Using a 1ml syringe, first draw blood from the middle of the caudal peduncle, about one scale below the lateral line scale. After drawing blood from this position until no more blood is drawn, move forward about two scales along the lateral line scale and draw blood from 3 to 4 positions per fish, drawing as much blood as possible, and then weigh it.

[0016] Heart: The heart is composed of the ventricles, auricles, and white bulbar arteries.

[0017] Liver: The liver is located near the front of the esophagus, and its shape is similar to a dumbbell, with the front end being significantly larger than the back end.

[0018] Kidneys: Cut open the septum between the abdominal cavity and the spine, remove the white connective tissue that protects the kidneys, and the red kidneys are attached to the abdominal edge of the spine.

[0019] Spleen: The spleen is long and thin, and dark red in color.

[0020] Gastrointestinal tract: This includes the intestines and the stomach. The stomach is cut open using dissecting scissors, and any remaining contents from the stomach and intestines are emptied using forceps before weighing.

[0021] Gills: The total weight of both gills. A complete gill on each side consists of four gill arches, as well as corresponding gill rakers and gill filaments.

[0022] Skin: All the skin on the fish's body and tail, except for the fins and head.

[0023] Gallbladder: During separation, first use forceps to clamp the bile duct where the gallbladder connects to the liver to prevent bile leakage, then completely separate the gallbladder and weigh it.

[0024] Scales: The weight of the scales is determined by measuring the difference in weight of the fish before and after the scales are removed, using an indirect measurement method.

[0025] Muscles: Muscle weight was measured in two steps. First, the muscles of the trunk, tail, and lower part of the head (neck) were dissected and recorded as W1. Then, the mixed muscle and skeletal tissue after dissection of the trunk and tail was weighed and recorded as W2. After heating the mixed tissue in boiling water for 3-5 minutes, all muscles were removed, and the weight of the remaining skeleton was recorded as W3. Muscle weight W = W1 + (W2 - W3).

[0026] Gonads: The gonads were isolated, weighed, and their developmental stages were recorded.

[0027] Remaining tissues: mainly fish head, fins, cooked fish bones (W3 from the muscle), abdominal fat, and removed connective tissue, etc. Used to help calculate the recovery rate of dissection procedures.

[0028] Blood, heart, liver, kidneys, spleen, intestines, gills, skin, gallbladder, gonads, and muscles were weighed using an analytical balance (accuracy 0.0001 g). Scales, fish weight, and remaining tissues were weighed using an electronic balance (accuracy 0.01 g). The dissection recovery rate was the ratio of the total weight of blood, heart, liver, kidneys, spleen, intestines, gills, skin, gallbladder, scales, muscles, gonads, and remaining tissues to the fish's body weight.

[0029] 4. Data Analysis: SPSS software was used for data analysis. First, Spearman correlation coefficient was used to analyze the correlation between the weight of each tissue and organ and body weight. Then, the curve estimation function of SPSS software was used to perform regression analysis on the overall data and the segmented data respectively.

[0030] Regression analysis of the overall data used all data from 201 fish. Curve estimation was performed using scatter plots and 10 commonly used regression models (power function, cubic function, linear function, quadratic function, s-curve, logarithmic curve, composite curve, exponential curve, growth curve, and inverse function), and analyzed using R... 2 The optimal regression model was determined using the Coefficient of Determination, and the optimal regression equation was established. The mathematical formulas for the 10 regression models are shown in Table 1. The predicted weights of tissues and organs from 10 fish with body weights ranging from 3.66 to 954.22 g were calculated using the regression equations. The results were then analyzed using the δ value (Relative error) and R². 2 The values ​​are used to verify the prediction effect.

[0031]

[0032]

[0033] i represents the i-th sample. Represents the predicted value, y i This represents the measured value. This represents the average value of the measured values.

[0034] The segmented data involved dividing the 201 fish into three groups based on their weight: small fish (20-100g, sample size 74 fish), medium fish (100-600g, sample size 81 fish), and large fish (600-900g, sample size 46 fish). Regression analysis was then performed on each of the three groups separately. The regression analysis method for the segmented data was the same as that for the overall data, and the predictive effectiveness of the regression equations was verified. Finally, the results of the segmented data were compared and analyzed with those of the overall data.

[0035] Table 1 shows the regression models and corresponding formulas used for curve estimation.

