The 2021 Total Dairy Seminar, held this month in Stratford-upon Avon, brought over 300 farmers, veterinarians and supply trade delegates together for the first time in over two years for a packed programme of lectures and workshops.
Appropriately, with Glasgow’s COP-26 underway at the same time, the seminar examined priorities for dairy business resilience in the face of climate change adaptations, among other subjects. An overall theme from the presentations was that incremental gains in animal health and production efficiency can be good both for profitability and the environment.
Head of sustainability at Map of Ag, Hugh Martineau, advised that that the global scientific consensus is that the world is heading for an unsustainable 4⁰C rise in temperatures without preventative actions – hence the COP-26 aim to restrict the rise to 1.5⁰C by 2050.
In fact, global emissions are reducing against their 1990 baseline, he said. But agriculture’s 10% contribution to the world’s emissions is static, as its natural biological processes make further reductions harder. However, there is potential for the sector to sequester emissions from other sectors of the economy.
As far as ruminant livestock is concerned, the goal is to reduce emissions of greenhouse gases – although we need to improve our systems of accurately measuring the on-farm carbon emissions per unit of milk or beef. At the same time, suppliers of embedded emissions through inputs such as fertilisers and feed should make this data available to farmers. Mr Martineau predicted that digital agriculture software platforms will increasingly play a part in connecting all stages of the supply chain to collect this information, for example incorporating data sources such as BCMS, farm nutrient supplies, milk recording and cull cow/beef processing data.
Map of Ag veterinary consultant James Husband explained that 48% of dairy and beef emissions are from enteric fermentation; 11% from feed; 7% from inorganic nitrogen fertiliser and 4% from land use change through imported feed materials.
Mr Husband said it is difficult to measure accurately the effect of changes to diets and feeding systems on GHG emissions from a farm. But there is a clear correlation between lower herd GHG emissions and profitability. For example, carrying fewer empty or sick cows increases the average milk yield of the herd while reducing emissions per cow. A 30-month first calving average produces 3.8% more GHG than a 24-month average.
Similarly, better forage quality reduces both the need for additional concentrate feed and the GHG emissions – grass silage has a cost of some 120 co2 equivalent/kgDM, while concentrates have a score of 1000 co2eq/kgDM.
There is between 10-15% difference in emissions between good and excellent forage quality – so attention to detail when making forage is essential for carbon efficiency, Mr Husband continued. Maize silage carries less embedded carbon than that from grass since the crop uses less fertiliser – but it may need more protein supplementation at feeding, which adds carbon cost.
In summary, better forage quality is the best way to improve dairy carbon efficiency, followed by reducing herd mastitis levels, age at first calving and the herd calving interval, he stated.
Looking ahead, Mr Husband predicted farmers will be incentivised to capture carbon – and potentially trade in carbon offsets – while COP-26 has shown that methane reduction will become important in future climate change mitigation.
With better dairy herd data on feed, health and nutrients, more targeted interventions will be possible, while genetic advances will also help cattle becoming more efficient, he concluded.
Professor Phil Garnsworthy of Nottingham University spoke on whole farm feed efficiency and methane reduction. He agreed that better grass and forage quality increases carbon efficiency, as does a lower heifer replacement rate – currently only 39% of calves born ever calve themselves – and earlier first calvings. More productive cows emit less methane.
Managers should take care to reduce feed wastage, as poorly maintained feeding systems and equipment can be very wasteful, while ad lib feeding can see 10-15% wasted feed – all of which adds to emissions totals.
Should temperatures continue to rise, heat stress in dairy cows will become more of a problem in the UK, advised Dr Tom Chamberlain, but much of the data available comes from hotter regions such as the US. Cows find it hard to lose heat – they don’t sweat. Higher temperatures result in more panting and less rumination, which can both cause metabolic acidosis, with a longer-term drop in signs of oestrus, conception rates and calf birth weights. Grazed animals are at more risk of heat stress than housed cattle.
