The effect of dystocia on physiological and behavioral characteristics related to vitality and passive transfer of immunoglobulins in newborn Holstein calves.

The objective of this study was to examine the effect of calving difficulty or dystocia on the vitality of newborn calves and its association with blood pH, the apparent efficiency of immunoglobulin G (IgG) absorption (AEA), and weight gain. A total of 45 calving events (N = 48 calves) were monitored from the first sight of fetal membranes. All calves were assessed at the time of first attaining sternal recumbency (SR), at 2 and 24 h, and at 7 and 14 d of age. Measurements included time to SR, rectal temperature, respiration and heart rate, analysis of blood gases and other blood measures, suckling response, time to standing, passive transfer of IgG, and weight gain. Calves were separated from their dam 2 h after birth and fed a commercial colostrum replacer containing 180 g of IgG by esophageal tube feeder. Calves born following dystocia had lower venous blood pH and took longer to attain SR and attempt to stand than those born unassisted. Duration of calving interacted with the number of people required to extract the calf by pulling as a significant predictor of pH at SR. No association was found between pH at SR and AEA. However, reduced AEA was found in calves that were female and in calves that did not achieve SR within 15 min of birth. A longer calving duration, being born in July or August rather than June, and a shorter time spent standing in the first 2 d of life were significantly associated with reduced weight gain to 14 d. It was concluded that factors at calving impact the physiology, vitality, and subsequent weight gain of newborn calves.

L'objectif de la présente étude était d'examiner les effets des difficultés au moment du vêlage ou dystocie sur la vitalité de veaux nouveaunés et l'association avec le pH sanguin, l'efficacité apparente d'absorption des immunoglobulines G (IgG) (EAA), et le gain de poids. Quarante-cinq vêlages (N = 48 veaux) furent surveillés à partir de la première visualisation des membranes foetales. Tous les veaux furent évalués au moment de la première fois qu'ils étaient en décubitus sternal (DS), à 2 et 24 h, et à 7 et 14 jours d'âge. Les données recueillies incluaient le délai pour atteindre le DS, la température rectale, les rythmes respiratoire et cardiaque, l'analyse des gaz sanguins et d'autres mesures sanguines, la réponse de tétée, le délai pour se tenir debout, le transfert passif d'IgG et le gain de poids. Les veaux furent séparés de leur mère 2 h après la naissance et nourris par tube oesophagien avec un substitut commercial du colostrum contenant 180 g d'IgG. Les veaux nés suivant une dystocie avaient un pH sanguin veineux plus bas et ont pris plus de temps pour atteindre le DS et tenter de se lever que ceux nés sans assistance. La durée du vêlage a interagit avec le nombre de personnes requis pour extraire le veau en tirant comme un prédicteur significatif du pH à DS. Aucune association ne fut trouvée entre le pH à DS et l'EAA. Toutefois, une EAA réduite fut notée chez les génisses et chez les veaux qui n'étaient pas en DS à l'intérieur d'un délai de 15 min suivant la naissance. Une durée plus longue du vêlage, une naissance en juillet ou août plutôt qu'en juin, et un temps plus court à se tenir debout pendant les deux premières journées de vie étaient associés significativement avec un gain de poids moindre après 14 j. Il a été conclu que des facteurs au moment du vêlage ont un impact sur la physiologie, la vitalité et le gain de poids à venir de veaux nouveau-nés.(Traduit par Docteur Serge Messier).

Association of bovine respiratory disease or vaccination with serologic response in dairy heifer calves up to three months of age.

