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Effect of β-glucanase supplementation of cereal-based diets for starter pigs on the apparent digestibilities of dry matter, crude protein and energy
ANIMAL FEED SCIENCE AND TECHNOLOGY
ELSEVIER
Animal Feed Science Technology 59 (1996) 223-231
Effect of P-glucanase supplementation of cereal-based diets for starter pigs on the apparent digestibilities of dry matter, crude protein and energy S. Li, W.C. Sauer *, R. Mosenthin, B. Kerr Department
’
of Agricultural, Food and Nutritional Science, Unioersiry of Alberta, Edmonton, Alta. T6G 2P5, Canada
Received 13 April 1995; accepted 28 September 1995
Abstract A total of 48 PIC pigs (Camborough X Canabrid), average body weight 6.2 kg and 24 d of age, were allotted to four experiments (12 pigs each, equal numbers of barrows and gilts) to determine the effect of P-glucanase supplementation on the digestibilities of crude protein and energy in cereal-based soybean meal diets without or with supplementation of P-glucanase at 0.05, 0.1 and 0.2% (wt./wt.>. The experimental diets were formulated to contain 200 g crude protein kg-’ based on soybean meal and barley (B + SBM, experiment l), wheat (W + SBM, experiment 21, corn (C + SBM, experiment 3) or rye (R + SBM, experiment 4), respectively. Chromic oxide was used as digestibility marker. Each experiment was carried out according to a balanced two-period change-over design. The pigs were fed 3 times daily, equal amounts, at 08:00, 16:00 and 2400 h, at a rate of 5% (wt./wt.) of the individual body weight which was determined at the beginning of the first (6.2 kg) and second (8.1 kg) experimental period. Each experimental period lasted 10 days with 7 days of adaptation followed by 3 days of faeces collection. There was a linear increase (P < 0.05) in the digestibilities of dry matter, crude protein and energy when /3-glucanase was supplemented to the B + SBM diets. The digestibility of crude protein increased (P < 0.05) from 81.6 to 88.5% when 0.2% /3-glucanase was supplemented; the digestibility of energy increased
= Corresponding author. Tel.: (403) 492 7659; Fax.: (4031492 9130. ’Nutri-Quest, Chesterfield, MO., USA.
0377.8401/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved XSDl 0377-8401(95)00909-4
224
S. Li et al./Animal Feed Science Technology 59 (1996) 223-231
(P < 0.05) from 85.2 to 89.5%. There was no effect (P > 0.05) of P-glucanase supplementation on the digestibilities of crude protein and energy in the W + SBM, C + SBM and R -t SBM diets. Keywords: Pig - starter; P-Glucanase; Digestibility; Energy; Crude protein
1. Introduction The mixed-linked (1 + 3)(1 + 4)-P-D-glucans which are frequently present in the endosperm cell walls of barley @man and Graham, 1987) may interfere with digestion and absorption of nutrients and energy. Although there are physiological reasons for augmenting the digestive capacity of pigs with supplementation of P-glucanase, the responses to supplementation have been inconsistent. Most studies on /3-glucanase supplementation to barley-based diets have been carried out with growing and finishing pigs (e.g., Graham et al., 1986; Graham et al., 1989; Thacker et al., 1992a). Only two studies have been reported with starter pigs (Bedford et al., 1992; Thacker et al., 1992b). The objectives of the present studies were to determine the effect of P-glucanase supplementation on the crude protein and energy digestibilities in starter pigs fed a barley soybean meal diet, in addition to wheat-, corn- and rye-based soybean meal diets.
2. Materials and methods 2.1. Animals and diets A total of 48 PIC pigs (Camborough X Canabrid), equal numbers of barrows and gilts, weaned at three weeks of age, were obtained from the University of Alberta swine herd. The average weaning weight of the pigs was 5.9 kg. The pigs were housed individually in metabolic crates (height: 85 cm; length: 70 cm; width: 65 cm) in a barn in which the temperature was maintained between 25 and 28°C. The pigs were fed a starter diet containing 180 g crude protein kg -’ (Sauer et al., 1983) ad libitum. Water was freely available from a low-pressure drinking nipple. Following a period of 3 days, 12 pigs each, 6 barrows and 6 gilts, were assigned to one of four experiments. The pigs were fed a cereal-based soybean meal diet without (basal diet) or with supplementation of 0.05, 0.1 and 0.2% enzyme mixture (Kyowa Hakko Co., Ltd, Kogyo, Japan) which consists of enzymes with endo- and exo-pglucanase and P-glucosidase activities up to 1,000 fibrinolytic activity units g-‘. One thousand fibrinolytic activity units are equivalent to the amount of cellulase to decompose completely 2 filter papers of 1 cm* each in 1 min at 37°C. Hereafter this enzyme mixture is referred to as /3-glucanase. Four cereal-based soybean meal diets were formulated to contain 200 g crude protein kg-’ (Table 1). The cereals were ground through a 2-mm mesh screen prior to incorporation into the diets. Solvent-extracted soybean meal (473 g crude protein kg- ’) was used as the protein supplement. Canola oil was included in the diets to meet the National Research Council (1988) standards for digestible energy. Vitamins, minerals
S. Li et ul./Animul Feed Science Technology 59 (1996) 223-231 Table I Formulation
(g kg-
225
’) of the basal diets Diets a B+SBM
Ingredients: Barley
CtSBM
R+SBM
598.3
Wheat Corn Rye Soybean meal Canola oil Dicalcium monophosphate Calcium carbonate Trace-mineralized salt b Vitamin-mineral premix ’ Chromic oxide d L-Lysine HCL Antibiotics e
W+SBM
699.0 656.7 293.0 68.0 14.0 8.3 3.0 10.0 2.5 1.9 1.0
233.8 25.6 13.4 9.2 3.0 10.0 2.5 2.5 1.0
299.4 3.4 13.8 8.7 3.0
592.9 329.2 39.0 14.6 7.8 3.0
IO.0
10.0
2.5 1.5 I.0
2.5 0.0 1.0
a B + SBM: barley soybean meal diet; W + SBM: wheat soybean meal diet; C + SBM: corn soybean meal diet; R+ SBM: rye soybean meal diet. b Provided (percentage): NaCI, 96.5; ZnO, 0.4; FeCO,, 0.16; MnO, 0.12; 010, 0.033; Ca(IO,),, 0.007; CaO, 0.004. Supplied by Windsor Salt, Toronto, Ont. ’ The vitamin premix provided the following (kg- ’ diet): Vitamin A, 10,000 IU; vitamin D,, 1,000 IU; vitamin E, 80 IU; vitamin K,, 2.0 mg; vitamin B,,, 0.03 mg; riboflavin, 12 mg; niacin, 40 mg; pantothenic acid, 25 mg; choline, 1,000 mg; biotin, 0.25 mg; folic acid, 1.6mg; thiamine, 3.0 mg; Ethoxyquin, 5.0 mg; pyridoxine, 2.25 mg; Fe, 150 mg; Zn, 150 mg; Cu. 125 mg; 1, 0.21 mg; Se, 0.3 mg. Supplied by Hoffmann-LaRoche Ltd., 2455 Meadowprine Blvd., Mississauga, Ont. d Fisher Scientific, Fair Lawn, NJ, 07410. e ASP 250, provided (kg- ’ diet): Aureomycin, 100 mg; Sulfamethazine, 100 mg; Penicillin 50 mg. Supplied by The Upjohn Company, Animal Health Division, Orangeville, Ont.
