Rumen-protected Glucose Research Articles

Effect of Rumen-Protected Glucose Supplementation on Feedlot Performance, Carcass Characteristics, and Meat Quality of Kamphaeng Saen Steers

Effect of Rumen-Protected Glucose Supplementation on Feedlot Performance, Carcass Characteristics, and Meat Quality of Kamphaeng Saen Steers

Rumen-protected glucose stimulates the secretion of reproductive hormones and the mTOR/AKT signaling pathway in the ovaries of early postpartum

This study was conducted to determine the response of the reproductive hormones and the mTOR/AKT/PI3K pathway in the ovaries of postpartum dairy cows with dietary rumen-protected glucose (RPG). Twelve Holstein cows were randomly assigned to two groups (n = 6/group): the control group (CT) and the RPG group. Blood samples were collected on d 1, 7, and 14 after calving for the gonadal hormone assay. The expression of the gonadal hormones receptors and PI3K/mTOR/AKT pathways were detected using RT-PCR and Western blot. The RPG addition increased the plasma LH, E2, and P4 concentrations on d 14 after calving and upregulated the mRNA and protein expressions of the ERα, ERβ, 17β-HSD, FSHR, LHR, and CYP17A1 but downregulated StAR expression. Immunohistochemical analysis identified higher expressions of the FSHR and LHR in the ovaries of RPG-fed cows compared to CT cows. Furthermore, the protein expressions of p-AKT/AKT and p-mTOR/mTOR were significantly increased in the ovaries of RPG-fed cows compared to the CT group, but the addition of RPG did not alter the protein expression of p-PI3K/PI3K. In conclusion, the current results indicated that dietary RPG supplementation regulated gonadotropin secretion and stimulated expression of hormone receptors and the mTOR/AKT pathway in the ovaries of early postpartum dairy cows. RPG may be beneficial for the recovery of ovarian activity in post-calving dairy cows.

Effects of fresh-cow grouping strategy and rumen-protected glucose on production performance, reproductive variables and risk of culling in Holstein cows.

The interaction effects of duration of stay in fresh-cow diet and supplementation with rumen-protected glucose (RPG) on productivity of dairy cows are largely unknown. We hypothesised that a faster transition from fresh-cow diet (higher forage:concentrate) to lactation-cow diet (lower forage:concentrate), combined with supplementation of fresh-cow diet with RPG will have positive effects on production and health of dairy cows. To investigate the immediate and long-term effects of length of stay in fresh-cow diet and supplementation with RPG on productive and reproductive performance of high-producing dairy cows. A total of 264 multiparous Holstein cows (average parity ± standard deviation = 3.2± 1.3, ranging from 2 to 6) were used in a 2 × 2 factorially arranged trial. Treatments were the feeding duration of a fresh-cow diet for 14 or 21 days, each combined by daily supplementation of the fresh-cow diet with ground corn grain or RPG product top dressed at 500g/day/head. The earlier transition from fresh-cow to lactation diet resulted in greater milk production from 15 through 21 days in milk (DIM; by 2.28kg/day), and also fat-corrected milk production on 30 and 60 DIM, respectively. Corn grain or RPG supplementation did not affect the average milk production (1 to 21 DIM), as well as milk production and composition on 30 and 60 DIM. Although extent of body condition loss at transition tended to be lesser in cows switching faster to lactation diet, these cows lost more body condition from 30 to 90 DIM. Survival analysis on calving-to-conception interval and time to removal from herd did not find any significant difference across treatments. The positive effects of earlier transition from fresh-cow to lactation diet were evident by greater milk production from 15 through 21 DIM, and fat-corrected milk production (30 and 60 DIM), at the expense of body condition in high-producing dairy cows. A daily topdress of RPG on fresh-cow diet had no immediate or carryover effects on production of dairy cows.

Rumen-protected glucose hastens uterine involution and increases numbers of ovarian follicles in early post-partum dairy cows.

