The nutritive value of barley for monogastric animals and for ruminants as affected by artificial drying and alkali and anaerobic storage

Animal Feed Science and Technology, 15 (1986) 2 8 5 - - 2 9 9

285

Elsevier Science Publishers B.V., A m s t e r d a m - - P r i n t e d in The Netherlands

THE NUTRITIVE VALUE OF BARLEY FOR MONOGASTRIC ANIMALS AND FOR RUMINANTS AS AFFECTED BY ARTIFICIAL DRYING AND ALKALI AND ANAEROBIC STORAGE

R.M. BEAMES, R.M. T A I T , D.B. P R I N G L E * and B.D. OWEN

University of British Columbia, Department of Animal Science, Vancouver, BC V6T 2A2 (Canada) (Received 16 J u l y 1985; a c c e p t e d for publication 28 F e b r u a r y 1986)

ABSTRACT Beames, R.M., Tait, R.M., Pringle, D.B. and Owen, B.D., 1986. The nutritive value of barley for monogastric animals and for r u m i n a n t s as affected by artificial drying and alkali and anaerobic storage. Anita. Feed Sci. Technol., 15: 285--299. Six e x p e r i m e n t s were c o n d u c t e d . In the first three, barley grain was either field-dried and harvested at 89% DM or harvested as high-moisture barley with 67% DM. The highmoisture barley was stored either anaerobically or artificially dried. Straw from the highmoisture barley was allowed to dry in the field and then stored. Straw f r o m the fielddried barley was also retained. Sheep were used to measure the digestibility of the three types of barley in E x p e r i m e n t I and the two types of straw in E x p e r i m e n t 2. In the third e x p e r i m e n t , rats were used to measure true protein digestibility, biological value and net protein utilization of the three types of barley. In E x p e r i m e n t s 4 and 5 barley was reconstituted and stored anaerobically or treated with a m m o n i a or sodium h y d r o x i d e and stored, and t h e n evaluated with sheep and rats. In E x p e r i m e n t 6, the loss of a m m o n i a on exposure of a m m o n i a - t r e a t e d grain to air was measured. The time of harvest o f physiologically mature barley had little effect on its p r o x i m a t e chemical c o m p o s i t i o n or on its nutritive value for sheep. The nutritive value o f straw, regardless of t i m e of harvest, was so low that the small differences in utilization were of limited nutritional consequence. With rats, although the drying of barley either in the field or artificially had no effect on dry m a t t e r digestibility, it did improve N retention. Alkali t r e a t m e n t of r e c o n s t i t u t e d barley had no effect on N r e t e n t i o n in sheep; however, the route of e x c r e t i o n was m o d i f i e d by s o d i u m h y d r o x i d e t r e a t m e n t . With rats, s o d i u m h y d r o x i d e t r e a t m e n t i m p r o v e d dry m a t t e r digestibility, but m a r k e d l y reduced N digestibility, biological value and N r e t e n t i o n ; a m m o n i a t r e a t m e n t also i m p r o v e d dry m a t t e r digestibility, but had no effect on N utilization parameters; r e c o n s t i t u t i o n reduced biological value. Results o b t a i n e d with the a m m o n i a - t r e a t e d r e c o n s t i t u t e d barley indicated that the a m m o n i a is largely c o n t a i n e d in the water and is rapidly and almost c o m p l e t e l y lost on exposure of the grain to air. This loss is not o n l y wasteful, but reduces initial animal acceptability.

*Present address: R i t c h i e - S m i t h Feeds Inc., A b b o t s f o r d , BC, Canada

0377-8401/86/$03.50

© 1986 Elsevier Science Publishers B.V.