and lysine were also supplemented to meet or exceed the National Research Council (1988) standards. Chromic oxide (2.5 g kg- ’) was used as digestibility marker. The effect of @glucanase supplementation on the digestibilities of dry matter, crude protein and energy to the barley soybean meal (B + SBM), wheat soybean meal (W + SBM), corn soybean meal (C + SBM) and rye soybean meal (R -I-SBM) diets were determined in experiments 1, 2, 3, and 4, respectively. Each experiment was carried out according to a balanced two-period change-over design (Gill and Magee, 1976). The allotment of the pigs to the experimental diets is presented in Table 2. Four dietary treatments were evaluated and thus the basic plan required six Latin squares of size 2. Each Latin square contained 2 randomly selected animals as rows and 2 periods as columns. Therefore, the complete design required 12 animals. The design was balanced because each treatment was compared with any of the other three treatments in two blocks (animals). Experimental periods were orthogonal to dietary treatments. The daily feed allowance was provided at a rate of 5% (wt./wt.) of the body weight of each pig which was determined 8 h prior to the start of each experimental period. The average body weights of the pigs were 6.2 kg and 8.1 kg at the start of period 1 and 2, respectively. The average body weight of the pigs at the conclusion of the experiment
S. Li et al./Animal
226
Feed Science Technology 59 (1996) 223-231
Table 2 Balanced two-period change-over design a Animal (block)
Period 1
Period 2
1 2 3 4 5 6 7 8 9 10 11 12
A B A C A D B C B D C D
B A C A D A C B D B D C
* A, B, C and D represent the four dietary treatments to which P-glucanase was supplemented at levels of 0, 0.05, 0.10 and 0.20%, respectively.
was 11.2 kg. The pigs were fed 3 times daily, equal amounts, at 08:00, 16:00 and 24:00 h. All pigs consumed their meal allowances within 2 h after feeding. Each experimental period lasted 10 days. Following a 7 day adaptation period faeces were collected from 08:OO h on day 8 until 08:OO h on day Il. Faeces were frozen at - 20°C immediately after collection. The animals used in these experiments were cared for in accordance with the guidelines established by Canadian Council of Animal Care (1980). 2.2. Chemical and statistical analyses After the conclusion of the experiment, faeces were pooled within pig and period for the same dietary treatment. Samples were oven-dried at 65°C for 3 days, ground in a Wiley mill through a 0.8-mm mesh screen and stored at 4°C. Analyses for dry matter and nitrogen were carried out according to the procedures of the Association of Official Analytical Chemists (1984). Analysis for energy was carried out with a Parr Adiabatic Bomb Calorimeter. Analyses for neutral-detergent fibre and acid-detergent fibre were carried out according to principles outlined by Goering and van Soest (1970). Chromic oxide was determined according to Fenton and Fenton (1979). The contents of @glucans in the cereal grains, soybean meal and the diets were determined according to Bamforth (1983) and Henry (1984) with modifications described by Li et al. (1995). Analyses were carried out in duplicate. The chemical analysis of the experimental diets is presented in Table 3. Data were subjected to statistical analysis using the General Linear Model of the Statistical Analysis System Institute Inc. @AS, 1988). The following linear model was used for data analysis: Y = /_L+ T + Pj + B, + Eijk (i=
1,2...T;j=
1,2;k=
1,2 ,... T(T-
1)).
S. Li et al./Animal Table 3 Partial chemical
analysis
Feed Science Technology 59 (1996) 223-231
of the basal diets (g kg-
227
’) a
Diets b
Dry matter Crude protein Cross energy (MJ kg Neutral-detergent fibre Acid-detergent fibre Ether extract p-glucans c
’1
B+SBM
W+SBM
C+SBM
R+SBM
898.0 194.9 161.6 84.4 23.3 75.4 32.3
882.0 192.3 151.7 78.5 24.7 34.4 7.9
882.0 186.1 143.8 81.1 19.4 26.5 2.6
884.0 194.5 152.0 74.3 21.2 46.0 7.1
a As-fed basis. b Refer to Table 1. ’ B-@can 10.0, 3.3,lO.l and 2.7 g kg- ‘, respectively.
content of barley, wheat, corn, rye and soybean meal were 50.8,
where
7; ‘j 4 &ijk
= fixed effect of treatment. = fixed effect of experimental period. = random effect of an animal. = systematic error with N(O,l).
Means of treatments and periods were compared using the Student Newman-Keuls’ multiple range test procedure and the statistical significance level was claimed at P < 0.05; the linear, quadratic and cubic effects of the treatments were analyzed according to the orthogonal polynomial regression procedure (Steel and Torrie, 1980).
Table 4 Effect of P-glucanase energy in pigs a
supplementation
Diets b
B+SBM
WiSBM
C+SBM
R+SBM
on the apparent
digestibilities
Level of P-glucanase
Dry matter d Crude protein d Energy d Dry matter Crude protein Energy Dry matter Crude protein Energy Dry matter Crude protein Energy
(o/o) of dry matter, crude protein and
supplementation
(%)
0.00
0.05
0.10
0.20
84.7 f 81.6 f 85.2 f 86.7 85.1 86.8 85.6 84.4 85.8 86.6 87.0 87.2
87.1 e.f 86.0 e,f 87.8 e.f 87.7 87.8 88.1 84.1 82.5 84.4 87.2 88.4 88.0
86.0 e.f 83.4 f 86.4 e.f 87.8 88.2 88.4 83.7 81.3 83.8 87.2 89.3 88.1
88.3 e 88.5 e 89.5 ’ 87.7 89.1 88.4 85.2 82.7 85.7 86.4 87.1 87.1
SE ’ 0.63 1.21 0.87 0.41 0.91 0.37 0.67 0.98 0.70 0.52 I .02 0.6 I
a Initial and final body weights of the pigs were 6.2 and 1I .2 kg, respectively. b Refer to Table I. ’ Standard error of the mean (n = 6). d Linear effect: dry matter (P = 0.014); crude protein (P = 0.022); energy (P = 0.036). e.f Values in the same row with different superscript letters differ (P < 0.05).
