Wheat: Frozen Wheat and Bushel Weight (Nutrition Update, Volume 15)

Frozen wheat is once again a concern for people feeding poultry flocks in Manitoba. Fortunately, research from the University of Saskatchewan helps to answer questions about feeding the value of frozen grain.

In a 1992 study conducted by Hank Classen, Pierre Hucl, Geoffrey Irish, Tom Scott and Marylou Swift, the effect of the bushel weight of frozen grain was investigated. A sample of frozen, hard red spring wheat was obtained from a single field seeded to Makwa wheat. The grain was separated into five groups based on bushel weight (55, 58, 62, 64 and 65 lbs. /bushel). For each bushel weight category, protein, starch, non-starch polysaccharides, cellulose and kernel size were measured. In broiler feeding trials, apparent metabolizable energy on a dry matter basis and gut viscosity were determined for wheat from each bushel weight category – both with and without arabinoxylanase enzyme added.

As expected, kernel size, starch and protein increased with increasing bushel weight (see Table 1). Non-starch polysaccharides and cellulose were not consistently affected by bushel weight. Gut viscosity did not vary with bushel weight but was reduced markedly by enzyme addition to the feed. In the absence of feed enzyme, bushel weight did not affect apparent metabolizable energy but when enzymes were added energy level did increase with bushel weight. When feed enzymes were used, the apparent metabolizable energy level of the lowest bushel wheat (55 lbs.) was still greater than the highest bushel weight wheat (65 lbs.) without enzyme added.

This research indicates that over the range of 55 to 65 lbs./bushel, the bushel weight of frozen heat has a limited impact on feeding value. This finding will not be true for all samples of frozen wheat. Earlier research from Ray Salmon at the Ag Canada research centre in Saskatchewan indicates that the metabolizable energy level in frozen wheat can be reduced in samples with bushel weight below the 55 lbs. /bushel. In Ray Salmon’s research, the drop in metabolizable energy was dramatic below 50 lbs. /bushel.

Table 1. Characteristics of frozen wheat separated by bushel weight 

Bushel Weight (lbs/bushel)
55 58 62 64 65
Kernel weight (mg) 27 31 34 39 42
Starch (%) 64.2 65.0 66.5 67.6 68.2
Protein (%) 13.3 13.2 13.3 14.0 14.4
Non-starch polysaccharides (%) 11.4 12.2 10.5 10.5 10.8
Cellulose (%) 2.0 2.4 2.1 2.3 2.2
AME, kcal/kg - No enzyme1 2900 2900 2850 3050 3050
AME, kcal/kg - With enzyme1 3250 3100 3300 3300 3300
1Apparent metabolizable energy on a dry matter basis for 17 day old broilers
Prepared By:  Carlyle Bennett, M.Sc.
Nutrition Update
Volume 15 No.2, November 2004