The primary objectives were to investigate the effects of feeding a new rumen-protected glucose (RPG) on uterine involution and ovarian follicular dynamics in recently calved dairy cattle. From 4 to 30 days after calving, 16 Holsteins (first to third lactation, mean parity 1.75) were randomly assigned to be fed either a basal diet top-dressed with either 600 g RPG (RPG group) or 600 g of the coating material and glucose (CONT group). Based on transrectal ultrasonography, conducted every 3 days starting 20 days after calving, the interval from calving to complete uterine involution was shorter in RPG versus CONT (27.1 vs. 30.4 days, p < .01). Furthermore, based on transrectal ultrasonography conducted every 2 days, cattle fed RPG had smaller (3.0-4.9 mm) ovarian follicles (2.96 vs. 0.9, p < .001) and more total follicles (5.26 vs. 2.85, p < .01). Feeding RPG had increased serum insulin concentrations (4.59 ± 0.54 vs. 3.13 ± 0.57, p < .05), but had no significant effects on serum glucose concentrations, dry matter intake or milk yield. In conclusion, we inferred that cattle fed RPG had increased glucose turnover that was responsible for higher insulin concentrations, faster uterine involution, and more ovarian follicles.

Rumen-protected glucose supplementation alters fecal microbiota and its metabolic profiles in early lactation dairy cows.

Negative energy balance (NEB) is the pathological basis of metabolic disorders in early lactation dairy cows. Rumen-protected glucose (RPG) is a feed additive to relieve NEB of cows in early lactation. The aims of the current study were to evaluate the impact of different doses of RPG supply on fecal microbiota and metabolome in early lactation dairy cows, and their correlation with each other. A total of 24 multiparous Holstein dairy cows in early lactation were randomly assigned to one of four treatments for the first 35 days of the early lactation period, as follows: control group, a basal diet without RPG (CON); low RPG, a basal diet plus 200 g/d RPG (LRPG); medium RPG, a basal diet plus 350 g/d RPG (MRPG); or HRPG, high RPG, a basal diet plus 500 g/d RPG (HRPG). After 35 days, fecal samples were obtained from cows in all groups individually and using 16S rRNA gene sequencing to evaluate their microbiotas, while their metabolites were evaluated through metabolomics. As expected, Firmicutes and Bacteroidetes were the core bacteria phyla. After RPG supplementation, there were an increase in Firmicutes and a decrease in Bacteroidetes. MRPG increased the relative abundance of cellulolytic bacteria, including Ruminococcaceae_UCG-005, Lachnospiraceae_UCG-008, Lachnospiraceae_FCS020_group, and Ruminiclostridium_9, while it decreased the relative abundance of Alistipes, Prevotellaceae_UCG-003, and Dorea. RPG supplementation could regulate the carbohydrate metabolism and amino acid metabolism pathway significantly and relieve lipolysis in dairy cows. Correlation analysis of fecal microbiome and metabolome showed that some major differential bacteria were the crucial contributors to differential metabolites. In conclusion, RPG supplementation can affect the fecal microbial components and microbial metabolism, and 350 g RPG might be the ideal dose as a daily supplement.

Supplementation of Rumen-Protected Glucose Increased the Risk of Disturbance of Hepatic Metabolism in Early Postpartum Holstein Cows.

The dual stress of reduced feed intake and increased milk yield in dairy cows early postpartum results in a negative energy balance. Rumen-protected glucose (RPG) has been reported to replenish energy, increase milk yield, and improve gut health. However, early postpartum cows often develop an insulin resistance, implying that RPG may not be well utilized and increased milk production may increase the liver’s fat oxidization burden. This study aimed to investigate the effects of RPG on the hepatic oxidative/antioxidative status and protein profile. Starting 7 d before expected calving, six pairs of cows were supplemented with rumen-protected glucose (RPG, n = 6) or with an equal amount of rumen-protecting coating fat (CON, n = 6). Liver samples were obtained from 10 cows 14 d after calving (d 14). Concentration of malondialdehyde and activity of glutathione peroxidase were increased and the activities of catalase and superoxide dismutase tended to increase in the livers of the RPG cows compared to the CON cows. The revised quantitative insulin sensitivity check index (RQUICKI) was decreased by RPG, but triacylglycerol concentration in liver was increased by RPG supplementation. The overall profiles of hepatic proteins were similar between CON and RPG. A partial least square regression was conducted to identify the proteins associated with liver lipidosis, oxidative stress, and antioxidative capacity. The top twenty proteins, according to their variable importance value, were selected for metabolic pathway enrichment analysis. Eighteen enriched KEGG pathways were identified, including metabolism, the citrate cycle, propanoate metabolism, the peroxisome, and type II diabetes mellitus. Our study showed that RPG supplementation reduced insulin sensitivity but increased the liver triglyceride concentration and the oxidative stress in early postpartum cows. Liver proteins related to lipidosis, oxidative stress, and antioxidative capacity, were positively associated with the glutamine metabolism, citric acid cycle, peroxisome, and type II diabetes pathways, which may indicate an increased risk of liver metabolic disorders caused by RPG supplementation in early postpartum cows.

