A randomized control trial to test the effect of pegbovigrastim treatment at dry-off on plasma and milk oxylipid profiles during early mammary gland involution and the postparturient period.

The early period of mammary gland involution is a critical juncture in the lactation cycle that can have significant effects on milk production and mammary gland health. Pegbovigrastim (PEG) administered 1 wk prior and on the day of parturition can enhance immune function and reduce the incidence of mastitis in the early postpartum period. Oxylipids are potent metabolites of polyunsaturated fatty acids (PUFA) and are important mediators of inflammation. The objective of this study was to evaluate effects of PEG given 1 wk before and at the day of dry-off (D0) on concentrations of oxylipids in plasma and milk from 7 d before D0 to 14 d after, as well as the effects during the first 14 d of the subsequent lactation. We hypothesized that both pro- and anti-inflammatory oxylipids would vary based on initiation of mammary gland involution and that pegbovigrastim would affect oxylipid concentrations, particularly those related to leukocytes. A complete randomized blocked design was used to enroll cows into either a PEG treatment group (n = 10) or control group (n = 10; CON). Blood samples were collected -7, -2, -1, 0, 1, 2, 4, 7, and 14 d relative to dry-off and 5, 10, and 14 d postcalving. Samples were analyzed for PUFA and oxylipids in milk and plasma by ultra-performance mass spectrometry and liquid chromatography tandem quadrupole mass spectrometry, respectively. Overall, 30 lipid mediators were measured in both milk and plasma. Repeated measures analyses revealed a significant interaction of treatment by time for milk 8-iso-keto-15-prostaglandin E2, prostaglandin F2α, plasma 8,12-iso-prostaglandin Fα-VI, 11-hydroxyeicosatetraenoic acid, and 12-hydroxyheptadecatienoic acid. The majority of milk PUFA and oxylipids differed significantly during early mammary gland involution and into the early postpartum period. This study demonstrated changes in oxylipids in milk secretions and plasma during early involution, and further investigation may illuminate multiple complex processes and reveal targets for optimization of mammary gland involution.

Cows enrolled in a pilot randomized clinical trial evaluating pegbovigrastim administered to dairy cows at dry-off had reduced incidence of intramammary infection.

OBJECTIVE: The objective of this pilot study was to determine if an alternative dosing schedule of pegbovigrastim (PEG; Imrestor; Elanco Animal Health) affects mammary gland health, rear udder width, or milk production of healthy dairy cows. ANIMALS: 20 pregnant late-lactation Holstein cows in November 2019 through April 2020. PROCEDURES: Cows were randomly assigned to receive subcutaneous injections with either 15 mg of PEG (PEG group; n = 10) or a sham injection with saline (0.9% NaCl) solution (control group; 10) administered 7 days before dry-off and at dry-off. Quarter milk samples were collected for bacterial culture and somatic cells before and after dry-off and after calving. Mammary gland width was assessed before and after dry-off. Daily milk yields were evaluated after calving. RESULTS: The incidence of intramammary infection was 5 times greater for quarters of cows in the control group than for quarters of cows that received PEG. The effect of treatment on somatic cell count was not significant, but the effects of period and a treatment-by-period interaction were identified. Treatment did not significantly affect milk production in the subsequent lactation, but the effects of period and an interaction of treatment by period were identified. Rear udder width after dry-off was not significantly affected by treatment, but an effect of period was identified. CLINICAL RELEVANCE: In this pilot study, cows treated with PEG using an alternative dosing schedule had reduced incidence of intramammary infection and an interaction of treatment by sampling period was observed for milk yield. These results suggest that further studies with larger numbers of cows are warranted.

Serum Vitamin D Is Associated with Antioxidant Potential in Peri-Parturient Cows.

