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Use of wild oat groats in starter diets for swine
ANIMAL FEED SCIENCE AND TECHNOLOGY
ELSEVIER
Animal Feed Science and Technology 46 (1994) 229-237
Use of wild oat groats in starter diets for swine P.A. T h a c k e r *'a, F . W . S o s u l s k i b aDepartment of Animal Science, University of Saskatchewan, Saskatoon, Sask. S7N OWO, Canada bDepartment of Crop Science, University of Saskatchewan, Saskatoon, Sask. S7N OWO, Canada (Received 15 April 1993; accepted 28 September 1993)
Abstract Two experiments were conducted to determine the potential of wild oat groats for use in diets fed to starter pigs. In Experiment 1, 180 starter pigs (6 kg) were assigned to either a control diet based on wheat and soya-bean meal or diets containing 250 g kg- 1 domestic oat groats (DOG), domestic oat flakes (DOF), wild oat groats (WOG) or wild oat flakes (WOF) added at the expense of wheat. In Experiment 2, 102 starter pigs (6 kg) were assigned to either a wheat and soya-bean meal based control diet or diets containing WOG as the major energy source supplemented with either 0 or 2.5 g kg- ~fl-glucanase. Chromic oxide (5 g kg- ~) was added to the diet of 36 pigs to determine digestibility coefficients. All pigs were housed in pairs during the 5 week trials and feed consumption was determined on a pen basis at the time of the weekly weighing. In Experiment 1, there were no significant differences (P< 0.05) in pig performance as a result of any treatment or between barrows and gilts. In Experiment 2, pigs fed WOG as the sole source of energy gained weight slower and with a poorer feed/gain ratio than pigs fed the wheat-based diet (P< 0.05). Supplementation with an enzyme preparation with fl-glucanase activity did not improve pig performance. Digestibility coefficients for dry matter, crude protein and energy were higher (P< 0.05) for pigs fed WOG as an energy source in comparison with wheat. However, enzyme supplementation did not improve nutrient digestibility. These results indicate that WOG can substitute for DOG or wheat at levels as high as 25°/0 of the diet without significantly reducing starter pig performance.
1. Introduction Despite intensive efforts at chemical and cultural control, wild oats continue to c o n t a m i n a t e a significant p r o p o r t i o n o f the world's cereal grain production. Owing to their black-colored hull, these wild oat seeds must be r e m o v e d before *Corresponding author. 0377-8401/94/$07.00 © 1994 Elsevier Science B.V. All fights reserved SSD10377-8401 (93) 00561-9
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the grain can be exported or processed for human consumption (Sosulski et al., 1985 ) and every year large quantities of wild oats are separated at commercial seed cleaning plants. In North America, wild oats are usually marketed as mixed feed oats and are fed almost exclusively to ruminants since the presence of a highly fibrous hull limits their usefulness in diets fed to monogastrics (Beames et al., 1986). However, a technique for dehulling wild oat seeds has been developed (Sosulski and Sosulski, 1985 ) resulting in the availability of wild oat groats for use in livestock feeds. While wild oat groats have been fed successfully to both broiler chicks (Bhargava and Sosulski, 1986; Campbell et al., 1987) and rats (Sosulski et al., 1985 ), their nutritional value for swine has not been assessed. The performance of broiler chicks fed wild oat groats has been shown to be significantly enhanced by enzyme supplementation (Campbell et al., 1987). However, it has not been established if the performance of pigs fed wild oat groats can be similarly improved as a result of supplementation with an enzyme preparation with fl-glucanase activity. Therefore, experiments were conducted to determine the potential of wild oat groats for use as an ingredient in swine diets and to determine whether their nutritive value could be increased through enzyme supplementation.
2. Materials and methods
2.1. Preparation of test ingredients Domestic oat groats (DOG) were produced from domestic oats by heat stabilization, kiln drying and mechanical dehulling as described by Kent (1983). Domestic oat flakes (DOF) were produced from DOG by cooking the groats in a steamer, roiling the hot cooked product to produce a flake and then drying (Kent, 1983). Wild oat groats (WOG) and wild oat flakes (WOF) were prepared according to the procedures outlined by Sosulski and Sosulski ( 1985 ). In this process, the hulls of purified mixed feed oats are cracked by impact and separated from the groat by air aspiration. The green groats are then steam-treated and kilned to produce WOG. Further processing with a groat cutter and hot roller mill results in the production of WOF. All oat products were ground immediately before incorporation into mixed diets (Table 1 ).
2.2. Experiment I Three replicates of 60 4-week-old crossbred starter pigs (Yorkshire × Landrace) weighing an average of 6 kg were utilized in this experiment. The animals were assigned to one of five dietary treatments on the basis of sex, weight and litter. The control diet was based on wheat and soya-bean meal while the remaining diets contained 250 g kg-~ DOG (Federated Cooperatives, Saskatoon, Sask. ), DOF (Robin Hood Multifoods, Saskatoon, Sask. ), WOG (Cal-
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Table 1 Chemical composition of test ingredients ($ kg- ~air-dry basis) Domestic oat groat (DOG)
Domestic oat flake (DOF)
Wild oat groat (WOG)
Wild oat flake (WOF)
127.3 145.3 63.3 33.4 19.1 1.4 3.7
107.4 122.2 73.1 14.8 16.9 0.5 4.0
113.5 199.2 77.5 38.0 21.7 0.7 4.9
101.7 190.6 87.4 12.8 20.2 0.6 5.2
9.7 3.1 5.0 11.0 5.6 1.7 7.8 4.6 8.1
8.1 2.9 4.3 9.4 5.0 1.7 7.2 3.2 6.8
11.9 4.2 6.8 14.1 6.6 2.9 10.3 5.2 9.4
12.5 4.3 6.4 14.1 6.8 2.7 10.6 4.9 10.2
Chemical analysis Moisture Crude protein Ether extract Crude fiber Ash Calcium Phosphorus
Essential amino acids Arginine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Valine
mar Grains, Regina, Sask.) or WOF (Calmar Grains) added at the expense of wheat (Table 2). All diets were formulated to contain approximately 200 g kgcrude protein and were supplemented with synthetic lysine so that all diets supplied at least 8.9 g kg-~ lysine (Table 3). All other nutrients were present at a level to meet or exceed National Research Council requirements (NRC, 1988). All diets were fed in pelleted form. The experimental animals were housed in pairs (two barrows or two gilts) in 0.6 m × 1.2 m pens mounted over a totally slatted floor. Feed and water were available ad libitum. The pigs were weighed at weekly intervals during the 5 week trial and feed consumption was determined on a pen basis at the time of the weekly weighing.