OBJECTIVE: To investigate the association of bovine respiratory disease (BRD) or vaccination with serologic response in calves. ANIMALS: 94 Holstein calves. PROCEDURES: To assess the association between BRD and antibody titers, 38 calves < 3 months old that were treated for BRD were matched with 38 untreated calves. To investigate the effect of vaccination on antibody titers, 24 calves were randomly assigned to be vaccinated against bovine respiratory syncytial virus (BRSV), bovine viral diarrhea virus types 1 and 2, bovine herpesvirus type 1 (BHV1), and parainfluenza virus type 3 at 2 weeks of age (n = 6), 5 weeks of age (6), and both 2 and 5 weeks of age (6) or were assigned to be unvaccinated controls (6). Blood samples were obtained at I, 2, 5, and 12 weeks for determination of serum neutralization antibody titers against the vaccine viruses, bovine coronavirus, and Mannheimia haemolytica. Antibody rates of decay were calculated. RESULTS: Calves with initial antibody titers against BRSV < 1:64 that were treated for BRD had a slower rate of anti-BRSV antibody decay than did similar calves that were not treated for BRD. Calves with high initial antibody titers against BRSV and BHV1 had lower odds of BRD than did calves with low initial antibody titers against those 2 pathogens. Vaccination at 2 or 5 weeks of age had no effect on the rate of antibody decay. CONCLUSIONS AND CLINICAL RELEVANCE: Clinical BRD and the serologic response of dairy calves were associated with initial antibody titers against BRSV and BHV1. Serologic or clinical responses to viral exposure may differ in calves with low passive immunity.

An investigation of the effects of ketoprofen following rumen fistulation surgery in lactating dairy cows.

Post-operative pain management following rumen surgery is not common practice. We examined the effect of providing the pain medication ketoprofen to dairy cattle following the first stage of a rumen cannulation surgery, which involves an incision in the body wall and exteriorizing and clamping the rumen. The results of this study provide clear evidence that the first stage of the surgery was painful and ketoprofen at the time of and 24 h following surgery, alleviated some, but not all, of the post-surgical pain. Pain mitigation should be included when performing flank surgery in cattle.

Une enquête sur les effets du kétoprofène administré à des vaches laitières après une chirurgie de fistulisation du rumen. Ce n'est pas pratique courante d'administrer des analgésiques suite à la chirurgie du rumen. Cette étude a examiné les effets du médicament kétoprofène chez les vaches laitières après la première étape d'une chirurgie de fistulisation du rumen. Cette chirurgie consiste à faire une incision sur le côté gauche de l'abdomen pour ensuite sortir une partie du rumen de l'abdomen et de le fixer avec une attache. Les résultats de cette étude démontrent que la première étape était douloureuse et que l'administration du kétoprofène, à la fin de la chirurgie, ainsi qu'après 24 h, a atténué une partie de la douleur chirurgicale sans toutefois l'enlever complètement. L'administration d'analgésiques devrait faire partie intégrante du traitement lors des chirurgies abdominales chez les bovins.(Traduit par les auteurs).

Newborn calf vitality: risk factors, characteristics, assessment, resulting outcomes and strategies for improvement.

Dystocia is a stressful and traumatic event for both the cow and calf. As the prevalence of dystocia has increased over time, attention has been focused on maintaining the health and longevity of the cow. Lack of vitality in the newborn calf may go unnoticed and result in short or long-term implications for calf health and performance. A prolonged or assisted delivery may increase birth stress in calves causing a variety of effects including injury, inflammation, hypoxia, acidosis, pain and an inability to maintain homeostasis. Each of these effects can further contribute to a reduced state of vitality in the newborn calf. Newborn vitality is essential to the health, survival and welfare of the calf. If the calf is not vital at birth, it may be unwilling or unable to get up and suckle colostrum in a timely manner. Early colostrum intake improves passive transfer of immunoglobulins, energy uptake and thermoregulation. Intervention may be required to assist these calves such as respiratory and thermal support, manual feeding of colostrum or the administration of non-steroidal anti-inflammatory drugs to aid health and long-term survival. However, more research is needed to determine ways in which newborn calf vitality can be assessed and improved in order to reduce the increased risk of morbidity and mortality and long-term effects on performance.

Short communication: a comparison of 2 nonsteroidal antiinflammatory drugs following the first stage of a 2-stage fistulation surgery in dry dairy cows.