286 INTRODUCTION

In many parts of the world, particularly where the growing season is short, early frosts or rain may interfere with the harvesting of grain at the normal time, when moisture content is below 17%. Although the nutritive value of grain may not be greatly affected by frosting (Bell, 1958), the reduction in yield as a result of wet conditions at time of harvesting can be substantial. The greater assurance of completing the harvest and maximizing returns by harvesting early makes such a practice economically attractive. However, grain harvested early contains a high level of moisture and, if stored under aerobic conditions, would spoil. Brooker et al. (1974) have quoted 11--13% as the maximum moisture content for satisfactory aerobic storage, although an exact level of moisture for safe storage cannot be stated, because losses are a direct function of temperature and relative humidity (Haward et al., 1974). High-moisture grain can be stored by controlling the environment (Hyde, 1974), e.g. sealed silos or pits, or by the addition of chemicals such as sodium hydroxide (0rskov and Greenhalgh, 1977), ammonia (Laksesvela, 1981) and organic acids (Jones et al., 1974). Both sodium hydroxide and ammonia have been shown to be effective in controlling microbial proliferation in moist grain (Bothast et al., 1975) and have improved fibre digestibility in ruminants (0rskov et al., 1979). However, sodium hydroxide-treated grain is difficult to handle and seriously reduces protein utilization in the monogastric animal (Pringle et al., 1983). The effect of ammonia preservation on utilization by monogastric animals appears not to have been investigated. This paper supplements results reported earlier (Pringle et al., 1983) on barley preserved with acid and with sodium hydroxide. The experiments were designed to investigate differences in nutritive value between grain harvested at a high moisture content and then dried, or preserved with sodium hydroxide or ammonia and field-dried grain either unprocessed or reconstituted and stored anaerobically. These measurements were made in sheep and rats, with measurements also made with sheep on the straw produced at the two times of harvest. Ammonia retention in ammonia-treated grain after exposure to the atmosphere was also measured. M A T E R I A L S AND METHODS

A total of six experiments was conducted, the first three with barley grain and straw from the experimental plots of the Field Crops Research Branch, Alberta Agriculture, Lacombe, Alberta and the second three with barley grain of unknown origin. From the Lacombe plots, every alternate swathe was harvested as highmoisture barley at 67% dry matter. The swathes were immediately combined and half of the grain sealed in two plastic-lined 200-1 drums with airtight lids. The other half of the high-moisture barley was passed through

287 gas-fired driers. This was designated artificially~iried barley. The remaining grain from these experimental plots was allowed to dry in the field for a further three weeks to 89% DM and was then harvested in a conventional manner. This was designated field
Experiment 1. Digestibility and nitrogen retention of Lacombe barley grain by sheep In an unbalanced randomized block design, 6 Dorset Horn ewe lambs of 40 kg average initial bodyweight were used over 4 periods to compare the utilization of barley stored for 4 months in 4 different ways. With this design, each ewe received each of the 4 treatments, which were high-moisture barley, artificially-dried barley, field
288

Experiment 2. Digestibility of Lacombe barley straw by sheep Twelve Dorset Horn ewe lambs of 40 kg average initial bodyweight were randomly divided into two groups of 6, with one group receiving a diet of high-moisture straw and the other group a diet of field-dried straw. The only supplement to the straw was 10 g day -~ of the same trace-mineralized salt as used in Experiment 1. Feeding was twice daffy. All sheep were kept in individual metabolism cages, with an adaptation period of 14 days and a collection period of 10 days. Faeces were collected and processed in the same w a y as in Experiment 1. Apparent digestibility of dry matter, organic matter, acid detergent fibre and nitrogen was measured.

Experiment 3. Evaluation of protein quality of Lacombe barley with rats This experiment was designed to compare nitrogen utilization and dry matter digestibility b y rats of barley which had been field~lried, harvested as high-moisture barley and either artificially
Experiment 4. Digestibility and nitrogen retention in sheep fed reconstituted alkali-treated whole barley F r o m 600 kg of barley (88% DM) obtained from a commercial supplier, 10 kg was placed in each of 60--23-1 polyethylene paris, with locking airtight lids, each fitted with a bunsen valve; 2.61 1 water was added to each pail. The pails were shaken and inverted daffy for a week to p r o m o t e even and complete absorption of water. The pails were then divided into four treat-

