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Complete Rations for Dairy Cattle. I. Methods of Preparation and Roughage-to-Concentrate Ratios of Blended Rations with Corn Silage1
Complete Rations for Dairy Cattle. I. Methods of Preparation and Roughage-to-Concentrate Ratios of Blended Rations with Corn Silage I
S. P. MARSHALL and A. RODRIGUEZ VOIGT: Dairy Science Department University of Ftorida Gainsville 32611 ABSTRACT
Treatment means for dry matter intake, milk production, fat-corrected milk, milk fat test and body weight gains did not differ significantly when rations containing comparable proportions of corn silage and concentrate mixture (30% roughage and 70% concentrate) were fed ad libitum as an ensiled complete ration, a complete ration blended at feeding time, or as separate components in a switchback-type experiment. Ensiling dry matter loss and pH averaged 2.9% and 3.85 for the ensiled complete ration, and 5.0% and 3.75 for the urea-treated silage. Dry matter density of the ensiled complete ration was 81% greater than that of urea-treated silages. In the second experiment, widening roughage-to-concentrate ratios of complete rations from 40:60 to 30:70 to 20:80, was accompanied by stepwise increases in milk production and nonsignificant increases in dry matter intake under ad libitum feeding. Solids-corrected milk production was higher on the 20:80 than on t h e 4 0 : 6 0 roughage-toconcentrate ration. Milk fat tests were lower and body weight gains higher on t h e 20:80 and 30:70 roughage-toconcentrate rations than on the 40:60 ration. Solids-not-fat percentages were similar on all rations. INTRODUCTION
Interest in blended cmplete rations is increasing because they offer a means of controlReceived September 11, 1974. ~Florida Agricultural Experiment Station Journal Series No. 5553. 2Present Address: MAC-FAO, Caracas, Venezuela.
ling the ratio of nutrients consumed, of reducing feeding costs and of diluting ration ingredients. Since silages are a major form of stored roughages fed to dairy cattle and mechanized systems have been developed for feeding them, they offer an attractive base for formulation, and silos are efficient structures for storage of complete rations. Early efforts at making nutritionally improved silages included enrichment of chopped corn with minerals (5) and urea (14) and ensiling only the ear and center part of the stalk (10). Klosterman et al. (6) compared gains by steers fed an ensiled complete ration of chopped corn, corn grain, urea and minerals with a similar ration formulated at feeding. Average daily gains on the ensiled complete ration were significantly higher. Owen and Howard (11) utilized an ensiled complete ration composed of equal parts of dry matter (DM) from chopped alfalfa and cracked corn to study effects of ration moisture upon animal performance and concluded that complete-feed silage had practical potential. Derbyshire et al. (3) ensiled chopped corn alone and with a concentrate mixture added at 15% of fresh weight. When the fortified silage was compared with the control silage plus the same concentrate as 15% of the fresh silage, fat-corrected milk (FCM) production and body weight changes did not differ. Milk production was lower on the ensiled ration. Recently, Hooven et al. (4) and Pardue et al. (12) ensiled in separate silos chopped corn and a complete ration of chopped corn and concentrate mixture to give a 60:40 forage-toconcentrate DM ratio. When the ensiled complete rations fed ad libitum were compared with silage fed ad libitum, with or without a limited amount of hay, and concentrate fed according to production, results were similar. 891
892
MARSHALL AND VOIGT
Experiment I
complete ration was prepared by metering 4.3 kg of urea plus 873.1 kg of moistened concentrate (60% dry matter) onto each metric ton of chopped corn at the conveyor belt of the blower. The concnetrate mixture was motstened to prevent losses as the material was blown into the silo. On the dry matter basis, the concentrate mixture was 59% citrus pulp, 38% cottonseed meal (41% crude protein), 1% urea, 1% defluorinated phosphate, and 1% trace mineral salt. The citrus pulp was ground with a hammer-type mill having a .95 cm screen. The ensiled complete ration contained, on the dry matter basis, 39% concentrate mixture, 31% corn grain from chopped corn, 23% stover, and 7% cob (Table 1).
