Relationships Between Stage of Maturity of the Corn Plant at Time of Harvest for Corn Silage and Chemical Composition1,2

Relationships Between Stage of Maturity of the Corn Plant at Time of Harvest for Corn Silage and Chemical Composition1,2

533 T E GHNIOAI~ N O T E S Analysis of variance of data in Table 1 resulted in highly significant (P ~ .01) effects of week, sow, week by sow intera...

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533

T E GHNIOAI~ N O T E S

Analysis of variance of data in Table 1 resulted in highly significant (P ~ .01) effects of week, sow, week by sow interaction, and method by week interaction. Effects of method and method by sow interaction were nonsignificant. I n a fixed model, 91.6% of the total variation in Table 1 was associated with sow, week, and sow by week interaction whereas only 8.4% of the variation was associated with method, interactions involving method and error. Colostrum samples were read but were not accurately estimated by the Orange G dye binding method. Colostrum and milk differ in their protein composition; and, consequently, a separate equation would be needed to obtain accurate estimates of protein content of colostrum. Considerably more work is needed to develop equations which will accurately predict protein content of colostrum which is much higher and more variable in protein than normal sow's milk. The orange G method has yielded more repeatable results than the Kjeldahl method (5). As a consequence, any lack of agreement between the two methods is at least as likely to be due to errors in the Kjeldahl method as to be due to errors in the Orange G dye binding procedure. The prediction equation derived for Orange G dye binding procedures provides a rapid and simple method for estimating protein content of sow's milk. Comparison of prediction equations for sow's milk and for cow's milk indicates that use of equations should be limited to the

species involved because of dissimilar protein composition of the milk. l%rthermore, each time a new solution of dye is prepared, it should be compared with a standard milk of that species, and, if necessary, the prediction equation should be adjusted slightly. V. F. COLENBRANDER and 1". G. MARTIN,

Department of Animal Sciences, Purdue University, Lafayette, Indiana 47907 References

(1) Ashworth, U. S., Rupert Seals, and R. E. Erb. 1960. An improved procedure for the determination of milk proteins by dye binding. J. Dairy Sei., 43: 614. (2) Association of Official Analytical Chemists. 1965. Official Methods of Analysis, 10th ed. Washington, D.C. (3) Pond, W. G., L. D. VanVlcck, and D. A. ~Iartman. 1962. Parameters for milk yield and for percents of ash, dry matter, fat and protein in sows. J. Animal Sci., 21: 293. (4) Sheffy, B. E., K. M. Shahani, R. K. Grummer, P. It. Phillips, and It. It. Sommer. 1952. Nitrogen constituents of sow's milk as affected by ration and stage of lactation. J. Nutrition, 48: 103. (5) Tompkins, E. C. 1964. Comparative accuracy of analytical methods for determining protein and solids-not-fat content of milk. M.S. Thesis, Purdue University, Lafayette, Indiana. (6) Udy, D. C. 1956. A rapid method for estimating total protein in milk. Nature, 178: 4528.

Relationships Between Stage of Maturity of the Corn Plant at Time of Harvest for Corn Silage and Chemical Composition Abstract

Two years of data on the effect of date of harvest of the corn plant for ensiling on its chemical composition showed date of harvest had no significant effect on percent crude protein or ether extract. However, in one year date of harvest was correlated with crude fiber (r 2 : 0.60) and nitrogenfree extract (r e = 0.68) and in both years 1 Journal Paper 4228, Purdue University Agricultural Experiment Station, I~afayette, Indiana 47907. 2 The research in this paper was supported in part by a grant-in-aid from the ttarvcstore Division, A. O. Smith Corporation, Arlington Heights, Illinois.

with ash (r 2 = 0.65). I n both years maximum yield of dry matter per hectare occurred at the time the plant contained 33% dry matter. Introduction