289 ments: (1) left in the reconstituted form at 70% DM; (2) sodium hydroxidetreated barley (65.1% DM); a 30% w/w aqueous solution of sodium hydroxide, which was allowed to cool after preparation, was added to give a final concentration o f 32 g sodium hydroxide kg -~ reconstituted barley {air dry basis); this was t h e n stored aerobically in 200-1 plastic-lined drums; (3) a m m o n i a added at a concentration of 1% (w/w); (4) ammonia added at a concentration of 3% (w/w). This ammonia-treated grain was stored in gastight containers until used. All grain was kept for 1 4 - 2 1 days before being used. Twelve Dorset Horn ewe lambs of 35--45 kg bodyweight were used in a completely randomized design to measure digestibility and nitrogen balance, with the diets consisting solely of the four types of reconstituted whole barley with 6 observations per treatment. Each ewe was stabilized at a steady intake of 600--700 g DM day -1 of whole reconstituted barley. Feeding and collection techniques were identical to those described in Experiment 2, with two exceptions, viz. each daily feed allowance of ammoniated barley was exposed to the atmosphere for 1 day before feeding, because of previous observations of poor acceptance if this was not done. Trace mineralized salt was n o t provided with the sodium hydroxide-treated barley, although all sheep had access to an iodized salt block. In the measurement of DM of the ammonia-treated barley, ammonia was lost. By measuring N content before and after drying, a correction was made for this loss.

Experiment 5. Nitrogen balance with rats fed reconstituted alkali-treated barley Dry matter digestibility, TD, BV and NPU, were measured on untreated barley, reconstituted barley, sodium hydroxide-treated barley and barley treated with 1 and 3% ammonia, which were described in Experiment 4. All samples were freeze
Experiment 6. Ammonia retention o f reconstituted ammoniated barley One kg of barley (88% DM) was placed in each o f five 3-1 glass jars. Water was added to four o f the five jars to increase the moisture content of the

290 treatments to 12, 18, 24, 30 and 36%. The jars were then sealed with lids fitted with two valves; one for adding ammonia and the other with a small balloon attached to monitor ammonia addition. Ammonia was injected at a concentration of 3.41% w/w, DM basis in all 5 treatments. Jars were stored for one week with daily turning and then opened and analyzed immediately for N content. Subsequent analyses were made on samples taken from this grain which was exposed in a thin layer to air at approximately 19°C for 40 days. Humidity was not recorded.

Chemical and statistical analyses Moisture was determined on feed and faeces by drying in a forced-draught oven at 90°C to constant weight, except for the high-moisture barley used in Experiments 1, 2 and 3, where the grain was dried to constant weight in a freeze dryer at 7 u Hg and -60°C. Nitrogen was determined by the macro Kjeldahl method of the Association of Official Analytical Chemists (1980). In preparation for analysis, sheep faeces were dried at 80°C, rat faeces were homogenized in the wet form after storage at -20°C, while ammoniated barley (5 g) was placed immediately after sampling into a Kjeldahl flask containing 50 ml concentrated H2SO4. Ash was analyzed by the Association of Official Analytical Chemists (1980) method while acid-detergent fibre was measured according to the method of Waldern (1971). Where statistical analyses were performed, the results were subjected to analysis of variance using the programme of Bjerring et al. (1975), with means compared by the Student Newman Keuls' test. RESULTS

Experiment I The chemical composition of the barley is given in Table I. Dry matter content of the high-moisture barley prior to storage was 67%, but after 4 months storage, it had dropped to 56%. Acid~letergent fibre content of the high-moisture barley was slightly higher than that of the other types of barley. Other constituents showed little variation between types. Digestibility and N retention data for the sheep are presented in Table II. Dry matter digestibility of reconstituted barley was significantly higher than that of artificially-dried barley, but no different from values obtained with field~lried and high-moisture barley. Organic matter digestibility of reconstituted barley and high-moisture barley was significantly higher than that of artificially
291 TABLEI Chemical composition of Lacombe barley used in Experiments 1 and 3 which was harvested at a high moisture level and stored anaerobically or artificially-dried or allowed to field-dry before harvesting, with the last t y p e of grain also reconstituted Composition

