PA065/A/07 DARD Farm Managment Notes March 2007

The Value of Early Grass

Running short of silage - is early turn-out an option?  Grass covers are building up rapidly on fields closed since last October/November.  With levels of 2700 -2800 kg dry-matter/ha on the best fields, the potential for early turnout exists on many farms.

Research at AFBI Hillsborough has shown that 2 hours grazing can reduce silage requirements by 25%, increase yield by up to 2.5 litres and raise milk protein by over 0.1%.  This will improve returns by £50 day in a 70cow herd – an important boost to income at current milk prices.

A slow transition to full time grazing over a 4-7 week period will allow cows to gradually adapt to a grass based diet, reducing the potential risk of the health and fertility problems normally associated with rapid turn-out.  

Turn the cows out for 2-3 hours/day as soon as possible.  It is essential to make the first rotation of the grazing area last until the third/fourth week of April when grass growth rates are fast enough to meet the herds demand from full-time grazing.  Restricting grazing time will ensure the first rotation is not completed too early.

Early grazing is possible, even on heavy land, provided access is good and the herd is encouraged to graze aggressively for the short period they are out:  

What fertiliser do you need to apply for first cut?  Under the recently introduced phosphate regulations, chemical fertilizers containing phosphate (e.g. 27.6.6 or 25.5.5) should not be applied to land unless there is a proven requirement – soil analysis is required.  On fields with high phosphate (P) and potash (K) indices of 2 or higher an application of over 1,7000 litres/ hectare (1,500 gallons/acre) of cattle slurry will meet the P & K requirements for a silage crop.  A straight nitrogen fertilizer can be used.

If the P index is one or lower, slurry will not provide all the P required and a compound fertiliser (27.6.6 or 25.5.5) could be used.  Where P index is 2 or above but K index is low (0 or 1) a zero P compound such as 27.0.6 should be used along with slurry.

Allowance should be made for the significant contribution to nitrogen supply from February/March applied slurry.  34,000 litres/hectare of cattle slurry will provide 25-30 kg of nitrogen/ha – a saving of about 2 bags of high nitrogen fertiliser/ha. (3,000 gallons/acre will provide 20-25 units N/acre – a saving of ¾ bag/acre).

With the possible exception of reseeds there is no yield benefit in applying more than 120kgs/ha (96 units/acre) of nitrogen for silage production.

If a silage field is to be grazed before closing for silage, make allowance for carry over of 50% of the nitrogen from urea applied in from February onwards.

Condition Score

Spring calving suckler cows should have a body condition score of 2.5 - 3.0 approaching calving. Cows with a body condition score higher than 3.0  should be separated out from the main herd and placed on a restricted diet.  

Thin cows in poor body condition should be fed ad lib silage of at least moderate quality. If the silage quality is below average supplementing with 1.0 to 1.5 kg meal per day in the final weeks prior to calving may be necessary.  

Pay particular attention to first time calvers, older cows, the best milkers and shy feeders as these are likely to be thinner than the other cows in the herd.

The calving environment

Good hygiene in the calving area will reduce the incidence of E. coli mastitis which is a major cause of cow deaths shortly after calving.  Thoroughly clean and disinfect calving pens before the main calving period starts.  

Assistance at calving

While careful supervision is necessary at calving, it is equally important not to intervene too early in the calving process.  

More problems are likely to arise where intervention occurs too early than where the cow is left for two or three hours after the calf’s feet appear.  Although the calving jack is a useful tool it should only be used by experienced operators and must never be used to exert undue pressure.

Always consult your veterinary surgeon if there is any doubt that calving is not progressing normally.

The value of silage?  

How much does it take to make one tonne of silage?  

The yield of silage can range from 30-45 tonnes/ha (12-18tonnes/ac) and this means that the cost of production can range from £11 to £16/tonne.

When an “opportunity cost” of using owned land or conacre prices ranging from £200-300/ha (£80-120/ac) is added, cost per tonne of silage increases by a further £5-£10/tonne.

How much should be paid for a tonne of silage?

Dry matter (DM), Metabolisable Energy (ME) and Crude protein (CP) content have a large effect on the feeding value of silage.  

Silages with differing analyses can be valued by comparing them to the feeding value and the current costs of barley (£135/t) and soya (£158/t).

The table below shows the relative value of poor, average and good silage.  This indicates that average silage (DM 24%, ME 10.6MJ/kgDM and C.P. 13%) below £31/t is better value for money than barley and soya with minerals.

It is impossible to put an accurate value on silage without having it analysed.

Value of poor, average and good silage relative to barley and soya.

Preparing For Turnout Of Cattle

Grazed grass is a much cheaper feed than conserved forage and this means that cattle should be turned out as soon as possible. Plan to turn cattle out to the driest fields. Lighter cattle should be turned out first and where possible separate into smaller groups over a larger area to keep stocking density low and reduce poaching.

Avoid waiting until there is a good build up of grass as the rate of growth at this stage will result in an oversupply of grass and subsequent reduction in grass quality in late spring and early summer.