Nine Holstein and nine Jersey cows past peak of lactation were used in a switchback trial for three treatments (8) to compare an ensiled complete ration, a comparable ration of silage and moistened concentrate mixture blended at feeding, and silage and dry concentrate fed separately but in proportions comparable to that in the complete rations. Following a 14-day standardization, three 28-day treatment periods were used with the last 21 days used for comparison. Urea-treated silage and the ensiled complete ration were prepared on successive days from alternate strips of corn (De Kalb 805) containing 37.8% dry matter which was 51.0% grain, 37.2% stover, and 11.8% cob. These component values were determined by taking stalk samples from six locations, then drying and weighing the parts. Urea (45% N) was added at 4.3 kg per metric ton of chopped corn before ensiling into a vertical-type silo. The
The ratio of concentrate to corn silage in the ratio of each cow was determined at the beginning of the experiment by our feeding 1.8 kg of silage per 100 kg of body weight and supplementing this with the amount of concent-rate needed to meet energy requirements. Silage and concentrate in this ratio then were fed ad libitum. The concentrate part of the rations was reduced 2% weekly, and the concentrate-to-silage ratios were changed accordingly. The highest proportion of concentrate-toroughage offered was that of the ensiled complete ration (70% corn grain plus added concentrate and 30% stover and cob on the DM basis). When a higher proportion of roughage was needed in complete rations, the adjustment was blending appropriate amounts of ureatreated silage into the ensiled ration. The complete rations blended at feeding were prepared by mixing moistened concen-
To evaluate different methods of preparing and feeding rations, comparable proportions of corn silage and concentrate mixture were fed as an ensiled complete ration, a complete ration blended at feeding, and as silage and concentrate mixture fed separately. Fermentation losses, and the density of silage and ensiled complete rations were compared. In a second experiment, three roughage-to-concentrate ratios in complete rations containing silage were compared to try to determine the ratio(s) that give maximum dry matter intake and milk production. E X P E R I M E N T A L PROCEDURE
TABLE 1. Components of ensiled chopped corn and of complete rations, on dry matter basis. Experiment II
Components
Experiment I Ensiled chopped corn
Rations
Stover Cob Corn grain Concentrate
36.7 11.7 50.4 1.2 a
23.0 7.0 31.2 38.8
Rations Roughage-concentrate ratios 40:60 30:70 20:80 (%)
aurea added to chopped corn before ensiling. Journal of Dairy Science Vol. 58, No. 6
29.5 10.7 41.7 18.1
22.0 8.0 31.1 38.9
14.7 5.3 20.7 59.3
COMPLETE RATIONS FOR MILK PRODUCTION trate (60% DM) with the urea-treated silage. Where the silage and dry concentrate were fed separately, the ratio of concentrate to silage DM was maintained under ad libitum feeding by application of the paired feeding technique as described by Mitchell and Beadles (9) to the silage and concentrate allowances. Fermentation dry matter losses were measured by the buried bag technique (1) and drying samples in a vacuum oven (2). Nylon bags containing 1 kg of material were buried at .2, .4, .6, and .8 the height of the silos. Density of the urea-treated chopped corn and of the complete ration after storage in 3 X 9.1 m tower silos was calculated from the weighed inputs of materials and the volume occupied on the 3rd day after ensiling. The cows were kept in individual outside paddocks provided with water, shelter, and feed manger. They were milked twice daily and weights recorded. Aliquots of one day's production were taken weekly for milk fat analysis. All animals were weighed on 3 successive days at the beginning and end of each experimental period. The data were analyzed by analysis of variance, and the Duncan Multiple Range Test was used for comparison of treatment effects. Experiment II
