Effects of different formulations of α-tocopherol acetate (vitamin E) on growth performance, meat quality and antioxidant capacity in broiler chickens.

The objective of this study was to investigate and compare the effects of α-tocopherol acetate (vitamin E (VE)) and microencapsulated VE (MVE) on growth performance, meat quality and antioxidant capacity in broiler chickens. A total of 360 d-old broiler chicks were procured and randomly allocated into three groups with 6 replicates. Each replicate had 20 chickens. Chickens were fed with basal diets (CON group) or experimental diets supplemented with 20 mg/kg VE (VE group) or 20 mg/kg MVE (MVE group) for 42 d. The results showed that the MVE group had higher body weight gain (BWG) than the CON and VE groups, and higher gain/feed ratio (G/F ratio) than the CON group during the period of 22-42 d. During the whole experiment, a higher increase in BWG was found in the MVE group than the CON group. Chickens fed on diets supplemented with the VE or MVE had lower abdominal fat percentage, higher pH and antioxidant enzyme activity than the CON group in the breast meat. There was an increased tendency in the hepatic glutathione peroxidase (GSH-Px) enzyme activity of the VE and MVE groups than the CON group. The hepatic mitochondrial total antioxidant capacity and GSH-Px enzyme activity in the MVE group were higher than the CON group. Hepatic 2,2-dipheny-ʟ-picrylhydrazyl scavenging activity of the MVE group was higher than the CON group. These results suggested that the dietary addition of VE or MVE could improve breast meat quality in broilers. MVE supplementation may improve growth performance, hepatic mitochondrial antioxidant capacity and free radical scavenging capacity in chickens. In addition, dietary supplementation of MVE gave better broiler growth performance than VE.

Dietary curcumin supplementation protects against heat-stress-impaired growth performance of broilers possibly through a mitochondrial pathway.

A total of 400 1-d-old Arbor Acres broiler chicks were raised at a recommended environmental temperature from d 1 to 20 (experimental day [ED] = ED1 to ED20). On ED21, the chicks were weighed and reallocated into 5 treatment groups, with 8 replicates of 10 birds each. The 5 treatment groups were as follows: the control group, in which chicks were housed at 22 ± 1°C and fed the basal diet, and the HS, HS-CUR50, HS-CUR100, and HS-CUR200 groups, in which chicks were housed at 34 ± 1°C for 8 h (0900-1700 h) and 22 ± 1°C for the rest time and fed the basal diet with 0, 50, 100, and 200 mg/kg curcumin, respectively. From ED21 to ED42, the heat treatment lasted for 20 consecutive days. The results showed that heat-stressed broilers had greater (P < 0.05) average head surface and rectal temperature on ED21 and ED42 than the non-heat-stressed broilers. Diets supplied with 50 and 100 mg/kg curcumin increased (P < 0.05) the G:F compared to the heat-stressed groups. Mitochondrial malondialdehyde levels, an index of lipid peroxidation, in the breast muscle were 15.15 and 9.09% higher (P < 0.05) in 50 and 100 mg/kg curcumin supplemented groups than that of the heat-stressed group, respectively. Curcumin supplementation (50, 100, and 200 mg/kg) increased (P < 0.05) mitochondrial glutathione content and glutathione peroxidase, glutathione S-transferase, and manganese superoxide dismutase activities compared to heat-stressed broilers. Curcumin supplementation (50, 100, and 200 mg/kg) resulted in a decrease (P < 0.05) of heat shock protein 70 mRNA levels in the breast muscle. The breast muscle mRNA expression of peroxisome proliferator-activated receptor γ coactivator 1α and nuclear respiratory factor 1 and 2 in heat-stressed groups was increased (P < 0.05) in response to dietary 100 mg/kg curcumin treatment. Additionally, when compared to the heat-stressed group, mitochondrial transcription factor A mRNA levels were increased (P < 0.05) by 17.64% in the 200 mg/kg curcumin supplemented group. In conclusion, dietary curcumin supplementation prevented heat-stress-impaired growth performance, possibly through improving the antioxidant defense system and enhancing the mitochondrial biogenesis.