Editor’s note: This is part of an article recapping some of the points made during a July 29 webinar. Some of the information from the webinar was in a story in the Aug. 9 edition of this paper and the full webinar can be found on the BCRC Blog and locating the Aug. 10 entry titled, ‘Experts Respond to Drought Questions.’
During the webinar, producers were warned to be aware of additive effects and interactions.
Even if feed and water sources are each within tolerable levels for potential toxins like nitrates or sulphates, remember that cattle consume both water and feed. The combination of the two could have additive effects resulting in negative animal health consequences or even death.
This is even more important with alternative feed sources. For example, canola tends to be naturally high in sulphates. If you are feeding salvaged canola but your water source is also high in sulphates, the combination can result in overexposure.
Cattle may show immediate signs of sulphur toxicity (such as neurological symptoms such as twitching, vision impairment or staggering). Mineral interactions can also ensue. For example, copper levels may be acceptable in both the water and the feed, but excess sulphates (or molybdenum) can tie up that copper and result in lower pregnancy rates next year, or tied up vitamin E and selenium increase the risk for white muscle disease in calves next spring.
There may be enough nutrient in the feed, but if that nutrient is bound up by another feed ingredient and can’t be absorbed or used by the animal, it will still be deficient. This is known as a secondary deficiency.
Producers should also be cautious when feeding weeds.
Certain weeds (including dandelion, lamb’s quarters, and kochia) can be very nutritious for cattle, but use caution. Kochia tends to be high in oxalates, which can bind calcium and result in a secondary calcium deficiency (again, the feed test result may indicate that calcium levels in the ration are adequate).
Make sure you are aware of poisonous weeds in your area. Often cattle will avoid grazing these plants in normal years, but cattle may start to graze those poisonous species in drought conditions when forage supplies are short.
A few other points to consider:
- Avoid grazing flax, it is also high in oxalates and can bind copper. If you plan on feeding flax, it is better to cut and bale it.
- When grazing salvaged feeds, make sure you are aware of any products that have been used on that crop. Fungicides, herbicides or other chemicals used on crops may have withdrawal dates for livestock consumption or may state that livestock should not graze the crop at all.
- Ammonization can be used to increase the protein content of straw. If using ammoniated feed the ration must be balanced to ensure adequate energy for cattle to digest the protein. Availability of crews can also be an issue and appropriate safety precautions must be taken.
- When grazing alternative feeds or residues, use electric fence to only allow access to small amounts of the field at a time. This will help cattle graze more efficiently but also can make supplementation easier.
- Consider weaning calves early to reduce the energy requirements of the cow herd. Ensure you run the numbers to decide what the best option is when it comes to marketing calves.
For more content related to drought management visit The Dry Times, where you can find a collection of stories from our family of publications as well as links to external resources to support your decisions through these difficult times.