​Effects of Rumen-protected Glucose Supplementation on Growth Performance, Body Measurements and Plasma Biochemical Indices of Fattening Chinese Simmental Bulls

Background: The objective of the study was to investigate the effects of rumen-protected glucose (RPG) supplementation on growth performance, body measurements and plasma biochemical indices of Simmental bulls in Northeast China during the fattening period. Methods: A 90 d feedlot study was conducted using thirty Simmental bulls (body weight = 444.3±26.9 kg). Bulls were randomly allocated into three groups to receive a basal total mixed ration (TMR) supplemented daily with 0 g RPG (control, Con), 100 g RPG (RPG100) or 300 g RPG (RPG300) per bull. Growth performance, body measurements and plasma biochemical indices were evaluated. Result: The greater ADG (P less than 0.05) and lower feed efficiency value (P less than 0.01) were found for bulls fed RPG compared to CON diet. Bulls fed RPG had increased body height and chest girth growth compared with CON diet (P less than 0.05). The plasma glucose (GLC) concentration was higher for bulls fed RPG300 diet than CON and RPG100 diets (P less than 0.01). Nonestesterified fatty acid (NEFA) concentration was lower for RPG compared with CON treatment (P less than 0.05). Our analysis suggests that a daily supplement of 300 g RPG is an effective way to increase the body’s total GLC provision and thus improve the growth performance of Simmental bulls during the fattening period.

Rumen-protected glucose supplementation in transition dairy cows shifts fermentation patterns and enhances mucosal immunity.

Manipulation of perinatal diets, such as supplementing feed with rumen-protected glucose (RPG), has been positively regarded as a strategy to improve milking performance. This study was conducted to assess the effects of RPG on the fermentation profiles, resident microbiota and mucosal immunity in the cecum. Ten Holstein dairy cows were randomly assigned to either a 25 g/kg RPG diet (DM basis) or a 11 g/kg coating fat diet (control, CON). Compared with the CON group, the acetate-to-propionate ratio was lower in the RPG group. Gene expression analysis indicated that RPG supplementation tended to upregulate the expression of Na+/H+ hydrogen exchanger 3 (NHE3) (P = 0.076). RPG supplementation downregulated the expression of genes involved in self-rehabilitation such as matrix metalloproteinase 1 (MMP1), MMP3, MMP9 and MMP13. Additionally, the mRNA expression of genes involved in immunity including Toll-like receptors (TLR4, TLR6 and TLR7) and proinflammatory cytokines (immune interferon gamma [IFNG] and interleukins interleukin 17A [IL17F], IL17A, IL22), was downregulated by RPG supplementation. Nonetheless, no differences existed in the bacterial copy number and beta diversity between the 2 groups. Overall, supplementation with RPG would probably cause a shift towards propionate production in the cecal digesta, and promote the immune homeostasis of the cecal mucosa in transition dairy cows. Our results extended the basic understanding of RPG supplementation and utilization in transition dairy cows in terms of host microbe interplay in the cecum.

Metabolomic changes in the liver tissues of cows in early lactation supplemented with dietary rumen-protected glucose during the transition period

