DOES K-DIFORMATE SUPPLEMENTATION IMPROVES GROWTH AND DIET STAIBLITY OF JUVENILE WHITE SHRIMP(LITOPENAEUS VANNAMEI)?

A study was conducted to investigate the effects of potassium diformate (K-diformate) supplementation in two protein levels on growth, food conversion and survival in juvenile white shrimp, litoppenaeusvannamei.Two dietary protein levels, 41% dietary protein(CP41) and 37% dietary protein(CP37) was formulated and supplemented of graded K-diformate levels 0%, 0.1%, 0.2%, 0.4%, 0.8%, 1.4% and 2.0%.Post larvae white shrimp (Litopenaeusvannamei) of initial mean weight 0.82Â±0.08g were randomly stocked in 45 aquarium tanks with a working volume of 50 L (60Ã—40Ã—30 cm ) at a stocking density of 10 shrimps per aquarium.The result of this study did not show significant difference in percentage weight gain and survival rate among shrimps fed CP41 and CP37 with graded K-diformate supplemented diet. No K-diformate dose response was observed at the end of the study. The results of present study proof that K-diformate supplemented diet do not affect water pH and feeding diet stability in water.


ISSN: 2320-5407
Int. J. Adv. Res. 9(01), 133-142 134 The optimum level of dietary protein for white shrimp was determined to be 36% by Smith et al. (1985) with three different sizes of white shrimp (4.0, 9.8 and 20.8g and later revised by Lee and Lee (2018) in their study they reported the optimal dietary level of crude protein to be 34. 5, 35.6, and 32.2% for small, medium,and large-sized white shrimps. In addition, Xia et al. (2010) reported that a dietary protein level of around 43% could be optimum for the rearing of L.vannamei in a high-density culture system in the absence of natural productivity The market of commercial shrimp diet can be divided to two different protein levels, a high price product with 41% dietary protein and low price product with 37% dietary protein. The low price shrimp diet contained a higher proportion of plant protein compared to the high price products. Most of the growth promoter in terrestrial animals study has a similar effect on aquatic animals. As a result of differences between shrimp and terrestrial animal in nutrients requirement, shrimp diets were formulated to contain a higher proportion of aquatic animal by-product but terrestrial animal diets contained a higher proportion of plant protein. Most of the KDF study in terrestrial animal shows positive effects on growth performance. Hence, two protein levels of shrimp diet were designed to examine the effect on growth of white shrimp with graded K-diformate supplementation.

Materials and Methods:
Experimental site and design: The study was conducted at the Department of Aquaculture, National Taiwan Ocean University. Post larvaewhite shrimp (Litopenaeusvannamei) of initial mean weight 0.82±0.08g were randomly stocked in 45 aquarium tanks with a working volume of 50 L (60×40×30 cm ) at a stocking density of 10 shrimps per aquarium. Shrimps were acclimated to adapt the experimental conditions through feeding commercial feed for 5 days. The study was conducted with 3 replicate in each treatment for 80 days. Culture shrimps exposed to 18:6 hrs light/dark and received 4 meals a day (0630, 1200, 1800 and 2430 h) during the experiment period, daily feeding rate set at 7% of shrimp body wet weight in the first meal and were adjusted in the following day to maintain a fitness growth performance according to the feed consumption of culture shrimps.
During the experiment, blue canvas were used to avoid aquarium factor, all aquarium was covered by net to avoid shrimp jump out from aquarium. Temperature maintained at 30℃, salinity at 17 0 / 00 and the pH value was monitored within the whole trial. The flowing rate of each aquarium maintained at 2 L/min and decreased to 1 L/min following with UV light deactivated at day 41 th . Ammonia-N was detected below 0.5ppm in the whole trial.

Experiment diet:
The major protein source was Superior standard Chilean fish meal(El golfo fishmeal), wheat flour as binder and wheat gluten were used to adjust the protein level. Two dietary protein levels, 41% dietary protein(CP41) and 37% dietary protein(CP37) was formulated and supplemented of graded K-diformatelevels 0%, 0.1%, 0.2%, 0.4%, 0.8%, 1.4% and 2.0%. Procedures and storage of experimental diets were similar with those described by Baiand Kim. (1997). A commercial diet was taken as a control.

Effects of K-diformate supplement on feed stability in water:
After feed formulation, samples of different diets were randomly taken, an observations were held for 24 hours in order to know the stability of the feed in 17 0 / 00 water.
Effects of feeding diet leaching on water pH: 5g sample of feeding diets was taken randomly and put into 17 0 / 00 water at room temperature maintained approximately at 25℃. pH value of treatments were monitored by pH meter(Suntex SP-701) and recorder (μR1000 Recorder, YOKOGAWA) for 24 hours.

