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Matt Ryan

Management Hints

March 2023

  • Seriously consider using sexed semen this year.
  • Because fertiliser will cost €1,130/ha, have a plan and be very conscious of costs.
  • Use protected urea all the time as it is best value for money.
  • Use the spring rotation planner to graze 30% and 60% of milking platform by March 1 and March 15, respectively.
  • Use the grassland planner to grow more grass and reduce silage costs.
  • Know and correct, now, the factors that lead to poor conception rates.
  • Weigh maiden heifers now and act!
  • It is vital to milk record at least four times this year.


According to Stephen Butler of Teagasc, Animal & Grassland Research and Innovation Centre, Moorepark, sexed semen is now a serious technology for the Irish dairy industry. Why? I summarise his ideas here:

    • The industry will have to generate fewer dairy male calves;
    • Better Economic Breeding Index (EBI) replacement heifers;
    • Better Dairy Beef Index (DBI) non-replacement calves;
    • Improved sustainability metrics.
  • If you have not used sexed semen before, try it on a small number of heifers, because sexed semen is a fragile product, and you must learn/know all the pitfalls associated with its use.
  • If you have used it in the past, with reasonably good experience, ‘go for it’ as there are over 200,000 straws available from all the good AI bulls. In trials, 25% of herds have conception rates as good as conventional AI; proving it can be done when all the advice is adhered to.
  • You must make a plan in order to achieve high conception rates. This should not be a ‘hit and miss’ approach as the straws are expensive and if badly done conception rates will be poor.
  • The plan: 
    • When to use? Within the first 10 days of breeding season but not later than the first three weeks.
    • Sex semen all maiden heifers:
      • They must be on weight target – weigh now to make sure; you will know if they are likely to ‘make it’ and, therefore, you can eliminate light ones from the plan.
      • They must be on second or third heat – therefore, if possible, record their heats from now.
      • Plan to fixed time AI (FTAI) them – this works well and has many advantages.
    • Sex semen suitable cows:
      • Identify your best cows.
      • Of these, identify cows: that did not have a difficult calving, ketosis, or acidosis; that withheld cleaning; that are lame or have other health issues. This info must be recorded to eliminate these cows from the plan.
      • They must be cows of one to four lactations with high fertility genetics.
    • Order sex semen straws now:
      • To help you, Stephen uses an example of 100-cow herd with 25 replacements (R2s), using the assumptions in Table 1 and with a desired calf crop of 30 heifers. These targets should also be used as your own targets. 

Table 1: Assumed (%) conception rates (CR) for conventional and sexed semen. Source: Stephen Butler.

  Heifer CR Cow CR
 Conventional AI  70%  60%
 Sexed semen (observed)  60%  50%
 Sexed semen (FTAI)  60%  50%
 % heifers/conception  90%  90%

 AI all heifers, once, with sexed semen. This will give you 13 heifer calves. Serve the repeats with beef AI to give you a total of eight to nine dairy-beef calves. From this you will be able to calculate how many cows you need to serve with sexed semen so as to have 30 dairy-heifer calves born. Therefore, you need 30 minus 13 = 17 female calves from the cows; and 38 sexed semen [17/(0.5x0.9)] straws will give you this. From this you will have 30 heifer calves and 71-72 beef calves.

      • From this you can see that you will require 2.1 to 2.2 sexed semen straws for every dairy replacement calf needed – in conventional AI it is approximately 5.5 straws.
      • I have a little programme that can help you calculate the number of straws required.
    • Contact your vet, make him/her aware of your synchronisation plans so they are ready to work with you.
    • Contact your AI person, who will be a major cog in the success of the sexed semen plan because correct AI timing is critical – 14-20 hours after the onset of heat, is a must! 

Next month, I will remind you of sexed semen issues to consider as you enter the AI season.


You should spend time deciding, based on price, soil test results, and your fertiliser plan which fertiliser or combinations best economically suits your own situation.

