Feeding dihydroquercetin and vitamin E to broiler chickens reared at standard and high ambient temperatures.

The use of natural antioxidants, in particular polyphenols such as dihydroquercetin (DHQ), in animal nutrition has recently increased in popularity. This may partly be due to the risk of increased incidences of heat stress associated with raising livestock in warmer ambient temperatures, facilitated by global warming, reducing antioxidant capacity. The current research demonstrates the effect of dietary DHQ, vitaminEand standard or high ambient temperatures on growth performance, energy and nutrient metabolism, gastrointestinal tract (GIT) development, jejunal villus morphometry and antioxidant status in broiler chickens. Each of the four experimental diets was fed to 16 pens of five birds, which were allocated to four rooms (four pens in each room). The temperature in two rooms was maintained at aconstant 35°C (high temperature; HT), and the temperature in the other two rooms was gradually reduced from 27°C at 7 dof age to 22°C at 20 dof age (standard temperature; ST). Rearing birds at HT reduced feed intake, weight gain, weight of small intestine, total GIT, liver, spleen, heart, villus height, villus surface area and lowered blood glutationperoxidase (GSH-Px). Dietary DHQ increased blood GSH-Px and total antioxidant status, increased heart weight and reduced caecal size. When fed separately, DHQ and vitamin E improved hepatic vitamin E concentration. Feeding vitamin Eincreased spleen and liver weights. When fed together, DHQ and vitamin Ereduced villus height, villus height to crypt depth ratio and villus surface area. Temperature and antioxidants did not affect energy and nutrient metabolism. There were no effects of dietary antioxidants on growth performance of broiler chickens and there were no mortalities. At present, it is unclear if feeding antioxidants (in particular DHQ) at different levels, using different dietary formulations, and rearing birds under arange of environmental conditions may be effective at enhancing production performance and bird health in hot ambient climates.

Nutritional value of raw and micronised field beans (Vicia faba L. var. minor) with and without enzyme supplementation containing tannase for growing chickens.

An experiment examined the effects of two field bean cultivar samples with different tannin contents, the effect of heat treatment (micronising) and the effect of dietary supplementation of a proprietary enzyme preparation containing tannase, pectinase, and xylanase activities on metabolisable energy (ME), total tract dry matter digestibility (DMD) and ether extract digestibility (EED), nitrogen retention (NR), tannin degradability, gastrointestinal tract (GIT) development, and endogenous mucin losses excretion in broiler chickens. The Control diet contained per kg 221 g crude protein and 12.83 MJ ME. Four additional diets contained 300 g/kg of each of the two untreated or micronised experimental field bean cultivar samples. Each diet was then split into two batches and one of them was supplemented with 3400 units tannase per kg diet resulting in 10 diets in total. Each diet was fed to seven pens with two randomly selected male broilers each. Birds fed the high tannin bean sample had a lower weight gain (p < 0.001), and a lower determined apparent ME (p < 0.05), and DMD (p < 0.001) but a higher tannin degradability (p < 0.001). Compared to the Control diet, feeding field beans increased (p < 0.001) the weights of the proventriculus and gizzard of the birds, and also increased endogenous mucin losses (p < 0.05). Supplementing diets with the tannase-containing enzyme preparation improved dietary ME (p < 0.001), DMD (p < 0.001), NR (p < 0.001) and DEE (p < 0.05), but did not change tannin degradability. Heat treatment of the beans reduced the degradability of condensed tannins and increased endogenous mucin losses (p < 0.05). The differences in the feeding value of the different field bean samples were not improved by heat treatment, but enzyme supplementation improved the feeding value of all diets regardless of the bean samples or heat treatment. Further research is warranted to study the effectiveness of tannase supplementation in poultry diet formulations by dose response trials with purified tannase preparations.