Dairy cows experience increased oxidative stress during periods of transition such as at the cessation of lactation and around the periparturient period, thus increasing disease risk. Despite routine supplementation of transition cow diets with certain vitamins in an attempt to mitigate oxidative stress, there is no currently available data directly linking vitamin supplementation with antioxidant potential (AOP) in transition cows. The objective of this study was to determine the association between serum vitamins and biomarkers of oxidative stress in healthy cows. Blood samples were collected from 240 cows at dry off (DO), close up (CU), and 2-10 days post-calving (DIM2-10). Blood samples were analyzed for vitamins (A, D, E), ß-carotene, reactive oxygen species (ROS), and AOP. Spearman correlations and mixed linear regression models were used to assess associations between vitamins and measures of oxidant status. Vitamin D concentrations were positively associated with AOP at the CU and DIM2-10. Based on the positive association with AOP, additional in-vitro studies were conducted that showed vitamin D mitigated barrier integrity loss in endothelial cells during oxidative stress. These results indicate for the first time that vitamin D may have a role in promoting antioxidant potential in transition dairy cows.

Serum retinol, ß-carotene, and α-tocopherol as biomarkers for disease risk and milk production in periparturient dairy cows.

The effectiveness of using serum vitamin concentrations as biomarkers to predict diseases in dairy cows during the periparturient period is not well known. The objective of this study was to evaluate the association between serum ß-carotene, retinol, and α-tocopherol concentrations and periparturient cow diseases in commercial dairies. We measured serum concentrations of these vitamin-active compounds at dry-off and during close-up (approximately 3 wk before calving) and early lactation (approximately 7 d post-calving), and we examined their association with clinical diseases in the first 30 d in milk. Diseases were diagnosed by trained personnel and recorded using database software. Blood samples were taken from 353 cows from 5 different farms over a 3-yr period. Blood samples were analyzed for ß-carotene, retinol, α-tocopherol, and cholesterol. We built separate mixed logistic regression models for each disease outcome: hyperketonuria, lameness, mastitis, uterine diseases (retained placenta or metritis), and an aggregate outcome. For the aggregate outcome, a cow was considered positive if she had one or more of the following: hyperketonuria, lameness, mastitis, uterine disease, pneumonia, milk fever, or displaced abomasum. Concentrations of all 3 fat-soluble vitamins decreased significantly in early lactation relative to the 2 prepartum sampling times. Serum retinol concentrations at close-up and early lactation were negatively associated with odds of developing postpartum hyperketonuria. At early lactation, cows with uterine disease had lower serum retinol concentrations than cows without uterine disease. Similarly, lower serum retinol concentrations were associated with greater odds of having any one disease in the aggregate outcome. First-test 305-d mature-equivalent milk yield was positively correlated with increased serum α-tocopherol and negatively correlated with ß-carotene concentrations. This study demonstrates the potential for serum ß-carotene, retinol, and α-tocopherol to serve as biomarkers for disease risk.

Effects of Super Nutritional Hepatic Copper Accumulation on Hepatocyte Health and Oxidative Stress in Dairy Cows.

Concerns regarding excessive hepatic copper concentrations in dairy cows have increased. The objective of this study was to determine the association of hepatic copper concentrations with evidence of liver disease. Blood and liver samples were collected at the time of slaughter in cull dairy cows (n=100). Liver samples were analyzed for copper using inductively coupled plasma mass spectrometry and crude fat using liquid-liquid extraction and gravimetry. Serum samples were analyzed for glutamate dehydrogenase, γ-glutamyltransferase, sorbitol dehydrogenase, aspartate aminotransferase activities, and bile acid concentrations. Liver samples were examined histologically for inflammation, fibrosis, and rhodanine staining. Animals were stratified by hepatic copper concentration and samples in the highest and lowest quintiles (Q5 and Q1) were evaluated for oxidative stress. Systemic indices of oxidative stress included serum reactive oxygen and nitrogen species (RONS) and total antioxidant potential (AOP). Tissue-level oxidative stress was assessed by immunohistochemistry using 4-hydroxynonenal (4HNE) and 3-nitrotyrosine (3NIT) stains to score the relative abundance and distribution of oxidized lipid and protein products, respectively. Mean hepatic copper concentration was 496.83 µg/g and median 469.72 µg/g and ranged from 70.56 to 1264.27 µg/g dry tissue. No association was found between hepatic copper concentrations and clinicopathological or histological evidence of hepatic damage or dysfunction. There was a significant increase in the amount of IHC staining of 4HNE and 3NIT in Q5 compared with Q1. Moreover, the IHC staining mirrored the distribution of the copper-specific stain rhodanine. These results demonstrate that cows with elevated hepatic copper concentrations had no evidence of active liver disease but had increased hepatic oxidative stress.