Feeding The Lactating Ewe

For those ewes already lambed, high levels of quality feed are still required.

A ewe suckling twins has a very high energy requirement (approx. 3 times the maintenance level.) Meal feeding is not required if grass cover is at least 1800 kg DM /ha or approximately 5 cm for a dense sward. If grass supply is insufficient feed 1kg concentrate/day of a high quality energy and protein supplement to ewes suckling twins and 0.6kg concentrate/day to ewes suckling single lambs.

Worm Dosing

The ewes’ resistance to worms drops significantly around parturition with a rapid increase in the worm burden within the ewe. If this is not treated at this stage the ewe will heavily infect grazing pastures with worm eggs resulting in high levels of infection in lambs 6-8 weeks later. Ewes need to be dosed with an effective anthelmintic (with high efficacy against worm eggs) around lambing time. Consult with your veterinary surgeon on effective worm treatment.

Managing Early Grass For Sheep

New reseeds and swards high in perennial ryegrass are likely to give the best response to early nitrogen. Remember it takes grass to grow grass so avoid overgrazing of fields where possible, as this will have subsequent effect on future grass growth.

Silage areas can be incorporated into the early grazing areas and sheep should be grazed at 7 – 10 ewes/hectare depending on grass covers.

Do not overgraze swards as it will take them longer to recover.

Good planning should ensure that sufficient grazing areas are available and that sheep can be moved to allow fresh re-growth.

Drilling Spring Barley

The key determinant of spring barley yield is sowing date. One month’s delay in sowing often leads to a yield reduction of around 2 t/ha.

Sowing should take place as soon as a good seedbed can be created. The chosen seed rate, calculated from the thousand-grain weight, should lie between 350 and 400 grains per square metre. The lower rate should suffice for March-sown barley drilled into a good seedbed, however in poorer conditions, or if sowing later, the higher rate is preferable.

Winter Cereal Nitrogen Application

Normally one third of the total nitrogen (N) top dressing should be applied to all winter cereals during late tillering (late February/early March in winter barley, mid/late March in winter wheat). The remainder can then be applied during early stem extension, Growth Stage (GS) 30-32, which, for winter barley, is reached in early/mid April and by winter wheat in late April/early May.

Due to ideal sowing conditions in the autumn many winter cereal crops have established well producing crops with high plant numbers. Densely tillered wheat crops, (those with more than 1000 shoots/m²), are at increased risk of lodging later in the season and nitrogen top dressings should be delayed until after GS 30.

Crops at risk from take-all, for example second wheat’s on light land, may benefit from a little extra nitrogen at late tillering.

Is Sulphur Required?

Since 1985 atmospheric deposition of sulphur (S) has fallen by more than 25% in Northern Ireland.  Risk of deficiency is highest where soils are light and rainfall is low. Winter cereals should receive 20 kg S /ha (50 kg SO3 /ha) in the spring before GS 32. This is most conveniently applied as ammonium sulphate which will also add nitrogen.

Seed Preparation for Planting

Attention to detail during the handling and preparation of seed prior to planting can result in an increased early tuber yield, while optimising fry colour and skin quality.

Results from hot box testing at Greenmount of once grown home saved seed have shown that the skin blemishing diseases silver scurf and black scurf are prevalent. Seed should be treated with a fungicide pre-planting with the aim of reducing disease transmission and maximizing marketable yield.

Germination or sprouting ability of all seed lots has been good, indeed with the relatively mild winter conditions, management of sprout growth will be essential to ensure short, strong green sprouts are produced.

A number of systems are available for pre-sprouting including tray and bag systems. Systems must ensure adequate temperature control and ventilation (to control sprout growth and protect against frost) and light (to control sprout growth).

Seed of early potato varieties should be set up in sprouting boxes with the aim of promoting apical dominance i.e. producing one strong sprout per seed tuber, one stem and a small number of large tubers early. The opposite holds for maincrop potatoes where multiple sprouting is encouraged to produce many tubers which can increase in size over a longer growing season.

Maincrop seed potatoes should be set up to sprout 4-8 weeks prior to planting depending on variety and target market.

The aim in pre-sprouting late maincrop varieties such as Navan would be to accumulate 250-300 day degrees prior to planting. Working back from a target planting date of say 20 April, and allowing seven days for dormancy to break, seed set up on 1 March assuming an average daily temperature of 10^oC, would accumulate 264 day degrees, that is, 44 days x (10^oC - 4 ^oC).

Mini-chitting

This system of seed preparation aims to produce seed tubers with sprouts no more than 2 mm long. Seed is stored at 3-4 ^oC until close to planting time. The refrigeration unit is then turned off for 7-10 days to allow chitting to occur.

Once sprouts of 1-2 mm have formed evenly, the seed should be cooled down again to 3-4 ^oC to prevent further sprout growth up to planting. Mini-chitting, whilst not having the benefits of earlier harvesting associated with pre-sprouted seed, produces a crop that emerges quickly and evenly.

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