2.3. Experiment 2 Three replicates of 34 4-week-old starter pigs (6 kg) were obtained from the same genetic source as those used in Experiment 1 and were assigned to one of three dietary treatments on the basis of sex, weight and litter. The control diet was based on wheat and soya-bean meal while the other two diets contained wild oat groats as the major energy source and contained either 0 or 2.5 g kg -m flglucanase enzyme (Table 2). All diets were formulated to contain approximately 200 g kg- ~ crude protein and 10 g kg-i lysine (Table 3 ). All other nutrients were
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Table 2 Formulation of experimental diets (g k g - ~) Ingredient
Experiment 1
Experiment 2
Wheat Domestic Domestic Wild oat Wild oat Wheat Wild oat Wild oat oat groat oat flake groat flake groat groat + enzyme Wheat 795.9 Oat product Soya-bean meal 139.5 Limestone 12.5 Dicalcium phosphate 15.0 Salt 5.0 Tallow 25.0 Vitamin/mineral 5.0
541.4 250.0 144.4 12.5 15.0 5.0 25.0 5.0
523.6 250.0 162.5 12.5 15.0 5.0 25.0 5.0
583.3 250.0 101.9 12.5 15.0 5.0 25.0 5.0
576.9 250.0 108.4 12.5 15.0 5.0 25.0 5.0
683.0 259.5 12.5 15.0 5.0 20.0 5.0
846.5 96.0 12.5 15.0 5.0 20.0 5.0
-
-
844.0 96.0 12.5 15.0 5.0 20.0 5.0
mix 1
Synthetic lysine C r u d e enzyme
2.1 .
1.7 .
.
1.4 .
2.3 .
.
2.2 .
2.5
1Supplied (kg -1 diet): 8250 I U v i t a m i n A; 550 IU v i t a m i n D3; 27 IU v i t a m i n E; 4 m g v i t a m i n K; 1 nag thiamin; 8 m g riboflavin; 44 m g niacin; 33 nag panthothenic acid; 2 8 / , g v i t a m i n B~2; 500rag choline chloride; 0.25 nag biotin; 6 m g copper; 80 m g iron; 24.7 m g manganese; 153 m g zinc; 0.1 m g selenium; 133 m g ethoxyquin.
present at a level to meet or exceed NRC requirements (NRC, 1988 ). The experimental animals were fed and housed as in Experiment 1. The enzyme supplement used was a commercially available product obtained from an Aspergillus niger fermentation which had been selected for enhanced pglucanase production (GNC Bioferm, Saskatoon, Sask. ). The final product contained dehydrated malt sprouts as a carder and supplied 750 fl-glucanase units per gram (one unit of activity defined as a change of 1 in the inverse specific viscosity coefficient; manufacturer's specifications). Lesser quantities of other enzymes (pentosanase, cellulase, amylase, arabinofuranosidase and pectinase) were also present. Thirty-six of the pigs (18 barrows and 18 gilts) from the growth experiment were used to determine the digestibility of dry matter, crude protein and energy in the experimental diets. The pigs were housed under the same conditions as those used in the growth trial and were fed similar diets modified only by the addition of 5 g kg- 1 chromic oxide as a digestibility indicator. The chromic oxide containing diets were fed for a period of 10 days starting on Day 25 of the experiment. The pens were thoroughly cleaned on Day 33 and a fresh fecal sample was taken twice daily from each pen on Days 34 and 35. The feces were then taken to the laboratory and frozen until needed for subsequent analysis.
2. 4. Analytical methods Samples of feed and feces were analyzed for moisture, crude protein, ash, ether extract and neutral detergent fiber according to the methods of the Association
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Table 3 Chemical analysis of experimental diets (g kg- 1 air-dry basis) Experiment 1
Experiment 2
Wheat Domestic Domestic Wild oat Wild oat Wheat Wild oat Wild oat oat groat oat flake groat flake groat groat+ enzyme Chemical analysis Moisture 103.7 99.2 Crude protein 201.4 193.3 Ether extract 43.7 54.0 Ash 41.6 42.0 Neutraldetergent fiber 97.0 88.4 Calcium 8.6 8.8 Phosphorus 6.8 6.9
Essential amino acids Arginine Histidine Isoleucine Leueine Lysine Methionine Phenylalanine Threonine Valine
10.3 5.3 7.5 13.2 8.9 3.0 9.3 6.1 8.6
11.0 5.3 7.5 13.3 8.9 3.1 9.3 6.3 8.8
91.3 194.0 63.4 36.4 78.8 8.1 7.0
101.3 195.7 56.1 34.7 95.0 7.6 7.1
99.1 198.8 58.7 39.0 83.9 7.8 7.2
11.4 5.5 7.6 13.9 9.1 3.5 9.5 6.5 9.1
10.9 5.2 7.2 13.1 9.1 3.2 9.2 6.0 8.9
10.9 5.2 7.3 13.1 9.1 3.3 9.3 6.1 8.9
107.9 98.7 2 1 1 . 1 207.0 38.3 81.7 60.0 54.1 97.7 71.0 9.7 8.6 7.6 8.4
14.0 6.3 7.6 16.4 11.2 2.4 10.7 7.6 9.4
14.7 5.5 7.4 I5.8 9.9 2.5 11.0 7.1 10.2
99.7 203.0 70.8 54.3 68.2 8.3 8.3
14.6 5.4 7.7 15.0 9.8 2.5 10.9 7.1 10.0
of Official Analytical Chemists (AOAC, 1980). Gross energy was determined with an adiabatic oxygen bomb calorimeter. Amino acid analyses were performed using a Perkin-Elmer Series 4 Liquid Chromatograph following hydrolysis for 22 h with 6 N HC1. Methionine was determined after pefformic acid oxidation by the method of Moore (1963) modified to exclude the use of hydrogen bromide. Chromic oxide was determined by the method of Fenton and Fenton (1979).
