Feed assessment requires proper procedures

Lower quality feed can lead to a range of problems in cow herds, including more sickness and lower conception rates.

Instead of three- to five-percent open cows, eight percent may fail to get pregnant, said beef and forage specialist Barry Yaremcio of Alberta Agriculture.

“With the shortage of vitamins and poor quality forage that has been rained on, there is higher calf mortality and morbidity,” he said.

Calves and heifer replacements may not grow as well. Thin cows need more feed to stay warm over the winter, he said.

“A cow that is 200 pounds light will need an extra 1,400 lb. of hay, not to gain weight but just to stay warm over the winter,” he said.

This year, there are more mycotoxins, fusarium and ergot that can all affect animal health. Green, blue, red or pink colour in forage could indicate potential problems.

Protein levels are down by 25 percent compared to normal years so supplements may be needed.

All those hazards mean feed testing is a good idea this year.

The Alberta Agriculture program Cow Bytes costs $50 and provides good value when it comes to balancing rations and calculating costs on all types of feed, he said.

Yaremcio explained the best feed testing techniques in a recent Alberta Agriculture webinar.

Core samples from stored forages are best rather than grabbing handfuls of feed. Core sampling tools are available from government offices or forage associations.

For other feeds, random samples collected from silage pits or in the field are advised.

A silage probe can be used, but it is difficult to gather good samples.

Yaremcio suggested collecting samples when the silage is being packed.

Collect a 20-litre pail with a lid at the unloading area. If this is done at the time of harvest, take a handful out of every second or third load to the pit. Keep the pail sealed. Mix the contents and fill a bread bag halfway to obtain a sample for testing. Squeeze the air out of it and freeze it to maintain quality. If the results come back before feeding, it is an easy way to determine which mineral and vitamin supplements are needed.

If the silage is already stored, take 20 samples from the face of the silage pit. Collect the samples in a W pattern, going up and down across the face of the pit. Dig in with fingers to get a sample from inside because the outside quality is lower. Seal in a plastic zip-lock bag or bread bag and freeze it.

Feeds still in the field

To get a representative sample of swaths, pick three to five plants from the middle of the windrow. If there are brassicas, select those plants in the percentage that they are in the stand. Get 20 locations throughout the field. Try to stay away from areas with gumbo soils or saline seeps in the field.

If the sample is wet, spread the plants out on a table or tarp to dry to prevent mould forming before sending to the laboratory.

Crop regrowth is occurring this fall due to extra moisture. Plants at the four-leaf to heading stage provide high quality forage that is good for lactating cows or growing calves. To assess the quality, cut the plants seven to 10 centimetres above the ground to reflect what the cow is eating. Submit half a bread bag full of material. Do not send roots or dirt. Lay it out so it dries before submitting.

Grazing corn

The quality is variable and it is hard to determine what the cows are eating. Cobs and leaves have the highest quality and are the first things cows will eat. Stalks are of the lowest quality.

Cut stalks 15 to 30 cm above the ground and submit the entire plant. Collect eight to 10 plants from different parts of the field and then run the samples through a wood chipper or a silage cutter to submit a sample. Mix up the material and send half a bread bag full for analysis.

Dormant season grazing

Select plants from random parts of the field. Clip samples to the height cows are expected to graze. The highest nitrate levels will be in the 10 to 15 cm of plant closest to the ground. The quality will change over time and generally decreases as winter weathering continues. The least mature plants have the highest quality nutrition, but will be the first plants to decrease in quality.

Cereals grains, pellets and supplements should also be tested whether they are home-grown or purchased. Collect samples in the same way as other forages to get a representative sample of what is being used. Take multiple samples and put them into a pail. Submit a bread bag filled to one-quarter for analysis. Keep a sealed portion of the sample and label by date, invoice and product, so if there is a problem it can be taken back to the supplier.

Send samples by courier, priority post by mail or deliver in person. Send samples on a Monday or Tuesday, if possible, because if it is sent at the end of the week, there will be a delay and the sample will not be as fresh. This is less important for dry feeds but more critical for frozen silage samples.

At the laboratory, samples are ground and placed into 30-gram vials. Analysis is carried out on very small amounts.

The minimum request for analysis should include the levels of:

  • moisture
  • protein
  • calcium
  • phosphorus
  • magnesium
  • potassium
  • sodium
  • acid detergent fibre measures the least digestible portions of the forage plants, such as cellulose and lignin; high ADF indicates poor digestibility of the feed
  • neutral detergent fibre indicates the amount of fibre content in the plant; high levels of NDF above 70 percent will restrict animal intake and more mature forages will have higher NDF levels

Other considerations this year include monitoring bales for overheating or nitrates present in hailed or frozen product.

A heated bale may smell sweet or like tobacco. Soluble protein may be tied to the fibre and is less available to the animals. Ten cm of spoilage on the outside of the pail indicates 20 to 24 percent of the bale weight is affected.

Waste is reduced if the bales are covered or stored in a shed.

Two-year-old hay has a reduced bale weight, protein and energy due to weathering, leaching of soluble proteins and carbohydrates. Fibre goes up because of the loss of the other nutrients.

Cocktail mixes may contain canola or brassicas like turnips. These plants are sulfur accumulators that could cause polio. If using a salvaged canola crop for feed, have sulfur levels assessed.

Copper, manganese and zinc are deficient in Western Canada. Cobalt and iodine are known to be low in feeds grown in Western Canada so supplements are needed.

Selenium tends to exist at very low levels in most areas of the West, so producers should supplement 100 percent.

The feed test should also indicate sugar and starch levels.

Check for the percentage of rumen degradable protein and undegradable protein. Some of these are critically important to know when feeding dairy cows or horses.

Degradable and undegradable protein is also needed for evaluation of the ration for growing calves or replacement heifers.

The accuracy of analysis depends on the samples and the type of tests. The laboratory may use near infrared spectrometry (NIR) and/or wet chemistry.

There is no difference in measuring protein and energy but minerals are less accurate under the NIR test. The tests could reveal large differences in calcium, phosphorus and magnesium and this could affect the cattle. Improper levels could place cows at risk for milk fever or winter tetany.

For specific details on feed values check out the Beef Cattle Research Council’s website here.

About the author


Stories from our other publications