228
S. Li et al./Animal Feed Science Technology 59 (1996) 223-231
Since the quadratic and cubic effects were not significant (P > 0.05>, they were excluded from the model and only the linear regression model Y = a + bx was applied.
3. Results and discussion All pigs remained healthy and consumed their meal allowances throughout the experiment. The digestibilities of dry matter, crude protein and energy in the B + SBM diet increased linearly (P < 0.05) with increasing levels of P-glucanase supplementation (Table 4). The digestibility of energy increased (P < 0.05) from 85.2 to 89.5% and the digestibility of crude protein (P < 0.05) from 81.6 to 88.5% when 0.2% P-glucanase was supplemented. There was no effect (P > 0.05) of P-glucanase supplementation on the digestibilities of dry matter, crude protein and energy in the W + SBM, C + SBM and R + SBM diets. The aforementioned results were not unexpected. As shown in Table 3, among the diets the content of @glucans was highest in B + SBM (32.3 g kg-’ 1. The barley used in this study (c.v. CDC Buck, a variety of hulless barley) contained a relatively high level of /3-glucans (50.8 g kg-’ ). p-glucans, which are frequently present in the endospeim cell walls of barley, may interfere with digestion (Anderson et al., 1978). With supplementation of P-glucanase, there is an increase in the breakdown of endosperm cell wall components, resulting inOmore complete digestion of starch and protein in the small intestine (Hesselman and Aman, 1986). The mechanisms by which p-glucans interfere with digestion and absorption are closely related to their physicochemical properties. p-glucans differ from cellulose in that approximately 30% of the linkages between glucose units are in the form of p(l * 3) and 70% in the form of p(1 + 4) (Fleming and Kawakami, 1977). This branched structure prevents compact folding of the molecules and increases the water-holding capacity which results in its characteristic viscosity and gelling properties. The viscosity and gelling properties tend to hinder intestinal motility (Holt et al., 1979) thereby decreasing the mixing of digesta, digestive enzymes and other necessary components required for digestion and absorption (Vahouny and Cassidy, 1985). These properties may also delay or decrease the digestion and absorption of nutrients by increasing the unstirred fluid layer, creating a physical barrier at the absorption surface on the microvilli (Johnson and Gee, 198 1). With the exception of studies by Thacker et al. (1992b), in which no improvements (P > 0.05) were obtained in the digestibilities of energy and crude protein, no other total tract digestibility studies with p-glucanase supplementation to barley-based diets in young pigs have been reported in the literature. Bedford et al. (1992), using the slaughter method in studies with young pigs (12.1 kg), reported an improvement in nitrogen digestibility in digesta collected from the last three quarters of the small intestine, however, not significant (P > 0.051, and in digesta collected from the colon (P < 0.05). Total tract digestibilities were not determined in aforementioned studies. In studies with older pigs fed barley-based diets (30-50 kg), Graham et al. (1986) observed no effect (P > 0.05) of /?-glucanase supplementation on crude protein and energy digestibilities. Similarly, Graham et al. (1989) found no effect (P > 0.05) of P-glucanase supplementa-
S. Li et al./Animal
Feed Science Technology 59 (1996) 223-231
229
tion on ileal as well as faecal digestibilities of crude protein and energy in studies with 80 kg pigs. Furthermore, Thacker et al. (1992a), in studies with pigs of 41-43 kg, found no effect (P > 0.05) on crude protein and energy digestibilities. On the other hand, in one study with growing pigs (40 kg), improvements (P < 0.05) were reported in energy and crude protein digestibilities (Thacker et al., 1988) upon P-glucanase supplementation. It is rather difficult to consolidate the digestibility results from the different studies. However, in all but one study with older pigs, there was no effect of P-glucanase supplementation on crude protein and energy digestibilities which may explain the lack of response in performance in most of the studies with older pigs (Thacker et al., 1992a, Thacker et al., 1992b; Thacker et al., 1988). In this context Graham et al. (1986), in studies with pigs weighing 30-50 kg, observed more than lo7 lactobacilli g- ’ fresh digesta, including approximately lo6 with /3-glucan degrading ability, in digesta collected from the duodenum and ileum. The ileal p-glucan digestibilities in this study ranged from 95.7 to 97.1%, similar to that observed by Graham et al. (1989) in studies with 80 kg pigs. In addition, Weltzien and Aheme (19871, in studies with pigs of 57.6 kg, reported an ileal p-glucan digestibility of 80%. Furthermore, studies by Graham et al. (1986) and Graham et al. (1989) also showed that p-glucans were completely degraded by the microflora in the large intestine. Based on the previous discussion, it is unlikely that P-glucanase supplementation to barley-based diets for older pigs will improve nutrient and energy digestibilities and performance. At present, there is a scarcity of information on the effect of P-glucanase supplementation on nutrient and energy digestibilities to barley-based diets for young pigs. The results from this study and to a lesser extent from Bedford et al. (1992) showed a positive effect while Thacker et al. (1992b) showed no effect. With respect to performance, Bedford et al. (1992) also showed an improvement (P < 0.051 in average daily gain upon P-glucanase supplementation. Some caution should be exercised in the interpretation of the results obtained in the different studies. Other factors should also be taken into account. These include the activity of the P-glucanase preparation that is supplemented and the /3-glucan content of the barley that is used in the studies. As was shown by Campbell et al. (19891, the P-glucan content in barley is influenced by genotype and environment in which it was grown. The digestibilities of dry matter, crude protein and energy were higher in period 2 than period 1 (Table 5). The differences, although of a small magnitude, were significant (P < 0.05) for the B + SBM, W + SBM and C + SBM diets. These results are in agreement with studies in young pigs reported by Lloyd et al. (1957) and Li and Sauer (1994). The increase in digestibility with age may result from further development of the digestive tract and increased microbial activity in the digestive tract. Kidder and Manners (1978) reported an increase in digestive enzymes secretion, with the exception of lactase, up to 7-8 weeks of age. In conclusion, /3-glucanase supplementation to the B + SBM diet improved (P < 0.05) the digestibilities of dry matter, energy and crude protein in young pigs. There was no effect (P > 0.05) of P-glucanase supplementation to the W + SBM, C + SBM or R + SBM diets. Further studies on /3-glucanase supplementation to barley-based diets
230 Table 5 Effect of experimental pigs a
S. Li et al./Animal Feed Science Technology 59 (1996) 223-231
period on the apparent
Diets b B+SBM
W+ SBM
C+SBM
R+SBM
Dry matter Crude protein Energy Dry matter Crude protein Energy Dry matter Crude protein Energy Dry matter Crude protein Energy
digestibilities
(%) of dry matter, crude protein and energy in
Period 1
Period 2
SE ’
85.4 83.2 86.0 86.6 86.2 87.2 82.2
87.6 86.6 88.4 88.4 88.9 88.6 87.2 85.1 87.5 87.3 88.7 87.9
0.37 0.78 0.56 0.29 0.64 0.26
e e e e e e e
80.3 e 82.4 f 86.4 87.2 87.2
d d d d d d d d e
0.47 0.69 0.49 0.37 0.72 0.43
a Initial and fmal body weights of the pigs were 6.2 and 11.2 kg, respectively. b Refer to Table 1. ’Standard error of the mean (n = 12). d.e’f Values in the same row with different superscript letters differ (P < 0.05).
