Lush grass is far higher in energy than the cow requires and will lead to weight gain. Deposition of excess fat increases the risk of calving difficulties. Tight stocking can limit intakes but increases contamination and poaching of the ground. Hygiene for calving may be compromised. The cows will also have periods with limited intakes unless low energy forage is provided in feeders. Providing lower quality grazing is preferable. Poor pasture, conservation grazing or fields where growth has got ahead with higher levels of seed heads are all lower in energy than lush regrowth.
In wet conditions on lush pasture the risk of grass staggers is high. Where potash or slurry has been included in the fertilising regime these risks are greater. If possible use unfertilised grazing or avoid potash in the calving paddocks. Providing higher fibre, lower energy grazing will slow the rate of digestion and offset some of the risks of low magnesium. Supplementation should be provided either by buckets or in the water source if the trough is the only water supply.
The risks of milk fever are not often considered for suckler cows but there may be a role of subclinical milk fever in slow calvings. High potash, lush grazing presents a milk fever risk and should be avoided if possible. If lower potash grazing is not available the risks of milk fever can also be offset with increased magnesium supplementation.
After calving providing the highest quality grazing available is essential for milk yields and recovery for breeding. The risks of grass staggers remain however and continued magnesium supplementation is necessary, particularly in periods of cold, wet weather when dry matter intakes are depressed.
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