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Yields, Compositions, and Nutritive Evaluation of Barley Silages at Three Stages of Maturity for Lactating Cows
Yields, Compositions, and Nutritive Evaluation of Barley Silages at Three Stages of Maturity for Lactating Cows C. E. POLAN, T. M. STARLING, J. T. HUBER, 1 C. N. MILLER, and R. A. SANDY
Department of Dairy Science, Virginia Polytechnic institute, Blacksburg Abstract
Five varieties of barley were harvested for forage in two consecutive years at three stages of maturity (bloom, milk, and dough). Dry matter content increased (P ~ .05) with stages of growth (22.0, 36.3, and 46.6%). Dry matter yields increased significantly between bloom and milk only. Heads accounted for 45.5% o£ the plant dry matter at the dough stage. Because o£ head growth, plant crude fiber decreased (32.1, 31.1, and 27.8%), nitrogen-free extract increased (49.2, 52.0, and 55.1%), and protein changed little with advancing maturity. Barley, ensiled at bloom, milk, and dough, was evaluated as a sole forage for lactating cows. An 18% protein concentrate was fed (1:3) and silage was offered ad libitum. Milk productiou was similar for the respective treatments (26.7, 26.5, 26.8 k g / day). Silage dry matter intake was least (P < .01) for bloom silage, which was reflected in the lowest (P < .05) body weight gains. For Days 57-63, dry matter (P ~ .01) and nitrogen-free extract (P < .05) digestibilities were lowest for d o u g h , and crude fiber digestibility was greatest (P ~ .01) for bloom silage. Fecal passage of barley grain in the dough group probably caused the decreased nitrogen-free extract digestibility. Molar percentages of acetate were lowest and propionate highest (P < .01) for the milk stage. Little information is available on the nutritive value of winter-grown small grains as ensiled forage for lactating cows. Morrison (8) considered them little better than timothy for hay, and fair to good for silage. ~Ieanwhile, in recent years yield potentials of small grains have markedly improved because o£ improved breeding and cultural practices. Barley is emerging as one of the highest yielding small grains. A number of the varieties are quite winter hardy. Furthermore, barley
matures earlier than wheat or oats. Therefore, it seems possible in milder climates to doublecrop corn (or sorghum) and barley, especially if the barley is harvested for forage prior to maturing. Small grains differ in time to harvest for silage to obtain maximum intake and nutrient utilization. McCullough and Sisk (7) reported superior intakes o£ wheat silage in an earlyheading stage compared with milk and dough. Based on lactation (5, 6) and digestibility data (12), the boot stage or soon thereafter was the most desirable stage to harvest oats for silage. Dry matter yields and proximate components of plant parts as influenced by stage of maturity of several barley varieties grown in Virginia are reported. Moreover, maturities were nutritionally evaluated in heavily lactating cows. Experimental Procedure
Agronomic experiment. The experiment was conducted at the Southside Virginia Research Station at Charlotte Court House. Five varieties of barley (Hordeum ~ulgare L.) were harvested at three stages o£ growth in 1964 and 1965. Two replications were used with a splitplot design; stages o£ growth were considered as whole plots and varieties as subplots. The three stages of growth were bloom, milk, and dough, and the five varieties were Wong, Penntad, James, Wade, and Rogers. Bloom stage was defined as the time when heads began to emerge; milk was when the endosperm was beginning to form but was still in a watery or milky stage; and dough was when the endosperm had solidified but could easily be dented. Each plot consisted of three rows 0.31 M apart and 6.1 M long. The harvested area was a 5.0 M section from the center row. The plots were fertilized with 5-10-10 at 673.3 kg per hectare when planted and were top-dressed with 28 kg per hectare of nitrogen in late February. Other production practices were those normally used for barley. Dry matter content of samples dried in a forage sample dryer at approximately 82 C was used to calculate plot yields. In 1964, a portion of each green sample was separated into leaves, stems, and heads. Chemical constituents in the total plant were calculated from analyses of the individual plant components.