2.5. Statistical analysis All data were analyzed using the General Linear Models procedure of the Statistical Analysis System Institute (SAS, 1985). The main effects in the model were treatment, sex and their interaction. Means were compared using StudentNewman-Keuls' multiple range test when preceded by a significant F-test.
3. Results Chemical analysis of the main dietary ingredients tested in Experiment 1 is presented in Table 1. At 199 g kg-1 crude protein, WOG contained almost 40%
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more protein than DOG ( 145 g kg-1 ). WOG appeared to be higher in crude fat, crude fiber and ash than its domestic counterpart. The essential amino acids content was also higher in WOG than DOG. These differences in chemical composition between WOG and DOG are of a similar magnitude to those reported previously (Sosulski and Sosulski, 1985; Sosulski et al., 1985; Bhargava and Sosulski, 1986). The additional processing required for the production of DOF and WOF did not appear to have a major impact on nutrient content, although minor differences were apparent between the chemical composition of groats and flakes. Most evident were differences in crude fiber content. In Experiment 1, there were no significant differences (P<0.05) in pig performance as a result of any treatment or between barrows and gilts (Table 4). Pigs fed diets supplemented with WOG tended to eat less feed than pigs fed DOG. As a consequence, the growth rate of pigs fed the diets based on WOG-was slightly slower than for pigs fed DOG. However, the feed/gain ratio was similar. The additional processing required to produce a flake (toasting and rolling) did not improve the nutritive value of either DOF or WOF but rather appeared to have a detrimental effect. Although not statistically significant (P> 0.05 ), there was a trend for slower growth rates and a poorer feed/gain ratio when pigs were fed DOF or WOF in comparison with their respective groat. In Experiment 2, pigs fed WOG as the main source of energy consumed significantly (P < 0.10) less feed than pigs fed wheat (Table 5 ). As a consequence, the growth rates of pigs fed wild oat based diets was significantly poorer ( P < 0.05 ) than those of pigs fed wheat. In addition, the feed/gain ratio was also poorer ( P < 0.05 ) when WOG were included in the diet. Enzyme supplementation had no effect on pig performance. Growth rates were also not affected by the sex of the pig but the feed/gain ratio was significantly better for males than females (P<0.07). The poorer performance of pigs fed diets containing WOG did not appear to result from impaired digestibility as digestibility coefficients for dry matter, crude protein and energy were significantly ( P < 0.05 ) higher for pigs fed WOG as an energy source in comparison with digestibility coefficients obtained for pigs fed wheat (Table 5 ). Enzyme supplementation had no significant effect on nutrient digestibility. However, digestibility coefficients for dry matter and energy were significantly higher for females than for males (P< 0.05 ). Table 4 Performance of starter pigs fed varous oat products (Experiment 1 ) Wheat Domestic Domestic Wild oat Wild oat SEM Males Females SEM oat groat oat flake groat flake Dailygain (kg) 0.39 Dailyfeed (kg) 0.65 Feed/gainratio 1.67
0.39 0.65 1.67
0.38 0.65 1.71
0.37 0.61 1.65
0.35 0.60 1.71
0.02 0.03 0.07
0.39 0.63 1.78
0.39 0.63 1.67
0.01 0.02 0.04
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Table 5 Performance and digestibility coefficients of pigs fed wild oat groats with or without enzyme treatment (Experiment 2) t Wheat
Wild oat groat
Wild oat groat + enzyme
SEM
Males
Females
SEM
0.29 0.54 1.89 a
0.01 0.02 0.05
Performance Daily gain (kg) Daily feed (kg) Feed/gain ratio
0.34" 0.57 c 1.69"
0.26 b 0.49 a 1.89 b
0.27 b 0.52 ~ 1.95 b
0.02 0.03 0.06
0.30 0.52 1.77 ¢
Digestibility coefficients Dry matter (%) Crude protein (%) Energy (%)
82.2" 79.5" 80.8 a
84.6 b 83.8 b 83.2 b
83.9 b 83.8 I' 83.4 b
0.41 0.91 0.50
82.8 a 81.6 81.6 a
84.4 b 83.1 83.3 b
0.33 0.74 0.41
tWithin main effect, means followed by different superscripts differ: ,bp < 0.05; c,ap< 0.10.
