Microscopic. Hepatopancreas condition

HEPATOPANCREAS CONDITION

The condition and appearance of the hepatopancreas gives a good indication of the feeding state and condition of the PL. In starved animals, the hepatopancreas takes on a shrunken, pale appearance whereas in well- fed animals, the full and dark or coloured hepatopancreas is due to the feed ingested. If the hepatopancreas is shrunken, it indicates that the PL are underfed or are not actively feeding, neither of which is desirable for PL to be stocked in grow-out ponds. Other features to look for in the hepatopancreas are the presence of large numbers of digestive vacuoles giving the hepatopancreas and the foregut a “bubble”-like or turbid appearance. This indicates that the shrimp are both feeding and digesting well. The movement of the gut (peristalsis) should also be strong. In some cases, the hepatopancreas may appear dark. However, on closer inspection, it can be seen that it is full indigestible material. Digestive vacuoles are few and/or peristalsis is weak or absent. If the hepatopancreas is empty but not excessively shrunken, this may simply indicate that PL need to be fed or that there is not enough feed in the tank. In this case, a second sample can be taken one or two hours after feeding to see if the condition improves. Similarly, if the hepatopancreas is full but there are no digestive vacuoles present, this may indicate that the PL has only recently been fed.

• Good hepatopancreas condition. The hepatopancreas is full and easy to see. The colour of the hepatopancreas depenps upon the diet.

• Good hepatopancreas condition. The hepatopancreas is full and easy to see. The light colour to due to large concentrations of digestive vacuoles (sometimes referred to as “lipid vacuoles” or bubble) in the hepatopancreas cells indicating good digestion.

• Poor hepatopancreas condition. The hepatopancreas is empty an shrunken. This may indicate chronic underfeeding or starvation, or the presence of infection. Note the muscle condition is also poor.

• Poor hepatopancreas condition. The hepatopancreas is pale and difficult to see there is a cloudy / brown appearance which may indicate bacterial infection. At higher magnification, motile rods may be observed in squash mounts. Note that the absence of motile rods does not necessarily indicate no bacterial infection.
   

• Poor hepatopancreas condition. The hepatopancreas is full of dark mass of indigestible material. In most cases the PL will not be able to get rid of this and will die. The cause of this may be either nutritional or due to infection.

 

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