Short communication: Survey of hepatic copper concentrations in Midwest dairy cows.

Previous research from our laboratory and others indicates that liver copper concentrations in dairy cattle are commonly well above those recognized as adequate for the nutritional needs of the animal. It has also been speculated that hepatic copper concentrations have been increasing in recent years. Unlike other species, the threshold at which elevated liver copper concentrations becomes deleterious to hepatocytes is not known for cattle. Therefore, the objectives of this study were 3-fold: (1) to delineate differences in the range and mean dry matter hepatic copper concentration for dairy cattle in a retrospective analysis (January 1, 2007, to December 31, 2015), (2) to investigate hepatic copper concentrations in Midwest cull dairy cattle, and (3) to evaluate histologic changes in hepatocellular morphology in the context of copper concentration in cull cows. Furthermore, microscopic changes in hepatocellular morphology or architecture were examined and scored for evidence of inflammation, fibrosis, necrosis, and abundance of rhodanine-stained granules using hematoxylin and eosin and rhodanine staining. The retrospective analysis found copper concentrations within a range of 3 to 1,963 µg/g, with a mean of 473 µg/g. Hepatic copper concentrations in our retrospective study did not increase with time. In our abattoir analysis, copper concentrations ranged from 15 to 978 µg/g, with a mean of 390 µg/g. This study found that the range and mean hepatic copper concentrations were comparatively less in the current abattoir study than copper concentrations in our retrospective analysis. There was no evidence for hepatocellular changes associated with increased copper burdens in this study population.

Hepatic copper concentrations in 546 dogs (1982-2015).

BACKGROUND: Copper associated hepatitis (CAH) has been increasingly recognized in dogs, and speculation exists that hereditary defects in copper metabolism have been exacerbated by increased environmental copper exposure. However, no broad epidemiological investigations have been performed to investigate quantitative hepatic copper concentrations ([Cu]H ) over time in both dogs that are (predisposed breed [PB]), and are not (non-predisposed breed [NPB]), considered at-risk for CAH. OBJECTIVES: To investigate [Cu]H in dogs and explore temporal, demographic, and histologic associations spanning 34 years. ANIMALS: 546 archived liver specimens. METHODS: Retrospective study. Searches of the Michigan State University Veterinary Diagnostic Laboratory database identified dogs that had undergone hepatic histopathologic assessment. Cases with archived tissue were reviewed and classified by breed, time period, and presence or absence of hepatitis. Inductively coupled plasma mass spectrometry was used to determine [Cu]H . RESULTS: In time period 2009-2015, median [Cu]H were 101 µg/g and 313 µg/g greater than median [Cu]H in time period 1982-1988 for NPB and PB dogs, respectively (P < .001 for both comparisons). The proportion of dogs with [CU]H > 300 µg/g increased in NPB (28% to 49%) and PB dogs (48% to 71%) during these periods (P = .002 for both comparisons). Median [Cu]H in dogs with hepatitis increased 3-fold over time in both NPB (P = .004) and PB populations (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: The frequent recognition of CAH in recent years is likely due to the observed increases in [Cu]H over time. Importantly, effects are not limited to PB dogs.