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Previous research demonstrated that nutrition during the far-off (early) dry period may be as important to transition success as nutrition during the close-up dry period. Our objectives were to determine if a low-energy, high-fiber diet fed throughout the dry period improved metabolic status and production of dairy cows compared with a higher-energy diet or a 2-diet system, and to compare responses of cows and heifers to those diets. Holstein cows (n = 25 with 10 primiparous per treatment) were assigned to each of 3 diets at 60 d before expected calving. Treatment LO [40.5% wheat straw; 5.6 MJ of net energy for lactation (NEL)/kg of DM] was designed to meet but not exceed National Research Council recommendations for ad libitum intake from dry-off until calving. Treatment HI was a high-energy diet (6.7 MJ of NEL/kg of DM) fed for ad libitum intake from dry-off until calving. For the LO+HI treatment, the LO diet was fed ad libitum from dry-off until 21 d before expected calving, followed by the HI diet until parturition. After parturition all cows were fed a lactation diet (7.0 MJ of NEL/kg of DM) through 63 d postpartum. Dry matter intake and body weight were greater for HI cows prepartum, but not postpartum. When LO+HI cows were switched to the HI diet, their dry matter intake increased to match that of HI cows. Cows fed HI had greater gain of body condition before calving but lost more postpartum. Energy balance postpartum was higher for LO cows than for HI cows. Milk production, protein content, and protein yield did not differ among diets. Milk fat content and yield were highest for HI cows, lowest for LO, and intermediate for LO+HI cows. The HI cows had lower serum nonesterified fatty acids prepartum than either LO or LO+HI, but greater concentrations postpartum. Serum β-hydroxybutyrate did not differ prepartum, but was greater for HI than for LO or LO+HI postpartum. Serum glucose and insulin were lower for LO than HI and LO+HI prepartum; insulin was lower for LO and HI than for LO+HI postpartum. The LO cows had lower liver total lipid concentration postpartum than the HI cows and LO+HI cows. Primiparous cows generally responded to diets the same as multiparous cows. The LO+HI feeding strategy provided no benefit over the LO diet. Moreover, the high-energy diet, even when fed for only 19 d before calving in the LO+HI group, resulted in increased serum β-hydroxybutyrate and liver total lipid concentrations compared with LO.

In early lactation, susceptibility to disease is greatest, impacting cow health and productivity and leading to economic losses. Mastitis is the most economically costly disease to the dairy industry and is most frequent at this time. The objective of this paper is to discuss the energetic fuels used by leukocytes in the metabolic response during mastitis that may reveal potential mechanisms linking mastitis with the development of subsequent metabolic diseases for dairy cows during lactation. Glucose and glutamine are the primary fuels used by leukocytes and are essential substrates for optimal leukocyte function. Yet because these substrates are in high demand to support milk synthesis during early lactation, their supply to leukocytes may be compromised and may partly contribute to immunosuppression observed at this time. Production-related metabolic diseases during early lactation, such as ketosis and hepatic lipidosis, can also adversely affect health and productivity. Risk of subsequent disease for cows during mastitis has not been fully elucidated. Regardless of stage of lactation and physiological state, increases in circulating NEFA and glucose and decreases in ketones during an intramammary inflammation in dairy cows have been reported. In addition, previous work indicates that hepatic metabolism may be impaired during inflammation. These results indicate a potential link between mastitis and the risk of subsequent metabolic disease for dairy cows during lactation. This paper will discuss the complex relationships between metabolism and immune function and how these immunometabolic interactions relate mastitis with increased risk of subsequent disease during early lactation.

In Table 3 (page 6478), the means and standard errors of the difference (SED) for 9 of the parameters were tabulated as log values, rather than in the original units. All P-values and Tukey comparisons are correct. The corrected table is shown below, with corrected parameters and values in bold. The authors regret the errors.

