The effect of dietary pioglitazone supplementation on milk yield, insulin sensitivity and GH-IGF-I axis in Holstein dairy cows during the transition period

BACKGROUND

High-yielding dairy cows develop insulin resistance during late gestation associated with disruption of the growth hormone (GH)-insulin-like growth factor (IGF)-I axis and cause metabolic and reproductive disorders.

OBJECTIVE

This study aimed to determine the effects of dietary pioglitazone (PIO) supplementation as an insulin sensitizer agent on milk yield, plasma metabolite status and GH-IGF-I axis in transition Holstein dairy cows.

METHODS

Twenty multiparous cows were randomly assigned into two experimental groups (n = 10 animals per group) and either fed with a basal diet (control) or the basal diet supplemented with 6 mg PIO/kg body weight (BW) from day 14 before parturition to day 21 postpartum. The BW and body condition score (BCS), non-esterified fatty acids, beta-hydroxybutyrate (BHBA), insulin, glucose, GH and IGF-I concentrations, milk production and composition were measured weekly.

RESULTS

BW and BCS losses were lower in PIO than in control cows (p < 0.05). The percentage and amount of milk fat were decreased, and the amount of protein increased only in the first post-calving week in the PIO-treated cows compared to the control (p < 0.05). Dietary PIO supplementation increased glucose concentration at calving, but insulin concentration was increased at calving and in the first post-calving week (p < 0.05). Plasma concentrations of IGF-I and the ratio of IGF to GH were increased in the PIO group (p < 0.05). The mean revised quantitative insulin sensitivity check index with BHBA, as an insulin sensitivity index, was greater in PIO-supplemented cows (p < 0.05).

CONCLUSIONS

Our results showed beneficial effects of PIO supplementation on improving insulin sensitivity and the GH-IGF-I axis that may cause lower negative energy balance and better metabolic and health status in transition dairy cows.

Blood neutrophil extracellular traps: a novel target for the assessment of mammary health in transition dairy cows

Background

Mammary health is important for transition dairy cows and has been well recognized to exert decisive effects on animal welfare. However, the factors influencing mammary health are still unclear. Differential somatic cell count (DSCC) could reflect the mastitis risk since it is the percentage of neutrophils plus lymphocytes in total somatic cells and could be reflective of mammary health of dairy cows. This work aimed to investigate the assessment and prognosis of the health of transition cows based on blood neutrophil extracellular traps (NETs).

Results

Eighty-four transition Holstein dairy cows were selected. The serum was sampled in all the animals at week 1 pre- and postpartum, and milk was sampled at week 1 postpartum. Based on the DSCC in milk at week 1, cows with lower (7.4% ± 4.07%, n = 15) and higher (83.3% ± 1.21%, n = 15) DSCCs were selected. High DSCC cows had higher levels of red blood cell counts (P < 0.05), hemoglobin (P = 0.07), and hematocrit (P = 0.05), higher concentrations of serum oxidative variables [(reactive oxygen species (P < 0.05), malondialdehyde (P < 0.05), protein carbonyl (P < 0.05), and 8-hydroxy-2-deoxyguanosine (P = 0.07)], higher levels of serum and milk NETs (P < 0.05) and blood-milk barrier indicators, including serum β-casein (P = 0.05) and milk immunoglobulin G2 (P = 0.09), than those of low DSCC cows. In addition, lower concentrations of serum nutrient metabolites (cholesterol and albumin) (P < 0.05) and a lower level of serum deoxyribonuclease I (P = 0.09) were observed in high DSCC cows than in low DSCC cows. Among the assessments performed using levels of the three prepartum serum parameters (NETs, deoxyribonuclease I and β-casein), the area under the curve (0.973) of NETs was the highest. In addition, the sensitivity (1.00) and specificity (0.93) were observed for the discrimination of these cows using NETs levels with a critical value of 32.2 ng/mL (P < 0.05).

Conclusions

The formation of NETs in blood in transition dairy cows may damage the integrity of the blood-milk barrier and thereby increase the risk for mastitis in postpartum cows.