for young pigs are warranted. These include the determination of ileal amino acid digestibilities and p-glucan degrading activity of the microflora in the digestive tract of young pigs (6-l 1 kg SW>.
Acknowledgements
Financial support provided by the Alberta Agricultural Research Institute and NutriQuest, Chesterfield, MO, USA is gratefully acknowledged. The authors are also indebted to Mr. J. Hopp, Mr. R. Allan and Mrs. A. Cheng for their assistance with animal care, sample collection and chemical analysis.
References Aman, P. and Graham, H., 1987. Analysis of total and insoluble mixed-linked (1 + 3). (1 + 4)-/3-D-glucans in barley and oats. J. Agric. Food Chem., 35: 704-709. Anderson, M.A., Cook, J.A. and Stone, B.A., 1978. Enzymatic determination of 1,3: 1.4p-glucans in barley grain and other cereals. J. Inst. Brew., 84: 233-239. Association of Official Analytical Chemists, 1984. Official Methods of Analyses. 14th edn. AOAC, Washington, DC. Bamforth, C.W. 1983. Penicillium Funiculosum as a source of /3-glucanase for the estimation of barley p-glucans. J. Inst. Brew., 89: 391-392. Bedford, M.R., Patience, J.F., Classen, H.L. and Inborr, J., 1992. The effect of dietary enzyme supplementation of rye- and barley-based diets on digestion and subsequent performance in weanling pigs. Can. J. Anim. Sci., 72: 97-105. 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. Anim. Feed. Sci. Technol., 26: 221-230.
S. Li et ul./Animal Feed Science Technology 59 (1996) 223-231 Canadian Council of Animal Care, 1980. Guide to the Care and Use of Experimental addendum). Ottawa, Ont. Fenton, T.W. and Fenton, M., 1979. An improved
procedure
for the determination
231 Animals.
Vol. 1. (with
of chromic
oxide in feed
and faeces. Can. J. Anim. Sci., 59: 631-634. Fleming, M. and Kawakami, K., 1977. Studies of the tine structure of p-glucans of barley extracted at different temperatures. Carbohyd. Res., 57: 15-23. Gill, J.L. and Magee, W.T., 1976. Balanced two-period changeover design for several treatments. J. Anim. Sci., 42: 775-777. Goering, H.K. and van Soest, P.J., 1970. Forage tibre analysis. USDA Agric. Handbook, 379. Washington, DC. Graham, H., Fadel, J.G., Newman, C.W. and Newman, P.K., 1989. Effect of pelleting and P-glucanase supplementation on the ileal and faecal digestibilities of a barley-based diet in the pig. J. Anim. Sci., 67: 1293-1298. Graham, H., Hesselman, K., Jonsson, E. and Aman, P., 1986. Influence of P-glucanase supplementation on digestion of a barley-based diet in the pig gastrointestinal tract. Nutr. Rep. Int., 34: 1089- 1096. Henry, R.J. 1984. A simplified enzymatic method for the determination of l-3, 1-4 p-glucans in barley. J. Inst. Brew., 90: 178-180. Hesselman, K. and Aman, P., 1986. The effect of P-glucanase on the utilization of starch and nitrogen by broiler chickens fed on barley of low- or high-viscosity. Anim. Feed Sci. Technol., 15: 83-93. Holt, S., Heading, R.C., Carter, D.C., Prescott, L.F. and Tothill, P., 1979. Effect of gel-fibre on gastric emptying and absorption of glucose and paracetamol. The Lancet, 1: 636-639. Kidder, D.E. and Manners, M.J., 1978. Digestion in the Pig. Kingston Press, Bristol. Johnson, I.T. and Gee, J.M., 1981. Effect of gel-forming gums on the intestinal unstirred layer and sugar transport in vitro. Gut, 22: 3988403. Li, S. and Sauer, W.C., 1994. The effect of fat content on amino acid digestibility in young pigs. J. Anim. Sci., 72: 1737- 1743. Li, S., Sauer, WC., Huang, S.X. and Gabert, V.M., 1995. Effect of P-glucanase supplementation on ileal and faecal digestibility of /!I-glucans, crude protein and amino acids in young pigs. J. Anim. Sci., (Accepted). Lloyd, L.E., Crampton, E.W. and Mackay, V.G., 1957. The digestibility of ration nutrients by three vs seven-week old pigs. J. Anim. Sci., 16: 383-388. National Research Council, 1988. Nutrient Requirements of Swine. 9th edn. National Academy of Science, Washington, DC. Sauer, W.C., J4rgensen, H. and Berzins, R., 1983. A modified nylon bag technique for determining apparent digestibilities of protein in feedstuffs for pigs. Can. J. Anim. Sci., 63: 233-237. Statistical Analysis System Institute Inc., 1988. SAS/STAT User’s Guide (Release 6.03). SAS Gary, NC. Steel, R.G.D. and Torrie, J.H., 1980. Principles and Procedures of Statistics. 2nd edn. McGraw-Hill, New York. Thacker, P.A., Campbell, G.L. and Groat-Wassink, J.W.D., 1988. The effect of beta-glucanase supplementation on the performance of pigs fed hulless barley. Nutr. Rep. Int., 38: 91-99. Thacker, P.A., Campbell, G.L. and Groot-Wassink, J.W.D., 1992a. The effect of salinomycin and enzyme supplementation on nutrient digestibility and the performance of pigs fed barley- or rye-based diets. Can. J. Anim. Sci., 72: 117-125. Thacker, P.A., Campbell, G.L. and Groot-Wassink, J.W.D., 1992b. The effect of organic acids and enzyme supplementation on the performance of pigs fed barley-based diets. Can. J. Anim. Sci., 72: 395-402. Vahouny, G.V. and Cassidy, M.M., 1985. Dietary fibre and absorption of nutrients. Proc. Sot. Exp. Biol. Med., 180: 432-446. Weltzien, E.M. and Aheme, F.X., 1987. The effects of anaerobic storage and processing of high-moisture barley on its ileal digestibility by, and performance of, growing swine. Can. J. Anim. Sci., 67: 829-840.
