• Dr. Aaron

Change

Change – hard at the beginning, messy in the middle, and gorgeous at the end. I came across this quote the other day and thought that it fit perfectly with the change that a dairy cow goes through during the transition from being a close-up cow resting and ruminating to a lactating cow producing 130 lbs or more of milk a day. Being a male, I have never experienced the birthing process firsthand. However, my wife has, and I think she would say that the birthing process is the hardest thing, physically, that she has ever done. I don’t think that we can expect the beginning of change to be any different for a cow.


However, for the dairy cow, the birthing process is only the beginning of change. From four days prior to this process to four days after this process, she doubles her energy needs, and at the same time her feed intake often dips; this sets her up perfectly to fall into a negative energy balance. She then begins to mobilize her body reserves of fat in the form of non-esterified fatty acids. Depending on the degree of fat mobilization, another energy substrate called ketone bodies may be produced. This change in energy demand and metabolism can have a negative effect on the body, modifying the insulin reaction and causing immune dysregulation.


Still, the challenges go on. In addition to a drastic change in energy needs, there is a huge change in calcium demands. A dry cow requires 21 grams of calcium a day whereas a cow that is producing 100 lbs of milk a day requires 74 grams of calcium. This is three times the amount that she is used to mobilizing and often leads to some degree of hypocalcemia. Sometimes this is manifested clinically as milk fever. However, more often (as much as 50% of the time) it results in subclinical hypocalcemia – a less than normal concentration of calcium in the blood that does not result in observed changes to the animal’s attitude. Like the effects of negative energy balance, subclinical hypocalcemia can have a negative effect on immune function. It also reduces smooth muscle contraction and feed intake.

As a result of all the changes going on during this transition period things can get a little messy here in the middle. We can see retained placentas, metritis, ketosis, DAs, and it seems like the list goes on and on. However, with proper management, we can limit the degree of messiness and have a beautiful end to the change. I think all dairy farmers can attest that there is something special about seeing a group of lactating cows chewing their cud as they walk to the parlor with full udders.

To get these girls set up for this beautiful end, attention needs to be given before this change starts. I think one could argue that getting them through this change could start even at birth or before. Certainly, we need to make sure that these girls get an adequate amount of high-quality colostrum as babies, and that they are managed to grow efficiently and reach an appropriate size and body condition when they calve.


When these heifers near the stage of parturition, it is important that a continued level of high-quality care is given to them. As with any stage of production, it is imperative that they are consistently fed an appropriate ration and that they are allowed adequate space to eat, drink, and rest. In addition, there is new research coming out that shows the value of heat abatement given to close-up cows and heifers. Not only does heat abatement improve the production of the heifer or cow, it also improves the productivity of the calf she is carrying.


These same recommendations – consistent ration, adequate space, heat abatement – should be followed for the fresh and lactating cows. In addition, I would add that limiting the time away from the pen and the time the cows spend locked-up is also critical. Lastly, as these cows go through the messy transition period, it is important that those that are struggling with the change are quickly identified and given appropriate treatment to help them progress swiftly to the beautiful end result.


This article appeared in Volume 13, Issue 2 of the Kansas Dairy Dispatch.

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