| Rumen-protected glucoseis a kind of glucose encapsulated to provide metabolic glucose for ruminants.Supplementation with rumen-protected glucose in the diet of ruminants can significantly improve their production performance,daily weight gain,and alleviate heat stress.However,there have been no reports on the addition of rumen-protected glucose to the entire perinatal period in dairy cows.Therefore,this study investigated the effects of adding rumen-protected glucose to the diet on the production performance,serum biochemical indicators,and placental lipid metabolism of dairy cows during the perinatal period.The aim was to provide experimental evidence and theoretical guidance for the development and utilization of rumen-protected glucose additives in dairy cow production.Test 1: Rumen degradation rate determination of rumen glucoseThree Holstein cows equipped with permanent fistulas were selected to verify the rumen rate of RPG,using the nylon bag method,about 3 g of RPG samples were weighed into a nylon bag,and iron was added into the rumen of the cow,the time points were set to0.5 h,1 h,3 h,5 h,8 h,12 h and 16 h,each fistula Holstein cow had 3 replicates per time point,a total of 9 replicates,1 sample per replicate,taken out when the recording time reached the corresponding point,rinsed and dried and weighed.The degradation rate of RPG at different time points in the rumen was calculated to calculate the rumen degradation rate and the rumen rate.The test showed that the rumen degradation rate of rumen glucose was 23.8%,while the actual rumen rate was 76.2%.Experiment 2: Effects of rumen glucose on perinatal dairy cow production performance,blood biochemical indexes and placental lipid metabolismThirty Holstein cows with a parity of 3.2 ± 0.1 litres and a weight of 720 ± 13.5kg were selected and randomly divided into three treatment groups as follows: control group(CON),fed basal diet + 200 g palmitic acid(coating);Test I(T200)added 100 g palmitic acid + 200 g RPG to the basal diet;Trial II group(T400)added 400 g of RPG to the basal diet with 10 replicates per treatment of 1 cow per replicate.The average daily feed intake and lactation of cows in each treatment group were recorded and counted,and the apparent digestibility of milk components and nutrients was determined.Taking calving time as day 0,blood from days-21,0,3,7 and 21 was collected and serum was isolated to measure hormonal indicators related to serum biochemistry and energy metabolism.The placenta was collected on the day of calving and stored in liquid nitrogen for placental transcriptome assay analysis.The pre-test period is 7 days,and the formal trial period is 42 days.The results of the study showed that:(1)The addition of RPG to feed had no significant effect on feed intake and apparent digestibility of nutrients in perinatal dairy cows.Compared with the CON group,milk production was significantly increased in the T200 group(P<0.05),and the milk fat rate in the T200 and T400 groups was significantly reduced(P<0.05)and lactose rate was significantly increased(P<0.05).(2)Compared with the CON group,the serum levels of glucose,insulin and leptin in the T200 and T400 groups were significantly increased(P<0.05),and the levels of total cholesterol,triglycerides and β-hydroxybutyric acid in serum were significantly reduced(P<0.05).(3)Placental transcriptome analysis revealed that compared to the control group,the T200 group showed upregulation of 188 genes and downregulation of 953 genes,while the T400 group showed upregulation of 870 genes and downregulation of 291 genes.KEGG enrichment analysis of these differentially expressed genes identified several pathways,including protein digestion and absorption,complement pathway,PI3K-Akt signaling pathway,and fatty acid elongation.GO enrichment analysis indicated enrichment of functions primarily related to immune function,nutrient transport,and animal organ development.Key differentially expressed genes potentially associated with calf growth and development were identified,including ATP1A2,SLC25A31,SLC8A2,SLC25A31,ADCY5,CYTH4,GATM,and PIK3R5.In summary,the addition of rumen-protected glucose(RPG)in the diet can improve the production performance of peripartum dairy cows,inhibit fat mobilization,alleviate negative energy balance,and contribute to the overall health of cows during the peripartum period.Furthermore,the inclusion of RPG in the prepartum diet may also promote the growth and development of calves. |
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