Hypocalcemia is a very important determinant of fresh cow health and production. The prevalence of subclinical hypocalcemia (SCH) is anywhere from 50-90% in today’s dairy herds and contributes to a much higher loss on dairy farms than that of clinical cases. Therefore, it is critical that a strategy is implemented on all farms to minimize SCH, so cows are not hindered in their ability to produce and stay healthy.
Today, there are two commonly known pre-fresh dietary alterations that work to eliminate hypocalcemia.
1. Supplementation of anionic salts and/or minerals containing hydrochloric acid to lower the dietary cation-anion difference (DCAD) – requires keeping potassium levels in the ration low. The process of acidifying to cow’s blood works to attract calcium, which is “basic” in pH, into the blood.
2. The low calcium approach, the restriction of dietary calcium pre-fresh (under 20 grams of available calcium per day). This hormonal approach is commonly regarded as the most effective way of managing hypocalcemia and SCH in transition cows. However, it has become impractical to utilize this method when feeding today’s high producing cows. This is because the feed components and the quantity of them needed, bring too much naturally available calcium to the ration.
X-Zelit was developed to revive the well-known and effective low calcium approach. X-Zelit is a calcium binder, that works to bind the remaining amount of calcium after all supplemental sources have been removed. During the pre-fresh period, X-Zelit binds this excess calcium from the close-up ration in the small intestine. The result is that there is little to no calcium in the ration available for absorption.
This process of restricting dietary calcium simulates exactly what happens at calving. When calving nears, a massive amount of calcium is needed within a short period of time to produce milk and colostrum for the calf. This demand causes the cow’s blood calcium levels to drop sharply (commonly below SCH levels and sometimes below clinical hypocalcemia levels). This drop in the blood calcium level is what activates the parathyroid hormone (PTH). The PTH is the hormone that is responsible for regulating calcium levels in dairy cows and does this by mobilizing calcium from her body reserves (bones). Activating the PTH before calving, when her demands are still low, means that the cow is already mobilizing calcium from her body when calving arrives and that she can meet the necessary calcium demand without developing SCH or hypocalcemia.
X-Zelit has undergone several studies (University and practical) and is currently undergoing a trial at Cornell University with results expected to be revealed by the end of 2017.
Use.
X-Zelit is added to the close-up ration at the rate of 17.6 ounces/500 grams per cow per day for the last 14-21 days before calving.
When using X-Zelit, no other methods of prevention are necessary i.e. calcium boluses or acidification of the ration. Since there is no need for a negative DCAD, the pH levels do not have to be monitored and the need to keep potassium at low levels is also not necessary.
Source: AgPR