May 2021 Monthly Management

Problems with Dairy Calves at Grass; Weed Control in Grassland; Grass & Grazing

24 May 2021

Problems with Dairy Calves at Grass

It is not unusual to see a proportion of calves failing to thrive compared to the rest of the group when they are out at grass at this time of year. Affected calves are usually described as ‘going backwards’ despite most nutritional and health requirements being met. At present, this particular disorder is unknown as the reduction in calf performance and ill-thrift are difficult to define. One certain point is that farmers should not be confusing this disorder with well- known and recognised conditions that commonly affect calves on grass at this time of year like parasites and coccidiosis. Taking faecal samples and sending them to your vet can rule out such conditions.

Clinical symptoms include the development of severe mouth ulcers, which in some cases, may see up to 50% or more of the mouth ulcerated. Calves will start to scour and continue scouring despite the usual treatments including drips. Severely affected calves will become emaciated and mortality is a high risk at this stage.

Severe mouth ulcers in calves. Clinical symptoms of this disorder.
Figure 1. Severe mouth ulcers in calves. Clinical symptoms of this disorder.

Not all calves in the group will be affected and not every farm will encounter this disorder, with severity of cases varying from year to year although many cases have been noted over the last couple of summers. What we can say for certain about this disorder is that it only occurs where calves are left out on to good quality, lush grass. This grass has a high ratio of leaf to stem and a lower proportion of fibre which makes it highly digestible. The downside to this is that if a calf is unable to digest this grass correctly, it will lead to adverse health implications and hindered performance amongst some calves. Rumen development seems to be a common trait among the cases identified. If the calf’s rumen is not sufficiently developed, it seems to be unable to deal with all the sugars in the lush grass, and the starch in the nut that they are getting. This rapid digestion of feed will cause a drop in pH in the stomach. An abnormal rumen pH leads to acidosis with clinical signs of loose dungs and mouth ulcers characteristic of this. Calves lose condition rapidly and as previously mentioned; conventional treatments are not effective. Although it is more labour intensive, offering some long fibre such as hay or straw even to calves at grass can be very beneficial to calf health to prevent too much of a drop in rumen pH.

At Drinagh we are working to help prevent these calf health issues. Our Drinagh Score 16% Calf Nuts now have added RumiDrive®. RumiDrive® is designed to keep calf performance on track while at grass which is essential in achieving weight gain targets.

RumiDrive® is a sweet-scented powerful buffer which maintains rumen health and encourages a strong early appetite. The inclusion of new generation Diamond V yeast will help to aid the digestion of feed while strengthening the gut wall and maintaining digestive health. Including a well-designed buffer in feeds has been shown to increase rumen pH, feed efficiency and dry matter intake which are crucial for the long-term performance of the animal.

RumiDrive® also includes SuperVit B Pack and Proviflore. SuperVit B provides a full complement of all the B vitamins. Vitamin B is essential for maintaining good health and plays a major role in the metabolism of new cells helping to prevent infection and promoting a healthy gut. Proviflore is a natural oil product designed to ensure that the integrity of the gut is not compromised and helps to naturally fight against the effects of coccidiosis.

Weed Control in Grassland


Best control of docks will be achieved in good growing conditions when docks are actively growing, and nutrients are being transported to new leaves and roots, after first cut is often an ideal opportunity. If seed stalks are seen on the plant or if the dock has diseased leaves, it is better to cut/top or graze and allow re-growth of the docks before applying chemical. Use the highest water rates on the manufacturer’s label for best effects. Allow adequate time between spraying and cutting silage and grazing for the herbicide to work.

Season Long Dock Control

Use of herbicides like Doxstar Pro, Hurler and Pastor Trio will give at least season long control (possibly 2-3 years significant reduction in numbers and re-growth of docks) plus a wide range of common grassland weeds. Where clover is of consequence, Eagle or Prospect may be applied. These products do not harm clover but may check grass growth. These are best applied in good growth conditions and will give season long control. Use highest label rates where rootstocks are well established.


Creeping thistle is a perennial plant and grows mainly from an underground stem and this makes total control difficult with one spray. Yield losses of up to 15% have been recorded but they cause most damage by preventing animals grazing around them. Frequent topping can reduce the root reserves but will seldom eradicate the problem as root fragments can lay viable and dormant for years. This weed is best sprayed with Thisltlex, Forefront, MCPA or Lupo in June before flowering and may need a second treatment later in the season to control any late shooting thistles. In a reseed, both root fragments and seed can cause an explosion of creeping thistles. Spear Thistle only spreads by seed. Each plant lives for 2 years (like ragwort) producing a flatted rosette of leaves in year one and then the familiar ‘tree-like’ structure in year two. Once controlled in the re-seed, it is rarely a problem in grazed fields except after poaching or other sward damage. Topping is not effective to control the growth in year one of their lifecycle (as the thistles are under the cut level) but can be carried out on the second-year growth before seed is set. Chemical control options are similar to creeping thistle.

Grass & Grazing

Kevin McCarthy
The month's featured farmer is Kevin McCarthy, Glounathnaw, Bantry
Date 18/05/2021
Pre-Grazing cover 1500 kg/DM/Ha
Yield 29.8 litres
Fat% 3.91%
Protein % 3.40%
Kgs Milk Solids / cow 2.24
Supplement fed (kg/cow) 4kg

The farm is made up of a mix of reclaimed, high and exposed ground. Due to the nature of this ground plus the harsh wind and weather over the last few weeks - grass growth has been well below normal levels until this week. At present the cows are grazing covers of 1500kg/DM/Ha and being supplemented with 4kg or concentrate.

As growth picks up, the plan is to reduce the feeding rate to 2kg with a rotation length of 20-22 days. Grass quality will be monitored and controlled by taking out paddocks and watching grass covers regularly.


I had 50-60 units of nitrogen out across the grazing block by the first week of April. This was put out in the form of urea and 18-6-12. I am currently following the cows with a mix of either Richland, Sweetgrass or 18-6-12 at a rate of 1 bag per acre.


The breeding start date here was the 10th of May. Two mature Angus bulls are rotated day and night with the cows. Even with the stock bulls I continue to monitor heats and so far, 30% of the herd had been served by the end of week one. All replacements are bought in yearly from the same source.