Kale is Kale is Kale – Right?
Kale is a common winter feed crop for many dairy farmers. Grown and fed either on farm as part of a pasture replenishment program, on a run-off, or at graziers, it has some real benefits. Kale holds some significant advantages over fodder beet such as a much higher calcium content which replenishes reserves lost over the season, and good levels of phosphorus which commonly requires supplementation with beet. However, it doesn’t come without risks, some of which we will explore in this article.
So Kale is Kale is Kale - Right? Actually, not all kale is equal. The importance of feed analysis is highlighted by the huge variation we see between kale samples, not just between farms but also between farms and runoffs with the same soil types.
Kale is a crop with a commonly accepted nutritional mineral profile. Nevertheless we commonly see some major variations from these “average” mineral levels, particularly when it comes to sulphur and molybdenum. Copper is commonly primarily deficient in Kale. However when both sulphur and molybdenum levels are excessive this increases the risk of poor animal performance if left unsupported.
The arrow in the diagram shows the issues with most common on the left to least common on the right, but when all three occur, the additive effect depicts the highest risk with some of the consequences listed underneath.
While much focus is given to the issue of copper deficiency from high dietary molybdenum, the issue of sulphur-molybdenum complexes themselves is often ignored. Yes these are involved in further reduction of an already deficient copper intake, but importantly are toxic in their own right and if left unsupported can cause significant brain damage (polioencephalomalcia, also known as thiamine deficiency) with signs of staggering or aimless walking, downer cow and blindness.
But a lack of clinical signs does not mean there’s no impact on your herd. For so many disorders the real cost is not with those seen but in the sub-clinical cases – those with non-specific symptoms or just sub-optimal performance. Most commonly we’re talking about a higher empty rate than desired, expected or typically found.
When grazing monocultures over the dry period, getting the mineral supplementation right is really important. This ensures calving goes as smoothly as possible and more importantly, mating is not negatively affected. What’s exciting is that we are finding multiple benefits to grazing more diverse winter crop mixtures.
So how do we avoid these undesirable outcomes? The only way to know for sure is to analyse the kale on your farm. To sample we take at least six stem and leaf samples throughout the paddock/s which will give you a representative sample that can then be analysed for mineral levels. The mineral analysis will give you a clear picture about the risk and antagonisms between copper, sulphur and molybdenum.
“Average is a failing formula”, Grant Cardone. Although they might seem like subtle differences, knowing the unique mineral profile of your kale versus the “average” helps you make better decisions for the wellbeing of your animals.