Skeletal muscle and liver gene expression profiles in finishing steers supplemented with Amaize.

Our main objective was to evaluate the effects of feeding α-amylase (Amaize, Alltech Inc., Nicholasville, KY, USA) for 140 days on skeletal muscle and liver gene transcription in beef steers. Steers fed Amaize had lower average daily gain (p = .03) and gain:feed ratio (p = .05). No differences (p > .10) in serum metabolites or carcass traits were detected between the two groups but Amaize steers tended (p < .15) to have increased 12th rib fat depth. Microarray analysis of skeletal muscle revealed 21 differentially expressed genes (DEG), where 14 were up-regulated and seven were down-regulated in Amaize-fed steers. The bioinformatics analysis indicated that metabolic pathways involved in fat formation and deposition, stress response, and muscle function were activated, while myogenesis was inhibited in Amaize-fed steers. The quantitative PCR results for liver revealed a decrease (p < .01) in expression of fatty acid binding protein 1 (FABP1) and 3-hydroxybutyrate dehydrogenase 1 (BDH1) with Amaize. Because these genes are key for intracellular fatty acid transport, oxidation and ketone body production, data suggest a reduction in hepatic lipid catabolism. Future work to investigate potential positive effects of Amaize on cellular stress response, muscle function, and liver function in beef cattle appears warranted.

Effects of a docosahexaenoic acid-rich microalgae nutritional product on insulin sensitivity after prolonged dexamethasone treatment in healthy mature horses.

OBJECTIVE: To determine effects of a microalgae nutritional product on insulin sensitivity in horses. ANIMALS: 8 healthy mature horses. PROCEDURES :Horses (n = 4/group) received a basal diet without (control diet) or with docosahexaenoic acid-rich microalgae meal (150 g/d) for 49 days (day 0 = first day of diet). On day 28, an isoglycemic hyperinsulinemic clamp procedure was performed. Horses then received dexamethasone (0.04 mg/kg/d) for 21 days. On day 49, the clamp procedure was repeated. After a 60-day washout, horses received the alternate diet, and procedures were repeated. Plasma fatty acid, glucose, and insulin concentrations and glucose and insulin dynamics during the clamp procedure were measured on days 28 and 49. Two estimates of insulin sensitivity (reciprocal of the square root of the insulin concentration and the modified insulin-to-glucose ratio for ponies) were calculated. RESULTS: Baseline glucose and insulin concentrations or measures of insulin sensitivity on day 28 did not differ between horses when fed the control diet or the basal diet plus microalgae meal. On day 49 (ie, after dexamethasone administration), the microalgae meal was associated with lower baseline insulin and glucose concentrations and an improved modified insulin-to-glucose ratio for ponies, compared with results for the control diet. CONCLUSIONS AND CLINICAL RELEVANCE: Although the microalgae meal had no effect on clamp variables following dexamethasone treatment, it was associated with improved plasma glucose and insulin concentrations and insulin sensitivity estimates. A role for microalgae in the nutritional management of insulin-resistant horses warrants investigation.