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Dairy Notes September 04

SILAGE ANALYSIS

It is anticipated first cut silage will be better than the last two years with higher dry matter and feeding value.  Remember it has cost you money to grow, harvest and store, the silage and therefore it is important to get the feeding value from it.
To do so you must get your silage analysed.  Silage analysis gives an assessment of dry matter energy, protein content, and potential intake.
Your analysis results will allow you to select:-
  • The correct concentrate level to maximise milk from silage – a cow producing 35 litres of milk from silage and 9 kilos of concentrate is more economic than a cow producing 35 litres from silage and 11 kilos of concentrate.
  • The correct concentrate crude protein to balance demand – a cow in early lactation requires an overall crude protein in her diet of 17-18%.
  • The correct concentrate ingredients to maximise silage intake – high quality silage needs to be balanced with cereals, soya and by pass protein sources.

CONDITION SCORE LATE LACTATION COWS.

Cows calved before Christmas 2003 are over 250 days into their lactation and will probably be dry from the third week in October.  To have cows calving at condition score 3 it is important to assess their condition now! 
Take a critical look at fat cover over the loin, pelvis and tail areas.
  • Loin:-  There should be a slight depression along the cow’s top line and her loin. The shelf at the end of her transverse processes and her flank should be filling.
  • Pelvis:-  There should be a good cover developing on the plates.
  • Tail area:- There should be a good cover over the pin bones and the cavity at the tail head should be filling out.
These cows should be around the 2˝ condition score at the moment.  If you have cows that have not yet reached this condition and are in late lactation you will need to increase feed intake.  This can be grass or bale silage depending on availability or additional concentrates.

Grazing management

Good quality September grazing is a valuable asset to milk production. Swards should be grazed off at a cover of 3300-3500kg DM/ha - a sward height of 18-20cm (7-8 inches).  Clean aftergrass can be successfully grazed at a slightly heavier cover of 3800-4000kg DM/ha.
The exceptional growth during July and August has resulted in too much grass on many farms.  The recent wet weather has made it difficult to top or graze with other stock after the cows and grass quality is deteriorating.  It is essential that the build up of stemmy and rejected grass is cleaned out of the paddocks soon if a supply of suitable grass is to be built up for October and perhaps into November.  The options are topping, cutting for big bale silage, or tight grazing with other stock.  Failure to get the grazing into shape now could see disappointing milk yields from autumn grass. This would be a lost opportunity for cheap milk production.
With good growth conditions continuing, grass supplies need to be carefully and frequently monitored.  Your local Greenmount Campus Dairying Development Adviser can assist you to prepare a grazing budget.

MANAGEMENT OF THE COW AT CALVING

The period of time from drying-off until calving is a time of transition.  The management, nutrition, and health practices implemented during the transition period will impact on a cow’s productivity and profitability in the next lactation.
During the dry period the cow will rebuild her mammary tissue, replenish her body reserves, and condition her digestive system to achieve high intakes in early lactation.  However it is important to allow time for the rumen to adjust to the new diet fed after calving.  This is best achieved by introducing the silage component of the milking cow ration at 7 to 10 days before calving.  Concentrates can also be introduced at this stage but care needs to be taken not to induce udder oedema (excessive swelling).
This approach should help to maximise silage intake early into the lactation.  If intake in early lactation is inadequate, cows can lose too much condition as they ‘milk off their backs’, leading to health and fertility problems.  Milk quality, especially milk protein content, will be disappointing.
Freshly calved cows should be fed the best quality silage available in order to maximise intake and reduce the gap between energy supplied and that required for milk production.  If buildings allow, freshly calved cows should be grouped together for preferential treatment.
Monitoring body condition of freshly calved cows is a good indicator of energy levels.  Inspect these cows on a weekly basis.  If the majority of cows fall below a body condition score of 2.0 within six weeks of calving then steps need to be taken to increase energy intake including:
- increasing concentrate feeding in the parlour;
- introducing a midday feed;
- using alternative feeds if available, for example, potatoes, brewers’ grains etc.

Milk Fever Prevention

Milk fever is a nutritional disorder, which can be a particular problem with some, mainly high yielding cows calving in the autumn.  It is caused by low blood calcium levels, which frequently arise at the start of lactation.  The effect is caused by the natural flow of calcium from the blood to the udder and the failure of the body to maintain the optimum level for cow health.  It generally affects older cows.
While the effect is caused by low blood calcium, research work in recent years established also a link with low blood magnesium It was found that low blood magnesium predisposes cows to milk fever when calving down at grass.
The following management guidelines should be practised especially with cows known to be susceptible to milk fever.
  • Avoid lush grazing for the last three weeks of pregnancy
  • Supplement the diet with hay or straw or introduce buffer feeding silage before calving.  This will increase the bulk of roughage in the diet and therefore improve calcium absorption.
  • Feed a low calcium concentrate 2-3 weeks prior to calving and change to a dairy concentrate in the last few days before calving
  • Ensure adequate dietary magnesium and phosphorus intakes.
  • In consultation with your veterinary surgeon high-risk animals can be dosed with 25g calcium twice on the day of calving.
DARD Farm Management Notes for September 2004 have been prepared by Greenmount Campus, College of Agriculture, Food and Rural Enterprise - Tel: 028 9442 6771. For further information contact your local DARD Development Adviser.