Dynamic ROS Production and Gene Expression of Heifers Blood Neutrophil in a Oligofructose Overload Model

Alimentary oligofructose (OF) overload can induce several diseases in cattle, such as ruminal acidosis, laminitis, and synovitis. The role of blood polymorphonuclear neutrophil (PMN) remains unclear during OF overload. The aim of this study was to investigate the dynamic changes in reactive oxygen species (ROS) production and the expression profile of genes in blood PMN in a model of OF overload. Twelve clinically healthy and non-pregnant Chinese Holstein heifers, aged between 18 and 26 mo, weighing 335–403 kg, BCS (5-point scale) ranges 2.7–3.3 were used for the experiments. OF heifers (n = 6) received 17 g/kg of BW oligofructose dissolved in 2 L/100 kg of BW tap water and the CON heifers (n = 6) received 2 L/100 kg of BW tap water. Blood PMN was isolated for each heifer 0, 6, 12, 18, 24, 36, 48, 60, and 72 h after administration. PMN was analyzed either by endogenous and phorbol myristate acetate (PMA)-induced ROS production or by quantitative real-time PCR. After 12 h, PMA-induced ROS production decreased, which was sustained until 48 h. The expressions of inflammation markers (IL1α, IL1β, IL6, IL10, TNFα, STAT3, TLR4, MMP9, and HP) and eicosanoids (ALOX5, ALOX5AP, and PLA2G4A) were upregulated. The expression of adhesion and migration (CXCR2, CXCL8, CD62L, ITGA4, ITGAM, and ITGB2) in OF heifers was increased compared with CON heifers. The expression of oxidative stress (SOD2 and S100A8) was upregulated, while SOD1 and MPO were downregulated. In metabolism and receptor genes, the expressions of GRα and INSR decreased after 12 h, while Fas increased until 6 h and then decreased at 18 h. The expression of LDHA and PANX1 did not show any differences after OF overload. These findings indicate that OF overload induced systemic activation of PMN, which provides a step toward a better understanding of the role of innate immune responses in response to oral OF administration.

Peripheral leukocyte and endometrium molecular biomarkers of inflammation and oxidative stress are altered in peripartal dairy cows supplemented with Zn, Mn, and Cu from amino acid complexes and Co from Co glucoheptonate

Background

Immune dysfunction and a higher risk of uterine infections are characteristics of the transition into lactation in dairy cows. The supply of complexed trace minerals, which are more bioavailable, could help overcome the greater needs of these nutrients in tissues around parturition and early lactation.

Results

Twenty Holstein cows received an oral bolus with a mix of inorganic trace minerals (INO) or complexed trace minerals (AAC) to achieve 75, 65, 11, and 1 ppm supplemental Zn, Mn, Cu, and Co, respectively, in the total diet dry matter from -30 d through +30 d relative to parturition. Blood for polymorphonuclear leukocyte (PMNL) isolation was collected at -30, -15, +10, and + 30 d relative to parturition, whereas endometrium biopsies were performed at +14 and +30 d. Feeding AAC led to greater PMNL expression of genes related with inflammation response (DDX58), oxidative stress response (MPO), eicosanoid metabolism (PLA2G4A and ALOX5AP), transcription regulation (PPARG), and cellular adhesion (TLN1). The upregulation by AAC in endometrium of genes related with inflammation response (TLR2, TLR4, NFKB1, TNF, IL6, IL1B, IL10, IL8), prostaglandin synthesis (PTGS2, PTGES), and antioxidant responses (NFE2L2, SOD1) indicated a faster remodeling of uterine tissue and potentially greater capacity to control a local bacterial invasion.

Conclusions

Data indicate that trace mineral supplementation from amino acid complexes improves PMNL activity and allows the prompt recovery of uterine tissue during early lactation. As such, the benefits of complexed trace minerals extend beyond an improvement of liver function and productive performance.

Electronic supplementary material

The online version of this article (doi:10.1186/s40104-017-0163-7) contains supplementary material, which is available to authorized users.

Impact of metritis on the generation of reactive oxygen species by circulating phagocytes and plasma lipopolysaccharide concentration in peripartum dairy cows

This study examined the relationship between postpartum metritis, reactive oxygen species (ROS) generation, and plasma lipopolysaccharide (LPS) concentration in peripartum dairy cows. Blood was collected twice weekly from 2 weeks prepartum through 6 weeks postpartum. Whole blood chemiluminescence (WBCL) was measured using the luminol-enhanced zymosan-stimulated chemiluminescence assay. Cows were examined for uterine health disorders and classified into two groups, healthy (n = 11) and metritis (n = 5). Metritis had a significant effect on WBCL, with cows with metritis having a higher WBCL. Plasma LPS concentrations in cows with metritis were significantly higher than in healthy cows. To examine the effect of LPS on WBCL, blood was sampled in healthy peripartum cows (1 to 2 weeks prepartum, n = 8; 0 to 3 weeks postpartum, n = 11; and 4 to 8 weeks postpartum, n = 8) and incubated with LPS. At 1 endotoxin units/mL of LPS, similar to the plasma LPS concentration in cows with metritis, the WBCL increased in cows at 0 to 3 weeks postpartum. Results indicate that the increase in ROS generation and plasma LPS concentration are associated with metritis, and LPS may be responsible for enhanced ROS generation in early postpartum dairy cows.

