Since no readily available equipment or technical solution for determination of shrimp gut pH existed, we developed it by ourselves as follows: frozen shrimp were thawed in room temperature within one hour, and the gut was removed using needles and placed in an Eppendorf tube (1.5 mL). An aliquot (0.2 mL) of sterilized seawater was added to the tube, the gut was homogenized by hand with a glass rod, and the pH of the homogenate was measured with pH test paper (EMD Millipore Corporation, Darmstadt, Germany). Then, another aliquot of seawater was added to the homogenate, and the pH was again determined after mixing. This process was repeated until a total of 1 mL of seawater had been added to the homogenate. Finally, the pH values were plotted against the amount of seawater added, and a line of best fit was added to the data. The approximate pH values in the shrimp gut were then estimated by extrapolation back to the y-axis.
Here, two experiments were conducted. In the first, two shrimps reared on standard diet and two shrimps reared on feed supplemented with 5% (w/w) PHBH were used after the end of the 6-week feeding experiment (seeSection 2.5 ). In the second, 20 shrimps of various sizes reared on standard diet were used.
Here, two experiments were conducted. In the first, two shrimps reared on standard diet and two shrimps reared on feed supplemented with 5% (w/w) PHBH were used after the end of the 6-week feeding experiment (see