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preface
Bighead carp is one of the four traditional big fish in the mainland, commonly known as silver carp, fat head, big head fish, etc., its head is large and fat, the flesh is snow-white and tender, and it is favored by consumers.
However, this culture mode based on natural food intake has led to long growth cycles and low yields of bighead carp, which is far from meeting market demand, so the development of high-quality bighead carp feed is urgent.
To alleviate this situation, the feed industry has begun to explore the addition of citric acid to bighead carp feeds in hopes of improving the growth performance and body composition of fish.
Today, Xiao Wang will learn with you about the effects of adding a certain level of citric acid to the feed on the growth performance and body composition of bighead carp.
Study on the potential and effect of citric acid in bighead carp culture
Acidifiers are a new type of feed additive that has attracted much attention because of its many advantages, including being easily absorbed by farmed animals, not polluting the breeding environment, and leaving no drug residues.
Among them, citric acid has been widely used in feed because of its unique flavor and excellent buffering ability.
To understand the effect of citric acid on bighead carp growth and body composition, we conducted an experiment in which we purchased seed bighead carp and fed a basal diet at the farm for 1 to 4 weeks to acclimatize to the environment.
We selected 720 healthy test fish with similar initial weight and randomly divided into 4 groups with 3 replicates each, each containing 60 fish.
The fish were placed in 12 test cages measuring 5 m × 5 m × 2.5 m in size, which were placed in an 8-acre pond at a depth of 4 m for a 60-day trial.
In the experiment, we added different proportions of citric acid to the feed, 0% (as a control group), 0.1%, 0.2% and 0.3% of the test diet.
We have developed our own diet, with fishmeal, casein and soybean meal as the main protein sources, soybean oil as the main fat source, protein content of 34.23%, crude fat content of 8.03%, moisture content of 10%.
During the trial, we used the cage culture mode, with a trough in the center of the cage, the water temperature was maintained at (27±2) °C, the pH value was maintained at 7.0±0.4, and the dissolved oxygen concentration in the water was greater than 5 mg/L.
We feed regularly 3 times a day, at 8:30, 13:00 and 17:30, and collect and dry the remaining feed 30 minutes after each feeding.
We also recorded feed feeding and observed the health of bighead carp every day, and carried out routine insecticidal and sterilization treatment every half month.
After the trial, we performed a series of measurements, first starving the test fish for 12 hours, then weighing them accurately and calculating metrics such as weight gain, specific growth rates, and food coefficients.
We also randomly selected 10 bighead carp for each replicate, measured their weight, body length, and head length, and isolated and weighed the internal organs to calculate fertility, visceral body ratio, and liver-to-body ratio.
Finally, we randomly selected 5 bighead carp from each cage, wiped their surface moisture, weighed, sheared, aliquoted and dried, and the samples were crushed and stored in a -20°C freezer for further testing.
In terms of data analysis, we performed one-way ANOVA using SPSS 19.0 software and multiple comparisons using Duncan's test method, and the results were expressed as "mean ± standard error" with a significance difference level of P<0.05.
So, what conclusions can we draw from this? What is the effect of citric acid in bighead carp farming?
Effect of citric acid on growth performance of bighead carp
Trials have found that the addition of citric acid to fish feed has a significant effect on bighead carp growth, and as the level of citric acid addition increases, bighead carp growth shows an interesting trend of growing first and then stabilizing.
At the same time, the utilization efficiency of the bait showed a similar trend, that is, it first decreased, then remained stable, specifically, when the citric acid addition level was less than 0.2%, the growth rate and specific growth rate of bighead carp continued to increase as the amount of addition increased.
These two parameters reached their highest values when the citric acid addition level reached 0.2%, and the growth performance of bighead carp remained relatively stable despite a further increase in the citric acid addition level.
At the same time, the increase in the level of citric acid addition in the feed seemed to have a certain effect on the fertility of bighead carp, but the difference between the groups was not significant.
As the level of citric acid added in the feed increases, the crude ash content of bighead carp shows an interesting trend, that is, it first remains stable and then decreases.
When the level of citric acid addition in feed is less than 0.2%, the crude ash content of bighead carp remains stable, but when the citric acid addition level is higher than 0.2%, the crude ash content of bighead carp begins to decrease significantly.