Effects of whole flaxseed, raw soybeans, and calcium salts of fatty acids on measures of cellular immune function of transition dairy cows

The objective of the current study was to evaluate the effects of supplemental n-3 and n-6 fatty acid (FA) sources on cellular immune function of transition dairy cows. Animals were randomly assigned to receive 1 of 4 diets: control (n=11); whole flaxseed (n-3 FA source; n=11), 60 and 80g/kg of whole flaxseed [diet dry matter (DM) basis] during pre- and postpartum, respectively; whole raw soybeans (n-6 FA source; n=10), 120 and 160g/kg of whole raw soybeans (diet DM basis) during pre- and postpartum, respectively; and calcium salts of unsaturated FA (Megalac-E, n-6 FA source; n=10), 24 and 32g/kg of calcium salts of unsaturated FA (diet DM basis) during pre- and postpartum, respectively. Supplemental FA did not alter DM intake and milk yield but increased energy balance during the postpartum period. Diets containing n-3 and n-6 FA sources increased phagocytosis capacity of leukocytes and monocytes and phagocytosis activity of monocytes. Furthermore, n-3 FA source increased phagocytic capacity of leukocytes and neutrophils and increased phagocytic activity in monocytes and neutrophils when compared with n-6 FA sources. Supplemental FA effects on adaptive immune system included increased percentage of T-helper cells, T-cytotoxic cells, cells that expressed IL-2 receptors, and CD62 adhesion molecules. The results of this study suggest that unsaturated FA can modulate innate and adaptive cellular immunity and trigger a proinflammatory response. The n-3 FA seems to have a greater effect on phagocytic capacity and activity of leukocytes when compared with n-6 FA.

Postpartal immunometabolic gene network expression and function in blood neutrophils are altered in response to prepartal energy intake and postpartal intramammary inflammatory challenge

The effect of over-feeding energy prepartum on blood polymorphonuclear neutrophil (PMN) response remains unclear. Cows fed controlled (CON; 1.34Mcal/kg of dry matter) or excess energy (OVE; 1.62Mcal/kg dry matter) during the dry period (~45d before expected calving date) received an intramammary (IM) challenge with Escherichia coli lipopolysaccharide (LPS) during the postpartal period to determine the effects of IM LPS and prepartal diet on the expression of key genes associated with immunometabolic response in blood PMN. Feed intake and daily milk yield were recorded throughout the study period. At 7d in milk (DIM), all cows received LPS (200µg) into 1 rear mammary quarter. Blood PMN were isolated at 7, 14, and 30 DIM, as well as before (0h) and after (12h) IM LPS challenge for gene expression analysis using quantitative real time PCR. Phagocytosis capabilities in vitro were assessed at 7, 14, and 30 DIM. Data were analyzed using the MIXED procedure of SAS with repeated measures. No differences in feed intake and milk yield were observed between OVE- and CON-fed cows. As expected, IM LPS challenge altered the expression of genes associated with the immune response (e.g., 1.9- and 1.8-fold for SELL and TLR2, respectively), metabolism (e.g., 1.8- and -1.8-fold for LDHA and SLC2A1, respectively), and transcription (e.g., 1.1- and 1.7-fold for NCOR1 and PPARD, respectively). At 12h postchallenge, an upregulation of TLR2 (1.8-fold), HIF1A (1.9-fold), and NFKB1 (1.5-fold) was observed for OVE rather than CON. At 7 DIM, S100A9 tended (2.2-fold) to be upregulated for OVE rather than CON. At 14 DIM, OVE resulted in lower PMN phagocytosis and an upregulation of NCOR2 (1.6-fold) and RXRA (1.9-fold) compared with CON-fed cows. At 30 DIM, an upregulation of MPO (3.5-fold) and PLA2G4A (1.5-fold) and a tendency for RXRA (1.7-fold) was observed for OVE- rather than CON-fed cows. Our results suggest that IM LPS challenge altered gene expression associated with metabolism in PMN and that OVE impaired PMN phagocytosis and increased the expression of immunometabolic genes after IM LPS challenge and during the postpartal period. The current study provides new linkages among prepartal feed energy intake, metabolism, and immune response of blood PMN and risk of disease during early lactation.