Several investigators have studied the effect of stage of matu~ty o£ the corn plant at time of harvest for silage on its yield, acceptability, and digestibility. Perry et al. (7) reported a relatively long period (70 to 84 days) in which maximum yields of digestible dry matter per hectare can be harvested for silage. Bryant et al. (2) found digestibility higher when the grain was in the medium hard dough stage than when it was in the milk stage, JOURNAL OF DAIRY SCIENOE VOL. 54, NO. 4

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The objective of the research herein was to study the effect of stage of maturity of the corn plant at time of harvest for corn silage on its chemical composition. Experimental Procedure

The experiment involved two years of study. The same field in northern Indiana was used and the same fertility practices were followed in each of the two years, although total yield of dry matter was quite different due to a severe drouth in the second year. The corn variety was DeKalb XIA5, seeded at the rate of 59,280 seeds per hectare on May 14, ]965, and May 4, 1966. Nitrogen and potassium were plowed down at the respective rates of 68 and 118 kg and 179 kg per hectare of starter (11-48-0, N, P205 and X ) added at time of planting. Maximum yields of dry matter for the two years were per hectare: total plant, 17,950 and 9,437 kg; ear, 9,828 and 6,011 kg; kernel, 7,007 and 4,743 kg. Harvests were at biweekly intervals early in the harvest period and at 28-day intervals in the latter part. I n the first year of the study the first harvest was August 24, or 101 days after planting, and the last harvest February 22, or 283 days after planting. I n the second year, the first harvest was September 6, or 125 days after planting, and the last harvest May 24, or 385 days after planting. Field conditions prevented more regular harvests the second year. Each harvest was from a measured portion of the field and was weighed for total plant harvest per hectare. Measured portions were hand-picked simultaneously to determine ear and kernel yield per hectare. F r o m each silage harvest , 20 samples (approximately 24 kg dry matter per sample) were stored in double polyethylene bags, 0.004 mm in thickness and measuring 96 by 152 cm. Each sample was treated with carbon dioxide gas, and then each of the two bags for each sample was sealed with a hot iron to maintain semioxygen-free fermentation until each sample was opened for chemical analysis no less than three weeks following harvest. The chemical analyses were made on a composite sample from each of the 20 bags collected for each harvest. Chemieal analyses were eondueted in accordance with procedures outlined by AOAC methods (1). Results and Discuss;on

Two years data on the chemical composition JOURNAL O~ DAIRY SCIE~C~ YOL. 54, NO. 4

of the ensiled whole corn plant as affected by date and stage of maturity are presented. However, because of rainfall conditions, two extremes in plant production are obvious. During the first year (1965-66, Table 1) near optimum rainfall conditions resulted in a maximum dry matter production of ]6,494 kg per hectare as contrasted to 97437 kg p e r hectare in the second year. However, it is of interest that in both years maximum yield of dry matter occurred at the time the whole plant contained 33% dry matter. I n spite of the difference in yield of total dry matter per hectare between the two years, ~here is a striking uniformity of chemical analyses among harvests and even between years. However, changes in crude fiber, ash, and nitrogen-free extract contents were related to d a t e of harvest. During the first year harvest there were decreases in crude fiber (r 2 = 0.60) and ash (r 2 = 0.78) and an increase in nitrogen-free extract @2 _~ 0.68) as the number of days after the initial harvest was begun. I n Year 2 there was a similar decrease in ash content (r 2 ---- 0.65) with increased number of days after the first harvest. Although there were variations among samples (harvest dates) in crude protein content and percent ether extract, no trends were obvious in either of the two years. These data with a relatively unchanging chemical analyses of the silage over a long time may explain the findings of P e r r y et al. (7) who reported a relatively long time (70 to 84 days) in which a maximum of digestible dry matter per hectare could be harvested. Byers and Ormiston (3) reported lowered dry matter digestibility of November-cut silage as compared to that harvested in the dent stage in September (57 versus 63%). These researchers concluded that within the range of the milk to hard seed stages, digestible energy value of corn silage, as fed, is primarily a function of the moisture content. Johnson and ~IcClure (6) conducted a two-year study with sheep to compare the digestibility of the corn plant harvested for silage, starting with the "blister" stage and extending through the "mature" stage. They concluded digestibility of dry matter and organic matter was increased to a maximum at the dough-dent stage and decreased slightly thereafter. Cellulose and erude protein contents decreased (P < .01) in both years with increasing maturity. I n milk production trials Gordon et al. (4) found no difference between normal (28 to 31% dry matter) and late (55 to 63% d~, matter)

