HealthyLife
Programme for Sustainable Dairy Farming
Optimize health and performance of dairy cows by feeding the correct source of trace minerals
HealthyLife
Programme for Sustainable Dairy Farming
Optimize health and performance of dairy cows by feeding the correct source of trace minerals
Three reasons to rethink sulphate trace minerals in the dairy ration
Research into the impact of trace mineral source on health and performance of dairy cows
Findings from studies conducted by leading research universities and pioneers in trace mineral nutrition of dairy cattle suggest it may be time to rethink the use of inorganic trace minerals in the dairy ration. Dr. Scott Fry from Micronutrients presents an overview of recent research suggesting that the source of trace minerals in a dairy ration can have a big impact on health and performance of dairy cattle.
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What's the impact of the
new 8th edition of the NASEM Dairy requirements?
This is what we would like to discuss together with you during our webinar on October 4. Join Dr. Bill Weiss, Ph.D, Professor, Department of Animal Sciences, The Ohio State University and Co-Chair of the NASEM Dairy Requirements Committee, who will address the changes to the trace minerals, macro minerals and vitamins sections of the new NASEM guidelines.
Monday, October 4 2021, 10:00 AM EST (16:00 PM CET)
Before addressing concerns related including sulphates in dairy rations, it may be helpful to understand how sulphate-based trace minerals became so widely used in the dairy industry. Nutritionists have long known that supplementing cows’ diets with small amounts of copper, zinc and manganese is a vital part of supporting functions such as immunity, fertility, production and metabolism. Beginning in the 1930s, oxide trace minerals became available as a more concentrated source of trace mineral supplementation for use in cattle feeds. Sulphate trace minerals followed in the late 1940s offering producers a source of trace minerals with higher bioavailability than oxides.
Based on this difference, sulphate-based trace minerals have grown to become the dairy industry’s primary source of trace mineral nutrition. To further improve trace mineral bioavailability and effectiveness, organic trace minerals for dairy cattle were introduced in the 1970s. While many organic trace mineral sources delivered improved results, their high cost meant producers only replaced a small fraction of the animal’s total trace mineral requirement (for example 20% organics and 80% sulphate trace minerals).
Early in the 2000s, a new source of trace mineral supplementation for dairy cows became available with the introduction of hydroxy trace minerals.
The introduction of hydroxy trace minerals in dairy cow nutrition
Hydroxy trace minerals offer better mixing and handling qualities along with equal or better performance compared to higher-quality organic trace minerals. Research was conducted to compare how different sources of trace minerals work inside the cow’s gastrointestinal tract, resulting in a number of important findings.
Sulphate trace minerals have high reactivity in the rumen of dairy cows
As scientists compared sulphate-based trace mineral sources with hydroxy trace minerals, the structure of the trace minerals became an important area of focus. Sulphate trace minerals have weak ionic bonds that are significantly more soluble in water and rumen fluid than hydroxy trace minerals[1] (see figure 1). These weak ionic bonds between the metal ion and the sulphate molecule break down quickly when they encounter moisture. The release of these highly reactive metal ions can negatively react with diet antagonists, resulting in a reduction of availability of certain nutrients. Free metal ions can also have a negative impact on beneficial microbes present within the upper gastrointestinal tract of ruminants.
Figure 1, Sulphate sources of trace minerals were shown to be significantly more soluble in the rumen of cattle than hydroxy trace minerals.
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Sulphate trace minerals may harm beneficial rumen microbes of dairy cattle
Once broken down in the rumen, the zinc and copper ions originally linked within the sulphate trace mineral now possess antimicrobial properties and can harm beneficial bacteria that digest fibre. In contrast, hydroxy trace minerals have a crystalline structure and covalent bonds that make them significantly less soluble. As a result, disassociation in the rumen is minimal, thus making it all but impossible for free metal ions to be released in the rumen environment.
‘Good’ microbes in the rumen play an essential role in promoting fibre digestibility. They support the production of important volatile fatty acids used by the dairy cow for optimised productivity and well-being. As these microbes multiply and travel down the digestive tract, they become a high-quality source of by-pass protein for the dairy cow, providing about half the total dietary protein needed for milk production. Thus, a trace mineral source that interferes with microbial activity in the rumen – where 90% of digestion takes place – can interfere with the performance and health of dairy cows.
A practical observation is that sulphate trace minerals have, for many decades been used in footbaths for dairy cows for their efficacy in killing microbes. Unfortunately, the same properties that make sulphate trace minerals effective in footbaths can potentially harm rumen microbial populations.
Sulphate trace minerals have been shown to reduce fibre digestibility
It is well understood that microbial activity in the rumen is essential for optimal neutral detergent fibre digestibility, which further supports the production of important volatile fatty acids. To further evaluate the impact of trace mineral source on this process, animal scientists from multiple research universities compared how sulphate trace minerals and hydroxy trace minerals affected digestibility in the rumen and found an increase in digestibility of 1.1 to 4.6 points in case hydroxy trace minerals were used[2,3,4,5,6] (Fig. 2).
As literature and data suggest, a one-point change in digestibility can translate into an increase of 0.25 to 0.3 kg of 4.0% fat-corrected milk[7]. Thus, when sulphate trace minerals are replaced with hydroxy trace minerals, cows may see an increase in milk production.
Figure 2, Increase of fibre digestibility for hydroxy trace minerals compared to sulphates.
References
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