Received for publication July 12, 1968. 1 Present address : Department of Dairy Science, Michigan State University, East Lansing. 1801
1802
POLAN, S T A R L I N G , H U B E R , M I L L E R , AND SANDY
Because differences attributable to varieties were small as contrasted to those for stage of growth, means and standard errors for the five varieties were combined. Ensilage. Barley (Rogers) was seeded October 1-10, 1965, with approximately 337 kg/ hectare of 10-20-20 fertilizer on Lodi loam, porous substratum soil. Barley was harvested during bloom (5/17), milk (5/28), and dough (6/8) stages for silage. Dry matter content on day of cutting was determined to he respectively 23.9, 30.7, and 45.6%. Bloom stage was allowed to wilt in the swath, whereas the other stages were harvested by direct-cut methods. All silages were preserved in conventional concrete-stave silos (3.0 by 0.2 M). Average dry matter contents of the respective maturities during feeding were 33.8, 26.4, and 37.8%. Animals. Eighteen Holstein cows were ranked according to milk production during a 2-wk preliminary period and divided into six outcome groups. One cow from each group was randomly assigned to one of three treatments. Daily milk production during a 2-wk preliminary period averaged 29.8 kg and ranged from 22.8 to 36.3 kg per cow. Treatment consisted of ad libitum consumption (5% in excess of appetite) of barley silage harvested either in the bloom, milk, or hard-dough stages of maturity as previously described. A concentrate mixture (18.1% crude protein containing 67% ground shelled corn, 26% soybean meal, 4% dried molasses, 2 1.75% dicalcinm phosphate, 1% salt, and 0.25% vitamin supplement s supplying 6,600 IU Vitamin A-palmitate/kg and 8,800 IU of vitamin D j k g ) was fed at the rate of 1 kg/3 kg of milk produced during the preliminary period. Milk production and intake data collected during the first 56 days are the basis for comparing treatments. For seven days, beginning with Day 57, an individual digestion trial was conducted by total collection. Feeds and feces were analyzed for proximate components by AOAC (1), except crude fiber, which was determined by the method of Whitehouse et al. (13). Rumen contents were sampled by stomach tube on the last day of the trial and analyzed for volatile fatty acids similarly to Baumgaxdt's method (2), using a Beckman GC-2A fitted with hydrogen flame detector. Two-day composite individual milk samples were collected during the preliminary period
and four times during treatment. Milk fat was analyzed by the Babcock method and crude protein and total solids determined according to Stone et al. (11); solids-not-fat were calculated by difference. Significance of treatment differences was determined by analysis of variance (9) and treatment means tested by Duncan's (3) multiple range. Results and Discussion
Barley yields and composition. Yield and composition of barley harvested at the various stages of maturity are summarized in Table 1. As expected, considerable yield differences existed between years; but the percentage increase with maturity in dry matter production was similar for both years. Although not statistically significant, a moderate increase in dry matter yield occurred beyond the milk stage. Considerable differences existed in dry matter content between years, which is apparently influenced by the availability of soil water. Usually, because of sufficient dry matter content, excellent preservation can be expected at the milk stage and beyond. Although dry matter yield increased only moderately beyond the milk stage, the yield of plant parts and distribution of plant composition were markedly altered (Table 1). Many of the composition changes occurring with maturity can be attributed to head development, with some diminution in both leaves and stems. Crude fiber percentage decreased in both heads and total plant. Crude fiber yield changed little with plant development beyond the milk, but because of increase in weight of heads, the percentage in the total plant was diluted. Crude protein content of the whole plant was lowest during the milk stage. At this point, 50% of the dry weight was in the stem, which analyzed just above 6.0% in crude protein. Plant crude protein increased about one percentage unit (dry basis) as heads increased beyond the milk stage. Although the protein content of the leaves was reduced by one-half from the bloom to the dough stage, this became relatively less important because the percentage dry weight from leaves was reduced from 23 to 12%. The changes in nitrogen-free extract content of the leaves and stems were relatively small compared to the heads. From bloom to softdough the head NFE increased nearly eight 2Nokako, courtesy of Arundel Feed Corpora- percentage units, with a significant increase at each stage of development. The abundance of tion, Baltimore, Maryland. 8Vitamins A and D, courtesy of Dawes Labora- NFE in the later stages of growth may be important in preserving direct-cut barley by entories, Inc., Ackworth, Iowa. J. DAII~" SCIENCE VOL. 51, NO. 11
BARLEY SILAGES T A B L E I.
