Transition & dry cow | Page 2 of 2

MANAGING THE UNSEEN IMPACT OF CALCIUM DEFICIENCY

All farmers will recognise a downer cow by the symptoms presented, and they know that this disease is brought about through a low level of calcium in the blood during a stress period.

This issue is commonly called milk fever and the cow involved a downer cow. What farmers won’t always recognise is that the cows that present with clinical symptoms are just a small part of a much bigger issue. This is why most researchers into the disease will use terminology such as hypocalcemia, as this broader term better conveys the true issue (calcium deficiency), and the fact that the disease takes many forms and effects many processes critical to early lactation.

For every incidence of a downer cow there will be many more cases where the cow stays on her feet but suffers the wider effects of the deficiency. Calcium deficiency can commonly exhibit in such things as calving problems, metritis, retained fetal membranes, mastitis, poor immunity, poor conception and the list goes on. Few of these things are as dramatic as the downer cow, yet they are equally important.

THE BODY’S CALCIUM BALANCING SYSTEM

The majority of feed sources supply more than adequate levels of calcium, yet calcium is among the most poorly absorbed elements. The body controls calcium uptake very tightly as an imbalance can lead to serious complications. This is done through the release of hormones, particularly, parathyroid hormone and vitamin D (a hormone not a vitamin), and calcium storage is controlled by another hormone called calcitonin. The body’s hormonal system responds quickly to manipulate the available calcium level based on demand. This system works really well, provided the diet is right and the cow has not been subject to longer term deficiencies. And also provided they are not under or over conditioned cows, as these cows are not as good metabolically at regulating these hormones.

MANAGING DCAD LEVELS IN NEW ZEALAND SPRINGER COWS

I recently wrote an article on the unseen impact of milk fever and how widely spread this issue can be without correct mineral support. The challenge of calcium deficiency is a fairly large topic and it’s important to now cover the other key information farmers should consider in managing the pasture dominant diets of our dairy herds at this critical time.

Pasture still makes up a significant portion of the diet for many of New Zealand’s springer cows. Our lush pasture and high growth levels lead to higher than optimal levels of potassium. Levels in the plant can often supply potassium in excess of 300% of a cow’s daily nutritional requirement. High potassium not only restricts the animal’s ability to uptake other essential minerals, it also changes the acid/alkali balance of the body which can seriously impact the body’s ability to release hormones critical to calcium utilisation during calving and early lactation.

The DCAD system of feeding involves adding acid forming salts to the diet of springer cows in an attempt to further drive this metabolic acid/alkali balance slightly more towards the acid range, thus facilitating the release of the hormones required to release calcium. Provided this feeding system is correctly implemented, when compared to other options, this approach is also very cost effective.

CALCIUM OR NO CALCIUM?

The calibration used in the correct formulation of these diets is expressed in total milliequivalents (mEq). An unmodified pasture-based springer cow diet can typically have a DCAD anywhere from +350 to +550 mEq’s or even higher, dependent on the level of pasture being fed. The aim is to get the mEq level of the diet down as low as possible. Under New Zealand conditions that normally means somewhere between -15 to +120 mEq’s. This is achieved by manipulating the feed sources in the diet and then adding a specific blend of acid forming salts. With the correct blend, palatability is maintained while reducing the total feed DCAD levels substantially.

TRANSITIONING WELL, DELIVERS RESULTS

Minerals and the Transition Period
The Transition cow mob, more commonly referred to by farmers as the springer cow mob, has the potential to respond to a higher level of thought and attention. Making key decisions around feeding and supplementation of this mob can have a bigger impact on a dairy farm’s profitability than any other single set of management decisions made throughout the rest of the season. A well transitioned cow will normally produce more total milk, have less disease issues, and a better reproductive outcome, than cows that don’t receive as much attention around this time.

Most experts agree that the transition period begins 21 days prior to the day the cow gives birth, into 21 days of lactation. For any cow this is a period of vast metabolic change. During this time their hormone levels are going through rapid developments as the body gets ready to mobilise many of the key minerals required, as well as preparing her body to mobilise the vast amounts of energy required during birth and lactation. Transition is normally the single highest stress period a cow will experience each year.

A TIME NOT TO DO THINGS BY HALVES

Both the period prior to calving and the period after calving are equally important to ensure the cow will produce at her potential, remain healthy and conceive again when mated. In my experience farmers will tend to either concentrate on the period leading up to calving or the period after – most commonly the period after calving gets most attention. And this can create a problem. In this article we will concentrate on the transitioning of cows only, rather than heifers (first calvers) where the focus need only be on ramping up the feed rate prior to calving. Transitioning cows is a very different process, a cow that is not transitioned correctly leading up to calving is a cow that will calve with her metabolic processes operating well short of full potential. She will be more exposed to both clinical and subclinical metabolic disease through either being calcium deficient or lacking the ability to mobilise sufficient calcium, ketosis, fatty liver disease, or possibly a combination of these problems.

DRYING OFF DAIRY COWS

With winter approaching you will no doubt be giving some thought to what date the cows should be dried off.

SETTING THE DATE:

Most of you will consider a number of factors when deciding on the exact date and approach used. Among things that will be considered will be, available feed, current cow condition, as well as expected calving spread. Some of you will choose to dry the whole herd off in one go, others will choose to dry off based on current condition, lighter cows first, heavier cows later, or if the calving dates are well spread, the decision may be based more around expected calving date.

DIFFERENT TECHNIQUES:

Many farmers may consider drying off their cows gradually by extending the time between milking’s, however expert opinion seems to favour, simply ceasing to milk the cow causing sudden dry off, as it is thought that this approach minimises risk of udder infection.

THINGS TO CONSIDER:

MANAGING THE UNSEEN IMPACT OF CALCIUM DEFICIENCY

MANAGING DCAD LEVELS IN NEW ZEALAND SPRINGER COWS

TRANSITIONING WELL, DELIVERS RESULTS

DRYING OFF DAIRY COWS

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