The Utilization of Rye by Growing Chicks as Influenced by Autoclave Treatment, Water Extraction, and Water Soaking

The Utilization of Rye by Growing Chicks as Influenced by Autoclave Treatment, Water Extraction, and Water Soaking TAKIS C. ANTONIOU1 and RONALD R. MARQUARDT 2 Department of Animal Science, University of Manitoba, Winnipeg, Canada R3T 2N2 (Received for publication, March 30, 1982)

1982 Poultry Science 6 2 : 9 1 - 1 0 2 INTRODUCTION S u b s t i t u t i o n of high levels of rye for w h e a t or corn in the diets of growing chicks has always resulted in p o o r e r g r o w t h and feed utilization as well as in beak i m p a c t i o n and excretion of w e t and sticky feces (Smith and M a c l n t y r e , I 9 6 0 ; Moran et al, 1 9 6 9 ; Fernadez et al, 1 9 7 3 ) . T h e p e r f o r m a n c e of rye-fed chicks has been a t t r i b u t e d t o t h e presence of u n k n o w n antinutritional factors depressing t h e palatability of feed (Misir and M a r q u a r d t , 1978a) and t h e digestibility of all n u t r i e n t s ( M a r q u a r d t et al, 1979). As rye has a n u t r i e n t c o n t e n t similar t o t h a t of w h e a t (Miller, 1 9 5 8 ) , att e m p t s have been m a d e in t h e past t o improve its nutritional value for chicks. Smith and

1 2

Department of Agriculture, Nicosia, Cyprus. Reprint requests.

M a c l n t y r e ( 1 9 6 0 ) s h o w e d t h a t a pelleted diet containing 30% rye s u p p o r t e d chick g r o w t h and efficiency of feed utilization equivalent t o t h a t o b t a i n e d o n an all-mash w h e a t diet. Moran et al. ( 1 9 6 9 ) r e p o r t e d t h a t t h e beneficial effect of pelleting rye diets was a t t r i b u t e d t o an imp r o v e m e n t of feed c o n s u m p t i o n as a result of r e d u c e d b e a k i m p a c t i o n . These same a u t h o r s showed t h a t autoclave t r e a t m e n t of rye prior t o diet formulation depressed its nutritive value. However, MacAuliffe et al. ( 1 9 7 6 ) r e p o r t e d t h a t soaking g r o u n d rye in .2N HC1 solution in a 2 : 1 weight t o volume p r o p o r t i o n prior t o autoclave t r e a t m e n t improved considerably t h e efficiency of feed conversion a n d t h e g r o w t h of chicks. Also, Fry et al. ( 1 9 5 8 ) showed t h a t soaking r y e with an equal v o l u m e of w a t e r overnight followed by drying in an oven a t 70 C resulted in similar i m p r o v e m e n t s in t h e g r o w t h of p o u l t r y . Water e x t r a c t i o n of rye improved

91

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ABSTRACT Three experiments were conducted with growing chicks to study the effect of autoclave treatment, water extraction, water soaking, and antibiotic supplementation on the nutritional value of rye grain. Experiment 1 showed that the antinutritional factor(s) in rye grain was not destroyed by autoclaving. This treatment for 10 or 30 min, respectively, depressed feed utilization by 9 and 14% in the rye fed chicks and by only 2 and 4% in the wheat fed birds because of reduced digestibility of all nutrients. The detrimental effect of rye grain was partly overcome by increased feed intake. Experiment 2 demonstrated that rye grain contains a water-soluble, sticky, and hydroscopic factor forming highly viscous aqueous solutions. The addition of this factor to a wheat-based diet depressed chick performance to that obtained from feeding extracted rye because of the factor's interference with palatability of the feed and the digestion and absorption of all nutrients including fat and most of the individual amino acids. Extraction of rye twice improved chick performance and the digestibility of all nutrients, but all of these criteria were still inferior compared to those of wheat-fed chicks. The residual antinutritional activity of extracted rye was attributed to the partially insoluble nature of this factor. Chick performance was also improved by penicillin supplementation of diets containing rye, extracted rye, or water extract. In Experiment 3, chick growth and feed utilization were markedly improved with increasing soaking time (in the presence of an antimicrobial agent) or nonautoclaved rye, but soaking of autoclaved rye had no effect. The improvement of chick performance was attributed to a sharp depression with time of the viscosity of a water extract from nonautoclaved rye. This suggested the degradation of the antinutritional factor(s) by endogenous enzymes in the nonautoclaved water-soaked rye. It may be concluded that autoclave treatment protects the antinutritional factor against the inactivation that occurs when rye is soaked in water. Inactivation of the soluble factor is also associated with a decrease in the viscosity of an extract of rye. The factor also appears to be located in both the soluble and insoluble portion of the grain and depresses the retention of all nutrients. (Key words: chicks, rye grain utilization, autoclave, extraction, antibiotic treatment)