The experimental design and procedure in Experiment I were used to compare complete rations containing, on the dry basis, 40, 30, and 20% of stover and cob from corn silage. Corn (De Kalb 805) containing 34.1% dry matter was chopped with a forage harvester set for a theoretical cut length of .48 cm. On the dry matter basis the chopped corn was 51% grain, 36% stover, and 13% cob. Urea (4.8 kg, 45% N) and 247.2 kg of a moistened concentrate mixture (66% DM) were blended with each metric ton of chopped corn prior to ensiling. The concentrate mixture, on the air dry basis, was 90.6% soybean meal (49% crude protein), .8% urea, 2.2% trace mineral salt, and 6.4% defluorinated phosphate. The ensiled ration contained on the dry basis the following percentages of components: corn grain, 41.7; corn stover, 29.5; corn cob, 10.7; and concentrate mixture, 18.1 (Table 1). The ration with a 30:70 roughage-toconcentrate ratio was prepared by blending 31.5 kg of a moistened (66% DM) concentrate
893
mixture (88% citrus pulp and 12% soybean meal, 49% crude protein) into each 100 kg of ensiled complete ration. That with a 20:80 roughage-to-concentrate ratio was formulated by our blending 62.4 kg of the moistened concentrate with 100 kg of ensiled complete ration. Components of rations and of ensiled chopped corn are in Table 1. Milk fat and specific gravity (2) determinations were made on the milk samples. RESULTS A N D DISCUSSION Experiment I
Treatment means for DM intake, milk production, FCM, milk fat test and body weight gains did not differ significantly (Table 2) indicating satisfactory animal performance on rations of corn silage and concentrate mixture fed ad libitum whether ensiled as a complete ration, blended at feeding time, or offered as separate components in different mangers. These results agree with those reported by other workers (3, 4, 12) who compared ensiled complete rations with similar ration components fed separately. However, Derbyshire et al. (3) observed lower milk production on their ensiled complete ration. All systems studied are feasible nutritionally, thus managerial considerations would influence choice. Ensiling DM losses averaged 2.9% for the ensiled blended ration and 5.0% for the ureatreated silage. Values were similar to the 3.0% reported by Derbyshire et al. (3) for both silage and an ensiled blended ration. The pH was 3.85 for the ensiled complete ration and 3.75 for the urea-treated silage. Density measurements based on weights of material ensiled and space occupied 3 days later were 788 kg of wet material or 352 kg of DM/M 3 for the ensiled complete ration, and 743 kg of forage and urea or 286 kg of DM/M 3 for the urea-treated silage. Incorporating the concentrate mixture into urea-treated chopped corn at ensiling increased DM storage in the silo by 81%. Experiment II
Widening the roughage-to-concentrate ratios from 40:60 to 30:70 to20:80 was accompanied by stepwise increases in average daily milk production (P < .05) and nonsignificant increases in dry matter intake (Table 3). Average Journal of Dairy Science Vol. 58, No. 6
894
MARSHALL AND VOIGT
TABLE 2. Dry matter intake, milk production, milk fat tests, and body weight change in Experiment I.
Treatment
Ensiled complete ration Ration blended at feeding Silage and concentrate fed separately
Dry matter intake
Milk
(% body wt/day) 3.1 3.2 3.1
Fat a
FCMb
Wt gain
(kg/day)
(%)
(kg/day)
(kg/day)
18.7 18.9
4.8 4.8
20.2 20.1
.45 .36
19.3
5.0
20.5
.59