Practical applications of trace minerals for dairy cattle

Trace minerals have critical roles in the key interrelated systems of immune function, oxidative metabolism, and energy metabolism in ruminants. To date, the primary trace elements of interest in diets for dairy cattle have included Zn, Cu, Mn, and Se although data also support potentially important roles of Cr, Co, and Fe in diets. Trace minerals such as Zn, Cu, Mn, and Se are essential with classically defined roles as components of key antioxidant enzymes and proteins. Available evidence indicates that these trace minerals can modulate aspects of oxidative metabolism and immune function in dairy cattle, particularly during the transition period and early lactation. Chromium has been shown to influence both immune function and energy metabolism of cattle; dairy cows fed Cr during the transition period and early lactation have evidence of improved immune function, increased milk production, and decreased cytological endometritis. Factors that complicate trace mineral nutrition at the farm level include the existence of a large number of antagonisms affecting bioavailability of individual trace minerals and uncertainty in terms of requirements under all physiological and management conditions; therefore, determining the optimum level and source of trace minerals under each specific situation continues to be a challenge. Typical factorial approaches to determine requirements for dairy cattle do not account for nuances in biological function observed with supplementation with various forms and amounts of trace minerals. Trace mineral nutrition modulates production, health, and reproduction in cattle although both formal meta-analysis and informal survey of the literature reveal substantial heterogeneity of response in these outcome variables. The industry has largely moved away from oxide-based programs toward sulfate-based programs; however, some evidence favors shifting supplementation strategies further toward more bioavailable forms of inorganic and organic trace minerals. Furthermore, opportunities for specific modulation of aspects of health, milk production, and reproduction through supplementation strategies for diets of transition dairy cows are attractive because of the known dynamics of energy metabolism, immune function, and oxidative metabolism during this timeframe.

Functional Role of PPARs in Ruminants: Potential Targets for Fine-Tuning Metabolism during Growth and Lactation

Characterization and biological roles of the peroxisome proliferator-activated receptor (PPAR) isotypes are well known in monogastrics, but not in ruminants. However, a wealth of information has accumulated in little more than a decade on ruminant PPARs including isotype tissue distribution, response to synthetic and natural agonists, gene targets, and factors affecting their expression. Functional characterization demonstrated that, as in monogastrics, the PPAR isotypes control expression of genes involved in lipid metabolism, anti-inflammatory response, development, and growth. Contrary to mouse, however, the PPARγ gene network appears to controls milk fat synthesis in lactating ruminants. As in monogastrics, PPAR isotypes in ruminants are activated by long-chain fatty acids, therefore, making them ideal candidates for fine-tuning metabolism in this species via nutrients. In this regard, using information accumulated in ruminants and monogastrics, we propose a model of PPAR isotype-driven biological functions encompassing key tissues during the peripartal period in dairy cattle.

In vitro effects of Escherichia coli lipopolysaccharide on the function and gene expression of neutrophils isolated from the blood of dairy cows

