INCLUSION OF A HIGH PROTEIN DISTILLERS DRIED GRAINS PRODUCT IN NILE TILAPIA DIETS

Khaled Mohamed Wasly 1 , Ashraf H. Gomaa 1 and Wafai Z. A. Mikhail 2 . 1. Regional Center for Food and Feed, Agriculture Research Center, Giza, Egypt. 2. Dept. Natural Resources, Inst. African Research & Studies, Cairo University. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 05 September 2018 Final Accepted: 07 October 2018 Published: November 2018

Chemical analysis:-Analysis of different experimental feed ingredients, formulated diets were carried out for moisture, nitrogen, ether extract, crude fiber and nitrogen free extract according to the procedures of Association of Official Analytical Chemists (AOAC, 2005) using triplicate samples for each determination, Crude protein was calculated as nitrogen content x 6.25.
Amino acid determination:-Amino acids except tryptophan and tyrosine were individually determined according to the method of Official Journal of European Communities (1998). The composition of the experimental diets used in the feeding trials is presented in Table (2). The proximate chemical analysis and the energy content of the diets are presented in Table (3), while their amino acid analysis is presented in Table (4). Feed ingredients were finely grinded and mixed manually. Water was added to each diet till paste was formed, and then passed through a meat mincer machine to convert the mixture into pellets. The wet pellets were then sun dried and stored at -20°C until used. Each diet was tested by three groups of 15 fish each. Fish fed five times a day, at a daily rate of 4% of fish body weight for 12 weeks. Every two weeks fish in each aquarium were weighed and the ration offered was altered according to their body weight.
At the beginning of the experiment, one hundred fish were used as an initial control group. They were killed and kept frozen for chemical analysis. At the end of the experiment all fish in all aquaria were killed and kept frozen for chemical analysis.   Table 4:-Essential amino acid analysis of the experimental diets (g/ 100 g crude protein), used in the feeding trial, and amino acid requirements for Nile tilapia after (Santiago and Lovell, 1988  The present results of this study indicate that dietary supplementation of DDGS up to 30% did not affect the growth performance of Nile tilapia fingerlings (P ≤ 0.05). While Nile tilapia fingerlings fed 45% DDGS diets showed the lowest growth performance values (P ≤ 0.05), these may be due to the lower contents of lysine amino acid and increased fiber in diets.

Our results are in agreement with previous studies (Tidwell et al., 1990; Robinson and Li, 2008; Li et al., 2010)
have also reported that corn-based DDGS can be integrated into channel catfish diets without negative effects on growth performance, and is suitable to replace soybean meal and corn meal in hybrid catfish diets (Zhou et al.,  2010). The effectiveness of a diet containing DDGS on the growth of freshwater fishes is related to several factors such as improved digestibility (Randall and Drew, 2010) and decreased exposure to anti nutritional factors (Borgeson et al., 2006). Nile tilapia grew bad at low levels of lysine amino acid, when fish fed 40% DDGS diet without lysine supplement (Lim et al., 2007).
Fish group given HPDDGS diet levels 15% HPDDGS, 30% HPDDGS, and 45% HPDDGS, with lysine supplementation showed better in the growth performance in terms of final mean weight, weight gain and average daily gain when compare with the control diet (P ≤ 0.05).
These  Barnes et al. (2012 a, b) showed that the inclusion of up to 200 g kg-1dietary DDGG or HPDDG had no adverse effects on growth and feed intake in rainbow trout.

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These results also are in agreement with those of Wu et al. (1994 and 1995),who reported that diets containing corn distiller's grains with solubles 29% and 32% or 36% protein resulted in higher weights of tilapia. (Thompson et al.,  2008) observed that corn-based DDGS might be improved palatability in Sunshine Bass diet. On the other hand, Lim et al. (2009) showed that up to 40% corn-based DDGS could be included in the diet of channel catfish as a replacement of soybean meal and corn meal without affecting weight gain.
In the present study, decreased growth performance and feed utilization at high dietary inclusion levels of DDGS (45%DDGS) may be associated with various factors including increased fiber levels, reduced feed palatability and an imbalanced dietary amino acid profile (lysine). Fibers and anti-nutrients are related to reduce digestibility in catfish (Francis et al., 2001).
Reductions in growth and feed utilization of fish fed plant protein due to imbalanced dietary amino acids reduced mineral content, increased fiber, reduced palatability, and the presence of anti-nutrient factors (Lim and Lee, 2009).
Data representing means for feed conversion ratio (FCR), protein efficiency ratio (PER) and Protein Productive Value (PPV %) for fish given diets containing different levels of both DDGS and HPDDGS are presented in Table  (6). Feed utilization efficiencies in terms of food conversion ratio (FCR), protein efficiency ratio (PER) and Protein Productive Value were also significantly affected by the treatments (P ≤ 0.05). The Feed conversion ratio (FCR) of fingerlings Nile tilapia fed 15 %DDGS and 30% DDGS diets, were slight different compared to the control diets, but fingerlings Nile tilapia fed 45% DDGS diets worst FCR when compared to other treatments. The highest FCR, lowest PER and the lowest (PPV %) representing the worst findings were achieved when fish was fed on diet containing 45% DDGS diets.
These results are in agreement with those of Lim and Webster (2006) who found that 20% fuel-based DDGS can be included in Nile tilapia diets without a significant effect on overall growth performance. However, fish fed diets containing 30% DDGS had similar weight gain (WG), PER and feed efficiency ratio (FER) as those fed the control diet, while fish fed 40% DDGS had significantly lower WG, PER and FER than those on the control diet. Similar results were obtained by Li et al. (2011), who found significant decrease (P≤ 0.05) in growth rate and FCR when 40% soybean meal and corn without addition lysine was replaced with wheat DDGS in tilapia diets. Also, these results are in agreement with previous studies in DDGS inclusion in tilapia diet, which showed that 40% DDGS level in fish diet resulted in lower growth and feeding performance according reported that increasing dietary levels of DDGS to 40% without addition of lysine significantly reduced WG and PER compare to those obtained with diets containing lower DDGS levels (0, 10, and 20%), FCR of this diet (40% DDGS) was also significantly worst than that of the control diet. Results of earlier studies have shown that based on growth performance and feed utilization efficiency, DDGS is a promising feed ingredient for several fish species, including rainbow trout (Cheng and Hardy, 2004), tilapia (Wu et al., 1996), and channel catfish (Tidwell et al., 1990;  Webster et al., 1993). The lowest FCR, highest PER and the highest PPV% were achieved when fish was fed on the 447 HPDDGS diet levels 15%HPDDGS, 30%HPDDGS and 45%HPDDGS, with lysine supplementation. This is an agreement with the findings of Barnes et al. (2012a) and Cheng and Hardy (2004), who showed that the, final weight, FCR, PRE, P retention, and SGR of fish fed HPDDG were greater than those of fish fed the control diet.
From this study, the nutritive value of HPDDGS was investigated and showed very high digestibility of protein and amino acid, this feed ingredient appeared to be a good protein source in the low fishmeal diet for rainbow trout (Prachom et al., 2013). The results of this experiment suggest that DDGS is a good substitute for plant materials such as Yellow corn and soybean meal, and can be used up to 30% in feed to maintain the growth performance of Nile tilapia, and also fish group given HPDDGS diet levels (15%HPDDGS, 30%HPDDGS, 45%HPDDGS), with lysine supplementation showed better in the Growth performance and feed utilization. HPDDGS is a good alternative protein source and can be used up to 45% or may be more with lysine supplementation.