[0036]

[0037] 4. Results

[0038] Table 2 shows the sample size and anatomical recovery rate of the 201 tilapia used in the regression analysis for each weight range. As can be seen from Table 2, the weight of the 201 tilapia used in this study was relatively evenly distributed within the range of 20-900g, and the overall anatomical loss rate was between 0.99% and 10.51%, indicating relatively low anatomical loss.

[0039] Table 2. Sample size and dissection recovery rate of 201 tilapia in different weight ranges.

[0040]

[0041] Note: Recovery rate, dissection recovery rate, and the ratio of the sum of the weights of the parts after dissection to the fish's weight before dissection.

[0042] Correlation analysis of the overall data from 201 fish showed that there were highly significant correlations (P < 0.001) between the weight of each tissue and organ and the body weight, and all of these correlations were highly significant positive. The correlation coefficients are shown in Table 3. Among them, the correlation coefficient of the spleen was relatively low, ρ = 0.865 < 0.9, where ρ is the Spearman correlation coefficient.

[0043] Table 3. Correlation coefficients between the weight of various tissues and organs and body weight.

[0044]

[0045] Note: ρ is the Spearman correlation coefficient.

[0046] Using data from 201 fish, regression analysis was performed on body weight for each tissue and organ. The R-squared values ​​of each regression model were calculated. 2 The values ​​are shown in Table 4. Among all tissues and organs, R... 2 The regression models with the largest values ​​are all power functions. Except for the gonads (where Ri is a power function). 2 Apart from a value of 0.897, the power function model R for other tissues and organs 2 The values ​​were all greater than 0.9, and the R values ​​for skin and muscle were... 2 The value is even greater than 0.99. Power function regression equations were established with body weight as the independent variable and the weight of each tissue / organ as the dependent variable: y 血 =0.0828x 0.771 y 心 =0.00160x 0.951 y 肝 =0.0280x 0.872 y 肾 =0.00387x 0.820 y 脾 =0.00167x 0.972 y 肠胃 =0.0511x 0.808 y 鳃 =0.0556x 0.911 y 皮肤 =0.0152x 1.122 y 胆囊 =0.00730x 1.060 y 鳞 =0.0749x 0.865 y 肌肉 =0.353x 1.053 y 生殖腺 =0.000393x 1.202The power function equation curve and scatter plot of body weight versus the weight of various tissues and organs are shown in [reference needed]. Figure 1 .

[0047] The power function equations derived from the overall data were used to predict the organ weights of 10 tilapia weighing between 3.66 and 954.22 g. The power function equations, relative errors (predicted weight compared to measured values), and Rw for each organ weight were also analyzed. 2 The values ​​(power function equation for 10 fish) are shown in Table 5. As shown in Table 5, the average relative error of the regression equation for predicting the weight of blood, heart, kidneys, intestines, gills, skin, gallbladder, scales, and muscles of 10 fish ranged from -17.68% to 16.82%, all showing good predictive performance. The relative error range of the regression equation for predicting the weight of liver, spleen, and gonads of 10 fish was -32.22% to 118.01%, -92.94% to 80.90%, and -81.66% to 4.20%, respectively, showing relatively poor predictive performance.

[0048] Table 4. R-squared values ​​of 10 regression models for the relationship between the weight of various tissues and organs and body weight in the overall data regression analysis. 2 value

[0049]

[0050] Note: All regression models in the table are statistically significant in the analysis of variance.

[0051] Table 5 shows the power function equations obtained from the overall data regression analysis and their R-squared values ​​for predicting the weights of 10 tilapia ranging from 3.66 to 954.22 g. 2 Value and δ value

[0052]

[0053]

[0054] Note: δ, relative error, is the difference between the predicted value and the measured value divided by the measured value, expressed as the mean ± standard deviation of 10 fish. R 2 The coefficient of determination is calculated by substituting the predicted and measured weights of various tissues and organs from 10 fish into the formula. y represents the weight of the tissue or organ, and x represents the body weight of the fish.

