THE ROLE OF INDISPENSABLE AND DISPENSABLE AMINO ACIDS SUPPLEMENTATION IN THE REDUCTION OF DIETARY CRUDE PROTEIN CONTENT IN CHANNEL CATFISH Ictalurus punctatus DIETS

 ¹ Shimaa M. Salem*, 2 D. Allen Davis, 2 Lay Nguyen, ¹ Tarek I. Mohamed, ¹ Ola A. Orma, Lay Nugyen
 
¹ Department of Nutrition & Nutritional Deficiency Diseases, Faculty of Veterinary Medicine  
Mansoura University, 35516 Egypt
2 School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849
davisda@auburn.edu
 

Protein represents about 70% of the dry weight of fish muscle, which is needed for maintenance and growth. In fact Catfish is like other fish species, do not have a protein requirement, but they require a source of nonspecific nitrogen and indispensable amino acids. Usually these nutrients supplied either from a mixture of intact protein sources or by using a mixture of feedstuffs supplemented with purified, crystalline amino acids. These amino acids are utilized for protein biosynthesis and deposition or, used for energy if it supplied in excess. So, catfish feeds should be balanced through the supply of adequate levels of nonspecific nitrogen, amino acids, and non-protein energy in exact proportions. Dispensable amino acids can be synthesized by catfish, but dietary inclusion of these amino acids help to promote growth through saving energy used in their synthesis, and some dispensable amino acids can partially replace some indispensable amino acids.

Growth trial was performed to assess the role of indispensable and dispensable amino acids supplementation in the reduction of dietary protein content in channel catfish Ictalurus punctatus diets and their effect on growth response. 9 isolipid (8%) experimental diets were formulated with different crude protein levels)  32 control, 30, 28, 26, 24 % CP)  with supplementation of Essential amino acids (EAAs) ; Lysine and Histidine  to meet EAAs requirements for channel catfish Ictalurus punctatus according to NRC 2011 with and without addition of  Nonessential amino acids (NEAAs); Glutamic  acid and Glycine  (2, 4, 6, 8% NEAAs) .

Experimental fish (average initial weight 10.56 g)  were randomly distributed into 9 groups, 4 replicate for each 15 fish/ tank in recirculating system, fed experimental diets two times/day % of body weight and weighing bi-weekly for measuring (Mean weight (g), weight gain and feed conversion ratio. Dissolved oxygen, temperature and salinity measure 2times/day while, water samples collect 2 times/week for Total ammonia nitrogen and Nitrite analysis. Also, PH measured by PH meter two times/ week.

The growth results showed that, there is no significant difference (P>0.05) in the final means (g), total weight gain(g) and feed conversion ratio (FCR)  among fish groups which fed with {32 (control), 30, 28 & 26% CP supplemented with EAAs Lysine and Histidine}. However, fish fed with 24 % CP supplemented with EAAs showed statistically different (P<0.05) compared to 32 and 30% CP diets. While the NEAAs supplementation to 24% CP diet with EAAs  did not show an obvious contribution in growth response.