Feeding enriched pasteurised transition milk to calves January 2025 - Final Report
written by Dr Ryan C T Davies, Veterinary Technical Consulting Ltd.
Background
Escalwen farm in Pembrokeshire is a 600-cow pasture-based spring calving dairy herd with a history of high morbidity & mortality in neonatal calves in recent years.
Calves are born from 1 February in a calving season of 10-12 weeks. Approximately 180-200 calves each year constitute replacement animals for the milking herd with the remainder being beef on dairy cross breeds. The farmer is also involved in a Wagyu beef enterprise and 100 of the beef calves constitute Wagyu beef animals. These are of additional financial value to the farm.
Replacement animals are bred to be born at the beginning of the calving block in order to give maximum time for these animals to grow to a sufficient service weight at 1st breeding to align with the calving system, calving down before 24 months old.
The five-year average for morbidity from 2018-2022 was 45% with mortality peaking at 19% in 2022.
Try Out fund project
The basis of the Try Out Fund project was to test and feed pooled, pasteurised transition milk to calves for the first 10 days of life in order to reduce morbidity and mortality of neonatal diarrhoea, and reduce the need for antibiotic treatments.
Dam’s colostrum harvested at milking time (twice daily), pooled and pasteurised using a Holm & Laue MilkTaxi pasteuriser. Pasteurisation was carried out at 60°C for 60 minutes. This transition milk was then fed to all calves from the second feed up to 10 days of age.
In order to account for the variability of the dam’s colostrum, both through maternal variation and dependant on the milking number post-calving, this pooled pasteurised transition mix was tested using an optical refractometer after the pasteurisation cycle.
A minimum standard of 12.5% BRIX was set and if this was not achieved the mix was then enriched using the colostrum powder. Tests on calves for TPI are carried out using the Radial Immunodiffusion Assay (RID) test at the DHHPS laboratory, The University of Edinburgh, Scotland. Samples of the pooled pasteurised transition milk were also tested to determine IgG status using RID testing. Random samples of transition milk were also sent to the DHHPS for RID analysis to monitor the preservation of IgG levels through the pasteurisation process.
Results
There was a failure of passive transfer (FPT) rate of 31% which accounted for persistently high mortality. Transition milk was shown to be of variable quality, most significantly reducing towards the end of the calving period when pathogen challenge was increasing. There was a reduction in morbidity of neonatal calf diseases but most notably NCD (neonatal calf diarrhoea). Mortality resulting from NCD reduced from an average of 9.5% in the 3 years to 2023 to 3% in 2023 and 2024. There was an overall reduction in antibiotic use but most notably a cessation in use of HPCIA’s. Calves fed higher quality transition milk had increased liveweight gain.
Bulk pasteurisation proved a success at Escalwen farm. Pasteurisation of individual bags of bovine colostrum has proved a labour-intensive process on modern large dairy systems. Bulk pasteurisation offers a suitable alternative to assist in disease control.
The producer can mix dams colostrum for administration to all calves with reduced risk of transmission of pathogens such as Mycobacterium avium paratuberculosis, Mycobacterium bovis, Mycoplasma bovis, Salmonella spp. E. coli. A pasteurisation cycle of 60°C for 60 minutes is widely accepted to be effective at destroying coliform bacteria. These bacteria are recommended to be at a level of below 10,000 cfu/ ml in colostrum in order to preserve effective transfer of passive immunity.
It must be noted however that this cycle of pasteurisation cannot be assumed to be completely effective in controlling Mycobacterium and Mycoplasma species. It is likely that pathogen numbers are reduced, but not completely eliminated. To destroy these pathogens a longer heat treatment cycle would be required, or treatment at a higher temperature. This however would compromise immunoglobulin molecules due to increased denaturation of proteins under these conditions. Indeed, it must be accepted that even at a heat treatment cycle of 60°C for 60 minutes, some damage to immunoglobulin molecules may occur. Thus, it is recommended that when using bulk pasteurisation as a method for feeding calves transition milk, regular quantification of IgG numbers is assessed using Radial Immunodiffusion Assay (RID) testing both pre- and post- pasteurisation. This will allow the rate of preservation of IgG concentrations to be assessed. It can also be added that bacteriological culture both pre- and post- pasteurisation periodically will allow further assessment of the pasteurisation process. Thus, it can be monitored that target levels for bacterial contamination are being achieved (<100,000 cfu/ml total bacteria, <10,000 cfu/ml coliforms).
Conclusion
These results show that the supplementation of passive immunity with whole bovine colostrum powder and the feeding of pooled, pasteurised transition milk for the first 10 days of life can reduce the incidence and mortality of NCD, and the use of antibiotics in block calving milk production systems.
Transition milk contains a higher proportion of protein and fat than whole milk, and as such provides additional nutritional benefits. However, the real benefit of feeding transition milk to calves up to 10 days of age comes from its non-nutritive components. These include bioactive factors such as increased levels of growth hormone and insulin-like-growth-factor 1 (IGF-1), relative to whole milk, over 170 oligosaccharides (which act as a carbon substrate for commensal bacteria and also sign pathogens and endotoxins) and non-specific antibacterial peptides such as lysozyme, lactoferrin and lactoperoxidase. The higher IgG antibody content has been shown to be beneficial after the first 24 hours in a calf’s life, as although not absorbed into the circulation can act locally within the gut to reduce pathogen challenge.
All these factors within transition milk can act to preserve gut health and reduce the incidence of disease from diarrhoea causing pathogens, even if calves with FPT (which are inevitable in large block calving systems).
The feeding of transition milk, if the quality is tested and maintained using colostrum powder, as in this ‘Try Out Fund’ study, provides an excellent means of reducing antibiotic usage on farms, and maintaining standards of animal welfare and meeting sustainability targets in modern dairy farming.