Use of mixed feeding schedules in fish culture: field trials on catla, Catla catla (Hamilton-Buchanan), rohu, Labeo rohita (Hamilton), and common carp, Cyprinus carpio L.

Abstract. The applicability of mixed feeding schedules using low-and high-protein diets was evaluated by three on-farm field trials conducted in fertilized earthen ponds. Rohu, Labeo rohita (Hamilton), and common carp, Cyprinus carpio L., were used in the first two trials, and catla. Catla catla (Hamilton-Buchanan), was also included in the third trial. The concept of a mixed feeding schedule was tested using a 1:1 rice bran-groundnut meal cake mixture, a commonly used feed in Indian carp culture. In a mixed feeding schedule, two feeds are used alternately, each for a predetermined number of days. In the present study, one of three such mixed feeding schedules was used in conjunction with one of two control diets. The control diets were rice bran (diet A) or a mixture of rice bran-groundnut meal cake (diet B). The mixed feeding schedules tested were: 1A/1B, 1A/2B and 1A/3B (numerals indicate number of days diet A or B was offered continuously). Diet A (rice bran only) induced significantly poor growth in all treatments. Interestingly, growth in the mixed feeding schedules was generally equal or superior to that when fish were fed with diet B. Growth efficiency indicators such as SGR. FCR and PER were found to be good for fish maintained on certain mixed schedules. Savings of 15–31% protein and 10–20% of the feed cost were achieved with the various schedules, the highest saving being achieved with the 1A/1B schedule. Nitrogen retention was higher in fish treated with mixed schedules. The results demonstrated the usefulness of mixed schedules in reducing nitrogen input, output and feed costs.