Beta-glucan Depleted Barley and Oat Flours as Animal Feed

Background

A vital connection exists between the crops and livestock components of agriculture. In Alberta, livestock producers select their grain source for feed based on the cost of the grain and its method of processing, the primary goal of which is to increase energy availability (Owens et al. 1997). The combination of lower price and limitations of climate and soil fertility that impede corn production (Boss & Bowman, 1996) makes barley an economically attractive feed. As a result, barley is used primarily as an energy and protein source in cattle diets and is one of the primary feed ingredients used by the swine industry. Barley varieties are generally plentiful crops and are therefore readily available at a reasonable cost. However, these grains contain relatively high proportions of non-starch polysaccharides (NSPS), especially beta-glucans (~4-7%), which are known for their anti-nutritive properties. In poultry, for example, endogenous enzymes have a limited ability to digest non-starch polysaccharides. Thus their content and composition in the diet can impart significant differences in biological responses and thus influence poultry productivity (Campbell et al. 1989). To control this anti-nutritive effect, enzymes that hydrolyze non-starch polysaccharides are often added to feeds and thus enhance the overall digestibility. Livestock producers generally select varieties low in beta-glucans in an attempt to control for these anti-nutritive properties.

A novel grain fractionation technology has been developed at the Dept. of Agricultural, Food and Nutritional Science, University of Alberta to isolate/concentrate beta-glucan from oat and barley grains in a cost-efficient manner. The technology is patented and now licensed to Cevena Bioproducts Inc., Edmonton, Alberta. Flours produced from these grains undergo alcohol based enzymatic process for beta-glucan isolation/concentration. The beta-glucan concentrate (Viscofiber®) is now commercially available for use in functional food and dietary supplements due to its valuable physiological properties (For more information go to: www.cevena.com). Two major byproducts of the process are crude starch and a blend of hydrolyzed starch and protein mixture. These components are the most valuable by-products of the technology and comprise the largest volume (~80% and ~5%, w/w, respectively) of the raw material weight. While, whole or minimally processed (i.e. flaked) barley and oat grains have been traditionally used in animal feeds, the nutritional value of the aforementioned by-products that are depleted in anti-nutritional factors (i.e. beta-glucan) is not known.

Overall Goals and Objectives

The overall goal of this research project is to evaluate the potential of beta-glucan depleted barley/oat flour (i.e. crude starch) for use in the diets of livestock animals in order to determine their digestible nutrient content and optimal level of inclusion and thereby to provide evidence for inclusion of these byproducts in livestock production. Diets formulated with these ingredients will be compared to commercial feeds. Development of novel applications for these by-products is important to ensure that the grains are completely utilized and this is critical for the overall commercial success of this technology. Furthermore, since barley and oats are established natural feed crops, utilization of the aforementioned byproducts in feeds would be safe and would not pose any threat to food security. It is also important to note that this research has potential to doubly benefit the agriculture industry, not only by enhancing cereal production and processing, but also by improving livestock production.

Results

Evaluation of the use of beta-glucan depleted barley/oat flour as natural feed ingredient in young Holstein calves
The objective of the first trial conducted in young Holstein calves was to compare the nutritional value of barley and oat starch isolate by-products to a commercial calf grower diet. Calves (n=27, approximately 2-4 months of age, average initial weight: 110 kg ± 3) were randomly allocated to one of three treatment diets (3 calves/diet/pen) and fed ad libitum using Cailan gates. Three diets were formulated as specified by the National Research Council (NRC 2000) and contained 25% oat starch (oat starch diet) and 25% barley starch (barley starch diet). In order to allow an appropriate comparison between the commercial and starch test diets, all diets were made isonitrogenous (18% crude protein) and similar in energy content (MCal; Standard – 1.21, Oat – 1.33, Barley – 1.33), which was verified by proximate analysis. Following feed acclimatization and training on the Cailan gate system (approx. 3 weeks), calves were healthy, consumed adequate feed and grew well for the remainder of the trial. On average, calves supplemented for five weeks gained 52 ± 1 kg and had an average final BW of 189 ± 4 kg. Feed intake (FI) averaged 4.95 ± 0.20 kg/d. Despite initial concerns that the high amount of starch in the oat and barley diets would influence calf feed intake, and thus performance, there was no significant effect of diet on any of the recorded performance measures in this study (Table 1). A sub-group of calves that were fed Chromium-mordanted fiber underwent periodic feces collection (4 hours for two days, then at 54, 60, 72 and 96 hours). The appearance of Chromium in feces, and thus the rate of passage of each diet was similar, peaking between 16 and 36 hours and reaching negligible levels by 96 hours. Therefore, based on the results from this initial study, a high proportion (up to 25%) of both oat- and barley-derived starch products can be included in the diets of young calves as an ideal energy source.