4. Discussion
An examination of the chemical analysis of WOG revealed a feedstuff with considerable potential for use as an ingredient in swine diets. The high content of crude protein is unusual for a cereal grain and nearly approaches the protein level commonly encountered in many of the legumes and oilseeds which are used as protein supplements in swine rations (NRC, 1988 ). As a consequence, diets based on WOG may require less supplemental protein in order to meet the pigs requirements for essential amino acids than diets based on other cereal grains. The protein quality of WOG appears to be high since the results of the amino acid analysis revealed that only lysine and threonine were not present in adequate amounts to meet the amino acid requirements of the 5-20 kg pig (NRC, 1988). The high protein quality of WOG has been documented previously in feeding trials conducted with weanling rats, where the protein efficiency ratio (PER) obtained with wild oat groats as the sole dietary protein source was 1.87, about 85% of the PER value of the casein control (Sosulski et al., 1985). WOG contain a higher level of ether extract than DOG. Chemical analysis has shown that almost 90% of the lipid in WOG is in the form of triglyceride (Sosulski, 1984). These triglycerides are highly unsaturated, with oleic, linoleic and linolenic acid levels being 46%, 35% and 2% respectively of the total fatty acids (Campbell et al., 1987). These polyunsaturated fatty acids are desirable nutritionally, but they are also subject to oxidative instability during storage, especially after seed grinding. DOG are used fairly widely in creep and starter rations for swine because they contain a relatively low crude fiber content and are palatable and highly digestible (Lin et al., 1987 ). The results of the present experiments indicated that WOG can substitute for DOG or wheat at levels as high as 25% of the diet without significantly reducing starter pig performance. Unfortunately, WOG cannot be used as the major energy source in diets fed to
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starter pigs since Experiment 2 indicated that the growth rate of pigs fed WOG was significantly poorer than that of pigs fed wheat. This reduction in growth rate may be partially explained by the slightly lower feed consumption of pigs fed WOG in comparison with wheat. The specific factor responsible for the reduction in intake has not been identified. The poorer performance of pigs fed diets containing WOG did not appear to result from impaired digestibility as digestibility coefficients were significantly higher for pigs fed WOG as an energy source in comparison with wheat. High digestibility coefficients for energy and protein (93.5% and 87.5%, respectively) have been reported previously for rats fed diets based on WOG (Sosulski et al., 1985). The reduction in performance when WOG were used as the main energy source would also not appear to be due to the presence of fl-glucans in the WOG since the addition of fl-glucanase to the diet had no significant effect on pig performance. This finding is in contrast to work with poultry where the nutritional value of WOG for broiler chickens has been shown to be significantly enhanced by supplementation of the diet with enzymes capable of degrading fl-glucans (Campbell et al., 1987). In poultry, fl-glucans are solubilized during digestion, resulting in a viscous intestinal fluid that interferes with digestion (BurneR, 1966). Supplementation with fl-glucanase has been shown to significantly reduce digesta viscosity (White et al., 1983 ) and thereby improve performance. However, in swine fl-glucanase supplementation does not appear to reduce digesta viscosity (Bedford et al., 1992) and therefore, previous attempts to improve pig performance by supplementation of swine diets with fl-glucanase has not produced improvements comparable to those observed with poultry (Thacker et al., 1988, 1989). The additional processing required to produce a flake (toasting and rolling) appeared to have a detrimental effect on starter pig performance since the performance of pigs fed the DOF and WOF was slightly poorer than that obtained when pigs were fed the respective untreated groat. This may be a reflection of heat damage to the oat protein occurring during the flaking process. The flaking process would likely increase the cost of DOF and WOF relative to DOG and WOG, and since these products do not appear to support improved performance over those obtained with the raw ingredient, it is doubtful if this additional processing would be cost effective. In conclusion, the results of the present experiments indicated that WOG can substitute for DOG or wheat at levels as high as 25% of the diet without significantly reducing starter pig performance. However, they cannot be used as the major energy source. Supplementation with p-glucanase enzyme had no effect on pig performance. In addition, further processing to produce a flake appeared to have a detrimental effect on starter pig performance. Further work is necessary in order to determine the cause of the poorer performance when WOG are included at high levels in starter diets.
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5. Acknowledgments This study was funded by the Province of Saskatchewan's Farm Lab Fund. The authors wish to thank B. Schann and R. Herman of the Prairie Swine Centre for care and management of the experimental animals.
6. References Association of Official Analytical Chemists, 1980. Official Methods of Analysis, 13th edn. AOAC, Washington, DC. Beames, R.M., Tait, R.M. and Litsky, J., 1986. Grain screenings as a dietary component for pigs and sheep. 1. Botanical and chemical composition. Can. J. Anita. Sci., 66:473-481. Bedford, M.R., Patience, J.E, Classen, H.L. and Inborr, J., 1992. The effect of dietary enzyme supplementation of rye and barley on digestion and subsequent performance in pigs. Can. J. Anita. Sci., 72: 97-105. Bhargava, K.K. and Sosulski, F.W., 1986. Wild oat groats in broiler diets. Poult. Sci., 65: 330-336. Burnett, G.S., 1966. Studies of viscosity as the probable factor involved in the improvement of certain badeys for chickens by enzyme supplementation. Br. Poult. Sci., 7: 55-75. Campbell, G.L., Sosulski, F.W., Classen, H.L. and Ballance, G.M., 1987. Nutritive value of irradiated and beta-glucanase treated wild oat groats (Arenafatua L.) for broiler chicks. Anita. Feed Sci. Technol., 16: 243-252. Fenton, T.W. and Fenton, M., 1979. An improved method for the determination of chromic oxide in feed and feces. Can. J. Anita. Sci., 59: 631-634. Kent, N.L., 1983. Oats. In: N.L. Kent (Editor), Technology of Cereals, 3rd edn. Pergamon Press, Oxford, pp. 165-174. Lin, F.D., Knabe, D.A. and Tanksley, T.D., 1987. Apparent digestibilityof amino acids, gross energy and starch in corn, sorghum, wheat, barley, oat groats and wheat middlings for growing pigs. J. Anita. Sci., 64: 1655-1663. Moore, S., 1963. On the determination of cystine as cysteic acid. J. Biol. Chem., 238: 235-237. National Research Council, 1988. Nutrient Requirements of Domestic Animals. No. 2. Nutrient Requirements of Swine, 9th edn. NAS-NRC, Washington, DC. Sosulski, F.W., 1984. Wild oats: A new food commodity. Univ. Alta. Agric. For. Bull., 7:60-61. Sosulski, F.W. and Sosulski, K., 1985. Processing and composition of wild oat groats (Arenafatua L.). J. Food Eng., 4: 189-203. Sosulski, F.W., Sosulski, K. and Olson, J.P., 1985. Nutritive value of wild oat groats and flakes. Can. Inst. Food Sci. Technol., 18: 220-225. Statistical Analysis System Institute, 1985. SAS Users Guide, Version 5. SAS Institute, Cary, NC. Thacker, P.A., Campbell, G.L. and GrootWassink, J.W.D., 1988. The effect ofbeta-glucanase supplementation on the performance of pigs fed hulless barley. Nutr. Rep. Int., 38:91-99. Thacker, P.A., Campbell, G.L. and GrootWassink, J.W.D., 1989. The effect of sodium bentonite on the performance of pigs fed barley-based diets supplemented with beta-glucanase. Nutr. Rep. Int., 40:613-620. White, W.B., Bird, H.R., Sunde, M.L. and Marlett, J.A., 1983. Viscosity ofbeta-glucan as a factor in the enzymatic improvement of barley for chicks. Poult. Sci., 62: 853-862.
