Using a target trial approach to evaluate the role of hyperketonemia in sole ulcer and white line hoof lesion development.

This observational cohort study enrolled cows from 7 freestall dairy herds in Minnesota and Wisconsin. The objective was to estimate the causal role of hyperketonemia on new sole ulcer and white line hoof lesions (SUWL). Multiparous cows were enrolled at the time of their precalving hoof trim, at the end of their previous lactation. Enrolled cows were hoof trimmed twice: precalving between 90 to 21 d before calving (n = 2,037), and postcalving between 21 to 150 d after calving (n = 1,408). We trained 7 commercial hoof trimmers, employed by the farms, in lesion identification to standardize lesion recording. Hoof trimmers conducted therapeutic trimming as well as diagnosing and treating lesions. After parturition, cows between 3 and 16 d in milk were tested once weekly for hyperketonemia using a hand-held ketone meter. Farm staff and research personnel conducted the ß-hydroxybutyrate (BHB) testing. Cows were classified as hyperketonemic (HYK+) if they had a blood BHB ≥1.2 mmol/L or hyperketonemia-negative (HYK-) if blood BHB <1.2 mmol/L. At the precalving hoof trim, 15.6% of cows trimmed had a lesion and 1.9% of cows had a SUWL; thus, cows with a SUWL were excluded from further analysis (n = 38). At the postcalving hoof trim, 25.8% of cows trimmed had a hoof lesion, and 3.6% of cows had a SUWL. The most prevalent lesions at the pre- and postcalving hoof trims were digital dermatitis and corkscrew lesions. The incidence of hyperketonemia among cows was 21.1% (421/1,999) and the incidence on farms ranged from 5.7 to 29.1%. After excluding cows due to being hoof trimmed outside our designated window, the multilevel logistic regression model for the odds of SUWL at the postcalving hoof trim included 1,209 cows (HYK+ = 257/1,209; SUWL = 42/1,209). The odds of having SUWL in HYK+ was 0.66 (95% confidence interval: 0.29, 1.49) times the odds of that for HYK- cows. For cows diagnosed with a lesion (digital dermatitis, corkscrew, toe, foot rot, or other lesion) at their precalving hoof trim (n = 199), the odds of having SUWL for HYK+ cows were 0.43 (95% confidence interval: 0.05, 3.92) times the odds of that for HYK- cows. The wide range of compatible causal estimates suggest that hyperketonemia likely has a limited role in the development of SUWL in cows with or without a hoof lesion precalving. Future research should investigate other transition period factors such as inflammation or structural changes to the foot that may have a causative role in the development of SUWL.

Promoting farm advisor engagement and action toward the improvement of dairy cattle lameness.

Lameness represents a significant management challenge in the dairy industry worldwide. In addition to farmers, many advisors are involved in lameness management, including veterinarians, hoof trimmers, and nutritionists. These advisors support farmers through lameness prevention practices, treatments, and advice, but little is known about how advisors view others' roles and the extent to which they work together. This study used qualitative participatory methods to facilitate the formation of lameness advisory groups among 13 advisors (4 veterinarians, 5 hoof trimmers, and 4 nutritionists), with the aims of promoting advisors' engagement with one another and documenting their perceptions of the benefits and challenges of the research activities through semi-structured interviews and thematic analysis. Participants shared predominantly positive views toward the project and voiced appreciation about the quality of discussions and the opportunity to connect and build relationships with other advisors. Participants reported improved communication with others via sharing reports and farm information, as well as increased confidence in reaching out to other advisors. Reported challenges included time constraints and discomfort in leading the lameness advisory group meetings. Difficulties were also found in bringing issues to farmers' attention when they might not align with the farmers' goals or priorities, as well as participants' questioning other advisors' knowledge and intentions. This study describes a promising avenue of facilitating advisor engagement, although more work is needed to determine whether such engagement translates to a reduction of lameness on farms.

Dairy farmer, hoof trimmer, and veterinarian perceptions of barriers and roles in lameness management.

Lameness is a leading animal welfare concern in the dairy industry. Multiple stakeholders are involved in lameness management on a dairy farm, including farmers, hoof trimmers, and veterinarians. This study sought to explore perceptions of lameness, perceptions of roles in lameness management, and barriers to improved lameness management in these groups. Fourteen homogeneous focus groups were held in Minnesota, Wisconsin, and New York from April 2017 to March 2020; 5 with farmers (n = 31), 4 with hoof trimmers (n = 32), and 5 with veterinarians (n = 25). The 1-h facilitated discussions were audio-recorded, transcribed verbatim, and common themes identified through thematic analysis. Lameness was perceived by participants as a complex health problem and one in which the connections between pathogenesis, facilities, and management were not always well understood or easy to change. The complexity of the problem encompassed the lack of agreement on a definition of lameness, normalization to its signs, and the interconnectedness of lameness with other health and management issues. These issues appeared to contribute to resignation by participants that lameness was inevitable. Despite shared concerns about lameness among these groups, respondents reported a lack of communication, especially between hoof trimmers and veterinarians. Participants also voiced a desire to work together more productively, with hoof trimmers and veterinarians valuing the ability to deliver a consistent message to farmers. These findings suggest a need for increased efforts to facilitate collaboration between farmers, hoof trimmers, and veterinarians to improve lameness management on dairy farms.

Short communication: The effect of storage conditions and storage duration on milk ELISA results for pregnancy diagnosis.

The objective of this study was to evaluate the effect of storage temperature and time from sample collection to analysis on test classification of a commercially available ELISA for diagnosis of pregnancy using the measurement of pregnancy-associated glycoproteins (PAG) in milk samples from dairy cows. Few studies have evaluated the effects of sample handling on milk PAG results. Using a repeated-measures study design, we evaluated sample storage at 5 temperatures: 37°C, 22°C, 4°C, -20°C, or -80°C. Sample aliquots from 45 cows (20 with a pregnant test result, 10 open, and 15 recheck) were stored for 4, 7, 14, 28, 60, 90, or 365 d. The measured PAG level was influenced by storage duration and condition. Samples stored for 365 d had a slightly increased PAG level, whereas samples stored for all other durations showed a slight decline in PAG level compared with the initial result. The reason for an increase in PAG level following long-term storage is not known. This will not affect dairy producers using the test but may be important in samples stored for research applications. The changes in PAG level were small and within the expected variation for this test. Fewer than 6% of samples changed in classification and, as expected, they were samples near the test interpretation cut-points.