Type of Barley

Dry matter (%) Ash (% DM) Acid-detergent fibre (% DM) Nitrogen (% DM)

High-moisture

Artificially- Field-dried dried

Reconstituted

56.4 ~ 4.0 11.9 2.3

88.8 3.8 10.8 2.2

71.0 3.0 10.6 2.3

87.6 4.1 10.6 2.3

1The high-moisture barley was divided into two portions for the rat experiment (No. 3) and removed earlier than the sample analysed here. Consequently dry matter percentages were different for that experiment (see text). TABLE II Digestibility and nitrogen retention by sheep in Experiment 1 of whole barley grain from Lacombe harvested and stored in four different ways Type of Barley

Digestibility {%) Dry matter Organic matter Acid-detergent fibre Nitrogen N retention (%)

SE of Mean

HighArtificially- Field-dried Moisture dried ~

Reconstituted

78.8 ab2 81.2 a 41.8 a 78.6 a 27.3 a

79.4 a 81.3 a 32.9 b 79.2 a 24.7 a

76.8 b 78.5 b 21.9 c 74.7 a 26.0 a

77.8 ab 79.9 ab 31.3 b 76.2 a 28.3 a

0.6 0.5 2.0 1.0 3.7

'Harvested as high-moisture barley and immediately dried. ~Means within rows with no common superscript letter are significantly different (P < 0.01).

Experiment 2 Chemical composition of high-moisture straw and field
292 TABLE III Composition, voluntary intake and apparent digestibility by sheep in Experiment 2 of straw from high-moisture and field-dried barley from Lacombe Origin of straw High-moisture grain Composition (%) Dry matter I Ash (% DM) Acid-detergent fibre (% DM) Nitrogen (% DM) Voluntary intake (g DM d a y - ' ) Apparent digestibility (%) Dry matter Organic matter Acid-detergent fibre Nitrogen

86.0 10.3 50.0 1.04 294

37.7 a~ 39.9 a 33.8 a 45.1 a

SE of mean Field-dried grain

86.0 8.7 54.2 0.76 256

32.8 b 35.8 b 34.1 a 10.7 b

1.0 1.2 1.6 2.6

'Straw from high-moisture grain was dried in the field. Straw from field-dried barley was harvested at the time of harvesting the grain. 2Means within rows with different superscript letters are significantly different (P <

0.001). large effect of endogenous faecal N losses would make the apparent N digestibility values difficult to interpret.

Experiment 3 The chemical composition of the barley used in this experiment is given in Table I. Separate composite samples were removed from the tops and from the bottoms of the drums after 2 months of storage in contrast to the single composite sample taken after 4 months for the sheep experiment. Although ash, acid-detergent fibre and N values were similar to those listed for high-moisture barley in Table I, the dry matter contents were higher, being 74.7% for the sample from the top and 64.8% for the sample from the bottom. The results obtained with the rats (Table IV) indicated no differences in dry matter digestibility between treatments. However, there were differences in N utilization. TD values of field-dried barley and artificiallydried barley, of 89.0 and 89.1%, respectively, were slightly but significantly lower than the TD of high-moisture barley from the top (90.8%) and the high-moisture barley from the bottom (91.2%). However, the BV values for the two forms of dried barley were higher (82.2--82.3%) than the value

293

for high-moisture barley from the top, (77.6%) and from the b o t t o m (75.4%). The overall utilization of N, as measured by NPU, showed the value for high-moisture barley from the b o t t o m to be significantly lower than that of either field-dried or artificially
SE of mean

High-moisture

A p p a r e n t dry m a t t e r digestibility (%) True protein digestibility (TD) (%) Biological value (BV) (%) Net protein utilization (NPU) (%)

Artificially -1 dried

Fielddried

Top 2

Bottom 3

79.2 a4

79.6 a

80.0 a

79.7 a

0.5

90.8 a

91.2 a

89.1 b

89.0 b

0.4

77.6 b 70.5 ab

75.4 b 68.8 b

82.2 a 73.4 a

82.3 a 73.3 a

1.1 1.1

1Harvested as high-moisture barley and i m m e d i a t e l y dried artificially. 2Obtained f r o m t o p third o f 200-1 storage drum. 3Obtained f r o m b o t t o m third o f 200-I storage drum. 4Means within rows with no c o m m o n superscript letter are significantly different (P < 0.05 ).