92

ANTONIOU AND MARQUARDT

MATERIALS AND METHODS

Puma rye and Glenlea wheat used in this study were ground to pass through a 2 mm screen. Rye contained less than .05% ergot bodies; this level had no influence on chick performance (Misir and Marquardt, 1978a). The diets, except for amino acid levels in Experiment 1 and 2, were formulated to meet the minimum requirements for all nutrients according to the National Research Council (NRC, 1971) (Experiment 1 and 2) or NRC (1977) (Experiment 3) for replacement pullets (0 to 6 weeks). In Experiments 1 and 2, dietary amino acid levels were slightly below NRC recommendations with methionine calculated to be the most limiting amino acid, being 20% below recommended levels. The diets in each experiment were made isonitrogenous either by varying the amount of protein supplement or by adding pure synthetic amino acids and were made isocaloric by varying the level of corn starch, fat, or nonnutritive bulk (cellulose). Chicks, Management, and Experiment Design. Day-old White Leghorn cockerels purchased from a commercial hatchery were housed in thermostatically controlled (Petersime) battery brooders with raised wire screen floors equipped with continuous lighting. From the time of arrival to the start of the experiments when the chicks were 7 days old, the birds were fed a commercial chick starter crumbled diet containing a minimum of 21% protein. Prior to the start of the experiment the chicks were fasted for 4 hr. Thereafter they

were placed in weight groups from which they were randomly assigned to die experimental groups (replicates) that had the same mean weight. Feed and water were supplied ad libitum. The birds were also starved 4 hr prior to weighing at the end of each experiment. Experiment 1. The effect of autoclave treatment of grain and penicillin supplementation on the performance of chicks fed rye or wheat diets was studied in this experiment. Autoclaving of ground grains was performed prior to their incorporation in the diets; the grains were placed in trays to a depth of 2 cm and autoclaved by steam at 121 C for 10 or 30 min. A 2(rye vs. wheat) X 2(0 vs. 200 mg penicillin/kg diet) X 3(0, 10, or 30 min autoclaving) factorial arrangement of the dietary treatments was used with six replicates of 8 birds each. The average initial chick weight ± standard error (SE) was 58 ± .5 g. The experimental period was 7 days. Formulas and analyses of diets are given in Table 1. Experiment 2. The effect of water extraction of rye and penicillin supplementation on the nutritional value of rye diets was examined in a 2(0 vs. 200 mg penicillin/kg diet) X 6(rye, extracted rye, extracted rye plus freezedried extract, wheat, wheat plus freeze-dried, or wheat plus heat-dried extract) factorial arrangement of dietary treatment with four replicates of 4 birds each. The average initial chick weight ± SE in this 9-day experiment was 69.0 ± .5 g. Two different procedures were used for the extraction of rye. In the first procedure, most of the operations were carried out near 0 C in order to minimize inactivation of the antinutritional factor(s). Ground rye (600 g) was mixed with 6 liters of distilled water, pulverized for 5 min by means of a SD45N Tekmar homogenizer (Cincinnati, OH), and subsequently agitated for 40 min at room temperature by using a kitchen type mixer. The mixture was allowed to stand for 1 hr in an ice bath and thereafter it was centrifuged at 1000 X g for 5 min at 0 C in a Sorvall Superspeed RC2-B centrifuge. The precipitate was resuspended in 10 volumes of distilled water, agitated for 40 min, and centrifuged as previously described. The pooled supernatants were freeze-dried, yielding a brown hydroscopic, porous, and sticky solid representing 16% of the original dry matter of the extracted rye. This product was designated as the "freezedried extract". The water extracted rye was also freeze-dried. In the second extraction

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significantly the growth and feed utilization of chicks compared to unextracted rye whereas addition of the freeze-dried extract to corn or wheat-based diets retarded chick performance (Fernadez et al., 1973). Supplementation of rye diets with 50 mg penicillin per kilogram diet supported growth comparable to similarly formulated wheat-based diets (MacAuliffe and McGinnis, 1971) whereas enzyme supplementation had no effect (Moran et al., 1969). The objectives of this study were to establish if the nutritional value of rye for chicks could be improved by inactivation or removal of the antinutritional factor(s) in rye alone or in combination with penicillin supplementation of rye diets and to establish if additional information could be obtained regarding the nature and the stability of the factor following soaking and autoclaving of rye grain.