A fat-coated rumen-protected glucose (RPG) product was used to meet the high energy requirements of transition-period cows. Twelve multiparous Holstein cows (age, 4–5 years; body weight, 515 ± 42 kg; milk yield, 16.1 ± 3.7 kg/d) were blocked by body weight, previous milk production, and calving date and were assigned to two groups: the control (CON) group and the RPG group. For treatment, the CON group was fed a basal diet plus 90 g of coating fat, and the RPG group was fed the basal diet supplemented with RPG at 200 g/d. The treatments were continued from 7 d before to 14 d after calving. Five cows from each group were humanely euthanized on day 14 after calving, and liver tissues were obtained. The liver samples were analysed using untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based global metabolomics to investigate potential hepatic metabolic mechanisms related to nutrient metabolism in cows in early lactation supplemented with RPG during the transition period. A total of 172 significantly differentially expressed metabolites between the RPG and CON groups were identified. Compared with the CON group, the RPG group exhibited a higher level of beta-D-glucose 6-phosphate (log2[fold change, FC]= 1.49, P = 0.018) and lower levels of riboflavin (log2FC = 0.64, P = 0.002), flavin mononucleotide (FMN; log2FC = 0.71, P = 0.034), L-tryptophan (log2FC = 0.83, P = 0.022) and L-serine (log2FC = 0.68, P = 0.034). The differentially expressed metabolites were significantly enriched in 18 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways (P < 0.05), including the riboflavin metabolism pathway, glucose metabolism pathways (glycolysis/gluconeogenesis, the pentose phosphate pathway), and amino acid metabolism pathways (tryptophan metabolism; glycine, serine and threonine metabolism). The results of the present study help create a comprehensive and detailed understanding of the hepatic metabolic responses of transitioning dairy cows to exogenous glucose. These results may improve our understanding of the metabolic impact and mechanisms of action of RPG in dairy cattle.

Ruminal Degradation of Rumen-Protected Glucose Influences the Ruminal Microbiota and Metabolites in Early-Lactation Dairy Cows.

Rumen-protected glucose (RPG) plays an important role in alleviating the negative energy balance of dairy cows. This study used a combination of rumen microbes 16S and metabolomics to elucidate the changes of rumen microbial composition and rumen metabolites of different doses of RPG's rumen degradation part in early-lactation dairy cows. Twenty-four multiparous Holstein cows in early lactation were randomly allocated to control (CON), low-RPG (LRPG), medium-RPG (MRPG), or high-RPG (HRPG) groups in a randomized block design. The cows were fed a basal total mixed ration diet with 0, 200, 350, and 500 g of RPG per cow per day, respectively. Rumen fluid samples were analyzed using Illumina MiSeq sequencing and ultrahigh-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. MRPG supplementation increased bacterial richness and diversity, including increasing the relative abundance of cellulolytic bacteria, such as Ruminococcus, Lachnospiraceae_NK3A20_group, Ruminiclostridium, and Lachnospiraceae_UCG-008 MRPG significantly increased the concentrations of acetate, propionate, butyrate, and total volatile fatty acid in the rumen. Ruminal fluid metabolomics analysis showed that RPG supplementation could significantly regulate the synthesis of amino acids digested by protozoa in the rumen. Correlation analysis of the ruminal microbiome and metabolome revealed some potential relationships between major bacterial abundance and metabolite concentrations. Our analysis found that RPG supplementation of different doses can change the diversity of microorganisms in the rumen and affect the rumen fermentation pattern and microbial metabolism and that a daily supplement of 350 g of RPG might be the ideal dose.IMPORTANCE Dairy cows in early lactation are prone to a negative energy balance because their dry matter intake cannot meet the energy requirements of lactation. Rumen-protected glucose is used as an effective feed additive to alleviate the negative energy balance of dairy cows in early lactation. However, one thing that is overlooked is that people often think that rumen-protected glucose is not degraded in the rumen, thus ignoring its impact on the microorganisms in the rumen environment. Our investigation and previous experiments have found that rumen-protected glucose is partially degraded in the rumen. However, there are few reports on this subject. Therefore, we conducted research on this problem and found that rumen-protected glucose supplementation at 350 g/day can promote the development and metabolism of rumen flora. This provides a theoretical basis for the extensive application of rumen bypass glucose at a later stage.

Metabolomics reveals effects of rumen-protected glucose on metabolism of dairy cows in early lactation

