Wheat byproducts

Other Names: wheat shorts, wheat middlings, wheat bran, wheat millrun, wheat screenings

Nutritional Characteristics:

During the processes of cleaning wheat and subsequent manufacture of flour, up to 40% by weight is classified as by-product material. There is considerable variation in the classification and description of these by-products, and great care must be taken when formulating with wheat by-products in different countries. Traditionally there were three major by-products, namely wheat bran, wheat shorts and wheat middlings. Bran is the outer husk, and so is very high in fiber and rarely used in poultry diets. Unfortunately, in many countries the term wheat bran is used to describe wheat middlings. A check on crude fiber level of wheat by-products is necessary to ensure correct terminology. The finer material removed during bran extraction, was traditionally termed wheat shorts. As wheat is ground through a series of grinders of decreasing size, middlings are produced, most of which is extracted as flour. Wheat middlings are the major by-product from the final extraction of flour.

In the U.S.A., the term red-dog was sometimes used to describe the very fine material extracted from 'red' wheats, and was similar to shorts. Today most by-products are combined at the flour mills, and commonly called wheat shorts. The only other by-product produced in reasonable quantity is wheat screenings, which as its name implies, is material removed during initial cleaning and separation. If screenings are composed mainly of broken wheat kernels, then their nutritive value is little different to wheat.

Wheat by-products such as shorts can contain very high levels of 'natural' phytase enzyme. When more than 15% shorts are used in a diet this endogenous enzyme can be greater than levels of commercial phytase added to the diet, and so influence assay results. While endogenous phytase levels are high, it is questionable if this enzyme is beneficial to the bird at the pH of the proventriculus or small intestine.

Wheat shorts: Shorts are the major by-product of flour manufacture and since they are usually a composite of various fractions, nutrient profile can be variable. The major difference will be in the quantity of bran included in the material, and so this directly influences its energy value. If wheat shorts contain much more than 5% crude fiber, it is an indication of a greater proportion of bran-type residues. Dale (1996) suggests that the metabolizable energy value of wheat byproduct is directly proportional to its fiber content, and that ME can be described as:

With an average fiber value of 5%, ME is around 2370 kcal/kg. However, it is common to see a range of 3 to 10% CF depending upon flour manufacturing procedures, which equates to a range of ME values of from 1570 to 2700 kcal/kg. Measuring crude fiber level of wheat by-products is obviously important in quality assurance programs. As described previously with wheat, most by-products will contain xylan, and so xylanase enzyme is advisable if inclusion levels are >15% for young birds or > 30% for birds after 4 weeks of age.

Wheat bran: The main characteristics are high fiber, low bulk density and low metabolizable energy. Bran is however, quite high in protein, and amino acid profile is comparable to that seen in whole wheat. Bran has been claimed to have a growth promoting effect for birds which is not directly related to any contribution of fiber to the diet. Such growth promotion is possibly derived from modification of the gut microflora. The energy value of bran may be improved by up to 10% by simple steam pelleting, while the availability of phosphorus is increased by up to 20% under similar conditions. Bran would only be considered where limits to growth rate are required, and where physical feed intake is not a problem. High bran diets promote excessive manure wetness, and transportation costs of bran diets are increased in proportion to the reduced bulk density of the diet.

Wheat screenings: Wheat screenings are a by-product of the cleaning and grading of wheat that itself is usually destined for human consumption. The product is therefore available in most countries that have significant wheat production. In addition to broken and cracked wheat kernels, screenings will also contain wild oats and buckwheat as well as weed seeds and other contaminants. The higher grades (#1 or #2) contain significant proportions of wheat, and so their nutrient profile is very similar to that of wheat. The weed seeds, depending upon variety, may be of some nutritional value. Since certain weed seeds produce a feed-refusal type reaction in layers, only the highest grades should be considered for high producing stock. The weed seeds can pose problems to arable farms that use manure from birds fed coarsely ground diets containing screenings, since some of the weed seeds can pass undamaged through the digestive tract. The level of screenings used in finisher diets of meat birds should also be severely limited, since breakage of the gut during processing leads to fine particles of black weed seeds adhering to the fat pads of the bird - such birds are easily recognized and often condemned due to fecal contamination. Number 1 and 2 grade screenings can be used up to 40% of the diet for broilers and layers.

Potential Problems:

The fiber content will directly influence energy value. With wheat screenings there will likely be some weed seeds present, and these may cause feed refusal.

Shorts

Screening

Bran

Shorts

Screenings

Bran

Dry Matter

90

90

90

Methionine

0.21

0.21

0.10

Crude Protein

15

15

16

Meth + Cyst

0.40

0.42

0.20

Metabolizable Em

rgy:

Lysine

0.61

0.53

0.60

(kcal/kg)

2200

3000

1580

Tryptophan

0.21

0.20

0.31

(MJ/kg)

9.20

12.55

6.61

Threonine

0.50

0.42

0.34

Calcium

0.07

0.05

0.10

Arginine

0.80

0.60

0.85

Av. Phosphorus

0.30

0.20

0.65

Sodium

0.07

0.08

0.06

Dig Methionine

0.16

0.15

0.08

Chloride

0.10

0.05

0.20

Dig Meth + Cys

0.30

0.32

0.15

Potassium

0.84

0.55

1.20

Dig Lysine

0.48

0.39

0.42

Selenium (ppm)

0.80

0.57

0.92

Dig Tryptophan

0.15

0.15

0.24

Fat

4.0

4.1

4.5

Dig Threonine

0.41

0.31

0.28

Linoleic acid

1.6

0.7

1.7

Dig Arginine

0.71

0.52

0.79

Crude Fiber

5.0

3.0

12.0

Gaining Weight 101

Gaining Weight 101

Find out why long exhausting workouts may do more harm than good. Most of the body-building workout and diet regimens out there are designed for the guys that gain muscle and fat easily. They focus on eating less and working out more in order to cut the excess fat from their bodies while adding needed muscle tone.

Get My Free Ebook


Post a comment