TREATMENTS AND NUTRITIONAL VALUE OF RYE

Experiment 3. T h e objective of this exp e r i m e n t was t o s t u d y t h e effect of w a t e r soaking for various periods (0, 12, and 22 hr) on t h e stability of t h e antinutritional factor(s) of r a w o r autoclaved ( 1 0 m i n at 121 C) rye grain. O n e kilogram quantities of g r o u n d rye were m i x e d with 2 liters of distilled w a t e r for 10 min in t h e presence of 3 ml t o l u e n e t o inhibit microbial g r o w t h . T h e samples were freeze-dried after they had been allowed t o

stand in tightly covered trays at r o o m temperature for t h e prescribed periods. Seven dietary t r e a t m e n t s (six based o n rye and one o n wheat) were used in this 7-day test with four replicates of 5 birds each. T h e initial average chick weight ± SE was 65.5 ± .4 g. F o r m u l a s and analyses of t h e diets are s h o w n in Table 3. T o test t h e effect of autoclave t r e a t m e n t on t h e viscosity of rye extracts, duplicate 2 0 g samples of finely g r o u n d , nonautoclaved rye and w h e a t and autoclaved rye ( 1 0 , 20, and 4 0 m i n ) were mixed with 10 volumes (w/v) of .2 M phosphate buffer (pH 5.3) for 2 0 min in t h e presence of . 0 2 % sodium azide t o inhibit microbial g r o w t h . Drews ( 1 9 7 1 ) d e m o n s t r a t e d t h a t this was t h e o p t i m u m p H for the activity of enz y m e s responsible for t h e degradation of t h e high viscosity factor (pentosans) in rye doughs. T h e samples were centrifuged at 9,000 X g for 10 min, and t h e viscosities of s u p e r n a t a n t s were d e t e r m i n e d after 0 and 14 h r by measuring t h e time required for a certain volume of e x t r a c t t o pass through t h e capillary t u b e of a viscometer in a water b a t h ( 3 0 C). Analyses. Samples of rye, wheat, e x t r a c t e d rye, extracts, diets, and feces were analyzed by m e t h o d s of Association of Official Analytical Chemists, (AOAC, 1970) for o n e or m o r e of

TABLE 1. Formulas and analyses of the diets (Experiment 1) Ingredients

Rye (11.9% protein) Wheat (11.6% protein) Soybean oil Basal mixture 0 Penicillin0 Chemical analyses" Protein (N X 6.25) Fat Dry matter ME (kcal/kg) e

Rye diets a

Wheat diets a

^At)

63.2

65.2 4.0 30.8

6.0 30.8 +

19.9 ± .4 10.4 ± .4 91.9 ± .7 2,940

+

19.9 ± .4 8.6 ± .1 92.3 ± .2 2,940

Rye or wheat diets contained either raw or autoclaved cereal each with or without added penicillin. See Materials and Methods for further detail. The basal mixture consisted of (% of diet): meat meal (48.8% protein), 28.4; vitamin mix, 1.0; mineral mix, .5; corn starch, .5; and chromic oxide, .4. The composition of vitamin and mineral mixes have been described (Marquardt et al, 1979). Supplied as penicillin G Procaine salt by Sigma Chem. Co., St. Louis, MO, and contained 1000 units/mg. A mixture of corn starch or corn starch and penicillin was added to the diets to provide 0 or 250 mg penicillin/kg diet. d

Mean + SE. Values for ME were calculated.

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p r o c e d u r e , 3 kg quantities of g r o u n d rye were m i x e d with 15 liters of distilled water a n d were allowed t o stand for 6 h r at r o o m t e m p e r a t u r e with occasional stirring. After t h e m i x t u r e had remained overnight at 5 C, t h e t o p liquid was removed by siphon and evaporated at 80 C u n d e r reduced pressure. This p r o d u c t was freeze-dried for further elimination of water and was designated as t h e "heat-dried e x t r a c t " . T h e e x t r a c t e d rye obtained by this m e t h o d was discarded. Both water e x t r a c t s and t h e freezedried water e x t r a c t e d rye were analysed for p r o t e i n and a m i n o acid c o n t e n t prior t o form u l a t i o n of the diet. T h e water extracts were a d d e d at 12.5% of t h e diet, which was equivalent t o a p p r o x i m a t e l y 22% of t h e grain. F o r m u l a s and analyses of t h e diets are given in Table 2.

93

19.2 ± .2 8.6 ± .3 91.0 + .1 2,910

+

32.40 .76 .84

66.00

Rye (A)

19.2 + .1 8.8 ± .3 89.5 ± 0 2,910

32.40 .50 1.05 3.05 ±

63.00

Wheat (B)

18.7 ± .2 8.7 + 0I 92.7 + .1 2,910

+

32.40 .50 3.35 3.74

60.00

19.9 8.6 92.3 2,910

32.4 7.4 1.3

12.5

46.3

C + free dried extract (D)

The same as in Experiment 1. A mixture of corn starch and penicillin was added to the diets to supply 200 mg

Supplied by ICN, Cleveland, OH.

