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Securing dairy cows during grazing in spring

Grazing in the spring often can lead to a loss of production in dairy cows. Grass tetany may be the cause. The disease causes a decrease in appetite, milk production and milk fat content. The cause: a lack of magnesium, often associated with a drop in ruminal pH.

In the pasture: beware of grass tetany

In spring, young grass in pasture is rich in soluble nitrogen and fermentable carbohydrates, low in cellulose, and the magnesium to potassium ratio (Mg2+/K+) is low. As a result, the intra-ruminal absorption of magnesium decreases. This leads to grass tetany. The disease presents a high risk for dairy cows during the first two months of lactation. Animals come out of a long period in the shed and could have experienced weight loss after calving.

Several stress factors combine:

Low ingestion and low temperatures can trigger a large adrenaline rush. This leads to a rapid fat mobilisation with a sudden mobilization of energy reserves, and a decrease in the concentration of magnesium in blood plasma, causing grass tetany. This disease is characterized by neuromuscular and digestive disorders, accompanied by a decrease in intake and milk production. In the most severe cases, the animal may die.

 

Securing the ruminal pH

During the grazing period, the presence of fermentable carbohydrates, combined with a low proportion of cellulose in the young grass ingested, leads to a high production of volatile fatty acids in the rumen. Their accumulation causes a drop in rumen pH, which can lead to sub-acute rumen acidosis. Namely a pH < 5.8 for more than 3 hours. This low pH causes a decrease in feed intake, milk production and milk fat content. The cost of production therefore increases. The economic loss is estimated, on average, at 1 euro per cow per day (Plaizier et al., 2008).

Studies show the positive effect of pHix-up

To reduce the risk, ruminants need an increased intake of rumen-soluble magnesium. The magnesium present in pHix-up, at 48.5%, is highly soluble. The product is a good source of Mg2+ for ruminants during the risk period of grass tetany. With an acid neutralization capacity of 39.0 meq/g, pHix-up is perfectly suited for rapid and sustained acid neutralisation. The 97% persistence of the product’s effect after 6 hours in vitro provides complete protection for your dairy cows.

The positive effect of pHix-up on ruminal pH has been demonstrated in tests involving more than 10,000 dairy cows worldwide. Milk and total fat production also increases with pHix-up. On average, ECM (Energy Corrected Milk) and total fat were increased by 1.2 kg and 50 g per cow per day (p < 0.001).

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