ENERGY CONTENT OF BARLEY VARIATION IN THE DIETARY ENERGY CONTENT OF BARLEY Shwn Firbirn, John Ptience, Hnk Clssen nd Ruurd Zijlstr SUMMARY Formultion of commercil pig diets requires n incresing degree of precision, in order to minimize the cost of production, optimize performnce nd chieve the highest qulity of crcss possible. Such precision, while necessry, is difficult to chieve, given the high degree of vrition in common feed ingredients. For exmple, the level of digestible energy in brley cn vry by s much s 8-12% or 250-370 kcl. Given tht nutritionists ttempt to formulte diets to within tolernce of 50 kcl/kg, the problem is pprent. This study ws conducted to identify the fctors, which cuse energy vrition in brley nd estblish system to estimte the digestible (DE) nd metbolizble energy (ME) levels in brley smples. Four smples of ech of five hulled brley vrieties were collected cross the three Pririe provinces nd fed to growing brrows to determine the pprent digestibility of energy nd severl other nutrients. The men DE nd ME vlues were 2,934 nd 2,857 kcl/kg (s fed bsis), respectively, with rnge in the order of 15%. Acid detergent fibre (ADF) ws the single most importnt vrible, explining 85% of the observed vrition in DE. Prediction equtions were developed to estimte the DE nd ME levels in brley. Economic nlysis determined the mrket vlue of the 20 brley smples vried by more thn $60/tonne, compred with n verge price of $110/tonne t the time of the study. INTRODUCTION Brley is mjor ingredient in commercil swine diets in mny prts of the world. Currently, brley is trded s commodity, with little effort to differentite smples bsed on ctul nutrient content. However, the economic vlue of brley could be incresed if the ctul energy content of individul smples could be ccurtely estimted or predicted. 40 This would include overcoming the uncertinty ssocited with vrition in DE nd ME tht hs been observed to be s high s 20% (c. 600 kcl/kg). Given tht nutritionists seek to formulte diets to within tolernce of 50 kcl/kg (c. 1.5%), the mgnitude of the problem is pprent. The problem is certinly not restricted to brley, s similr vrition is observed in most of bsl ingredients. This lck of precision rises feed costs, lowers production performnce, reduces crcss uniformity nd decreses the economic potentil of ny livestock opertion. A better understnding of the vrition in energy content of brley will improve the ccurcy of diet formultion, improve the profitbility of feeding pigs nd enhnce the economic vlue of brley to the pig industry. Benefits will ccrue to both the grins nd livestock industries. The objectives of this study were to chrcterize the sources of vribility in energy content nd to develop prcticl method to ccurtely estimte the digestible (DE) nd metbolizble (ME) energy content in individul brley smples. EXPERIMENTAL PROCEDURE A feed industry survey ws used to select hulled vrieties of brley to include in this experiment. Differences in feed vs. mlt, two- vs. six-row, nd importnce to the swine industry cross the Priries, were ll considered. Four smples of ech of the five vrieties (AC Lcombe, B-1602, Bedford, Hrrington, nd Mnley) were obtined from Albert, Mnitob nd Ssktchewn. The 20 smples were thus selected to obtin nutritionl nd regionl diversity. Fifty 35-kg brrows were plced in specil metbolism crtes to permit collection of urine nd feces, nd thus determine the ctul DE nd ME content of ech brley smple. Feed, fecl, nd urine smples were collected in order to determine DE nd ME. Feed nd fecl smples were lso used to determine pprent digestibility of protein (CP), lipids (EE), cid detergent fibre (ADF) nd neutrl detergent fibre (NDF). The brley smples were lso nlyzed for wide rnge of chemicl constituents such s strch, glucns, mino cids, nd severl different types of fibre. Sttisticl nlyses were conducted to derive prediction equtions which relted the energy content