avalues for the 4th wk of treatment period. bFat-corrected milk. daily yield of SCM was higher (P < . 0 5 ) on the 2 0 : 8 0 roughage-to-concentrate ration than on the 4 0 : 6 0 ration. Milk fat tests were lower and average daily gains in b o d y weight greater (P < .05) on the 2 0 : 8 0 and 30:70 roughage-toconcentrate rations than on the 4 0 : 6 0 ration. Solids-not-fat percentages were similar on all rations. The increments in milk p r o d u c t i o n on rations with higher c o n c e n t r a t e were favored by the reductions in milk fat test, increases in dry m a t t e r intake, and a p p a r e n t f r e e d o m f r o m health problems. Milk p r o d u c t i o n increase on the 2 0 : 8 0 ration over that on the 4 0 : 6 0 diet was sufficient to cause an increase in SCM even though the milk fat test was lower on the f o r m e r ration. Since 30:70 roughage-to-concentrate rations generally have s u p p o r t e d normal milk fat tests (13), the short chop of the ensilage (.48 cm theoretical cut length) m a y have influenced the declines in tests on the 30:70 and 2 0 : 8 0 ratio
rations. Silage is effective in maintaining milk fat test as evidenced by only a slightly lower test on a ration fed free choice where the silage furnished 15.1% of dry m a t t e r intake (7). Greater b o d y weight gains on the 30:70 and 2 0 : 8 0 ratio rations probably were due to higher energy intakes on these diets. REFERENCES
1. Alfred, K. R., W. K. Kennedy, L. S. Wittwer, G. W. Trimberger, J. T. Reed, and J. K. Loosli. 1955. Effects of preservatives upon red clover and grass forage ensiled without wilting. Comell Bull. 912. 2. Association of Agricultural Chemists. 1960. Official methods of analysis. 9th ed., Ass. Agr. Chem., Washington, DC. 3. Derbyshire, J. C., C. H. Gordon, and J. L. Humphrey. 1968. The value of fortified corn silage as a complete ration for milking cows. J. Dairy Sci. 51:961. (Abstr.) 4. Hooven, N. W., Jr., R. M. Johnson, and R. D. Plowman. 1971. Complete feed corn silage ration fed at two stages of lactation. J. Dairy Sci. 54:782. (Abstr.) 5. Klosterman, E. W., A. L. Moxon, R. R. Johnson,
TABLE 3. Dry matter intake, milk production, milk composition, and body weight gains in Experiment II. Roughage-toconcentrate ratios
40:60 30:70 20:80
Intake
Milk
SCMa
(% body wt/day)
(kg/day)
(kg/day)
3.2 3.3 3.5
16.9+ 18.5, 19.6,
17.4+ 17.9+ 18.9,
Fat b
SNF c
Wt gain
(%)
(%)
(kg/day)
4.5+ 3.5* 3.4*
9.1 9.1 9.2
.1+ .7+ .8,
asolids-corrected milk. bValnes are for 4th wk of treatment. CSolids-not-fat. +**Values within column with different superscripts differ (P < .05) as determined by Duncan's Multiple Range Test. Journal o f Dairy Science Vol. 58, No. 6
COMPLETE RATIONS FOR MILK PRODUCTION
6.
7.
8. 9.
10.
H. W. Scott, and J. Van Stavern. 1961. Feeding value for fattening cattle of corn silages treated to increase their content o f organic acids. J. Anita. Sci. 20:493. Klosterman, E. W., R. S. Johnson, and K. E. McClure. 1964. Digestibility and feeding value of a complete corn silage. J. Anita. Sci. 23:1223. Larkin, J. C., and O. T. Fosgate. 1970. Comparisons of two different systems of feeding dairy cows for three consecutive lactations. J. Dairy Sci. 53:561. Lucas, H. L. 1956. Switchback trials for more than two treatments. J. Dairy Sci. 39:146. Mitchell, H. H., and J. R. Beadles. 1930. The paired feeding in nutrition experiments and its application to the problem of cystine deficiences in food proteins. J. Nutr. 2:225. Newland, H. W., W. K. Brown, R. J. Deans, C. M.
11.
12.
13. 14.
89 5
Hasen, and J. W. Comstock. 1964. Center-cut silage: A complete energy feed for fattening cattle. Mich. Agr. Exp. Sta. Quart. Bull. 46:374. Owen, F. G., and W. T. Howard. 1965. Effect of ration moisture level on value of alfalfa plus cracked corn as a complete-feed silage for lactating cows. J. Dairy Sci. 48:1310. Pardue, F. F., O. T. Fosgate, G. D. O'Dell, and C. C. Brannon. 1973. Effects of complete ensiled ration on milk production, milk composition, and rumen environment of dairy cattle. J. Dairy Sci. 56:648. Rakes, A. H. 1969. Complete rations for dairy cattle. J. Dairy Sci. 52:870. Wise, G. J., J. H. Mitchell, J. P. La Master, and D. B. Roderick. 1944. Urea-treated corn silage vs. untreated corn silage as a feed for lactating dairy cows. J. Dairy Sci. 27:649.