Postoperative pain and its management following fistulation surgery in cattle are poorly understood. The purpose of this study was to compare 2 nonsteroidal antiinflammatory drugs (NSAID) as potential postoperative pain management treatments following the first stage of a 2-stage fistulation surgery. A randomized complete block design trial was conducted in dry Holstein cows (n=10) following fistulation surgery. Ketoprofen (3mg/kg of body weight i.m.) was administered on the day of surgery and 24 h later, whereas meloxicam (0.5 mg/kg of body weight s.c.) was administered once only on the day of surgery. Outcomes evaluated at 0, 2, 9, 24, 26, and 33 h postsurgery were heart rate, respiration rate, rectal temperature, and infrared temperature around the surgical site. Outcomes evaluated on the day of surgery and d 1 following surgery and compared with the average for the 4d before surgery were lying activity (total lying time, total time spent lying on the left side, and percentage of time lying on the left side) and feed intake. A difference was observed in dry matter intake on d 1 but this effect was not different on d 0 compared with presurgical averages. A difference was observed in time spent lying on the left side and a difference was observed in heart rate following the first stage of fistulation surgery compared with presurgical averages. The infrared temperature readings around the surgical site were significantly greater in the hours following surgery compared with presurgical averages. The respiration rate increased over time after 24h postsurgery compared with presurgical values. Although it was clear that the surgery is painful, the drug effects were more difficult to explain. On d 0 and 1, the meloxicam-treated cows ate 3 kg more but spent 101 min/d less time lying on their left side compared with ketoprofen-treated cows. The first stage of a 2-stage fistulation surgery was considered painful based on changes in heart rate, respiration rate, infrared temperature readings, dry matter intake, and time spent lying on the left side. It is clear that left flank surgery is painful and that NSAID can improve outcomes associated with that pain, but we cannot make recommendations as to which NSAID to choose based on these results.

Effects of meloxicam on milk production, behavior, and feed intake in dairy cows following assisted calving.

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 significant effects of treatment on DMI, milk production, blood metabolites, or health events. A possible explanation for the lack of treatment differences could be that the meloxicam was administered too late after calving. Meloxicam increased feeding time as well as bunk visit frequency in the 24h following injection. Regardless of treatment, animals that had retained fetal membranes produced less milk and had higher serum haptoglobin concentrations. Future research is warranted to examine the effects of antiinflammatory drugs administered closer to the time of calving on health and production.

Short communication: use of a mechanical brush by Holstein dairy cattle around parturition.

Grooming is a normal behavior that may contribute to relief of stress. The purpose of this study was to investigate the effect of access to a mechanical brush on auto-grooming behavior in parturient cows. The hypothesis was that cows would increase the total time spent scratching using the brush if they had access to a brush around the time of calving, whereas auto-grooming would be lower for the brush group compared with the no-brush group. The use of a mechanical brush was analyzed both in a group-housed pen (72 to 48 h before calving) and in an individual maternity pen (6h before to 6h after calving) in 16 multiparous Holstein cows. In the maternity pen, cows were randomly assigned to have access to the brush or not. The provision of a mechanical brush in the individual maternity pen did not change the amount of time spent auto-grooming but cows did use the brush before calving and after the calf was removed. Despite being housed in pens containing a brush, cows failed to use it when the calf was present. However, cows with access to a brush spent more time licking their calves in the first hour postcalving (ß=8.7 min; 95% confidence interval: 1.5, 15.8) than cows that did not have access to a brush. Regardless of treatment, cows increased the time spent auto-grooming and scratching following separation of their newborn calf (ß=1.4 min; 95% confidence interval: 0.46, 2.3 and ß=0.07 min; 95% confidence interval: 0.02, 0.12, respectively). Further research is warranted to investigate possible benefits of mechanical brush devices at the time of calving, particularly for cows that experience difficult calving and require manual or mechanical assistance.

The effect of administering ketoprofen on the physiology and behavior of dairy cows following surgery to correct a left displaced abomasum.

