Papers by Stephen Leblanc
Antibiotics
Antimicrobial resistance (AMR) is an important challenge in public health. Ensuring rational anti... more Antimicrobial resistance (AMR) is an important challenge in public health. Ensuring rational antimicrobial use (AMU) on farms is one of the key components of antimicrobial stewardship. We aimed to describe a sample of Canadian dairy farmers’ personal factors for AMUand their AMR risk perception, and to associate these factors with their attitude toward promotion of prudent AMU. We distributed an online survey among dairy farmers in Ontario and Atlantic Canada (New Brunswick, Nova Scotia, and Prince Edward Island). The questionnaire was designed to solicit information on dairy farmers’ AMU decision-making process, attitudes toward AMU reduction, awareness of AMR, and individual values. We performed a factor analysis on 15 statements related to AMR awareness and AMU reduction and used a logistic regression model to identify variables associated with the probability of disagreeing with the need to increase promotion of responsible AMU in the dairy industry. Respondents’ (n = 193) previ...
Supplemental Figures and Table from Van Schyndel et al. 2021. J. Dairy Sci. The effect of pegbovi... more Supplemental Figures and Table from Van Schyndel et al. 2021. J. Dairy Sci. The effect of pegbovigrastim on early lactation disease, production, and reproduction in dairy cows
TAKE HOME MESSAGES Ketosis is common: several large studies indicate that, on average, more tha... more TAKE HOME MESSAGES Ketosis is common: several large studies indicate that, on average, more than 40% of cows experience ketosis at least once during the first 2 weeks after calving. Even in very well-managed herds, 10% incidence is common. Depending on the severity and timing of onset, ketosis may reduce milk production in early lactation. Ketosis is associated with increased risk of endometritis, anovulation, decreased pregnancy at first AI, and more days to pregnancy. Accurate, practical, and economical cow-side tests are available to detect ketosis in blood, milk, or urine. Most herds would benefit from a routine ketosis screening and treatment program administered once or twice weekly. Cows with ketosis should be treated with 300 mL propylene glycol by drench once daily for 3 to 5 days and then retested the day after the last treatment. Management practices generally recommended for peripartum dairy cows are likely to contribute to prevention of ketosis and to good r...
Early detection of infectious or metabolic disease in transition cows is challenging, particularl... more Early detection of infectious or metabolic disease in transition cows is challenging, particularly as herd size increases. This difficulty is driven by a lack of skilled labour, the cost of labour, or lack of desire to train and supervise people. If technology is to relieve some of this problem, it must be better faster, more accurate, more objective, or cheaper than human monitoring and intervention. While many “precision farming” technologies seek to replace human tasks or assessments completely, a more attainable goal with the potential for widespread application may be to apply, develop, or combine technologies for screening of animals to increase the efficiency of humans’ work or for decision support.
Take Home Messages 8 Essentially all dairy cattle experience a period of insulin resistance, redu... more Take Home Messages 8 Essentially all dairy cattle experience a period of insulin resistance, reduced feed intake, negative energy balance, hypocalcemia, reduced immune function, and bacterial contamination of the uterus soon before, or in the weeks after calving. 8 Health through the dry period and early lactation is a major determinant of reproductive performance for months after. 8 Retained placenta, metritis, and endometritis are strongly associated with immune function in the transition period. 8 High non-esterified fatty acid (NEFA) (> 0.4 mmol/L) in the last 7 to 10 days before expected calving is associated with increased risk of displaced abomasum (DA), retained placenta, culling before 60 days in milk, and less milk production in the first 4 months of lactation. 8 Subclinical ketosis (serum β-hydroxybutyrate (BHB) > 1200 to 1400 µmol/L) in the first or second week after calving is associated with increased risk of DA, metritis, clinical ketosis, endometritis, prolonged postpartum anovulation, increased severity of mastitis, and lower milk production in early lactation. There are several validated and practical tools for cow-side measurement of ketosis. Metabolic Challenges in Peripartum Dairy Cows and Their Associations with Reproduction This paper reviews the importance of energy metabolism in transition dairy cows, its associations with disease and reproduction, and strategies for monitoring cows under field conditions during this critical time.
