Nutrition and Management: Feeding Barley Grain - Effect of Bushel Weight

This is a fact sheet from the Nutrition and Management section of the Alberta Feedlot Management Guide,Second Edition published September 2000. The 1200 page guide is available for purchase on CD-ROM.

Take Home Message

• Bushel weight is easily measured and commonly used to place a relative market value on barley samples.
• Heavier barley has higher starch and lower fibre levels that lighter barley.
• Average daily gain of cattle fed barley based finishing diets is not affected by bushel weight.
• Feed: gain ratios are moderately affected by bushel weight.
• Based on differences in feed:gain ratios, barley economic value can be discounted approximately 1% for each pound of bushel weight below the normal 48 pounds/bushel. Canada No. 1 Feed is 48 pounds/bushel (59 kg/hL).
• Grains of different bushel weight should be processed before mixing to ensure uniform processing.

Barley has been grown by man since 3,000 BC and is the grain most often fed to growing and finishing beef cattle in Alberta. Moisture content, dockage and bushel weight are commonly measured and used to calculate economic value when barley is bought or sold.

Terminology

Bushel weight or the number of pounds per bushel volume is an imperial measure. The metric equivalent of bushel weight is called volume weight and the units are kilograms per hectolitre (kg/hL). To convert from pounds/bushel to kg/hL multiply by 1.25. Other terms that are used interchangeably with bushel or volume weight are test weight and bulk density. Weight per 1,000 grain kernels, sometimes seen in research reports, is not the same as bushel weight.

Factors Affecting Bushel Weight

Conditions during growing and harvesting affect the bushel weight of barley. These conditions include drought, frost before maturity and sprouting in the swath. There are also differences in bushel weight between barley varieties and types. Two row types are generally heavier than the six row types of barley.

Bushel weight is related to the amount of starch in barley grain; generally the greater the bushel weight the greater the starch content. The relationship between bushel weight and the various fibre components is negative; the higher the fibre the lower the bushel weight.

Digestible Energy and Bushel Weight

Digestion studies with ruminants (e.g. cattle, sheep) and monogastrics (e.g. hogs, poultry) have not shown a consistent relationship between bushel weight and digestible energy content. This is not surprising since it is difficult to conduct research trials where bushel weight is the only variable. Other factors such as variety, degree of grain processing, protein and fibre content, feed intake and foreign material content can all have an impact on digestion efficiency. Table 1 shows the results of a trial in which bushel weight varied by 153 % from lowest to highest, but the impact on digestibility of dry matter and digestible energy content was less than 5.8%. While the heavier three barleys were more digestible than the lightest one, there were no significant differences in the digestible energy values.

Table 1. Effect of Bushel Weight on Digestibility and Energy Value.

	Bushel Weight (pounds/bushel)
	34.4	47.2	51.2	52.8
Digestible Dry Matter (%)	78.3b	80.3a	82.0a	80.1a
Digestible Energy (Mcal/kg)	3.00	3.03	3.12	3.02

From Mathison et al. (2). Intake level was 1.6% to 1.7% of body wieght. The three lightest barleys were of the same variety grown in the same area of Alberta.

Bushel Weight And Cattle Performance in the Feedlot

During the 1980's three finishing trials were conducted in Alberta utilizing dry and steam rolled barley of different bushel weights. The results show that bushel weight does not affect average daily gain in finishing cattle (Table 2). Daily gain is not affected because, on high energy finishing rations, gut fill is not a limiting factor. Cattle can consume slightly more pounds of a low bushel weight barley to meet their need for energy. There does appear to be a moderate effect on feed:gain ratio when the weight of barley is below 48 pounds per bushel, the standard set for No. 1 Feed Barley by the Canada Grain Act, 1970.

Averaging the results of the first two studies (Table 2) indicates that feed:gain ratio is reduced by about 1.0% for each pound of bushel weight below 47 pounds. Thus, loss in feed efficiency is one factor to consider when placing a value on light weight barley. However, the results of all three trials show no significant improvement in feed:gain ratios for heavy bushel weight barleys, so a premium is not justified.

Processing Barley of Various Bushel Weights

In the three trials summarized in Table 2, the method of processing the barley (dry versus steam rolling) had no effect on feedlot cattle performance regardless of the bushel weights. However, the feedlot manager should pay close attention to the quality of processing when grains of varying bushel weights are used. Bushel weight is related to kernel plumpness and lighter weight barley will not be processed to the same extent as heavier barley with same roller settings. For this reason grains of different bushel weight should be processed before mixing with other grains rather than after. For a thorough discussion of processing, see Processing Feed Grains.

Table 2. Summary of Three Alberta Feedlot Trials.

Bushel Weight (pounds/bushel)	Average Daily Gain (kg)	Feed:Gain Ratio
Grimson et al. (1) - 192 yearling steers, 85% barley in finishing ration
37.8	1.62	5.80b
44.4	1.72	5.32a
53.3	1.69	5.26a
Mathison et al. (2) - 90 yearling steers, 81.6% barley in finishing ration
34.4	1.63	6.29
47.2	1.67	5.89
51.2	1.65	6.00
Engstrom et al. (3) - 120 yearling steers, 81.8% barley in finishing ration
45.5	1.57	6.12
47.1	1.49	6.35
47.6	1.55	6.34
53.0	1.53	5.97
53.8	1.56	5.85
56.4	1.56	5.92

Discounting Low Bushel Weight Barley

Reduced feed efficiency and increased management of processing have been discussed as factors that make discounting low bushel weight necessary. Other factors to be considered include increased trucking, storage, and feed delivery costs due to a the reduced capacity of equipment handling low bushel weight barley. Individual operators may have other reasons for additional discounts that are specific to their own feedlot. The format in Table 3 can be used to compare the discounts for barley of various bushel weights.

Table 3. Discounting Barley for Low Bushel Weight.

	Discounts (%)
Bushel Weight lbs/bus	Feed Efficiency	+	Inconvenience	=	Total
47	0.0	+		=
46	1.0	+		=
45	2.0	+		=
44	3.0	+		=
43	4.0	+		=
42	5.0	+		=
41	6.0	+		=
40	7.0	+		=
39	8.0	+		=
38	9.0	+		=
37	10.0	+		=
36	11.0	+		=

.
References

1. R.E Grimson et al. 1987. Effects of barley volume-weight and processing method on feedlot performance of finishing steers. Canadian Journal of Animal Science 67:43-53.
2. G. W. Mathison et al. 1991. Rate of starch degradation, apparent digestibility and rate and efficiency of steer gain as influenced by barley grain volumeweight and processing method. Canadian Journal of Animal Science 71:867-878.
3. D.F. Engstrom et al. 1991. Effect of beta-glucan, starch, and fibre content and steam vs. dry rolling of barley grain on its degradability and utilisation by steers. Animal Feed Science and Technology 37:33-46.