Intake and Value for Milk Production of Oat Silages Ensiled at Three Stages of Maturity and Preserved with Sodium Metabisulfite1, 2

INTAKE

AND VALUE FOR MILK PRODUCTION OF OAT SILAGES ENSILED AT THREE STAGES OF 5~ATURITY AND PRESERVED WITH SODIUM METABISULFITE 1,

F. A. MARTZ, C. g . NOLLER, D. L. HILL, ANt>.~. W. C.A~TER :~ Dairy Department, Indiana Agricultural Experiment Station, Lafayette SUMMARY

The intake and value for nfilk production of oats castled at three stages of nmturity: boot, early-milk, and soft-dough, were compared with each other and with an alfalfagrass mixed silage. Twelve milking cows were used in an extra-period 4 × 4 Latin square changeover design. I n this experiment, the oat silagcs supplied 86.6-88.0% and the alfalfa-grass silage 86.1% of the total forage d r y matter intake. D r y matter intake of the soft-dough stage oats was the highest, but the TDN intake was higher with the bootstage oats. Differences between oat silages for milk production were correlated with differences in TDN intake from the silages. Acceptable silages were made at all three stages of maturity. I t was concluded that the optimum stage to ensile oats is at the boot stage or soon thereafter. Sodium metabisulfite was a satisfactory preservative. The f u n d a m e n t a l o b j e c t i v e u n d e r l y i n g a l l a t t e m p t s to conserve oats as a f o r a g e c r o p is to effectively p r e s e r v e the n u t r i e n t s in a p a l a t a b l e c o n d i t i o n . H o w e v e r , oat silage f e e d i n g to d a i r y c a t t l e g e n e r a l l y h a s been d i s a p p o i n t i n g . C h e m i c a l a n a l y s e s h a v e i n d i c a t e d m a r k e d c h a n g e s in c o m p o s i t i o n of oat f o r a g e w i t h a d v a n c e in m a t u r i t y w h e n h a r v e s t e d as h a y (9) or silage (11). The o p t i m u m s t a g e to h a r v e s t t h e oat p l a n t as a feed, a n d t h e p r o p e r m e t h o d s f o r c a s t l i n g to e n s u r e a q u a l i t y pro'duet, h a v e n o t been established. I t h a s been shown t h a t a d d i t i v e s or p r e s e r v a t i v e s a r e beneficial w h e n e n s i l i n g c e r t a i n g r e e n c r o p s (12). H i l l et al. (3) f o u n d t h a t t h e boot s t a g e was t h e most f a v o r a b l e s t a g e f o r o b t a i n i n g a d e s i r a b l e silage f e r m e n t a t i o n w i t h o u t t h e use of a n a d d i t i v e . F o r m i l k a n d d o u g h stages, a n a d d i t i v e was d e s i r a b l e . M e C u l l o u g h ct al. (8) o b t a i n e d optimum preservation and feeding value at the prebloom stage and concluded t h a t g r o u n d s n a p c o r n was a beneficial p r e s e r v a t i v e b u t t h a t s o d i u m m e t a b i sulfite was u n s a t i s f a c t o r y . T h u r m a n et aI. (11) c o n c l u d e d t h a t oats s h o u l d be ensiled b e t w e e n t h e boot a n d m i l k stage. The p u r p o s e of t h i s i n v e s t i g a t i o n was to c o m p a r e t h e i n t a k e a n d v a l u e f o r m i l k p r o d u c t i o n of oats ensiled a t t h r e e stage~ of m a t u r i t y a n d p r e s e r v e d w i t h s o d i u m metabisulfite. EXPERIMENTAL PROCEDURE C l i n t l a n d oats were h a r v e s t e d f o r silage a t t h r e e stages of m a t u r i t y : (1) boot, j u s t p r i o r to c o m p l e t e e m e r g e n c e of t h e inflorescence f r o m t h e sheath, ( I I ) e a r l y Received for publication July 20, 1959. Published with the approval of the Director of the Indiana Agricultural Experiment Station as Journal Series Paper No. 1455. The data are from a thesis submitted by the senior author to tile Graduate School in partial fulfillment o2 the requirements for the Master of Science degree. * Present address: Department of Experimental Statlsties, ~Torth Carolina State College, Raleigh. 1955

