Effects Of Different Levels Of 2-hydroxy-4-methylselenobutanoic Acid Supplementation On Meat Quality And Selenium Deposition Of Yellow Broilers

This study aimed to investigate the effects of different levels of new type organic selenium supplementation(2-hydroxy-4-methylselenobutanoic acid,SeO)on meat quality and tissues selenium deposition of yellow broilers.A total of 375 1-day-old broilers were randomly divided into 5 treatments,5 repeats in each treatment and 15 broilers per repeat.The birds were fed on soybean-corn basal diet supplied with 0.0 mg SeO/kg(control),0.2 mg SeO/kg,0.4 mg SeO/kg,0.6 mg SeO/kg and 0.8 mg SeO/kg.The trial lasted for 9 weeks and growth performance,meat quality,antioxidant capacity,selenium deposition,and the expression of meat quality related genes and selenoprotein encoding genes in tissues were investigated.The main results are as following:1)The addition of different levels of dietary SeO had limited effect(P > 0.05)on growth performance of broilers.Except that 0.2 mg SeO/kg groups exhibited higher(P < 0.05)average daily gain(ADG)than that of the control group and other selenium addition groups at 6~9 weeks,and 0.2 mg SeO/kg and 0.6 mg SeO/kg groups had the lower(P < 0.05)F/G than that of other selenium addition groups and control groups at 0-3 weeks.2)Dietary SeO supplementation had no impact on breast muscle percentage of broilers.As for thigh muscle,compared with the control groups,0.2 mg SeO/kg and 0.4 mg SeO/kg addition increased(P > 0.05)thigh muscle percentage of yellow broilers,while 0.6 mg SeO/kg and 0.8 mg SeO/kg dietary SeO had a tendency to decrease(P > 0.05)thigh muscle percentage,and 0.2 mg SeO/kg group exhibited higher(P < 0.05)thigh muscle percentage than that of 0.6 mg SeO/kg group.Comapred with the control groups,low levels(0.2 mg SeO/kg and 0.4 mg SeO/kg)of SeO addition reduced(P > 0.05)the liver index of broilers,while high levels(0.6 mg SeO/kg and 0.8 mg SeO/kg)of SeO increased(P > 0.05)the liver index of broilers.0.8 mg SeO/kg group exhibited higher(P < 0.05)liver index than that of 0.2 mg SeO/kg and 0.4 mg SeO/kg groups.3)Dietary SeO addition effectively improved meat quality of yellow broilers.Compared with the control group,0.2 mg SeO/kg and 0.6 mg SeO/kg supplementation increased(P < 0.05)the pH 45 min value,0.6 mg SeO/kg and 0.8 mg SeO/kg addition increased(P < 0.05)the pH 24 h value of the breast muscle.The addition of different levels of SeO moderately reduced the shear force of the breast muscle and 0.8 mg SeO/kg group exhibited a lower(P < 0.05)shear force of the breast muscle.Dietary SeO supplementation reduced the peroxide value(TBARS)of the chest muscle at 2 d and 0.2 mg SeO/kg,0.4 mg SeO/kg and 0.8 mg SeO/kg groups exhibited a lower(P < 0.05)TBARS values.Although there are no significant effect of SeO on flesh color,cooking loss and driping loss at 24 h,the driping loss and cooking loss exhibited a decreasing tendency(P > 0.05)with the increasing levels of dietary SeO.4)Dietary SeO supplementation effectively improved anti-oxidant capacity in tissues of the yellow broilers.SeO increased(P < 0.05)the activities of GSH-Px in serum and thigh muscle,while had limited effect(P > 0.05)on activities of GSH-Px in liver.SeO supplementation decreased(P > 0.05)MDA concentration in values in serum,breast muscle,thigh muscle and liver.SeO had limited impact(P > 0.05)on activity