Straw as a Roughage Source for Beef Cattle

The nutrients contained in roughage are determined by their stage of maturity at harvest. Generally, the earlier the stage of harvest, the higher the energy and protein content will be. Digestibility and palatability will also be higher.

Straw is a roughage feed that can be used effectively in any beef cow wintering program, although additional energy and protein need to be fed to avoid impaction and ensure the animal's requirements are met. As with any diet, supplemental vitamins and minerals are recommended as well.

Straw Quality

Protein content of straws can range from one to eight per cent and fibre content from 25 to 65 per cent. This variability means it is important to have your straw supplies analyzed at a feed testing laboratory, followed by ration balancing, to meet the cows' needs for each stage of her reproductive cycle.

In general, oat straw has better feed quality than barley straw, which in turn has better quality than wheat straw. Year-old straw is often found to be more palatable than fresh straw. Straw from other crops may also be used. Pulse crop straws, such as peas, lentils, and chickpeas, have higher levels of protein and energy than cereal straws. Flax straw is very palatable and has been used successfully by cattle producers, but caution should be used if the straw is green since prussic acid may be present. Once again, a feed analysis should be carried out to determine the prussic acid levels that may be present.

Table 1. Average Nutrient Values of Various Straw (100% Dry Matter Basis)

* TDN - Total Digestible Nutrients

How straw fits into a winter feeding program

Straw is often incorporated into the feeding program during the mature cows' second trimester, in which their requirements for protein and energy are lower than late in pregnancy and during early lactation. Good quality straw can contribute up to 75 per cent of a wintering cow's diet if supplemented correctly, while a low quality straw might make up only 50 per cent of her diet. Straw is digested at a slower rate than hay, so a cow can consume less straw (maximum 1.25% of her body weight) than hay (2-2.25% of her body weight) on a daily basis.

Example: 1,200 lb. cow X 1.25 per cent = 15 lb. dry matter straw. If the straw had 12 per cent moisture content, divide the 15 lb. of dry matter intake by 88 per cent dry matter to give 17 lb. of straw intake on an "as fed" basis. Intakes will vary due to differences in the digestibility of various types of straw.

Grinding or processing straw will increase daily intakes, although she still needs additional protein and energy or problems such as impaction, malnutrition, reduced milk output and lowered conception rates will result. Another factor to take into consideration is that the cow's intake decreases in the range of 12 to 13 per cent when she is in the late stages of gestation. Her capacity to take in the bulky feed is reduced due to the space that the developing calf occupies in her abdominal cavity.

Good quality hay should be reserved for the last six weeks of and into the lactation stage. Good quality hay should also be used for the young pregnant cows, heifers and replacements that are producing a calf as well as growing themselves.

Providing a properly balanced ration.

As mentioned above, cows fed straw-based rations will need additional energy and protein. Protein sources can include alfalfa or alfalfa-grass hay, canola meal or a protein supplement. Grain or pelleted screenings are great sources of energy. A mature cow can safely consume about eight pounds of concentrate such as grain or pelleted screenings at one feeding. If the level of concentrate being fed each day exceeds that amount, consider dividing the concentrate and feed equal portions twice per day. Ionophores may be added or mixed with the concentrate to reduce the incidence of bloat.

For cows to remain reproductively efficient, it is important that they are provided with adequate levels of minerals, vitamins, and salt. Alfalfa and alfalfa-grass based rations would utilize a 1:1 mineral (equal proportions of calcium and phosphorus), while rations based on green-feed, silage, or straw with grain would call for the use of higher calcium containing minerals such as a 2:1.

A cow's energy, protein, mineral and vitamin requirements will change throughout the various stages of pregnancy and lactation as well as changes in temperature.

Additional considerations include mould. Straw that has been stored uncovered outside for long periods of time will be weathered and could produce mould. Avoid feeding moldy straw, hay or grain to pregnant cows. Molds and the toxins they produce can cause many problems (abortions, fungal pneumonia, allergic reactions, weak and deformed calves, reproductive problems, prolapse and poor performance).

Some producers have applied anhydrous ammonia to stacks of straw. The ammoniation process significantly increases the crude protein content and increases straw's digestibility and intakes. If a producer is looking into this option, it is strongly advised to contact their local livestock specialist for more information.

Example rations utilizing straw as the main feed ingredient

1,200 lb. Cow
- no wind, -20º C
- seven months pregnant
- to start calving March 15
- expected calf birth weight 85 lbs.

All amounts are per cow per day on an "as fed" basis

Rations

* The Vitamin A-D-E pre-mix contains 10,000,000 IU's of Vitamin A per kg.
- Salt should always be available on a "free-choice" basis

Example rations utilizing straw as the main feed ingredient.

1,200 lb. Cow
- no wind, -30º C
- seven months pregnant
- to start calving March 15
- expected calf birth weight 85 lb.

All amounts are per cow per day on an "as fed" basis

Rations

The Vitamin A-D-E pre-mix contains 10,000,000 IU's of Vitamin A per kg.

Salt should always be available on a "free-choice" basis
The minimum amount of mineral recommended is 1 oz. per head per day unless adequate mineral is being supplied either in fortified pellets or fortified protein supplements

Summary

A cost-effective feeding program can be designed around rations utilizing straw as a significant portion of the roughage source. Such rations can use cereal grains, screening pellets or other by-product feeds to produce a cost-effective alternative to using good quality roughages. It is important to note again, that an analysis of feedstuffs to be used should be done in order to design a ration that meets the needs of the animal and that is cost effective.