ELSEVIER
Animal Feed Science and Technology 46 (1994) 229-237
Use of wild oat groats in starter diets for swine P.A. T h a c k e r *'a, F . W . S o s u l s k i b aDepartment of Animal Science, University of Saskatchewan, Saskatoon, Sask. S7N OWO, Canada bDepartment of Crop Science, University of Saskatchewan, Saskatoon, Sask. S7N OWO, Canada (Received 15 April 1993; accepted 28 September 1993)
Abstract Two experiments were conducted to determine the potential of wild oat groats for use in diets fed to starter pigs. In Experiment 1, 180 starter pigs (6 kg) were assigned to either a control diet based on wheat and soya-bean meal or diets containing 250 g kg- 1 domestic oat groats (DOG), domestic oat flakes (DOF), wild oat groats (WOG) or wild oat flakes (WOF) added at the expense of wheat. In Experiment 2, 102 starter pigs (6 kg) were assigned to either a wheat and soya-bean meal based control diet or diets containing WOG as the major energy source supplemented with either 0 or 2.5 g kg- ~fl-glucanase. Chromic oxide (5 g kg- ~) was added to the diet of 36 pigs to determine digestibility coefficients. All pigs were housed in pairs during the 5 week trials and feed consumption was determined on a pen basis at the time of the weekly weighing. In Experiment 1, there were no significant differences (P< 0.05) in pig performance as a result of any treatment or between barrows and gilts. In Experiment 2, pigs fed WOG as the sole source of energy gained weight slower and with a poorer feed/gain ratio than pigs fed the wheat-based diet (P< 0.05). Supplementation with an enzyme preparation with fl-glucanase activity did not improve pig performance. Digestibility coefficients for dry matter, crude protein and energy were higher (P< 0.05) for pigs fed WOG as an energy source in comparison with wheat. However, enzyme supplementation did not improve nutrient digestibility. These results indicate that WOG can substitute for DOG or wheat at levels as high as 25°/0 of the diet without significantly reducing starter pig performance.
1. Introduction Despite intensive efforts at chemical and cultural control, wild oats continue to c o n t a m i n a t e a significant p r o p o r t i o n o f the world's cereal grain production. Owing to their black-colored hull, these wild oat seeds must be r e m o v e d before *Corresponding author. 0377-8401/94/$07.00 © 1994 Elsevier Science B.V. All fights reserved SSD10377-8401 (93) 00561-9
230
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the grain can be exported or processed for human consumption (Sosulski et al., 1985 ) and every year large quantities of wild oats are separated at commercial seed cleaning plants. In North America, wild oats are usually marketed as mixed feed oats and are fed almost exclusively to ruminants since the presence of a highly fibrous hull limits their usefulness in diets fed to monogastrics (Beames et al., 1986). However, a technique for dehulling wild oat seeds has been developed (Sosulski and Sosulski, 1985 ) resulting in the availability of wild oat groats for use in livestock feeds. While wild oat groats have been fed successfully to both broiler chicks (Bhargava and Sosulski, 1986; Campbell et al., 1987) and rats (Sosulski et al., 1985 ), their nutritional value for swine has not been assessed. The performance of broiler chicks fed wild oat groats has been shown to be significantly enhanced by enzyme supplementation (Campbell et al., 1987). However, it has not been established if the performance of pigs fed wild oat groats can be similarly improved as a result of supplementation with an enzyme preparation with fl-glucanase activity. Therefore, experiments were conducted to determine the potential of wild oat groats for use as an ingredient in swine diets and to determine whether their nutritive value could be increased through enzyme supplementation.
2. Materials and methods
2.1. Preparation of test ingredients Domestic oat groats (DOG) were produced from domestic oats by heat stabilization, kiln drying and mechanical dehulling as described by Kent (1983). Domestic oat flakes (DOF) were produced from DOG by cooking the groats in a steamer, roiling the hot cooked product to produce a flake and then drying (Kent, 1983). Wild oat groats (WOG) and wild oat flakes (WOF) were prepared according to the procedures outlined by Sosulski and Sosulski ( 1985 ). In this process, the hulls of purified mixed feed oats are cracked by impact and separated from the groat by air aspiration. The green groats are then steam-treated and kilned to produce WOG. Further processing with a groat cutter and hot roller mill results in the production of WOF. All oat products were ground immediately before incorporation into mixed diets (Table 1 ).
2.2. Experiment I Three replicates of 60 4-week-old crossbred starter pigs (Yorkshire × Landrace) weighing an average of 6 kg were utilized in this experiment. The animals were assigned to one of five dietary treatments on the basis of sex, weight and litter. The control diet was based on wheat and soya-bean meal while the remaining diets contained 250 g kg-~ DOG (Federated Cooperatives, Saskatoon, Sask. ), DOF (Robin Hood Multifoods, Saskatoon, Sask. ), WOG (Cal-
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Table 1 Chemical composition of test ingredients ($ kg- ~air-dry basis) Domestic oat groat (DOG)
Domestic oat flake (DOF)
Wild oat groat (WOG)
Wild oat flake (WOF)
127.3 145.3 63.3 33.4 19.1 1.4 3.7
107.4 122.2 73.1 14.8 16.9 0.5 4.0
113.5 199.2 77.5 38.0 21.7 0.7 4.9
101.7 190.6 87.4 12.8 20.2 0.6 5.2
9.7 3.1 5.0 11.0 5.6 1.7 7.8 4.6 8.1
8.1 2.9 4.3 9.4 5.0 1.7 7.2 3.2 6.8
11.9 4.2 6.8 14.1 6.6 2.9 10.3 5.2 9.4
12.5 4.3 6.4 14.1 6.8 2.7 10.6 4.9 10.2
Chemical analysis Moisture Crude protein Ether extract Crude fiber Ash Calcium Phosphorus
Essential amino acids Arginine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Valine
mar Grains, Regina, Sask.) or WOF (Calmar Grains) added at the expense of wheat (Table 2). All diets were formulated to contain approximately 200 g kgcrude protein and were supplemented with synthetic lysine so that all diets supplied at least 8.9 g kg-~ lysine (Table 3). All other nutrients were present at a level to meet or exceed National Research Council requirements (NRC, 1988). All diets were fed in pelleted form. The experimental animals were housed in pairs (two barrows or two gilts) in 0.6 m × 1.2 m pens mounted over a totally slatted floor. Feed and water were available ad libitum. The pigs were weighed at weekly intervals during the 5 week trial and feed consumption was determined on a pen basis at the time of the weekly weighing.
