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Kay O'Sullivan September/October Update 2023

Managing redstart & red clover

Managing redstart & red clover

  • Managing redstart (catch crop) at feeding
  • Addressing a phosphorus deficiency in the redstart crop
  • Red clover management for the autumn
Vaccinations, FECs and IBR sampling

Vaccinations, FECs and IBR sampling

  • First shot of respiratory disease vaccines given
  • FEC samples being monitored
  • Cows will be blood sampled for IBR
Latest weights

Latest weights

  • Cows and calves were weighed for SCEP
  • Heifer performance is very good with 200 day weights of 272kg, bulls were 284kg
  • Weaning efficiency of cows is 41% (target 42%)

Animal Nutrition

Kay sowed redstart, a kale/rape hybrid brassica crop on her farm this June. The aim of sowing it is to provide a high energy feed to her out wintered weanlings and to some finishing cattle over winter. A derogation was required from Kay’s organic licensing body before sowing the crop.

Weaned calves will start grazing the crop in November this year. Prior to grazing, a mineral bolus will be administered to the calves containing iodine, selenium, copper and cobalt as catch crops are usually low in these minerals. Kay will introduce the crop gradually to them by using a strip wire and allocating a small amount daily. Good quality silage bales (>70% DMD) will be provided as a fibre source as well. In the event of frosty weather, the strip wire fence will not be move until the crop has thawed out, as nitrates can build up when frozen and be toxic to animals. Similarly, the crop will not be grazed after it starts to flower in spring as this can also be poisonous.

Redstart growing this year

Figure 1: This year’s redstart crop

Kay ensures that fresh water is provided to the weanlings at all times. The 1.6ha field that Kay selected for the redstart crop is surrounded by three other grass fields (4.3ha total) which will act as a lie back from the crop in an effort to minimise any damage to the soil during grazing and to satisfy cross compliance rules.

View a video from Kay’s farm here;

A grass margin also surrounds the feed area and there is a grass lie back left in the paddock, so only approximately 1ha is covered with redstart. The redstart appeared to strike well in the field and after a few weeks a red/purple tinge started to appear in the leaves. The soil pH is 7 and the soil is in index 4 for K, but only in index 1 for P. It was likely symptoms of a phosphorus deficiency so rock phosphate was spread (11% P), which is an approved organic fertiliser. The recommended spreading rate is 200-300 kg/ha and it was spread at a rate of 250 kg/ha across the entire paddock. Slurry would have been beneficial was Kay was conscious not to damage any of the crop by travelling with heavy machinery so the rock phosphate was spread using a gator and small spreader.

Phosphorus deficiency in redstart

Figure 2: Symptoms of phosphorus deficiency in the redstart

The red clover crop is growing very well and will need to be cut again before the winter. Kay’s plan is to mulch it in as she has sufficient silage for the winter and it will avoid any further nutrient offtakes. The field has received FYM and 2,000 gallons of cattle slurry per acre to supply P and K back to the crop. The aim is to cut it next April/early May 2024.

Red clover regrowths

Figure 3: Red clover crop which was cut on 5th September


Animal Health

The calves have been given their vaccinations against RSV, Pi3 and Mannheimia (Bovipast) and IBR (live vaccine). They will receive a booster shot 4-6 weeks later so that they have the full course at least 2 weeks before weaning.

FEC samples were taken on 12th September from the calves and showed that they are negative for coccidia, lung worms and gastro intestinal worms so no dose is required. They will be monitored for signs of lung worm and another sample will be taken in 4-6 weeks.

Kay has applied to the National Beef Welfare Scheme and the cows will be blood tested to check their IBR status as part of this.

Finishing cattle grazing multi species

Figure 4: Finishing cattle grazing a multi species sward


Kay weighed her cows and calves for the SCEP scheme on 14th September. The ICBF weaning performance report shows that the heifer calves (5) had a 200 day weight of 272kg, well ahead of the target 250kg. They gained 1.21 kg/day since birth. The bull calves (14) were 284kg, slightly behind the target of 300kg. They gained 1.26kg/day since birth until 200 days of age.

The average weight of the heifers on the day was 218kg and the bulls averaged 234kg. They average birth date was 6th April for the heifers and 12th April for the bulls.

The average weight of the cows was 701kg and this ranged from 508kg to 1000kg! The weaning efficiency (200 day weight as a percentage of cow live weight) was 41%, which is close to the target of 42%. It ranged from 31% to 75% for a cow that had twins.

Suckler cow calf pair

Figure 5: Cow #105 that weighed 1000kg, with her bull calf weighing 294kg after gaining 1.49 kg/day since birth