in the brley to other more esily mesured qulity chrcteristics. RESULTS AND DISCUSSION There ws lrge vrition mong the twenty brley smples in physicl chrcteristics (Tble 1), nutrient digestibility (Tble 2) nd chemicl constituents (Tble 3). The men DE for the ll brley smples included in this experiment ws 2,934 kcl/kg (Tble 2). The DE rnged from 2,686 to 3,133 kcl/kg, difference of 447 kcl or 15.3%. Bushel weight rnged from 43.5 to 55.9 lb/bu. However, tht bushel weight lone ws not n ccurte mesure of energy content. For exmple, two brley smples which hd similr bushel weight (51 lb/bu) hd DE vlues which differed by 310 kcl (2,803-3,113 kcl/kg). Acid detergent fibre proved to be the single most ccurte predictor of DE content, explining 85% of the totl vrition in the energy content (Figure 1). For every 1% increse in ADF, DE declined by bout 90 kcl/kg. Prediction equtions to estimte DE or ME levels re presented in Tble 4. These equtions were developed to chieve desired level of ccurcy, but were lso creted to be prcticl nd economicl. The nlysis required for these equtions re not overly expensive nd cn usully be done quickly in most commercil lbortories. For exmple in Eqution 1 of Tble 4, if ADF, CP, nd 1000 kernel weight nlyses were conducted on prticulr brley smple nd if those vlues were substituted into the eqution, the resulting estimte of DE would be 88% ccurte. This would llow for more precise diet formultion once the energy level ws estimted compred with ssuming the brley contined the verge DE book vlue. The economic vlue of the twenty brley smples for industry typicl grower diet were clculted with July, 1997 prices for ingredients with the feed formultion softwre Brill, nd re reported in Tble 5. Vlue of the brley smples rnged from 78.12 to 139.39 $/1000 kg in grower diet, difference of $61.27 or 56%. IMPLICATIONS An improved understnding of, nd bility to estimte the energy vribility in brley, mkes it possible to more precisely formulte pig diets, voiding costly over-formultion while t the sme time ensuring minimum requirements re met. A prcticl method to ccurtely estimte energy content in brley will result in reduction in feed costs, improved crcss uniformity, bility to mrket brley on nutritionl vlue bsis, nd decresed mounts of wsted nutrients in the slurry. ACKNOWLEDGMENTS The uthors cknowledge the pork producers of Ssktchewn, Mnitob nd Albert for their strtegic funding to Pririe Swine Centre Inc. The reserchers would lso like to kindly thnk Deguss Corportion for mino cid nlysis nd Knss Stte University for prticle size nlysis. 41
Figure 1. Reltionship between digestible energy (90% DM) nd cid detergent fibre (90% DM). Tble 1. Physicl chrcteristics of the brley smples. Vriety Item AC-Lcombe B-1602 Bedford Hrrington Mnley Men Totl Avg. SD SD mong SD within vriety b vrieties c Bushel weight, lb/bu 48.5 50.5 48.9 49.8 51.6 49.9 3.44 3.561.24 Unclen bushel weight, lb/bu 47.2 48.9 48.8 48.0 49.5 48.5 4.35 4.64 0.86 Test weight, kg/hl 60.5 63.0 61.0 62.2 64.4 62.2 4.30 4.46 1.55 1000 Kernel weight, g 41.36 35.63 33.22 40.00 43.82 38.81 6.97 6.28 4.31 Dockge, % 0.5 0.8 0.9 2.8 1.5 1.3 1.52 1.18 0.92 1000 kernel volume, ml 35.0 29.6 30.1 33.2 37.2 33.0 4.80 4.16 3.25 Prticle size, µm 1330.93 d 982.92 e 1168.73 df 1064.71 ef 1025.07 ef 1114.5 167.17 102.93 139.26 n 4 4 4 4 4 20 Totl stndrd devition (SD) of ll 20 observtions; b Averge of the 5 SD s clculted for ech vriety; c SD mong the 5 vrieties. These three vlues provide n estimte of the vrition mong the 20 smples, within ech vriety nd mong the 5 vrieties, respectively. d,e,f Mens within row with different superscripts differ, P < 0.05 42