TAB•m 1. Effect of st~gc of m a t u r i t y of the corn plant at time of harvest f o r corn silage on its chemical composition. Date of silage harvest

Days after plal~ting

Yield dry matter p e r hectare

Dry matter

Percent maximum yield

Percent grain dry matter

(kg)

(%)

(%)

(%)

1965-66 Aug. 24 Sept: 7 Sept. 21 Oct. 5 Oct. 19 Nov. 2 Nov. 30 Dec. 28 Jan. 26 :Feb. 22

101 115 129 143 157 171 199 227 255 283

11,628 13,100 14,571 16,494 15,533 16,464 14,487 8,807 7,883 7~916

20.1 24.1 28.3 33.3 46.4 52.5 60.9 61.1 74.9 80.3

70.5 79.4 88.4 100.0 94.1 99.1 87.2 53.4 47.5 48.0

...... ...... ...... 42.5 43.0 43.8 47.0 66.7 74.1 76.1

1966-67 Sept. 6 Sept. 20 ¢9 Oct. 4 Oct. 18 ¢ Nov. 1 Nov. 15 i Dec. 27 Feb. 14 May 24

125 139 153 167 181 195 237 286 385

9,437 7,400 7,786 6,728 6,972 6,514 4,872

33.1 32.1 40.8 41.4 51.3 58.0 66.0 71.2 88.6

100.0 78.4 82.5 71.3 73.9 69.0 51.6

47.7 51.9 49.2 52.1 45.1 55.0 62.3 ..........

2~848

30.2

Chemical analyses, dry matter basis Silage pH

Crude protein

Ether extract

Crude a fiber

2ksh b,c

l~-free ° extract

(%)

(%)

(%)

(%)

(%)

4.4 4.5 4.6 4.7 5.0 4.8 5.5 6.5 6.0 6.1

7.8 7.8 7.7 7.7 7.7 7.4 8.2 7.9 8.6 7.5

3.0 .... 3.1 3.5 2.4 2.5 2.8 2.4 3.0 2.8

21.5 24.9 22.3 22.9 22.1 22.3 20.1 21.5 19.2 19.4

3.9 4.1 4.8 4.0 3.4 3.0 3.5 2.5 2.3 2.3

63.8 57.9 62.2 61.9 64.3 64.8 65.4 65.8 66.9 68.0

.... .... .... .... .... .... ....

8.8 9.1 9.4 10.2 9.8 9.7 9.6 9.5 9.5

3.1 3.6 3.6 3.5 3.4 3.7 3.4 3.6 2.7

19.5 18.6 20.2 19.6 20.5 20.1 20.2 19.1 21.0

3.8 4.0 3.3 3.5 3.2 2.7 2.7 2.4 2.6

64.9 64.7 63.5 63.2 63.0 63.9 64.3 66.0 64.5

a Crude fiber for 1965-66, Y = 23.4 -- 0.34X (X ---- No. of 2-week intervals a f t e r first harvest) ; r 2 ---- 0.60. b Ash f o r 1965-66, Y ---- 4.4 -- 0.19X; r s ~ 0.78. c Ash f o r 1966-67, Y ---- 3.62 -- 0.09X; r 2 - - 0.65. d N-free extract for 1965-66, Y ---- 61.0 -- 0.60X; r 2 ~--- 0.68. 9

