Mandarin fish recirculating aquaculture accurate feeding method based on gastrointestinal emptying parameters

Abstract

The invention relates to a precise feeding method for mandarin fish recirculating aquaculture based on gastrointestinal emptying parameters, and belongs to the technical field of aquaculture engineering, and the mandarin fish culture conditions are as follows: the water temperature is 25 + / -1.0 DEG C, the dissolved oxygen is greater than or equal to 7.0 mg / L, the pH is 7.8 + / -0.3, the salinity is less than or equal to 0.5, the nitrite is less than or equal to 0.05 mg / L, the ammonia nitrogen is less than or equal to 0.15 mg / L, and the illumination period is 12L: 12D. The crude protein of the special compound feed for mandarin fish is greater than or equal to 48%, the crude fat is greater than or equal to 10% (Guangdong Jiabig Feed Co., Ltd), the daily feeding amount is 2.5% of the body weight of the mandarin fish, and the feeding frequency is four times per day. According to the breeding method, the weight gain rate, the specific growth rate and the survival rate of the mandarin fish reach the highest level, and the feed coefficient is the lowest.

Description

Technical Field

[0001] The invention belongs to the technical field of aquaculture engineering, and in particular relates to a precise feeding method for mandarin fish in circulating aquaculture based on gastrointestinal emptying parameters. Background Art

[0002] As a freshwater fish with high economic value in my country, the annual aquaculture output of mandarin fish continues to grow, but the traditional aquaculture model has significant defects. Currently, mandarin fish aquaculture mostly adopts an empirical feeding strategy, which does not take into account the digestive physiological characteristics of fish, resulting in low feed conversion rate, residual bait polluting water quality, increased aquaculture costs and disease risks. At the same time, due to the mismatch between feeding time and the gastrointestinal emptying cycle of mandarin fish, the aquaculture survival rate is generally low, which seriously restricts the development of the industry. Existing automatic feeding equipment can only achieve timed and quantitative feeding, and lacks the function of dynamic adjustment according to the physiological state of fish. Although it is known that the gastrointestinal emptying rate of fish is affected by factors such as food type, feeding frequency, and water temperature, there is insufficient research on the gastrointestinal emptying rules of mandarin fish, especially in the large-sized seedling stage, and there is no technical solution to convert gastrointestinal emptying parameters into practical and precise feeding. An innovative aquaculture method and system are urgently needed to solve the above problems. Summary of the Invention

[0003] In response to the above-mentioned existing technologies, the present invention provides a precise feeding method for recirculating aquaculture of mandarin fish based on gastrointestinal emptying parameters. The method formulates a precise feeding frequency according to the gastrointestinal emptying parameters of mandarin fish, which on the one hand reduces the feed coefficient and on the other hand increases the growth rate of mandarin fish.

[0004] The present invention is achieved through the following technical solutions:

[0005] A precision feeding method for recirculating aquaculture of mandarin fish (Siniperca chuatsi) based on gastrointestinal emptying parameters was developed. Mandarin fish culture conditions include: water temperature of 25±1.0°C, dissolved oxygen ≥7.0 mg / L, pH 7.8±0.3, salinity ≤0.5, nitrite ≤0.05 mg / L, ammonia nitrogen ≤0.15 mg / L, and a photoperiod of 12 L:12 D. Mandarin fish feed is formulated with a crude protein content of ≥48% and a crude fat content of ≥10%. The daily feed intake is 2.5% of the fish's body weight, and the fish are fed four times a day.

[0006] Furthermore, the feeding time points are 06:00, 10:00, 14:00, and 18:00 every day.

[0007] The beneficial effects of the present invention compared with the prior art are as follows:

[0008] The culture conditions of the mandarin fish according to the present invention are as follows: water temperature of 25±1.0°C, dissolved oxygen ≥7.0 mg / L, pH 7.8±0.3, salinity ≤0.5, nitrite ≤0.05 mg / L, ammonia nitrogen ≤0.15 mg / L, and a photoperiod of 12 L:12 D. The mandarin fish is fed a special formula feed containing ≥48% crude protein and ≥10% crude fat, with a daily feeding amount of 2.5% of the fish's body weight, divided equally into four feedings. The mandarin fish cultured according to the present invention achieves the highest weight gain rate, specific growth rate, and survival rate, and the lowest feed coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Effects of different feeding frequencies on the instantaneous digestion rate of bait in the stomach of mandarin fish;

[0010] Figure 2 Gastric emptying rate model of mandarin fish under different feeding frequency conditions;

[0011] Figure 3 Effects of different feeding frequencies on intestinal filling and emptying in mandarin fish;

[0012] Figure 4 .Intestinal filling and emptying model of mandarin fish under different feeding frequency conditions. DETAILED DESCRIPTION

[0013] The present invention will be further described below in conjunction with the examples. However, the scope of the present invention is not limited to the following examples. Those skilled in the art will appreciate that various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention.