Mean ± SE. f ME values were calculated.

e

c

The composition of the amino acid mixtures (% of diet) for diets A, B, C, and F respectively, was: L-arginin .82; L-histidine HCl, .02, .03, .04, .04; L-isoleucine, .03, .04, .08, .06; L-leucine, .08, .07, .14, .10; L-lysine HCl, phenylalanine, .06, .09, .20, .16; L-threonine, .03, .05, .07, .05; L-valine, .04, .07, .10, .09; for diet D, L-glutamic nine, .08; and DL-phenylalanine, .06: and for diet E, L-arginine HCl, .07; L-lysine HCl, .08; and DL-methionine,.03.

a The basal mixture was composed of (% of diet): meat meal (46.8% protein), 26; soybean oil, 4.5; vitamin m and mineral mixes were the same as in Experiment 1.

Rye (12.0% protein) Wheat (12.1% protein) Extracted rye (9% protein) Rye extract (freeze-dried, 26% protein) Rye extract (heat-dried, 12% protein) Basal mixture a Corn starch Amino acid mixture'' Cellulose (cellufil) c Penicillin^ Chemical analyses e Protein (N X 6.25) Fat Dry matter ME (kcal/kg) f

Ingredients

Extracted rye (C)

Dietary designations

TABLE 2. Formulas and analyses of the diets (Experiment 2

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TREATMENTS AND NUTRITIONAL VALUE OF RYE

Statistical analysis was performed as described by Snedecor and Cochran ( 1 9 6 7 ) . T r e a t m e n t m e a n s were subjected to t h e Student-Newman-Keul's multiple range test.

RESULTS Experiment 1. T r e a t m e n t m e a n s and summary of analysis of variance are shown in Table 4. All main effects for grain, autoclaving time, and penicillin level were significant ( P < . 0 1 ) e x c e p t for effect of autoclaving time o n weight

gain and retention of dry m a t t e r . T h e performance of birds fed t h e rye diets in all cases was inferior t o t h a t for birds fed t h e w h e a t diets. O t h e r main effects are discussed subsequently relative t o their interactions. T h e grain X penicillin interaction except for fat digestibility d e m o n s t r a t e d t h a t penicillin supplem e n t a t i o n was m o r e beneficial w h e n added t o rye as c o m p a r e d t o w h e a t diets. Autoclaving for 10 or 30 min improved ( P < . 0 1 ) feed intake by 5 and 6%, b u t it reduced ( P < . 0 1 ) the efficiency of feed conversion by 7 and 10%, t h e r e t e n t i o n of p r o t e i n (N X 6.25) by 0 and 8%, and t h e digestibility of fat by 12 and 1 1 % , respectively, c o m p a r e d t o 0 min autoclaving time. T h e grain X autoclaving time interaction for t h e efficiency of feed conversion ( P < . 0 1 ) and r e t e n t i o n of dry m a t t e r ( P < . 0 5 ) indicated t h a t an increase of t h e autoclaving time from 0 to 10 or 30 min depressed t h e feed utilization of rye-fed birds by 9 and 14%, respectively, whereas t h e corresponding reduction in t h e wheat-fed birds were only 2 and 4%. T h e corresponding changes for t h e r e t e n t i o n of dry m a t t e r were 1 and — 5 % for the rye and 0 and 1% for t h e wheat-fed birds. T h e autoclaving time X penicillin interaction ( P < . 0 5 ) indicated t h a t p r o t e i n retention was improved when penicillin was added t o t h e diet t h a t contained n o n a u t o c l a v e d grain (23%) c o m p a r e d t o grain autoclaved for either 10 (8%) or 30 m i n (12%). T h e three-way

TABLE 3. Formulas and analyses of the diets (Experiment 3) Ingredients

Rye (9.9% protein) Wheat (12.1% protein) Meat meal (43.5% protein) Corn starch Amino acid mixture 0 Basal mixture 0 Cellulose (celufil) d Calculated analyses Protein (N X 6.25) ME (kcal/kg)

Rye diets a

Wheat diet

*.'«)-

-'-

58.00 29.00 4.45 .65 7.90

19.00 2,910

58.00 27.50 3.00 7.90 3.60 19.00 2,910

A total of six rye diets were prepared. See Materials and Methods for details on treatment procedures. The amino aicd mixture contained (% of diet): L-glutamic acid, .35; L-isoleucine, .06; L-leucine, .10; DL-phenylalanine, .06; L-threonine, .03; and L-valine, .05. The basal mixture contained the following (% of diet): syoybean oil, 6.0; vitamin mix, 1.0; mineral mix, .5; and chromic oxide, .4. Vitamin and mineral mixes were the same as in Experiment 1. See Table 1 for source.