1956

F

A. MXRTZ

ET

AL

milk, and ( I I I ) soft-dough. An alfalfa-Ladino-bromegrass mixture ( i V ) was ensiled as a control silage when the alfalfa was in the 1/10 bloom stage. All forages were direct-cut, treated with 6-8 lb. of sodium metabisulfite per ton, and ensiled in u p r i g h t steel silos. Sodium metabisulfite has been shown to be an effective preservative (2), and was used because it contrilmted no food value. Intake and milk production were studied, using 12 lactating cows in the period between peak-lactation and mid-gestation. The co~s were divided into three groups of four cows each, so that animals within a group were producing at comparable levels. A balanced extra-period 4 × 4 Latin-square changeover design with three squares was used (7). The three groups were allotted to three squares and the animals were r a n d o m l y assigned to the treatment sequences. The t r e a t m e n t periods were 15 days in length, composed of a seven-day a d j u s t m e n t period followed by an eight-day experimental period. The final analyses were made on the data f r o m the eight-day experimental period. I m m e d i a t e l y prior to the experiment, the animals were allowed 2 wk. to adjust to the experimental feeds and routine. The silages were fed in ad libitum amounts five or six times daily. A grain mixture containing 18.8% crude protein was fed at the rate of 1 lb. of grain for each 6 lb. of fat-corrected milk ( F C M ) produced. The composition was as follows, in pounds: ground corn, 400: ground oats, 200; soybean oil meal, 200; steamed bone meal, 8; and iodized salt, 8. Changes in amount of grain fed were made at the beginning of each treatment period, based on production during the preceding experimental period. Goodquality alfalfa hay was fed at 0.3 lb. daily per 100 lb. body weight, based on weights obtained three consecutive days prior to the first treatment period. D u r i n g the experiment, the cows were weighed at the same time of day on the last three days of the seven-day adjustment period and the last three days of the eight-day experimental period. Silage samples were taken weekly for determination of moisture, titratable acidity, and p H . The per cent moisture was determined by the toluene distillation method. The samples were stored in a deep freeze; later, they were cornposited and oven-dried. Chemical analyses of the silages, hay, and grain were made, using accepted A.O.A.C. procedures (1). The proximate analyses of the grain, hay, and silages are shown in Table 1. The data were analyzed according to the statistical procedures outlined by Lucas (7). Individual differences among silages in d r y matter intake and F C M TABLE 1 P r o x i m a t e analyses of grain, hay, and silages Feed Silage I Silage I I Silage I I I Silage I V Grain mix Hay

Dry matter

Crude protein

Crude fiber

Ether extract

Ash

N.F.E.

21.0 23.5 29.9 25.5 90.7 90.7

2.33 2.56 2.87 3.08 18.78 14.79

6.74 7.21 8.97 9.25 5.80 33.36

1.13 0.92 1.06 1.07 3.17 2.17

2.08 2.46 2.96 2.06 4.90 5.9O

8.75 10.34 14.04 10.02 58.04 33.80

pH

Titratable acidity

4.40 0.79 4.65 0.57 4.60 0.84 4.39 1.11 ............ ............

1957

OAT SILAGES FOR MILK PRODUCTION

produced were tested for significance with the Neuman-Keuls Sequential Range Test (4). Total digestible n u t r i e n t (TDN) values were obtained for the oat silages, using nine 8-mo.-old Holstein bulls which had been on high roughage programs. Three animals were assigned at random to each of the oat silages. The procedure for a conventional digestion trial was followed, with the exception that plastic bags were used for collecting the feces (10). A 21-day preliminary period was followed by a seven-day fecal collection period. RESULTS AND DISCUSSION

The oat silages used in the experiment were readily consumed and supplied 86.6-88.0~, and alfalfa grass silage 86.1%, of the d r y m a t t e r intake from forage. The average daily feed intakes are presented in Table 2. Analyses of variance of silage d r y matter intakes (Table 3) show a significant difference between silages. The d r y matter intake of Silage I I I was significantly higher than that of Silages I, II, and IV. The differences in intake among Silages I, II, aud IV were small and not significant. Even though the cows consumed 3.5 lb. more d r y matter daily when fed Silage I I I as compared to Silage I, the daily TDN intake was 0.98 lb. greater from Silage J, because the TDN value of the dry matter (10) was 67.1 and 54.1 for Silages f and III, respeetively. The TDN intake from the silages ranged between 69.6-74.9% of the total. TABLE 2 A v e r a g e daily feed intake, milk p r o d u c t i o n , a n d body w e i g h t s Silage Feed c o n s u m p t i o n Silage dry m a t t e r (lb.) T D N f r o m silage (lb.) Grail1 (lb.) H a y (lb.) F C M p r o d u c e d (lb.) Lb. T D N / l b F C M Body w e i g h t (lb.) W e i g h t c h a n g e (lb.)