Cows experience some degree of negative energy balance and immunosuppression around parturition, making them vulnerable to metabolic and infectious diseases. The effect of prepartum feeding of diets to meet (control, 1.34 Mcal/kg of dry matter) or exceed (overfed, 1.62 Mcal/kg of dry matter) dietary energy requirements was evaluated during the entire dry period (∼45 d) on blood polymorphonuclear neutrophil function, blood metabolic and inflammatory indices, and milk production in Holstein cows. By design, dry matter intake in the overfed group (n=9) exceeded energy requirements during the prepartum period (-4 to -1 wk relative to parturition), resulting in greater energy balance when compared with the control group (n=10). Overfed cows were in more negative energy balance during wk 1 after calving than controls. No differences were observed in dry matter intake, milk yield, and milk composition between diets. Although nonesterified fatty acid concentration pre- (0.138 mEq/L) and postpartum (0.421 mEq/L) was not different between diets, blood insulin concentration was greater in overfed cows prepartum (16.7 μIU/mL) compared with controls pre- and postpartum (∼3.25 μIU/mL). Among metabolic indicators, concentrations of urea (4.63 vs. 6.38 mmol/L), creatinine (100 vs. 118 μmol/L), and triacylglycerol (4.0 vs. 8.57 mg/dL) in overfed cows were lower prepartum than controls. Glucose was greater pre- (4.24 vs. 4.00 mmol/L) and postpartum (3.49 vs. 3.30 mmol/L) compared with control cows. Among liver function indicators, the concentration of bilirubin increased by 2 to 6 fold postpartum in control and overfed cows. Phagocytosis capacity of polymorphonuclear neutrophils was lower prepartum in overfed cows (32.7% vs. 46.5%); phagocytosis in the control group remained constant postpartum (50%) but it increased at d 7 in the overfed group to levels similar to controls (48.4%). Regardless of prepartum diet, parturition was characterized by an increase in nonesterified fatty acid and liver triacylglycerol, as well as blood indices of inflammation (ceruloplasmin and haptoglobin), oxidative stress (reactive oxygen metabolites), and liver injury (glutamic oxaloacetic transaminase). Concentrations of the antioxidant and anti-inflammatory compounds vitamin A, vitamin E, and β-carotene decreased after calving. For vitamin A, the decrease was observed in overfed cows (47.3 vs. 27.5 μg/100 mL). Overall, overfeeding energy and higher energy status prepartum led to the surge of insulin and had a transient effect on metabolism postpartum.

Cows experiencing severe postpartal negative energy balance (NEB) are at greater risk of developing mastitis than cows in positive energy balance (PEB). Our objectives were to compare mammary tissue gene expression profiles between lactating cows (n = 5/treatment) subjected to feed restriction to induce NEB and cows fed ad libitum to maintain PEB in order to identify genes involved in immune response and cellular metabolism that may predispose cows to an intramammary infection in non-infected mammary gland. The NEB cows were feed-restricted to 60% of calculated net energy for lactation requirements, and cows fed PEB cows were fed the same diet ad libitum. At 5 days after feed restriction, one rear mammary gland from all cows was biopsied for RNA extraction and transcript profiling using microarray and quantitative PCR. Energy balance (NEB vs. PEB) resulted in 278 differentially expressed genes (DEG). Among up-regulated DEG (n = 180), Ingenuity Pathway Analysis® identified lipid metabolism (8) and molecular transport (14) as some of the most enriched molecular functions. Genes down-regulated by NEB (98) were associated with cell growth and proliferation (21) and cell death (18). Results indicate that DEG due to NEB in mid-lactation were associated with numerous biological functions but we did not identify genes that could, a priori, be associated with risk of intramammary infection in non-infected mammary glands. Further studies with early postpartal cows are required Cows experiencing severe postpartal negative energy balance (NEB) are at greater risk of developing mastitis than cows in positive energy balance (PEB). Our objectives were to compare mammary tissue gene expression profiles between lactating cows (n = 5/treatment) subjected to feed restriction to induce NEB and cows fed ad libitum to maintain PEB in order to identify genes involved in immune response and cellular metabolism that may predispose cows to an intramammary infection in non-infected mammary gland. The NEB cows were feed-restricted to 60% of calculated net energy for lactation requirements, and cows fed PEB cows were fed the same diet ad libitum. At 5 days after feed restriction, one rear mammary gland from all cows was biopsied for RNA extraction and transcript profiling using microarray and quantitative PCR. Energy balance (NEB vs. PEB) resulted in 278 differentially expressed genes (DEG). Among up-regulated DEG (n = 180), Ingenuity Pathway Analysis® identified lipid metabolism (8) and molecular transport (14) as some of the most enriched molecular functions. Genes down-regulated by NEB (98) were associated with cell growth and proliferation (21) and cell death (18). Results indicate that DEG due to NEB in mid-lactation were associated with numerous biological functions but we did not identify genes that could, a priori, be associated with risk of intramammary infection in non-infected mammary glands. Further studies with early postpartal cows are required

Udgivelsesdato: April Our objective was to compare mammary tissue gene expression profiles during a Streptococcus uberis (S. uberis) mastitis challenge between lactating cows subjected to dietary-induced negative energy balance (NEB; n = 5) and cows fed ad libitum to maintain positive energy balance (PEB; n = 5) in order to better understand the mechanisms associated with NEB and risk of mastitis during the transition period. The NEB cows were feed-restricted to 60% of calculated net energy for lactation requirements for 7 d, and cows assigned to PEB were fed the same diet for ad libitum intake. Five days after feed restriction, one rear mammary quarter of each cow was inoculated with 5,000 cfu of S. uberis (O140J). At 20 h post-inoculation, S. uberis-infected mammary quarters from all cows were biopsied for RNA extraction. Energy balance (NEB vs. PEB) resulted in 287 differentially expressed genes (DEG; FDR 0.05), with 86 DEG up-regulated and 201 DEG down-regulated. Canonical pathways most affected by NEB were IL-8 Signaling (10 genes), Glucocorticoid Receptor Signaling (13), and NRF2-mediated Oxidative Stress Response (10). Among genes differentially expressed by NEB, Cell Growth and Proliferation (48) and Cellular Development (36) were the most enriched functions. Regarding immune response, HLA-A was up-regulated due to NEB, whereas the majority of genes involved in immune response were down-regulated (e.g., AKT1, IRAK1, MAPK9, and TRAF6). This study provided new avenues for investigation into the mechanisms relating NEB and susceptibility to mastitis in lactating dairy cows.