1803
Total forage yield, yield of plant parts, and composition of barley harvested at various stages of growth. Bloom
Total dry matter (kg/hectare) 1964 1965 Average Dry matter content (%) 1964 1965 Average Plant parts (% of dry wt) ~ Leaves Stems Heads Crude fiber (%, dry basis) I Leaves Stems Heads Total Protein (%, dry basis) a Leaves Stems Heads Total Nitrogen-free extract (%, dry basis) a Leaves Stems Heads Total
Milk
Dough
6,213 ___209.6 4,732 _ 241.5 5,472 _ 267.7
7,792 _ 321.2 6,090 ~ 345.6 6,940 ~ 310.3
8,249 ___276.1 6,306 ± 273.1 7,277 _ 293.1
19.3 ± 0.48 24.7 _--+-0.70 22.0 ... 0.85
39.7 ~ 0.47 32.9 _--4-0.66 36.3 + 0.83
47.0 ± 0.34 46.3 ±. 0.85 46.6 ___ 0.36
22.8 _ 0.68 60.5 ± 0.67 16.8 ± 0.95
16.9 ± 0.77 50.8 + 1.34 32.2 ~ 1.85
11.8 ± 0.57 42.8 ± 0.86 45.5 ___ 1.11
26.3 36.1 25.4 32.1
± ± _ _
0.39 0.34 0.59 0.31
32.7 39.4 17.2 31.1
± ± ± _
0.48 0.50 0.58 0.54
36.1 40.9 13.4 27.8
+ 0.76 ± 0.82 ± 0.71 ___0.65
18.8 7.0 11.3 10.4
± + ± ±
0.42 0.39 0.25 0.35
12.4 6.2 13.8 9.7
± 0.52 _~ 0.26 ± 0.31 ± 0.28
9.8 6.3 15.1 10.7
... 0.44 -4- 0.54 ... 0.57 _ 0.42
41.1 49.8 58.4 49.2
± _ ± ±
0.29 0.47 0.49 0.28
41.2 48.4 63.7 52.0
± 0.34 _ 0.50 ± 0.83 ___ 0.56
43.0 46.7 66.2 55.1
± ± ± _
0.81 0.99 1.20 1.06
a Plant part separates and chemical analyses based on 1964 crop only. siling. E t h e r extract f o r the total plant changed little with m a t u r i t y (averaged 2.23%), and ash content declined (5.78, 5.05, and 4.04%). Stallcup et al. (10) r e p o r t e d that oats decreased in crude protein f r o m boot to milk and then changed little. Crude fiber was highest just p r i o r to milk stage, and N F E increased f r o m boot to milk to dough. Changes f o r proximate components of barley at these stages were similar to those for corn harvested at soft, medium, and hard dough as reported by H u b e r et al. (4). However, barley was slightly higher in protein and crude fiber but lower in N F E than corn. Corn protein changed little; crude fiber decreased 4.4% (barley 4 . 3 % ) ; and corn N F E increased 4.3% (barley 5.9%) with increasing maturity. P r o x i m a t e components of dough-stage barley were similar to corn in the soft-dough stage o f growth. A n i m a l studies. The effect of barley m a t u r i t y on intakes is shown in Table 2. Concentrate intake was based on milk production during the p r e l i m i n a r y period and was similar f o r all treatments; therefore, differences in total dry matter intake were due to silage consumption. D r y m a t t e r intakes of the more mature silages were nearly equal, both greater (P < .05) than the bloom silage. Silage dry m a t t e r content was similar f o r the wilted bloom and direct-cut, dough-stage silage. Better crop preservation was
a p p a r e n t f o r barley in the milk stage, presumably because the drier silage permitted more air to be ensiled, due to the hollow stems. H o w ever, the lower dry m a t t e r content of the milkstage silage m a y have resulted in a lower intake than if it had been wilted. The probable importance of dry matter content at harvest on dry m a t t e r intake was shown by H u b e r et al. (4). As corn silage dry matter percentage increased TABLE 2. Effect of stage of maturity of ensiled barley on intake, ~ milk production, milk composition, and body weight. Item
Stage of maturity Bloom Milk Dough
Silage dry matter (as fed) 33.8 ~ Silage intake (% body weight) 1.24 ~ Total intake (% body weight) 2.77 Milk (kg/day) 26.70 Milk fat (%) 3.36 Milk solids-notfat (%) 8.80 Milk protein ( % ) 2.91 Body weight gains (kg/day) 0.01 b
26.4 1.54 °
37.8 1.53 e
3.04 26.46 3.25
3.04 26.75 3.33
8.85 3.13
8.73 3.02
0.39 c
0.41 ~
Intake expressed on dry basis. Wilted prior to ensiling. b'eYalues not sharing a common superscript are significantly different (P < .05). J. DAIRY SCIeNCe., Von. 51, NO. ii
1804
POLAN, STARLING, HUBER, MILLER, A N D S A N D Y
from 25 to 30.3 and 33.3, dry matter intake as per cent of body weight increased from 1.81 to 1.90 to 2.00, a significant trend (P < .05). Intake of barley silage at best was lower than that reported for corn. However, cows were consuming high levels of concentrate (1.5% of body weight) to maintain milk production, and the study was conducted during the hot summer months. Milk production was remarkably similar between the various groups for the total treatment period (Table 2). A high level of production was maintained for the 8-wk period. Milk fat test increased sharply in all groups and averaged 111-118% of the pretreatment period. During the pretreatment period, cows had received grass silage and lush spring pasturage, which was probably conducive to some depression