Management practices, such as nutrition, cow comfort and hygiene, are crucial to addressing metabolic issues
Metabolic disorders are extremely costly to dairy farmers. Twenty five percent of animals that leave the herd do so within the first 65 days into lactation, often as a result of one or more metabolic issue. Most occur around calving and are often the result of issues with management relating to nutrition, as well as cow comfort, during the dry and transition period.
Metabolic problems do not stand alone and usually occur together. It is often difficult to put an accurate cost on individual disorders, but what is clear is that the overall cost is certainly greater than the direct loss of income from reduced milk production.
Negative impacts on health and fertility create issues with longevity, which further compounds the effect on bottom line. Common metabolic disorders include ketosis, hepatic lipidosis (fatty liver), hypocalcemia, retained placenta (RP), displaced abomasum (DA) and laminitis.
This article looks at the role proper nutrition and management can play in preventing and treating these costly conditions in dairy cows.
The cost of post-calving metabolic disorders can be significant when one considers treatment costs; labor costs associated with treating the animal; and the subsequent loss in milk production and reproductive efficiency that can occur.
Metabolic disorders poses costly challenges for dairy farmers. Beyond losses in milk production, the residual losses add up, i.e. deaths, open days, etc,. Many of these issues can be prevented through proper post-calving nutrition. | C Guard, Cornell University (1998)
Coupled with that is the issue that most of these disorders do not “stand alone” — the occurrence of one tends to increase the risk of another. Additionally, subsequent problems may mask both the original and further problems, which compounds the overall economic impact.
The cost to producers of subclinical hypocalcemia, for example, can actually be much greater than that of the clinical disease. While the cost per case may be higher for the latter, the vastly greater number of affected cows — coupled with the effects on other aspects of metabolism — makes the cost of subclinical hypocalcemia potentially four times greater than that of clinical milk fever.
Although the ultimate goal is to have zero incidences of metabolic disorders, various practical target incidences exist for most of them.
For ketosis, milk fever and DA, most target values are less than 5 percent. Suggestions for RP and lameness appear to be from less than 5 to 10 percent. Taking these into account, reducing milk fever incidence from 8 percent to 5 percent in a 200-cow herd would represent a potential saving of $1,086.
Add this to the potential further losses through increased risk of other metabolic disorders, such as ketosis and DA.
Reducing the risk
Risk of occurrence of all of the aforementioned disorders can be significantly reduced by appropriate management, particularly during the dry and transition periods — as well as correct youngstock management.
Nutrition is probably the most influential and most often considered when looking at management practices to address metabolic issues but cow comfort and hygiene are also crucial. Genetics obviously plays a role with regard to susceptibility and selection of bulls and breeding lines can go some way to helping reduce the risk further.
Minimizing the incidence of metabolic diseases and, therefore, impact on efficiency of the herd should be a holistic approach combining management, the environment and nutrition. However, many of the individual strategies focus on nutrition during the transition period.
The importance of a balanced ration at any stage of production is well-accepted, but there are specific practices that can contribute to metabolic health.
Most prevention strategies are concerned with manipulation of the close-up diet.
For example, dietary calcium (Ca) and potassium (K) restriction in the close-up dry period can be used to help prevent hypocalcemia. Feeding diets very low in calcium and avoiding forages high in Ca and K (for example, lucerne) is a traditional practice. Materials, such as zeolite, will bind Ca and prevent absorption, thus effectively mimicking a low Ca diet. However, it may be difficult to formulate low Ca and K diets, and the animal still requires a certain level of dietary calcium.
Dietary cation-anion difference (DCAD) can be very effective provided close-up and far-off cows can be managed separately. However, animals on DCAD diets should be closely monitored via urine pH. Dosing with vitamin D3 for a short period of time prior to calving has had mixed results. Individual minerals can also impact disorders, such as selenium and retained placenta.
Monitor body condition
Minimizing negative energy balance (NEB) immediately post-calving will help reduce problems, such as ketosis and fatty liver. Maintaining appropriate body condition throughout the dry period and ensuring cows don’t calve down in excess body condition will go a long way to achieving that goal. Minimizing the mobilization of body fat is the key target for reducing cases of ketosis and fatty liver. Additionally, promoting dry matter intake and roughage intake will also aid in preventing DAs.
Content, as well as type of, dietary energy supply is important with regards to reducing the amount of body tissue a cow needs to mobilize in order to meet demand. Feeding grain during the close-up period and partially introducing the animals to the lactation ration are often practiced not only to close the gap between energy supply and demand, but also to avoid an abrupt change of diet, which compromises the rumen and further stresses the animal. However, excessive grain feeding will obviously cause more issues, e.g. acidosis, than it solves with regards to rumen function, so a balance needs to be struck. Acidosis will increase the risk of laminitis, as well ketosis and other health issues, so rumen health is critical.
Cow comfort and minimal stress (both environmental and physiological) should be inbuilt into transition period management. Adequate space and a clean, dry, well-ventilated housing area are important and allowing very close-up and freshly calved cows to be in close proximity to the lactating herd will reduce stress.
Ultimately, metabolic disorders are interrelated and occurrence of one increases the risk of others. These disorders cost producers money, but often the true cost is more than simply treating the single disorder, not to mention the welfare aspect. Prevention is, as always, better than cure and many management strategies exist to reduce the risk of disease and cost.
References available upon request.