The use of feeds will improve shrimp production and increase profits. However, feeds are expensive and can range from 50% to 70% of the total variable cost of production. As feed quality and cost are directly related, an improvement in feed quality will inevitably increase feed cost. Therefore, feed quality and cost are critical factors in determining the profitability of a shrimp farm.
When purchasing feed, cost per kg feed is irrelevant. Of relevance is feed cost per kg of shrimp produced. For instance, if a feed costs US$ 1.00 per kg and has an FCR of 1.3, feed cost per kg shrimp produced would be US$ 1.30. For another feed which cost US$ 0.75 per kg with an FCR of 2.0, feed cost per kg produced would be US$ 1.50. In this example, the expensive feed is more cost efficient in producing shrimp. Given that the feed cost per kg shrimp produced is similar, the feed with the lower FCR would have less wastes, therefore, better pond water and bottom quality should be achieved.
Feed Requirements Nutrition There are approximately 40 essential nutrients which are believed to be required by shrimp. These nutrients are provided in varying degrees by natural foods and supplemental feeds. Depending upon the availability of natural foods, the nutrient levels may be less than those discussed. This is especially true upon stocking where shrimp biomass in the pond is low. Conversely, if shrimp are grown in less than optimum culture conditions, the required nutrients may be higher. Protein: Proteins are the major organic material in animal tissues constituting 65-75 percent of the total on a dry weight basis. Since proteins are continuously being used by shrimp for growth and normal metabolism, a liberal and continuous supply of protein is needed. Inadequate protein results in reduction or cessation of growth, or a loss of weight due to the withdrawal of protein from tissues to sustain vital functions. Lipid: Lipids are a group of fat-soluble compounds consisting of fats, phospholipids, and sterols. Lipids are concentrated and highly digestible sources of energy, components of tissues, and carriers of fat-soluble vitamins. Lipids are essential for the normal growth and function of shrimp. Fiber: Fiber refers to mixtures of cellulose, hemicellulose, lignin, pentosans, and other generally undigestible fractions in the feed. Fiber is not digested at a significant level to be a factor in the nutrition of shrimp. Feeds with high levels of fiber will increase fecal production and, consequently, pollute the water environment. Ash: Ash refers to the inorganic elements (minerals) in the feed. There are approximately 20 minerals which may be required by shrimp. The essential functions of minerals include constituents of the exoskeleton, and co-factors for normal metabolism and growth. Shrimp can absorb or excrete minerals directly from the aquatic environment via the gills and body surfaces. As brackishwater usually contains a high level of calcium, it is not considered a dietary essential. However, the calcium level in feeds needs to be monitored to maintain a calcium: phosphorus ratio of 1:1 to 1.5:1. Calcium should not exceed 2.3% in the feed. Phosphorus, on the other hand, is usually limited in brackishwater and needs to be supplemented in the feed. Total phosphorus levels in shrimp feeds are approximately 1.5% Feed Bag Labels The labeling of the feed bag with the nutritional content of the feed allows the farmer to compare the nutritional content of the feed with the nutritional content of various feeds. All feeds should be labeled with minimum protein, minimum fat, maximum fiber, maximum ash, calcium, and phosphorus. As shrimp feeds tend to deteriorate quickly, the date of manufacturing should also be indicated, Excessive requirements on feed labels should not be encouraged. The monitoring and regulation of these requirements will incur costs which in turn will increase feed costs. Feed Storage Feed quality will rapidly deteriorate if feeds are not properly stored. Losses also occur if insect and rodent infestation are not controlled. The following are some guidelines to maintain feed quality. Feeds should be stored in a dry, cool, and well ventilated area. Spoilage will occur immediately if feeds become wet. The storage area needs to be cool and well ventilated to maintain consistent temperature in the feed bags. Feeds should be stored on wooden palets (spacers) not more than 5 bags high. This ensures adequate air circulation between feed bags to maintain consistent moisture and temperature levels. Feeds should not be stored directly on concrete floors or in contact with concrete walls. Concrete surfaces are usually cooler than the air surrounding the feed bags. This temperature difference forces the moisture in the feed to migrate to the cool area. Therefore, the area in the feed bags touching the concrete wall will accumulate moisture which encourages mold growth and spoilage. Feeds should not be stored in direct sunlight. This creates temperature changes in the feed (day vs. night) which encourages spoilage. Sunlight will also adversely affect the vitamin and lipid quality of the feed. Feeds should not be stored for longer than 3 months from the time of processing. Vitamin and lipid quality will deteriorate with time. Ideally, feeds should be purchased, delivered, and utilized, on a monthly basis. Spoiled or old feed should not be used. The economic loss of feeding shrimp spoiled or old feed may be greater than discarding the feed.