[0014] Example 1

[0015] 1 Experimental fish

[0016] Mandarin fish (Siniperca chuatsi) were purchased from a national aquatic breeding farm in Yangzhou, Jiangsu Province. A total of 2,400 healthy, uniform, large-sized fingerlings (33.78 ± 2.47 g) were selected and temporarily maintained in four small-scale recirculating water systems (each containing six 1.5 m³ circular tanks). Water quality in the recirculating water system was strictly controlled: temperature 25 ± 1.0°C, dissolved oxygen ≥ 7.0 mg / L, pH 7.8 ± 0.3, salinity ≤ 0.5, nitrite ≤ 0.05 mg / L, ammonia nitrogen ≤ 0.15 mg / L, and a photoperiod of 12 L:12 D. During the temporary period, the fish were fed a specially formulated diet for mandarin fish (crude protein ≥ 48%, crude fat ≥ 10%, produced by Guangdong Jieda Feed Co., Ltd.) at a daily feed rate of 2.5% of their body weight. Any remaining feed and feces were removed 30 minutes after feeding. After 7 days of temporary maintenance, healthy individuals were selected for the full experiment.

[0017] 2 Experimental design

[0018] Four feeding frequency groups were set up: continuous feeding (06:00-18:00), twice daily (06:00 and 18:00), four times daily (06:00, 10:00, 14:00, and 18:00), and six times daily (06:00, 08:24, 10:48, 13:12, 15:36, and 18:00). Each group had three replicates, and 100 fish were placed in each tank. The experiment lasted 60 days, with fish fed daily at 2.5% of their body weight. The amount fed each time was the daily feeding amount divided by the number of feedings. Leftover bait was collected and recorded promptly.

[0019] 3 Data collection and measurement

[0020] 3.1 Growth index determination

[0021] After the experiment, the total length (TL), body length (SL), body weight (BW), visceral weight (VW), and liver weight (LW) of the fish were measured, and the survival rate (Survival), absolute growth rate (AGR), feed conversion ratio (FCR), fatness (CF), liver-to-body ratio (HSI), and visceral-to-body ratio (VSI) were calculated.

[0022] Determination of growth index:

[0023] Survival rate = 100 × final number of fish / initial number of fish;

[0024] Absolute growth rate (SGR) = 100 × (ln final weight – ln initial weight) / culture time;

[0025] Feed conversion ratio (FCR) = feed consumed / weight gained;

[0026] Fat content (CF) = (W / L 3 )×100;

[0027] Liver index (HIS,%) = (liver weight / total fish weight) × 100;

[0028] Viscera-to-body ratio (VSI, %) = (viscera weight / total fish weight) × 100;

[0029] 3.2 Gastrointestinal emptying parameter determination

[0030] After the experiment, mandarin fish that had been fasting for 24 h were fed with a full diet (until the feed sank to the bottom for 2 minutes without fish ingesting it). Samples were then taken at time points of 0, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, and 12 h. Five fish were taken from each group each time. After MS-222 anesthesia, the fish were dissected, and the gastrointestinal contents were separated and weighed (accurate to 0.1 mg). The relative gastrointestinal fullness (weight of gastrointestinal contents / weight of fish × 100%) was calculated.

[0031] 4 Data Processing

[0032] Intestinal emptying time was calculated as the time it took for the filling degree of the contents to drop to 50% of the peak value. Data statistical analysis was performed using SPSS 26.0. One-way analysis of variance (ANOVA) was used to compare the differences between the groups. P < 0.05 was considered significant. The model was fitted by SPSS software curve fitting and R was used. 2 The maximum value is the selection criterion.

[0033] 5 Results

[0034] 5.1 Effects of different feeding frequencies on the growth performance of mandarin fish

[0035] As shown in Table 1, the results showed that feeding frequency significantly affected the growth performance of mandarin fish fry after 60 days of culture. The four-times-a-day feeding group performed best, with the highest final body weight, weight gain rate, specific growth rate, and survival rate, and the lowest feed conversion ratio. The six-times-a-day feeding group was second best. The continuous feeding group had significantly lower final body weight, weight gain rate, specific growth rate, and survival rate than the other groups, and a significantly higher feed conversion ratio (P>0.05).