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t h e following constituents: dry m a t t e r , nitrogen, and crude fat. Chromic oxide was determined b y t h e m e t h o d of Williams et al. ( 1 9 6 3 ) . A m i n o acid analyses in E x p e r i m e n t 2 were c o n d u c t e d by t h e m e t h o d of Moore and Stein ( 1 9 6 3 ) with a Beckman A u t o m a t i c A m i n o Acid Analyzer. Duplicate samples of each diet and single samples of the excreta were h y d r o l y z e d in vacuo with 6N HC1 at 121 C for 16 hr. Analyses of t r y p t o p h a n and sulfurcontaining a m i n o acids were o m i t t e d because of t h e e x t r a steps requried in their d e t e r m i n a t i o n s . Also, glycine d e t e r m i n a t i o n was o m i t t e d because this amino acid can be derived in varying quantities from uric acid in t h e excreta during acid hydrolysis. T h e percentage dietary n u t r i e n t retained equaled (g n u t r i e n t / g r a m of diet — g n u t r i e n t / g r a m excreta X c o n c e n t r a t i o n of dietary C r 2 0 3 -r c o n c e n t r a t i o n of e x c r e t a C r 2 0 3 ) X 100.

95

**Significant a t P < . 0 1 .

'Significant at P<.05.

Grain Autoclaving time Grain X autoclaving time Penicillin Grain X penicillin Autoclaving time X penicillin Grain X autoclaving time X penicillin Error

19.4 29.76

2 60

8.6

1222.0** 812.5** 70.9

4738.9** 177.4**

Feed intake

.02

.068

1.1

.09

31.17** .58** .29** 7.05** 4.22**

Feed/gain

8.65

945.2** 284.5** 15.6

4.7 1.7

6605.3**

Weight gain

.11

1.2

2.2

r

2

31

D re

Summary of analysis o Mean squtare

3.83 2.93 4.34 3.10 4.51 3.31 2.34 2.27 2.47 2.24 2.46 2.33

Feed/gain

19.3 28.7 17.8 30.3 17.5 29.2 41.9 43.3 41.8 45.6 40.3 44.9

(B.)

(a\

Weight gain

Response c

on the performance of chi

76.0 86.5 77.5 93.6 78.1 96.5 98.1 98.3 103.2 101.8 99.0 105.0

Feed intake

1 2 2 1 1 2

df

0 200 0 200 0 200 0 200 0 200 0 200

(mg/kg diet)

(min)

0 0 10 10 30 30 0 0 10 10 30 30

Penicillin

Autoclaving time

Source of variation

SE

Wheat Wheat Wheat Wheat Wheat Wheat

Rye Rye Rye Rye Rye Rye

Grain

Treatment

TABLE 4. The effect of autoclave treatment and penicillin supplementation

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TREATMENTS AND NUTRITIONAL VALUE OF RYE

The addition of freeze-dried or heat-dried water extracts to the wheat-based diets had variable effects on the different response criteria. The freeze-dried and heat-dried extracts added to the wheat-based diet reduced feed intake (21%, P<.01; 22%, P<.01), weight gain (23%, P<.01; 22%, P<.01), and feed efficiency (19%, P<.01; and 14%, P<.05), respectively. Amino acid digestibility was also reduced (8%, P<.01) when the freeze-dried extract was added to the wheat diet. Other response criteria were not affected (P>.05) by the addition of the two extracts to the wheatcontaining diet. In all cases the performance of birds fed the wheat diet plus either extract was

depressed (P<.05 or P<.01), but only feed intake was reduced to the level obtained when rye was fed. Feed intake, weight gain, and feed:gain values also tended to be intermediate to those obtained when either cereal was fed alone. The other values tend to be similar to those for birds fed the wheat-based diet. Both water extracts, when added to wheat diets, gave watery and sticky feces similar to those of rye-fed birds. Penicillin supplementation as shown in the footnotes of Table 5 improved all response criteria (P<.01). The interaction of grain component X penicillin level (P<.05) (footnotes, Table 5) demonstrated that dietary penicillin improved feed intake and weight gain to a much greater degree in birds fed diets containing rye, extracted rye, or freeze-dried rye extract, compared to those fed a wheat diet. Individual amino acid digestibilities were affected by water extraction of rye (Table 6). The digestibility of every amino acid was lower in the rye as compared to wheat-fed birds, with differences in percentage points ranging from 7 (leucine, phenylalanine, and proline) up to 16% (threonine and tyrosine). Extraction of rye improved (P<.05) the digestibility of all amino acids except for arginine and aspartic acid. However, only the digestibilities of alanine, histidine, leucine, and proline were similar to those observed in the wheat diets. In addition, the digestibilities of amino acids in birds fed the extracted rye plus the freeze-dried extract were either similar (P>.05) or higher (P<.05) than the values obtained with the rye diet. The heat-dried extract was less potent than the freeze-dried extract in depressing the digestibility of amino. acids. When the heat-dried extract was added to the wheat containing diet only the digestibilities of arginine, isoleucine, pheylalanine, threonine, tyrosine, and valine were lower (P<.05) than those of the wheatfed birds. In contrast, in the presence of the freeze-dried extract, all amino acids except aspartic acid, proline, serine, and threonine were depressed (P<.05) relative to the values obtained with wheat. Experiment 3. The results (Table 7) showed that feed consumption of the rye-fed birds was not improved by heat or water treatment. Soaking of nonautoclaved rye for 8 or 22 hr, respectively, improved weight gains by 15 (P>.01) and 25% (P<.01) and feed conversion efficiencies by 10 (P>.01) and 17% (P<.01) and produced less watery and sticky droppings