in milk fat per cent. Moderate increases for all groups also occurred in milk nonfat solids and protein. Weight gains of cows on milk and dough were significantly greater than those on bloom silage, which did not change during treatment. This response was associated with the greater dry matter intakes in the former groups. Digestion coefficients of proximate constituents are shown in Table 3. The percentage dry matter intake as concentrate for the bloom, milk, and dough groups was, respectively, 55.5, 48.2, and 49.7%. Concentrate provided relatively more dry matter in the bloom group, due to reduced silage intake. Dry matter (P < .01) TABLE 3. Effect of stage of maturity of ensiled barley on nutrient digestibility and rumen volatile fatty acids. Item
Bloom
Digestion coefficients (%) Dry matter 67.8 a Crude protein 62.9 Crude fiber 59.6 a Nitrogen-free extract 73.9 a'b'¢ Volatile fatty acids (m~/100 ml) 7.00 Acetate (molar %) 65.2~ Propionate (molar %) 17.5~ Butyrate (molar %) 14.5 Acetate :propionate 3.75 *
Stage of maturity Milk Dough
67.9 ~
64.2b
60.3 50.8b
61.9 50.4b
75.9~'c
70.8b'd
7.96
9.83
58.9b
62.0 a'b
21.9 b
16.6"
15.4
13.9
2.75 b
3.74"
a.b Values not sharing a common superscript axe significantly different (P < .01). o,d ( e < .05). J . DAIRY SeIENeS ¥-OL. 51, NO. 11
and N F E (P < .05) digestibility were lower in the hard-dough silage group. Throughout the trial, cows consuming hard-dough silage excreted a large portion of undigested grain, which probably caused the reduced digestibility of N F E . Molar ratio of acetate :propionate was less (P < .01) for the milk-stage silage than for the other treatments (Table 3), and was probably related to higher N F E and lower crude fiber digestibilities. From the duta presented in this paper, it is apparent that barley plants ensiled with the proper moisture content are a very adequate forage f o r lactating cows. Based on the proximate analysis, increased content of N F E and decreased fiber can be expected with increasing maturity. The data suggest that the crop should be ensiled not later than the earlydough stage to obtain optimal intake and digestibility of nutrients. Excellent crop preservation will normally result from direct-field harvesting of barley when in the milk or more advanced stages of growth.
Acknowledgments We express our sincere appreciation to the VPI Forage Testing Laboratory for proximate analyses and to Kenneth Williams, J. F. ¥ates, and Walter Shepherd for excellent care of the experimental animals.
References (1) Association of Official Agricultural Chemists. 1960. Official Methods of Analysis. 9th ed. Washington, D.C. (2) Baumgaxdt, B. R. 1964. Practical observations on the quantitative analysis of free volatile fatty acids (VFA) in aqueous solutions by gas-liquid chromatography. Dept. of Dairy Science, University of Wisconsin, Dept. Bull. 1. (3) Duncan, D. B. 1955. Multiple Range and Multiple ~ tests. Biometrics, 11 : t. (4) Huber, J. T., G. C. Graf, and R. W. Engel. 1965. Effect of maturity on nutritive value of corn silage for lactating cows. J. Dairy Sci., 48: 1121. (5) Martz, F. A., C. H. Noller, D. L. Hill, and M. W. Carter. 1959. Intake and value for milk production of oat silages ensiled at three stages of maturity and preserved with sodium metabisulfite. J. Dairy Sci., 42 : 1955. (6) McCullough, M. E., L. R. Sisk, and O. E. Sell. 1958. Influence of stage of maturity and of ground snap corn or sodium metabisulfite as preservatives on the feeding value of oat silage. J. Dairy Sci., 41: 796.
BARLEY SILAGES (7) McCullough, M. E., and L. R. Sisk. 1967. Influence of stage of maturity at harvest and level of grain feeding on intake of wheat silage. J. Dairy Sei., 50: 705. (8) Morrison, F. B. 1957. Feeds and Feeding. 22nd ed. Morrison Publishing Company, Ithaca, New York. pp. 371-372. (9) Snedeeor, G. W. 1956. Statistical Methods Applied to Experiments in Agriculture and Biology. 5th ed. Iowa State University Press, Ames. (10) Stallcup, O. T., R. R. Roberson, C. D. Looper, and R. L. Thurman. 1961. The influenee of stage of maturity on the nutritive value
1805
of oat forage. Arkansas Agr. Exp. Sta., Bull. 642. (11) Stone, W. K., M. C. Conner, and 1~. R. Thompson. 1964. Amounts, variations, and interrelations of the major milk constituents in individual f a r m deliveries. J. Dairy Sei., 47 : 502. (12) Thurman, R. L., O. T. Stallcup, J. L. Stephens, and N. E. Justns. 1957. When to harvest oats for hay and silage. Arkansas Agr. Exp. Sta., Bull. 586. (13) Whitehouse, K., A. Farow, and H. Shay. 1945. Rapid method for determining crude fiber in distillers dried grain. J. Ass. Offie. Agr. Chemists, 28: 147.