Early lactation dairy cows are vulnerable to negative energy balance (NEB) due to reduced dry matter intake (DMI) and high energy requirements for lactation. This study mainly revealed the mechanism of different doses of rumen-protected glucose (RPG) to alleviate NEB of the early lactating dairy cows through serum untargeted metabolomics, and explored the effects of different doses of RPG on rumen fermentation, lactation performance, and serum biochemical indices associated with NEB. Thirty-two multiparous Holstein cows in early lactation, blocked by parity, liveweight, and milk yield, were allocated to one of four treatments in a randomized block design. Treatments were: control (CON), low RPG (LRPG), medium RPG (MRPG) and high RPG (HRPG) with 0, 200, 350 and 500 g RPG per cow per day, respectively. Treatments were applied from calving to 35 days postpartum. The results showed that compared with other groups, the MRPG group changed the rumen environment, increased milk protein composition on 35 d, and decreased serum concentrations of β-hydroxybutyric acid (BHBA), non-esterified fatty acid (NEFA), aspartate aminotransferase (AST), and could increase glucose (GLU) concentration in serum. Dietary RPG supplementation affected ruminal pH and some volatile fatty acid (VFA) concentrations. The results of serum metabolomics showed that the metabolites with the largest contribution of the first 30 differences after RPG supplementation were mainly involved in lipid metabolism. The results of this study indicated that adding 350 g RPG to a cow’s diet in early lactation could improve energy balance by reducing fat mobilization.

Energetic metabolism, milk production, and inflammatory response of transition dairy cows fed rumen-protected glucose

Objectives were to evaluate the effects of rumen-protected glucose (RPG) supplementation on milk production, post-absorptive metabolism, and inflammatory biomarkers in transition dairy cows. Fifty-two multiparous cows were blocked by previous 305-d mature-equivalent milk (305ME) yield and randomly assigned to 1 of 2 iso-energetic and iso-nitrogenous treatments: (1) control diet (CON; n = 26) or (2) a diet containing RPG (pre-fresh 5.3% of dry matter and 6.0% of dry matter postpartum; n = 26). Cows received their respective dietary treatments from d -21 to 28 relative to calving, and dry matter intake was calculated daily during the same period. Weekly body weight, milk composition, and fecal pH were recorded until 28 d in milk (DIM), and milk yield was recorded through 105 DIM. Blood samples were collected on d -7, 3, 7, 14, and 28 relative to calving. Data were analyzed using repeated measures in the MIXED procedure (SAS Institute Inc., Cary, NC) with previous 305ME as a covariate. Fecal pH was similar between treatments and decreased (0.6 units) postpartum. Dry matter intake pre- and postpartum were unaffected by treatment, as was milk yield during the first 28 or 105 DIM. Milk fat, protein, and lactose concentration were similar for both treatments. Blood urea nitrogen and plasma glucose concentrations were unaffected by treatment; however, results showed increased concentration of circulating insulin (27%), lower nonesterified fatty acids (28%), and lower postpartum β-hydroxybutyrate (24%) in RPG-fed cows. Overall, circulating lipopolysaccharide-binding protein and haptoglobin did not differ by treatment, but at 7 DIM, RPG-fed cows had decreased lipopolysaccharide-binding protein and haptoglobin concentrations (31 and 27%, respectively) compared with controls. Supplemental RPG improved some biomarkers of post-absorptive energetics and inflammation during the periparturient period, changes primarily characterized by increased insulin and decreased nonesterified fatty acids concentrations, with a concomitant reduction in acute phase proteins without changing milk production and composition.

Physiologic responses to feeding rumen-protected glucose to lactating dairy cows

It was hypothesized that rumen-protected glucose (RPG) in diets of dairy cows increases concentrations of insulin resulting in greater blood progesterone concentrations because elevated insulin decreases activity of liver enzymes inactivating steroid hormones. Timing of ovulation was synchronized among 64 postpartum Holstein cows using GnRH and PGF2α (Day 0 = ovulation). Cows were milked thrice daily and assigned randomly a basal diet supplemented with 0, 1, 2, or 4 kg of an RPG product in place of corn grain, top-dressed in the diet beginning on Day -3. Blood was collected pre- and post-prandial on Days 0, 2, and 4 to determine plasma glucose and insulin concentrations and daily from Days 2 through 12. Intake of crude protein and energy-soluble carbohydrates increased linearly with dose, whereas starch intake decreased linearly with dose. Neither daily milk yield nor dry matter intake (DMI), energy-corrected milk (ECM), somatic cell count, or percentages of milk fat, protein and lactose on Day 8 differed among dietary treatments. Neither pre- nor post-prandial changes in plasma glucose differed among treatments. In contrast, post-prandial glucose decreased from Days 0 through 4. A change in plasma insulin (post-prandial minus pre-prandial) was detected. Milk urea nitrogen increased linearly with RPG dose. Concentrations of progesterone were unaffected by RPG dose. It is concluded that insulin response to RPG was decreased relative to the control and RPG supplementation linearly increased crude protein intake and milk urea nitrogen with increasing dose, but did not affect concentrations of progesterone, milk yield, or dry matter intake.

