TECHNICAL ARTICLES Dairy

Dairy Concentrate Mineral Packs – Are They Necessary?

Since the Large Herds Conference at Langebaan during February 2005, there has been much talk in farming circles on mineral supplementation of feed. The points of view of some of the speakers at the conference were certainly controversial, especially in relation to the information we are exposed to from mineral companies, as part of their marketing drive. Recently in the dairy feed industry, there has been much focus on trace mineral nutrition. Organic minerals have received much attention. Some feed companies have even made the inclusion of organic mineral packs standard in some rations. This has caused some re-evaluation of the mineral nutrition route that we seem to be on.

Return on investment determines decisions made on farm. Organic trace minerals push the price of feed up and the benefits are very difficult to quantify because of the time it takes for improvements in dairy cow performance to become evident. Many of the possible improvements, such as reduced lameness and infertility, affect the bottom line indirectly. Changes in cow performance can be explained by a number of factors on the farm, and it is seldom that one can attribute anything to one variable.

This frequent intangibility of benefits associated with trace mineral nutrition often makes it difficult for farmers to invest in it, especially when the milk price seems to be ever decreasing in real terms. Lowering cost of production is becoming increasingly important. There is limited money to invest in improvements, particularly if they are only marginal. The basis for mineral inclusion rates for the pasture based dairy cow is often a bit of a ‘shot in the dark’. This is because very little consideration is given to the minerals present in the pasture. In fact, these minerals are largely ignored. Inclusion rates are based on NRC requirements. Trial results are often obtained from TMR herds in the United States, where cows produce vastly more milk than those on pasture based systems.

The major advantage of organic minerals is that they are a ‘safe’ way to add more minerals to the diet as they are not supposed to interact with other minerals. This means that the cows will actually absorb what we feed them instead of the minerals becoming unavailable, as can happen with inorganic minerals. The question is, how severe are these mineral interactions on KwaZulu-Natal and Eastern Cape dairy farms? How much of these extra minerals that are fed are actually needed by the cow? Are all the minerals being fed necessary on each farm? Would one do better to invest money in other forms of mineral supplementation, such as trace mineral injections at critical points along the production cycle? Trial results from pasture based dairy farms should be accompanied by on farm roughage quality analyses.

Determining the concentration of minerals of on farm roughage is expensive and difficult. Better pasture and fertiliser management can often overcome certain problem areas in mineral nutrition. There is very little information on the trace mineral concentration of South African pastures. Although it would probably not be feasible to develop customised mineral packs for individual farms, getting a better idea of pasture mineral status may be a way forward to more economical mineral supplementation in the long term.

Without measurement, we cannot improve. Just as benefits such as reduced lameness and improved fertility are monitored, the efficiency of investments in minerals related to the diet must be measured.

The problem is that we do not know enough to make radical decisions, such as removing mineral packs altogether, and we won’t know until we develop effective monitoring systems.

Mineral nutrition is not simple on the pasture based dairy farm. As with all nutrients, a compromise needs to be made between pasture and animal performance. The following table comes from the “Use of Trace Elements in New Zealand Pastoral Farming” and illustrates essential nutrients and quantitative discrepancies between grass and dairy cow requirements. In addition, bovine requirements according to Puls (1994) are given in the last column.

TABLE

* Puls (1994)

From the table it is evident that much about mineral nutrition on pasture based systems is unknown and that there are major discrepancies on mineral requirements between literature sources.

Organic mineral packs may be useful in hedging your bets where there are so many unknowns in that they are a less harmful way of potentially overfeeding minerals and they may be overcoming major shortfalls on certain farms. The only way for us to be sure is to devote some time to on farm research.

Date published: 2005-07-22

Author:
Jane Holiday

Publication:
N/A