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Dairy notes Oct 04

Managing October/November calving heifers

Many dairy herd replacement heifers will be calving down over the next few weeks. These are valuable animals and demand the best of care. Heifers should be examined closely in the last few months of pregnancy. Target body condition score at calving is 3.0 and growth rates should be limited to 0.50kg/heifer/day in the last two months of pregnancy.

This can be achieved by:

  • grazing bare pasture.
  • restricting silage intake.
  • feeding straw.
Heifers should be given dry cow minerals during the last 6-8 weeks before calving. Introduce them to the milking parlour 2-3 weeks prior to calving to get them used to the surroundings and avoid stress in early lactation.
Where building design is suitable, calved heifers can be batched as a separate group. This will reduce bullying from dominant cows in the herd and improve forage intakes.

Feeding wholemilk to calves

With the relatively good milk price at present, some milk producers are considering switching from feeding whole milk to calves. A range of products are available but the main differences lie in whether the powder is:
  • skim or whey based.
  • once or twice a day fed.
The final choice should be based on the quality of the ingredients, since a good start is essential in successfully rearing dairy heifers. All calves should receive colostrum within the first six hours to boost natural immunity. Whether reared on whole milk or substitute, calves should have access to water and good quality forage to aid rumen development.

Emptying slurry tanks before housing

Tanks should be emptied as soon as possible while there is still some growth and weather conditions are suitable. If slurry is spread during early October, and in suitable weather conditions, most of the phosphorous and potassium will be retained in the soil (being available for growth next year), although much of the nitrogen will be lost. Cattle slurry contains moderate levels of phosphate and relatively high levels of potash.
The best response, with least risk of pollution, will be achieved by:
  • spreading on soils which have low reserves of phosphorous and or potash (index 0 or 1, as indicated by soil analysis). Silage fields tend to be low in potash.
  • avoiding areas where there is a high risk of leaching or runoff. These include land liable to flooding or land which slopes steeply towards a watercourse.
  • avoid spreading within 10 metres of watercourses or 50 metres of a bore well.
  • applying moderate amounts of slurry – about 22,000 litres / Ha (2000 gallons / acre).
  • not spreading on wet ground, or if heavy rain is forecast within the next few days.

Bedding cubicles

A soft cubicle bed is essential to ensure that cows spend more time lying comfortably in the cubicles and also avoid injuries. For this reason most farmers have already installed mats or mattresses. These also reduce the level of bedding required by up to 75%. The bed must also be kept clean and dry to reduce mastitis and control cell count. Small amounts of lime, chopped straw, or sawdust are most commonly used.
It is particularly important to keep the bedding dry and replace regularly, otherwise mastitis causing bacteria will actually increase rather than decrease. Research carried out in America indicated that washed sand can be a better option, with less risk of bacterial build up, but can cause problems with slurry management systems.
Where mastitis or cell count are a particular problem, specially approved disinfectant materials can be applied to the cubicle bed once or twice weekly. Remember to keep passages clean in order to minimise fouling cubicle beds. Dung pats should be cleaned down from cubicles once or twice daily. Good ventilation whilst avoiding draughts, particularly on the cow’s udder, is also necessary.

When to harvest forage maize

Cob dry matter is key. Currently there is a lot of variation in cob development. Some crops are showing poor cob development, possibly as a result of weather problems at pollination. Other crops are developing normally, with the plastic mulch crops maturing faster than crops in open establishment.
Recent open days at UCD and Crossnacreevy show there is a gap in crop maturity between ROI and NI, therefore do not panic into early cutting. The target should be to harvest your crop at 30% total dry matter - anything less will sacrifice yield, feed quality and may lead to an effluent problem.
Northern Ireland crops under plastic are probably approaching 27% DM with open established crops around the 23% mark. Crops are currently increasing in DM by 2% each week – mostly starch production. It is therefore best to know your crop. The cobs make up the bulk of your crop yield, so cob dry matter is the key to harvest. Over the next two or three weeks, walk all maize fields extensively, sampling cobs throughout the field. The grains should take the impression of your nail, there should be no milk present and the starch should be ‘cheddar’ like. At this point the cob will be about 50% dry matter so contact your contractor and arrange for harvesting.
Why not carry out cob dry matter analysis in your kitchen range? Remove all the surrounding leaf, weigh the ear, cut these into smaller pieces and place in the ‘low oven’ overnight. In the morning weigh the dried material. When the weight is half of the original, the crop is ready to harvest. Remember, at harvest do not allow tractor and trailer wheels to soil the public highway.

Closing grazing

The first spring grazing rotation will be similar to the current one. Fields closed first now will have the earliest grass in the spring. These fields should be free draining. It is important to graze swards bare from now on, getting rid of the mat of dead grass at the base of the sward. The target residual grazing cover should be about 1,200 Kg DM per hectare. If you are reluctant to graze this tightly with milking cows, follow up with dry cows or young stock. Where milking cows are grazing heavy covers, grass utilisation can be improved by pre-mowing in dry weather. Areas where cows normally lie or areas heavily soiled during the grazing season will need to be ‘topped’ - preferentially with a disc mower.

Brucellosis - protect human health

Brucellosis is an infection caused by a bacterium. This organism is currently affecting cattle herds in many parts throughout Northern Ireland. People can become infected through contact with infected animals or animal products. Consequently, farmers are particularly at risk.
Follow the ten points below to prevent the risk of the disease:
  1. Keep to a minimum those who assist or are present at calving.
  2. Cover all cuts and abrasions with waterproof dressings – brucella enters the body through uncovered wounds.
  3. Wear protective gloves to cover hands, forearms and arms to ensure there is no skin contact with animal fluids, tissue, after-birth material etc. Wash gloves thoroughly before removal and remove gloves in such a way as to prevent the external surfaces of the gloves having contact with the skin.
  4. Wash hands, forearms and arms thoroughly AFTER work and BEFORE eating, drinking or smoking.
  5. Wear a visor if there is a risk of body fluids or tissue etc being splashed on your face, lips or eyes.
  6. Wear a PP3S respirator to prevent the organism being inhaled.
  7. Be aware of the early symptoms and seek medical advice if you have any concerns.
  8. Farm employees should immediately notify their employer if they have symptoms.
  9. Take all appropriate measures to ensure that you do not bring infection home to others on your clothing, boots etc.
  10. Do not drink raw, non-pasteurised milk.
But remember - preventing the infection getting into to your herd is the first line of defence.

Brucella Card

To help inform farmers of the possible health risks to both themselves and their families relating to brucellosis, the Health and Safety Executive for Northern Ireland (HSENI) has produced a Brucella Card and other material in a booklet form. These may be obtained from your local DARD Divisional Veterinary Office or from the HSENI.
DARD Farm Management Notes for October 2004 have been prepared by Greenmount Campus, College of Agriculture, Food and Rural Enterprise - Tel: 028 9442 6771. We acknowledge the contribution from Veterinary Service. For further information contact your local DARD Development Adviser.