Food Intake And Feeding Strategy Of Yellow Catfish Pelteobagrus Fulvidraco

Yellow catfish(Pelteobagrus fulvidraco Richardson) belongs to Siluriformes, Bagridae, Pelteobagrus. It already becomes an important cultured species in recent years. In this paper, we studied diet composition, preference and daily feeding rhythms of larval and juvenile yellow catfish reared in fertilised earthen ponds, and effect of feeding strategy on growth and survival, feed utilization, body composition and energy budget of juvenile yellow catfish in order to reveal the regularity of ingestion and growth in early life history of yellow catfish, but also to supply scientific guidance for fry rearing and breeding management of yellow catfish. The results of this study are summarized as follow.1. Food intake of yellow catfish in early developmental stagesThe diet composition, feeding behavior and daily feeding rhythm of yellow catfish were studied through the method of experimental ecology in the paper. The results were as following:Larvae and juvenile mainly fed on zooplankton, and their diet also changed with their growth. Larvae fed on cladocerans and rotifera in the first feeding stage (9th day after hatched); after that, juvenile mainly fed on copepoda. Moreover, the zoobenthos, chironomid larvae et al., from 54.84% for day-13 to 69.52% for day-23, occupied the main superiority in food composition. Day and night feeding rhythm was observed apparently in larval and juvenile stages. The highest levels of feeding activity at 20:00 for day-9, after that, The peak means stomach fullness index of all achieved at 4:00. The feeding levels at night were significantly higher than that in day, the circadian feeding rhythm of yellow catfish belongs to nocturnal obviously.2. Effect of feeding level on growth, body composition and energy budget of juvenile yellow catfishThe optimum feeding level and effect of feeding levels on the growth performance, body composition and energy budget for juvenile yellow catfish under different feeding levels(100%(satiation),90%,80%,70%,60% and 50% of satiation every day respectively) were determine in this experiment. The results showed that effect of feeding levels on growth of yellow catfish was significant. With the feeding levels increasing, feeding ratio and relative rate of body weight increase had increased gradually, while the coefficient of variation of body length and weight increased at first, then decreased; Specific growth rate (SGR) in wet weight (SGRW), dry weight (SGRd), protein (SGRP) and energy (SGRe) of juvenile yellow catfish increased significantly (P<0.05) with feeding level; Feed conversion efficiency (FCE) in wet weight (FCEW), dry weight (FCEd) and energy (FCEe) increased with feeding level, peaked at 70% of satiation, and then decreased at higher ration; The maximum value of feed conversion efficiency (FCE) in protein (FCEP) is 50% of satiation,70% of satiation followed, but no significant difference between the two groups (P<0.05); The FCEW,FCEd,FCEp of 100% group were significantly lower than other treatments (P<0.05); Apparent digestibility coefficients in dry matter (ADCd) and energy (ADCc) of yellow catfish increased fist and then decreased, Apparent digestibility coefficients in protein (ADCP) decreased significantly (P＜0.05) as feeding level increased; In addition, fat content of yellow catfish increased, and ash content decreased. However, moisture and protein content were no significant effect.There were significant influence in energy budget with different feeding levels (P＜0.05). The proportions of energy intake lost in faecal production and excretion tended to increase with the increasing of feeding level; As feeding level increased, the proportion of energy intake spent in metabolism decreased significantly(P＜0.05), whereas the proportions of energy intake stored in body as growth energy increased with the ration level, peaked at 70% of satiation, and then decreased at higher level; With the increasing of feeding level, the proportion of assimilation energy channeled into metabolism decreased markedly, while the proportion recovered in growth increased markedly.According to the growth and feed utilization indices, combined with results of bioenergetics, the present study suggested that the appropriate feeding level should be 70% of satiation.3. Effect of feeding frequency on growth, feed utilization and body composition of juvenile yellow catfishThe experiment was conducted for 8 weeks in order to determine the effects of different feeding frequencies(1,2,3 and 4 times every day respectively) on the growth, feed efficiency and body composition of juvenile yellow catfish with average weight (0.88±0.16)g. The results showed that, with the increasing of feeding frequency, the length gain, relative rate of body weight increase, feed efficiency and specific growth rate increased first and then decreased, and the group which was fed 3 times per day was the highest and significantly different from other groups (P＜0.05); Relationship between specific growth rate (SGR) and feeding frequency (FF) was described with the equation: SGR=0.4733+1.1879FF-0.2009FF2(R2=0.9765).There were significant influence in body composition of yellow catfish (P＜0.05). with the increasing of feeding frequency, moisture content and ash content decreased, protein content increased at first, then decreased. However, fat content was increased significantly (P＜0.05).The conclusion of the data showed that the effect of feeding frequency on the growth of yellow catfish result from the increase of both feed efficiency and feeding rate. The present study suggested that the feeding frequency of three meals per day is optimal for the culture of yellow catfish.