Make the best use of grazed grass to produce milk at lower cost, especially during the uncertainty at present, says CAFRE Western Dairying Advisers.

While high levels of grass production are being achieved on many farms, the utilisation of grazed grass is more difficult. AFBI data, from trial and on farm results, shows that 12.2 t of grass dry matter (DM) per hectare can be grown on average but only 7.5 t is utilised.

Assess Grass Growth and Cover - The ideal pre-grazing grass cover for dairy cows in a rotational grazing system (paddocks or strip-grazing) is 3000 kg DM/hectare. This is equivalent to a grass height of 8 – 10cm and can sustain a high level of milk production with good compositional quality. The sward recovery is also quicker than when heavier grass covers are grazed. Paddocks should be grazed down to around 1600 kg DM/hectare (4cm).

With grass growth and weather conditions changeable, it is essential to walk the grazing platform at least once a week, either by eyeballing or using a plate meter. This can be recorded with a grass budgeting tool such as Agrinet which allows a ‘grass wedge’ to be established and will highlight predicted periods of grass shortages or surpluses.

Surplus grass can be removed as silage, it is important that this is cut at an early stage even though it is a light crop. This will ensure a leafy regrowth is available for grazing as soon as possible. During periods of grass shortage, cows may be fed additional concentrates or buffer fed silage, until grass is in sufficient supply.

Consider batching cows - In a spread calving pattern herd, consider batching cows. Use milk yields to sort cows into groups:

• Grazing full time; Moderate yielding cows confirmed in calf and late lactation cows.

• Grazing by day and housed at night; Mid lactation cows and those producing up to 30 litres.

• Housed full time, if practised by your particular system; Freshly calved and highest yielding cows.

For block calving cows, in either Spring or Autumn, the herd can be managed as one block for ease of management either for fulltime grazing or grazed by day/housed at night.

Milk From Grass - Grass is a quarter of the cost of concentrates per kilogram of dry matter (kgDM). High quality grazed grass, if managed correctly this month of May, is capable of supporting maintenance plus 20 litres of milk.

To calculate the amount of milk produced from grazed grass for a dairy cow, establish the concentrates fed in kgs, divide by 0.45, to give the milk produced from concentrates and then subtract from the total daily milk yield. For example a cow producing 35 litres and fed 10 kg of concentrates is 10 divided by 0.45 giving 22 litres from concentrates, consequently 35 litres minus 22 litres gives 13 litres from grazed grass. This highlights that this cow is not producing enough from grazed grass and has a higher cost of milk production.

Check out the Dairy Margin Over Concentrate (DMOC) service in DAERA online services under Dairy Benchmarking. Your local CAFRE dairy adviser can assist to get you started with this tool over the phone and internet. The link to DMOC video clip with instructions as to get started is as follows

Energy and Protein Content of Diet - Energy, not protein or minerals, is the most limiting nutrient in the dairy cow. If cows are not milking as well as expected, or milk protein is low, or cows are losing excessive condition, energy is the first nutrient to check.

Spring grass has a higher protein content at 20% than average quality silage at 12%, consequently cows should be fed a lower protein concentrate at grass, 15% to 18% protein on a fresh weight basis. High protein in the diet can result in excessive body weight loss as the cow metabolises the extra protein. Avoid feeding high protein diets during the breeding season to reduce the risk of embryonic loss and poor fertility performance. Dietary protein levels can be monitored through milk urea testing. The optimal is between 20 and 35 mg/100ml.

Lower milk butterfat - In early season, grass is leafy and has a low fibre content and milk butterfat may fall. Cows should be fed a fibre based (sugar beet, soya hulls, citrus pulp) concentrate. This is to reduce the risk of digestive upsets and will help to maintain milk butterfat %. In certain situations it may be necessary to include an acid-buff in the diet to reduce the risk of rumen upsets. As the grazing season progresses, grass quality deteriorates and feeding a cereal based concentrate may be more beneficial.

Managing High Grass Cover - Even the best grassland managers can have grazing swards which become too long for quality grazing, over 3000kgsDM/ha, therefore consider improving grass utilisation by:

• Pre-mowing – weather permitting, cut the grass a day prior to grazing and let the cows pick up the wilted forage from the swathe. Best results are achieved when the grass is cut by a disc mower without a conditioner. This will ensure better grass utilisation and also a high quality regrowth.

• Leader/Follower – this enables higher yielding cows to achieve higher grass intakes and milk yields by allowing the cows to eat the leafy portion of the sward. The stemmy residue can then be grazed down quickly with other stock, e.g. heifers or dry cows.

• Topping - After the second grazing rotation paddocks should be topped if there is an accumulation of stemmy material and poor quality grass around dung pats. Set the topper to cut grass at 5-6cm height.

• Alternate grazing and cutting - Cutting all grazing paddocks at least once during the season leaves a clean sward with an even regrowth and may improve grass utilisation and cow performance later in the season.

Discuss all aspects of Spring grazing with your local CAFRE Western dairying advisers in Co Fermanagh, Olwen Gormley and Christopher Breen and in Co Tyrone, Trevor Alcorn and Jane Sayers, who are available by phone and email. Remember to look after yourselves in this difficult time and keep safe.