ELSEVIER
Animal Feed Science Technology 59 (1996) 223-231
Effect of P-glucanase supplementation of cereal-based diets for starter pigs on the apparent digestibilities of dry matter, crude protein and energy S. Li, W.C. Sauer *, R. Mosenthin, B. Kerr Department
’
of Agricultural, Food and Nutritional Science, Unioersiry of Alberta, Edmonton, Alta. T6G 2P5, Canada
Received 13 April 1995; accepted 28 September 1995
Abstract A total of 48 PIC pigs (Camborough X Canabrid), average body weight 6.2 kg and 24 d of age, were allotted to four experiments (12 pigs each, equal numbers of barrows and gilts) to determine the effect of P-glucanase supplementation on the digestibilities of crude protein and energy in cereal-based soybean meal diets without or with supplementation of P-glucanase at 0.05, 0.1 and 0.2% (wt./wt.>. The experimental diets were formulated to contain 200 g crude protein kg-’ based on soybean meal and barley (B + SBM, experiment l), wheat (W + SBM, experiment 21, corn (C + SBM, experiment 3) or rye (R + SBM, experiment 4), respectively. Chromic oxide was used as digestibility marker. Each experiment was carried out according to a balanced two-period change-over design. The pigs were fed 3 times daily, equal amounts, at 08:00, 16:00 and 2400 h, at a rate of 5% (wt./wt.) of the individual body weight which was determined at the beginning of the first (6.2 kg) and second (8.1 kg) experimental period. Each experimental period lasted 10 days with 7 days of adaptation followed by 3 days of faeces collection. There was a linear increase (P < 0.05) in the digestibilities of dry matter, crude protein and energy when /3-glucanase was supplemented to the B + SBM diets. The digestibility of crude protein increased (P < 0.05) from 81.6 to 88.5% when 0.2% /3-glucanase was supplemented; the digestibility of energy increased
= Corresponding author. Tel.: (403) 492 7659; Fax.: (4031492 9130. ’Nutri-Quest, Chesterfield, MO., USA.
0377.8401/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved XSDl 0377-8401(95)00909-4
224
S. Li et al./Animal Feed Science Technology 59 (1996) 223-231
(P < 0.05) from 85.2 to 89.5%. There was no effect (P > 0.05) of P-glucanase supplementation on the digestibilities of crude protein and energy in the W + SBM, C + SBM and R -t SBM diets. Keywords: Pig - starter; P-Glucanase; Digestibility; Energy; Crude protein
1. Introduction The mixed-linked (1 + 3)(1 + 4)-P-D-glucans which are frequently present in the endosperm cell walls of barley @man and Graham, 1987) may interfere with digestion and absorption of nutrients and energy. Although there are physiological reasons for augmenting the digestive capacity of pigs with supplementation of P-glucanase, the responses to supplementation have been inconsistent. Most studies on /3-glucanase supplementation to barley-based diets have been carried out with growing and finishing pigs (e.g., Graham et al., 1986; Graham et al., 1989; Thacker et al., 1992a). Only two studies have been reported with starter pigs (Bedford et al., 1992; Thacker et al., 1992b). The objectives of the present studies were to determine the effect of P-glucanase supplementation on the crude protein and energy digestibilities in starter pigs fed a barley soybean meal diet, in addition to wheat-, corn- and rye-based soybean meal diets.
2. Materials and methods 2.1. Animals and diets A total of 48 PIC pigs (Camborough X Canabrid), equal numbers of barrows and gilts, weaned at three weeks of age, were obtained from the University of Alberta swine herd. The average weaning weight of the pigs was 5.9 kg. The pigs were housed individually in metabolic crates (height: 85 cm; length: 70 cm; width: 65 cm) in a barn in which the temperature was maintained between 25 and 28°C. The pigs were fed a starter diet containing 180 g crude protein kg -’ (Sauer et al., 1983) ad libitum. Water was freely available from a low-pressure drinking nipple. Following a period of 3 days, 12 pigs each, 6 barrows and 6 gilts, were assigned to one of four experiments. The pigs were fed a cereal-based soybean meal diet without (basal diet) or with supplementation of 0.05, 0.1 and 0.2% enzyme mixture (Kyowa Hakko Co., Ltd, Kogyo, Japan) which consists of enzymes with endo- and exo-pglucanase and P-glucosidase activities up to 1,000 fibrinolytic activity units g-‘. One thousand fibrinolytic activity units are equivalent to the amount of cellulase to decompose completely 2 filter papers of 1 cm* each in 1 min at 37°C. Hereafter this enzyme mixture is referred to as /3-glucanase. Four cereal-based soybean meal diets were formulated to contain 200 g crude protein kg-’ (Table 1). The cereals were ground through a 2-mm mesh screen prior to incorporation into the diets. Solvent-extracted soybean meal (473 g crude protein kg- ’) was used as the protein supplement. Canola oil was included in the diets to meet the National Research Council (1988) standards for digestible energy. Vitamins, minerals
S. Li et ul./Animul Feed Science Technology 59 (1996) 223-231 Table I Formulation
(g kg-
225
’) of the basal diets Diets a B+SBM
Ingredients: Barley
CtSBM
R+SBM
598.3
Wheat Corn Rye Soybean meal Canola oil Dicalcium monophosphate Calcium carbonate Trace-mineralized salt b Vitamin-mineral premix ’ Chromic oxide d L-Lysine HCL Antibiotics e
W+SBM
699.0 656.7 293.0 68.0 14.0 8.3 3.0 10.0 2.5 1.9 1.0
233.8 25.6 13.4 9.2 3.0 10.0 2.5 2.5 1.0
299.4 3.4 13.8 8.7 3.0
592.9 329.2 39.0 14.6 7.8 3.0
IO.0
10.0
2.5 1.5 I.0
2.5 0.0 1.0
a B + SBM: barley soybean meal diet; W + SBM: wheat soybean meal diet; C + SBM: corn soybean meal diet; R+ SBM: rye soybean meal diet. b Provided (percentage): NaCI, 96.5; ZnO, 0.4; FeCO,, 0.16; MnO, 0.12; 010, 0.033; Ca(IO,),, 0.007; CaO, 0.004. Supplied by Windsor Salt, Toronto, Ont. ’ The vitamin premix provided the following (kg- ’ diet): Vitamin A, 10,000 IU; vitamin D,, 1,000 IU; vitamin E, 80 IU; vitamin K,, 2.0 mg; vitamin B,,, 0.03 mg; riboflavin, 12 mg; niacin, 40 mg; pantothenic acid, 25 mg; choline, 1,000 mg; biotin, 0.25 mg; folic acid, 1.6mg; thiamine, 3.0 mg; Ethoxyquin, 5.0 mg; pyridoxine, 2.25 mg; Fe, 150 mg; Zn, 150 mg; Cu. 125 mg; 1, 0.21 mg; Se, 0.3 mg. Supplied by Hoffmann-LaRoche Ltd., 2455 Meadowprine Blvd., Mississauga, Ont. d Fisher Scientific, Fair Lawn, NJ, 07410. e ASP 250, provided (kg- ’ diet): Aureomycin, 100 mg; Sulfamethazine, 100 mg; Penicillin 50 mg. Supplied by The Upjohn Company, Animal Health Division, Orangeville, Ont.