Where heat stress is likely, herd managers should ensure ample water and provide shade where possible, reduce fibre in the diet to reduce metabolic heat output; use sodium bicarbonate buffers and probiotics to support the rumen; feed cows in the cooler parts of the day, and consider investing in fans and water misting systems for housing.
Professor Limin Kung of the University of Delaware gave a masterclass in silage making. While most farmers appreciate the importance of excluding air during fermentation and minimising the exposed clamp face during feeding-out, there is still a gap in actual practice. Prof Kung said 8-10% nutrient losses are inevitable even from good systems but can rise to 40% in poorly managed ones. And just 10% spoiled silage in a TMR ration could destabilise the quality of the whole feed.
He detailed the whole silage making process from mowing – wider swaths dry faster; through clamping – 6mm sheets are better than 4mm and two layers better than one; to feeding practices to reduce losses. And new technologies can help, including mobile dry matter testing devices; the ‘silage snap app’ to estimate the effectiveness of crop chopping from a mobile phone; and oxygen barrier sheeting to cover clamps.
However good the silage, Canada’s Daniel Scothorn of Scothorn Nutrition, stressed the need for attention to detail in helping cows maximise their dry matter intake (DMI) to ensure milk yield, quality and profitability.
Such practical measures include all cows always having access to sufficient fresh feed and clean water through regular feeding and feed push-ups; with at least 10cms water bowl space per cow and a daily cleaning habit. Ideally, DMI should be a Key Performance Indicator for herd managers and staff, he advised.
Dr James Breen, veterinary consultant at Map of Ag and Associate Professor at the University of Nottingham delivered two sessions on the control of mastitis in dairy herds
The first session outlined the national “QuarterPRO” scheme designed to easily and rapidly assess the predominant herd infection pattern by using individual cow somatic cell count data and clinical mastitis events and an automated “Pattern Analysis Tool”. This pattern tool software is freely available as a download from AHDB Dairy (https://ahdb.org.uk/quarterpro) and allows producers, veterinary advisors and consultants to ensure any advice given to control new infections is based on the herd PATTERN, with RESOURCES to provide information and that this is ONGOING every three months, hence the name of the scheme “QuarterPRO”. The QuarterPRO scheme is designed to be used for routine monitoring and guidance, with the Mastitis Control Plan remaining available for trained deliverers if more detail is required.
Having talked about preventing the first clinical case of mastitis in a cow’s lactation (always the most important element of mastitis control), Dr Breen then delivered a session on optimizing the outcome of treatment for any first clinical cases of mastitis that do arise, in conjunction with Kath Aplin from Boehringer Ingelheim.
Dr Breen echoed comments made by Prof Andrew Bradley (QMMS Ltd and University of Nottingham) about the importance of antibiotic treatment for the FIRST case of clinical mastitis detected in a cow’s lactation to improve chance of cure. Producers and their veterinary advisors should ensure that ALL clinical cases of mastitis are reported such that cure rate can then be measured using non-recurrence of clinical signs AND individual cow somatic cell count data, for example are the next three cell counts below 200,000 cells/ml following a clinical mastitis event? Factors that are likely to improve the outcome for FIRST cases in a herd will be speed of detection, prompt treatment, duration of treatment in higher cell count herds and the importance of cleaning the teat end with alcohol wipes before inserting the intramammary tubes.
Prof Andrew Bradley discussed the outcomes of very new research looking at predicting the chance of cure for a cow with clinical mastitis and stressed the importance of looking at cow information rather than relying on the results of bacteriology, as even strains of pathogens such as E. coli are able to persist within the udder and cause recurrences of clinical mastitis. Cows that are more likely to cure – and therefore who should receive antibiotic tubes – are younger cows, cows that do not have a history of high cell counts and cows that have not had clinical mastitis in the current lactation, as well as other factors such as time of year and number of quarters affected.
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