Table 2: Present (approx.) fertiliser costs and their unit value


Present (*) cost per tonne (€/t)

Cost per tonne unit (€/t)

Cost per kg (€/kg)

Cheaper  than CAN

CAN (27% N)





Urea (46% N)





ProUrea (46%)





(38.75% N)





16% Super (P)





50% Potash (K)





  • Table 2 gives the unit cost of N, P and K which will be used to establish the relative values of compounds in Table 3.
  • Table 2 shows that urea (46%) is 50% cheaper than CAN; while protected urea (46%) is 6% more expensive than urea. But it is 22.6% cheaper than CAN. With possible fertiliser costs per hectare of €1,130+, it may be hard to believe that 46% urea is €456/t cheaper than CAN equivalent, and that protected urea (46% N) is €236/t cheaper than CAN. Both are as effective as CAN as a source of N.
  • Table 3 shows:
    • That all compounds are cheaper than using a combination of CAN plus straight P and K as 16% Super and Muriate of Potash, respectively, by wide margins.
    • That 0:10:20 is approximately the same value as P and K as straights.
    • That 0:7:30 is €31/t cheaper than straight P and K.
    • That 10:10:20 at €945/t is cheaper than using the equivalent amount of 0:10:20 with urea (46%), protected urea (46%).
    • That 18:6:12 at €925 is cheaper than a combination of protected urea and 0:10:20 but more expensive by €45/t than a combination of ordinary urea and 0:10:20; the same is true for 14:7:14.
    • 27:2.5:5 at €920/t is more expensive than a combination of urea with 0:10:20. I guess the same would be true for 27:2.5:10 plus equivalent 0:7:30. But urea or protected urea and straights would be nearly €100/t and €50/t, respectively, cheaper.

Table 4: Cost of 50kg N application, using different fertiliser types.



Protected urea


Kg N spread




Cost per kg N




Total cost of application




*Needed to supply the same plant available N.

  • Table 4 highlights the cost of applying 50kg N/ha, taking into account the present cost of the three nitrogen sources and the efficiency of each.
    • Protected urea is more efficient because of lower nutrient losses compared with urea.
    • The value of retaining N, due to urease inhibitor in protected urea, that previously lost as ammonia has increased dramatically in line with the increased fertiliser cost.
    • Therefore, use protected urea all through the year and you can reduce greenhouse gas emissions by 7-8% on your farm, while at the same time saving yourself money and growing as much and more grass (based on a seven-year trial in Johnstown Castle). 
  • Nitrogen: It is recommended to have 23 units N/acre applied in February. With that applied you should apply 2.5 bags 18:6:12 in early March, that is 45 units N and, if no P or K has been applied to Index 3 soils, 15 units P and 30 units K.
    • If P and K are Index 1 & 2, then use four bags 10:10:20 over a few months.
    • Silage fields must get four to five bags 0:7:30 and protected urea – slurry is very suitable and can be used to reduce the amount of bag manure.
  • Slurry of 7% DM contains 10, 6 and 36 units of N, P and K, respectively, per 1,000 gallons – where it is being used, discount bag fertiliser need as outlined in previous bullet point. 
  • Manage fields with clover as per all other fields.


  • Being a key performance indicator, we must plan 14-16t DM grass/ha and maximise the size of the first cut to reduce silage-making costs, particularly contractor charges, and save on N by only requiring a small second cut.
  • You haven’t a chance of achieving it unless all fields on farm have a pH of 6.3+, and all are Index 3-4s for P and K – no more talk on that – just do it! Reseeding, also, is a big help.
  • You must make a grassland plan for the year, NOW, so that the acreage you have is adequate to provide grazing and silage for all livestock being kept. I have an Excel programme for that but it works as follows by providing the following grazing hectares:
    • April-May: 4.7-4.9 cows/ha, 2,500kg (cattle weight)/ha, and 23 calves/ha;
    • June-July: 3.6-3.9 cows/ha, 2,200kg/ha (cattle weight), 14 calves/ha;
    • Aug-Sept: 2.7-2.9 cows/ha, 1,700kg/ha (cattle weight); seven calves/ha;
  • Once these areas have been allocated, the remaining area of the farm must be cut for a heavy silage cut. With the nitrate restrictions, you have no chance of having enough silage unless you close large areas of the farm for first cut and take heavy cuts. 
  • You will know I am not in favour of a grazing system that involves taking out surplus bales – only rarely when we have massive growth.
  • From this plan, you know the area being grazed by the cows from April to October and this will be managed using the grass wedge.
    • The pre grazing cover (PGC) for a stocking rate of 4.7/ha and a 21-day rotation for a 550kg cow producing 2kg MS/cow (means 17kg DM/cow of a daily requirement) is calculated as follows: 4.7x17x21 + 50 = 1,730kg DM with an average farm cover of 800kg DM/ha (50 = post grazing height of 50cm).
  • In my experience, to be able to graze cows at 4.7+ per hectare from April 15-20, one needs to have an average farm cover of over 650kg/ha in early April. This is only achieved by:
    • Having the specified % areas grazed up to March 1 and March 15;
    • Having adequate levels of N applied in time; and
    • By feeding the required levels of meal as directed by a grass budget.