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harvested corn silage in two successive years. Digestibility trials with sheep showed a small (1.5%) (P < .05) decline in dry matter digestibility of the late silage in the first year's crop but no difference in the second year. No significant differences were found in crude protein, cell wall constituents, cell solubles, or lignin between normal and late harvested silage in either year. I n both years the maximum yield of dry matter per hectare occurred at the time when the whole plant contained 33% dry matter. D. M. CALDWELL and T. W. PERRY, Department of Animal Sciences, Purdue University, Lafayette, Indiana 47907

(3) (4)

(5)

(6)

References

(1) Association of Official Agricultural Chemists. 1965. Official Methods of Analysis. AOAC, Washington, D.C. (2) Bryant, M. T., J. T. :Huber, and R. E. Blaser. 1965. Comparison of corn silage harvested

(7)

SOIENCE

at the milk and medlum-dough stages of maturity for dry matter intake, digestibility, and milk production of lactating cows. J. Dairy Sci., 48. 838. Byers, J. It., and E. E. Ormlston. 1964. Feeding value of mature corn silage. J. Dairy Sci., 47: 707. Gordon, C. H., J. C. Derbyshire, and P. g. Van Soest. 1968. Normal and late harvesting of corn for silage. J. Dairy Sci., 51: 1258. Huber, J. T., G. C. Graf, and R. W. Engle. 1965. Effect of maturity on nutritive value of corn silage for lactating cows. 5. Dairy Sci., 48: 1121. Johnson, R. R., and K. E. McClure. 1968. Corn plant maturity. IV. Effects on digestibility of corn silage in sheep. J. Animal Sci., 27 : 535. Perry, T. W., D. M. Caldwell, J. R. Reedal, and C. B. Knodt. 1968. Stage of maturity of corn at time of harvest for silage and yield of digestible nutrients. J. Dairy Sci., 51 : 799.

Effect of Methane Inhibitors on Rumen Metabolism and Feedlot Performance of Sheep Abstract

I n vitro and in vivo tureen fermentation studies and a lamb performance trial were conducted to discover and evaluate the effect of methane formation-suppressing compounds on tureen metabolism and performance. These experiments indicate that methane inhibitors significantly alter ruminal metabolism resulting in a potentially favorable shift in the proportions of useful metabolites produced in the rumen. The performance data with lambs indicate a trend toward improved feed efficiency with the inhibitor.

Introduction

Gaseous products of rumen fermentation, principally carbon dioxide and methane, can be altered by adding various nutrients or chemicals to the diet (4). Unsaturated Cls fatty acids reduced rumen methanogenesis (5). Methane formation by microorganisms could also be selectively inhibited by adding small amounts of certain other chemicals. F o r example, the methane production in cell-free preparations of Methanobacillus omelianskii was inhibited by low concentrations of certain viologen dyes and by oxygen (18). Chloromethanes added to JOURNAL OF DAIRY SCIENCE VOL. 54, NO. 4

rumen contents inhibited methane fox, nation (2). ttalomethanes reacted with reduced vitamin B12 and inhibited the methyl transfer reaction in methane formation (19). I n normal rumen fermentation, electrons generated during carbohydrate fermentation are used mainly to produce methane, propionic acid (Cs) , and butyric acid (C4) (7). Selective inhibition of methane may lead to an increase in the formation of other reduced products such as molecular hydrogen, ethanol, propionie or butyric or both acids. Chloral hydrate has produced some of these effects in vivo at high or therapeutic levels and also at lower doses (9, 16, 17). I n vitro rumen fermentation studies have shown simple halomethanes (CH2Clz, CHC13, CC14, CH2BrC1) to be potent inhibitors of methane production--less than 10 ppm required for complete inhibition (13). These studies also showed a significant decrease in C2 to C3-4-C4 ratio with no change in total V F A concentration and accumulation of lactic acid and hydrogen. I n vivo experiments with sheep produced similar results (10, 13). Both the extent and duration of methane inhibition were related directly to the amount of compound administered. The following in vitro and in vivo tureen fermentation studies and a feeding trial were