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 ß-hydroxybutyrate (BHBA) levels, and an assessment of cow attitude were measured on the day of surgery, and at 2 follow-up visits (visit 1=3 ± 0.9 d and visit 2=9 ± 1.2 d postsurgery; n=175). Milk production and culling were recorded for all cows enrolled in the study. Producers assessed their cows' attitudes and appetites daily for the first 3 d following surgery. A subset of cows (n=37) were fitted on the day of surgery with a 3-axis accelerometer on the hind leg to assess lying behavior. Continuous and binary outcome data were analyzed using multivariable mixed linear and mixed logistic models, respectively, with cow modeled as a random effect. Ketoprofen did not alter the physiological measures, BHBA levels, or behavioral outcomes measured. Cows subjected to RF surgery had longer lying times [model coefficient ß=228.9 min; 95% confidence interval (CI): 122.2 to 335.6] in the first 3 d following surgery, and lower heart rates (ß=-9.4 beats/min; 95% CI: -12 to -6.9 beats/min) at the follow-up visits, compared with animals that underwent PARA surgery. Regardless of surgical procedure, BHBA decreased from surgery day to visit 1 (ß=-1.9 mmol/L; 95% CI: -2.1 to -1.7) and visit 2 (ß=-2.0 mmol/L; 95% CI: -0.2.2 to -1.8). Producer reports indicated that animals that received ketoprofen were more likely to begin eating when provided fresh feed during the first 3 d following surgery compared with those that received saline (odds ratio=4.8; 95% CI: 0.97 to 23.8). These results indicate that PARA surgery may be more painful relative to lying down than the RF approach. The apparent differences in appetite or attitude in cows that received ketoprofen reported by producers warrant further investigation.

Metabolic predictors of post-partum disease and culling risk in dairy cattle.

A retrospective study was conducted to determine the relationship between serum non-esterified fatty acids (NEFA), ß-hydroxybutyrate (BHBA), glucose and calcium (Ca) with the occurrence of displaced abomasum (DA), clinical ketosis and culling in Holstein cows. Eight hundred and forty-nine cows from 16 farms were sampled weekly for the first 3 weeks post-partum. The cows were under clinical observation from calving until 60 days in milk (DIM) and during this time there were 22 cases of DA, 31 cases of clinical ketosis and 39 cows were culled. Elevated concentrations of BHBA were associated with DA, clinical ketosis and culling. In the first week after calving, cows with serum BHBA ≥1000µmol/L had 13.6 times greater odds of developing DA than cows with lower values. Serum NEFA and BHBA concentrations during week 1 were associated with the subsequent occurrence of clinical ketosis. The odds of clinical ketosis were 6.3 times greater in cows with serum NEFA ≥ 1.0mmol/L in the first week after calving. In addition, cows with BHB ≥1200µmol/L in the first week after calving, were at 4.7 times greater risk of developing clinical ketosis. In the first and second weeks after calving the serum Ca concentration was associated with subsequent culling. In addition, cows with NEFA concentration ≥ 1.0mmol/L were 3.6 times more likely to be culled within the following 2 months. The study indicated that early post-partum serum BHBA, NEFA and Ca concentrations have potential as indicators of disease and culling risk in dairy cows.

Obesity in rhesus and cynomolgus macaques: a comparative review of the condition and its implications for research.

Obesity is an increasingly important health issue in both humans and animals and has been highly correlated as a risk factor for hyperglycemic conditions in humans. Naturally occurring obesity has been extensively studied in nonhuman primates with a focus on the development of biomarkers for characterizing overweight individuals and tracking the progression of obesity to conditions such as type 2 diabetes mellitus. Animal models have provided a basic understanding of metabolism and carbohydrate physiology, and continue to contribute to ongoing research of obesity and its adverse health effects. This review focuses on spontaneous obesity in rhesus and cynomolgus macaques as a model for human obesity and type 2 diabetes mellitus, including associated risk factors for the development of obesity and obesity-related health conditions. Little is known about preventive measures to minimize obesity while maintaining a healthy colony of macaques, and numerous complexities such as social status, feeding behaviors, timing of feeding, food distribution, and stress have been identified as contributing factors to overweight body condition in both single and group housed nonhuman primates. As in humans, increased body weight and obesity in macaques affect their overall health status. These conditions may interfere with the suitability of some animals in various studies unrelated to obesity.