J. D~u~Y SCn~NC~, VOL. 51, NO. 11
Department of Dairy Science, Virginia Polytechnic institute, Blacksburg Abstract
Five varieties of barley were harvested for forage in two consecutive years at three stages of maturity (bloom, milk, and dough). Dry matter content increased (P ~ .05) with stages of growth (22.0, 36.3, and 46.6%). Dry matter yields increased significantly between bloom and milk only. Heads accounted for 45.5% o£ the plant dry matter at the dough stage. Because o£ head growth, plant crude fiber decreased (32.1, 31.1, and 27.8%), nitrogen-free extract increased (49.2, 52.0, and 55.1%), and protein changed little with advancing maturity. Barley, ensiled at bloom, milk, and dough, was evaluated as a sole forage for lactating cows. An 18% protein concentrate was fed (1:3) and silage was offered ad libitum. Milk productiou was similar for the respective treatments (26.7, 26.5, 26.8 k g / day). Silage dry matter intake was least (P < .01) for bloom silage, which was reflected in the lowest (P < .05) body weight gains. For Days 57-63, dry matter (P ~ .01) and nitrogen-free extract (P < .05) digestibilities were lowest for d o u g h , and crude fiber digestibility was greatest (P ~ .01) for bloom silage. Fecal passage of barley grain in the dough group probably caused the decreased nitrogen-free extract digestibility. Molar percentages of acetate were lowest and propionate highest (P < .01) for the milk stage. Little information is available on the nutritive value of winter-grown small grains as ensiled forage for lactating cows. Morrison (8) considered them little better than timothy for hay, and fair to good for silage. ~Ieanwhile, in recent years yield potentials of small grains have markedly improved because o£ improved breeding and cultural practices. Barley is emerging as one of the highest yielding small grains. A number of the varieties are quite winter hardy. Furthermore, barley
matures earlier than wheat or oats. Therefore, it seems possible in milder climates to doublecrop corn (or sorghum) and barley, especially if the barley is harvested for forage prior to maturing. Small grains differ in time to harvest for silage to obtain maximum intake and nutrient utilization. McCullough and Sisk (7) reported superior intakes o£ wheat silage in an earlyheading stage compared with milk and dough. Based on lactation (5, 6) and digestibility data (12), the boot stage or soon thereafter was the most desirable stage to harvest oats for silage. Dry matter yields and proximate components of plant parts as influenced by stage of maturity of several barley varieties grown in Virginia are reported. Moreover, maturities were nutritionally evaluated in heavily lactating cows. Experimental Procedure
Agronomic experiment. The experiment was conducted at the Southside Virginia Research Station at Charlotte Court House. Five varieties of barley (Hordeum ~ulgare L.) were harvested at three stages o£ growth in 1964 and 1965. Two replications were used with a splitplot design; stages o£ growth were considered as whole plots and varieties as subplots. The three stages of growth were bloom, milk, and dough, and the five varieties were Wong, Penntad, James, Wade, and Rogers. Bloom stage was defined as the time when heads began to emerge; milk was when the endosperm was beginning to form but was still in a watery or milky stage; and dough was when the endosperm had solidified but could easily be dented. Each plot consisted of three rows 0.31 M apart and 6.1 M long. The harvested area was a 5.0 M section from the center row. The plots were fertilized with 5-10-10 at 673.3 kg per hectare when planted and were top-dressed with 28 kg per hectare of nitrogen in late February. Other production practices were those normally used for barley. Dry matter content of samples dried in a forage sample dryer at approximately 82 C was used to calculate plot yields. In 1964, a portion of each green sample was separated into leaves, stems, and heads. Chemical constituents in the total plant were calculated from analyses of the individual plant components.