2.3. Experiment 2 Three replicates of 34 4-week-old starter pigs (6 kg) were obtained from the same genetic source as those used in Experiment 1 and were assigned to one of three dietary treatments on the basis of sex, weight and litter. The control diet was based on wheat and soya-bean meal while the other two diets contained wild oat groats as the major energy source and contained either 0 or 2.5 g kg -m flglucanase enzyme (Table 2). All diets were formulated to contain approximately 200 g kg- ~ crude protein and 10 g kg-i lysine (Table 3 ). All other nutrients were
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Table 2 Formulation of experimental diets (g k g - ~) Ingredient
Experiment 1
Experiment 2
Wheat Domestic Domestic Wild oat Wild oat Wheat Wild oat Wild oat oat groat oat flake groat flake groat groat + enzyme Wheat 795.9 Oat product Soya-bean meal 139.5 Limestone 12.5 Dicalcium phosphate 15.0 Salt 5.0 Tallow 25.0 Vitamin/mineral 5.0
541.4 250.0 144.4 12.5 15.0 5.0 25.0 5.0
523.6 250.0 162.5 12.5 15.0 5.0 25.0 5.0
583.3 250.0 101.9 12.5 15.0 5.0 25.0 5.0
576.9 250.0 108.4 12.5 15.0 5.0 25.0 5.0
683.0 259.5 12.5 15.0 5.0 20.0 5.0
846.5 96.0 12.5 15.0 5.0 20.0 5.0
-
-
844.0 96.0 12.5 15.0 5.0 20.0 5.0
mix 1
Synthetic lysine C r u d e enzyme
2.1 .
1.7 .
.
1.4 .
2.3 .
.
2.2 .
2.5
1Supplied (kg -1 diet): 8250 I U v i t a m i n A; 550 IU v i t a m i n D3; 27 IU v i t a m i n E; 4 m g v i t a m i n K; 1 nag thiamin; 8 m g riboflavin; 44 m g niacin; 33 nag panthothenic acid; 2 8 / , g v i t a m i n B~2; 500rag choline chloride; 0.25 nag biotin; 6 m g copper; 80 m g iron; 24.7 m g manganese; 153 m g zinc; 0.1 m g selenium; 133 m g ethoxyquin.
present at a level to meet or exceed NRC requirements (NRC, 1988 ). The experimental animals were fed and housed as in Experiment 1. The enzyme supplement used was a commercially available product obtained from an Aspergillus niger fermentation which had been selected for enhanced pglucanase production (GNC Bioferm, Saskatoon, Sask. ). The final product contained dehydrated malt sprouts as a carder and supplied 750 fl-glucanase units per gram (one unit of activity defined as a change of 1 in the inverse specific viscosity coefficient; manufacturer's specifications). Lesser quantities of other enzymes (pentosanase, cellulase, amylase, arabinofuranosidase and pectinase) were also present. Thirty-six of the pigs (18 barrows and 18 gilts) from the growth experiment were used to determine the digestibility of dry matter, crude protein and energy in the experimental diets. The pigs were housed under the same conditions as those used in the growth trial and were fed similar diets modified only by the addition of 5 g kg- 1 chromic oxide as a digestibility indicator. The chromic oxide containing diets were fed for a period of 10 days starting on Day 25 of the experiment. The pens were thoroughly cleaned on Day 33 and a fresh fecal sample was taken twice daily from each pen on Days 34 and 35. The feces were then taken to the laboratory and frozen until needed for subsequent analysis.
2. 4. Analytical methods Samples of feed and feces were analyzed for moisture, crude protein, ash, ether extract and neutral detergent fiber according to the methods of the Association
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Table 3 Chemical analysis of experimental diets (g kg- 1 air-dry basis) Experiment 1
Experiment 2
Wheat Domestic Domestic Wild oat Wild oat Wheat Wild oat Wild oat oat groat oat flake groat flake groat groat+ enzyme Chemical analysis Moisture 103.7 99.2 Crude protein 201.4 193.3 Ether extract 43.7 54.0 Ash 41.6 42.0 Neutraldetergent fiber 97.0 88.4 Calcium 8.6 8.8 Phosphorus 6.8 6.9
Essential amino acids Arginine Histidine Isoleucine Leueine Lysine Methionine Phenylalanine Threonine Valine
10.3 5.3 7.5 13.2 8.9 3.0 9.3 6.1 8.6
11.0 5.3 7.5 13.3 8.9 3.1 9.3 6.3 8.8
91.3 194.0 63.4 36.4 78.8 8.1 7.0
101.3 195.7 56.1 34.7 95.0 7.6 7.1
99.1 198.8 58.7 39.0 83.9 7.8 7.2
11.4 5.5 7.6 13.9 9.1 3.5 9.5 6.5 9.1
10.9 5.2 7.2 13.1 9.1 3.2 9.2 6.0 8.9
10.9 5.2 7.3 13.1 9.1 3.3 9.3 6.1 8.9
107.9 98.7 2 1 1 . 1 207.0 38.3 81.7 60.0 54.1 97.7 71.0 9.7 8.6 7.6 8.4
14.0 6.3 7.6 16.4 11.2 2.4 10.7 7.6 9.4
14.7 5.5 7.4 I5.8 9.9 2.5 11.0 7.1 10.2
99.7 203.0 70.8 54.3 68.2 8.3 8.3
14.6 5.4 7.7 15.0 9.8 2.5 10.9 7.1 10.0
of Official Analytical Chemists (AOAC, 1980). Gross energy was determined with an adiabatic oxygen bomb calorimeter. Amino acid analyses were performed using a Perkin-Elmer Series 4 Liquid Chromatograph following hydrolysis for 22 h with 6 N HC1. Methionine was determined after pefformic acid oxidation by the method of Moore (1963) modified to exclude the use of hydrogen bromide. Chromic oxide was determined by the method of Fenton and Fenton (1979).