Journal of Dairy Science, 2017
Treatment with granulocyte colony-stimulating factor (G-CSF) increases polymorphonuclear cell (ne... more Treatment with granulocyte colony-stimulating factor (G-CSF) increases polymorphonuclear cell (neutrophil) count and enhances neutrophil function in the periparturient cow. Prepartum undernutrition was hypothesized to reduce the effect of a commercially available recombinant bovine G-CSF product (pegbovigrastim) on neutrophil count and function. Hence this study was undertaken to test the effect of undernutrition for approximately 1 mo before calving on the innate immune response to pegbovigrastim. Cows (n = 99) on pasture were blocked by expected calving date and body condition score and randomly assigned in a 2 × 2 factorial design. The first factor was that cows were fed to exceed energy requirements prepartum (full feeding) or restricted to approximately 85% of prepartum energy requirements (restricted feeding). The second factor was that at approximately 7 d before expected calving date, half the cows in each feed group were injected with pegbovigrastim and the remaining half were injected with saline. Treatments were repeated on the day of calving. Blood samples were collected preand postcalving for complete blood count, biochemistry, and in vitro assessment of neutrophil function including phagocytosis, myeloperoxidase release, and oxidative burst. Prepartum energy restriction resulted in lower body weight, a higher proportion of cows with elevated concentrations (i.e., >0.4 mmol/L) of fatty acids, and higher average β-hydroxybutyrate concentrations before calving relative to fully fed cows. Treatment with pegbovigrastim increased the total white cell, neutrophil, lymphocyte, and monocyte counts. Pegbovigrastim treatment resulted in increased release of myeloperoxidase by neutrophils. Prepartum feeding group did not have an effect, and no feeding group × treatment interaction was observed for any of the white cell counts or functional tests. We concluded that peg-bovigrastim treatment results in significant increases in neutrophil count and enhances neutrophil function as indicated by increased myeloperoxidase release. The response to pegbovigrastim was not affected by restricted prepartum energy intake.
Journal of Dairy Science, 2014
Injuries are a widespread problem in the dairy industry. The objective of this study was to deter... more Injuries are a widespread problem in the dairy industry. The objective of this study was to determine the prevalence of and explore the animal-based and environmental factors associated with hock, knee, and neck injuries on dairy cows in freestall housing in Ontario and Alberta, Canada. Freestall dairy farms in the provinces of Ontario (n = 40) and Alberta (n = 50) were visited for cross-sectional data collection. A purposive sample of 40 lactating Holstein cows was selected for detailed observation on each farm. Cows were scored for hock, knee, and neck injuries on a 3-or 4-point scale, combining the attributes of hair loss, broken skin, and swelling and with a higher score indicating a more severe injury. The highest hock and highest knee score were used in the analysis. Animal-based and environmental measures were taken to explore which factors were associated with injury. Overall, the prevalence of cows with at least one hock, knee, and neck injury was 47, 24, and 9%, respectively. Lame cows had a greater odds of hock injury [odds ratio (OR) = 1.46] than nonlame cows, whereas cows with fewer days in milk (DIM) had reduced odds of hock injury compared with those >120 DIM (OR = 0.47, 0.64, and 0.81 for <50, 50-82, and 83-120 DIM, respectively). The odds of hock injury was lower on sand (OR = 0.07) and concrete (OR = 0.44) stall bases in comparison to mattresses. Conversely, the odds of knee injury was greater on concrete (OR = 3.19) stall bases compared with mattresses. Cows in parity 1 (OR = 0.45 and 0.27 for knee and neck injury, respectively) and 2 (OR = 0.49 and 0.40 for knee and neck injury, respectively) had lower odds of knee and neck injury compared with cows in parity 4+. Low feed rail heights increased the odds of neck injury (OR = 76.71 for rails between 128 and 140 cm and OR = 43.82 for rails ≤128 cm). The odds of knee injury was greater on farms where any cows were observed slipping or falling when moving into the holding area for milking (OR = 2.69) and lower on farms with rubber flooring in the alley along the feed bunk compared with bare concrete floors (OR = 0.19). These results demonstrate that individual animal characteristics, as well as barn design and animal management, are associated with hock, knee, and neck injuries. These data can help to guide investigations into causes and prevention of injuries.
Immune function is suppressed in periparturient dairy cows, and risk of infectious and metabolic ... more Immune function is suppressed in periparturient dairy cows, and risk of infectious and metabolic disease is increased. Several studies have shown that transition cows supplemented with vitamin E in feed and/or parenterally had decreased risk of retained placenta (RP) or mastitis. However, these benefits are not universally reproducible and may depend on the animals baseline vitamin E and selenium status and other factors. Additionally, a fraction of animals will have hypersensitive reactions to parenterally administered vitamin E. This study investigated the effect of vitamin E on the incidence of periparturient health problems when administered subutaneously to prepartum cows.
