Time to guard against costly nutritional deficits

Time to guard against costly nutritional deficits

A small investment in autumn feed testing can be good insurance against mineral deficiencies in dairy and beef cows that can lead to low growth rates and poor milk yields.

Winter feeds like fodder beet, low pasture phosphorus levels in some regions, and lower seasonal availability for copper can lead to deficiencies of both of these key minerals during late pregnancy, early lactation and calf growth.

Consultant nutritionist to SealesWinslow, Paul Sharp, says for around $100 a comprehensive pasture mineral test will provide the right information to farmers. Farmers can then work with animal nutritionists or vets to determine what supplementation will be needed to support stock. Liver biopsies from culled cows are also a useful indicator of animal reserves of key trace elements such as copper intake, and while blood tests can monitor trends, these are not as good at predicting animal stores.

“Copper availability to the animal is lower over winter and we often have low copper concentrations in pasture. Availability is further compromised by other minerals that could be in the animals’ diet – such as high iron content when grazing crops, high molybdenum levels in some soils, sulphur and zinc. These make the copper unavailable for absorption in the diet. Copper deficiency is most likely to occur in winter and early spring and it has impacts on conception and growth rates, and can even cause bone fractures in calves and osteoporosis in cows.”

Paul says zinc treatment for facial eczema can deplete copper reserves because zinc can lock out copper competing for absorption in the digestive tract. Fodder beet can also contribute to copper deficiencies, as well as increase the risk of phosphorus deficiency. Lactating cows need three to four grams of phosphorus per kilogram of dry matter, while copper requirements are around 150 mg/day for weaner calves and up to 450 mg for cows.

Although phosphorus fertilisers are used to boost pasture growth, observations by SealesWinslow over the past year show phosphorus deficits in pasture appear to be increasing, particularly in the South Island, possibly due to changes in pasture cultivars and grazing management, although the cause isn’t fully clear.

“The trouble with deficiencies of nutrients like phosphorus is that they can be hard to detect. If cows don’t get enough phosphorus, they start to mobilise their reserves, and can end up developing sub-clinical symptoms, including reduced appetite and rapid weight loss. This can lead to a reduction in milk yield in dairy cows. Some cows will recover from phosphorus deficiency, but others will go down – this is when you see creeper cows.”

The chance of phosphorus, magnesium, or trace element deficiency causing animal health issues can be reduced with supplements, including SealesWinslow’s molasses block range. This includes a Fodder Beet Block, which helps to fill the nutritional gaps of the crop. Low copper levels can also be addressed through molasses blocks, feed additives or dosing drinking water.

ENDS

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