Waikato Milking Systems product and project manager Andy Geissmann believes there’s plenty of scope for Kiwis working in the emerging sheep and goat dairy sectors to export.
It is tempting to make this assumption, given the limited research on goat nutrition, however in mineral nutrition goats have very different requirements.
Based on a goat’s production level when related to body weight and feed intake, these small ruminants are probably better compared to the ruminant equivalent of an F1 racing car. Just as you wouldn’t run a high performance car on low octane fuel, you shouldn’t feed your goat the same way as you would cattle and sheep.
Goats have different and very specific nutritional requirements. If these requirements are not met, the animal will not perform to its full potential, and worse still will be subject to a higher level of disease.
The interesting thing about goats is that their requirement is both higher and lower depending on the element in question. While their milk is in many ways more nutritious than that of a dairy cow, nature has at the same time designed the animal to survive under very different conditions, and on a very different diet from that of a cow.
So what are the mineral requirements of dairy goats?
Let’s start with one of the key macro elements: phosphorous. Goats typically have a lower requirement for phosphorous from that of dairy cattle. They seem to be better at recycling it and while they have higher levels in their saliva, losses during rumination are lower than that of a cow.
In contrast to this, their calcium requirements are quite high and should be set at about half the total phosphorous level in the diet based on the feed ingredients.
We consider it is always a good idea to supplement some vitamin D in the diet to ensure dietary uptake of calcium is maximised, particularly if your goats are housed in sheds. Where we as humans are relatively hairless and can therefore very efficiently synthesise vitamin D from sunlight, animals with fur coats, such as goats, are up to 80% less efficient at synthesising the active form of this element.
Recently we have implemented some anionic salt blends into goat feeds during late gestation to maximise calcium uptake at kidding and early lactation. This is based on research that proves this approach works equally well for goats as for dairy cattle. The use of anionic salts in the transition period also stimulates rumen recovery earlier and allows higher energy absorption in the early lactation.
Dairy goats have similar macro mineral and vitamin requirements to dairy cattle
For example, if a reasonable level of grass makes up a portion of the diet, then potassium levels are normally well covered. Green pasture also supplies high levels of vitamin E, (180 – 350 mg per kg/DM, silage 80 – 150mg) and this is usually more than enough to cover requirements. Likewise for vitamin A, ruminants are normally very efficient at synthesising good levels from the high natural carotene levels supplied in green grass.
Goats are generally slightly more efficient at absorbing magnesium than dairy cattle, however we normally suggest similar levels are fed, 0.22 – 0.28% Mg on a per kg of dry matter basis, on the higher end during the transition and early lactation period. Sodium and chloride requirements are also similar, if a little lower than those required by cattle.
However, dairy goat trace element requirements are very different from those required by other stock. Goats have much more specific requirements here.
Copper requirements for a goat are many times higher than that required by sheep, and are thought to be much higher than the requirement in cattle. Where a goat differs from cattle is in the liver storage department. It has been shown that a goat has less than 1/10th of the copper liver storage capacity of that of cattle on a liveweight basis.
While goats have this very poor ability to store copper they at the same time have a very high requirement for copper and suffer much worse when copper-deficient. We have found the best way to deal with these relatively high demands is by the use of the highly efficient chelated forms of the mineral. In this way we can better utilise the natural storage capacity within every cell of the body without the increased risk of toxicity. Chelated minerals that are bound to natural amino acids are much better absorbed and translocated, and are more efficiently stored throughout the body.
The same principle applies to the mineral zinc, which is second only in importance to copper in goats. By utilising chelated forms of the mineral that work well with copper, we can ensure adequate levels of bioavailable zinc are efficiently translocated to every cell in the body. Good levels of bioavailable zinc raise the body’s level of immunity, improving reproductive performance and hoof integrity.
The other all-important mineral for goats is selenium; being a high-performance animal with a high metabolic rate, goats have a high requirement for this element. For our goat supplements we tend to favour the form of the element that is naturally synthesised by plants, that form being selenomethionine. This natural selenium protein is formed during plant growth when some of the sulphur is displaced from the amino acid ‘methionine’ and replaced with selenium. This same product can also be synthesised by using a yeast culture, bringing about the same process under very controlled conditions. This is the form of selenium we favour as a selenium source in all our goat blends. Selenomethionine yeast is guaranteed to deliver high levels of very bio-available selenium in a form that can be more efficiently utilised and stored by the body.
• Chris Balemi is the managing director of Agvance Nutrition