Survey of prevalence of overweight body condition in laboratory-housed cynomolgus macaques (Macaca fascicularis).

Excessive weight gain has been reported to occur in captive cynomolgus macaques with little to no change in diet. Overweight body condition can result in development of hyperglycemia and type 2 diabetes and should be avoided. The purpose of this survey was to assess the prevalence of overweight cynomolgus macaques in North American research facilities, including breeding colonies and short-term and long-term facilities, and to describe current methods used to assess body condition. The survey consisted of 51 questions covering animal population demographics, body weight and body condition scoring, feeding, and behavior. Voluntary participants included veterinarians and animal care managers. Respondents from 13 facilities completed the survey, and information was collected on 17,500 cynomolgus macaques. The majority of surveyed facilities housed juvenile and young adult macaques. The reported prevalence of overweight (greater than 10% of ideal body weight) animals ranged between 0% and 20% and reportedly was more frequent in animals younger than 10 y. Most facilities had weight reduction strategies in place. Despite these programs, a significant proportion of animals were reported as being overweight. The results of this survey demonstrate that most North American facilities housing cynomolgus macaques recognize the importance of tracking body condition regularly. However, implementing effective weight reduction programs may be difficult in captive housing environments. Because of the potential for adverse health effects, facilities should have a means of regularly tracking body weight as well as an action plan for managing overweight animals.

Reference limits for biochemical and hematological analytes of dairy cows one week before and one week after parturition.

Since dairy cows during the transition period have multiple endocrine and metabolic changes, it is necessary to determine the reference limits of laboratory analytes in normal transition cows. Reference limits for the weeks before and after calving were determined in dairy cows. Animals that had adverse clinical outcomes after calving and cows that were culled or had mastitis within the first 7 days after calving were excluded. All biochemical analytes (beta-hydroxybutyrate, fatty acids, glucose, cholesterol, urea, calcium, and phosphorus) were statistically different between precalving and postcalving groups. The hematological analytes were not significantly different except for eosinophils. The data from precalving and postcalving cows were significantly different from reference limits in a university-associated laboratory derived from early- and mid-lactation cows. Different reference limits for precalving and postcalving dairy cows should be determined for biochemical analytes to ensure appropriate interpretation of results.

Assessment of bovine mammary chemokine gene expression in response to lipopolysaccharide, lipotechoic acid + peptidoglycan, and CpG oligodeoxynucleotide 2135.

During intramammary infections pathogen associated molecular patterns (PAMPs) induce an inflammatory response, recognized clinically as mastitis. Recognition of PAMPs by mammary cells leads to the production of the pro-inflammatory cytokines, TNF-alpha and IL-1beta. These cytokines augment the secretion of various chemokines that are responsible for directing the host cellular immune response, and consequently the outcome of infection. Previous research has shown that gram-negative and gram-positive bacteria elicit different types of innate immune responses. The purpose of this study, therefore, was to characterize the expression of various chemokine genes in bovine mammary gland explants in response to lipopolysaccharide (LPS), peptidoglycan (PTG) combined with lipotechoic acid (LTA), and CpG oligodeoxynucleotide (CpG-ODN) 2135 representing gram-negative bacteria, gram-positive bacteria, and bacterial DNA, respectively, to determine if these PAMPs induce different chemokine gene expression patterns. Explants from 3 Holstein cows were cultured with 10 microg/mL of LPS, LTA + PTG, or CpG-ODN 2135 for 6 and 24 h. Total RNA was extracted and the expression of CXCL8, MCP-1, MCP-2, MCP-3, MIP1-alpha, and RANTES genes was measured by real-time polymerase chain reaction (RT-PCR). Lipopolysaccharide significantly induced MCP-1, MCP-2, and MCP-3 expression, and slightly increased CXCL8 gene expression. The combined PAMPs, LTA + PTG, on the other hand, significantly induced MCP-1 gene expression, and slightly increased MCP-3 expression. No significant expression differences for any of the chemokine genes were observed in explants stimulated with CpG-ODN 2135. These results demonstrate that PAMPs associated with different mastitis-causing pathogens induce chemokine-specific gene expression patterns that may contribute to different innate immune responses to bacteria.