Rumen-Protected Glucose Stimulates the Insulin-Like Growth Factor System and mTOR/AKT Pathway in the Endometrium of Early Postpartum Dairy Cows.

Simple SummaryA rapid recovery of the uterus is important in order to shorten the interval between pregnancies. An insufficient availability of glucose in early lactation can delay the uterine recovery. However, little information is available on dietary rumen-protected glucose addition on the uterine involution and insulin-like growth factor system in the endometrium of dairy cows during the early post-natal period. In this study, dairy cows were fed with 0 or 200 g rumen-protected glucose twice every day from −7 ± 2 to 14 d during the post-natal period. The results indicated that dietary rumen-protected glucose addition promoted the proliferation of endometrial cells in postpartum dairy cows by stimulating the insulin-like growth factor system and rapamycin complex 1 pathway, and might be beneficial for uterine recovery. This study aimed to elucidate the effects of a dietary rumen-protected glucose (RPG) addition on uterine involution through the analysis of an insulin-like growth factor (IGF) system and associated pathways in the post-natal endometrium. Twelve Holstein cows were assigned equally to two groups: a control group (CT) and an RPG group (200 g of RPG per cow per day). The plasma content of insulin-like growth factor 1 (IGF1) was determined by using the ELISA method. Expressions of IGF members, the matrix metalloproteinase, protein kinase B (AKT)/mechanistic target of rapamycin complex1 (mTOR) signaling pathway, and cell proliferation factors (proliferating cell nuclear antigen (PCNA) and Ki67) were detected using real-time polymerase chain reaction, Western blot, immunohistochemistry, and immunofluorescence, respectively. The results showed that the positive cells of PCNA and Ki67 were increased in the endometrium of RPG versus CT cows. The RPG addition significantly increased the plasma IGF1 level 14 d after delivery. The mRNA expressions of the IGF family members (IGF1, IGF2, type 1 IGF receptor (IGF1R) and IGF-binding proteins (IGFBP1, IGFBP2, IGFBP4 and IGFBP5)) were upregulated, and mRNA expressions of matrix metalloproteinase MMP3 and MMP9 were downregulated in cows from the RPG group compared with the CT group. Meanwhile, the protein expressions of IGF1, IGF2, IGF1R, IGFBP1 and IGFBP4 were upregulated in cows from the RPG group compared with the CT group. Immunohistochemical analysis identified a positive response for IGF1R and IGF2R in the endometrium of RPG versus CT cows. Furthermore, the RPG supplementation increased the protein expressions of phosphorylated (p)-AKT to total AKT and p-mTOR to total mTOR ratio in the endometrium. The current results indicated that the RPG supplementation promoted the proliferation of endometrial cells by stimulating the IGFs and mTOR/AKT pathway in the early post-natal endometrium of dairy cows.

Effects of rumen-protected glucose on ileal microbiota and genes involved in ileal epithelial metabolism and immune homeostasis in transition dairy cows

Optimizing diet formula with the aim of alleviating negative energy balance (NEB) is of great significance to the production performance of transition dairy cows. The objective of the study was to evaluate the effects of rumen-protected glucose (RPG) supplementation on ileal microbiota, the expression of genes involved in epithelial metabolism and immune homeostasis in the ileum of transition dairy cows. Ten Holstein dairy cows (age, 4.7 ± 0.5 years; bodyweight, 515 ± 42 kg; parity, 2.8 ± 0.4; body condition score, 3.2 ± 0.3; milk yield, 16.1 ± 3.7 kg/d) were randomly divided into two groups. The treatments were a basal diet plus 200 g/d of RPG (450 g/kg of glucose, 450 g/kg of coating fat and 100 g/kg of water) or a basal diet plus 90 g/d of coating fat (CON). Cows were provided with the diets for 21 days (from 1 week prepartum to 2 weeks postpartum) and euthanized on d 22 for taking samples. The ileal digesta samples were taken from the mid-ileum to analyze volatile fatty acid concentration and composition of digesta-associated microbiota. The ileal mucosa samples were taken from the mid-ileum for analysis of gene expression and composition of mucosa-associated microbiota. Ileal total volatile fatty acid concentration was lower (P = 0.018) in the PRG-supplemented group than in the CON group. Compared with CON group, the PRG supplementation up-regulated or tended to up-regulate (P < 0.10) the expression of PC, SGLT3, IGFBP5, PPARA, IL10, Occludin, and TPJ1, but down-regulated the expression of IL17A (P = 0.032) and tended to down-regulate (P < 0.10) the expression of TLR4, TLR9 and IL26. However, no differences (P > 0.10) were observed between the RPG and CON groups in both ileal total bacterial copy number and ileal bacterial beta diversity. Collectively, dietary RPG supplementation promoted epithelial metabolism and improved immune homeostasis in the ileum, with no influence on both digesta- and mucosa-associated ileal microbiota of transition dairy cows.

