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Nutrition plays a pivotal role in preventing metabolic disorders post calving and through lactation. Metabolic disorders such as ketosis, fatty liver syndrome, hypocalcaemia etc can have a significant effect not only on a cow's lactation performance, but also fertility performance. These types of problems tend to be associated with higher yielding animals, however, all are controllable by good feeding practice, both in lactation and during the dry period.
Incorrect diets or feeding can lead to overly rapid fermentation in the rumen, which reduces the pH below the level at which the microbes are most active. This slows down forage digestion and reduces both feed intake and cud chewing which makes the problem worse by limiting the buffering effect of salivation.
Hypocalcaemia (Milk Fever)
The huge demand for calcium produced by the onset of milk production can cause blood calcium levels to drop sharply, precipitating milk fever either before or at calving. Even though cows can mobilise skeletal calcium, the process is slow and made worse by the demands of high yielding stock.
Hypomagnesaemia (Grass Staggers)
Cows only have a limited body reserve of magnesium and can only absorb a small proportion of the mineral in their diet, therefore grass staggers is easily precipitated by a fall in dietary magnesium. The risk is highest early in the grazing season given the lushness and low mineral content of spring grass, particularly if it is rich in nitrogen and potash. Similarly, later season grass in autumn can give rise to low mineral content.
Often charaterised by a pear drop like smell on the breath, ketosis commonly occurs as the result of a severe early lactation energy gap. The mobilization of large amounts of body fat in the liver, in an attempt to bridge the shortfall, can lead to toxic levels of ketones accumulating in the blood, milk and urine. This results in a loss of appetite and a marked fall in milk yield.
Factsheet 1 within feeding+ has more detailed information on metabolic disorders and how to address them.