Journal o f Dairy Science Vol. 58, No. 6
S. P. MARSHALL and A. RODRIGUEZ VOIGT: Dairy Science Department University of Ftorida Gainsville 32611 ABSTRACT
Treatment means for dry matter intake, milk production, fat-corrected milk, milk fat test and body weight gains did not differ significantly when rations containing comparable proportions of corn silage and concentrate mixture (30% roughage and 70% concentrate) were fed ad libitum as an ensiled complete ration, a complete ration blended at feeding time, or as separate components in a switchback-type experiment. Ensiling dry matter loss and pH averaged 2.9% and 3.85 for the ensiled complete ration, and 5.0% and 3.75 for the urea-treated silage. Dry matter density of the ensiled complete ration was 81% greater than that of urea-treated silages. In the second experiment, widening roughage-to-concentrate ratios of complete rations from 40:60 to 30:70 to 20:80, was accompanied by stepwise increases in milk production and nonsignificant increases in dry matter intake under ad libitum feeding. Solids-corrected milk production was higher on the 20:80 than on t h e 4 0 : 6 0 roughage-toconcentrate ration. Milk fat tests were lower and body weight gains higher on t h e 20:80 and 30:70 roughage-toconcentrate rations than on the 40:60 ration. Solids-not-fat percentages were similar on all rations. INTRODUCTION
Interest in blended cmplete rations is increasing because they offer a means of controlReceived September 11, 1974. ~Florida Agricultural Experiment Station Journal Series No. 5553. 2Present Address: MAC-FAO, Caracas, Venezuela.
ling the ratio of nutrients consumed, of reducing feeding costs and of diluting ration ingredients. Since silages are a major form of stored roughages fed to dairy cattle and mechanized systems have been developed for feeding them, they offer an attractive base for formulation, and silos are efficient structures for storage of complete rations. Early efforts at making nutritionally improved silages included enrichment of chopped corn with minerals (5) and urea (14) and ensiling only the ear and center part of the stalk (10). Klosterman et al. (6) compared gains by steers fed an ensiled complete ration of chopped corn, corn grain, urea and minerals with a similar ration formulated at feeding. Average daily gains on the ensiled complete ration were significantly higher. Owen and Howard (11) utilized an ensiled complete ration composed of equal parts of dry matter (DM) from chopped alfalfa and cracked corn to study effects of ration moisture upon animal performance and concluded that complete-feed silage had practical potential. Derbyshire et al. (3) ensiled chopped corn alone and with a concentrate mixture added at 15% of fresh weight. When the fortified silage was compared with the control silage plus the same concentrate as 15% of the fresh silage, fat-corrected milk (FCM) production and body weight changes did not differ. Milk production was lower on the ensiled ration. Recently, Hooven et al. (4) and Pardue et al. (12) ensiled in separate silos chopped corn and a complete ration of chopped corn and concentrate mixture to give a 60:40 forage-toconcentrate DM ratio. When the ensiled complete rations fed ad libitum were compared with silage fed ad libitum, with or without a limited amount of hay, and concentrate fed according to production, results were similar. 891
892
MARSHALL AND VOIGT
Experiment I
complete ration was prepared by metering 4.3 kg of urea plus 873.1 kg of moistened concentrate (60% dry matter) onto each metric ton of chopped corn at the conveyor belt of the blower. The concnetrate mixture was motstened to prevent losses as the material was blown into the silo. On the dry matter basis, the concentrate mixture was 59% citrus pulp, 38% cottonseed meal (41% crude protein), 1% urea, 1% defluorinated phosphate, and 1% trace mineral salt. The citrus pulp was ground with a hammer-type mill having a .95 cm screen. The ensiled complete ration contained, on the dry matter basis, 39% concentrate mixture, 31% corn grain from chopped corn, 23% stover, and 7% cob (Table 1).
