THE first of three free CPD webinars on the subject of ketosis took place on 31st January, courtesy of Elanco Animal Health.
The speaker, Mike Steele of Elanco, gave an excellent, up to date overview of subclinical ketosis in the transition dairy cow. The focus in this initial session was on the prevalence of ketosis, the detrimental effects on herd health and the overall costs of the disease.
The first part of the webinar covered the pathophysiology underlying ketosis and other interrelated conditions seen in the transition period (the time from three weeks before calving to three weeks post calving).
There are two forms of ketosis: clinical ketosis which is relatively rare, affecting less than 2% of cows,1 and the subclinical form which has been found to have a prevalence of around 30% of cows.1 This hidden condition is associated with raised levels of blood ketones such as BHBA which then “spill over” and become detectable in the milk and urine.
Having established just how common the condition was, the next part of the session discussed the detrimental consequences to herd health and welfare.
The transition period is a highrisk time for several metabolic and infectious diseases that have a complex inter-relationship. Raised blood levels of ketones have been clearly demonstrated to supress the immune system.2
This in turn predisposes to higher morbidity. The figures given from the latest literature were surprisingly high: raised blood ketones are associated with a three to eight times increase in the risk of a displaced abomasum,3 a doubling in the risk of a retained placenta,4 three times the risk of metritis 3 and a six times increase in the risk of developing cystic ovaries.5
Fertility is adversely affected, with cows taking on average 22 days longer to return to oestrus6 and milk production can be reduced by as much as 300kg in the following lactation.7 Milk quality is also affected, with an increase in fat content and a drop in protein content reflecting a problem with ketosis.8
Probably one of the most startling figures for farmers was a doubling in the risk of culling in the first 60 days post-calving for affected cows.9 It’s clear from the most recent publications that the cost of subclinical ketosis far exceeds the cost of a routine monitoring programme.10
However, as the speaker pointed out, financial losses are not the only costs, it’s recognised that poor herd health is both demoralising and stressful for the farmers. Of equal importance, an increase in infections and metabolic disorders compromises welfare of the cows.
There are a variety of risk factors for subclinical ketosis in a herd, which were discussed in detail, such as a recent epidemic of retained placenta and displaced abomasum, or cows having a poor start after calving with milk fat to protein ratios at 1.5 or above.
Individual cow risk factors include a high body condition score or loss of body condition score during the dry period, a prolonged dry period, first parity, twins and a history of metabolic disease, to name a few that were mentioned.
The speaker said that the key to managing sub-clinical ketosis involved early detection by regular monitoring of transition cows. Recently Keto-test (Elanco), a cowside, milk dip-stick test kit has become available and is ideal for this purpose. The sticks are designed to change colour when milk levels of BHBA equal or exceed 100µmol/l which is equivalent to blood BHBA levels of 1,200µmol/l and indicative of ketosis.
Mr Steele gave some very pragmatic advice about monitoring herds for sub-clinical ketosis, based on experience from Canada with the Keto-test kit. Monitoring can be easily implemented to fit in with routine fertility visits.
Farmers can collect milk samples from all cows that have calved in the past fortnight. The vet can then test the samples with the dip-stick at each routine fertility visit, recording results on charts available from Elanco.
Review needed
A minimum of 12 cows are recommended at each test to provide a reasonable standard deviation for calculating prevalence within a herd accurately. If prevalence is consistently at or over 25% according to the instructions given on Elanco monitoring tool guides, then the management of transition cows needs to be carefully reviewed and improved.
The second webinar (to be covered next month) dealt with monitoring of herds and at-risk individuals in more detail, and how this can be an invaluable tool in maintaining herd health.
This was a great start to a CPD series that gives practitioners the knowledge and tools to change what they do almost straight away, for the benefit of both their clients and the practice.
References
- Macrae, A. I. et al. (2012) Prevalence of clinical and subclinical ketosis in UK dairy herds 2006-2011. World Buiatrics Congress, Lisbon, Portugal.
- Grinberg, Elazar, Rosenshine, Shpigel (2008) ß-hydroxybutyrate abrogates formation of bovine neutrophil extracellular traps and bactericidal activity against mammary pathogenic Escherichia coli. Infec and Immun 76: 2,802-2,807.
- Duffield (2009) Impact of hyperketonemia in early lactation dairy cows on health and production. J Dairy Sci 92: 571-580.
- Leblanc (2004) Peripartum serum vitamin E, retinol, and beta-carotene in dairy cattle and their associations with disease. J Dairy Sci 87: 609–619.
- Dohoo (1984) Subclinical ketosis prevalence and associations with production and disease. Can J Comp Med 48: 1-5.
- Walsh, R. B., Walton, J. S. et al. (2007) The effect of subclinical ketosis in early lactation on reproductive performance of postpartum dairy cows. J Dairy Sci 90: 2,788-2,796.
- LeBlanc, S. (2012) Integrating metabolic and reproductive health in dairy cows. Keynote lecture: World Buiatrics Congress, Lisbon, Portugal.
- Duffield, T. (2000) Subclinical ketosis in lactating dairy cattle. Veterinary Clinics of North America: Food Animal Practice 16: 231-253.
- Leblanc (2010) Monitoring metabolic health of dairy cattle in the transition period. J Repro Dev 56: S29-S35.
- Adapted from Esslemont (2012) The Cost of Ketosis in Dairy Cows. World Buiatrics Congress, Lisbon, Portugal.