TABLE V Chemical c o m p o s i t i o n of the r e c o n s t i t u t e d Experiment 4

alkali-treated barley used w i t h sheep in

M e t h o d of preservation

Composition Dry m a t t e r (%)1 Ash (% DM) Acid-detergent fibre (% DM) Nitrogen (% DM) 2

Reconstituted (RB)

R B + 3.2% NaOH

RB + 1% NH3

RB + 3% NH 3

70.5 2.59

65.1 7.66

69.8 2.37

70.4 2.21

8.10 2.14

6.64 1.95

5.67 2.60

5.24 3.25

1Corrected for N loss (see text). 2Determined o n whole moist grain at t i m e o f feeding.

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Experiment 4 The chemical composition of the whole barley stored anaerobically and preserved with sodium hydroxide or a m m o n i a is presented in Table V. Digestibility and N retention data obtained with sheep are presented in Table VI. Although all alkali-treated barleys gave higher mean values for both dry matter and organic matter digestibility than did reconstituted barley, only values for the 3% ammonia-treated barley were significantly higher. Nitrogen digestibility was significantly reduced as a result of sodium hydroxide preservation, but because of a concomitant reduction in urinary N o u t p u t , N retention was not affected. T A B L E VI N i t r o g e n r e t e n t i o n a n d digestibility o f r e c o n s t i t u t e d alkali-treated w h o l e barley determ i n e d w i t h s h e e p in E x p e r i m e n t 4 SE o f mean

Whole barley t r e a t m e n t s Reconstituted (RB)

RB + 312% NaOH

RB + 1% NH3

RB + 3% NH 3

Digestibility (%) Dry m a t t e r Organic m a t t e r Nitrogen

79.9 b i 82.0 b 79.9 a

82.0 ab 83.4 ab 62.1 b

81.9 ab 84.2 ab 78.6 a

83.6 a 85.9 a 83.3 a

0.7 0.7 1.4

N r e t e n t i o n (%)

26.5 a

26.3 a

25.2 a

26.2 a

2.4

1Means w i t h i n r o w s w i t h n o c o m m o n s u p e r s c r i p t l e t t e r are significantly d i f f e r e n t (P

< 0.05).

Experiment 5 Dry m a t t e r digestibility and protein utilization coefficients for alkalitreated barley determined with rats are presented in Table VII. Reconstitution had no effect on dry matter digestibility or TD, but significantly reduced BV from 75.7 to 71.2% with a similar reduction in NPU from 68.4 to 63.0%. Both TD and BV were severely reduced with sodium hydroxide t r e a t m e n t , with the result t h a t the NPU on this t r e a t m e n t was only 39%, in comparison to values in excess o f 59% for all other treatments. Reconstitution w i t h o u t any alkali t r e a t m e n t had no effect on dry matter digestibility or TD, but reduced BV to 71.2% from the 75.7% for the untreated barley. This resulted in a reduction in NPU from 68.4 to 63.0%. A m m o n i a t r e a t m e n t caused a slight but significant improvement in dry matter digestibility, but had no effect on TD, either with or w i t h o u t the correction for residual N. The corrections in Table VII were based on the assumption t h a t all the residual ammonia-N (0.02% for the 1% ammonia-

295 TABLE VII Dry m a t t e r digestibility a n d p r o t e i n u t i l i z a t i o n c o e f f i c i e n t s o f a l k a l i - t r e a t e d b a r l e y d e t e r m i n e d w i t h r a t s in E x p e r i m e n t 5 F o r m o f Barley

Apparent dry m a t t e r digestibility (%) True protein digestibility (TD) (%) Biological value ( B V ) (%) Net protein utilization ( N P U ) (%)