Table 1. Body weight and feed intake of calves

Dietary Group	Standard (g/kg)	Oat Crude Starch (g/kg)	Barley Crude Starch (g/kg)
Initial BW, g	136 ± 71,2	136 ± 5	138 ± 6
Final BW, g	192 ± 8	187 ± 7	190 ± 7
Average Gain, g	56 ± 2	50 ± 3	51 ± 2
Average FI, g/d	5.0 ± 0.53	5.1 ± 0.28	4.7 ± 0.13

¹ Values presented as mean ± SEM.
² There were no significant differences (p<0.05) in any performance measure.

Evaluation of the use of beta-glucan-depleted barley and oat flour as a natural ingredient for chickens
The objective of this trial was to evaluate the digestible nutrient content of beta-glucan depleted barley flour (i.e. crude starch) in the diets of broiler chickens. Since the endogenous enzymes of poultry cannot digest non-starch polysaccharides, the ability of enzyme (Avizyme® 1102; Danisco Animal Nutrition) to hydrolyze beta-glucans and thus enhance the overall digestibility was also examined in this study. Broiler chickens were fed isonitrogenous, isoenergetic diets between 0 and 42 d of age. For each growth period (starter 0-10 d, grower 11-28 d and finisher 29-42 d), a total of 5 diets were formulated according to NRC requirements (NRC 1994), which was confirmed by proximate analysis. Diets included a corn basal diet (#1), a barley flour based diet with (#2) and without (#3) added enzyme, and a barley crude starch-based diet with (#4) and without (#5) added enzyme. The major ingredient (i.e. barley flour, crude starch, etc) in each diet made up approximately 50% of the total diet. Chicks (n=602) were obtained at 1 d of age (initial weight: 44.3 g) and randomly assigned to 1 of 72 pens (8 pens/treatment). Body weight was measured on days 0, 10, 28 and 42. Average daily gain, feed intake and feed conversion efficiency were also determined between 0-10, 11-28 and 29-42 days.

Results of the study (Table 2) revealed that chickens consuming corn-based diets had a significantly higher average body weight, average daily gain and feed intake throughout the course of the trial. In contrast, with the exception of initial values, birds consuming barley flour-based diet had the lowest average body weight compared to all other dietary treatments. Barley-fed chickens had lower average daily gain, but higher feed conversion efficiency for the duration of the trial, which was also reflected at all time points. However, addition of enzyme to barley diets significantly improved average body weight and average daily gain at all time points. Chickens fed with barley crude starch diets were found to have many similar performance parameters to those chickens fed with enzyme-supplemented barley diets.

The poor performance of barley flour-fed chickens may be attributed to the high viscosity and texture of diets containing barley. The high beta-glucan content of barley flour would have substantially increased intestinal viscosity and may have interfered with digestion. In addition, beta-glucan has satiety factors, which may have influenced the amount of feed that chickens in this group were compelled to consume. Alternatively, barley-containing diets had a tendency to stick together within feeders, which may have interfered with the birds’ consumption ability (i.e. feed intake). Therefore, an alternate type of feed processing, such as pelleting, may have minimized some of the observed problems in feed handing and feed flow and may improve feed intake. Since feed conversion efficiency was highest in barley-fed chickens, an improvement in feed intake would likely cause increased weight gain. It should also be noted that high inclusion levels (~50%) of the major ingredient were used in this study. Future studies are warranted to determine if performance would differ with different levels of inclusion. Results of this trial confirmed the ability of enzyme supplementation to enhance digestibility, a trend most pronounced in chickens fed barley-based diets. In addition to hydrolyzing non-starch polysaccharides, the enzyme used in this study would have also decreased intestinal viscosity. This would explain the observed increased performance of chicks fed barley-based diets with enzyme. It is important to highlight the fact that chickens fed with barley crude starch diets had generally equal performance to enzyme-supplemented broilers. This finding reinforces the great potential of this byproduct in livestock formulations to cut down on costs incurred from enzyme supplementation, without suffering any detriment to broiler performance.

