regie alimentairev min



Solutions to prevent the risk of metabolic diseases such as clinical hypocalcemia and subclinical hypocalcemia, which can greatly influence the success of calving.

In recent years, the impacts of clinical hypocalcemia and subclinical hypocalcemia on the performance of dairy herds have been better understood by the various stakeholders involved in milk production. In North American dairy herds, the incidence of clinical hypocalcemia, more commonly known as milk fever, is up to 7 percent.
Having rather characteristic symptoms, it is rather easy for the producers to detect it.

For its part, subclinical hypocalcemia is present in over 50 percent of cases after calving and its impact is much more insidious because symptoms associated there are far less visual. Placental retentions, metritis, displacements of abomasum, milk production losses are among other issues related to hypocalcemia and have a significant financial impact on the company.
As a producer or nutritionist, various strategies to limit this problem are at your disposal. Working with high or low intakes of dietary calcium is one of those possibilities. Also, minimizing potassium intake often helps to reduce problems with calving.However, it is not necessarily possible to apply these strategies to all producers and they do not always work effectively in subclinical hypocalcemia. It is therefore important to have several solutions in its toolbox to deal with any eventuality.
The use of negative dietary cation-anion difference (DACA) in calving preparation is the most recognized strategy of the dairy industry to maximize the release of bone calcium through a more active parathyroid hormone (PTH) in early lactation that makes the cow as independent as possible when the demand for calcium increases.

Providing an anionic ration to cows in preparation for calving thus makes it possible to limit the development of metabolic diseases, to maximize consumption and to obtain optimal milk production. To do this, the use of an appetizing anionic source is recommended to maximize consumption during this critical period.Depending on the anion dosage, this feeding strategy may be partially or fully acidified. As a result, the more acidified the ration, the more active the PTH, and the higher the serum calcium (amount of calcium in the blood) in the hours following calving. Obviously, a fully acidified program is to be favored when the management allows it. Since everything is done in the weeks leading up to calving, having validation tools is more than essential to ensure a successful lactation. In a quick and easy way, this dietary strategy can be verified through urinary pH, before calving. Thus, it is possible to react quickly and stay in control if a readjustment of the anion dosage is necessary. Secondly, it is still possible to validate the effectiveness of the program by determining serum calcium 48 hours after calving. The objective to achieve when working with a fully acidified program is a urine pH ranging from 5.5 to 6.0. However, several factors other than the dosage of anions influence the effectiveness of the program. To ensure success in calving, having control over what cows consume is a priority. Different parameters must therefore be validated to maximize the success of the program and here are some not to forget:


1. Mineral analysis of water

The impact of water consumption during lactation is well known to all because the demand for this food is important given the milk production. However, water consumption at dry period and in preparation for calving may vary from one individual to another. Thus, water with a rather basic pH or having a cation content such as sodium or calcium may play a role in the efficiency of the food program. Without necessarily recommending a treatment in the drinking water, it may be relevant to consider the mineral analysis of water in the dosage of anions, especially if the results do not fully reflect what was planned initially.


2. Moisture of the ration

All factors affecting sorting will certainly have a significant impact on the effectiveness of the program. For starters, too dry a ration will limit the adhesion of anions to silage particles. Thus, it is possible that the anions are unfortunately swept at the end of the day when the manger is cleaned. This obviously causes economic losses
in addition to a food program that is definitely inefficient. To avoid such a situation, a dry matter of 45 to 50 percent is targeted.


3. Particle length

The cutting length of the various fodders greatly influences the sorting of the ration. In an ideal world, we try to have cutting lengths as uniform as possible. Thus, the cow will not be able to select the food that attracts the most and, therefore, the consumption of anions will be more uniform.


4. Presence of a round bale or dry hay at will

The presence of dry hay at will or accessibility to a round bale, in addition to a basic ration, can influence the effectiveness of the program, because this type of control limits the control we have on the consumption of cows. Thus, those who appreciate less the taste of anions will most likely consume more dry hay or round bale and thus the actual DACA of their ration consumed will probably be far from that calculated by the food program.
However, this situation represents the reality of many dairy producers. Depending on the objectives of the producer, it is sufficient to validate the best approach according to the current management.


5. Homogeneity of the mixture

It is well known that there is sometimes a difference between the ration on paper and what cows actually consume. However, this variation should not be excessive and may be due to human or mechanical error in the amounts of ingredients added to the mixer. However, this variation can also be due to a lack of homogeneity of the mixture. This lack of homogeneity may, in turn, be caused by multiple factors such as a poor order of incorporation of ingredients into the mixer or poor mixing time.
Also, mixing a small amount of ingredients in a large mixer can cause such a problem. This is often seen in smaller herds with smaller groups of cows preparing for calving. It may therefore be relevant to validate this aspect.


6. Animal density too high

A park containing too many animals will result in a variation in consumption from one individual to another, as competition at the feeder may be increased. By the same token, if the consumption is variable, the results will vary just as much. This aspect is important, regardless of the food strategy chosen.

Of course, not all factors have been addressed here. In addition, some are more applicable to tie-stall and some to loose housing. However, these key factors will allow you to ask yourself the right questions and validate some management issues that will be as beneficial in lactation as in preparation for calving. With a significant financial impact, hypocalcemia is a problem that deserves attention. The current dairy production environment is making producers more efficient and effective. Emphasis on calving preparation is one of the ways to achieve this goal.

Gabrielle L. Dumas, agr., DCL nutrition + animal health

Scroll to Top