Winter crop transition puzzle
May 2 2020
To successfully transition cows to winter crops, all the jigsaw pieces need to be considered. DairyNZ’s Maitland Manning explains.
Farmer experience, backed up by Pastoral 21* research, shows that efficiently transitioning cows on to crop is critical in achieving profitable winter grazing, strong animal health and a targeted body condition score (BCS).
Cows must be transitioned onto winter crops to allow their gut bacteria to adjust to a new feed source. Transitioning onto brassicas (kale, swedes, turnips and rape) can be completed over a shorter timeframe than fodder beet. However, a poorly managed transition can result in sick or dead cows. Acidosis, for example, can cause lowered intakes, damage to the rumen and livers, and even death. When transitioning, consider the following puzzle pieces.
1. Have different plans for different crops
Fodder beet has a higher risk of acidosis, so we recommend a transition period of 14 to 21 days. Kale can have increased concentrations of nitrates at the start of winter, so transition over seven to 10 days. For more information, go to the Transitioning on to winter crops fact sheet at dairynz.co.nz/p21 and/or talk to your seed representative or consultant for advice on managing these risks.
2. Use accurate crop yields
Accurately measure and round up crops’ dry matter (DM) yield values for the transition area. Even a small miscalculation in allocation can result in acidosis (especially with fodder beet).
3. Adjust crop-to-supplement ratios
To allow cows’ gut bacteria to adjust gradually, decrease their supplement and pasture intake, and increase their crop allocation over the transition period. For fodder beet, increase by 0.5kg DM/cow/day. For kale, increase by 1kg DM/cow/day, with the rest being pasture and supplement. Make sure you offer enough crop and supplement and/or pasture to avoid BCS loss and health risks during the transitioning.
4. Improve crop utilisation
Reduce fodder beet animal health risks by making sure cows eat the leaf and roots together. Use long and narrow breaks, so all cows can access beet at the same time and dominant cows don’t gorge themselves. Also, use back-fencing to stop cows from moving back across the paddock and causing damage.
5. Reduce cow stress during transitioning
If possible, dry off cows at least a week before transitioning. On their arrival, allocate pasture and supplement, then transition them to crop the next day.
6. Help naive animals
For fodder beet, encourage naive animals by kicking some of the plants out of the ground, then chopping or slicing the beet with a spade.
7. Manage the mob
Provide enough crop face so all cows have access, avoiding heifers being bullied off the crop.
* a collaborative project managed by AgResearch, and involving DairyNZ, Fonterra, Dairy Companies Association of New Zealand, Beef + Lamb New Zealand, Ministry of Business, Innovation and Employment, PGG Wrightson and Blue Pacific Minerals.