SE o f mean

Reconstituted (RB)

R B + 3.2% NaOH

RB + 1% NH3

RB + 3% NH3

82.0 c ~

86.8 a

83.9 b

84.6 b

82.5 c

0.3

88.4 a

71.6 b

90.1 a (89.9a):

90.9 a (90.4 a)

90.3 a

0.7

71.2 b

54.4 d

65.8 c

66.4 c

75.7 a

0.9

6 3 . 0 b(bc)

39.0 d

59.3 c (60.7 c)

60.4 c (64.1 b)

68.4 a

0.8

~Means w i t h i n rows w i t h n o c o m m o n

Untreated

s u p e r s c r i p t l e t t e r are s i g n i f i c a n t l y d i f f e r e n t (P

< 0.05). 2 N u m b e r s a n d s u p e r s c r i p t s w i t h i n b r a c k e t s r e p r e s e n t d a t a c o r r e c t e d f o r residual NH3-N as d e s c r i b e d in Materials a n d M e t h o d s .

treated barley and 0.05% for the 3% ammonia-treated barley) was absorbed and excreted in the urine. Although this assumption could not be proven with the present design, the relationship between these corrected NPU values and those of the other treatments would give a reasonable indication o f the effect of ammonia on the utilization of the N in the grain with these diets. The indications were that the ammonia itself was not utilized and that it had either no effect or a marginal negative effect on the grain N utilization.

Experiment 6 The results o f the measurements on the rate of loss o f ammonia from ammonia-treated barley of various moisture contents are given in Table VIII. The N content of the barley immediately after removal from the sealed jars showed little variation b e t w e e n treatments {4.3--4.8% N, DM basis) with the higher recoveries in the grain samples with a higher moisture content. If no losses had occurred, the N concentration in each jar w o u l d have been 5.1 g 100 g DM -1. Ammonia loss was greatest for all treatments in the first t w o days, with the loss being almost complete after 40 days. Ammonia loss closely paralleled water loss, indicating that the ammonia was dissolved in, and consequently lost with, the grain moisture.

296 TABLE VIII Residual moisture and N and estimated ammonia retention in ammonia-treated (3.41 g ammonia 100 g AD -1) reconstituted barley after a 1-week storage period and exposure to the air for varying periods (Experiment 6) Moisture content at time of addition (%)

12

18

24

30

36

Time required for application (rain) 1

33

8

7

5

3

Time ~ e r e x p o s u r e to air(d) 0 2 4 7 40

Weightlo~ with oven drying(% of AD) 16 9 9 9 9

20 10 10 10 9

25 11 11 10 9

32 13 11 10 9

0 2 4 7 40

Ni~o~n(%ofDM) 4.52 4.3 4.3 3.3 2.9 2.8 3.2 2.8 2.7 3.1 2.7 2.6 2.7 2.5 2.4

0 2 4 7 40

Retention ofadded ammonia(%) 78 71 71 82 36 21 18 14 32 18 14 11 28 14 11 7 14 7 3 3

4.6 2.7 2.6 2.5 2.4

38 15 12 11 9 4.8 2.6 2.6 2.5 2.4 89 11 11 7 3

~As determined by balloon method (see Materials and Methods). 2100% retention would give a value of 5.1. DISCUSSION I n t h e first t h r e e e x p e r i m e n t s , t h e b a r l e y was f r o m L a c o m b e a n d was e i t h e r h i g h - m o i s t u r e ( m e a n 67% DM), field~iried ( m e a n 87.6% DM) or h i g h - m o i s t u r e b a r l e y w h i c h was artificially dried at t h e t i m e o f harvest ( m e a n 8 8 . 8 % DM). Because t h e b a r l e y was h a r v e s t e d f r o m small experim e n t a l plots, 200-1 plastic-lined sealed d r u m s w e r e used f o r storage. Differences in m o i s t u r e c o n t e n t o f t h e h i g h - m o i s t u r e b a r l e y o n r e m o v a l f r o m t h e d r u m s f o r t h e rats a f t e r 2 m o n t h s o f storage ( m o i s t u r e u n c h a n g e d ) a n d f o r t h e sheep a f t e r 4 m o n t h s storage (a r e d u c t i o n t o 56% DM) w o u l d i n d i c a t e a greater f e r m e n t a t i o n in t h e latter case ( F o r b e s , 1 9 6 5 ) . H o w e v e r , t h e r e was n o e f f e c t o f t i m e o f sampling o n N c o n t e n t (g 1 0 0 g DM-1). Published r e p o r t s have i n d i c a t e d t h a t ensiled grain can have a higher soluble c r u d e p r o t e i n level t h a n dried grain ( M c K n i g h t et al., 1 9 7 3 ; J o n e s et al.,

