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Lysine addition to swine diets via either feed-grade lysine or protein sources costs producers. To better understand how diet affects lysine oxidation (LOX), weanling pigs were fed a control (C), high protein (HP), low protein (LP), high lysine (HL), or low lysine (LL) diets. No diet-induced alterations in lysine catabolism were detected in heart or kidney (P > 0.05). Liver lysine α-ketoglutarate reductase (LKR) (P

The activity of lysine α -ketoglutarate reductase (LKR), the initial enzyme in the principal pathway of lysine catabolism, is a primary determinant of whole-body lysine status. Past research indicated that LKR activity was predominantly hepatic; recent in vivo data suggest that other tissues can also catabolize lysine. The hypothesis of this investigation was that lysine catabolism takes place in extrahepatic tissues in pigs and that the enzymes involved may be subject to inhibition or activation. Using mitochondria from various tissues of market-age pigs, the activities of LKR and saccharopine dehydrogenase were measured. Liver mitochondria had the highest LKR activity, and the enzyme was subject to substrate inhibition. Mitochondria from the muscle, kidney, heart, and intestinal epithelial cells all had measurable LKR activity. The LKR activity was significantly inhibited by a variety of compounds including saccharopine, α -aminoadipate, α -ketoadipate, 5-hydroxy-l-lysine, and several metals. Oxidation of 14 C-lysine to 14 CO 2 was demonstrated in mitochondria isolated from the liver, muscle, and intestinal epithelial cells. Western blotting confirmed the presence of the α -aminoadipate δ-semialdehyde synthase protein in some extrahepatic tissues. These data show a significant capacity for lysine degradation in these extrahepatic tissues, most notably in cells of the intestine and muscle. These tissues should be considered important contributors to whole-body lysine catabolism.

This study was to create an ω-3 (n-3) fatty-acid-enriched chicken product using defatted green microalgae (DGA, Nannochloropsis oceanica) biomass out of biofuel research. Hatching Ross broiler chicks were fed a corn–soybean meal diet containing 0 (control), 2, 4, 8, or 16% DGA for 6 weeks (n = 6 cages/diet). The DGA inclusion resulted in a linear (p < 0.001) increase in total n-3 fatty acids, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) in plasma, liver, breast, and thigh at weeks 3 and 6. The increase in the breast EPA + DHA by the 16% DGA diet reached 60-fold (p < 0.0001) over the control. The 8 and 4% DGA diets elevated (p < 0.05) liver mRNA levels of Δ-9 (88%) and Δ-6 (96) desaturases. In conclusion, 8–16% of the DGA can be added in diets for broilers to produce a n-3 fatty-acid-enriched chicken meat.

Two experiments were conducted to determine the nutritional and metabolic impacts of defatted green microalgal (Desmodesmus sp.) biomass (DGM), protease, and nonstarch polysaccharide degrading enzymes (NSPase) in diets for weanling pigs and broiler chicks. Pigs fed 10% DGM for 28 days had growth performance comparable to the controls, but 23-39% lower (P < 0.05) plasma urea nitrogen concentrations. Broilers fed 15% DGM had 16% greater (P < 0.05) gain/feed efficiency than the control (0.78 vs 0.67) over the 42 day period. Supplemental protease (0.06%) decreased (P < 0.03) plasma uric acid concentrations in pigs on day 14, whereas supplemental NSPase showed negative effects in broilers. Dietary inclusions of DGM or enzymes altered (P < 0.05-0.1) hepatic and muscle protein levels of key regulators in the mTOR pathway. In conclusion, weanling pigs and broiler chicks tolerated dietary inclusions of 10 and 15% DGM, respectively, and adding protease might help digestion.