2.5. Statistical analysis All data were analyzed using the General Linear Models procedure of the Statistical Analysis System Institute (SAS, 1985). The main effects in the model were treatment, sex and their interaction. Means were compared using StudentNewman-Keuls' multiple range test when preceded by a significant F-test.
3. Results Chemical analysis of the main dietary ingredients tested in Experiment 1 is presented in Table 1. At 199 g kg-1 crude protein, WOG contained almost 40%
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more protein than DOG ( 145 g kg-1 ). WOG appeared to be higher in crude fat, crude fiber and ash than its domestic counterpart. The essential amino acids content was also higher in WOG than DOG. These differences in chemical composition between WOG and DOG are of a similar magnitude to those reported previously (Sosulski and Sosulski, 1985; Sosulski et al., 1985; Bhargava and Sosulski, 1986). The additional processing required for the production of DOF and WOF did not appear to have a major impact on nutrient content, although minor differences were apparent between the chemical composition of groats and flakes. Most evident were differences in crude fiber content. In Experiment 1, there were no significant differences (P<0.05) in pig performance as a result of any treatment or between barrows and gilts (Table 4). Pigs fed diets supplemented with WOG tended to eat less feed than pigs fed DOG. As a consequence, the growth rate of pigs fed the diets based on WOG-was slightly slower than for pigs fed DOG. However, the feed/gain ratio was similar. The additional processing required to produce a flake (toasting and rolling) did not improve the nutritive value of either DOF or WOF but rather appeared to have a detrimental effect. Although not statistically significant (P> 0.05 ), there was a trend for slower growth rates and a poorer feed/gain ratio when pigs were fed DOF or WOF in comparison with their respective groat. In Experiment 2, pigs fed WOG as the main source of energy consumed significantly (P < 0.10) less feed than pigs fed wheat (Table 5 ). As a consequence, the growth rates of pigs fed wild oat based diets was significantly poorer ( P < 0.05 ) than those of pigs fed wheat. In addition, the feed/gain ratio was also poorer ( P < 0.05 ) when WOG were included in the diet. Enzyme supplementation had no effect on pig performance. Growth rates were also not affected by the sex of the pig but the feed/gain ratio was significantly better for males than females (P<0.07). The poorer performance of pigs fed diets containing WOG did not appear to result from impaired digestibility as digestibility coefficients for dry matter, crude protein and energy were significantly ( P < 0.05 ) higher for pigs fed WOG as an energy source in comparison with digestibility coefficients obtained for pigs fed wheat (Table 5 ). Enzyme supplementation had no significant effect on nutrient digestibility. However, digestibility coefficients for dry matter and energy were significantly higher for females than for males (P< 0.05 ). Table 4 Performance of starter pigs fed varous oat products (Experiment 1 ) Wheat Domestic Domestic Wild oat Wild oat SEM Males Females SEM oat groat oat flake groat flake Dailygain (kg) 0.39 Dailyfeed (kg) 0.65 Feed/gainratio 1.67
0.39 0.65 1.67
0.38 0.65 1.71
0.37 0.61 1.65
0.35 0.60 1.71
0.02 0.03 0.07
0.39 0.63 1.78
0.39 0.63 1.67
0.01 0.02 0.04
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Table 5 Performance and digestibility coefficients of pigs fed wild oat groats with or without enzyme treatment (Experiment 2) t Wheat
Wild oat groat
Wild oat groat + enzyme
SEM
Males
Females
SEM
0.29 0.54 1.89 a
0.01 0.02 0.05
Performance Daily gain (kg) Daily feed (kg) Feed/gain ratio
0.34" 0.57 c 1.69"
0.26 b 0.49 a 1.89 b
0.27 b 0.52 ~ 1.95 b
0.02 0.03 0.06
0.30 0.52 1.77 ¢
Digestibility coefficients Dry matter (%) Crude protein (%) Energy (%)
82.2" 79.5" 80.8 a
84.6 b 83.8 b 83.2 b
83.9 b 83.8 I' 83.4 b
0.41 0.91 0.50
82.8 a 81.6 81.6 a
84.4 b 83.1 83.3 b
0.33 0.74 0.41
tWithin main effect, means followed by different superscripts differ: ,bp < 0.05; c,ap< 0.10.
