What is the difference between toxin binder and mold inhibitor?
They are two completely different things.
Toxin binder is actually binding the toxins after they are produced, similar to putting a plaster on a wound.
Mold inhibitor prevents the toxins from forming. It prevents the molds from becoming active and prevents them from producing micro toxins.
One important fact shown by research is that there can be high challenge of micro toxins, even if you don't have a clearly moldy raw material. This is because micro toxins exist in the field.
How can we measure the oxidation stability in the fish meal?
There are classic parameters (like oxy test or oxy bomb) that can be used to prove the oxidation status. For fish meal, the best way is to check the self-heating stability. Our recommendation is to run a real stability test, that will indicate what will happen on fish meal over the storage time. You can combine oxidation and nutritional parameter tests because oxidation always has an impact on nutrition, so such evaluation can cover full scale.
How to improve starch gelatinization in the pelleting process?
Moisture and temperature are prerequisite factors to control gelatinization.
It depends on the type of starch but as general rule it's better with comparatively higher moisture and temperature.
In relation to the antinutritional factors, would you recommend using phytase or xylanase for aqua diets?
It depends on your conditions. Phytase and xylanase are widely used for antinutritional factor issues, especially phytase that has good contribution to the availability of phosphorus and reduce environmental impacts in the end.
Can lysolecithins play a role in fat digestion in fish diets? Are there differences between species in this kind of approach?
Lysolecithin is widely applied because it's really good bio emulsifier and plays a very big important role in diet with high fat content. It's widely implied and it works very well in both fish and shrimp feed.
What is the optimal of the safe water activity level to prevent moldy?
It's relatively safe to be below 0.72; in addition, uniformity of humidity is also very important because mold can start at some certain area due to condensed water especially when feed is packed in warm.
What are the reasons to have many fines particles in sinking feed?
If there're too many fines in your sinking, the product might be too hard. One possible solution is raising the moisture level and making sure moisture is uniform, then check effect; also check your knives to make sure they are in good condition.
How to stop the oil leaking from floating pellets?
It has been observed in high fat feeds on storage or after few days of production. If it is floating, you can increase your expansion in order to release and stretch those molecules within the starches, that allows the actual product to absorb oil better.
Can water stability affect the product digestibility in fish?
The only direct relation is that if you have too low water stability there is a good chance that your starch is not gelatinized properly, while starch gelatinization is related to digestibility.
In shrimp feed do you recommend soft pellets or hard pellets?
The feed consumption of the shrimps is correlated with three physical factors of the wet pellet hardness, pellet water absorption or water absorption index (WAI) and pellet dry matter loss. Pellet water absorption and pellet dry matter loss were directly proportional to the consumption of feed by shrimps, and wet pellet hardness was found to be inversely proportional to shrimp feed consumption rate.
Does fat coating on feed reduce its floating? If yes, then how can we control it?
Ideally if you are creating a floating type of product, you can decrease the fat levels on the surface in form of coating; as oil delays the expansion of feed, and expansion is key for floating feed.
What is the factor involved in absorption of liquid (during coating) for a big size feed (e.g. > 15 mm)?
If it is a very large product, it may need more time to absorb the liquid, depending on the size of the product and whether it's a screw or drum or vacuum coating.
What are the strategies operators should follow to improve the pellet's physical properties like uniform size, smooth cutting, avoiding broken or shape-out pellets, avoiding sinking pellets or pellets with differential bulk densities?
It is essential to ensure that your grind and grist is uniform and optimum, but also ensure that the knives are sharp, because fragments and fines can be created if the lines are blunt.
In addition, an equally uniform moisture across the product is needed to make sure systems within the process are consistent.
Uniformity and consistency is the key thing for extrusion. Because the process is quite intense, it is preferred to ensure that parameters remain static, which has a direct implication on the final product.
Does retrogradation happen in feeds after extruder or pelleting?
The process of retrogradation refers to the realignment of the amylose and amylopectin molecules after gelatinization of the starch when the temperature of the pellets goes down. In principle, it happens in both extrusion and pelletizing of feed. However, the gelatinization in extrusion is usually more complete than in pelletization but the physicochemical process is the same.
Is there any difference between cooking using specific mechanical energy and thermal energy, talking about nutritional results?
Thermal energy is better than mechanical energy as this helps in better gelatinization and better cooking of feed. Thermal energy has less weight inside the barrel compared to using Specific mechanical energy (SME). Thus, thermal energy is advised for extruded feed.
If you have pre-gelatinized starch added to the process, could you avoid the pre-conditioning stage?
You can avoid that stage, but there is a risk as you might not get correct level of cook if you are using pre-gelatinized product and not get the required level of gelatinization in the finished feed. More thermal energy and mechanical energy in barrel can help in achieving better gelatinization together with moisture levels.
What is your opinion about included krill in aquafeed?
Krill has a fantastic attractability for shrimp; but as a protein source it is quite expensive. Also, there are a lot of claims and investigations that krill has health promoting activities that help the immune system.
It is applied under serious quantities for attractability, such as 3% in shrimp diet. It is useful and may be more useful if we have more scientific data on its on its health benefits.
What is a suitable protein source for aquaculture that can be used to replace fish meal?
It is replacing nutrients instead of replacing fish meal in diets. There is a lot of existing and novel protein concentrates, such as poultry by-product meal with high digestibility and nice acid amino profile, bacteria protein with good sustainability concept, and rapeseed and rice concentrate.
Suitability depends on the specific situation, including type of species, required kind and level of nutrients, regulation, material availability, and cost.
Which starch source is better for better quality of feed? Corn? Wheat? Rice?
Wheat has been shown to have the highest apparent digestibility index (ADI) in L. vannamei and is shown to have the highest water stability index (WSI) compared to other types of starch like corn, potato and sorghum.