The objectives of this study were to investigate the effect of Escherichia coli lipopolysaccharide (LPS) on the function of bovine neutrophils (PMNL) collected from mid lactation cows and determine the differential effects of LPS on gene expression of PMNL purified from early and mid lactation cows. The PMNL from mid lactation cows (187±13 d postpartum) were incubated with 0, 1, 25, and 50 μg/mL of LPS for 120 min, and the generation of reactive oxygen species (ROS), PMNL extracellular traps (NET), chemotaxis, and killing of Staphylococcus aureus were determined. Incubation of PMNL with 25 μg/mL of LPS increased intracellular ROS by 79% in mitogen-stimulated PMNL. Addition of 50 μg/mL of LPS enhanced intracellular ROS by nonstimulated and stimulated PMNL by 184 and 154%, respectively. Nonstimulated PMNL incubated with 25 and 50 μg/mL of LPS had a 105% increase in NET. Addition of LPS had no effect on subsequent PMNL chemotaxis or killing of Staph. aureus. To examine the effect of LPS on the expression of genes involved in PMNL function and cytokine production, mRNA was purified from PMNL isolated from mid lactation (146±2 postpartum; n=10) and early lactation cows (7 d postpartum; n=10), after a 120-min incubation with 0 or 50 μg/mL of LPS. Amounts of interleukin-8 (IL-8), tumor necrosis factor (TNF), bactericidal/permeability-increasing protein (BPI), myeloperoxidase (MPO), superoxide dismutase 2 (SOD2), NADPH oxidase 4 (NOX4), Cytochrome b-245, α polypeptide (CYBA), histone H2A/1 (H2A/1), and histone H2B-like (H2B) mRNA were determined relative to that of β-actin by real-time quantitative PCR. Regardless of stage of lactation, PMNL incubated with 50 μg/mL of LPS had 537 and 45% higher mRNA contents of IL-8 and SOD2 compared with 0 μg/mL LPS, respectively. In addition, LPS augmented the expression of TNF, BPI, and CYBA (2,908, 59, and 158% compared with controls, respectively) only in PMNL from mid lactation cows. Addition of LPS did not affect mRNA levels of MPO, NOX4, H2A/1, or H2B. Independent of LPS treatment, PMNL from mid lactation cows had 99% higher mRNA contents of IL-8 compared with PMNL from early lactation cows. The PMNL from early lactation cows had a 634% increase in MPO mRNA expression relative to that from mid lactation cows. These results support that LPS directly stimulates PMNL to produce ROS and express NET. In addition, LPS enhances the generation of ROS by PMNL in response to other stimuli and increases the expression of genes encoding inflammatory mediators and enzymes involved in the production of ROS. Finally, reduced PMNL gene expression of IL-8 (regardless of LPS activation), TNF, CYBA, and BPI (upon stimulation with LPS) in early lactation may elucidate several mechanisms by which PMNL may become immune-incompetent during this period.

Effects of prepartum 2,4-thiazolidinedione on insulin sensitivity, plasma concentrations of tumor necrosis factor-α and leptin, and adipose tissue gene expression

Administration of peroxisome proliferator-activated receptor gamma (PPARγ) ligands, thiazolidinediones (TZD), to prepartum dairy cattle has been shown to improve dry matter intake and decrease circulating nonesterified fatty acids (NEFA) around the time of calving. The objective of this work was to elucidate mechanisms of TZD action in transition dairy cattle by investigating changes in plasma leptin, tumor necrosis factor-α (TNFα), the revised quantitative insulin sensitivity check index (RQUICKI), and adipose tissue gene expression of leptin, PPARγ, lipoprotein lipase (LPL), and fatty acid synthase (FAS). Multiparous Holstein cows (n=40) were administered 0, 2.0, or 4.0 mg of TZD/kg of body weight (BW) by intrajugular infusion once daily from 21 d before expected parturition until parturition. Plasma samples collected daily from 22 d before expected parturition through 21 d postpartum were analyzed for glucose, NEFA, and insulin. Plasma samples collected on d -14, -3, -1, 1, 3, 7, 14, and 49 relative to parturition were also analyzed for leptin and TNFα. Adipose tissue was collected on d 7 before expected parturition from a subset of cows, and gene expression was examined via quantitative real-time PCR. A tendency for a treatment by time effect on plasma leptin prepartum was observed such that values were similar on d -14 but cows receiving 2.0 mg/kg of BW of TZD tended to have lower circulating leptin as calving approached. Postpartum leptin tended to be increased linearly (2.3, 2.4, and 2.5±0.1 ng/mL for 0, 2.0, and 4.0 mg/kg treatments, respectively) in cows that received TZD prepartum. Plasma TNFα increased linearly (2.6, 3.7, and 4.0±0.1 pg/mL) in response to TZD treatment and decreased through the first week postpartum. Calculation of RQUICKI 1/[log(glucose)+log(insulin)+log(NEFA)] suggested altered insulin sensitivity in cows administered TZD that may depend on day relative to calving. Administration of TZD increased adipose tissue expression of PPARγ mRNA (11.0, 13.3, and 12.8±1.9). Administration of TZD had a quadratic effect on gene expression of leptin (16.2, 10.7, and 17.4±1.6) and no effect on LPL expression, and expression of FAS was lower for TZD-treated cows than for controls (8.2, 4.2, and 6.1±1.8, respectively). Results imply altered expression and plasma concentrations of leptin, increased plasma TNFα concentrations, and increased expression of PPARγ in adipose tissue as potential mechanisms for the effects of TZD administration on transition dairy cattle.