There has been a lot of interest lately regarding recycling wine industry residues to be useful and beneficial in many different areas, such as meat preservatives, animal feed, food nutrition boosters, disease ameliorators, and alternative fuels. Most research in this field has examined wine industry residues from wine made from grapes (either native or European varieties), however, there are other wine industries throughout the globe with wastes that could potentially be utilized.
Rice wine, which is commonly produced in many Asian countries (choujiu in China, cheong ju in Korea, sake in Japan, santi in Indian, and sato in Thailand), has recently been the focus of such research, and the waste by-products produced examined for potential uses in other systems. Rice wine fermentation is a bit different than grape/fruit wine fermentation, in that it undergoes a process of multiple fermentations occurring in parallel. First, rice starch is converted to sugar by an amylolytic process of fungi. At the same time, sugar is converted to alcohol by the fermentation of yeast cells. The rice wine residual waste is then separated from the liquid, and is usually disposed of.
Studies have found that rice wine waste is rich in nutrition, deriving from both the rice itself and the microorganisms involved in the fermentation processes. Specifically, rice wine waste has been found to be high in protein, which may allow it to be utilized as a supplement in animal feeds. As a result of technological advances in the field of rice winemaking, rice wine wastes are plentiful and the nutritional value consistent from production facility to production facility.
The study reviewed today looked at rice wine wastes as a replacement for fish meal, in order to feed growing tilapia fish. Aquaculture of tilapia has increased dramatically, from 124,000 metric tons in 1997 to 2.5 million metric tons in 2010. Due to the nice flavors, year-round availability, and overall reasonable price point, tilapia has become an important source of protein for many middle-class families and demand continues to increase, requiring production costs to decrease.
One way in which producers have been seeking to decrease production costs is in the feed used to raise juvenile fish. In order to raise quality adults, juvenile fish require high quality food sources that are rich in protein, for proper growth and development. In the past, fish meal was the primary protein source for juvenile fish, however, it has been relatively scarce and the supply inconsistent as of late, therefore alternative food sources are required to keep production costs low.
The study presented to you all today aimed to evaluate the use of rice wine wastes, which are known to be high in protein, as an alternative protein source for juvenile tilapia fish.
Rice wine wastes were obtained from the Samrithmankong factory in Nakhon Ratchasima, Thailand. For the wastes, dry matter, protein, total lipids, fibre, ash, and amino acid composition were analyzed.
All other feed test substances were obtained from animal feed companies. Before experimenting with different feeds, all ingredients were analyzed for percentages of moisture, protein, lipid, and ash. 7 total feed diets were created, which incorporated 0, 75, 150, 225, 300, 375, and 450g/kg of rice wine wastes, respectively. In order to create food pellets that float (a requirement for juvenile tilapia), corn meal and cassava chips were added so that all feeds contained up to 250g/kg of flour. All diets were created to not have a protein:energy ratio less than 18mg/J, which is the minimum amount required for juvenile tilapia development. After they were created, all test feeds were analyzed for their composition and stored at room temperature until needed.
|Table 2 from Vechklang et al, 2011. Composition of the 8 treatment diets for tilapia.|
Seven generations of male tilapia were raised at the Suranaree University of Technology Farm in Nakhon Ratchasima, Thailand.
The experimental design was completely randomized, and contained 8 treatment feeds that were each replicated 3 times with 55 fish each. 24 hapas (a.k.a. floating fish pens, 2×2.5×2 m3) were used during the experiments, with fish randomly assigned to each one. For the first two weeks of the experiment, fish were fed Diet 1 (the control diet with no rice wine waste residues) in order to acclimate to the environment. Afterwards, during the experiment itself, fish were hand-fed experimental diets twice daily for 6 weeks. Dead fish were removed daily, and growth performance and feed utilization were measured at the end of the 4th week.
Haematological and blood chemical parameters were measured for four fish per diet treatment. Fillets were cut and analyzed, and the liver analyzed for the hepatosomatic index. Specifically, the following biological and biochemical parameters were measured: haematocrit values, haemoglobin content, red blood cell count, blood glucose, blood urea nitrogen (BUN), cholesterol, serum lysozyme activity, and intestinal morphometry.
Water quality was analyzed by collecting samples at 15cm in depth for 8 weeks. Water quality was determined by measuring the following: dissolved oxygen, turbidity, suspended solids, total dissolved solids, chemical oxygen demand, biochemical oxygen demand, conductivity, and pH.
