Grape crops in the Hunter and other areas that have been affected by 'smoke taint' and can no longer be made into wine and are likely to be used for livestock consumption. While grape marc is often used by feedlots and also by the wider industry during droughts, feeding the actual grapes is unusual and poses other questions.
For example, the grapes will contain sugars, that will probably be fermented to alcohol if piled in a paddock. While there is a potential for acidosis from the sugars and drunkenness from the alcohol, especially since the harvest material will be very palatable, best guess is that this is unlikely if the normal precautions of offering new feeds is followed ie introducing slowly, not feeding to hungry stock, shandying with other feed etc.
Maize silage with around 4% alcohol has been feed to cattle with minimal side effects, apart from making them a little dozy and difficult to move!!
Grape prunings that include whole grapes will have more energy than grape marc due to the presence of sugars / alcohol. At this point however, it is probably best to still consider the material a roughage source for a couple of reasons:
- Grape marc is generally of low value, so the addition of the grapes, with high moisture content on overall feed quality is unknown. Hunter Local Land Services is hoping to test samples to provide more information.
- The grape prunings are only likely to be available for a short time, unless made into silage. Since it generally takes 2-4 weeks for rumen microbes to adjust to new feeds, fully digest them and utilise their nutrients then the benefits may largely be missed.
- Its possible that grapes will be pruned at different stages- smoke affected crops pruned early for example- and so the level of sugars and other nutrients in the grapes may vary.
The residue risks associated with feeding whole grapes is unlikely to change due to the inclusion of the whole grapes (covered in a recent article by LLS District Vet Jillian Kelly). However industry consultants in the Hunter for example, indicate that due to the dry conditions, very few fungicides or other treatments have been used and so the risk of chemical residues is much lower this year.
Where a Commodity Vendor Declaration or the treatment schedule for the grape harvest material is not available, they should only be fed to stock not destined for processing in the foreseeable future, for example cows and calves, so that stock can be fed for 60 days on pasture or 'clean' feed to minimise residue contamination, prior to processing.
For more information on livestock nutrition and feeding please contact Hunter Local Land Services on 1300 795 299 or visit us online athttps://www.lls.nsw.gov.au/regions/hunter.