Eoin Gerard Ryan

Bovine intramammary infection (IMI) has a negative impact on the dairy industry through economic loss, increased antibiotic use, and reduced animal welfare. Major infectious agents include Staphylococcus aureus, non-aureus staphylococci and mammaliicocci (NASM), streptococci, and coliforms such as Escherichia coli, with the pathogen profile influenced by geography and production system. Strain variability, particularly for S. aureus, also affects the severity and epidemiology of IMI. To investigate the genetic variability of bovine S. aureus and determine if herd-level and individual cow milk quality parameters are associated with specific IMI pathogens or S. aureus genotypes, 20 Irish dairy herds were studied. These herds were classified as problem herds, i.e., high within-herd prevalence of sub-clinical mastitis based on cow level somatic cell counts (SCC) (n = 10), or control, i.e., low within-herd prevalence of sub-clinical mastitis (n = 10). Milk samples were collected from putatively infected primiparous and multiparous cows and subjected to microbiological, milk composition and milk processing analyses. The major pathogens isolated were NASM (37%), streptococci (17%) and S. aureus (13%) with no microorganism recovered from 29% of samples. The majority of S. aureus isolates belonged to Clonal Complex (CC) 97 or CC151 and S. aureus lineage was significantly associated with farm status; CC97 was 10 times more likely to be isolated from a problem than a control herd whereas CC151 was 5.6 times more likely to be recovered from a control than a problem herd. SCC was dependent on the nature of the infecting agent. For all bacterial species, positive samples had significantly higher SCC than samples that were bacteriologically negative, with milk containing S. aureus having significantly higher SCC than all other groups. Infectious agent was also associated with total solids, lactose percentage and rennet coagulation time, although there were no differences between S. aureus lineages in SCC, milk composition or processing parameters. Antimicrobial resistance was rare among the S. aureus isolates, although CC97 and CC8 isolates were resistant to penicillin and ampicillin. Comparative genomic analysis of the S. aureus isolates identified lineage-associated virulence genes. Pan-genome analysis identified a small number of CC97 and CC151 unique genes although no functional enrichment of the unique genes was identified. A number of the lineage-unique genes were associated with mobile genetic elements.

The primary objective of this study was to evaluate the relationship between milk-flow-based parameters, vacuum-based milking variables, and teat health and morphology metrics in relation to both quarter- and cow-level SCC across lactation. Data were collected from 58 cows during 1 wk/mo over an 8-mo period (April to November 2024). Multivariable mixed models were used to identify factors significantly associated with quarter- and cow-level log₁₀-transformed SCC (log₁₀SCC). This study demonstrates associations between vacuum-, milk-flow-, and teat-based milking parameters and SCC at both levels of analysis. Mouthpiece chamber (MPC) vacuum during the total milking period was positively associated with log₁₀SCC at both the quarter and cow levels. Increasing severity of teat-end hyperkeratosis was also associated with higher log₁₀SCC at both levels. At the quarter level, low average milk flow, high peak milk flow, longer dead time, and wider teat diameter were associated with increased log₁₀SCC, whereas at the cow level, shorter high-flow duration showed this association. Together, these findings highlight multiple relationships among machine settings, milk-flow dynamics, and teat condition in determining udder health outcomes. Although this study cannot establish causation because of its observational design and are intended to describe within-system relationships under controlled milking conditions rather than evidence of universal or population-level effects, the results support the value of monitoring of MPC vacuum, assessing milk-flow characteristics, and routinely evaluating teat condition when interpreting SCC patterns in dairy herd.

An 11‐week‐old Holstein Friesian heifer calf presented with a congenital nasal abnormality characterised by an additional, turbinate‐like structure located dorsally on the nasal bridge. Clinical examination of the calf revealed normal respiratory function, with the accessory structure producing mucoid discharge from blind‐ended cavities. Computed tomography demonstrated abnormal turbinates and incomplete bone enclosure consistent with diprosopus dirrhinus. The nasal diprosopus was surgically excised under general anaesthesia with complete closure of the skin defect. Surgery revealed a soft tissue bridge preventing communication with the normal nasal cavities. Histopathology of excised tissue confirmed the presence of respiratory epithelium, cartilage and bone consistent with nasal tissue. At follow‐up, the calf remained clinically normal and continued to thrive. Congenital nasal malformations are rarely reported in cattle, with only two similar cases described previously in Holstein calves. This report adds to the limited literature highlighting the role of imaging in diagnosis and surgical decision making.