and lysine were also supplemented to meet or exceed the National Research Council (1988) standards. Chromic oxide (2.5 g kg- ’) was used as digestibility marker. The effect of @glucanase supplementation on the digestibilities of dry matter, crude protein and energy to the barley soybean meal (B + SBM), wheat soybean meal (W + SBM), corn soybean meal (C + SBM) and rye soybean meal (R -I-SBM) diets were determined in experiments 1, 2, 3, and 4, respectively. Each experiment was carried out according to a balanced two-period change-over design (Gill and Magee, 1976). The allotment of the pigs to the experimental diets is presented in Table 2. Four dietary treatments were evaluated and thus the basic plan required six Latin squares of size 2. Each Latin square contained 2 randomly selected animals as rows and 2 periods as columns. Therefore, the complete design required 12 animals. The design was balanced because each treatment was compared with any of the other three treatments in two blocks (animals). Experimental periods were orthogonal to dietary treatments. The daily feed allowance was provided at a rate of 5% (wt./wt.) of the body weight of each pig which was determined 8 h prior to the start of each experimental period. The average body weights of the pigs were 6.2 kg and 8.1 kg at the start of period 1 and 2, respectively. The average body weight of the pigs at the conclusion of the experiment
S. Li et al./Animal
226
Feed Science Technology 59 (1996) 223-231
Table 2 Balanced two-period change-over design a Animal (block)
Period 1
Period 2
1 2 3 4 5 6 7 8 9 10 11 12
A B A C A D B C B D C D
B A C A D A C B D B D C
* A, B, C and D represent the four dietary treatments to which P-glucanase was supplemented at levels of 0, 0.05, 0.10 and 0.20%, respectively.
was 11.2 kg. The pigs were fed 3 times daily, equal amounts, at 08:00, 16:00 and 24:00 h. All pigs consumed their meal allowances within 2 h after feeding. Each experimental period lasted 10 days. Following a 7 day adaptation period faeces were collected from 08:OO h on day 8 until 08:OO h on day Il. Faeces were frozen at - 20°C immediately after collection. The animals used in these experiments were cared for in accordance with the guidelines established by Canadian Council of Animal Care (1980). 2.2. Chemical and statistical analyses After the conclusion of the experiment, faeces were pooled within pig and period for the same dietary treatment. Samples were oven-dried at 65°C for 3 days, ground in a Wiley mill through a 0.8-mm mesh screen and stored at 4°C. Analyses for dry matter and nitrogen were carried out according to the procedures of the Association of Official Analytical Chemists (1984). Analysis for energy was carried out with a Parr Adiabatic Bomb Calorimeter. Analyses for neutral-detergent fibre and acid-detergent fibre were carried out according to principles outlined by Goering and van Soest (1970). Chromic oxide was determined according to Fenton and Fenton (1979). The contents of @glucans in the cereal grains, soybean meal and the diets were determined according to Bamforth (1983) and Henry (1984) with modifications described by Li et al. (1995). Analyses were carried out in duplicate. The chemical analysis of the experimental diets is presented in Table 3. Data were subjected to statistical analysis using the General Linear Model of the Statistical Analysis System Institute Inc. @AS, 1988). The following linear model was used for data analysis: Y = /_L+ T + Pj + B, + Eijk (i=
1,2...T;j=
1,2;k=
1,2 ,... T(T-
1)).
S. Li et al./Animal Table 3 Partial chemical
analysis
Feed Science Technology 59 (1996) 223-231
of the basal diets (g kg-
227
’) a
Diets b
Dry matter Crude protein Cross energy (MJ kg Neutral-detergent fibre Acid-detergent fibre Ether extract p-glucans c
’1
B+SBM
W+SBM
C+SBM
R+SBM
898.0 194.9 161.6 84.4 23.3 75.4 32.3
882.0 192.3 151.7 78.5 24.7 34.4 7.9
882.0 186.1 143.8 81.1 19.4 26.5 2.6
884.0 194.5 152.0 74.3 21.2 46.0 7.1
a As-fed basis. b Refer to Table 1. ’ B-@can 10.0, 3.3,lO.l and 2.7 g kg- ‘, respectively.
content of barley, wheat, corn, rye and soybean meal were 50.8,
where
7; ‘j 4 &ijk
= fixed effect of treatment. = fixed effect of experimental period. = random effect of an animal. = systematic error with N(O,l).
Means of treatments and periods were compared using the Student Newman-Keuls’ multiple range test procedure and the statistical significance level was claimed at P < 0.05; the linear, quadratic and cubic effects of the treatments were analyzed according to the orthogonal polynomial regression procedure (Steel and Torrie, 1980).