Received for publication July 12, 1968. 1 Present address : Department of Dairy Science, Michigan State University, East Lansing. 1801
1802
POLAN, S T A R L I N G , H U B E R , M I L L E R , AND SANDY
Because differences attributable to varieties were small as contrasted to those for stage of growth, means and standard errors for the five varieties were combined. Ensilage. Barley (Rogers) was seeded October 1-10, 1965, with approximately 337 kg/ hectare of 10-20-20 fertilizer on Lodi loam, porous substratum soil. Barley was harvested during bloom (5/17), milk (5/28), and dough (6/8) stages for silage. Dry matter content on day of cutting was determined to he respectively 23.9, 30.7, and 45.6%. Bloom stage was allowed to wilt in the swath, whereas the other stages were harvested by direct-cut methods. All silages were preserved in conventional concrete-stave silos (3.0 by 0.2 M). Average dry matter contents of the respective maturities during feeding were 33.8, 26.4, and 37.8%. Animals. Eighteen Holstein cows were ranked according to milk production during a 2-wk preliminary period and divided into six outcome groups. One cow from each group was randomly assigned to one of three treatments. Daily milk production during a 2-wk preliminary period averaged 29.8 kg and ranged from 22.8 to 36.3 kg per cow. Treatment consisted of ad libitum consumption (5% in excess of appetite) of barley silage harvested either in the bloom, milk, or hard-dough stages of maturity as previously described. A concentrate mixture (18.1% crude protein containing 67% ground shelled corn, 26% soybean meal, 4% dried molasses, 2 1.75% dicalcinm phosphate, 1% salt, and 0.25% vitamin supplement s supplying 6,600 IU Vitamin A-palmitate/kg and 8,800 IU of vitamin D j k g ) was fed at the rate of 1 kg/3 kg of milk produced during the preliminary period. Milk production and intake data collected during the first 56 days are the basis for comparing treatments. For seven days, beginning with Day 57, an individual digestion trial was conducted by total collection. Feeds and feces were analyzed for proximate components by AOAC (1), except crude fiber, which was determined by the method of Whitehouse et al. (13). Rumen contents were sampled by stomach tube on the last day of the trial and analyzed for volatile fatty acids similarly to Baumgaxdt's method (2), using a Beckman GC-2A fitted with hydrogen flame detector. Two-day composite individual milk samples were collected during the preliminary period
and four times during treatment. Milk fat was analyzed by the Babcock method and crude protein and total solids determined according to Stone et al. (11); solids-not-fat were calculated by difference. Significance of treatment differences was determined by analysis of variance (9) and treatment means tested by Duncan's (3) multiple range. Results and Discussion
Barley yields and composition. Yield and composition of barley harvested at the various stages of maturity are summarized in Table 1. As expected, considerable yield differences existed between years; but the percentage increase with maturity in dry matter production was similar for both years. Although not statistically significant, a moderate increase in dry matter yield occurred beyond the milk stage. Considerable differences existed in dry matter content between years, which is apparently influenced by the availability of soil water. Usually, because of sufficient dry matter content, excellent preservation can be expected at the milk stage and beyond. Although dry matter yield increased only moderately beyond the milk stage, the yield of plant parts and distribution of plant composition were markedly altered (Table 1). Many of the composition changes occurring with maturity can be attributed to head development, with some diminution in both leaves and stems. Crude fiber percentage decreased in both heads and total plant. Crude fiber yield changed little with plant development beyond the milk, but because of increase in weight of heads, the percentage in the total plant was diluted. Crude protein content of the whole plant was lowest during the milk stage. At this point, 50% of the dry weight was in the stem, which analyzed just above 6.0% in crude protein. Plant crude protein increased about one percentage unit (dry basis) as heads increased beyond the milk stage. Although the protein content of the leaves was reduced by one-half from the bloom to the dough stage, this became relatively less important because the percentage dry weight from leaves was reduced from 23 to 12%. The changes in nitrogen-free extract content of the leaves and stems were relatively small compared to the heads. From bloom to softdough the head NFE increased nearly eight 2Nokako, courtesy of Arundel Feed Corpora- percentage units, with a significant increase at each stage of development. The abundance of tion, Baltimore, Maryland. 8Vitamins A and D, courtesy of Dawes Labora- NFE in the later stages of growth may be important in preserving direct-cut barley by entories, Inc., Ackworth, Iowa. J. DAII~" SCIENCE VOL. 51, NO. 11
BARLEY SILAGES T A B L E I.
