Effects of Dietary Supplementation of Zinc Oxide Quantum Dots on Growth Performance and Gut Health in Broilers.

This study aims to investigate the effect of different levels of zinc oxide quantum dots (ZnO-QDs) on the growth performance and gut health in broilers. A total of 1125 1-day-old Ross 308 broilers were randomly divided into five groups with 15 replicates of 15 chicks each. The broilers were fed basal diets supplemented with 0, 40, 80, 120, or 160 mg Zn/kg as ZnO-QDs for 6 weeks. The results showed that dietary 80 and 120 mg Zn/kg ZnO-QD supplementation increased (P < 0.05) average daily gain (1.4-1.7%) and reduced feed conversion ratio (1.3%) compared to the basal diet group during various experimental periods. Meanwhile, 80 mg Zn/kg ZnO-QD supplementation increased (P < 0.05) trypsin activity (25.4%), villus height, and the ratio of villus height to crypt depth in the jejunum. Moreover, 80 mg Zn/kg ZnO-QD supplementation increased (P < 0.05) the activities of glutathione reductase (47.7%) and superoxide dismutase (30.9%), while 120 mg Zn/kg ZnO-QD supplementation decreased (P < 0.05) glutathione peroxidase activity (27.1%) in the jejunum. Furthermore, 40 mg Zn/kg ZnO-QD supplementation down-regulated (P < 0.05) the expression of genes; interleukin-2, transforming growth factor ß (TGF-ß), Cathelicidin-1, Cathelicidin-2, Cathelicidin-3, and Occludin, while 80-160 mg Zn/kg ZnO-QD supplementation up-regulated (P < 0.05) Claudin-2 expression in the jejunum. In conclusion, dietary ZnO-QD supplementation improved growth performance of broilers potentially by enhancing their intestinal health status. Based on nonlinear regression analysis, the appropriate level of ZnO-QD supplementation would be from 98.2 to 102.5 mg Zn/kg.

Keratinase improves the growth performance, meat quality and redox status of broiler chickens fed a diet containing feather meal.

The objective of this study was to assess the effects of dietary supplementation of keratinase on the production of broilers fed a diet containing feather meal. A total of 162 1-d-old Cobb 500 male broiler (n = 9 cages/diet with 6 chicks/cage) were randomly allocated to 3 dietary treatments. The broilers were fed a corn-soybean-feather meal based diet (BD), or BD supplemented with keratinase at 100,000 or 200,000 U/kg for 6 weeks. Compared to the control, dietary supplementation with 200,000 U/kg keratinase increased (P < 0.05) body weight gain (3.6-4.3%) and reduced feed conversion ratio (2.4-5.6%) during the various experimental periods, and also improved (P < 0.05) apparent total tract digestibility of ash and calcium by 45.0% and 8.8%, respectively. Meanwhile, dietary supplementation of keratinase at 100,000 U/kg reduced (P < 0.05) the drip loss (29.2%), while 200,000 U/kg keratinase supplementation increased (P < 0.05) the pH value (1.6%) at 45 min and decreased (P < 0.05) the lightness (L* value; 13.6%) and drip loss (22.1%) of pectoral muscle. Moreover, dietary supplementation of keratinase at both levels of 100,000 and 200,000 U/kg increased (P < 0.05) Glutathione peroxidase activity (82.5-87.5%) and decreased the Malondialdehyde concentration (14.5-18.3%) in the pectoral muscle. In conclusion, dietary supplementation of keratinase at 200,000 U/kg can improve the performance, meat quality, apparent total tract digestibility of nutrients, and redox status of broiler chickens fed a diet containing feather meal.