Bovine respiratory microbiota
The bovine respiratory microbiome is strongly associated with health and disease and may provide insights for alternative therapy when treating bovine respiratory disease (BRD). The niche-specific microbiome communities that colonise the surface of the respiratory tract consist of a dynamic and complex ecological system. The correlation between the disequilibrium in the respiratory ecosystem and BRD has become a hot research topic. Hence, in a review paper by Chai et al (2022) (Veterinary Researchhttps://doi.org/10.1186/s13567-021-01020-x) the authors summarise the pathogenesis and clinical signs of BRD and the alteration of the respiratory microbiota. They discuss the process of resident microbiota and pathogen colonisation as well as the host immune response. Although associations between the microbiota and BRD have been revealed to some extent, further research is needed to allow a better understanding of the importance of the airway microbiome and its contributions to animal health and performance.
Perhaps now, employing this new research and techniques, we will begin to make significant breakthroughs in our understanding of BRD, allowing better prevention and treatment. For too long we have been treating calves with antibiotics without a good understanding of the complex microbial interactions at play in the respiratory system.
Calf housing in UK dairy herds
Adoption of optimal management techniques for rearing dairy calves has significant effects on their health, welfare, and productivity. This survey by Mahendran et al (2022) (Journal of Dairy Sciencehttps://doi.org/10.3168/jds.2021-20638) aimed to establish current calf management practices in the UK, along with farmer perceptions surrounding different housing types. A survey was distributed online to UK farmers via social media, online forums, and a convenience sample of veterinary practices, and was completed by 216 participants. There was a low level of regular veterinary involvement in day-to-day health decision making for calves (1.4%), highlighting the need for appropriate staff training and standard operating procedures to ensure prudent antimicrobial usage. Restricted calf milk feeding remains highly prevalent in the UK, with most calves fed milk replacer (52.8%), twice daily (87.5%), initially given milk at 4 litres/day (30.6%) or 6 litres/day (21.8%). There was, however, a small number of farmers initially feeding only 2 to 3 litres/day (13.0%). Euthanasia of bull calves (2.3%) and feeding antimicrobial waste milk to calves (3.7%) both occurred on some farms. With regard to housing, use of individual calf pens has reduced from around 60% in 2010 to 38.4% in this study, with this reduction being partly driven by the policy of UK milk buyers. Farmer perceptions indicated that individual housing was thought to help to improve calf health and feed monitoring of calves, suggesting that successful use of group housing requires a higher level of stockmanship. The majority of farmers did not provide fresh bedding to calves on a daily basis (65.3%), and relatively few disinfected both the calf housing (38.0%) and ground (47.7%) between calves, suggesting that hygiene practices may require additional attention in farm management protocols.
Cow-calf contact in New Zealand
Separation of the cow and calf shortly after birth is a common practice on commercial dairy farms around the world, but there are emerging concerns about this practice among citizens and other stakeholders. A study by Neave et al (2022) (Journal of Dairy Sciencehttps://doi.org/10.3168/jds.2021-21047) examined the views of New Zealand dairy farmers toward providing cowcalf contact, particularly the barriers to adopting such a system in a seasonal-calving pasture-based dairy system. Standard farm practice in New Zealand is to remove the calf from the cow around 24 hours (but could be up to 48 hours) after birth. These conventional farmers (n=63) were randomly selected from the database of all dairy farmers in New Zealand and telephone-interviewed using a semi structured interview format. Their responses to questions about providing cow-calf contact (defined as contact beyond the standard practice of 48 hours) were analysed using thematic analysis. Three major themes of concern were identified by these farmers about providing cow-calf contact as follows: (1) poor animal welfare, especially the risk of mastitis in the dam, inadequate colostrum for the calf, increased stress from delayed separation, and lack of shelter for calves while outdoors with the cow; (2) increased labour and stress on staff; and (3) system-level changes required, including infrastructure and herd management. Four small-scale farmers providing cow-calf contact for longer than the standard practice of 48 hours were also interviewed; all permitted contact for at least 4 weeks. These farmers also felt that animal welfare and health were important, and that this was promoted in their cowcalf contact systems. Concerns about colostrum and mastitis, for example, were not raised by these farmers, but they did agree that additional infrastructure and shelter were important considerations for cow-calf contact systems. Some conventional farmers expressed cognitive dissonance in that they theoretically preferred cowcalf contact but could not see it being realistic or practical to implement. Farmers currently providing longer cow-calf contact may be a useful resource for better understanding of how practical and economical cow-calf contact systems could be adopted on commercial farms.