1803
Total forage yield, yield of plant parts, and composition of barley harvested at various stages of growth. Bloom
Total dry matter (kg/hectare) 1964 1965 Average Dry matter content (%) 1964 1965 Average Plant parts (% of dry wt) ~ Leaves Stems Heads Crude fiber (%, dry basis) I Leaves Stems Heads Total Protein (%, dry basis) a Leaves Stems Heads Total Nitrogen-free extract (%, dry basis) a Leaves Stems Heads Total
Milk
Dough
6,213 ___209.6 4,732 _ 241.5 5,472 _ 267.7
7,792 _ 321.2 6,090 ~ 345.6 6,940 ~ 310.3
8,249 ___276.1 6,306 ± 273.1 7,277 _ 293.1
19.3 ± 0.48 24.7 _--+-0.70 22.0 ... 0.85
39.7 ~ 0.47 32.9 _--4-0.66 36.3 + 0.83
47.0 ± 0.34 46.3 ±. 0.85 46.6 ___ 0.36
22.8 _ 0.68 60.5 ± 0.67 16.8 ± 0.95
16.9 ± 0.77 50.8 + 1.34 32.2 ~ 1.85
11.8 ± 0.57 42.8 ± 0.86 45.5 ___ 1.11
26.3 36.1 25.4 32.1
± ± _ _
0.39 0.34 0.59 0.31
32.7 39.4 17.2 31.1
± ± ± _
0.48 0.50 0.58 0.54
36.1 40.9 13.4 27.8
+ 0.76 ± 0.82 ± 0.71 ___0.65
18.8 7.0 11.3 10.4
± + ± ±
0.42 0.39 0.25 0.35
12.4 6.2 13.8 9.7
± 0.52 _~ 0.26 ± 0.31 ± 0.28
9.8 6.3 15.1 10.7
... 0.44 -4- 0.54 ... 0.57 _ 0.42
41.1 49.8 58.4 49.2
± _ ± ±
0.29 0.47 0.49 0.28
41.2 48.4 63.7 52.0
± 0.34 _ 0.50 ± 0.83 ___ 0.56
43.0 46.7 66.2 55.1
± ± ± _
0.81 0.99 1.20 1.06
a Plant part separates and chemical analyses based on 1964 crop only. siling. E t h e r extract f o r the total plant changed little with m a t u r i t y (averaged 2.23%), and ash content declined (5.78, 5.05, and 4.04%). Stallcup et al. (10) r e p o r t e d that oats decreased in crude protein f r o m boot to milk and then changed little. Crude fiber was highest just p r i o r to milk stage, and N F E increased f r o m boot to milk to dough. Changes f o r proximate components of barley at these stages were similar to those for corn harvested at soft, medium, and hard dough as reported by H u b e r et al. (4). However, barley was slightly higher in protein and crude fiber but lower in N F E than corn. Corn protein changed little; crude fiber decreased 4.4% (barley 4 . 3 % ) ; and corn N F E increased 4.3% (barley 5.9%) with increasing maturity. P r o x i m a t e components of dough-stage barley were similar to corn in the soft-dough stage o f growth. A n i m a l studies. The effect of barley m a t u r i t y on intakes is shown in Table 2. Concentrate intake was based on milk production during the p r e l i m i n a r y period and was similar f o r all treatments; therefore, differences in total dry matter intake were due to silage consumption. D r y m a t t e r intakes of the more mature silages were nearly equal, both greater (P < .05) than the bloom silage. Silage dry m a t t e r content was similar f o r the wilted bloom and direct-cut, dough-stage silage. Better crop preservation was
a p p a r e n t f o r barley in the milk stage, presumably because the drier silage permitted more air to be ensiled, due to the hollow stems. H o w ever, the lower dry m a t t e r content of the milkstage silage m a y have resulted in a lower intake than if it had been wilted. The probable importance of dry matter content at harvest on dry m a t t e r intake was shown by H u b e r et al. (4). As corn silage dry matter percentage increased TABLE 2. Effect of stage of maturity of ensiled barley on intake, ~ milk production, milk composition, and body weight. Item
Stage of maturity Bloom Milk Dough
Silage dry matter (as fed) 33.8 ~ Silage intake (% body weight) 1.24 ~ Total intake (% body weight) 2.77 Milk (kg/day) 26.70 Milk fat (%) 3.36 Milk solids-notfat (%) 8.80 Milk protein ( % ) 2.91 Body weight gains (kg/day) 0.01 b
26.4 1.54 °
37.8 1.53 e
3.04 26.46 3.25
3.04 26.75 3.33
8.85 3.13
8.73 3.02
0.39 c
0.41 ~
Intake expressed on dry basis. Wilted prior to ensiling. b'eYalues not sharing a common superscript are significantly different (P < .05). J. DAIRY SCIeNCe., Von. 51, NO. ii
1804
POLAN, STARLING, HUBER, MILLER, A N D S A N D Y
from 25 to 30.3 and 33.3, dry matter intake as per cent of body weight increased from 1.81 to 1.90 to 2.00, a significant trend (P < .05). Intake of barley silage at best was lower than that reported for corn. However, cows were consuming high levels of concentrate (1.5% of body weight) to maintain milk production, and the study was conducted during the hot summer months. Milk production was remarkably similar between the various groups for the total treatment period (Table 2). A high level of production was maintained for the 8-wk period. Milk fat test increased sharply in all groups and averaged 111-118% of the pretreatment period. During the pretreatment period, cows had received grass silage and lush spring pasturage, which was probably conducive to some depression in milk fat per