1 Centre for Public Health and Zoonoses, University of Guelph, Guelph, ON, Canada, N1G 2W1. 2 Dep... more 1 Centre for Public Health and Zoonoses, University of Guelph, Guelph, ON, Canada, N1G 2W1. 2 Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada, N1G 2W1. 3 Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University College of Veterinary Medicine, Ames, IA 4 York Health Economics Consortium, University of York, York, YO10 5NQ, United Kingdom
Journal of Dairy Science, 2006
This paper describes some of the major points of progress and challenges in health management of ... more This paper describes some of the major points of progress and challenges in health management of dairy cattle in the last 25 yr. A selection of the leading contributors in the field is acknowledged. Specific advances in the areas of transition cow management, epidemiology, udder health, applied immunology, housing design, calf health, and health-monitoring tools are described. The
Journal of Dairy Science, 2007
The objectives of this research were to determine the prevalence of the anovulatory condition wit... more The objectives of this research were to determine the prevalence of the anovulatory condition within a temperate region of North America and identify cow-level and herd-level risk factors for this condition. A total of 1,341 cows from 18 herds were classified as cycling or anovular based on skim milk progesterone concentration determined at 46 and 60 ± 7 d in milk. Calving history, periparturient disease incidence, body condition score, milk ketone concentration in the first 2 wk of lactation, and first 305-d mature-equivalent milk projections were recorded. Reproductive and culling information was retrieved monthly from the Dairy Herd Improvement Association. The cow-level prevalence of anovulation was 19.5%, with a herd-specific range from 5 to 45%. Accounting for the effect of clustering at the herd level, cows experiencing a difficult calving, cows with twin calvings, displaced abomasum, and cows with subclinical ketosis in the first week after calving were at greater risk for diagnosis of anovulation. Anovular cows within herds using ovulation synchronization programs were inseminated at the same time postpartum with a 6-percentage point reduction in the probability of pregnancy relative to cycling herdmates (29.7 vs. 35.9%, respectively), whereas anovular cows in herds breeding based on observed estrus were inseminated 8 d later and suffered a 10-percentage point reduction in the probability of pregnancy at first insemination (20.3 vs. 30.5). Time to pregnancy was delayed in anovular cows by 30 d (156 vs. 126 d). Using survival analysis, the impact of anovulation decreased with time. The daily probability of pregnancy (hazard ratio) was similar to cycling cows by 165 d in milk. The results underline the important associations of peripartum health with reproductive function and performance.
Journal of Dairy Science, 2012
Journal of dairy science, 2013
Surgical correction of left displaced abomasum (LDA) is common in lactating dairy cattle. Despite... more Surgical correction of left displaced abomasum (LDA) is common in lactating dairy cattle. Despite the growing acceptance that abdominal surgery is painful, few cows are administered analgesia following LDA surgery. The objective of this research was to examine the effect of administering a label dose of ketoprofen on physiological and behavioral indicators of pain in dairy cattle. Holstein cows were enrolled in a field study following LDA surgery. Surgery was performed using the standing right flank (RF) approach or the paramedian (PARA) approach. Using a triple-blind randomized trial, each animal was assigned to receive either 3mg of ketoprofen/kg of body weight or saline (the equivalent volume) by intramuscular injection immediately following surgery and 24h postoperatively. Physiological parameters (heart rate, respiration rate, and rumen motility), blood β-hydroxybutyrate (BHBA) levels, and an assessment of cow attitude were measured on the day of surgery, and at 2 follow-up vis...
Journal of dairy science, 2013
Parturition is a necessary event for production in dairy cattle, and assistance at calving is com... more Parturition is a necessary event for production in dairy cattle, and assistance at calving is common. There is limited use of nonsteroidal antiinflammatory drugs for the alleviation of calving pain and a paucity of research on the effects of these drugs on postpartum health and performance. This randomized triple blind clinical trial involved Holstein cows (n=42) and heifers (n=61) that experienced an assisted parturition. These animals received either 1 injection of meloxicam (0.5mg/kg of body weight) or placebo subcutaneously 24h following calving. Outcome measures included dry matter intake (DMI) and milk production for the first 14d in milk, blood metabolites sampled over 12d, health events for the first 60d in milk, as well as lying and feeding behavior 24h following injection. Continuous data were analyzed using multivariable regression models. Binary outcomes were analyzed using a mixed logistic model with cow modeled using a random intercept. This study failed to show any si...
