Temporal dynamics of nutrient balance, plasma biochemical and immune traits, and liver function in transition dairy cows

The objective of this study was to analyze the dynamics of nutrient balance,physiological biomarkers and comprehensive indexes associated with metabolism and function of organs in transition cows.Fourteen transition cows were used for this research.Dietary intake was recorded daily,and samples of the diet,venous blood and milk were collected for measurements.The balance values of net energy for lactation(NEL),metabolizable protein(MP),and metabolizable glucose(MG) were calculated,and regression analysis and calculation of comprehensive indexes were performed.Accordingly,the prepartum cows presented positive balances of NEL,MP,and MG,while severe negative balances were found during the postpartum period.Dynamic changes of energy metabolism,nutrient mobilization,liver function,anti-oxidative status and immune response,as indicated by blood biomarkers and modified comprehensive indexes,were out of sync with the calculated balance values,but they were closely related to the day relative to calving.Compared with the 21 d prepartum,the plasma concentrations of non-esterified fatty acids(NEFA) and β-hydroxybutyric acid(BHBA) were significantly increased around and after calving(P<0.05),and similar variation tendency was observed for most of other parameters.The occurrence of parturition and the initiation of lactation were more responsible for the negative balances of nutrients in transition dairy cows.Although negative balances of NEL,MP and MG were not observed using the assessment model,the nutritional strategies should be applied before calving,because metabolic adaptations had been validated during the prepartum period.In addition,it was plausible to conclude that the decline of hepatic metabolism,defense function and insulin sensitivity are critical causes of metabolic dysfunction.

Occurrence of retained placenta is preceded by an inflammatory state and alterations of energy metabolism in transition dairy cows

Background： Failure to expel fetal membranes within 24 h of calving is a pathological condition defined as retained placenta（RP）. The objective of this investigation was to evaluate whether there are alterations in several selected serum variables related to innate immunity and carbohydrate and lipid metabolism that precede occurrence of RP in transition Holstein dairy cows.Methods： One hundred multiparous Holstein dairy cows were involved in the study. Blood samples were collected from the coccygeal vein during the-8 to ＋4 wks around parturition, once per week before the morning feeding.Six healthy control cows（CON） and 6 cows with RP were selected and serum samples at-8,-4, time of diagnosis of disease, and ＋4 wks relative to parturition were used for analyses. All samples were analyzed for lactate, nonesterified fatty acids（NEFA）, β-hydroxybutyrate（BHBA）, interleukin-1（IL-1）, interleukin-6（IL-6）, tumor necrosis factor（TNF）, haptoglobin（Hp）, and serum amyloid A（SAA）.Results： Cows with RP had greater concentrations of serum lactate, IL-1, IL-6, TNF, and SAA in comparison with CON cows. Intriguingly, elevated concentrations of all five variables were observed at-8 and-4 wks before the occurrence of RP compared to healthy cows. Cows with RP also had lower DMI and milk production vs CON animals; however milk composition was not affected by RP.Conclusions： Cows with RP showed an activated innate immunity 8 wks prior to diagnosis of disease. Overall results suggest that serum IL-1, IL- 6, and TNF, and lactate can be used as screening biomarkers to indicate cows that might have health issues during the transition period.

Supplementing N-carbamoylglutamate in late gestation increases newborn calf weight by enhanced placental expression of mTOR and angiogenesis factor genes in dairy cows

The objective of this study was to investigate whether supplementation with N-carbamoylglutamate(NCG)to cows during late gestation alters uteroplacental tissue nutrient transporters,calf metabolism and newborn weight.Thirty multiparous Chinese Holstein cows were used in a randomized complete block design experiment.During the last 28 d of pregnancy,cows were fed a diet without(CON)or with NCG(20 g/d per cow).The body weight of calves was weighed immediately after birth.Placentome samples were collected at parturition and used to assess mRNA expression of genes involved in transport of arginine,glucose,fatty acid and angiogenesis factors,as well as the mammalian target of rapamycin(mTOR)pathway.Blood samples of calves before colostrum consumption were also collected for the detection of plasma parameters,amino acids(AA)and metabolomics analysis.The newborn weight(P=0.02)and plasma Arg concentration of NCG-calves was significantly higher(P=0.05)than that of CON-calves,and the plasma concentrations of urea nitrogen tended to be lower(P=0.10)in the NCG group.The mRNA abundance of genes involved in glucose transport(solute carrier family 2 member 3[SLC2 A3],P<0.01),angiogenesis(nitric oxide synthase 3[NOS3],P=0.02),and mTOR pathway(serine/threonine-protein kinase 1[ACT1],P=0.10;euka ryotic translation initiation factor 4 B pseudogene 1[EIF4 BP1],P=0.08;EIF4 EBP2,P=0.04;and E74-like factor 2[ELF2],P=0.03)was upregulated in the placentome of NCG-supplemented cows.In addition,17 metabolites were significantly different in the placentome of NCG-supplemented cows compared to non-supplemented cows,and these metabolites are mainly involved in arginine and proline metabolism,alanine,aspartate and glutamate metabolism,and citrate cycle.In summary,the increased body weight of newborn calves from the NCG supplemented dairy cows maybe attributed to the increased angiogenesis and uteroplacental nutrient transport and to the activated mTOR signal pathway,which may result in the increased nutrient supply to the fetus,and improved AA metabolism and urea cycle of the fetus.