The objective of this study was to quantify the method-to-method variation between two widely used field indicators of the end-of-milking vacuum-exposure period (i.e., operational overmilking duration), and to identify cow- and milking-level factors associated with this variation. Operational overmilking was defined using two approaches: (i) MPC vacuum fluctuation patterns collected via VaDia™ recording devices, and (ii) milk flow curves generated from milking system data, with simulated ACR take-off thresholds ranging from 0.2 to 0.8 kg/min. Seven quarter combinations were analyzed to determine their effect on method-to-method variation. Multivariable modelling was used to investigate the factors which influenced the absolute difference in operational overmilking duration (ADOD) between methods, with larger ADOD indicating greater method-to-method variation. All quarter combinations showed large method-to-method variations. VaDia^TM-derived estimates indicated longer overmilking durations and higher milk flow at the onset of overmilking compared with the milk flow curve approach. Our findings showed that a combination of the rear quarters was significantly associated with the lowest ADOD, and that a combination of the front quarters was significantly associated with the highest ADOD. All other combinations did not differ from each other, indicating that combinations including one front and one rear quarter performed similarly, and that recording all four quarters did not improve agreement between methods within this dataset. Milk flow factors associated with increased ADOD included longer low flow times, longer high flow times, longer machine-on times, and increased yield. Vacuum values associated with increased ADOD included high short milk tube vacuum during the full milking, and high mouthpiece chamber vacuum levels during both the full milking and overmilking periods. High short milk tube vacuum during overmilking was associated with decreased ADOD. Wider teat diameters, longer teat lengths, and increased parity were associated with increased ADOD. These findings indicated that vacuum-based and flow-based indicators of operational overmilking capture different aspects of the end-milking process and should be clearly specified when measuring or reporting overmilking in research or commercial milking systems.

High fat-to-protein ratio (FPR) has been used as a proxy measure for negative energy balance (NEB) in dairy herds. This study describes herd-level prevalence of high FPR during early lactation in Irish spring-calving dairy herds and associated risk factors. A retrospective observational study was conducted using 10 years (2014–2023) of national milk recording data from 11,051 unique herds. Median herd-level prevalence of high FPR (>1.4) <30 days in milk (DIM) had a 10-year mean of 14.57% (annual median ranged from 10.81 to 20%), decreasing to 8.10% (annual median ranged from 6.09 to 12.90%) from ≥30 to <60 DIM, with annual variation noted. Multivariable binomial mixed-effects regression models identified factors associated with an increased herd-level prevalence of high FPR including, in the <30 DIM model, months of February and March; genetic predicted transmitting ability (PTA) for Fat kg and an increase in herd percentage of primiparous cows by 10%. In the ≥30 to <60 DIM model, the month of February, a 10% increase in herd percentage of primiparous cows, a 10% increase in herd percentage of parity 4+ cows, and genetic PTA for Fat kg, were associated with increased herd-level prevalence of high FPR. In both models, higher-yielding herds were associated with reduced odds of increased herd-level prevalence of high FPR. These findings suggest that the greatest risk period for high herd-level prevalence of FPR in this system occurs during the spring housing period and shortly after turnout to grass. Higher-yielding herds appeared to have lower risk of NEB and genetic selection for milk Fat kg had an influence on herd-level prevalence of high FPR.

Background: This study describes associations between bulk tank somatic cell count (BTSCC) and farm management practices, parlour management practices and implemented technologies, milking management practices, somatic cell count (SCC) control strategies, and farmer demographics and attitudes around SCC management using a sample of Irish dairy farms. Results: This paper utilised a pre-existing dataset from a farm management and technology survey of 376 commercial Irish dairy farms conducted in 2022. Five mixed models were used to examine associations between variables in each of the five survey sections and log-10 transformed BTSCC (log10BTSCC). Seasonal calving patterns, family members milking alongside survey respondents, and keeping of mastitis treatment records were associated with lower log10BTSCC. Parlour technologies such as automatic cluster removers and automatic washers on the milking machine were associated with significantly reduced log10BTSCC, whereas the presence of backing gates and straight breast rails were associated with increased log10BTSCC. Fore-milking, pre-milking udder preparation and post-milking teat disinfection contributed to lower log10BTSCC. Advice sought from veterinary professionals regarding SCC, multi-faceted approaches to selective dry cow therapy decisions, and utilisation of results from multiple milk recordings were also associated with significantly decreased log10BTSCC. Conclusions: In this study, we successfully established associations between log10BTSCC and farm management practices, parlour management practices and implemented technologies, milking management practices, SCC control strategies, and farmer demographics and attitudes around SCC management. We identified scope for further research on many of the aspects found to be associated with log10BTSCC in this study, particularly in the areas of cow positioning within parlours, fore-milking practices, milk recording, and means of disseminating SCC advice to farmers, particularly around the topics of parlour hygiene and selective dry cow therapy.