Udgivelsesdato: March 2010 Our objectives were to compare gene expression profiles in blood polymorphonuclear cells (PMN) during a Streptococcus uberis intramammary challenge between lactating cows subjected to feed restriction to induce negative energy balance (NEB; n = 5) and cows fed ad libitum to maintain positive energy balance (PEB; n = 5). After 5 days of feed restriction, one rear mammary quarter of each cow was inoculated with 5,000 cfu of S. uberis. Blood PMN were isolated at 24 h post-inoculation from all cows for mRNA expression via quantitative polymerase chain reaction for 20 genes associated with immune response and metabolism. A total of 12 genes were differentially expressed in blood PMN in NEB versus PEB cows. Upregulated genes by NEB were ALOX5AP, CPNE3, IL1R2, IL6, TLR2, TLR4, and THY1, and downregulated genes were HLA-DRA, HLA-A, IRAK1, SOD1, and TNF. Network analysis revealed that TNF was associated with several of the affected genes in NEB cows compared with PEB cows. Results showed that 24 h after intramammary challenge with S. uberis, cows in NEB had altered PMN expression of genes involved with immune response. Our data provide new information on transcriptomic mechanisms associated with NEB and the corresponding inhibition of immune response in lactating dairy cows.

BackgroundInformation generated via microarrays might uncover interactions between the mammary gland andStreptococcus uberis(S. uberis) that could help identify control measures for the prevention and spread ofS. uberismastitis, as well as improve overall animal health and welfare, and decrease economic losses to dairy farmers. The main objective of this study was to determine the most affected gene networks and pathways in mammary tissue in response to an intramammary infection (IMI) withS. uberisand relate these with other physiological measurements associated with immune and/or metabolic responses to mastitis challenge withS. uberisO140J.ResultsStreptococcus uberisIMI resulted in 2,102 (1,939 annotated) differentially expressed genes (DEG). Within this set of DEG, we uncovered 20 significantly enriched canonical pathways (with 20 to 61 genes each), the majority of which were signaling pathways. Among the most inhibited wereLXR/RXR SignalingandPPARα/RXRα Signaling. Pathways activated by IMI wereIL-10 SignalingandIL-6 Signalingwhich likely reflected counter mechanisms of mammary tissue to respond to infection. Of the 2,102 DEG, 1,082 were up-regulated during IMI and were primarily involved with the immune response, e.g.,IL6,TNF,IL8, IL10, SELL, LYZ, andSAA3. Genes down-regulated (1,020) included those associated with milk fat synthesis, e.g.,LPIN1, LPL, CD36, andBTN1A1. Network analysis of DEG indicated thatTNFhad positive relationships with genes involved with immune system function (e.g.,CD14, IL8, IL1B, andTLR2) and negative relationships with genes involved with lipid metabolism (e.g.,GPAM,SCD,FABP4,CD36, andLPL) and antioxidant activity (SOD1).ConclusionResults provided novel information into the early signaling and metabolic pathways in mammary tissue that are associated with the innate immune response toS. uberisinfection. Our study indicated that IMI challenge withS. uberis(strain O140J) elicited a strong transcriptomic response, leading to potent activation of pro-inflammatory pathways that were associated with a marked inhibition of lipid synthesis, stress-activated kinase signaling cascades, and PPAR signaling (most likely PPARγ). This latter effect may provide a mechanistic explanation for the inverse relationship between immune response and milk fat synthesis.