Supplementation with fat-coated rumen-protected glucose during the transition period enhances milk production and influences blood biochemical parameters of liver function and inflammation in dairy cows

Supplementation of rumen-protected glucose (RPG) may be a useful dietary strategy to improve energy balance in transition dairy cows. The present study was performed to investigate whether supplementation with RPG could improve milk production and reduce inflammation or infection during the transition period in cows. Twelve Holstein cows (age, 4–5 yrs; bodyweight, 515 ± 42 kg; milk yield, 16.1 ± 3.7 kg/d)in late gestation were allotted to one of 2 treatments. The treatments were a basal diet plus 200 g/d of RPG (450 g/kg of glucose, 450 g/kg of coating fat and 100 g/kg of water) or a basal diet plus 90 g/d of coating fat (CON). Treatments were applied from 1 wk before to 2 wk after calving. Animal performance data were recorded, and the overall tract apparent digestibility of prepartum or postpartum cows was determined. Blood was sampled on d −4, 0, 7, and 14 to examine the plasma biochemical parameters and proinflammatory cytokines. The RPG supplementation increased the milk yield, but did not change the dry matter intake. Compared with cows in the CON group, the plasma total protein concentration was lower in the RPG group. Cows in the RPG group had greater plasma albumin concentrations but lower globulin and interleukin-8 concentrations during the transition period. The RPG supplementation tended to increase the plasma alanine aminotransferase concentration but did not change the plasma aspartate aminotransferase concentration. Dietary RPG supplementation increased the non-esterified fatty acid concentration and tended to decrease the plasma glucose concentration. In conclusion, these results indicate that supplementation with 200 g RPG per day improves milk production and reduces inflammatory markers but might have compromised the liver function of the transition cows in this study.

Physiologic Responses to Feeding Rumen-Protected Glucose to Lactating Dairy Cows

It was hypothesized that rumen-protected glucose (RPG) in diets of dairy cows increases concentrations of insulin resulting in greater blood progesterone concentrations because elevated insulin decreases activity of liver enzymes inactivating steroid hormones. Timing of ovulation was synchronized among 64 postpartum Holstein cows using GnRH and PGF2α (Day 0 = ovulation). Cows were milked thrice daily and assigned randomly a basal diet supplemented with 0, 1, 2, or 4 kg of an RPG product in place of corn grain, top-dressed in the diet beginning on Day -3. Blood was collected pre- and post-prandial on Days 0, 2, and 4 to determine plasma glucose and insulin concentrations and daily from Days 2 through 12. Intake of crude protein and energy-soluble carbohydrates increased linearly with dose, whereas starch intake decreased linearly with dose. Neither daily milk yield nor dry matter intake (DMI), energy-corrected milk (ECM), somatic cell count, or percentages of milk fat, protein and lactose on Day 8 differed among dietary treatments. Neither pre- nor post-prandial changes in plasma glucose differed among treatments. In contrast, post-prandial glucose decreased from Days 0 through 4. A change in plasma insulin (post-prandial minus pre-prandial) was detected. Milk urea nitrogen increased linearly with RPG dose. Concentrations of progesterone were unaffected by RPG dose. It is concluded that insulin response to RPG was decreased relative to the control and RPG supplementation linearly increased crude protein intake and milk urea nitrogen with increasing dose, but did not affect concentrations of progesterone, milk yield, or dry matter intake.