- All water quality values were found to be within the acceptable range for each component measured.
- The rice wine waste contained a high level of essential amino acids required for tilapia development.
- Tilapia fed diets supplemented with rice wine waste up to 225g/kg showed a similar growth response as those tilapia fed the control feed.
o There was a significant, non-linear relationship between rice wine waste in feed and weight gain in tilapia.
- Feed conversion ratios and protein efficiency ratios were similar in all treatment feeds.
- Survival rates for all treatment feeds were high: 97-99% survival.
- Hepatosomatic index of tilapia did not vary significantly between treatment groups.
- There were no significant differences in the chemical compositions of fillets cut from fish in each treatment group.
- Red blood cell count did not vary significantly between treatment groups.
- Haematocrit levels of tilapia on treatment feeds with 375 and 450g/kg rice wine waste was significantly lower than the control treatment at 3 weeks, though by the end of the experiment, there were no significant differences.
- Haemoglobin levels were significantly lower in tilapia fed 375 and 459g/kg rice wine waste feeds by the end of the experiment.
o There was a significant, linear relationship between rice wine waste in feed and haemoglobin content.
- Lysozyme activity was similar in tilapia in all treatments.
- BUN levels of tilapia on treatment feeds with 375 and 450g/kg rice wine waste was significantly lower than the control treatment at 3 weeks, though by the end of the experiment, there were no significant differences.
- Blood glucose levels increased with increasing rice wine waste in feed.
o There was a significant, non-linear relationship between rice wine waste in feed and blood glucose levels in tilapia.
- Blood cholesterol decreased with increasing rice wine waste in feed, and was lower than the levels in the tilapia given the control feed.
- Duodenal height and thickness did not vary significantly between treatment groups.
- The number of goblet cells in the duodenum significantly decreased in fish fed the 450g/kg rice wine waste feed.
o There was a significant, non-linear relationship between rice wine waste in feed and the number of goblet cells in the duodenum (part of the intestine) of tilapia.
- Villus height in the jejunum was significantly lower for tilapia fed the 450g/kg rice wine waste feed.
o There was a significant, non-linear relationship between rice wine waste in feed and the villus height in the jejunum (part of the intestine) of tilapia.
It is clear from the results presented in this study, that rice wine wastes are a suitable protein source for developing juvenile tilapia, up to a concentration of 225g/kg. Higher concentrations, though not differing in the survival rates, started to show poorer intestinal development and poorer overall health of the juvenile fish, as indicated in the blood chemistry data. It is unclear exactly why higher concentrations of rice wine wastes in feed negatively effects blood chemistry and intenstinal health, however, there may be some effect on the immune system of the fish that warrants further study.
The most detrimental effect of higher concentrations of rice wine waste in feeds seemed to be related to the intestinal health of the fish, which resulted in negative effects on intestinal morphology. Villus height and epithelium thickness aid in the absorption process of nutrients, both of which were negatively affected by higher concentrations of rice wine wastes in feeds (villus height most significantly). Globet cells, which were also negatively affected by high concentrations of rice wine wastes in the feed, play a critical role in synthesizing mucus into the mucosal layer of the intestine, which acts to destroy pathogens. Since high concentrations of rice wine waste in feed negatively affected both villus height and globet cells, intestinal functions which aid in the growth and development of tilapia were damaged, thus resulting in fish of poorer health than those fed the control fed or feeds with rice wine waste concentrations lower than 225g/kg.
Overall, provided the concentrations are not higher than 225g/kg, this study shows that using rice wine waste residues as a protein supplement in feed will not have any negative effects on growth or health status of tilapia. This is promising for both the rice wine industry, who may not recycle their wastes in a more “environmental friendly” manner, and also the tilapia farmers, who now have an alternative to fish meal that is no more costly and more readily available.
This made me think, however…could we also use Vitis vinifera wine industry residues in the same manner? If so, would eating tilapia (or other fish) fed a diet supplemented with these residues (which are high in heart-healthy polyphenols) be healthier than eating tilapia fed with the more traditional fish meal diet?
I’d love to hear what you think about this topic! Please feel free to leave your comments below!
Source: Vechklang, K., Boonanuntanasarn, S., Ponchunchoovong, S., Pirarat, N., and Wanapu, C. 2011. The potential for rice wine residual as an alternative protein source in a practical diet for Nile tilapia (Oreochromis niloticus) at the juvenile stage. Aquaculture Nutrition 17: 685-694.
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!