Animal Feed Science and Technology 137 (2007) 1–24

Review

Effects of barley grain processing on productivity of cattle M. Dehghan-banadaky a , R. Corbett b , M. Oba a,∗ a

b

Department of Agriculture, Food and Nutritional Sciences, University of Alberta, Edmonton, Alta. T6G 2P5, Canada Alberta Agriculture, Food and Rural Development, Edmonton, Alta. T6H 5T6, Canada

Received 16 August 2006; received in revised form 12 November 2006; accepted 21 November 2006

Abstract Barley grain is one of the most common feed grains used in diets for dairy and beef cattle. Because the endosperm of the barley kernel is surrounded by the pericarp, which is extremely resistant to microbial degradation in the rumen, dry barley grain needs to be processed to improve its utilization by beef and dairy cattle. Dry rolling is a common processing method, and increases ruminal digestibility of grain and productivity of animals, but the grain kernels often shatter during processing, producing many fine particles, which has been associated with inconsistent animal performance. Steam rolling and temper rolling can reduce production of fine particles during rolling, allowing more uniform particle size distribution. Steam flaking uses moisture, heat and pressure to gelatinize starch granules, but positive effects of starch gelatinization on animal performance may be less for barley grain versus corn or sorghum because barley starch, once exposed to microbial organisms in the rumen, is readily degradable even without being gelatinized. Treatment of grains with NaOH may increase its ruminal starch digestibility without increasing ruminal rate of starch release. Roasting and aldehyde treatment decrease the rate of crude protein degradation and optimize organic matter degradation in the rumen, while application of ammonia or fibrolytic enzymes can increase degradation of the hull. Consistency in processed grain quality (e.g., particle size) and predictability in animal performance should be considered as an important quality parameter of processing. In addition, initial grain quality, extent of processing, processing method, and their interactions, determine the feeding value of barley grain and

Abbreviations: ADG, average daily gain; ADF, acid detergent fiber; CP, crude protein; DM, dry matter; DMI, dry matter intake; FE, feed efficiency; NDF, neutral detergent fiber; OM, organic matter; PI, processing index ∗ Corresponding author. Tel.: +1 780 492 7007; fax: +1 780 492 4265. E-mail address: [email protected] (M. Oba). 0377-8401/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.anifeedsci.2006.11.021

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affect the productivity of cattle. Further research is warranted to develop a common quality parameter accounting for variations in physical, chemical and biochemical properties for processed barley grain. © 2006 Elsevier B.V. All rights reserved. Keywords: Barley grain; Processing; Dairy cows; Beef cattle; Productivity

Contents 1. 2.

3.

4.

5. 6.

7.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cold physical processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1. Grinding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2. Dry rolling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3. Tempering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hot physical processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Steam rolling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Steam flaking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3. Pelleting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4. Roasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5. Other hot physical processing methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. Sodium hydroxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Ammonia/urea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. Aldehydes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4. Other chemical processing methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Enzymatic processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Factors affecting animal responses to barley grain processing . . . . . . . . . . . . . . . . . . . . . . . . 6.1. Extent of processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2. Quality of barley grain before processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 3 3 3 4 6 8 10 11 12 12 13 13 14 14 15 15 16 16 19 19 20

1. Introduction Barley is an important feed grain for ruminant livestock species in many areas of the world as it is a readily available source of dietary energy. However, the endosperm of the barley kernel is surrounded by the pericarp which is overlain by a fibrous hull, which is extremely resistant to microbial degradation in the rumen. Processing makes the starch more accessible to microbes, and increases the rate and extent of starch degradation in the rumen. Although processing is essential to maximize the utilization of barley grain by cattle, extensive grain processing increases ruminal starch degradation, which often decreases feed intake in ruminants (Allen, 2000). Optimum alteration of the site of starch digestion requires processing methods or conditions that increase starch flow to the duodenum without reducing its total tract digestibility. Additional glucose absorption at the duode-

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num may reduce gluconeogenesis and increase productivity of ruminants (Kassem et al., 1987). Processing methods of barley grain and their effects on productivity of ruminants have been reviewed (Hunt, 1996; Mathison, 1996). However, recent research that evaluated unique processing methods using chemicals or enzymes was not covered. In addition, the extent to which processing of barley grain improves productivity of ruminants is variable. Thus, our objectives of this review are to provide a comprehensive review of publications on physical, chemical, and enzymatic processing of barley grain on productivity of growing beef cattle and lactating dairy cows, and to evaluate factors affecting animal responses to barley grain processing.

2. Cold physical processing Physical processing, such as rolling and grinding, breaks the physical barrier of hull and pericarp, thereby allowing access of rumen microorganisms and digestive enzymes to the nutrient rich endosperm. In cold physical processing, a hammer mill or roller mill is used to decrease particle size and increase surface area of grain without application of heat or steam. Beauchemin et al. (1994) demonstrated that whole barley is largely indigestible, and the masticated barley kernels (i.e., chewed once) are more digestible than intact kernels, but halving or quartering the kernels improved in situ dry matter (DM) disappearance even more than chewing. Tempering, in which moisture is added to the grain, maintains particle size of grain by reducing its shattering, and often reduces rate of starch degradation compared with dry rolling or grinding. 2.1. Grinding Grinding with a hammer mill is a simple process to reduce the particle size of grains. Grinding fractures the outer layers of grain exposing more of the endosperm to degradation (Hoseney, 1994). Grinding also greatly increases the surface area available for microbial attachment, and rate of starch degradation in the rumen varies inversely with particle size of the grain (Galyean et al., 1981). Finely ground barley grain ferments more rapidly than cracked barley grain, and may reduce productivity of cattle. Mathison (1996) reported that steers fed ground barley in an all concentrate diet gained 0.09 kg/d less body weight with reduced feed efficiency (FE) compared with those fed rolled barley. Moreover, steers fed ground barley had 0.15 cm less back fat. These reductions in performance were attributed to a 5% reduction in feed intake for steers fed ground barley versus those fed rolled barley. 2.2. Dry rolling Dry rolling is achieved by passing grain kernels between rotating rollers to break the pericarp and expose the endosperm to microbial degradation in the rumen. Roller mills provide a more uniform particle size distribution, producing fewer fine particles than grinding. Dry rolling improved the whole tract organic matter (OM) digestibility of barley from 525 to 852 g/kg compared to whole grain in beef steers (Tolland, 1976), and 482 g/kg of whole