Evaluation of prepartum serum cholesterol and fatty acids concentrations as predictors of postpartum retention of the placenta in dairy cows.

OBJECTIVE: To identify serum biochemical and hematologic variables, as measured in the week before parturition, that predict postpartum retention of the placenta (RP) in dairy cows. DESIGN: Retrospective cohort study. ANIMALS: 1,038 cows in 20 commercial dairy herds. PROCEDURES: Serum concentrations of fatty acids (FAs), beta-hydroxybutyrate, cholesterol, glucose, urea, and calcium and blood leukocyte, neutrophil, lymphocyte, monocyte, and eosinophil counts were determined. These variables were evaluated for an association with development of RP by use of a multivariate logistic regression model. Parity, season of parturition, existence of twins or dystocia, body condition score, and vitamin E treatment were included in the model as covariates. RESULTS: High serum concentrations of cholesterol and FAs were associated with an increased odds of RP. There was a 5% relative increase in the odds of RP for each 0.1 mmol/L increase in cholesterol or FAs concentration in the week before parturition. Season of parturition and twinning were also identified as risk factors. CONCLUSIONS AND CLINICAL RELEVANCE: These associations indicated that prepartum energy metabolism contributes to the development of RP. Serum concentrations of cholesterol and FAs may be useful to identify cows with a metabolic abnormality or energy imbalance that might predispose them to RP and should be interpreted in conjunction with clinical risk factors such as twinning, dystocia, or parturient paresis.

Research and teaching of dairy cattle well being: finding synergy between ethology and epidemiology.

Epidemiology is a tool used to identify and quantify risk factors that contribute to the state of health or disease. In addition, the maintenance of health and recognition of nonhuman animal welfare are both key principles of health management. Animal welfare and ethology provide important contributions to our ability to understand and improve health. As such, there can be a strong connection between the disciplines of ethology and epidemiology. This connection becomes a synergy through collaborative research. At the University of Guelph, and at other institutions, dairy health management research efforts involving collaborations between faculty trained in ethology and epidemiology have led to refined and improved research programs, improved access to funding, and a broader extension audience. Furthermore, these collaborations have enhanced teaching programs and facilitated the integration of ethology and welfare topics throughout the veterinary medical curriculum. The paper provides the basis and context for the synergy between ethology and epidemiology and describes examples of teaching and research programs built upon this synergy for the enhancement of dairy cattle well being.

The relationship between herd level disease incidence and a return over feed index in Ontario dairy herds.

The objective of the current research was to examine the association of herd level disease incidence with the return over feed (ROF) (milk income minus feed cost) herd profit index offered through Canwest Dairy Herd Improvement. The lactational incidence risks (LIR) for displaced abomasum, retained placenta, clinical mastitis, milk fever, clinical ketosis, and lameness submitted by producers (n = 48) were similar to previous reports. However, there was no negative association of clinical disease LIR's with ROE Subclinical ketosis and subclinical mastitis cumulative incidence were determined during the early postpartum period by using a cow-side test for betahydroxybutyrate in milk and the California Mastitis Test, respectively. Subclinical mastitis was not associated with ROE However, a unit increase in the cumulative incidence of subclinical ketosis was associated with a decrease of dollars 0.015/cow/day in the ROE The results highlight the economic significance that subclinical ketosis may have in Ontario dairy herds.

A comparison of serum harvesting methods and type of refractometer for determining total solids to estimate failure of passive transfer in calves.

Monitoring the passive transfer of immunoglobulins from colostrums particularly in noncentrifuged samples can be useful for calf health management programs. The results of total solids refractometry from centrifuge and noncentrifuge harvested sources of serum were highly correlated (R2 = 0.95). Results from a digital and a hand-held refractometer were highly correlated (R2 = 0.96).

