Assessment of Hull-less Barley as a Locally Grown Swine Feed Ingredient in the Mid-Atlantic Region of the United States1

Professional Animal Scientist, Dec 2004 by Harper, A F, Radcliffe, J S, Estienne, M J

Abstract

Crossbred pigs (six replicate pens of four pigs per treatment, avg. initial BW = 38 kg) were used in a 6-wk growth and digestibility trial to assess a hull-less barley adapted for the mid Atlantic region of the U.S. as the primary ingredient in pelleted diets for growing pigs. There were five experimental diets: 1) a corn-soybean meal-based diet, 2) a diet containing 46% hull-less barley and 1.6% added fat, 3) a diet containing 41% hulled barley and 4.1% added fat, 4) a diet containing 46% hulled barley and 1.6% added fat, and 5) a diet containing 46% wheat and 0.68% added fat. For diets based on small grains, a fixed inclusion rate of 25% corn was used. With the exception of Diet 4, all diets were formulated to be iso-lysinic and iso-caloric. Diet type had no effect (P>0.10) on ADFI or ADG. Pigs fed the hulled barley, high-fat diet (Diet 3) had slightly improved feed efficiency (P

(Key Words: Feed Ingredient, Hull-less Barley, Pigs.)

Introduction

The mid-Atlantic region of the U.S. has substantial poultry and swine production, but grain production in the region is limited and has declined in recent years (USDA-NASS, 2003). Consequently, the mid-Atlantic region is a grain-deficit area with significant quantities of corn and other grains being imported to support swine and poultry production. Barley represents a feed grain that is grown in substantial quantities in the northwestern U.S. and western provinces of Canada. Production of barley in the mid-Atlantic region of the U.S. is limited, but crop scientists have demonstrated that this grain has good yield potential in the area (Anonymous, 1994; Paris, 2000). As a winter annual that can be harvested earlier than most wheat varieties, barley performs well in double-cropping systems with summer annual crops such as soybeans. Despite these agronomic advantages, there are limitations for barley as a feed grain for nonruminants. The fibrous seed coat or hull of most commercial barley varieties is cemented to the caryopsis and is not removed during threshing. This fibrous hull reduces grain density and makes barley a high-fiber, lower-energy feed ingredient relative to corn and wheat. Fairbairn et al. (1999) reported that grain density characteristics and fiber content accounts for >85% of the variation in digestible energy among barley cultivars. Development of hull-less barley varieties began in the provinces of western Canada and northern plain states in the late 1960s. A limited number of experiments indicated that hull-less barleys were 8 to 14% greater in digestible energy than traditional barley and up to 7% greater in protein digestibility (Bhatty et al., 1979; Aherne, 1990). In 1996, crop scientists at Virginia Polytechnic Institute and State University (VPI) began a breeding and evaluation program to develop hull-less barley cultivars adapted to the mid-Atlantic growing region. The objective of this study was to assess a line of hull-less barley developed from the VPI breeding program as a major feed ingredient in growing pig diets based on growth performance and nutrient digestibility. For comparison purposes, diets based primarily on corn, hulled barley, and wheat were also assessed.

Materials and Methods

Test Grains. The hull-less barley was grown and harvested at the Virginia Crop Improvement Association Foundation Seed Farm at Mount Holly, VA. The hulled barley variety used was Callao and was harvested on a commercial farm near the foundation seed farm. Soft red winter wheat and corn used were produced on farms in southeast Virginia and obtained from a local grain dealer. Prior to formulation of experimental diets, samples of each grain type and de-hulled soybean meal were analyzed at the VPI swine nutrition laboratory for DM, Ca, and P, and by the Experiment Station Chemical Laboratories at the University of Missouri-Columbia for amino acid content (Table 1). As a precaution, all four test grains and the soybean meal used in the experiment were screen tested using ELISA for the presence of aflatoxins, zearalenone, and vomitoxin. No mycotoxins were detected.

Dietary Treatments. Experimental diets were formulated using the assayed amino acid and mineral levels to simulate commercial-type diets for grower pigs. Reference values (NRC, 1998) were used to calculate digestible energy content. Diets based on barley or wheat contained a fixed level of 25% corn. Dehulled soybean meal was added to all diets to balance amino acid requirements, and rendered poultry fat was added to adjust energy content where appropriate (Table 2). The five dietary treatments included: 1) a corn-soybean meal-based diet with no small grain, 2) a diet containing 46% hull-less barley and 1.6% added fat, 3) a diet containing 41% Callao hulled barley and 4.1% added fat, 4) a diet containing 46% Callao hulled barley and 1.6% added fat, and 5) a diet containing 46% wheat and 0.68% added fat. With the exception of Diet 4, all diets were calculated to contain 0.95% lysine, 0.60% Ca, 0.23% available P, and 3446 kcal/kg of digestible energy. Diet 4, in which hulled barley replaced the hull-less barley in Diet 2 on an equal weight basis, was calculated to contain 0.91% lysine, 0.60% Ca, 0.22% available P, and 3302 kcal/kg of digestible energy. All diets contained an antioxidant (0.013%; Santoquin�; Novus International, St. Louis, MO), a mold inhibitor (0.1%; Myco-Curb�; Kemin Industries, Des Moines, IA), a pellet binding agent (1.25%; Ameri-Bond 2X�; Lignotech Inc., Rothschild, WI), and 0.2% of a Cr^sub 2^O^sub 3^-COm starch (1:3, wt:wt) premix to allow for calculation of digestion coefficients (Table 2).

Prior to diet preparation, corn was ground to pass through a 4.76-mm screen using a hammermill, and hull-less barley, Callao barley, and wheat were ground to pass through a 3.18-mm screen. Because of unique size and shape of kernels from each grain type, these specific screen sizes were used to achieve desired particle sizes in the ground grains. Duplicate samples of each ground grain type were tested for particle size at the Kansas State University, Department of Grain Science and Industry Feed Grains Laboratory, Manhattan, KS. Mean particle sizes were 873, 914, 879, and 559 � for the ground corn, hull-less barley, Callao barley, and wheat, respectively.

After grinding, experimental diets were blended and mixed in 2722-kg batches according to the diet formulations in Table 2. Bagged feed was transported to a commercial feed mill (Keystone Milling Company, South Boston, VA) and processed using a commercial pellet mill into 5.16-mm pellets. The feeds were then re-bagged into labeled paper bags in 25-kg quantities and transported back to the VPI Tidewater Agricultural Research and Extension Center Swine Unit, Suffolk, VA for the experiment.

Experimental Animals. The animals used in the experiment were humanely cared for within published welfare guidelines (FASS, 1999). One hundred twenty crossbred pigs (Yorkshire � Landrace, equal number of barrows and gilts) with an average initial BW of 38 � 0.10 kg were used in the 6-wk growth trial. There were six replicate pens of four pigs for each diet. Pigs were blocked by BW, sex, and ancestry and randomly assigned to pens and diets within block. Pens (5.1 m^sup 2^) were located in a mechanically ventilated swine barn, equipped with partially slatted concrete floors, a two-hole stainless steel feeder, and a nipple waterer in each pen. Pigs had ad libitum access to feed and water. Individual pig weights and total pen feed consumption were determined weekly.