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kernels were recovered in the feces, indicating that cattle have difficulty digesting unprocessed barley kernels. Similarly, Ørskov et al. (1978) reported whole tract DM digestibility of 672 g/kg for whole barley and 834 g/kg for dry rolled barley. Rolled barley fed to beef steers had higher whole tract DM digestibility than whole barley (Mathison et al., 1991a), which was associated with an improvement in FE (6.28 versus 7.25; dry matter intake (DMI)/gain) for rolled versus whole barley. Economides et al. (1990) also reported improved FE in finishing cattle fed dry rolled barley versus whole barley, although average daily gain (ADG) was not affected. In the study of Goonewardene et al. (1998), steers fed rolled high moisture barley had improved ADG of 9.1% and FE of 13.1%, compared to cattle fed whole high moisture barley, although DMI was not affected. Other studies also showed that rolled barley improved growth rate and FE in beef cattle versus whole barley (Yaremcio et al., 1991; Mathison et al., 1991a). The improved performance can be attributed to the higher whole tract digestibility of rolled barley (Nicholson et al., 1971; Mathison et al., 1991a). 2.3. Tempering Tempering is achieved by raising the moisture content of the barley to 200–250 g/kg by adding water, mixing, and storing for 12–24 h prior to rolling. Advantages of tempering include reduced dustiness and production of fewer fine particles during rolling, but require corrosion resistant bins for soaking the grain. Tempering restores moisture to the kernel before rolling, which helps maintain the integrity of the kernel and reduces shattering as the kernels pass between the rollers (Yang et al., 1996). Tempering increases the proportion of particles retained on the coarsest screens while decreasing the particles on the finer screens (Table 1; Combs and Hinman, 1989; Wang et al., 2003). Mathison et al. (1997) observed fewer coarse, and more fine, particles only in the most extensively processed dry rolled treatment compared with extensively processed tempered grain. In their study, the barley used in the dry treatments contained 140 g moisture/kg, which may have been adequate for preventing production of fine particles in the less extensively (i.e., slight and medium) processed grain. Hinman and Sorenson (1994) investigated effects of duration of tempering. Barley was cold tempered to 160 g moisture/kg and rolled at 0, 6, 12 or 24 h following tempering. They reported higher steer ADG with no differences in FE when barley was allowed to temper for 12 h prior to processing. Wang et al. (2003) suggested that effects of tempering on animal performance are affected by roller setting, moisture content of the whole grain, and composition of the diet. The DMI, ADG and FE were not affected when tempered rolled grain was fed to growing cattle (Table 2; Bradshaw et al., 1996; Wang et al., 2003). However, Bradshaw et al. (1996) reported a 5.4, 5.7 and 14.2% improvement in whole tract DM digestibility, gross energy digestibility and barley digestible energy content, respectively, in favor of the tempered barley. Wang et al. (2003; Table 3) found a 45% reduction in rate of ruminal DM degradation of coarsely rolled tempered barley and 33% reduction when the grain was more extensively rolled compared to barley dry rolled using the same roller settings. Yang et al. (1996) reported a similar reduction (33.6%) in ruminal DM degradation rate for tempered barley. Hinman and Combs (1984) reported improvements in DMI (4.3%) and ADG (12.1%) with a numerical improvement in feed conversion efficiency (9.0%) in favor of tempered grain.

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Table 1 Effect of dry vs. temper rolling on particle size distribution Dry rolled Mathison et al. (1997) PIa 94 a 92 a 83 b Percentage retained on each screen with specified pore size 2.38 mm 90.5 a 85.1 a 61.2 b 2.00 mm 1.9 b 3.3 b 10.2 a 0.841 mm 2.0 b 4.1 b 16.3 a 0.594 mm 1.3 b 2.0 b 4.1 a 0.297 mm 1.5 b 2.1 ab 3.5 a Combs and Hinman (1989) PI 68 Percentage retained on each screen with specified pore size 4.75 mm 0.84 2.00 mm 71.68 1.00 mm 19.75 0.50 mm 6.32 0.25 mm 1.12 0.125 mm 0.25 Pan 0.03 Wang et al. (2003) PI 81 a 67 b Percentage retained on each screen with specified pore size 4.75 mm 0.28 a 0.75 a 3.35 mm 37.62 a 32.74 a 2.36 mm 39.35 a 34.66 ab 1.70 mm 14.35 a 20.2 b Pan 8.37 a 11.58 a

Temper rolled 83 b

84 b

73 c

93.8 a 1.7 b 1.5 b 1.0 b 0.7 b

87.3 a 2.4 b 3.3 b 2.2 b 1.9 b

82.3 a 3.8 b 4.6 b 2.6 b 2.3 ab

72 22.32 76.07 1.16 0.24 0.12 0.03 0.02 79 a

71 b

2.66 b 61.81 b 29.91 b 3.16 c 2.42 b

5.69 c 62.51 b 23.79 c 5.01 c 2.96 b

Means within a row followed by different letters (a–c) differ (P