June 2021 Monthly Management

Fertiliser for Second Cut; Phosphorous & Potash Off-takes in Surplus Bales; Preventing Lungworm Losses at Grass; Grass & Grazing

22 June 2021

Fertiliser for Second Cut

Second cut silage will require approximately 100Kg N/ha (80 units/acre) with high perennial ryegrass content swards (recently reseeded ground) requiring higher levels of nitrogen compared to older swards.

Make allowances for N, P and K values of slurry used. If the first cut did not receive slurry, then an extra application should be targeted later in the year – stick to normal levels (2000 gallons/ acre) of slurry application when saving your second cut. Excess potash from slurry that is carried in with the crop will lead to a range of problems at the feed-out stage next winter. These include milk fever, retained cleanings and other metabolic disorders through depressed magnesium absorption in the rumen.

Apply fertiliser promptly after the first cut and evenly as possible. Be mindful of over-fertilising silage ground as excess nitrogen (N) and potassium (K) will have a negative effect on both crop preservation and animal performance. Too much nitrogen in grass at cutting reduces grass sugar levels & increases buffering capacity. To reduce this risk, allow enough time for any N applied to be taken up by the crop before deciding cutting date. Approximately 2 units of N per day are used up by the crop in good growing conditions. All second cut should also receive approximately 16-20units of sulphur.

Soil Index 1 2 3 4
P Required kg/ha 30 20 10 0
K Required kg/ha 70 50 35
N Required kg/ha 100

*Reduce N, P, K by 25:4:25 kg per ha on older swards with low growth potential.

Phosphorous & Potash Off-takes in Surplus Bales

harvesting bales

When harvesting surplus bales, be aware of the amount of P and K they remove from the paddock.

A typical bale of silage weighing 800kg fresh (200 kg Dry matter) contains 1.6 units of phosphorus (P) and 10 units of potash (K).

  • A 4-5 bales/acre crop will remove around 6-8 units of P/ac and 40-50 units of K/ac. This is important as a rough rule of thumb is that 50 units K/ac is enough to change a soil K index i.e., to go from index 2 to index 3 or vice versa.
  • If no slurry and only straight N was applied before and after cutting the surplus bales there will be a large shortage of P and K in this paddock. Farmers have found soil K indexes to be low on individual paddocks on the milking platform where a lot of surplus bales are removed, and K is not replenished.
  • A good rule of thumb to remember with surplus bales is that 3-4 bales per acre requires 1,000 gallons of thick slurry or 2,000 gallons of watery slurry to replace the P and K removed.
  • Where you have no P allowance, and no slurry is available to spread a compound like 29:0:15+S is a suitable option to replace nutrients taken off by the crop.

Preventing Lungworm Losses at Grass

The lungworm parasite can cause severe respiratory disease in grazing cattle, and result in losses in productivity from even mildly affected animals. Prevention and early intervention are key to reducing potential losses from lungworm.

Lungworm disease is usually seen from July onwards and depending on the weather conditions over the later grazing season, can persist into autumn and early winter.

Warm, wet weather, helps the parasite to disperse onto the pasture from dung pats, so periods of high temperatures followed by heavy rain can indicate a forthcoming high-risk period for susceptible cattle, as high numbers of larvae are suddenly released from the dung pats.

The problem for farmers, and vets, is that lungworm can be difficult to diagnose at an early stage and may not be spotted until a full-blown outbreak occurs. Lungworm is no longer just a disease of youngstock. There is an increasing trend for adult cattle to be affected too. Vigilance is therefore vital during the high-risk periods of the year.

What to look out for: Outbreaks of coughing in cattle should be investigated by a vet as soon as possible to allow early-intervention and minimise the long-term impact.

Other signs that can indicate lungworm infection include rapid loss of condition and sudden milk drop in lactating cows. After displaying initial signs of infection, we can confirm the presence of lungworm with faecal samples.

Treatment: Most wormers will treat lungworm burdens, however not every product will kill all life stages of the parasite. It is important that you speak to a vet before selecting a wormer so you can ensure you pick the most appropriate one. Young stock and growing cattle should be treated immediately with a wormer that quickly removes lungworm and prevents re-infection, to allow lungs to recover. All cattle in the group should be treated to ensure any sub-clinical cases are not missed. Overuse of wormers could limit exposure to the lungworm larvae to such an extent that resistance develops. A vet should assess severely affected individuals, as they may need additional treatment to treat pain, inflammation, and any secondary infection.

Grass & Grazing

This month’s feature farm is Donal McCarthy, Bishopsland, Drimoleague

Date 16/06/2021
Average farm cover (AFC) 533kg DM/ha
Cover/LU 133kg DM/ha
Growth 90kg DM/ha/day
Demand 60kg DM/ha/day
Stocking Rate 4.0 LU/ ha
Rotation 18 days
Yield (litres/cow) 23 litres
Fat% & Protein % 4.26% & 3.69%
Kgs Milk Solids / cow 1.88kgs
Supplement fed (kg/cow) 2.4kg

As of today (15/06/21) AFC is 535kg/DM/ha. This is after taking out a couple of paddocks yesterday as silage and brings the cover per cow down to 133.

Grass in front of the cows is improving in quality as most of the ground at this stage has been either cut for silage, pre mown or topped.

We were forced to graze some strong paddocks last week in an attempt to satisfy the cows as they were not content grazing very low dry matter grass. This hammered yield and protein. I do not expect milk yield to improve again but I hope solids will recover quickly. I am currently following cows with approx. 20 units of 27 2.5 5 + S.

Breeding: We are a little over 7 weeks into the breeding season. Since last week we are alternating 2 Friesian bulls’ day and night. I am also inseminating any cow I see in heat with an AA straw. There is a non-return rate of 75% at the moment.

Silage: Some of the first cut plus some surplus paddocks were cut on April 29th and we cut some surplus paddocks again on May 30th. Silage cut so far should be of fairly good quality and we had the added benefit of much needed after-grass over recent weeks.

At the moment, we are watching to harvest the remainder of the first cut, it’s poorer quality than I’d like but we couldn’t get to it any sooner.