Assessment of antimicrobial transfer from treated to untreated mammary gland quarters by use of high-pressure liquid chromatography for detection of cloxacillin in milk samples from nonlactating dairy cows.

OBJECTIVE: To determine whether half-udder intramammary infusion of cloxacillin results in transfer of cloxacillin from treated to untreated mammary gland quarters within nonlactating cows, and, if so, at what concentrations, and to determine whether selection of ipsilateral versus diagonal-contralateral quarters for treatment affects cloxacillin transfer among quarters. ANIMALS: 20 Holstein-Friesian cows from a dairy herd. PROCEDURES: A within-cow half-udder comparison trial was used in which 2 of 4 mammary gland quarters (ipsilaterally or diagonally) received an intramammary infusion of cloxacillin on day 1 of the nonlactating period. Three days later, milk samples were taken from all untreated quarters and high-pressure liquid chromatography was used to detect and quantify milk cloxacillin concentrations. RESULTS: Cloxacillin was detected in 25% of all untreated mammary gland quarters. Mean cloxacillin concentration in untreated quarters was below minimum inhibitory concentrations for targeted mastitis pathogens. No significant difference in cloxacillin concentrations was found in the ipsilateral or diagonal treatment groups. CONCLUSIONS AND CLINICAL RELEVANCE: Within-cow half-udder comparison trials are valid for antimicrobial trials in nonlactating cows, although transfer of antimicrobials does occur in trace concentrations. Ipsilateral or diagonal-contralateral treatment designs perform similarly. This type of design is economical for researchers, although care must be taken to account for within-cow clustering of mammary gland quarter data.

Monensin might protect Ontario, Canada dairy cows from paratuberculosis milk-ELISA positivity.

Our objective was to define the role of monensin sodium in protecting cows from being milk-ELISA positive for paratuberculosis in Ontario, Canada dairy herds. In total, 4933 dairy cows from 94 herds were enrolled in this cross-sectional study. Forty-four of the enrolled herds were selected purposively by their herd veterinarian and another 50 herds were randomly selected from a local milk production-recording agency. A herd-management survey was completed on each farm during the months of May through August 2003. During this same time-period, composite milk samples were collected from all lactating cows and tested with a milk-ELISA for antibodies to Mycobacterium avium subspecies paratuberculosis. Analyses were stratified according to the paratuberculosis history of the herds. In the 48 herds in which paratuberculosis had not been diagnosed before, the use of calf hutches and monensin in milking cows were both associated with reduced odds of a cow testing positive (OR=0.19 and 0.21, respectively). In the 46 herds with a prior history of paratuberculosis, feeding monensin to the breeding-age heifers was associated with decreased odds of a cow testing positive (OR=0.54). Monensin use might be associated with milk-ELISA positivity, but its impact on the transmission of paratuberculosis remains unknown.

Characterization of bacterial populations recovered from the teat canals of lactating dairy and beef cattle by 16S rRNA gene sequence analysis.

Bovine mastitis is of major concern to the dairy industry worldwide. The bovine teat canal is the primary route through which pathogens enter the mammary gland. The microflora of the teat canals of dairy and beef cattle was investigated by analysis of 16S rRNA gene sequences. The goal was to examine the global difference between dairy cattle, which are sanitized on a regular basis, and beef cattle, which receive little sanitary management. A diverse population of 16S rRNA gene sequences was recovered from both the dairy and the beef herd samples, with diversity higher in the beef sample. Analysis revealed the presence of 90 operational taxonomic units (OTUs) among 156 sequences, with 45 OTUs in the dairy sample and 53 OTUs in the beef sample. Only eight OTUs were common to both samples. Members of the classes Clostridia and Bacilli dominated both samples, followed by Actinobacteria and Proteobacteria. The dairy sample contained a cluster (20/80 clones) of Staphylococcaceae members, seven of which were identifiable as coagulase-negative Staphylococcus species. The beef sample was dominated by members of the genus Clostridia, many of which have not been previously cultured. The results suggest that the microorganisms present in the bovine teat canal are more diverse than previously described.