I Boot

II Early-Milk

21.90 14.68 4.13 3.57 23.30 b .84 1,190 +.42

III Soft-Dough

21.00 12.79 3.86 3.59 21.10 .83 1,186 +.24

IV A l f a l f a -grass

25.40 ~ 13.70 4.00 3.84 22.20 .84 1,189 --1.21

19.90 11.12 4.06 3.55 21.70 .74 1,182 --.85

Significantly different f r o m Silage I ( P ~ 0.05) a n d f r o m Silages I I a n d I V ( P ~ 0.01). " Significantly different f r o m Silage I I ( P ~ 0.05). TABLE 3 A n a l y s i s of v a r i a n c e of d a t a on a v e r a g e daily silage dry m a t t e r i n t a k e s Source Total Square

('ow in s q u a r e s Periods Periods × squares Direct effect Direct effect × s q u a r e Residual Residual × square Error

D e g r e e s of f r e e d o m

Mean square

F value

59 2 9 4 8 3 6 3 6 17

442.20 13.12 2.31 3.77 80.00 9.86 11.19 3.9~ 4.53

61.10" 2.91 ~ 1 ~ 1 17.66 ~ 2.17 2.47 ~ 1

a Significant at t h e 0.01 level of probability.

1958

F.A.

MARTZ ET AL

There is evidence that the type of fermentation will affect the acceptability of the resulting silages. Therefore, d r y matter intakes are influenced by fermentation characteristics as well as by the nutritive value of the forage. Laboratory evaluation indicated that the silages had undergone satisfaeto'ry fermentations. None of them had offensive odors. They were not slick or slimy to the touch. The color was good, indicating that they had not developed excessively high temperatures. The p H and titratable acid values (Table 1) were representative of silages treated with sodium metabisulfite. The bo'ot-stage silage developed a lower p H than the soft-dough or early-milk stage silages. These results are in agreement with previous findings that oats harvested during the boot stage developed lower p H values (3). I n disagreement with the suggestion that sodium metabisulfite is not a satisfactory preservative for oat silage (8), animal acceptance of the oat silages indicated that sodium metabisulfite was an effective preservative for making oat silages at these stages of maturity. The treatment means for daily F C M are presented in Table 2. The cows on Silage I produced more F C M than those on the other silages. The only significant difference was between Silages I and I I (P ~ 0.05). The F C M for the other two silages was intermediate. The differences between oat silages in milk yield were correlated with differences in TDN intake. The similarity in TDN from the three o'at silages is illustrated by TDN consumption per pound of FCM produced (Table 2). The more efficient conversion of TDN from the grasslegume silage may be a reflection of a more favorable nutrient content or combination. Thus, intake, subjective evaluation, and chemical composition are only p a r t l y reliable measures fo'r comparing the milk-producing potential of oat silage and other types of silage. The low value of TDN front oat silages for milk production has also been observed by other workers (5, 6). The extra-period Latin square changeover design permitted the measurement of carryover effect (7). The analyses of variance of silage d r y matter intakes (Table 3) and FCM (Table 4) showed that, if present, any carryover effects were essentially completed within the first seven days on a new treatment. Although this design would have permitted the adjustment of the means to eliminate carryover, this was not necessary. The length of time required to T ABLE 4 Analysis of variance of data on average daily fat-corrected milk produced Source Total Square Cow in squares Periods Periods × square Direct effect Direct effect X square Residual Residual × square Error

Degrees of freedom

Mean square

F value

59 2 9 4 8 3 6 3 6 17

1,070.90 125.72 95.22 2.72 12.25 2.79 4.07 2.00 3.75

285.04~' 33.46 25.34 1 3.27~ 1 1.08 1

Significant at the 0.05 level of probability. ~'Significant ~t the 0.01 ]evel of probability.

