Three experiments were conducted to determine if defatted diatom Staurosira sp. biomass (DFA) (Cellana, Kailua-Kona, HI, USA) from biofuel production could replace a portion of soybean meal (SBM) and (or) corn in diets for broiler chicks. In experiment 1, 2-day-old chicks were fed diets with DFA at 0% (control), 7.5% replacing SBM, or 7.5 and 10% replacing SBM and corn. Chicks fed the DFA-containing diets had lower body weight gain (P < 0.05) than the controls in the starter period. Two follow-up experiments, experiments 2 and 3, indicated that supplementing the 7.5% DFA diet (replacing SBM) with amino acids, but not exogenous protease or electrolytes, restored growth performance of chicks to the control levels. Responses of plasma and liver biomarkers and gross examination of digestive tract showed no toxicity of DFA. In conclusion, DFA could substitute for 7.5% of SBM alone, or in combination with corn, in diets for broiler chicks when appropriate amino acids are added.

While feeding food-producing animals with microalgae was investigated several decades ago, this research has been reactivated by the recent exploration of microalgae as the third generation of feedstocks for biofuel production. Because the resultant defatted biomass contains high levels of protein and other nutrients, it may replace a portion of corn and soybean meal in animal diets. Our laboratory has acquired 4 types of full-fat and defatted microalgal biomass from biofuel production research (Cellana, Kailua-Kona, HI) that contain 13.9 to 38.2% crude protein and 1.5 to 9.3% crude fat. This review summarizes the safety and efficacy of supplementing 2 types of the biomass at 7.5 to 15% in the diets of weanling pigs, broiler chicks, and laying hens. Based on their responses of growth performance, egg production and quality, plasma and tissue biochemical indicators, and/or fecal chemical composition, all 3 types of animals were able to tolerate the microalgal biomass incorporation into their diets at 7.5% (on as-fed basis). Holistic analysis is also provided to explore the global potential of using the defatted microalgal biomass as a new feed ingredient in offsetting the biofuel production cost, reducing the dependence on staple crops such as corn and soybeans, decreasing greenhouse gas production of animal agriculture, and developing health value-added animal products.

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.

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.

The primary pathway of lysine degradation in pigs presumably depends on the bifunctional protein α-aminoadipate δ-semialdehyde synthase (AASS), which contains lysine α-ketoglutarate reductase (LKR) and saccharopine dehydrogenase (SDH) activities. In liver, AASS is restricted to the mitochondrial matrix and lysine is presumptively transported through the plasma membrane by a cationic AA transporter (CAT1/2) and through the inner mitochondrial membrane by 1 or both mitochondrial ornithine transporters (ORC-1/ORC-2). Lysyl oxidase (LO) may represent an alternative pathway of lysine oxidation. The objective of this experiment was to analyze the distribution of indices of lysine catabolism in various pig tissues. We assessed LKR, SDH, and LO activities, lysine oxidation, mRNA abundance of LKR, CAT1/2, and ORC1/2, and AASS protein abundance (via SDH antibody) in liver, heart, kidney medulla and cortex, triceps, longissimus, whole intestine, enterocytes, and intestine stripped of enterocytes in 10 growing pigs, weighing ∼25 kg. The LKR activity differed across tissues (P<0.001) and was greatest in liver, intestine, and kidney samples, and LKR mRNA abundance (P<0.001) was greatest in liver; although, LKR activity and mRNA abundance were detected in all other tissues. Activity of SDH (P<0.001) and SDH mRNA abundance (P<0.001) were affected by tissue and were greatest in liver compared with all other tissues analyzed. The AASS protein abundance (P<0.001) was greatest in whole intestine and liver. Activity of LO (P<0.0001) was greatest in muscle samples. The abundance of ORC-1 (P<0.001) and ORC-2 mRNA (P<0.001) differed among tissues, and ORC-1 was greatest in liver, kidney, and intestinal preparations, and ORC-2 mRNA abundance was greatest in liver and intestine. Interestingly, LKR activity was correlated with ORC-1 (r=0.32, P<0.05) and ORC-2 (r=0.41, P<0.05) expression. The expression of CAT-1 was uniform in all tissues, whereas CAT-2 (P<0.01) was greatest in liver. In conclusion, these data indicate that extra-hepatic tissues contribute to lysine catabolism as do enzymes other than LKR.