Nine Holstein and nine Jersey cows past peak of lactation were used in a switchback trial for three treatments (8) to compare an ensiled complete ration, a comparable ration of silage and moistened concentrate mixture blended at feeding, and silage and dry concentrate fed separately but in proportions comparable to that in the complete rations. Following a 14-day standardization, three 28-day treatment periods were used with the last 21 days used for comparison. Urea-treated silage and the ensiled complete ration were prepared on successive days from alternate strips of corn (De Kalb 805) containing 37.8% dry matter which was 51.0% grain, 37.2% stover, and 11.8% cob. These component values were determined by taking stalk samples from six locations, then drying and weighing the parts. Urea (45% N) was added at 4.3 kg per metric ton of chopped corn before ensiling into a vertical-type silo. The
The ratio of concentrate to corn silage in the ratio of each cow was determined at the beginning of the experiment by our feeding 1.8 kg of silage per 100 kg of body weight and supplementing this with the amount of concent-rate needed to meet energy requirements. Silage and concentrate in this ratio then were fed ad libitum. The concentrate part of the rations was reduced 2% weekly, and the concentrate-to-silage ratios were changed accordingly. The highest proportion of concentrate-toroughage offered was that of the ensiled complete ration (70% corn grain plus added concentrate and 30% stover and cob on the DM basis). When a higher proportion of roughage was needed in complete rations, the adjustment was blending appropriate amounts of ureatreated silage into the ensiled ration. The complete rations blended at feeding were prepared by mixing moistened concen-
To evaluate different methods of preparing and feeding rations, comparable proportions of corn silage and concentrate mixture were fed as an ensiled complete ration, a complete ration blended at feeding, and as silage and concentrate mixture fed separately. Fermentation losses, and the density of silage and ensiled complete rations were compared. In a second experiment, three roughage-to-concentrate ratios in complete rations containing silage were compared to try to determine the ratio(s) that give maximum dry matter intake and milk production. E X P E R I M E N T A L PROCEDURE
TABLE 1. Components of ensiled chopped corn and of complete rations, on dry matter basis. Experiment II
Components
Experiment I Ensiled chopped corn
Rations
Stover Cob Corn grain Concentrate
36.7 11.7 50.4 1.2 a
23.0 7.0 31.2 38.8
Rations Roughage-concentrate ratios 40:60 30:70 20:80 (%)
aurea added to chopped corn before ensiling. Journal of Dairy Science Vol. 58, No. 6
29.5 10.7 41.7 18.1
22.0 8.0 31.1 38.9
14.7 5.3 20.7 59.3
COMPLETE RATIONS FOR MILK PRODUCTION trate (60% DM) with the urea-treated silage. Where the silage and dry concentrate were fed separately, the ratio of concentrate to silage DM was maintained under ad libitum feeding by application of the paired feeding technique as described by Mitchell and Beadles (9) to the silage and concentrate allowances. Fermentation dry matter losses were measured by the buried bag technique (1) and drying samples in a vacuum oven (2). Nylon bags containing 1 kg of material were buried at .2, .4, .6, and .8 the height of the silos. Density of the urea-treated chopped corn and of the complete ration after storage in 3 X 9.1 m tower silos was calculated from the weighed inputs of materials and the volume occupied on the 3rd day after ensiling. The cows were kept in individual outside paddocks provided with water, shelter, and feed manger. They were milked twice daily and weights recorded. Aliquots of one day's production were taken weekly for milk fat analysis. All animals were weighed on 3 successive days at the beginning and end of each experimental period. The data were analyzed by analysis of variance, and the Duncan Multiple Range Test was used for comparison of treatment effects. Experiment II
