Determining trace element deficiencies:
Consult your veterinarian for advice on trace elements. Although blood test is the most accurate method of determining deficiencies, mineral imbalances are hard to diagnose, even with blood tests.
The horse’s metabolism will try to keep the blood level of minerals at normal levels even when there is insufficient for normal bone growth. It is best to prevent problems by providing a good balance in the pasture.
Care needs to be taken with lush pastures because some horses, particularly ponies, are prone to founder (laminitis) when the feed is lush. Urgent veterinary attention must be sought for any horse that shows a reluctance to move which might be the first stages of founder.
Grazing management:
Horses are wasteful grazers. They selectively graze pastures, damaging parts of the pasture by overgrazing and leaving other parts of the pasture tall and rank and relatively unacceptable. Management practices should reduce wastage of feed.
At all times maintain a high level of ground cover to prevent erosion. The appropriate level will vary with the situation (soil type, rainfall, slope, etc.) For most high rainfall areas of New South Wales 90% ground cover is acceptable.
Allow horses to graze the pasture. After they have grazed the paddock to 2.5 cm in height over 20 percent of the paddock, remove the horses. Slash or mulch the paddock and harrow the manure. Wait until the pasture is 10 cm in height before regrazing.
Opinions differ on the management of manure droppings in horse pastures. Spreading manure droppings evenly by running a chain harrow will add fertility to the soil and spread any parasite eggs in the droppings where they can be killed more easily by sunlight.
Collecting and removing manure will help grazing management but could lead to major nutrient deficiencies. It is critical to apply a balanced fertiliser program with potassium if all the manure is removed. The other alternative of leaving the manure in the paddock encourages selective grazing.
Rotational grazing is a must for horses. It is desirable to have at least 3 paddocks for a group of horses. However, because horses have a pecking order that includes biting and kicking, many horse managers prefer to set stock paddocks with smaller numbers of horses which means that paddocks do not get a rest to recuperate.
The rotation of clean pastures, in conjunction with a good parasite control program, will help to discourage parasites and diseases. Keep horses out of the pasture during extreme wet weather to prevent ‘pugging’ of the soil with hooves.
Most pasture species will benefit from spelling – some to set seed and others to replenish energy reserves. The optimum time to graze ryegrass is at the three leaf stage, prairie grass at the five-leaf stage and kikuyu at the four and a half leaf stage. To encourage vigorous growth of pastures it may be necessary to topdress with nitrogen fertilisers such as urea and nitram. Apply these fertilisers straight after mulching or slashing and give the paddock at least 4 weeks to regrow before grazing.
Weed management:
Weeds are a problem in horse pastures because of selective grazing by horses and also because horses are usually supplementary fed. The bought feed can contain weed seeds. Correct grazing management is critical in controlling weeds but particular weeds can cause problems.
- Annual and perennial broadleaf weeds like Paterson’s curse, Paddy’s lucerne, wild radish and nettles thrive in horse paddocks. They grow in the overgrazed areas of the paddock. Spraying with a registered herbicide or removing by hand is necessary. These weeds usually grow near fence lines and under trees.
- Advanced hepatic disease has been noted in horses grazing Paterson’s curse (Echium plantagineurn) and Fireweed (Senecio madagascariensis) in New South Wales.
- Horses have the ability to spread weed seeds. Paddy’s lucerne (Sida sp.) has improved seed germination after passing through the digestive tract of a horse. St. John-Sweeting and Morris (1990) suggested horses that have previously grazed weeds should be held and fed in yards or stables for 10 days before being introduced to weed-free pastures.
- Crofton weed is very poisonous to horses. It thrives on coastal hill country with high rainfall, preferring sandstone and rocky escarpments. Inspect all horse pastures for this weed.
- Catsear or flatweed (Hypocboeris radicata) causes stringhalt in horses. It is often confused with annual smooth catsear (Hypochoeris glabra) and dandelion (Taraxacum officinale). Do not graze horses in heavily infested fields during the summer–autumn growth period.
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