Background: This cross-sectional study describes a survey designed to fill knowledge gaps regarding farm management practices, parlour management practices and implemented technologies, milking management practices, somatic cell count (SCC) control strategies, farmer demographics and attitudes around SCC management on a sample of Irish dairy farms. Results: We categorized 376 complete responses by herd size quartile and calving pattern. The average respondent herd was 131 cows with most (82.2%) operating a seasonal calving system. The median monthly bulk tank somatic cell count for seasonal calving systems was 137,000 cells/ml (range 20,000 – 1,269,000 cells/ml), 170,000 cells/ml for split-calving systems (range 46,000 – 644,000 cells/ml) and 186,000 cells/ml for ‘other’ herds (range 20,000 – 664,000 cells/ml). The most common parlour types were swing-over herringbones (59.1%) and herringbones with recording jars (22.2%). The average number of units across herringbone parlours was 15, 49 in rotary parlours and two boxes on automatic milking system (AMS) farms. The most common parlour technologies were in-parlour feeding systems (84.5%), automatic washers on the bulk tank (72.8%), automatic cluster removers (57.9%), and entrance or exit gates controlled from the parlour pit (52.2%). Veterinary professionals, farming colleagues and processor milk quality advisors were the most commonly utilised sources of advice for SCC management (by 76.9%, 50.0% and 39.2% of respondents respectively). Conclusions: In this study, we successfully utilised a national survey to quantify farm management practices, parlour management practices and technology adoption levels, milking management practices, SCC control strategies and farmer demographics on 376 dairy farms in the Republic of Ireland. Rotary and AMS parlours had the most parlour technologies of any parlour type. Technology add-ons were generally less prevalent on farms with smaller herds. Despite finding areas for improvement with regard to frequency of liner changes, glove-wearing practices and engagement with bacteriology of milk samples, we also found evidence of high levels of documentation of mastitis treatments and high use of post-milking teat disinfection. We discovered that Irish dairy farmers are relatively content in their careers but face pressures regarding changes to the legislation around prudent antimicrobial use in their herds.

Lameness is an important production disease in dairy cows worldwide and has detrimental effects on cows' welfare, production, and reproductive performance, thus affecting the sustainability of dairy farming. Timely and effective detection of lameness allows for effective treatment, minimizing progression of disease, and maximizing the prognosis of recovery. Mobility scoring (MSc) is a 4 point (0-3) visual lameness scoring system that is the industry standard in several countries. However, few studies have examined the sensitivity (Se) and specificity (Sp) of MSc to detect foot lesions. The aim of this observational study was to determine the Se and Sp of MSc to detect foot lesions in dairy cattle in a pasture-based system. Five hundred ninety-five primi- and multiparous cows were randomly selected from 12 commercial Irish dairy farms and recruited for the study. Recruited cows were mobility scored and passed through a foot-paring crate where all 4 feet were lifted for examination. The team recorded the anatomical location and severity of any foot lesions present based on appearance only. Then, based on the type and severity of the lesions present, cows were classified according to 3 case definitions case definition 1: Any lesion present; case definition 2: Moderate lesions present (excluding minor lesions expected to have a low probability of affecting gait); and case definition 3: Severe lesions present (only including lesions most likely to result in a detectable gait abnormality). Sensitivity and Sp of MSc was calculated based on a threshold of MSc ≥2, defined as impaired (MSc = 2) or severely impaired (MSc = 3) mobility for each of the 3 case definitions, at the overall level and disaggregated by parity. The overall cow-level lesion prevalence based on the case definition 1 was 0.54 with significant between-herd variation. The overall Se and Sp of MSc for the detection of foot lesions were 0.18 and 0.96, 0.35 and 0.94, 0.43 and 0.94 for the case definitions 1, 2, and 3, respectively. Our findings showed poor Se, but high Sp of MSc for the detection of cows with foot lesions in a pasture-based system.

Background: Penile fibropapilloma is a condition caused by bovine papilloma virus and is frequently encountered in young bulls. Penile fibropapillomatosis is thought to be spread through homosexual mounting behaviour. Fibropapillomas of the penis are painful, often bleed and can impede normal intromission. Treatment may range from allowing time for slow, spontaneous regression to surgical resection but recurrence following surgery is reported by some authors. Case Presentation: Thirty one bulls that were presented to University College Dublin Veterinary Hospital from March 2017 to March 2023 for surgical resection of penile fibropapillomas were included in this retrospective case series. Twenty-seven of the 31 bulls (87%) were under two years of age. The majority (42%) of bulls presented were Hereford, but Angus, Charolais, Holstein-Friesian and Limousin breeds were also seen. Following examination and diagnosis of penile fibropapilloma, regional anaesthesia (xylazine-procaine epidural and internal pudendal nerve block) and standing surgical intervention (resection and cautery) was performed in each case. Phone call follow-up was performed by one author (EET) in all 31 cases and 2 cases out of the 28 that were contactable showed post-surgical recurrence of penile fibropapillomatosis (i.e., 7.1% recurrence rate). Conclusion: This case series summarises the history and presenting findings of 31 bovine penile fibropapilloma cases and describes a regional anaesthetic and standing surgical approach for successful case management.