These findings provide important information on the addition of citric acid to feed for bighead carp culture, which is expected to be applied in practical culture.
Citric acid, a common organic acid, undoubtedly has an important impact on improving the growth performance of bighead carp, and we can visually assess the growth of fish through weight gain rate and specific growth rate.
We found that adding 0.21% citric acid to the feed significantly increased the weight gain rate and specific growth rates of grass carp.
Similarly, adding 0.3% citric acid to tilapia feed is also effective in increasing its specific growth rate, while our experimental studies have shown that adding 0.2% citric acid to bighead carp feed can achieve the optimal level of bighead carp weight gain rate and specific growth rate.
In addition to the rate of gain and specific growth rates, the feed factor is also an important indicator to evaluate the efficiency of feed utilization.
Our results also consistently show that when 0.2% citric acid is added to the feed, bighead carp has the lowest feeding factor.
So, how does citric acid work? This is because citric acid has a sour taste that can directly stimulate the taste perception system of bighead carp and improve the taste of the feed, thereby promoting the appetite of bighead carp and increasing its food intake.
And citric acid can reduce the pH of feed, thereby improving the intestinal environment of bighead carp, promoting the activity of its digestive enzymes, free citric acid is part of the biological tricarboxylic acid cycle, can provide a nutritional source of protein for bighead carp, and the appropriate amount of citric acid can reduce the body's consumption of protein.
Therefore, it may have many effects on the growth performance of bighead carp, including growth rate, feed intake and digestion, and energy use.
Citric acid can promote feed intake and digestion by increasing the appetite and digestive enzyme activity of bighead carp, and feed with citric acid can increase the food intake of bighead carp and significantly increase the activity of gastrointestinal enzymes, which helps to improve the digestion and absorption of nutrients in feed by bighead carp.
Moreover, the presence of citric acid in feed can improve the glucose metabolism of bighead carp and increase the oxidation degree of fish body fat, thereby improving energy utilization efficiency and growth performance.
So, in addition to having a certain impact on the growth performance of bighead carp, what is the impact on the shape index and body composition of the fish?
Effect of citric acid on bighead carp body composition
The health and growth of bighead carp can be evaluated by indicators such as fertility, which is one of the important indicators.
In general, the higher the fertility, the better the body shape and faster the growth rate of bighead carp, and the liver-to-body ratio is also an important parameter, which indicates the degree of fat deposition in the liver of bighead carp, and also reflects the utilization rate of fat by bighead carp.
In the above experiments, we did not find that the addition of citric acid to bighead carp feed did not appear to cause significant changes, specifically, the parameters of fertility, liver-to-body ratio, and visceral body ratio did not change significantly after being affected by citric acid.
Although citric acid is added to the feed, it does not appear to have a significant effect on physical characteristics such as bighead carp growth and fat metabolism.
After ingesting foods related to citric acid, fish will use the absorbed nutrients for metabolic activities necessary to maintain life, and will also store these nutrients in the form of proteins and fats as their own tissues, especially for the increase in crude protein levels, which will promote growth and development.
We found that adding 0.2% citric acid to the feed significantly increased the crude protein content in bighead carp.
In addition to crude protein levels, the addition of citric acid to feed had no significant effect on crude fat and ash content in bighead carp.
However, for crude fat and ash content, the addition of citric acid did not cause significant changes, and the exact mechanism of citric acid on the composition of fish still needs further research.
In short, the effect of adding citric acid to feed on the body composition of bighead carp is self-evident, after all, citric acid has the effect of increasing protein content and muscle mass, reducing fat content, improving fatty acid composition quality and increasing mineral content.
These effects help to improve the nutritional quality, edible value and market competitiveness of bighead carp.
epilogue
It should be pointed out that the effect of citric acid addition may be affected by some factors, such as the level of addition, feeding conditions and environmental factors.
Therefore, for best results, breeders should determine the appropriate level of citric acid addition based on specific circumstances and scientific advice.
By optimizing the level of addition and the culture conditions, this feed additive can be better used to meet the market demand and increase the production of bighead carp, while maintaining a good balance of fish components, which is of great significance for improving the culture mode of bighead carp and improving the breeding efficiency.