Tble 2. Digestibility coefficients nd energy vlues of the brley smples. Vriety Item AC-Lcombe B-1602 Bedford Hrrington Mnley Men Totl Avg. SD SD mong SD within vriety vrieties Digestibility coefficient, % Dry mtter 76.48 79.81 75.61 77.95 79.53 77.88 3.39 3.11 1.84 Crude protein 66.39 73.50 66.72 68.01 71.21 69.16 4.29 3.48 3.08 Ether extrct 58.27 68.98 61.20 66.46 65.53 64.09 6.96 5.83 4.30 Acid detergent fibre 13.68 8.31 5.72 10.90 6.29 8.98 9.32 9.40 3.32 Neutrl detergent fibre 55.55 56.80 47.59 56.59 55.45 54.39 6.21 5.34 3.85 Energy 74.57 78.09 73.60 75.87 77.99 76.02 3.45 3.09 2.01 Energy vlues, Mcl/kg Digestible energy 2.872 3.019 2.849 2.931 3.000 2.934 133.10 120.56 75.25 Metbolizble energy 2.798 2.934 2.777 2.853 2.924 2.857 128.78 117.35 71.60 Net energy b 2.092 2.204 2.083 2.156 2.208 2.149 112.25 104.38 59.68 90% DM bsis; bne clculted s NE =.700 x DE + 1.61 x EE +.48 x ST -.91 x CP -.87 x ADF (Noblet et l., 1994) Tble 3. Chemicl components of the brley smples. Brley vriety Item AC-Lcombe B-1602 Bedford Hrrington Mnley Men Totl Avg. SD SD mong SD within vriety vrieties Ash, % 2.59 2.50 2.56 2.54 2.92 2.62 0.39 0.36 0.17 Ether extrct, % 1.58 c 2.06 d 2.13 de 2.36 e 2.09 d 2.05 0.30 0.15 0.28 Crude Protein, % 11.80 13.57 12.86 12.23 12.73 12.64 1.20 1.07 0.67 Strch, % 47.11 48.13 47.97 48.80 49.93 48.38 2.99 2.95 1.05 Gross energy, Mcl/kg 3.852 3.866 3.870 3.863 3.847 3.860 22.64 21.78 9.92 Crude fibre, % 6.24 5.69 6.02 5.63 5.51 5.82 1.02 1.08 0.30 Acid detergent fibre, % 7.24 5.71 6.77 6.46 5.71 6.38 1.32 1.25 0.67 Neutrl detergent fibre, % 25.59 23.87 24.13 24.83 22.34 24.15 2.60 2.56 1.21 Acid detergent lignin, % 1.14 1.07 1.23 1.11 1.15 1.14 0.14 0.13 0.06 Totl NSP b 19.35 c 18.25c 17.56 ce 15.20 d 15.78 de 16.29 2.07 1.35 1.72 Insoluble NSP b 13.89 12.83 12.80 11.42 11.04 12.40 1.65 1.37 1.16 Soluble NSP b 5.46 5.41 4.76 3.78 4.74 4.83 0.94 0.77 0.68 Cellulose, % 4.44 3.60 3.90 3.14 3.12 3.64 0.87 0.74 0.55 Totl rbinoxylns, % 8.94 c 8.50 ce 7.92cd 6.83d 7.29 de 7.89 1.17 0.87 0.86 Insoluble rbinoxylns, % 7.44 7.14 6.84 6.30 6.18 6.78 0.92 0.82 0.54 Soluble rbinoxylns, % 1.50 c 1.35c 1.08 c 0.52 d 1.11c 1.11 0.46 0.33 0.37 Totl ß-glucns, % 3.48 3.71 3.78 3.52 3.29 3.56 0.48 0.48 0.19 Insoluble ß-glucns, % 2.79 2.93 3.01 2.68 2.35 2.75 0.43 0.39 0.26 Clcium, % 0.06 0.07 0.06 0.06 0.06 0.06 0.01 0.01 0.001 Phosphorus, % 0.35 0.36 0.39 0.35 0.39 0.37 0.04 0.04 0.02 n 4 4 4 4 4 20 All chemicl components re reported on 90% DM bsis; b Non-strch polyscchrides; c,d,e Mens in row with different superscript letters differ t P < 0.05 43
Tble 4. Prediction equtions of DE (kcl/kg; 90% DM). No. Eqution Coefficient of Residul stndrd determintion devition 1 DE = 3039-74.4 x ADF + 4.4 x KW + 15.8 x CP.88 50 2 DE = 3357-83.1 x ADF + 2.8 x KW.86 52 3 DE = 3526-92.8 x ADF.85 52 4 DE = 1902-17.3 x NDF + 21.0 x BW + 31.6 x CP.79 67 5 DE = 1489-29.7 x CF + 32.5 x CP + 24.2 x BW.77 70 6 DE = 838 + 32.3 x BW + 38.6 X CP.76 69 7 ME = 3276-81.4 x ADF + 2.6 x KW.88 48 8 ME = 3435-90.4 x ADF.87 49 9 ME = 1976-18.1 x NDF + 19.5 x BW + 27.2 x CP.78 65 10 ME = 862 + 31.3 x BW + 34.5 x CP.75 68 11 ME = 1380-23.7 x CF + 24.9 x BW + 29.7 x CP.75 70 Abbrevitions for the vribles re s follows: BW = bushel weight, CF = crude fibre, CP = crude protein, EE = ether extrct, KW = 1000 kernel weight Tble 5. Vlue of brley smples when vribility in DE ws incorported into typicl grower diet,b. Brley vriety Smple # Brley DE Level Economic vlue (kcl/kg; 90% DM) ($/1000 kg) AC Lcombe 1 2,955 113.10 AC Lcombe 2 2,806 87.47 AC Lcombe 3 2,953 112.80 AC Lcombe 4 2,775 78.08 B 1602 1 3,038 125.35 B 1602 2 3,114 136.58 B 1602 3 3,133 139.39 B 1602 4 2,791 81.08 Bedford 1 2,804 86.78 Bedford 2 2,909 106.30 Bedford 3 2,886 102.91 Bedford 4 2,795 83.14 Hrrington 1 3,114 136.58 Hrrington 2 2,967 114.87 Hrrington 3 2,686 78.12 Hrrington 4 2,957 113.39 Mnley 1 3,035 124.92 Mnley 2 3,121 137.62 Mnley 3 2,846 96.98 Mnley 4 2,998 119.46 Men 2,934 108.75 The price of brley ws $110.00/tonne s of July 25, 1997, Ssktoon, SK.; b The vlue of ech brley smple ws estimted s follows: bsl grower diet ws costed using verge brley energy (2,934 kcl/kg) content nd price ($110/tonne). The diet ws then reformulted to the sme nutrient composition using the ctul DE content of ech brley smple. The vlue of ech brley ws set t the price which resulted in cost of the diet equl to tht of the bsl formultion ($ 214.07). The diet hd to contin minimum of 45% brley. 44