OAT SILA@ES FO~ IMILK PRODUCTION

1959

e l i m i n a t e t h e c a r r y o v e r effect in a p a r t i c u l a r e x p e r i m e n t would, no doubt, be m a r k e d l y i n f l u e n c e d b y th e f a c t o r s b e i n g studied. A l t h o u g h the cows w e r e w e i g h e d at r e g u l a r i n t e r v a l s , the significance of t h e v a l u e s o b t a i n e d ( T a b l e 2) is s u b j e c t to' d o u b t because of t h e s h o r t e x p e r i m e n t a l periods. Also, the v a l u e s o b t a i n e d do n o t d i f f e r e n t i a t e b e t w e e n t r u e a n d p s e u d o b o d y w e i g h t changes. T h e d a t a s u g g e s t t h a t a c c e p t a b l e oat silages can be m a d e at all of the stages of m a t u r i t y studied, a n d t h a t s o d i u m m e t a b i s u l f i t e is a s a t i s f a c t o r y p r e s e r v a t i v e f o r m a k i n g silages w i t h e x c e l l e n t f e r m e n t a t i o n c h a r a c t e r i s t i c s . Also, t h e y i n d i cate f r o m the s t a n d p o i n t of f e r m e n t a t i o n a n d m i l k p r o d u c t i o n t h a t oats should be h a r v e s t e d f o r silage at a p p r o x i m a t e l y t he boot stage, or soon t h e r e a f t e r . Si n ce oats o f t e n are used as a n u r s e crop f o r n e w seedling's of l e g u m e s a n d grasses, the e a r l i e r r e m o v a l of the oats w o u l d c o n s e r v e soil m o i s t u r e a n d give the l e g m n e or grass s e e d i n g a b e t t e r o p p o r t u n i t y f o r g r o w t h . I t w o u l d a p p e a r t h a t t h e differences b e t w e e n these oat silages a r e d u e e s s e n t i a l l y to t h e a m o u n t of T D N supplied. T h e T D N in silage m a d e f r o m C l i n t l a n d oats was n o t used as efficiently f o r m i l k p r o d u c t i o n as the T D N f r o m th e l e g m n e - g r a s s silage. REFERENCES (1) ASSOCIATIONOF OF'I~ICIALAGRICULTURALCHE~IS'rs. ONcial Methods of Analysis. 8th ed. Washington, D. C. 1955. (2) :BltATZL~,J. W., COWAN.R. L., A~]) SWIFT, R. W. Grass Silage Preservation with Sodium Metabisulphite. J. A~timal Sci., 15: 163. 1955. (3) HmL, D. L., NOLL~a, C. H., MA~WZ, F. A., aNa L.~TNI)QUIST,N. S. Preservation of Oats as Silage. Purdue Agr. Expt. Sta., Mimeo DH-73. 1958. (4) KE:ULS, M. The Use of "Stuclentized Range" in Connection with an Analysis of Variance. Ew~hytica, 1: 112. 1952. (5) KING, W. A. Comparison of Molasses-Oat Silage and Phosphoric Acid-Oat Silage as Feed for the Milking" Cow. New Jersey Agr. Expt. Sta., Bull. 708. 1944. (6) LASSITE'R,C. A., HIIFP~fAN, C. P., DgXT'E'R.,S. T., AND DUNC'AN,C. W. Corn versus Oat Silage as a Roughage for Dairy Cattle. J. Dairy Sci., 41: 1282. 1958. (7) LUCAS, H. L. Extra-Period Latin-Square Changeover Designs. J. Dairy Sei., 40: 225. 1957. (8) MCCULLOUGI~I,M. E., DIS~:, L. R., AND SELL, O. E. Influence of Stage of Maturity and of Ground Snap Corn or Sodium Metabisulfite as Preservatives on the Feeding Value of Oat Silages. Y. Dairy Sci., 41: 796. 1958. (9) MI~YEIR,J. H., WE.IR.~ W. C., JONE4S, L. G., AND HALL, J. L. The Influence of Stage of Maturity on the Feeding Value of Oat Hay. J. Animal Sci., 16: 623. 1957. (10) ~OL.LIgI%,C.. H., STILLONS, M. C., MAIaTZ, F. A. AND HILL, D. L. Digestion Studies with Oat Silages Using a New Fecal Collection Technique. J. Animal Sci., 18: 671. 1959. (11) TttURI~IAN,R. L., STALLCUP,O. T., ST]~PttENS, J. L., AND JUSTVS, N. E. When to Harvest Oats for Hay and Silage. Arkansas Agr. Expt. Sta., B~dl. 586. 1957. (12) WALKER, B. J. Laboratory Studies on Silage Fermentation. Ph.D. thesis, Purdue University. 1959.