[0036] Regarding physiological indices, feeding frequency significantly affected the liver-to-body ratio (HSI) of mandarin fish. The HSI of the four- and six-times-a-day feeding groups was significantly higher than that of the continuous- and twice-a-day feeding groups (P<0.05), likely due to the increased metabolic burden on the liver under high-frequency feeding. However, different feeding frequencies had no significant effect on the visceral-to-body ratio (VSI) or fatness (CF) of mandarin fish.

[0037] Table 1 Effects of different feeding frequencies on the growth performance of mandarin fish

[0038]

[0039]

[0040] (2) Effects of different feeding frequencies on stomach filling and emptying in mandarin fish

[0041] Depend on Figure 1 We can see that there is no significant difference in the effect of different feeding frequencies on the instantaneous digestion rate of bait in the stomach of mandarin fish. The relative contents of the initial satiety of mandarin fish in each feeding group were 6.43±0.38, 6.77±0.28, 6.84±0.18 and 6.51±0.47, respectively. Basically, the relative contents in the stomach decreased significantly after 4 hours, reaching 3.35±0.13, 3.25±0.21, 3.29±0.16 and 3.45±0.19, respectively. After 10 hours, the relative contents of the remaining food in the stomach were basically digested, which were 0.47±0.08, 0.34±0.06, 0.36±0.03 and 0.47±0.06, respectively, and digestion was completed in 12 hours.

[0042] (3) Effects of different feeding frequencies on gastric emptying rate of mandarin fish

[0043] Depend on Figure 2 The gastric emptying rate patterns of mandarin fish at different feeding frequencies all conformed to a cubic equation, with no significant interaction between them. Furthermore, the amount of food in the stomach gradually decreased over time. Calculations based on the model revealed that the time to appetite recovery (50% gastric emptying) at different feeding frequencies at 25±1.0°C was 4.55±0.21, 4.31±0.14, 4.19±0.11, and 4.56±0.16 h, respectively. The time to complete appetite recovery (90% gastric emptying, essentially complete digestion) was 8.67±0.23, 8.43±0.52, 8.31±0.25, and 8.66±0.31 h, respectively. Under normal conditions, mandarin fish require approximately 4.40±0.16 h to digest approximately 50% of their gastric food after a full meal, and approximately 8.52±0.33 h to digest approximately 90% of their food.

[0044] (4) Effects of different feeding frequencies on the filling and emptying of the intestines of mandarin fish

[0045] Depend on Figure 3 It can be seen that the intestinal contents of each feeding group showed a three-stage characteristic change pattern: the intestinal filling degree increased in a temporal manner after feeding, reached a peak plateau 3-6 hours after satiety and maintained a high fullness state, and then entered the accelerated emptying stage. The emptying speed increased significantly from 6-10 hours, and the intestine was basically empty at the 12-hour node, indicating that intestinal filling and emptying were mainly dependent on physiological rhythms rather than driven by exogenous feeding frequency.

[0046] (5) Intestinal filling and emptying model of mandarin fish under different feeding frequencies

[0047] Depend on Figure 4 The results indicate that the intestinal filling and emptying function models of mandarin fish are consistent with cubic functions, and that different feeding frequencies have no significant effect on these patterns. As digestion time increases, the relative content of food in the mandarin fish intestine increases first and then decreases significantly. According to the model calculation, at 25±1.0°C, the time it took for the mandarin fish's intestine to be 50% filled was 1.35±0.56, 1.32±0.38, 1.28±0.48, 1.24±0.21, and 2.07±0.09 hours, respectively; the time it took for the intestine to be 50% empty was 7.77±0.94, 7.55±1.05, 7.70±1.21, and 7.15±1.07 hours, respectively; and the time the food spent in the intestine was 6.42±1.09, 6.23±1.12, 6.42±1.30, and 5.91±1.09 hours, respectively, with an average of 6.25±0.24 hours. This indicates that different feeding frequencies did not affect the filling, emptying, or residence time of the mandarin fish's intestine.

Claims

1. A precise feeding method for mandarin fish circulating aquaculture based on gastrointestinal emptying parameters, characterized in that: The breeding conditions of mandarin fish are as follows: water temperature 25±1.0℃, dissolved oxygen ≥7.0mg / L, pH 7.8±0.3, salinity ≤0.5, nitrite ≤0.05mg / L, ammonia nitrogen ≤0.15mg / L, photoperiod 12L:12D; the crude protein of mandarin fish is ≥48%, the crude fat is ≥10%, the daily feeding amount is 2.5% of the fish body weight, and the feeding frequency is four times / day.

2. The method according to claim 1, characterized in that The feeding time is 06:00, 10:00, 14:00 and 18:00 every day.

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