Top Tips for Turnout

By Anna Millar, Ruminant Technical Manager, Trident MicroNutri

Many dairy farmers are currently taking the welcome opportunity to turn cows out and reduce costs through utilising grass. However, turnout always introduces significant dietary changes for dairy cows. The transition from a silage-based diet to the highly variable grass-based diet can cause significant upheaval within the rumen, affecting the cow’s ability to perform and remain healthy. Additionally, estimating grass nutritional value and supply can be challenging, but with some careful planning and accurate measurements, we can help support cows’ energy and nutrient supply as they are turned out to grass.

Gradual Turnout

To minimise the cow stress and the degree of upset in the rumen, it is important to turn cows out gradually. It can be very tempting to open the gates and allow the cows to graze all day immediately, however this incurs a major diet change and can result in serious imbalance within the rumen, having a significant effect on digestion, health, and performance.

It is a good idea to turn cows out for one hour on the first day, and then increasing gradually by one hour each day thereafter. As a guide, cows will consume around 1kg of good quality grass dry matter for every hour spent at grass. Factor this into your TMR feeding as part of the introduction to grazing. Remember, if conditions become wet, grass intakes per hour will be less than 1kg DM.

Grazing Covers

It is important to assess sward height and density prior to turnout, and continually throughout the grazing season. This allows informed decisions to be made on grazing allocation, utilisation and appropriate buffer feeding where required. The target cover pre-grazing is 2,500kg DM/ha, and cows should be allowed to graze this down to 1,500kg DM/ha. The most accurate way to measure grazing covers is to use a plate meter.

According to the most recent GrassCheck report from AFBI, grass growth rates were forecast to be around 17kg DM/ha/day. This is in line with the 10-year average, so we’re off to a steady start this year.

Buffer Rations

Often, the desire to exploit low-cost grass leads to over-estimates of its feed value and dry matter intake, leading to reduced performance and poor health and fertility. A well-balanced buffer ration of suitable quality and quantity is critical for supplying enough energy and nutrients to the cow. In particular, fresh-calved cows and higher-yielding cows are unable to meet energy requirements for maintenance, plus milk, from grass alone.

Buffer feeding should be flexible, changing the quantity fed daily according to the availability and quality of grass. For example, if cows are not able to graze to target residual cover of 1,500kg DM/ha (i.e. grass is being left behind in the field), buffer feeding should be reduced. Similarly, if grass dry matter decreases due to rainfall, buffer feeding should be increased to satisfy requirements.

Good rumen health can be proactively encouraged by ensuring adequate levels of digestible fibre in the ration. Chopped straw is a useful addition if available. This ensures sufficient intakes of fibre to encourage good rumen function and balance of rumen microbes, helping to mitigate the risk of milk fat depression. The inclusion of AcidBuf rumen buffer and Vistacell live yeast is highly beneficial in optimising rumen conditions for the reduction of the risk of acidosis and milk fat depression.

Finally, don’t forget minerals! Spring turnout is a high-risk period for grass staggers so adequate magnesium supplementation is particularly important.

With careful management and monitoring of grazed grass and supply of a high-quality, well-balanced buffer ration, utilisation of grass can be maximised, with limited production losses and improved overall lactation profit.  For more information on planning for a successful grazing season, please contact us on 02894 473478 or complete the contact form and we will get back to you!