Our objective was to identify specific blood markers as risk factors for the development of mastitis during early lactation. We used a subset of cows from a larger experiment that consisted of a total of 634 lactations from 317 cows. Cows were of 3 breeds and ranged from parity 1 to 4. Blood samples were collected weekly from 56 d before expected calving date through 90 d in milk (DIM). Blood was analyzed for several hormones, metabolites, and enzymes, and energy intake and energy balance were calculated. Veterinary treatment records and daily composite milk somatic cell counts were analyzed and used to determine incidence and severity of mastitis in early lactation. Cows were separated into 2 groups: 1) WK0, consisting of cows that developed clinical mastitis (CM), cows that developed subclinical mastitis (SM), or cows that were healthy (H) during the first 7 DIM; and 2) EL, consisting of CM, SM, or H cows during wk 2 through 13 of lactation. Data were adjusted for numerous fixed effects (e.g., parity, breed, season, and DIM) before statistical analysis. The time of mastitis (TOM) was recorded as the DIM in which the first rise in somatic cell count was observed and was recorded as TOM = 0. The time before and after TOM was distinguished as ± n wk relative to TOM = 0. Healthy cows were paired with either a SM or CM cow and the TOM for each H cow was equal to the TOM for its paired SM or CM cow. Data from wk -1 and -2 relative to TOM were analyzed for group WK0 and EL, respectively. For all parameters, SM cows did not differ from H cows from either group. The CM cows had higher nonesterified fatty acid levels and a tendency toward higher β-hydroxybutyrate levels than H cows before mastitis for both groups. For group WK0, glucose was higher -1 wk relative to calving in CM than H cows. For group EL, aspartate aminotransferase was higher -2 wk relative to mastitis in CM than H cows during 8 to 90 DIM. All other variables were similar among CM, SM, and H cows for both groups. Our results indicate that substances in blood, especially nonesterified fatty acids and aspartate aminotransferase, may be potential markers for the risk of mastitis in early lactation.

Ten multiparous Holstein cows were used to determine the effects of negative energy balance (NEB) on the immune response to a Streptococcus uberis (strain O140J) mastitis challenge during midlactation. Before the study, milk from all quarters of each cow was bacteriologically negative, with a composite somatic cell count of

Heifers ( n = 136) from 5 herds were treated with a commercially available β-lactam intramammary (IMM) antibiotic preparation containing cephapirin sodium at 10–21 d prior to anticipated parturition to evaluate the risk of antibiotic residues occurring in milk postpartum and to determine factors associated with antibiotic residues and IMM pathogen presence in milk postpartum. Mammary secretions collected from quarters before antibiotic administration and during weeks 1, 2 and 3 postpartum were analyzed for mastitis pathogens. Composite milk was collected at milkings 3, 6 and 10 postpartum and analyzed for β-lactam residues using a microbial inhibition antibiotic residue screening test. Antibiotic residues were confirmed with β-lactamase treatment and re-tested for residues. Residues were detected in 28.0, 8.82 and 3.68% of milk samples obtained at the third, sixth, and tenth milking postpartum, respectively. Increases in interval between prepartum antibiotic therapy and parturition and an increase in the postpartum interval to sampling were associated with a decrease in risk of antibiotic residues. The presence of antibiotic residues in milk at the third milking was associated with a reduced risk for IMM pathogen prevalence in the first 21 d postpartum. Lower somatic cell counts, an increase in mean milk yield over 200 days in milk and a reduction in IMM pathogen prevalence were associated with the presence of an antibiotic in milk postpartum. Screening milk for antibiotic residues in milk postpartum following prepartum antibiotic therapy in heifers is recommended to reduce the risk for antibiotic residue contamination of milk.

Preparturient heifers (n = 561) from 9 herds in 6 US states and 1 Canadian province were enrolled in a study to test the hypothesis that prepartum intramammary therapy would cure existing intramammary infections (IMI) and lead to increased milk production, reduced linear somatic cell count (LSCC), and improved reproductive performance. Mammary secretions were collected 10 to 21 d before expected calving from each quarter. Heifers were then assigned by identification number to receive intramammary therapy consisting of infusion of one tube per mammary quarter of a lactating cow commercial antibiotic preparation containing cephapirin or to a nontreated control group. Overall, 34.1% of mammary quarters were infected with a mastitis pathogen before parturition and 63.4% of heifers had at least one mammary quarter infected. The coagulase-negative staphylococci (CNS) caused the majority (74.8%) of prepartum IMI. Coagulase-positive staphylococci, environmental streptococci, and coliforms accounted for 24.5% of prepartum infections. Treatment had a significant effect on the cure rate of infected mammary quarters. Mammary quarters that were infected prepartum and treated with antibiotics had a 59.5% efficacy of cure rate and the percentage reduction in heifers with IMI was 51.9. Control quarters had a spontaneous cure rate of 31.7%. Treatment did not significantly affect milk production or LSCC in the first 200 d of lactation; however, there was a significant treatment by herd interaction for milk production. Quarters cured of either CNS or major pathogens had a lower LSCC in the first 200 d of lactation. No significant effect on services per conception or days open between treatment and control groups was observed. This trial demonstrated that prepartum intramammary antibiotic therapy did reduce the number of heifer IMI postpartum. Milk production, LSCC, and reproductive performance during the first 200 d of the first lactation were not significantly affected by treatment. Given these results, use of prepartum intramammary antibiotic therapy in heifers as a universal strategy to increase milk production in first-lactation dairy cows may not be warranted.