Semester

Fall

Date of Graduation

2008

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

Kenneth P. Blemings.

Abstract

How an organism reacts to consuming a lysine deficient diet was examined in two different circumstances. First, the responses of ten different genetic lines of rainbow trout were observed while consuming a lysine-deficient (LD) diet, used to mimic a soybean meal-containing diet. The aquaculture industry is investigating the incorporation of soybean meal into carnivorous fish diets to alleviate the need for fishmeal. If soybean meal is incorporated into the diet, an assessment of the genetic strains of fish used in the aquaculture industry today must be performed since differences in genetics have been shown to effect growth. When compared to rainbow trout consuming a lysine-adequate (LA) diet, those consuming the deficient diet had a significant reduction in weight gain (P<0.01), average daily feed intake (P<0.01) and feed efficiency (P<0.0001), while having increased hepatosomatic index (P<0.01) and lipid content (P0.05) when compared to those consuming the LA diet. These data indicate that a LD diet was successfully constructed. When the ten families consuming the LD diet were examined, there was variation in final weight (P<0.0001), feed intake (P<0.0001) and feed efficiency (P<0.0001). There was also trend for variation in oxygen consumption (P=0.068) among families, and there was no difference in indices of lysine metabolism among families. These data indicate that there is some genetic component influencing the ability of the fish to adapt to a LD diet, in that some families of fish out-perform others when consuming this diet. Lysine is degraded in mitochondrial matrix, but the mechanism of transport into the matrix is unknown. Second, changes in the mitochondrial proteome of broilers adapted to a LD diet were assessed. Two transport proteins were affected by the LD diet. Broilers consuming the deficient diet exhibited a 50% reduction in the expression of a voltage-gated anion-selective channel and a voltage-gated potassium channel compared to those consuming a LA diet, although it is unlikely that lysine is transported via either of these proteins. The consumption of the LD diet also impacted many aspects of metabolism. Glutamine synthase expression was decreased over 95% in the chickens consuming the LD diet, compared to the LA diet. Electron transport chain (ETC) components were also altered. Broilers consuming the LD diet had over a 30% reduction in NADH dehydrogenase expression, or Complex I, and almost a 90% decrease in the expression of ATP synthase, or Complex V of the ETC. The reduction in proteins involved in the ETC may contribute the reduction in growth (P<0.05) seen in the broilers consuming the LD diet. Proteins involved in fatty acid oxidation were also affected by the LD diet, as Acyl CoA dehydrogenase was reduced about 75%. These data indicate that a LD diet affects many aspects of metabolism, possibly explaining the reduction of growth typically seen with a lysine deficiency.

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