Table 4 Effect of P-glucanase energy in pigs a
supplementation
Diets b
B+SBM
WiSBM
C+SBM
R+SBM
on the apparent
digestibilities
Level of P-glucanase
Dry matter d Crude protein d Energy d Dry matter Crude protein Energy Dry matter Crude protein Energy Dry matter Crude protein Energy
(o/o) of dry matter, crude protein and
supplementation
(%)
0.00
0.05
0.10
0.20
84.7 f 81.6 f 85.2 f 86.7 85.1 86.8 85.6 84.4 85.8 86.6 87.0 87.2
87.1 e.f 86.0 e,f 87.8 e.f 87.7 87.8 88.1 84.1 82.5 84.4 87.2 88.4 88.0
86.0 e.f 83.4 f 86.4 e.f 87.8 88.2 88.4 83.7 81.3 83.8 87.2 89.3 88.1
88.3 e 88.5 e 89.5 ’ 87.7 89.1 88.4 85.2 82.7 85.7 86.4 87.1 87.1
SE ’ 0.63 1.21 0.87 0.41 0.91 0.37 0.67 0.98 0.70 0.52 I .02 0.6 I
a Initial and final body weights of the pigs were 6.2 and 1I .2 kg, respectively. b Refer to Table I. ’ Standard error of the mean (n = 6). d Linear effect: dry matter (P = 0.014); crude protein (P = 0.022); energy (P = 0.036). e.f Values in the same row with different superscript letters differ (P < 0.05).
228
S. Li et al./Animal Feed Science Technology 59 (1996) 223-231
Since the quadratic and cubic effects were not significant (P > 0.05>, they were excluded from the model and only the linear regression model Y = a + bx was applied.
3. Results and discussion All pigs remained healthy and consumed their meal allowances throughout the experiment. The digestibilities of dry matter, crude protein and energy in the B + SBM diet increased linearly (P < 0.05) with increasing levels of P-glucanase supplementation (Table 4). The digestibility of energy increased (P < 0.05) from 85.2 to 89.5% and the digestibility of crude protein (P < 0.05) from 81.6 to 88.5% when 0.2% P-glucanase was supplemented. There was no effect (P > 0.05) of P-glucanase supplementation on the digestibilities of dry matter, crude protein and energy in the W + SBM, C + SBM and R + SBM diets. The aforementioned results were not unexpected. As shown in Table 3, among the diets the content of @glucans was highest in B + SBM (32.3 g kg-’ 1. The barley used in this study (c.v. CDC Buck, a variety of hulless barley) contained a relatively high level of /3-glucans (50.8 g kg-’ ). p-glucans, which are frequently present in the endospeim cell walls of barley, may interfere with digestion (Anderson et al., 1978). With supplementation of P-glucanase, there is an increase in the breakdown of endosperm cell wall components, resulting inOmore complete digestion of starch and protein in the small intestine (Hesselman and Aman, 1986). The mechanisms by which p-glucans interfere with digestion and absorption are closely related to their physicochemical properties. p-glucans differ from cellulose in that approximately 30% of the linkages between glucose units are in the form of p(l * 3) and 70% in the form of p(1 + 4) (Fleming and Kawakami, 1977). This branched structure prevents compact folding of the molecules and increases the water-holding capacity which results in its characteristic viscosity and gelling properties. The viscosity and gelling properties tend to hinder intestinal motility (Holt et al., 1979) thereby decreasing the mixing of digesta, digestive enzymes and other necessary components required for digestion and absorption (Vahouny and Cassidy, 1985). These properties may also delay or decrease the digestion and absorption of nutrients by increasing the unstirred fluid layer, creating a physical barrier at the absorption surface on the microvilli (Johnson and Gee, 198 1). With the exception of studies by Thacker et al. (1992b), in which no improvements (P > 0.05) were obtained in the digestibilities of energy and crude protein, no other total tract digestibility studies with p-glucanase supplementation to barley-based diets in young pigs have been reported in the literature. Bedford et al. (1992), using the slaughter method in studies with young pigs (12.1 kg), reported an improvement in nitrogen digestibility in digesta collected from the last three quarters of the small intestine, however, not significant (P > 0.051, and in digesta collected from the colon (P < 0.05). Total tract digestibilities were not determined in aforementioned studies. In studies with older pigs fed barley-based diets (30-50 kg), Graham et al. (1986) observed no effect (P > 0.05) of /?-glucanase supplementation on crude protein and energy digestibilities. Similarly, Graham et al. (1989) found no effect (P > 0.05) of P-glucanase supplementa-
S. Li et al./Animal
Feed Science Technology 59 (1996) 223-231
229
tion on ileal as well as faecal digestibilities of crude protein and energy in studies with 80 kg pigs. Furthermore, Thacker et al. (1992a), in studies with pigs of 41-43 kg, found no effect (P > 0.05) on crude protein and energy digestibilities. On the other hand, in one study with growing pigs (40 kg), improvements (P < 0.05) were reported in energy and crude protein digestibilities (Thacker et al., 1988) upon P-glucanase supplementation. It is rather difficult to consolidate the digestibility results from the different studies. However, in all but one study with older pigs, there was no effect of P-glucanase supplementation on crude protein and energy digestibilities which may explain the lack of response in performance in most of the studies with older pigs (Thacker et al., 1992a, Thacker et al., 1992b; Thacker et al., 1988). In this context Graham et al. (1986), in studies with pigs weighing 30-50 kg, observed more than lo7 lactobacilli g- ’ fresh digesta, including approximately lo6 with /3-glucan degrading ability, in digesta collected from the duodenum and ileum. The ileal p-glucan digestibilities in this study ranged from 95.7 to 97.1%, similar to that observed by Graham et al. (1989) in studies with 80 kg pigs. In addition, Weltzien and Aheme (19871, in studies with pigs of 57.6 kg, reported an ileal p-glucan digestibility of 80%. Furthermore, studies by Graham et al. (1986) and Graham et al. (1989) also showed that p-glucans were completely degraded by the microflora in the large intestine. Based on the previous discussion, it is unlikely that P-glucanase supplementation to barley-based diets for older pigs will improve nutrient and energy digestibilities and performance. At present, there is a scarcity of information on the effect of P-glucanase supplementation on nutrient and energy digestibilities to barley-based diets for young pigs. The results from this study and to a lesser extent from Bedford et al. (1992) showed a positive effect while Thacker et al. (1992b) showed no effect. With respect to performance, Bedford et al. (1992) also showed an improvement (P < 0.051 in average daily gain upon P-glucanase supplementation. Some caution should be exercised in the interpretation of the results obtained in the different studies. Other factors should also be taken into account. These include the activity of the P-glucanase preparation that is supplemented and the /3-glucan content of the barley that is used in the studies. As was shown by Campbell et al. (19891, the P-glucan content in barley is influenced by genotype and environment in which it was grown. The digestibilities of dry matter, crude protein and energy were higher in period 2 than period 1 (Table 5). The differences, although of a small magnitude, were significant (P < 0.05) for the B + SBM, W + SBM and C + SBM diets. These results are in agreement with studies in young pigs reported by Lloyd et al. (1957) and Li and Sauer (1994). The increase in digestibility with age may result from further development of the digestive tract and increased microbial activity in the digestive tract. Kidder and Manners (1978) reported an increase in digestive enzymes secretion, with the exception of lactase, up to 7-8 weeks of age. In conclusion, /3-glucanase supplementation to the B + SBM diet improved (P < 0.05) the digestibilities of dry matter, energy and crude protein in young pigs. There was no effect (P > 0.05) of P-glucanase supplementation to the W + SBM, C + SBM or R + SBM diets. Further studies on /3-glucanase supplementation to barley-based diets
230 Table 5 Effect of experimental pigs a
S. Li et al./Animal Feed Science Technology 59 (1996) 223-231
period on the apparent
Diets b B+SBM
W+ SBM
C+SBM
R+SBM
Dry matter Crude protein Energy Dry matter Crude protein Energy Dry matter Crude protein Energy Dry matter Crude protein Energy
digestibilities
(%) of dry matter, crude protein and energy in
Period 1
Period 2
SE ’
85.4 83.2 86.0 86.6 86.2 87.2 82.2
87.6 86.6 88.4 88.4 88.9 88.6 87.2 85.1 87.5 87.3 88.7 87.9
0.37 0.78 0.56 0.29 0.64 0.26
e e e e e e e
80.3 e 82.4 f 86.4 87.2 87.2
d d d d d d d d e
0.47 0.69 0.49 0.37 0.72 0.43
a Initial and fmal body weights of the pigs were 6.2 and 11.2 kg, respectively. b Refer to Table 1. ’Standard error of the mean (n = 12). d.e’f Values in the same row with different superscript letters differ (P < 0.05).