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interaction of grain X autoclave time X penicillin (P<.01) for dry matter retention indicated a reduced effectiveness of penicillin when 30 min autoclaved rye was fed. Experiment 2. Treatment means and a summary of analysis of variance are presented in Table 5. The grain component (average of two means with 0 and 200 ppm penicillin) had significant (P<.01) effects for all the response criteria. Birds fed unextracted rye had poorer feed intake (-18%), weight gain (-40%), feed conversion efficiency (—38%), retention of dry matter (-10%) and protein (-21%), and digestibility of total amino acids (—11%) and fat (-38%) than wheat-fed birds. The extraction of rye with water had no effect on feed intake (P>.05), but it improved weight gain (22%, P<.01), feed conversion efficiency (21%, P<.01), retention of dry matter (10%, P<.01) and protein (26%, P<.01), and the digestibilities of total amino acids (11%, P<.01) and fat (45%, P<.01) compared to rye-fed birds. However, feed intake (P<.01), weight gain (P<.01), feed:gain ratio (P<.05), and fat digestibility (P<.05) were inferior to results obtained with the wheat-fed birds. Noteworthy was the observation that the growth and feed conversion efficiency were similar with extracted rye and wheat plus rye extract. Extraction of rye was associated widi increased spillage resulting in reduced feed intake, probably because of the pulverization of rye during the extraction procedure. Addition of the freeze-dried extract to the extracted rye depressed almost all the response criteria, but only chick growth and feed-to-gain ratio were similar to that from nonextracted rye. This extract when added to extracted rye increased the stickness and wetness of the droppings and increased spillage further.

97

5 1 5 36

Grain c o m p o n e n t Penicillin Grain c o m p o n e n t X penicillin Error 1049** 638** 64* 22.1

1417** 867** 288* 78.0

2.9aA 2.1CC 2.3bBC 2.7»A 2.5bB 2.4bBC .06

Feed/gain

.6427** .3979** .0450 .0252

Feed/gain 50.8** 18.1** 3.6 3.0

Dry matter retention

Mean square

Summary of analysis of variance

61.lbB 68.0aA 67.0aA 65.7"A 66.0aA 67.7aA .6

Dry matter retention

Response criteria

1.

47

38. 47. 47. 48. 44.

Pro rete

of chicks fed rye or wheat based diets with o

Digestibility of total amino acids except glycine, t r y p t o p h a n , and sulfur-containing amino acids.

Not corrected for endogenous or metabolic contributions.

•Significant at P < . 0 5 . ••Significant at P < . 0 1 .

3

2

extract.

abc ABC ' Means not sharing a c o m m o n letter within each column differ significantly at P < . 0 5 (lower case) or P < . 0 1 (capital). Values cillin). The average values for birds fed diets with and w i t h o u t penicillin were: 149.2 vs. 140.6 g for feed intake, 63.7 vs. 55.4 g for weig matter retention, 4 7 . 0 vs. 44.2% for protein retention, 77.1 vs. 75.6% for amino acid digestibility and 80.9 vs. 69.5% for fat digestibility with or w i t h o u t penicillin and containing the following grain components were: 148.4 vs. 126.4 for rye, 165.9 vs. 169.4 for wheat, 139. plus freeze-dried extract, 158.3 vs. 141.4 for wheat plus freeze-dried extract, and 143.9 vs. 152.5 for wheat plus heat-dried extract. The c vs. 78.6 for wheat, 63.9 vs. 53.2 for extracted rye, 53.6 vs. 46.1 for extracted rye plus freeze-dried extract, 65.6 vs. 57.1 for wheat plus

df

Weight gain

Feed intake

48.2 C C 80.1aA 58.6bB 46.9cC 61.4bB 62.4bB 1.66

137.4cCB aA

167.7 133.7 C C 132.6cC 149.9bB 148.2t>B 3.12

Weight gain

of rye on the performance

Feed intake

Source of variation

Rye Wheat Extracted rye (ER) ER + freeze-dried extract Wheat + freeze-dried extract Wheat + heat-dried extract SE

