Minerals are essential components in the building blocks of enzymes, hormones and cells. They are required for optimum growth, muscle and nerve function at varying levels according to the cows requirements, which will vary according to pregnancy status, milk production level and growth rate. These all have a significant effect on animal performance.
The bioavailability of trace minerals fed to ruminants is dependent upon the source as well as amounts of other trace and macro elements in the diet. Attempting to improve the trace mineral status of an animal by feeding higher levels of inorganic sources (e.g. sulphates and oxides) not only increases costs but also creates imbalances and can act as an antagonist with other trace minerals, increasing excretion of these minerals into the environment.
It is understandable that during tough economic times (high feed costs and low milk prices) one is tempted to remove costs from the diet and minerals are often considered. The long term impact of incorrect or reduced mineral supplementation on herd health and overall performance should first be carefully examined before removing them from the diet. Dairy health and economics experts caution against cost reductions in key areas such as nutrition and cow comfort that may compromise herd health and lead to lower milk production, offsetting any short term savings. Trying to save 30 – 50 cents per cow per day could result in increased somatic cell counts, delays in conception and other health issues that cost more than 50 cents per cow per day. Dr Mike Hutjens (University of Illionois, USA) states “Dairy farmers must make economical, sound feeding decisions which return a profit when milk prices are either high or low”. Decisions based on return on investment are good decisions and these shouldn’t change during low milk price (or high feed price) seasons, therefore feed additives (including minerals) should be strategically included once you are sure they can provide a research based profitable benefit-to-cost ratio of 2:1 or greater.
Cows will always notice sudden diet changes and the resulting stress may challenge a cow’s immune system, compromising herd health and performance. Unfortunately the signs of inadequate mineral intake go unnoticed in the short term, as producers are under pressure to maximise milk production at a lower cost. The challenge still remains one of keeping cows healthy and getting them into calf sooner. The most effective way to reduce feed costs and improve milk income of the dairy herd is to increase milk yield and improve the efficiency of milk production. Increased milk production is a function of a healthier herd, through; stronger immune function; improved claw and udder health and improved reproductive performance.
Zinc is one trace mineral that gets a lot of attention as it plays an important role in over 300 enzyme systems in the animal body. There is very interesting new and relevant research linking to zinc to critical immune functions that can significantly improve production efficiency. A healthier cow ultimately consumes less feed as she is more efficient in utilizing available nutrients from the same mouthful of feed as an immune-compromised cow. A recent study by Nayeri et al (2014) determined the optimal level of zinc amino acid complex for lactating dairy cows and the results showed that by improving the zinc supply to the animal, through an effective source can have positive implications on milk production through improved feed efficiency (Figure 1), as well as improved fertility and decreased linear milk somatic cell count scores.
Figure 1. Effect of supplemental complexed zinc levels on feed efficiency
Reference available on request
Balancing the rations of dairy cows requires that we not only balance to deliver proper amounts of amino acids, energy, carbohydrates and fats but that our aim is also to deliver the correct amounts of macro and trace minerals in forms that the animal can utilize. “Dairy producers should realise that high producing cows always make money regardless of milk price” says Dr Hutjens. Therefore it’s important to continue focussing on milk production and not be tempted to take short term shortcuts that could jeopardise herd health and productivity.
Jackie Tucker (Pr. Sci. Nat. 400144/14) is Ruminant Nutritionist at Chemuniqué and has 9 years experience working in the field of trace mineral nutrition as well as 5 years in dairy cow lameness. Her focus is on technical support to customers and producers on optimised trace mineral supplementation together with providing solution based strategies that add value to the dairy industry.