| Due to major physiological stresses such as dry milk,labour and lactation,cows in the late perinatal period experience a decrease in dry matter intake(DMI),while lactation and maintenance require a large amount of energy,and therefore cows in the late perinatal period often experience a physiological state of negative energy balance(NEB).Excess NEFA can lead to metabolic disorders such as fatty liver and ketosis,increasing unnatural culling and costs to the cow.It is therefore particularly important to reduce fat mobilisation and alleviate the NEB status of cows in the late perinatal period.Propionate is a safe and reliable food and feed additive that is a metabolic end product of rumen fermentation in dairy cows.Sodium propionate(NaPr)can be a good additive for periparturient dairy cows for glucose xenobiotic production and is also a safe mould inhibitor with advantages not found in other feed additives.However,little is known about the effects of supplemental sodium propionate on cows in the late peripartum period.Therefore,it is important to study the effects of supplemental sodium propionate on the performance,serum biochemistry and lipid metabolism of dairy cows in the late periparturient period for the health and sustainable development of the dairy industry in China.1.Effect of NaPr in the diet on performance of cows in the late peripartum periodTo investigate the effect of sodium propionate on the performance of cows in the late perinatal period,24 cows with similar prepartum and body condition were divided into a control group(basal diet)and a sodium propionate group(basal diet+246 g NaPr)and fed for three weeks.The results showed that the addition of NaPr to the diet did not affect DMI and milk yield in late-periparturient cows compared with the control group(P>0.05)and trended towards higher lactose rates(P=0.07).In conclusion,supplementing cows with sodium propionate in the periparturient period is effective in improving milk quality.2.Effect of NaPr in the diet on glycolipid metabolites in late periparturient cowsTo investigate the effect ofNaPr on the glycolipid metabolism of cows in the late perinatal period,blood was collected from the tail vein and examined for indicators related to liver function,kidney function,glycolipid metabolism,immunoglobulins and antioxidants,and the results showed that the addition of NaPr to the diet significantly reduced the plasma content of alkaline phosphatase compared with the control group(P=0.01)and did not affect other indicators of liver and kidney function.Dietary addition of NaPr significantly increased glucose content(P<0.001)and trended to increase plasma triglycerides(P=0.05)and insulin content(P=0.07),without affecting other indicators of glucolipid metabolism.Dietary addition of NaPr decreased the level of immunoglobulin M(P=0.04)and did not affect other immunoglobulin and antioxidant indices.Dietary addition of NaPr significantly reduced plasma levels of NEFA(P=0.011)and did not affect BHBA levels compared to the control group.In conclusion,NaPr was effective in alleviating the NEB status of cows in the late perinatal period.3.Effect of NaPr in the diet on lipid metabolism in late periparturient cowsTo investigate the effect of NaPr on lipid metabolism in late-periparturient cows,laboratory measurements of triglyceride content,fatty acid composition and mRNA expression of key lipid metabolism genes were taken from live adipose tissues of late-periparturient cows.)and inhibited the oxidative breakdown of fatty acids.The addition of NaPr to the diet significantly down-regulated the expression of adipocyte endoplasmic reticulum stress-related genes in adipose tissue of periparturient cows(P<0.05)and also promoted the expression of fatty acid synthesis-related genes Acetyl-CoA carboxylase alpha(ACCa),Acyl-CoA synthetase short chain family member 2(ACCα)and Acyl-CoA synthetase short chain family member 2(ACCα).synthetase short chain family member 2(ACSS2)and acyl-CoA synthetase long chain family member 3(ACSL3)(P<0.05).In conclusion,NaPr helped to reduce fat mobilisation and increase fatty acid synthesis in cows during the periparturient period,thereby improving the metabolic function of adipose tissue.In summary,the addition of NaPr to the diet can improve milk quality,reduce fat mobilisation and increase fatty acid synthesis in periparturient cows,thereby improving the metabolic function of their adipose tissue and effectively alleviating their NEB status in the periparturient period. |
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