Grain c o m p o n e n t

Test ingredients

TABLE 5. The effect of water extracts

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TREATMENTS AND NUTRITIONAL VALUE OF RYE

99

compared to untreated rye. In contrast, soaking the autoclaved rye did not improve chick performance. Better (P<.01) performance was obtained in all cases with the wheat than the rye fed chicks. The results of viscosity measurements (Table 8) showed that the water extract from rye grain was more than double the viscosity of the extract from wheat grain. Also the viscosity of the extract from nonautoclaved rye was more rapidly reduced (P<.01) with time compared to the other rye extracts.

m eg

&» v a .e a

Is

rt l> rt t> rt V 02 S W [i]

S

I

fi

Moran et al. (1969) reported that autoclaving of rye (121 C for 15 min) depressed its metabolizable energy and feed conversion efficiency. However, Misir and Marquardt (1978b) showed the autoclave treatment of rye for 10 or 30 min improved the weight gain of chicks as a result of increased feed intake compared to untreated rye but did not affect feedigain ratio. The current study also showed that autoclaving did not destroy the antigrowth factor in rye. This treatment, however, depressed nutrient utilization more in the rye than in the wheat-fed chicks as indicated by the grain X autoclaving time interaction for feed conversion efficiency (P<.01) and dry matter retention (P<.05). This same interaction for fat digestibility (P>.05) showed that autoclaving for 10 or 30 min, respectively, depressed the digestibility of fat by 19 and 22% in rye but only by 9 and 7% in the wheat-fed chicks. The poorer utilization of autoclaved rye tended to be compensated for by an increased feed intake (Table 4). It is not possible on the basis of the data presented in the current study to establish if the greater depression in the utilization of nutrient following autoclave treatment could be simply ascribed to a greater adverse thermal effect on nutrients per se or to a protective effect of heat on the antinutritional factor in rye. Autoclave treatment may inactivate endogenous enzymes that degrade part of the antinutritional factor. The antinutritional factor has been found to be composed of the water-soluble and water-insoluble pentosans, which are highly viscous polysaccharides (Antoniou and Marquardt, 1981; Antoniou et al, 1981). Endogenous enzymes may be involved in pentosan degradation, because the viscosity of water extracts from autoclaved rye was not depressed with time whereas a

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DISCUSSION

ANTONIOU AND MARQUARDT

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TABLE 7. Effect of autoclave treatment and water soaking on the performance of chicks (Experiment 3) Response criteria Test ingredient

Feed intake

Nonautoclaved rye Nonautoclaved rye, soaked 8 hr Nonautoclaved rye, soaked 22 hr Autoclaved rye Autoclaved rye, soaked 8 hr Autoclaved rye, soaked 22 hr Wheat SE

75.0 a 78.4 a 79.0 a 75.4 a 75.8 a 77.9 a 96.9b .97

Weight gain

Feed/gain

— (%)-

' ' c Means within each column not sharing a common superscript differ significantly at P<.01.

TABLE 8. Effect of,autoclave treatment and incubation time on the viscosity of rye extracts (Experiment 3) Viscosity1 Heat treatm ent Nonautoclaved rye 10 min autoclaved rye 20 min autoclaved rye 40 min autoclaved rye Nonautoclaved wheat 2 Distilled water 2 a

Ohr 181 ± . 5 a 184 ± 0 a 191 ± . 5 a 171 ± l a 85 ± .5 83 ± 0

14 hr 140 ± .5b 172 ± l a 187 ± 0 a 169 ± .5a 83 ± .5 83 ±0

' Means ± SE not sharing a common superscript letter differ significantly at P<.01.

1

Viscosities were determined as outflow time (sees) at 0 and 14 hr after the extracts were prepared.

2

Values ± SE not included in the statistical analysis.

marked viscosity depression occurred in the case of extracts from non-autoclaved rye (Table 8). The results of Experiment 3 also showed that the reduced viscosity of rye extracts was associated with reduced antinutritional activity in the rye-fed chicks. In a similar study, Gohl et al. (1978) reported that autoclaving of the grain of certain barley varieties increased their antinutritional activity when fed to chicks because heat destroyed the glucanase enzymes. Glucanases are responsible for partial degradation of the highly viscous /3-glucan, which was shown to be the antigrowth factor in barley. The results of the current experiments would suggest that autoclave treatment may be a useful preliminary step in studies designed to isolate a biologically active antinutritional factor from rye. The growth depression in Experiment 2

confirmed the presence of an antinutritional, water-soluble factor in rye grain (Fernadez et al, 1973). The current study also demonstrated that the depression of growth when this factor was added to wheat-based diets was attributed not only to the reduced feed palatability but also the poor digestion and absorption of nutrients. The poor palatability and digestibility may be ascribed to the sticky and viscous properties of the antigrowth factor. It may be hypothesized that penicillin supplementation of diets that contained rye, extracted rye, or freeze-dried extract improved nutrient digestibility by suppression of the adverse microflora. The increased population of intestinal microflora presumably thrive on the unabsorbed nutrients, thereby causing a further reduction in the availability of nutrients to the host animal (Marquardt et al., 1979).