297

1974) and that artificialdrying, especially at high temperatures, can reduce protein quality, although it does not affect N content. Although there was no significant effect of method of storage on N digestibility or retention with sheep, with rats the N P U values of both the artificially
298

urine to the faeces. On the other hand, sodium h y d r o x i d e addition had a serious adverse effect on b o t h the digestibility and biological value of protein for rats, which resulted in a 38% reduction in NPU. Similar results have been reported b y Pringle et al. (1983) with rats and Patterson (1984) with pigs. In summary, the time of harvest of physiologically mature barley was shown to have little effect on proximate analysis and on nutritive value for sheep. The nutritive value of straw, regardless o f time of harvest, was low and was considered to be of no importance in the determination o f optimal harvest time. Nitrogen balance measurements in rats demonstrated a slightly higher NPU value for dried grain than for high-moisture grain or reconstituted grain. Although this small difference would be of marginal economic significance, it does indicate an adverse effect of an increased moisture content on BV. Alkali treatment of barley did not improve its nutritional value for sheep, although the N from the added ammonia was utilized at a level similar to that o f the N from the grain. Sodium hydroxide severely reduced TD, BV and NPU of barley for rats, b u t ammonia treatment had no appreciable effect on the utilization of barley N. The improved dry matter digestibility b y rats of the sodium hydroxide-treated grain could have been accounted for by the absorption of the alkali per se. It was demonstrated that ammonia in ammonia-treated barley is loosely held and is lost with the moisture on exposure to air. ACKNOWLEDGEMENTS

The authors wish to express their appreciation to the Natural Sciences and Engineering Research Council of Canada for financial support, and to Dr. J. Helm and Mr. D. Dyson, Alberta Agriculture, for their co-operation in providing the barley and straw from their experimental plots. REFERENCES Association of Official Analytical Chemists, 1980. Official Methods of Analysis, 13th edn. Association of Official Analytical Chemists, Washington, DC. Bell, J.M., 1958. The effects of frost damage on the nutritional value of wheat. II. Feeding tests on various mill fractions. Can. J. Anita. Sci., 38: 1---9. Bjerring, J.H., Greig, M. and Halm, J.D., 1975. U.B.C. BMD 10V Analysis o f variance/ covariance. University of British Columbia Computing Centre, Vancouver, 32 pp. Bothast, R.J., Adams, G.H., Hatfield, E.E. and Lancaster, E.B., 1975. Preservation of high moisture corn: a microbiological evaluation. J. Dairy Sci., 58: 386--391. Brooker, D.B., Bakker-Arkema, F.W. and Hall, C.W., 1974. Principles of grain drying. In: Drying Cereal Grains, Avi Publishing, CT, pp. 1--21. Eggum, B.O., 1973. A study of certain factors influencing protein utilization in rats and pigs. Beret. Nat. Inst. Anita. Sci., Copenhagen, 4 0 6 : 1 7 3 pp. Forbes, J.L., 1965. Some observations on the hermetic storage of undried barley and its use in pig-feeding. Agric. Progress., 40: 55--67. Haward, W., Hunt, W.H. and Pixton, S.W., 1974. Moisture - - its significance, behaviour and measurement. In: Storage of Cereal Grains and Their Products (2nd edn), Assoc. Cereal Chemists, St. Paul, pp. 1--55.

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