Nicotinamide Regulates Oxidative Stress In Dairy Goats During The Transition Period

Ruminants will be in a state of negative energy balance and a large amount of free fatty acids enter the liver for metabolism in order to provide energy for animals during the perinatal period.A large number of oxygen free radicals will be produced during the process of oxidation,which will induce oxidative stress and cause the inflammatory reaction,finally leading to cell damage.Nicotinamide(NAM),an amide form of niacin,as a precursor of NAD+ and NADP+,has the ability to transfer hydrogen and is involved in many oxidative stress pathways.At present,the effect and mechanism of NAM on the oxidative stress of perinatal ruminants are not clear.In this study,15 dairy goats were selected and divided into 3 treatment groups(5 replications for each group,1 for each repetition).NAM(5 g/d)was supplemented for the Entire group(from prenatal 21 d to postpartum 28 d)and Post group(from parturition to postpartum 28 d)respectively.All goats were slaughtered on postpartum 28 d.The results showed that: 1)The antioxidant enzymes activity and the content of oxidation products in serum varied along with time;more intense changes were found before and after parturition.SOD activity reaches their lowest levels parturition during the groups and increased significantly in POST than other groups(P = 0.035).A significant effect of time of sampling x feeding NAM interaction was noted(P = 0.017).From-14 d to 0 d relative to kidding,SOD was not affected during three groups(P > 0.05),it has shown the higher values in POST after delivery(P = 0.017).Goats supplemented for ENTIRE with NAM,CAT activity were higher than it in the CON and POST group.With the approaching of the parturition,the activity of CAT increased obviously and reached the highest value kidding.The effect of time of sampling x feeding NAM interaction was not observed during the experiment,a trend was noted during entire and postpartum period(P = 0.065).Over the whole period,CAT activity was significantly affected by treatments(P < 0.01).A trend increases of GSH-PX activity was noted in POST(P = 0.067).The time effect was observed over the entire period on serum CAT/SOD and GSH-PX/SOD.The change of CAT/SOD and GSH-PX/SOD are the same as CAT and GSH-PX activity.However,a trend increases of GSH-PX/SOD activity was noted in ENTIRENAM could improve the antioxidation capacity by increasing serum antioxidant enzymes activity in postpartum.Compared with the Control and Post groups,it was lower that the accumulation of hydrogen peroxide in the Entire group in postpartum.2)The content of valeric acid was lower and a trend reduces of acetic acid content was noted in POST and ENTIRENAM,however the content of propionic acid was significantly increased by supplementing NAM.2)Total hepatic antioxidant capacity in the Entire group was higher,and hepatic SOD1 expression was also up-regulated compared with Control group.The specific value between acetic acid and propionic acid was significantly influence.3)The results of hepatic oxidative electronic respiratory chain showed that supplement NAM to Entire group significantly increased the content of nicotinamide adenine dinucleotide(NADH)and mitochondrial complex enzymes,and trend to increase the yield of adenosine triphosphate(ATP),indicating that NAM entered into the liver in the form of NADH and accelerated the efficiency of electronic respiratory chain transferring.4)In mammary glands,there was no difference in the activity of antioxidant enzymes,while the supplement of NAM up-regulated GPX4 expression and reduced the accumulation of malondialdehyde.In conclusion,the oxidative stress of dairy goats was significantly changed during peripartum period.The supplement of NAM could improve the antioxidation capacity and relieve energy negative balance of dairy goat by accelerating the removal of hepatic oxygen free radicals and increasing the efficiency of oxidation.Supplementing NAM to Entire group developed best effects among three groups in the current study.