In a survey of Saskatchewan forage last fall 62 per cent of the 200 bales sampled did not meet the energy requirement for a 1,350-pound cow in mid-gestation at -25 C. Only five per cent of the alfalfa, alfalfa-grass, grass and cereal greenfeed bales supplied enough energy to carry pregnant cows through the last month of pregnancy. Then winter hit with a vengeance and stayed well into spring, sending feed values down even further.
Only five to 10 per cent of producers in the province would have been aware of what their bales contained, because they are ones who bothered to test their 2013 feed supply.
2014 is shaping up to be much the same with heavy summer rains spurring lots of growth and delayed harvests and plenty of weathered feed in many areas.
You can’t avoid the weather but you can avoid shortchanging your cattle with a simple feed test so you’ll be prepared for whatever Mother Nature throws your way this winter, says Terry Kowalchuk, a provincial forage crops specialist with the Saskatchewan Ministry of Agriculture (SMA).
Grabbing samples from bales isn’t likely to do that. Leaves fall off when you pull out handfuls and you can’t reach very far into the bales.
A bale probe with a sharp cutting tip is a better solution. Inserted 12 to 18 inches into the bale it will pull out a uniform cross-cut sample of leaf and stem material.
SMA regional service centres loan out probes that fit onto a cordless drill at no charge but when you consider what’s at risk Kowalchuk figures a standard probe is a worthwhile investment for any sized operation.
The probes demonstrated at Western Beef Development Centre’s summer field day were supplied by Star Quality Samplers of Edmonton, and range in price from $135 to $400, depending on features.
The ideal is to sample each lot of hay separately. Nutritional quality varies enormously depending on the forage mix, soil type, fertility, disease, growing conditions, stage of cutting, dry-down time and condition of the windrows at baling.
A lot can cover an entire field or parts of it when cutting or baling times differ.
If you move bales to a stackyard, Kowalchuk recommends arranging them by field or lot for ease of sampling and identification. It also makes it easier to select bales of a certain quality as needed through the gestation cycle.
Probe bales from each layer of the stack to get your sample.
Round bales should be probed on the side, small square bales near the centre of one end and large square bales anywhere along the end or side.
Obviously you want to avoid sampling or feeding any mouldy material.
Sample at least 20 bales from each lot, dropping the cores into a pail as you go. Then mix them well before you pull out a composite sample to seal in a plastic bag for testing. You’ll need at least 250 grams from a probed sample, or a large Ziploc bag full of a grab sample.
Use a permanent marker to label each bag with your name or farm name, along with an accurate description of the mix of forage species in the sample, the field or stack, and sampling date.
Some people just grab samples from spots at various levels across the face of the silage during successive days of feeding.
Again, gather at least 20 samples, mix well, push the air out of the bag, label it and put it in the fridge or freezer to prevent spoilage before it gets to the lab.
With silage it’s best to test after it ferments and the pH stabilizes, which usually takes about six weeks, says Kowalchuk.
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For swath grazing, take grab samples from various slopes across the field. Avoid areas that aren’t representative, such as weed patches and saline spots. The material can be coarsely chopped with scissors and then mixed well to obtain your test sample.
The samples for the 2013 Saskatchewan forage survey were analyzed by wet chemistry at Central Testing Laboratory in Winnipeg. A basic wet chemistry package for forages (hay, silage, cereal greenfeed and swaths) for beef cattle is $32 per sample.
Wet chemistry analysis is the gold standard for feed testing, says Central Testing general manager Yvan Bruneau.
NIR costs a little less and is quicker than the three to five days for wet chemistry, but it’s more of a general estimation. It might be good enough if you’re not weighing out feed ingredients and you can decide from there if the sample needs to be retested by wet chemistry, he explains.
NIR is based on the amount of energy from the near-infrared light spectrum absorbed by hydrogen bonds in feed molecules and calibration curves programmed into the machine. The feed sample is scanned and compared to the calibration curve specific to the feed type to predict the amount of each component.
The accuracy depends on how well a feed component absorbs NIR light energy and the accuracy of the calibration curves.
Bruneau says Central Testing developed its own calibration curves built off wet chemistry analysis of forage samples representative of tame and native forages grown in Canada rather than relying on the general calibration curves that come with the machines.
NIR works well at predicting moisture and organic elements like protein, starch and fibre needed to estimate energy content and feed value. It’s weak at predicting mineral levels since minerals don’t absorb near-infrared energy unless they are bonded with hydrogen in a molecule.
Central Testing’s NIR package for hay (grass, alfalfa and alfalfa/grass), and silage (alfalfa, alfalfa/grass, barley, corn, cereal) or straw costs $23 per sample. It includes the same six minerals as the wet chemistry package: calcium, phosphorus, potassium, magnesium, sodium and salt; however, a NIR analysis with minerals analyzed by wet chemistry is available for $25.
They also test for pH in silage and nitrates in greenfeed when requested. More details are available at www.ctl.mb.ca.
SMA and Alberta Agriculture maintain an online listing of labs across Western Canada and some in the U.S. that analyze feed and water samples.
See Canadian Cattlemen, October 18, 2010, for more on feed testing methods and weather effects on forage quality.