Because non-return rate (NRR) or conception rate (%) to first service is poor on many farms – look up yours on the ICBF fertility report for 2022 – Stephen Butler, from Teagasc Moorepark addressed this on a recent Zoom session with my clients. The following is his summary of the factors to address:

    • Age:
      • Young cows are more fertile than old cows.
      • Examine the age structure of your herd.
      • Examine the age structure of the cows culled because they were not in-calf.
    • Days in milk:
      • This is the most important factor affecting herd fertility.
      • The more days in milk prior to mating the better is conception, because the uterus has more time to recover.
      • Conception to first heat after calving is lower by 8%. 
    • Body condition score (BCS) at AI:
      • Influenced by BCS at calving and post calving nutrition.
      • Thin cows at calving take longer to come back in heat.
      • And are more likely to be bred at first heat.
      • If lower than 2.75, submission and conception rates at six weeks can be reduced by up to 16 per cent.
    • BCS loss from calving to mating start date (MSD):
      • Cows that have high BCSs at calving will lose a lot of weight to MSD.
      • If BCS loss is greater than 0.5 units submission rates can be reduced by up to 49% and pregnancy rates by up to 20%.
    • Post-calving metabolic and reproductive disorders:
      • Milk fever, ketosis, and displaced abomasum.
      • Retained placenta, metritis, endometritis.
    • Mastitis and high somatic cell count (SCC):
      • Before and after service.
      • Local inflammation in mammary gland.
      • Has a systemic effect on the whole animal.
      • Detrimental to the control of reproduction.
    • Dietary deficiencies:
      • Energy intake, either two weeks before or after AI service.
      • Phosphorous, copper, celenium or iodine deficiency.
    • Disease prevalence within the herd:
    • Lameness is a major issue;
    • Respiratory diseases;
    • Parasite burden.
    • Vaccination strategy:
      • Complete all vaccination programmes at least one month before MSD.
      • Live vaccines can cause corpus luteum regression.
    • Milk production:
      • Normally, this is not a problem if cows are well fed, maintaining or gaining BCS.
      • However, if they are milking far higher than their milk and fertility genetic sub-indices, it then may be an issue.
      • But periods of under-nutrition or rapid changes in diet will affect it.
    • Individual performing AI:
      • Is it a technician or DIY? Initial the animals by name of server.
      • DIY operators need a refresher course – admit if you are not up to standard or have too much work to do.
      • DIY operators must have straws stored correctly, and manage them correctly before and during the AI process.
      • How many services per man at any one time? With synchronisation, AI operators are under so much pressure that there is always need for extra technicians on the day.
    • Bull to bull variation:
      • Use a large team of bulls and no bull should be used on more than 15% of herd matings.
      • Based on discussion group member comparisons, some individual bulls gave bad results last year.
    • On-the-day management of cows:
      • Avoid having cows stressed by being bullied, or short of water or feed.
    • Optimum time to AI:
      • For conventional straws it is 12-24 hours after the onset of heat.
      • And for sexed semen it is 14-20 hours after the onset of heat.
      • Re-serving cows the day after service, according to Dr Doreen Corridan of Munster Bovine, can have a detrimental effect on conception rates.
      • From this, it is obvious that good records are essential when analysing poor on-farm fertility.



