Welcome to The Dairy Mail

by Gerrit Bezuidenhout

Every farmer knows that supplements are essential to keep animals in top condition. However, there are trace elements that benefit more than others, but can one find this? The Dairy Mail spoke to Dr Willie Smith, an expert in animal feed in South Africa, to learn more about the successful use of trace elements in dairy herds.

The big five
According to Smith, the big five of trace elements in supplements are those that perform the most essential tasks relating to reproduction, disease resistance and stress-related ailments. These trace elements are:

• zinc
• manganese
• selenium
• copper, and
• chromium

Although trace elements such as iron, iodine and cobalt are also mentioned, said Smith, the five above play the largest role in herd health.

The role of trace elements
"One could write books about the function and effectiveness of trace elements," said Smith, but he stressed that in this case, all five trace elements are essential for reproduction. "Manganese is very important for oestrogen production, ovulation, a healthy ovum and fertilisation to occur effectively. In addition, all four other trace elements play a role in different stages of the reproduction process and according to me are the most important in that sense." Trace elements also serves as fuel for certain processes in the enzyme and hormone systems. This is especially important in natural resistance and reproduction efficiency. Trace elements such as zinc regulate cell division in the body. For this reason, trace elements must be present in large quantities in the cow's body, especially before critical economic times.

The right trace element at the right time
Dairy farmers, veterinarians and animal science experts need to ensure that herds or herds which they are involved with, have specific, purposeful trace element supplement programmes in place. These supplement programmes should be more than just to prevent trace element deficiency and should especially focus on trace element functions of producing and reproducing cows during critical economic times. The four most important critical economic times to pay attention to are the management of supplement techniques before calving, before fertilisation, or AI, when the cows are dried, and during times of stress such as during times of active growth .

"It is important to note that some supplements should be administered four weeks prior to these events. The reason is because the metabolism of the animal takes four weeks to metabolise the trace element to the enzyme in which the trace element is active. A good example is the trace element selenium, which functions as part of the family enzymes called glutathione peroxidase. These selenium enzymes form a large part of the cellular antioxidant system, which in turn protects the cow against harmful elements, or so-called free radicals," said Smith.

One of the difficult times is when cows are dried. "The problem usually occurs during the dry period. Dry cows on dairy farms don’t always get the attention they need. The focus is always on the early lactating cows. According to research in America, we known that dairy cows lose trace elements during the dry period and early lactation period. In other words, if one were to draw a graph, one would see that the trace element curve runs downwards, as the cow is not building trace elements during this time. This is mostly because of supplements techniques during the dry season and early lactation periods, which are not completely up to scratch," explained Smith.

The risks of overdosing
Although it rarely happens, Smith accepts that trace elements are sometimes administrated too generously.

"I think we must be very honest and rather warn producers not to overdo it. The two most important trace elements which could cause poisoning – selenium and copper – in particular could be toxic if administered too generously. Fortunately, it happens rarely that we see trace elements administered too generously, since the animal feed industry very well educated. Ensure that these two trace elements are administered correctly," Smith stressed.

Different milk regions, different trace elements?
"Whether different needs of trace elements exist for different regions is debatable, but in my experience of 35 years in the dairy industry, I have increasingly found that there are not big differences between regions. However, some regions may have worse trace element antagonists than others. For example in the Southern Cape there are regions such as Mossel Bay and George area where there are high levels of iron in drinking water. Naturally, iron is a very strong antagonist for the absorption of selenium and copper in cows. This can lead to major deficiencies of these trace elements. Therefore one has to consider regions independently before compiling a supplement programme. Antagonists definitely play a significant role: When levels of iron, calcium, and sometimes sulphur or molybdenum are too high, certain trace elements, especially copper and sometimes selenium, zinc, and manganese will not be well absorbed. The reason is that the antagonists prevent trace elements from being absorbed in the gut are then excreted," explains Smith.

Stick to the correct dosage
Supplement programmes for trace element for ruminants should always stand on two legs i.e. oral supplements, such as licks, and injections. Injecting trace elements should be done four to six weeks before calving and again four to six weeks before AI to ensure optimum trace element function during calving and AI. "Good-quality injectable trace element preparations containing the necessary trace elements at the right levels, could make a positive difference, as these trace elements cannot bind in the digestive tract and efficiently used by the animals," said Smith.