Managing your cows during Spring turnout

28th April 2022

Managing your cows during Spring turnout

Spring turnout is a highlight for many farmers, and their cows, a sign of longer days and shorter nights.

It is a change from the winter routine, and with change often comes stress. However, putting cows out to grass has several benefits, like reducing the spend on feed and indoor maintenance and when executed effectively it can lead to improved performance. It is important to remember that poor management of this key transitional period can have negative impacts on performance so it's important to get it right.

Take it easy

Grassy field

The first rotation of all grazing platforms is important to graze off any winter growth allowing for higher quality spring grass to grow. Having an appropriate grazing plan best suited to your farm will help maximise regrowth of paddocks allowing you to achieve your grass coverage targets for subsequent grazing rotations. For example, the second rotation of grass, which many farmers are currently in, swards should be at the 'three-leaf' stage and grazed from 8-10cm to 4-5cm in height to fully utilise the amount of grass available.

It is important to re-introduce cows to grazing gradually. Good preparation is key to ensure that rumen health and function are not hampered and to avoid unnecessary stress on the animal that could negatively affect milk quality, and on farm profitability. It can take up to three weeks for the bacteria in the rumen to adapt to dietary change. Cows should be able to consume 5kg of dry matter (DM) in approximately three hours in suitable swards and weather conditions so even a few hours of on/off grazing by day, when weather conditions allow, will help the rumen adapt to fresh grass, building up to let cows out night and day as weather, and grass growth permits.

Look at your cows

Dairy cows in field

Maximising dry matter intake (DMI) is critical for cows grazing spring grass, to help maintain body condition score (BCS). A reduced BCS after turnout can have negative effects on reproductive performance highlighting how important it is to closely monitor and manage the dietary change to avoid digestive upsets and loss of performance.

It is important to note that after calving down, ideally BCS 3-3.25, cows should not lose more than 0.5 of BCS between calving and reaching peak milk yield. If cows lose more, they are in negative energy balance, which puts significant pressure and stress on the animal to produce milk. Meeting cow energy requirements at the start of the grazing season and into the second rotation is critical for ensuring reproductive performance is not negatively impacted.

Don't cut corners

Relying on grass alone can result in nutritional deficiencies, leading to problems with fertility, herd health and performance. Early spring grass tends to be high in sugars that are highly digestible in the rumen and if too much is consumed it can cause a shift in rumen pH. It is critical to manage energy requirements with concentrate supplementation. Young spring grass also tends to be high in protein, combined with the low fibre content of the grass, can lead to digestive upset and even sub-acute rumen acidosis (SARA).

Fibre is key for maintaining rumination rate and preventing drops in rumen pH from occurring. Rumination time is positively associated with milk production. Hence, providing a buffer or appropriate higher fibre feeds such as straw, beet pulp and hulls, can help to prevent declines in rumen pH and can alleviate the stress and pressure caused by reduced fibre in the diet. Monitoring milk solids could help identify if something is wrong as a drop of 0.3% or more can indicate a problem with digestive function.

SARA causes problems at grass. SARA is seen when rumen pH drops below 5.5. To prevent this from happening as aforementioned, it is critical to supplement cows with a buffer and high fibre feeds. Mag12 is one of the most effective buffers on the market. Rumen soluble magnesium oxide is four times more effective than sodium bicarbonate as a rumen buffer. Mag12 provides a rumen soluble source of Magnesium which causes no irritation in the hind gut of the cow, and is also shown to elevate rumen pH, preventing SARA occurring in dairy cattle grazing spring grass. Trial work carried out by SRUC in 2011, found that cows fed Mag12 had increased milk yield, butterfat, and protein compositions compared to those that were not fed Mag12.

Monitor milk yield and composition

Fresh spring grass tends to have a high level of rumen degradable protein (RDP) that rumen microbes cannot utilise in large quantities and if left unchecked can lead to elevated blood urea nitrogen levels which can cause a reduction in BCS, fertility and hoof health. An unbalanced ratio of RDP to fermentable metabolisable energy (FME) from buffer or concentrate feeding, can limit milk yield and reduce fertility.