  • Feed magnesium to milkers at grass if on low levels of meals. They need 2-3oz/cow/day.
  • Continue dry-cow minerals to March/April, calves.
  • Condition score the whole herd now. Cows that are a BCS of 2.75 or less should be put on once-a-day (OAD) milking, but continue to feed well.
  • A let-out worm dose is not necessary for these animals (or any other yearlings). But if fluke – liver or rumen – is a problem (check dung sample) dose before let-out.
    • Bits and pieces for March
    • The chances that meal feeding should now increase as cows’ individual intake demands are higher and we need to ration grass in cows’ diet (adds an extra €2.80/cow/day profit) so that the first rotation lasts until early April. Feed 3-5kg/cow/day.
  • Stock them on grass at 2,500kg/ha, or seven to nine per hectare until July:
    • Equally, a copper bolus may be required if copper deficiency is a problem on your farm.
    • Also, address iodine where necessary.
  • Vaccinate for BVD, IBR and leptospirosis now or over next two weeks (do the cows also):
    • This is a ‘must-do job’ for most herds. 
    • It must be done three to four weeks (at least) before MSD.
  • ‘Small’ bulling heifers are the issue and they represent the potential of your herd to expand next year or give you an extra cash income of €1,500+ each. Therefore, consider your options with them:
    • A ‘small’ yearling heifer is one weighing less than 240kg on March 1.
    • There are 60 days to May 1, which is an appropriate MSD.
    • With good grass they will put on 1kg/hd/day of live weight gain.
    • With good grass and 1-2kg meal for some of the time they will do 1.25kg/day.
    • They may be still a little light, so it is suggested you delay their bulling date for 15-20 days, and serve with a Jersey, which, even though not totally advisable, represents a far better option than carrying them over for another year.
  • Let out big yearlings’ heifers (290+ kg) onto grass immediately:
    • They will lose weight for four to six weeks (gut-fill) after let out.
    • They will be well conditioned into the grass environment by the time the breeding season starts.
  • Manage animals accordingly to achieve these objectives.
  • Conception rates will be best if:
    • They weigh 310-340kg at MSD.
    • They are on the third heat on service day.
    • They are well used to a grass diet at that time (let them out early March).
    • No injections within one month MSD.
    • Adequate cover for minerals, particularly iodine.
  • To produce enough heifers from your own herd you must:
    • Calve down 30% of herd to heifer calves. No more, because they are too expensive to rear and farmers are not prepared to pay the €2,000 one needs to achieve as two-year-olds so as to make a small profit.
    • Also, there is no point in being overstocked with non-profitable animals.
  • The following problems arise with bulling heifers (R2s) on dairy farms:
    • Most of them are not big enough at calving, due to being too small at mating.
    • Some are too fat and heavy – bulling heifer over 360kg will have trouble going in-calf and will remain in milking herd for shorter periods.
    • We have too few AI-bred heifers with very high EBIs with high % fat and protein available. 
    • They are not at grass long enough pre-mating because they will lose weight for six weeks after going to grass if they have done ‘too well’ on silage.
    • Iodine and copper are two key minerals to promote ‘heat’ and good conception rates – if grass is deficient in those, you are in trouble because, unlike cows, they will be on no meals.
  • Bulling heifers must now weigh 53% of their mature weight:
    • That is 295kg for a Friesian and 285kg for a Jersey cross on March 1.
    • If underweight, feed 1-2kg meal to light ones while on grass from now until May 1.
  • Calf snippets:
    • Feed milk replacer (not cow’s milk) to replacement heifer calves to prevent the spread of Johne’s disease at 6L/day. With the price of milk this year we should feed all milk replacer.
    • Let out suck calves to grass in early March as they will thrive as good as indoor-reared calves, have less disease, and you will have less work:
    • Give them a fresh area of grass every four to six days.
    • Provide straw in a rack at all times.
    • Feed 1kg meals/calf/day but protect against bird contamination (coccidiosis).
    • Before selling male calves, check their EBI – it may be very high and they could be valuable.
  • Use the spring rotation planner to guide your rationing of grass to cows so that you have enough so as to delay the second rotation start date to early April.
    • On dry land, aim to have 30%+ and 60%+ grazed by March 1 and March 15, respectively.
    • On wet or ‘late’ farms, these dates will be delayed by seven to 14 days.
  • Milk recording is a must-do now as there is much more you can do in terms of cow selection for mating or culling.
  • Farm roadways, particularly damaged ones, must be resurfaced to prevent lameness – serious consequences to BCS and peak milk yield at this time of year.
  • Start researching the AI bull catalogues/Active Bull list for the best and most suitable AI bulls for your farm and cows.
  • Spread 2t lime per acre now but:
    • Avoid using urea for three to six months afterwards.
    • Avoid using slurry for three to six months afterwards.
    • However, you can spread lime seven days after spreading urea and slurry.
    • There is no issue with CAN/lime inter-reacting.
    • Leave seven days between spreading lime and slurry, CAN or N, P, K compounds and vice-versa.
    • “Develop an approach to maximise income at the top end of a business cycle and do not feel the slightest bit embarrassed about it!”.

Padraig Walshe (RIP)

My sympathies to Ella, Julieanne, Catherine, Elma and Pat on the untimely passing of Padraig. He was a great friend, confidant, and inspiration to all of us who knew him. His significant contributions to national agriculture have been well documented, but I got to know him from the initial formation of the Damer Discussion Group, formed in 1989. Being a very good farmer, Padraig was an early adopter of all dairy research technology, which resulted in him growing 18-20t of grass and with a herd EBI of €222. He helped and shared all the information he had, unstintingly, with all his contacts. He will be sadly missed. May he rest in peace.