Agriculture

Straw as an Alternative Roughage Source for Wintering Beef Cows

When hay supplies are low, differing options for wintering the cow herd have to be considered. Straw can be used extensively as winter feed if energy, protein, mineral and vitamin requirements are met. Straw does not contain sufficient levels of these nutrients and the use of grain, protein supplements and mineral/vitamin premixes is needed make straw-based wintering diets work well. It is critical to supply all the nutrients the animals need in order for them to maintain good health, body condition, high reproductive rates and desirable weaning weights. It is important to understand the basic nutritional needs of your animals. The nutritional requirements of the beef herd change as the animals move through different physiological stages.

The general nutritional requirements of the breeding herd are listed in Table 1. When comparing the nutrient requirements of the breeding herd to the nutritive value of straw (Table 2) it is clear that straw alone is not sufficient to maintain the animals.

Table 1. Nutritional requirements of the breeding herd1

Class

TDN%  

CP%

Ca%

P%

Mature cows
Mid gestation

50-53

7  

0.20

0.20

Late gestation

58

9

0.28

0.23

Lactating

60-65

11-12

0.30

0.26

Replacement Heifers

60-65

8-10

0.30

0.22

Breeding Bulls

48-50

7-8

0.26

0.20

Yearling Bulls

55-60

7-8

0.23

0.23

1 Nutritional requirements vary with body weight, frame size, predicted ADG and stage of production. Contact the local MAFRI GO Team Office or Centre for ration formulation services. All rations must be balanced for protein, energy, vitamins and minerals.

Physical intake of a straw based ration will be restricted due to the fibrous nature of the feed. This can create problems, particularly when beef cows increase intake in response to cold temperatures. Rumen compaction may occur if straw is fed alone with no readily available energy and/or protein supply for the rumen microbes.

Table 2. Average nutrient values of straw (100% dry matter basis)

  CP% TDN%   Ca% P%
Wheat Straw 3.9 44 0.18 0.11
Barley Straw 4.9 46 0.13 0.08
Oat Straw 4.5 48 0.26 0.10
Flax Straw 5.4 43 0.26 0.08
Pea Straw 6.4 48 0.60 0.19

During cold periods the energy component of the ration needs to increase approximately 15-20% as the ambient temperature drops to -20 to - 25 0C. In the last trimester of pregnancy the cows nutrient requirements also increase significantly. Therefore, it is important to provide higher quality feed either in the form of good quality alfalfa hay or increase protein and energy supplementation of straw diets.       

When feeding straw several factors need to considered:

  1. Feed test: straw sources (i.e. barley versus wheat straw) differ in nutritional content and digestibility. It is critical to know the nutrient content of all feedstuffs in order to provide a balanced ration.
  2. Diets must be balanced for energy, protein, minerals and vitamins.
  3. Ammoniation can increase the overall feeding value and intake of straw based diets.
  4. Grinding/chopping straw and feeding as a part of a total mixed rations will increase intakes.
  5. Check the nitrate content.
  6. A 2:1 mineral (or 3:1) will be needed. Limestone may also be required if no other forage is fed.    

Here are some different options (Table 3) for feed rations using values of $80/ton for hay, $60/ton for greenfeed, $190/ton for 20% CP grain screenings (77%TDN), $25/ton for straw, $45/ton for ammoniated straw, $3.60/bushel on barley, $280/ton for 32-10 feedlot supplement, $650/ton for mineral, $45/ton barley silage (35% dry matter), $45/ton for corn silage (30% dry matter) and $8.50/bale treating bales with liquid feed supplement (4.5-5 gallons/bale). Based on a 1400-1450 lb cow - approximate feed required pre/post lactation calving in March.

Table 3. Differing wintering ration options for beef cows (1400-1450 lbs)*           

Option 1 2 3 4 5 6 7 8
Grass-legume hay (lbs) 16 14 - - - - - 9
Barley straw (lbs) 23 - 23  23 - 22 23 18
Ammoniated barley straw (lbs) - - - - 30 - - -
Barley grain (lbs) 1.5 - 10 10 7.5 - - -
32-10 Feedlot supplement (lbs) 0.5 - 1.5 - - 0.5 - 1
Barley silage (lbs) - - - - - 45 - -
Corn silage (lbs) - - - - - - - 32
Liquid supplement (lbs) - - - 2.9 - - - -
2:1 mineral - 0.15 - - 0.1 - - -
20% Screening pellets - - - - - - 14 -
Greenfeed - 19 - - - - - -
Cost ($)/head/day 1.11 1.18 1.25 1.41 1.32 1.36 1.62 1.33

Add 5%-10% for waste depending on feeding method

in conclusion, the first step is to do an inventory of available feed supplies and feed test. This allows you to match feed available with the animal's requirements. Please contact the local MAFRI GO Office or Centre for feed testing supplies, feed sample submission and ration formulation.