Effects of Stargrass Hay Supplementation on Growth and Survival of Juvenile Redclaw Crayfish Cherax quadricarinatus

Abstract

Hay is used as supplementary forage for crayfish aquaculture in many farms around the world. However, our understanding of the relative contribution of hay to crayfish dietary requirements is limited. In the present work, 36 juvenile redclaw crayfish Cherax quadricarinatus were stocked into each of 28 tanks that received water continuously from a pond. Four replicate tanks were assigned to each of seven dietary treatments: commercial formulated feed (FF) only, at a ration calculated to produce optimal growth; 100% of the calculated FF ration plus the hay of stargrass Cynodon nlemfuensis added at 150 kg·ha⁻¹·week⁻¹; 75% of the FF ration plus hay; 50% of the FF ration plus hay; 25% of the FF ration plus hay; hay only; and no feed (control). At the end of 8 weeks, the crayfish were harvested, counted, and weighed. There were no significant differences in survival among treatments (α = 0.05), and crayfish growth did not differ among tanks that were offered FF. Redclaw crayfish in the hay-only treatment grew less than those that were offered FF, but growth did not differ between crayfish that were offered only hay and crayfish in the no-feed control. Although hay did not contribute to the growth of redclaw crayfish that were offered the high-protein shrimp feed, it did allow for survival and minimal growth of crayfish that were not offered FF. Accordingly, hay might contribute to growth if a low-protein, low-energy diet is developed specifically for crayfish.

Received February 25, 2011; accepted April 26, 2011

Notes

^aThe FF (manufactured by Rangen, Angleton, Texas) contained 35% crude protein, 7% lipid, and 3% fiber.