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a

4.10 b 3.69 b c 3.41 c 4.23b 4.26 b 4.10 b 2.6 l a .132

18.5 a 21.3ab 23.2 b 17.9 a 17.8 a 19.1 a 37.4 C .75

TREATMENTS AND NUTRITIONAL VALUE OF RYE

Although twice extracted rye improved chick performance, the efficiency of feed conversion, weight gain, and fat digestibility of birds fed extracted rye was still inferior to that of chicks fed comparable wheat-based diets. This could be attributed not only to the reduced feed intake resulting from the pulverization of extracted rye but also to the incomplete extraction of all of the antinutritional factor(s) from the rye grain. It has recently been shown (Antoniou and Marquardt, 1981; Antoniou et al., 1981) that the waterinsoluble pentosans also possessed antinutritional activity. These pentosans, which have properties similar to those of the soluble fractions, contribute significantly to the growth depressing activity of rye and probably were responsible in the current study for part of the antinutritional activity that was present in the extracted rye. The possibility that some destruction of the antigrowth factors occurred during extraction could not be excluded, because the addition of the extract to the extracted rye did not give chick performance equal to that of rye fed to chicks. The heat-dried extract was slightly less effective than the freeze-dried extract. This

would indicate that prolonged extraction at room temperature followed by heat-drying may reduce the antinutritional activity of pentosans. The improvement of growth, efficiency of feed utilization, and fecal condition of chicks fed raw water-soaked rye compared to chicks fed raw rye or autoclaved water-soaked rye may be attributed to the partial degradation of pentosans by endogenous enzymes with increasing soaking period. Microbial degradation of pentosans was not possible because of the presence of toluene in the aqueous solution. No improvement was observed with autoclaved rye that might be attributed to heat inactivation of the enzymes responsible for degradation of the antinutritional factor in rye. The observation that there was a close association between the performance of chicks fed nonautoclaved rye, which was soaked for different time periods, and the corresponding reduction in the viscosity of rye extracts (Tables 7 and 8) indicated that the high viscosity of rye may be responsible for its antinutritional properties. Holas and Hampl (1973a) demonstrated that the viscosity of rye doughs, which was associated with the soluble and insoluble pentosans (Holas and Hampl, 1973b), was drastically reduced during the leavening procedure as a result of pentosan degradation by endogenous pentosanases, first isolated by Preece and MacDougall (1958). The current study showed that rye grain contains a heat-resistant, water-extractable, sticky, and hydroscopic antigrowth factor giving highly viscous aqueous solutions. This factor probably includes the water-soluble pentosans. When added to wheat-based diets it depressed chick performance and resulted in watery and sticky droppings. The viscosity of the factor seems to interfere with the digestion and absorption of nutrients whereas its sticky and gummy properties reduce feed palatability. The performance of chicks fed twice-extracted rye is considerably improved, but it is still inferior compared to the wheat-fed birds. This indicates that part of the antigrowth factors (water-insoluble pentosans) are not water extractable. Endogenous enzymes present in rye may be responsible for degradation of the soluble factor (pentosans) during soaking as suggested by the improved performance of chicks fed soaked, nonautoclaved rye. ACKNOWLEDGMENTS

This investigation was supported by the Grains and Oilseeds Marketing Incentives

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The depression of digestibility of all nutrients, particularly of fat and amino acids, could be a more useful means for monitoring the activity of the antinutritional factor in rye than following the depression in nutrients retained. The greater sensitivity of the former procedure is illustrated in Table 5 where the addition of the freeze-dried extract to the diets based on wheat or extracted rye reduced total amino acid digestibility to a greater degree than the retention of protein (N X 6.25). In the current study, the amino acids voided in the excreta may be considered to represent only undigested amino acids as the urinary excretion of amino acids are negligible (O'Dell et al., 1960). Amino acid digestibility, therefore, can be readily determined by subtracting amino acid excretion from amino acid intake. Protein retention, however, can readily be estimated by subtracting protein (N X 6.25) excreted, which included amino acids, uric acid, and urea from protein intake. The excretion of uric acid and urea are greatly affected by growth rate and protein quality. The difference between dietary and excreta fat can also be used to estimate fat digestibility, as very little fat is excreted in the urine (Sell and McKirdy, 1963).

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Program, Department of Industry Trade and Commerce, Government of Canada, and by a Manitoba Department of Agriculture grant to the Department of Animal Science, University of Manitoba. The technical assistance provided by J. A. McKirdy and P. Mills was greatly appreciated. REFERENCES

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