Journal of Dairy Science, 2015
Lameness is a severe welfare problem and a production-limiting disease in dairy farming. The obje... more Lameness is a severe welfare problem and a production-limiting disease in dairy farming. The objectives of this study were to determine prevalence of lameness and investigate cow-and herd-level factors associated with lameness in dairy cows housed in freestall barns in 3 Canadian provinces. A purposive sample of 40 Holstein-Friesian cows was selected from each of 141 dairy farms in Québec, Ontario, and Alberta. In total, 5,637 cows were scored once for lameness (presence of limping when walking). Data collected included information on individual cows (hock lesions, claw length, body condition score, parity, days in milk, and milk production), management practices (floor and stall cleaning routine, bedding routine, and footbath practices), and facility design (stall dimensions, stall base and bedding type, width of feed alley, flooring type, and slipperiness) hypothesized to be risk factors for lameness. Multilevel mixed logistic regression models were constructed (including farm as a random effect and province as a fixed effect). Herd-level lameness prevalence ranged from 0 to 69% (mean = 21%). Lameness prevalence increased with increasing parity; compared with first parity, cows in parity 2, 3, and ≥4 had 1.6, 3.3, and 4 times, respectively, higher odds of being lame. Furthermore, the odds of lameness were 1.6 times greater in cows with low body condition score (≤2.5) than in cows with a higher body condition score. In addition, injured hocks and overgrown claws were associated with 1.4and 1.7-fold increased odds of being lame, respectively, whereas every 1 kg increase in daily milk production was associated with a 3% decrease in the odds of being lame. Lameness prevalence was higher in herds with ≤100 cows, but lower in barns with a sand or dirt stall base, or with bedding ≥2 cm deep. Cows exposed to very slippery floors had 2 times the odds of being lame compared with cows exposed to nonslippery floors. We attributed the wide range of lameness prevalence to the great variability in facilities and management practices among farms. Finally, we inferred that the prevalence of lameness could be decreased by improving management of multiparous, thin, or injured cows and by adopting management practices intended to improve cow comfort, namely the floor's slip resistance and the stall's lying surface.
animal
Aspects of neutrophil function are diminished or dysregulated in dairy cows in the weeks just bef... more Aspects of neutrophil function are diminished or dysregulated in dairy cows in the weeks just before and after calving, which appears to be an important contributor to the occurrence of retained placenta, mastitis, metritis and endometritis. The timing and mechanisms by which specific elements of neutrophil function are impaired are only partially understood. Oxidative burst capacity is the element of neutrophil function most consistently shown to be impaired in the week after calving, but that observation may partially be biased because oxidative burst has been studied more than other functions. There is sufficient evidence to conclude that the availability of calcium and glucose, and exposure to elevated concentrations of non-esterified fatty acids or β-hydroxybutyrate affect some aspects of neutrophil function. However, these factors have mostly been studied in isolation and their effects are not consistent. Social stressors such as a competitive environment for feeding or lying ...
Frontiers in veterinary science, 2018
The ability of automated activity monitoring (AAM) systems to detect estrus is influenced by mult... more The ability of automated activity monitoring (AAM) systems to detect estrus is influenced by multiple variables. The luteal phase (LP) preceding estrus has been shown to be important for hormones release, and behavior during estrus in ruminants, but its impact on activity as measured by AAM systems has not been studied. The objective of this study was to investigate the impact of the length of the preceding LP on the intensity and duration of estrus as measured by AAM, and on the expression of estrogen receptor alpha (ERα) in the endometrium. A total of 60 cows between 46 and 53 days in milk were assigned to either a normal or a short length LP. Length of the LP was insured by the use of hormonal synchronization programs. Cows in both treatments were matched on parity, milk production, body condition score (BCS), and lameness score (assessed at enrolment). Expression of ERα receptors in the endometrium were evaluated by nuclear staining by immunohistochemistry of biopsies. Estrus wa...
Journal of dairy science, 2018
The use of pain control for disbudding and dehorning is important from both an animal and industr... more The use of pain control for disbudding and dehorning is important from both an animal and industry perspective. Best practices include the use of local anesthetic, commonly given as a cornual nerve block (CNB), and a nonsteroidal anti-inflammatory drug. The proportion is decreasing, but many dairy producers do not use local anesthesia, perhaps in part due to lack of knowledge of the CNB technique. Although this skill is typically learned in person from a veterinarian, alternative methods may be useful. The objective of this trial was to determine if there were differences in the efficacy of online training (n = 23), hands-on training (n = 20), and a combined approach (n = 23) for teaching producers to successfully administer a CNB and disbud a calf. The primary outcome was block efficacy, defined as a lack of established pain behaviors during iron application. Secondary outcomes were background knowledge (assessed by a written quiz), CNB and disbudding technique (evaluated by rubric...
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Papers by Stephen Leblanc