[0055] The weight ranges for the three groups of data were 20-100g (small fish group), 100-600g (medium fish group), and 600-900g (large fish group), with a sample size of more than 45 fish in each group. Due to collinearity among model terms during curve estimation, cubic functions were not used as regression models for the gonads of the medium fish group and all organs of the large fish group. When estimating the curves for the gallbladder and gonads of the large fish group, none of the regression models showed statistical significance (p > 0.05 in the ANOVA table), so the regression equation was... (Predicted values ​​equal sample averages), the calculated average weight of the gallbladder is 7.7200g, and the average weight of the gonads is 0.5783g. Due to the overall data analysis results, the R values ​​for all tissues and organs... 2 Since the maximum regression models are all power functions, power function equations and R-squared values ​​were established for each tissue and organ in the three-part segmented data. 2 The maximum regression model equations were all validated for predictive effectiveness.

[0056] Piecewise fitting of 3 sets of data, power function equations and R0 for each tissue and organ. 2 The maximum regression model equations are shown in Table 6, and the prediction results for the organ weights of 10 tilapia weighing 3.66–954.22 g are shown in Table 7. As shown in Table 6, the R values ​​for different organs within the same group and the same organ in different groups are shown in the three data sets. 2 The maximum regression models all showed differences. As shown in Tables 6 and 7, regression analysis was performed on the three-part data sets, and the resulting R values ​​were... 2 The maximum regression model types include power function, quadratic function, cubic function, inverse function, and S-curve models. Among them, the predictive performance of non-power function model equations is lower than that of power function equations fitted with the same data.

[0057] Regression analysis of both the overall data and segmented data was performed using R. 2 The maximum value was used as the criterion for determining the optimal regression model type, and then the regression equation was established and the predictive effect was judged. The results showed that the weight of each tissue and organ of Nile tilapia was related to the body weight as a power function, and the optimal regression equation is shown in Table 5, with relatively accurate predictive effect. Table 6.3 shows the R-values ​​of the weight of each tissue and organ of tilapia to the body weight obtained from the regression analysis of the segmented data in Group 3. 2 The regression model equation and the power function equation when the value is maximized

[0058]

[0059] Note: When performing regression analysis on the gallbladder and gonads of the large fish group, since all regression models were not statistically significant (P > 0.05), the organ weight was equal to the sample mean. The gallbladder weight was 7.7200g, and the gonad weight was 0.5783g; power function equation; "-" indicates R0.2 The maximum regression model is a power function model; y represents the weight of the tissue or organ; x represents the weight of the fish.

[0060] Table 7.3 shows the R-values ​​obtained from the regression analysis of the segmented data. 2 The relative error and R0 of the maximum regression model equation and the power function equation for predicting the weight of 10 tilapia ranging from 3.66 to 954.22 g were compared. 2

[0061]

[0062] Note: When performing regression analysis on the gallbladder and gonads of the large fish group, the prediction results are not listed because all regression models were not statistically significant (P > 0.05); δ, relative error, is the difference between the predicted and measured values ​​divided by the measured value, expressed as the mean ± standard deviation of 10 fish; R 2 The coefficient of determination (R) is obtained by substituting the predicted and measured weights of various tissues and organs from 10 fish into the formula; "-" indicates the maximum R. 2 The regression model is a power function model.

Claims

1. A method for estimating the weight of organs in healthy tilapia, characterized in that, The method is as follows: Measure the tilapia's current body weight and calculate the weight of blood, heart, kidneys, stomach and intestines, gills, skin, gallbladder, scales, muscles, and gonads according to the following formula; the formula for calculating blood is y = 0.0828x. 0.771 The formula for calculating the heart's diameter is y = 0.00160x. 0.951 The formula for calculating the liver is y = 0.0280x. 0.872 The formula for calculating the kidney is y = 0.00387x. 0.820 The formula for calculating the spleen is y = 0.00167x. 0.972 The formula for calculating gastrointestinal function is y = 0.0511x. 0.808 The formula for calculating gills is y = 0.0556x. 0.911 The formula for calculating skin thickness is y = 0.0152x. 1.122 The formula for calculating the gallbladder size is y = 0.00730x. 1.060 The formula for calculating the scale size is y = 0.0749x. 0.865 The formula for calculating muscle mass is y = 0.353x. 1.053 The formula for calculating the gonads is y = 0.000393x 1.202 , where x is body weight and y is the weight of each organ.

2. A method for evaluating the experimental effect of tilapia, wherein the method comprises measuring the weight of tilapia at each stage of the experiment, evaluating the organ weight of healthy tilapia at that weight using the method described in claim 1, obtaining the weight of the experimental tilapia organs, and evaluating the influence of experimental factors on the various organs of tilapia based on the obtained organ weight of healthy tilapia at that weight.

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