Effects of K-diformate supplement on body colour after cooking:
After the feeding experiment, 3 shrimps from treatments 0%, 0.1%, 0.2%, 1.4% of CP41 and CP37 were randomly sampled. A photographic observation was taken after shrimp cooked in boiled water for 3 minutes

Measurements/calculations and statistical methods:
All shrimp in each aquarium were weightedat 5 interval for growth performances. The first weight was taken at day 20 th , and then each 15 days during the experiment period.
Results are presented as mean ± SEM. Data were subjected to one-way analysis of variance (ANOVA) to test the main effect of K-diformate supplementation. Treatment effects were considered significant at 5%; Duncan's new multiple range tests was used to compare significant difference among treatments. The survival data were transformed into a normal distribution using the arcsine square root prior to analysis of variance. All statistical analysis was carried out using the SAS/PC statistical software.

Results:-Water quality parameters:
The water temperature ranged from 30.62 to 31.42 C; the dissolved oxygen varied between 6.98 to 8.22 mg/L, and the pH ranged from 8.0 to 6.50 (Fig. 1).

Fig. 1:-
The changes of pH value in the recirculating system within growth trial period.

Growth performance:
There is no significant difference in percentage weight gain, SGR, FCR and survival rate in shrimps fed diet supplemented with various level of K-diformate (Fig. 2, 3, 4).

Effects of feeding diet leaching on water pH:
Two protein level with 0%, 0.1%, 0.2%, 0.8% and 2.0% K-diformate supplemented diet in 17 0 / 00 water was undertaken to understand the effect on water pH. The result showed the variation of pH maintained at 5.0-6.5. All diets pH value decreased 0.5 in half an hour, pH value of 0.0, 0.2 and 0.8% K-diformate supplemented diet maintained at pH 6.0 after 11 hours. 2.0% K-diformate supplemented diet reached pH 5.5-6.0 after 11 hours. All diets dropped to pH 5.5 after 15 hours and maintained at pH 5.5 after 19 hours. The result revealed that supplementation of K-diformate did not affect water pH (Fig.5).  138

Effects of K-diformate supplement on feed stability in water:
Two protein level with 0%, 0.1%, 0.2%, 0.8% and 2.0% K-diformate supplemented diet was use to investigate the feed diet stability in water. The result revealed that the water stability of K-diformate supplemented diet, control and commercial diet are similar, K-diformate supplementation in diet do not affect feed diet stability in water (Fig. 6).   The water quality parameters such as the water temperatures, dissolved oxygen and the pH values were within acceptable ranges for L. vannamei culture (Treece, 2000). The unionized ammonia and nitrite values observed in this study remained below the respective safety levels for shrimp culture (Ammonia and nitrites remained between 0.17-0. 19  This could be explained bythe digestive tract of shrimp which is much shorter compared to fishes and other terrestrial animal and that feed evacuation time in digestive tract is short. The above reasons may reduce the efficiency of K-diformate to form a good microbial stage.

Effects of feeding diet leaching on water pH:
All diets pH value decreased 0.5 in half an hour, pH value of 0.0, 0.2 and 0.8% K-diformate supplemented diet maintained at pH 6.0 after 11 hours. 2.0% K-diformate supplemented diet reached pH 5.5-6.0 after 11 hours. All diets dropped to pH 5.5 after 15 hours and maintained at pH 5.5 after 19 hours. The result revealed that supplementation of K-diformate did not affect water pH.The decreasing of water renewing may cause Ammonia-N changed nitrite through nitrification in water, consequently decreased pH level in the water recirculation system.

Effects of K-diformate supplement on feed stability in water:
The result revealed that the water stability of K-diformate supplemented diet, control and commercial diet are similar, K-diformate supplementation in diet do not affect feed diet stability in water.The minimal disintegration of the pellet physical integrity after two hours was good, meaning that the pellet water stability was high. In addition, the high pellet water stability minimize nutrient leaching while in the water until consumed by the shrimps. Shrimps needs that the pellets to be stable in water for few hours (Tacon, 1996).

Effects of K-diformate supplement on body colour after cooking:
The reddish colour to shrimp, which has been associated with its high quality, is one of the major factors for its acceptability by consumers (Parisentiet al., 2011).The result showed in figure 9 and 11, both body colour and deshelled body colour are deeper in shrimp fed with 0 and 0.1% of K-diformate supplemented diet compared to 0.2% and 1.4% of K-diformate supplemented diet. The evidences showed K-diformate supplement might affect absorption of astaxanthin, a further study is needed to prove the above phenomena.

Conclusion and Recommendations:-
The result of this study did not showsignificant difference in percentage weight gain and survival rate among shrimps fed CP41 and CP37 with graded K-diformate supplemented diet. No K-diformatedose response was observed at the end of the study. The results of present study proof that K-diformate supplemented diet do not affect water pH and feeding diet stability in water. A further study is recommended with higher levels of K-diformate addition.