cent. Moderate increases for all groups also occurred in milk nonfat solids and protein. Weight gains of cows on milk and dough were significantly greater than those on bloom silage, which did not change during treatment. This response was associated with the greater dry matter intakes in the former groups. Digestion coefficients of proximate constituents are shown in Table 3. The percentage dry matter intake as concentrate for the bloom, milk, and dough groups was, respectively, 55.5, 48.2, and 49.7%. Concentrate provided relatively more dry matter in the bloom group, due to reduced silage intake. Dry matter (P < .01) TABLE 3. Effect of stage of maturity of ensiled barley on nutrient digestibility and rumen volatile fatty acids. Item
Bloom
Digestion coefficients (%) Dry matter 67.8 a Crude protein 62.9 Crude fiber 59.6 a Nitrogen-free extract 73.9 a'b'¢ Volatile fatty acids (m~/100 ml) 7.00 Acetate (molar %) 65.2~ Propionate (molar %) 17.5~ Butyrate (molar %) 14.5 Acetate :propionate 3.75 *
Stage of maturity Milk Dough
67.9 ~
64.2b
60.3 50.8b
61.9 50.4b
75.9~'c
70.8b'd
7.96
9.83
58.9b
62.0 a'b
21.9 b
16.6"
15.4
13.9
2.75 b
3.74"
a.b Values not sharing a common superscript axe significantly different (P < .01). o,d ( e < .05). J . DAIRY SeIENeS ¥-OL. 51, NO. 11
and N F E (P < .05) digestibility were lower in the hard-dough silage group. Throughout the trial, cows consuming hard-dough silage excreted a large portion of undigested grain, which probably caused the reduced digestibility of N F E . Molar ratio of acetate :propionate was less (P < .01) for the milk-stage silage than for the other treatments (Table 3), and was probably related to higher N F E and lower crude fiber digestibilities. From the duta presented in this paper, it is apparent that barley plants ensiled with the proper moisture content are a very adequate forage f o r lactating cows. Based on the proximate analysis, increased content of N F E and decreased fiber can be expected with increasing maturity. The data suggest that the crop should be ensiled not later than the earlydough stage to obtain optimal intake and digestibility of nutrients. Excellent crop preservation will normally result from direct-field harvesting of barley when in the milk or more advanced stages of growth.
Acknowledgments We express our sincere appreciation to the VPI Forage Testing Laboratory for proximate analyses and to Kenneth Williams, J. F. ¥ates, and Walter Shepherd for excellent care of the experimental animals.
References (1) Association of Official Agricultural Chemists. 1960. Official Methods of Analysis. 9th ed. Washington, D.C. (2) Baumgaxdt, B. R. 1964. Practical observations on the quantitative analysis of free volatile fatty acids (VFA) in aqueous solutions by gas-liquid chromatography. Dept. of Dairy Science, University of Wisconsin, Dept. Bull. 1. (3) Duncan, D. B. 1955. Multiple Range and Multiple ~ tests. Biometrics, 11 : t. (4) Huber, J. T., G. C. Graf, and R. W. Engel. 1965. Effect of maturity on nutritive value of corn silage for lactating cows. J. Dairy Sci., 48: 1121. (5) Martz, F. A., C. H. Noller, D. L. Hill, and M. W. Carter. 1959. Intake and value for milk production of oat silages ensiled at three stages of maturity and preserved with sodium metabisulfite. J. Dairy Sci., 42 : 1955. (6) McCullough, M. E., L. R. Sisk, and O. E. Sell. 1958. Influence of stage of maturity and of ground snap corn or sodium metabisulfite as preservatives on the feeding value of oat silage. J. Dairy Sci., 41: 796.
BARLEY SILAGES (7) McCullough, M. E., and L. R. Sisk. 1967. Influence of stage of maturity at harvest and level of grain feeding on intake of wheat silage. J. Dairy Sei., 50: 705. (8) Morrison, F. B. 1957. Feeds and Feeding. 22nd ed. Morrison Publishing Company, Ithaca, New York. pp. 371-372. (9) Snedeeor, G. W. 1956. Statistical Methods Applied to Experiments in Agriculture and Biology. 5th ed. Iowa State University Press, Ames. (10) Stallcup, O. T., R. R. Roberson, C. D. Looper, and R. L. Thurman. 1961. The influenee of stage of maturity on the nutritive value
1805
of oat forage. Arkansas Agr. Exp. Sta., Bull. 642. (11) Stone, W. K., M. C. Conner, and 1~. R. Thompson. 1964. Amounts, variations, and interrelations of the major milk constituents in individual f a r m deliveries. J. Dairy Sei., 47 : 502. (12) Thurman, R. L., O. T. Stallcup, J. L. Stephens, and N. E. Justns. 1957. When to harvest oats for hay and silage. Arkansas Agr. Exp. Sta., Bull. 586. (13) Whitehouse, K., A. Farow, and H. Shay. 1945. Rapid method for determining crude fiber in distillers dried grain. J. Ass. Offie. Agr. Chemists, 28: 147.
J. D~u~Y SCn~NC~, VOL. 51, NO. 11