The experimental design and procedure in Experiment I were used to compare complete rations containing, on the dry basis, 40, 30, and 20% of stover and cob from corn silage. Corn (De Kalb 805) containing 34.1% dry matter was chopped with a forage harvester set for a theoretical cut length of .48 cm. On the dry matter basis the chopped corn was 51% grain, 36% stover, and 13% cob. Urea (4.8 kg, 45% N) and 247.2 kg of a moistened concentrate mixture (66% DM) were blended with each metric ton of chopped corn prior to ensiling. The concentrate mixture, on the air dry basis, was 90.6% soybean meal (49% crude protein), .8% urea, 2.2% trace mineral salt, and 6.4% defluorinated phosphate. The ensiled ration contained on the dry basis the following percentages of components: corn grain, 41.7; corn stover, 29.5; corn cob, 10.7; and concentrate mixture, 18.1 (Table 1). The ration with a 30:70 roughage-toconcentrate ratio was prepared by blending 31.5 kg of a moistened (66% DM) concentrate
893
mixture (88% citrus pulp and 12% soybean meal, 49% crude protein) into each 100 kg of ensiled complete ration. That with a 20:80 roughage-to-concentrate ratio was formulated by our blending 62.4 kg of the moistened concentrate with 100 kg of ensiled complete ration. Components of rations and of ensiled chopped corn are in Table 1. Milk fat and specific gravity (2) determinations were made on the milk samples. RESULTS A N D DISCUSSION Experiment I
Treatment means for DM intake, milk production, FCM, milk fat test and body weight gains did not differ significantly (Table 2) indicating satisfactory animal performance on rations of corn silage and concentrate mixture fed ad libitum whether ensiled as a complete ration, blended at feeding time, or offered as separate components in different mangers. These results agree with those reported by other workers (3, 4, 12) who compared ensiled complete rations with similar ration components fed separately. However, Derbyshire et al. (3) observed lower milk production on their ensiled complete ration. All systems studied are feasible nutritionally, thus managerial considerations would influence choice. Ensiling DM losses averaged 2.9% for the ensiled blended ration and 5.0% for the ureatreated silage. Values were similar to the 3.0% reported by Derbyshire et al. (3) for both silage and an ensiled blended ration. The pH was 3.85 for the ensiled complete ration and 3.75 for the urea-treated silage. Density measurements based on weights of material ensiled and space occupied 3 days later were 788 kg of wet material or 352 kg of DM/M 3 for the ensiled complete ration, and 743 kg of forage and urea or 286 kg of DM/M 3 for the urea-treated silage. Incorporating the concentrate mixture into urea-treated chopped corn at ensiling increased DM storage in the silo by 81%. Experiment II
Widening the roughage-to-concentrate ratios from 40:60 to 30:70 to20:80 was accompanied by stepwise increases in average daily milk production (P < .05) and nonsignificant increases in dry matter intake (Table 3). Average Journal of Dairy Science Vol. 58, No. 6
894
MARSHALL AND VOIGT
TABLE 2. Dry matter intake, milk production, milk fat tests, and body weight change in Experiment I.
Treatment
Ensiled complete ration Ration blended at feeding Silage and concentrate fed separately
Dry matter intake
Milk
(% body wt/day) 3.1 3.2 3.1
Fat a
FCMb
Wt gain
(kg/day)
(%)
(kg/day)
(kg/day)
18.7 18.9
4.8 4.8
20.2 20.1
.45 .36
19.3
5.0
20.5
.59