4. Discussion
An examination of the chemical analysis of WOG revealed a feedstuff with considerable potential for use as an ingredient in swine diets. The high content of crude protein is unusual for a cereal grain and nearly approaches the protein level commonly encountered in many of the legumes and oilseeds which are used as protein supplements in swine rations (NRC, 1988 ). As a consequence, diets based on WOG may require less supplemental protein in order to meet the pigs requirements for essential amino acids than diets based on other cereal grains. The protein quality of WOG appears to be high since the results of the amino acid analysis revealed that only lysine and threonine were not present in adequate amounts to meet the amino acid requirements of the 5-20 kg pig (NRC, 1988). The high protein quality of WOG has been documented previously in feeding trials conducted with weanling rats, where the protein efficiency ratio (PER) obtained with wild oat groats as the sole dietary protein source was 1.87, about 85% of the PER value of the casein control (Sosulski et al., 1985). WOG contain a higher level of ether extract than DOG. Chemical analysis has shown that almost 90% of the lipid in WOG is in the form of triglyceride (Sosulski, 1984). These triglycerides are highly unsaturated, with oleic, linoleic and linolenic acid levels being 46%, 35% and 2% respectively of the total fatty acids (Campbell et al., 1987). These polyunsaturated fatty acids are desirable nutritionally, but they are also subject to oxidative instability during storage, especially after seed grinding. DOG are used fairly widely in creep and starter rations for swine because they contain a relatively low crude fiber content and are palatable and highly digestible (Lin et al., 1987 ). The results of the present experiments indicated that WOG can substitute for DOG or wheat at levels as high as 25% of the diet without significantly reducing starter pig performance. Unfortunately, WOG cannot be used as the major energy source in diets fed to
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starter pigs since Experiment 2 indicated that the growth rate of pigs fed WOG was significantly poorer than that of pigs fed wheat. This reduction in growth rate may be partially explained by the slightly lower feed consumption of pigs fed WOG in comparison with wheat. The specific factor responsible for the reduction in intake has not been identified. The poorer performance of pigs fed diets containing WOG did not appear to result from impaired digestibility as digestibility coefficients were significantly higher for pigs fed WOG as an energy source in comparison with wheat. High digestibility coefficients for energy and protein (93.5% and 87.5%, respectively) have been reported previously for rats fed diets based on WOG (Sosulski et al., 1985). The reduction in performance when WOG were used as the main energy source would also not appear to be due to the presence of fl-glucans in the WOG since the addition of fl-glucanase to the diet had no significant effect on pig performance. This finding is in contrast to work with poultry where the nutritional value of WOG for broiler chickens has been shown to be significantly enhanced by supplementation of the diet with enzymes capable of degrading fl-glucans (Campbell et al., 1987). In poultry, fl-glucans are solubilized during digestion, resulting in a viscous intestinal fluid that interferes with digestion (BurneR, 1966). Supplementation with fl-glucanase has been shown to significantly reduce digesta viscosity (White et al., 1983 ) and thereby improve performance. However, in swine fl-glucanase supplementation does not appear to reduce digesta viscosity (Bedford et al., 1992) and therefore, previous attempts to improve pig performance by supplementation of swine diets with fl-glucanase has not produced improvements comparable to those observed with poultry (Thacker et al., 1988, 1989). The additional processing required to produce a flake (toasting and rolling) appeared to have a detrimental effect on starter pig performance since the performance of pigs fed the DOF and WOF was slightly poorer than that obtained when pigs were fed the respective untreated groat. This may be a reflection of heat damage to the oat protein occurring during the flaking process. The flaking process would likely increase the cost of DOF and WOF relative to DOG and WOG, and since these products do not appear to support improved performance over those obtained with the raw ingredient, it is doubtful if this additional processing would be cost effective. In conclusion, the results of the present experiments indicated that WOG can substitute for DOG or wheat at levels as high as 25% of the diet without significantly reducing starter pig performance. However, they cannot be used as the major energy source. Supplementation with p-glucanase enzyme had no effect on pig performance. In addition, further processing to produce a flake appeared to have a detrimental effect on starter pig performance. Further work is necessary in order to determine the cause of the poorer performance when WOG are included at high levels in starter diets.
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5. Acknowledgments This study was funded by the Province of Saskatchewan's Farm Lab Fund. The authors wish to thank B. Schann and R. Herman of the Prairie Swine Centre for care and management of the experimental animals.
6. References Association of Official Analytical Chemists, 1980. Official Methods of Analysis, 13th edn. AOAC, Washington, DC. Beames, R.M., Tait, R.M. and Litsky, J., 1986. Grain screenings as a dietary component for pigs and sheep. 1. Botanical and chemical composition. Can. J. Anita. Sci., 66:473-481. Bedford, M.R., Patience, J.E, Classen, H.L. and Inborr, J., 1992. The effect of dietary enzyme supplementation of rye and barley on digestion and subsequent performance in pigs. Can. J. Anita. Sci., 72: 97-105. Bhargava, K.K. and Sosulski, F.W., 1986. Wild oat groats in broiler diets. Poult. Sci., 65: 330-336. Burnett, G.S., 1966. Studies of viscosity as the probable factor involved in the improvement of certain badeys for chickens by enzyme supplementation. Br. Poult. Sci., 7: 55-75. Campbell, G.L., Sosulski, F.W., Classen, H.L. and Ballance, G.M., 1987. Nutritive value of irradiated and beta-glucanase treated wild oat groats (Arenafatua L.) for broiler chicks. Anita. Feed Sci. Technol., 16: 243-252. Fenton, T.W. and Fenton, M., 1979. An improved method for the determination of chromic oxide in feed and feces. Can. J. Anita. Sci., 59: 631-634. Kent, N.L., 1983. Oats. In: N.L. Kent (Editor), Technology of Cereals, 3rd edn. Pergamon Press, Oxford, pp. 165-174. Lin, F.D., Knabe, D.A. and Tanksley, T.D., 1987. Apparent digestibilityof amino acids, gross energy and starch in corn, sorghum, wheat, barley, oat groats and wheat middlings for growing pigs. J. Anita. Sci., 64: 1655-1663. Moore, S., 1963. On the determination of cystine as cysteic acid. J. Biol. Chem., 238: 235-237. National Research Council, 1988. Nutrient Requirements of Domestic Animals. No. 2. Nutrient Requirements of Swine, 9th edn. NAS-NRC, Washington, DC. Sosulski, F.W., 1984. Wild oats: A new food commodity. Univ. Alta. Agric. For. Bull., 7:60-61. Sosulski, F.W. and Sosulski, K., 1985. Processing and composition of wild oat groats (Arenafatua L.). J. Food Eng., 4: 189-203. Sosulski, F.W., Sosulski, K. and Olson, J.P., 1985. Nutritive value of wild oat groats and flakes. Can. Inst. Food Sci. Technol., 18: 220-225. Statistical Analysis System Institute, 1985. SAS Users Guide, Version 5. SAS Institute, Cary, NC. Thacker, P.A., Campbell, G.L. and GrootWassink, J.W.D., 1988. The effect ofbeta-glucanase supplementation on the performance of pigs fed hulless barley. Nutr. Rep. Int., 38:91-99. Thacker, P.A., Campbell, G.L. and GrootWassink, J.W.D., 1989. The effect of sodium bentonite on the performance of pigs fed barley-based diets supplemented with beta-glucanase. Nutr. Rep. Int., 40:613-620. White, W.B., Bird, H.R., Sunde, M.L. and Marlett, J.A., 1983. Viscosity ofbeta-glucan as a factor in the enzymatic improvement of barley for chicks. Poult. Sci., 62: 853-862.