of T-AOC in breast muscle and liver,while 0.6 mg SeO/kg and 0.8 mg SeO/kg increased(P < 0.05)the activities of T-AOC in serum and thigh muscle.Dietary SeO exhibited limited impact(P > 0.05)on the activity of T-SOD in serum,breast muscle,thigh muscle and liver.5)Compared with the control group,dietary SeO supplementation increased(P < 0.05)selenium concentration in in serum,breast muscle and thigh muscle of broilers.The new type of organic selenium(SeO)effectively improved selenium deposition in muscle tissues and the selenium deposition in breast muscle and thigh muscle exhibited a linear dose depend manner,0.2 mg SeO/kg and 0.4 mg SeO/kg dietary SeO could make the selenium deposition in muscles reach to the safe selenium-rich levels(0.2-0.5 mg Se/kg).6)Dietary SeO also exhibited impact on expression of genes related to meat quality in yellow broilers.Levels of SeO supplementation down-regulated(P < 0.05)expression of TNNT2,0.6 mg SeO/kg showed a tendency(P > 0.05)to decrease expression of TNNI2 while up-regulated(P < 0.05)FABP in breast muscle.Dietary SeO moderately up-regulated(P < 0.05)four quality-related genes(LPL,TNNI2,PPAR? and PPAR?)in a dose dependent manner in thigh muscle.Both levels of SeO addtion increased(P < 0.05)mRNA level of PRKAG3 and 0.4 mg SeO/kg group exhibited the highest mRNA levels in thigh muscle of broilers.7)Dietary SeO also exhibited impact on expression of selenoprotein encoding genes in tissues of yellow broilers and the response of expression of genes to dietary SeO exhibited different pattern in different tissues.In breast muscle,0.2 mg SeO/kg and 0.4 mg SeO/kg up-regulated(P < 0.05)mRNA level of(GPX1,GPX3,GPX4,SELENON,SELENOO,SEPHS2 and TXNRD2),0.2 mg SeO/kg,0.4 mg SeO/kg and 0.8 mg SeO/kg up-regulated(P < 0.05)mRNA level of DIO2.Dietary SeO moderately up-regulated expression of three genes(DIO3,SELENOU and SELENOW)in a dose dependent manner and 0.6 mg SeO/kg and 0.8 mg SeO/kg addition groups exhibited a higher(P < 0.05)mRNA profiles.SeO decreased(P < 0.05)expression of four selenoprotein encoding genes(SELENOI,SELENOK,SELENOS and SELENOT)in breast muscle.Dietary SeO up-regulated(P < 0.05)mRNA level of 13 selenoprotein encoding genes in thigh muscle,and 7 genes(DIO1,DIO2,DIO3,SELENOM,SELENOK,SELENON and SELENOS)were up-regulated in a dose depend manner,and 6 genes(GPX4,SELENOF,SELENOT,SELENOU,SELENOW and TXNRD1)were up-regulated when SeO were supplied at levles of 0.4 mg SeO/kg and 0.6 mg Se/kg.It is strange that dietary SeO addition down-regulated(P < 0.05)expression of fifteen selenoprotein genes(DIO1,DIO2,GPX4,MASBR1,SELENOF,SELENOK,SELENOM,SELENON,SELENOO,SELENOS,SELENOW,SEPHS2,TXNRD1,TXNRD2 and TXNRD3)in liver.Conclusion: Dietary supplementation of new type of organic selenium(2-hydroxy-4-methylselenobutanoic acid,SeO)improves the meat quality of yellow broilers and enhanced the anti-oxidant capacity in tissues of broiler,those improvements effects is associated with regulation expression of meat quality-related genes and selenoprotein encoding genes in corresponding tissues;(2)The new type of organic selenium(SeO)effectively improved selenium deposition in muscle tissues and the muscle selenium deposition exhibited a linear dose depend manner,0.2 mg SeO/kg and 0.4 mg SeO/kg dietary SeO could make the selenium deposition in muscles reach to the safe selenium-rich levels(0.2-0.5 mg Se/kg).