Variability in protein levels of grass require supplementation with a high energy, quality concentrate that includes yeast to help increase rumen microbe activity and enhance performance. Devenish yeast on-farm 50 can be used to promote rumen microbe activity and thus increase efficiency and energy utilisation. This increase in efficiency will help prevent fluctuations in milk protein levels which can be experienced when cows are turned out to spring grass.

A new to the Irish market product, Vertan, improves ruminant protein feed efficiency by reducing ruminal deamination. Vartan's effect on rumen flora enables it to work on proteins of the whole ration. Whenever energy is limiting, Vertan comes in to its own - it slows down the breakdown of proteins in the rumen to amino acids and ammonia.

Research has shown that Vertan can increase protein efficiency. There is less nitrogen lost as urea in the urine, meaning less ammonia is produced, causing less stress on the liver. Separate research has shown the increase in reproductive performance whenever blood urea nitrogen levels are low. Incorporating Vertan into the ration has been shown to increase protein efficiency when energy is the limiting factor, something which is often seen throughout the second rotation of the grazing platform.

Certain proteins can be protected from rumen degradation and are known as rumen protected proteins and as the name suggests they are "protected" from breakdown in the rumen leaving them readily available to be absorbed in the small intestine. Rumen protected proteins can have many benefits to dairy cattle like increasing milk yield, improving reproductive efficiency, enhancing protein synthesis and energy utilisation. That's why Devenish developed ByPro, a readily available source of rumen protected soya and the limiting essential amino acid, methionine. ByPro can be incorporated into the concentrate feed or be formulated into the diet, to help alleviate the pressure of early lactation as well as the stressors of increased diet variability during the spring turnout period.

With current stressors and challenges on the supply chain, it is critical that a high-quality, energy dense concentrate is supplemented to cows at grass, particularly in the second rotation of grazing. Remember, reproductive performance is a key pillar and cornerstone of dairy herd profitability. The oocytes that cows realise in the breeding period, are made approximately 60 days prior to ovulation. It is therefore essential to supplement animals with an appropriate amount of concentrate to prevent poor quality oocytes being released. This can have detrimental effects on reproductive performance of the dairy herd.

Stress less: the importance of Magnesium

Magnesium is known as the anti-stressor mineral. Grass staggers is caused by a magnesium deficiency and are particularly prevalent after the spring turnout period due to the low levels of bioavailable magnesium in grass. Symptoms often seen if grass staggers is present are hyperirritability and convulsions, the animal is physically stressed. Ruminant animals are at a disadvantage when it comes to magnesium absorption as they do not digest and absorb it as well as other, non-ruminant animals. Fertilisers can be high in potassium that can further suppress magnesium absorption in cows.

It is therefore advisable to include a magnesium supplement in the feed. Mag12 is a readily available source of magnesium that offers a '3 in 1' prevention for grass staggers, SARA, and milk butterfat suppression.

Mag12 provides a rumen soluble source of magnesium, which can help combat potentially high potassium grazing platforms. It also acts as an excellent rumen buffer that helps maintain rumen pH to prevent SARA and combat the suppression of milk butterfat, often seen during the second rotation of the grazing platform. Mag12 is useful in helping limit the stress associated with the environmental and dietary changes during the turnout period.

The Key Messages

  • Gradually let cows out to graze to give them time to adapt to the change in diet.
  • Look at your cows.
  • Don't cut corners.
  • Monitor milk yield and composition.
  • Ensure cows are getting enough energy through proper supplementation for the breeding season.

If you are experiencing any problems with cows loosing excessive condition, poorer reproductive performance or butterfat suppression during the second rotation and onwards into the spring, please contact our team of ruminant nutritionists who can assist you in rectifying any issues or challenges your cows are experiencing.

Article by Chris Heenan, Trainee Ruminant Sales

References available on request.

Back to Press Releases