for young pigs are warranted. These include the determination of ileal amino acid digestibilities and p-glucan degrading activity of the microflora in the digestive tract of young pigs (6-l 1 kg SW>.
Acknowledgements
Financial support provided by the Alberta Agricultural Research Institute and NutriQuest, Chesterfield, MO, USA is gratefully acknowledged. The authors are also indebted to Mr. J. Hopp, Mr. R. Allan and Mrs. A. Cheng for their assistance with animal care, sample collection and chemical analysis.
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S. Li et ul./Animal Feed Science Technology 59 (1996) 223-231 Canadian Council of Animal Care, 1980. Guide to the Care and Use of Experimental addendum). Ottawa, Ont. Fenton, T.W. and Fenton, M., 1979. An improved
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and faeces. Can. J. Anim. Sci., 59: 631-634. Fleming, M. and Kawakami, K., 1977. Studies of the tine structure of p-glucans of barley extracted at different temperatures. Carbohyd. Res., 57: 15-23. Gill, J.L. and Magee, W.T., 1976. Balanced two-period changeover design for several treatments. J. Anim. Sci., 42: 775-777. Goering, H.K. and van Soest, P.J., 1970. Forage tibre analysis. USDA Agric. Handbook, 379. Washington, DC. Graham, H., Fadel, J.G., Newman, C.W. and Newman, P.K., 1989. Effect of pelleting and P-glucanase supplementation on the ileal and faecal digestibilities of a barley-based diet in the pig. J. Anim. Sci., 67: 1293-1298. Graham, H., Hesselman, K., Jonsson, E. and Aman, P., 1986. Influence of P-glucanase supplementation on digestion of a barley-based diet in the pig gastrointestinal tract. Nutr. Rep. Int., 34: 1089- 1096. Henry, R.J. 1984. A simplified enzymatic method for the determination of l-3, 1-4 p-glucans in barley. J. Inst. Brew., 90: 178-180. Hesselman, K. and Aman, P., 1986. The effect of P-glucanase on the utilization of starch and nitrogen by broiler chickens fed on barley of low- or high-viscosity. Anim. Feed Sci. Technol., 15: 83-93. Holt, S., Heading, R.C., Carter, D.C., Prescott, L.F. and Tothill, P., 1979. Effect of gel-fibre on gastric emptying and absorption of glucose and paracetamol. The Lancet, 1: 636-639. Kidder, D.E. and Manners, M.J., 1978. Digestion in the Pig. Kingston Press, Bristol. Johnson, I.T. and Gee, J.M., 1981. Effect of gel-forming gums on the intestinal unstirred layer and sugar transport in vitro. Gut, 22: 3988403. Li, S. and Sauer, W.C., 1994. The effect of fat content on amino acid digestibility in young pigs. J. Anim. Sci., 72: 1737- 1743. Li, S., Sauer, WC., Huang, S.X. and Gabert, V.M., 1995. Effect of P-glucanase supplementation on ileal and faecal digestibility of /!I-glucans, crude protein and amino acids in young pigs. J. Anim. Sci., (Accepted). Lloyd, L.E., Crampton, E.W. and Mackay, V.G., 1957. The digestibility of ration nutrients by three vs seven-week old pigs. J. Anim. Sci., 16: 383-388. National Research Council, 1988. Nutrient Requirements of Swine. 9th edn. National Academy of Science, Washington, DC. Sauer, W.C., J4rgensen, H. and Berzins, R., 1983. A modified nylon bag technique for determining apparent digestibilities of protein in feedstuffs for pigs. Can. J. Anim. Sci., 63: 233-237. Statistical Analysis System Institute Inc., 1988. SAS/STAT User’s Guide (Release 6.03). SAS Gary, NC. Steel, R.G.D. and Torrie, J.H., 1980. Principles and Procedures of Statistics. 2nd edn. McGraw-Hill, New York. Thacker, P.A., Campbell, G.L. and Groat-Wassink, J.W.D., 1988. The effect of beta-glucanase supplementation on the performance of pigs fed hulless barley. Nutr. Rep. Int., 38: 91-99. Thacker, P.A., Campbell, G.L. and Groot-Wassink, J.W.D., 1992a. The effect of salinomycin and enzyme supplementation on nutrient digestibility and the performance of pigs fed barley- or rye-based diets. Can. J. Anim. Sci., 72: 117-125. Thacker, P.A., Campbell, G.L. and Groot-Wassink, J.W.D., 1992b. The effect of organic acids and enzyme supplementation on the performance of pigs fed barley-based diets. Can. J. Anim. Sci., 72: 395-402. Vahouny, G.V. and Cassidy, M.M., 1985. Dietary fibre and absorption of nutrients. Proc. Sot. Exp. Biol. Med., 180: 432-446. Weltzien, E.M. and Aheme, F.X., 1987. The effects of anaerobic storage and processing of high-moisture barley on its ileal digestibility by, and performance of, growing swine. Can. J. Anim. Sci., 67: 829-840.