Grape Marc is the focus of many phone calls I've received in the last few days. People want to know what this product is, if it can be used to feed cattle and if there is any usefulness to this as a feed.
Basically Grape Marc is the remains of wine making. It consists of the stems, seeds and pulps after the grapes have been processed for wine.
Grape Marc can be very variable in its feed value. The moisture content of this product can vary significantly depending on its processing method.
The energy and protein content of Grape Marc is also variable. Tests by state Departments of Agriculture highlights the variation in feed values of Grape Marc.
NSW DPI figures indicate Grape Marc has an average value of 50.7% DM; just over 13% CP and around 6MJ of metabolisable energy (ME).
At best Grape Marc can have a dry matter of 90%; and up to 8 MJ/ ME.
Effectively this means Grape Marc is a basic feed which can be used as a filler in a ration.
I reckon a lot of producers need to consider how cost effective this type of feed can be to their circumstances. If feed is low in Dry Matter, e.g. 50% then you needs to work out how much it is costing to actually get that feed home.
For example; if a truck load of feed is 55% Dry Matter; 45% is moisture. So for every 1000kgs on the truck, 450kgs of that load is moisture!
When you feed your stock, your are feeding a ration based on Dry Matter & MJ/ME So in the case of that 55% DM feed it might have 7MJ/ME, it works like this:
if your animal needs 80MJ/ME day (based on its weight) then it needs to eat 11kg/DM a day
based on the DM of that feed, you would need to feed out 20kgs of feed a day.
I reckon when you start looking at those quantities, and the costs associated with such a feed, you will quickly work out if it actually is the best option for you to purchase.
Grape Marc is also a feed which can pose a residue risk to your stock. You must ask for a Commodity Vendor Declaration form and make sure you keep a record of the vendor, the stock you feed and how much you feed.
The skins and seeds contained in Grape Marc can be risk for chemical residue. The Victorian DPI notes some studies indicate oil soluble chemicals can be ingested easily from grape seeds to accumulate in fat tissue.
Dairy Australia has developed some suggestions for producers using Grape Marc, which is a handy reference.
As with any unusual feed, I reckon you need to way up the costs and the risks pretty carefully before you start using it.
If you can't get a Commodity Vendor Declaration for the products you want to use, then I reckon you should avoid using that feed.
If you do your homework and work out the options, then Grape Marc may be a good choice for you. But don't rush in until you've made a few enquiries and worked out if it is the best option for you.
If you are unsure about a feed, its usefulness or its suitability for your stock, make sure you get some sound advice before spending money or taking risks with it. I reckon the drought is tough enough without the risk of feeding the wrong products.