Table 2. Performance measures of chickens fed diets differing in major grain

Ingredient	#1 – Corn	#2 – Barley flour	#3 – Barley flour + enzyme	#4 - Barley Crude Starch	#5 - Barley Crude Starch + enzyme
ABW1 (g)
D0	43.82 ± 0.44	44.5 ± 0.48	44.7 ± 0.39	44.7 ± 0.40	44.3 ± 0.48
D10	231.5 ± 5.43a3	147.2 ± 3.98d	176.3 ± 5.50c	202.3 ± 8.01b	186.3 ± 3.32c
D28	1110.3 ± 33.53a	650.6 ± 26.33c	794.3 ± 26.04b	825.2 ± 31.93b	850.5 ± 18.44b
D42	2394.2 ± 33.70a	1369.9 ± 46.86c	1709.1 ± 64.02b	1714.5 ± 50.50b	1809.8 ± 73.11b
ADG4 (g/d)
D0-10	19.7 ± 0.54a	10.8 ± 0.38d	13.6 ± 0.59c	16.4 ± 0.80b	14.8 ± 0.30c
D11-28	51.7 ± 1.89a	29.6 ± 1.34c	36.3 ± 1.35b	36.4 ± 1.88b	38.0 ± 1.16b
D29-42	99.9 ± 2.16a	55.8 ± 2.21c	67.4 ± 3.22b	69.9 ± 2.33b	72.7 ± 4.56b
D1-42	54.8 ± 0.65a	30.7 ± 0.99c	37.5 ± 1.68b	39.1 ± 1.17b	38.6 ± 1.34b
FI5 (g/bird/d)
D0-10	25.0 ± 0.47a	20.8 ± 0.84b	22.0 ± 0.96b	22.0 ± 1.22b	21.4 ± 0.33b
D11-28	83.3 ± 2.66	81.6 ± 4.93	79.3 ± 3.70	75.9 ± 1.67	84.5 ± 3.00
D29-42	173.3 ± 3.87a	134.5 ± 10.61b	137.9 ± 8.24b	129.3 ± 3.89c	152.5 ± 9.92a
D1-42	89.7 ± 1.02a	76.6 ± 4.16b	76.4 ± 3.48b	73.4 ± 0.81b	79.5 ± 2.33b
FCE6
D0-10	1.27 ± 0.03d	1.94 ± 0.12a	1.62 ± 0.07b	1.36 ± 0.08cd	1.46 ± 0.05bc
D11-28	1.61 ± 0.03c	2.79 ± 0.19a	2.18 ± 0.07b	2.13 ± 0.13b	2.24 ± 0.11b
D29-42	1.74 ± 0.02b	2.40 ± 0.12a	2.08 ± 0.15ab	1.86 ± 0.07b	2.12 ± 0.10ab
D1-42	1.64 ± 0.01c	2.50 ± 0.12a	2.05 ± 0.08b	1.89 ± 0.06b	2.07 ± 0.07b

¹ Average Body Weight
² Values presented as mean ± SEM
³ Within a row, means without a common superscript letter differ (P < 0.05)
⁴ Average Daily Gain
⁵ Feed Intake
⁶ Feed Conversion Efficiency


Future Direction and Conclusion

At this stage of the research project, the nutritional value of barley crude starch diets has been determined in young calves and the digestible nutrient content has been determined in broilers. The next phase of the research project is on the verge of beginning. The objective of this trial is to relatively evaluate the digestible nutrient content of barley crude starch in growing pigs. Digestibility will be assessed by fitting 8 pigs with ileal T-cannulas, followed by collection of ileal digesta samples. Results from this trial will be compared to the previous study in poultry, as digestibility of these products is expected to differ. Once the digestible nutrient content of these products has been determined, it will be possible to proceed with more detailed studies. These will include livestock production trials that will utilize these products in nutritionally complete diets that have also been formulated from an economical perspective, thus allowing these diets to be manufactured and purchased at a reasonable cost. There are also trials being planned to extend the results of previous studies and answer some of the questions these trials have presented. It is still unclear if the texture and form of the diets may have influenced the results of this pilot study. It would be necessary to evaluate if chickens would respond differently, especially in terms of feed intake and weight gain, to a product that undergoes cold pelleting and then crumbling. An additional component of this feed research project currently being planned is the use of the high-quality hydrolyzed protein and starch blend from oat and barley that are produced along with the crude starch products. In conclusion, studies conducted thus far indicate that barley- and oat-derived products have great potential as valuable and cost effective feed ingredients.

References

1. Boss, D.L., and Bowman, J.G.P. 1996. Barley varieties for finishing steers: I. Feedlot performance, in vivo diet digestion, and carcass characteristics. J. Anim. Sci. 74(8): 1967.
2. Campbell, G.L., Rossnagel, B.G., Classen, H.L., and Thacker, P.A. 1989. Genotypic and environmental differences in extract viscosity of barley and their relationship to its nutritive value for broiler chickens. Ani. Feed Sci. Tech. 226: 221.
3. NRC. 1994. Nutrient Requirements of Poultry (9th Ed.). Subcom. Poultry Nutr., Comm Anim. Nutr., Board Agric., NRC. Nat. Acad. Press, Wash. pp 157.
4. NRC. 2000. Nutrient Requirements of Beef Cattle (7th Ed. update). Subcom. Beef Cattle Nutr., Comm. Anim. Nutr., Board Agric., NRC. Nat. Acad. Press, Wash. pp 224.
5. Owens, F.N., Secrist, D.S., Hill, W.J., and Gill, D.R. 1997. The effect of grain source and grain processing on performance of feedlot cattle: a review. J. Anim. Sci. 75(3): 868.

Ian R. Johnson, Doug R. Korver*, Thava Vasanthan* and Feral Temelli
University of Alberta, Edmonton, Alberta, Canada
*Corresponding authors

Presented at the North American Barley Researchers Workshop, July 17-20, 2005