avalues for the 4th wk of treatment period. bFat-corrected milk. daily yield of SCM was higher (P < . 0 5 ) on the 2 0 : 8 0 roughage-to-concentrate ration than on the 4 0 : 6 0 ration. Milk fat tests were lower and average daily gains in b o d y weight greater (P < .05) on the 2 0 : 8 0 and 30:70 roughage-toconcentrate rations than on the 4 0 : 6 0 ration. Solids-not-fat percentages were similar on all rations. The increments in milk p r o d u c t i o n on rations with higher c o n c e n t r a t e were favored by the reductions in milk fat test, increases in dry m a t t e r intake, and a p p a r e n t f r e e d o m f r o m health problems. Milk p r o d u c t i o n increase on the 2 0 : 8 0 ration over that on the 4 0 : 6 0 diet was sufficient to cause an increase in SCM even though the milk fat test was lower on the f o r m e r ration. Since 30:70 roughage-to-concentrate rations generally have s u p p o r t e d normal milk fat tests (13), the short chop of the ensilage (.48 cm theoretical cut length) m a y have influenced the declines in tests on the 30:70 and 2 0 : 8 0 ratio
rations. Silage is effective in maintaining milk fat test as evidenced by only a slightly lower test on a ration fed free choice where the silage furnished 15.1% of dry m a t t e r intake (7). Greater b o d y weight gains on the 30:70 and 2 0 : 8 0 ratio rations probably were due to higher energy intakes on these diets. REFERENCES
1. Alfred, K. R., W. K. Kennedy, L. S. Wittwer, G. W. Trimberger, J. T. Reed, and J. K. Loosli. 1955. Effects of preservatives upon red clover and grass forage ensiled without wilting. Comell Bull. 912. 2. Association of Agricultural Chemists. 1960. Official methods of analysis. 9th ed., Ass. Agr. Chem., Washington, DC. 3. Derbyshire, J. C., C. H. Gordon, and J. L. Humphrey. 1968. The value of fortified corn silage as a complete ration for milking cows. J. Dairy Sci. 51:961. (Abstr.) 4. Hooven, N. W., Jr., R. M. Johnson, and R. D. Plowman. 1971. Complete feed corn silage ration fed at two stages of lactation. J. Dairy Sci. 54:782. (Abstr.) 5. Klosterman, E. W., A. L. Moxon, R. R. Johnson,
TABLE 3. Dry matter intake, milk production, milk composition, and body weight gains in Experiment II. Roughage-toconcentrate ratios
40:60 30:70 20:80
Intake
Milk
SCMa
(% body wt/day)
(kg/day)
(kg/day)
3.2 3.3 3.5
16.9+ 18.5, 19.6,
17.4+ 17.9+ 18.9,
Fat b
SNF c
Wt gain
(%)
(%)
(kg/day)
4.5+ 3.5* 3.4*
9.1 9.1 9.2
.1+ .7+ .8,
asolids-corrected milk. bValnes are for 4th wk of treatment. CSolids-not-fat. +**Values within column with different superscripts differ (P < .05) as determined by Duncan's Multiple Range Test. Journal o f Dairy Science Vol. 58, No. 6
COMPLETE RATIONS FOR MILK PRODUCTION
6.
7.
8. 9.
10.
H. W. Scott, and J. Van Stavern. 1961. Feeding value for fattening cattle of corn silages treated to increase their content o f organic acids. J. Anita. Sci. 20:493. Klosterman, E. W., R. S. Johnson, and K. E. McClure. 1964. Digestibility and feeding value of a complete corn silage. J. Anita. Sci. 23:1223. Larkin, J. C., and O. T. Fosgate. 1970. Comparisons of two different systems of feeding dairy cows for three consecutive lactations. J. Dairy Sci. 53:561. Lucas, H. L. 1956. Switchback trials for more than two treatments. J. Dairy Sci. 39:146. Mitchell, H. H., and J. R. Beadles. 1930. The paired feeding in nutrition experiments and its application to the problem of cystine deficiences in food proteins. J. Nutr. 2:225. Newland, H. W., W. K. Brown, R. J. Deans, C. M.
11.
12.
13. 14.
89 5
Hasen, and J. W. Comstock. 1964. Center-cut silage: A complete energy feed for fattening cattle. Mich. Agr. Exp. Sta. Quart. Bull. 46:374. Owen, F. G., and W. T. Howard. 1965. Effect of ration moisture level on value of alfalfa plus cracked corn as a complete-feed silage for lactating cows. J. Dairy Sci. 48:1310. Pardue, F. F., O. T. Fosgate, G. D. O'Dell, and C. C. Brannon. 1973. Effects of complete ensiled ration on milk production, milk composition, and rumen environment of dairy cattle. J. Dairy Sci. 56:648. Rakes, A. H. 1969. Complete rations for dairy cattle. J. Dairy Sci. 52:870. Wise, G. J., J. H. Mitchell, J. P. La Master, and D. B. Roderick. 1944. Urea-treated corn silage vs. untreated corn silage as a feed for lactating dairy cows. J. Dairy Sci. 27:649.
Journal o f Dairy Science Vol. 58, No. 6