Effect of Microbial Inoculant on Quality of Alfalfa Hay Baled at High Moisture and Lamb Performance1,2 S. M. EMANUELE, G.M.J. HORTON, and J. BALDWIN Department of Animal Sciences Rutgers University New Brunswick, NJ 08903-0231

D. LEE Rutgers Cooperative Extension Salem County Woodstown, NJ W. H. MAHANA Pioneer Hi-Bred International Microbial Genetics Division Des Moines, IA 50365 ABSTRACT

hay plus corn; and chopped, high moisture hay plus corn. All diets contained 63% alfalfa hay, 35% ground corn, and 2% minerals and vitamins. In yr 1, inoculated and low moisture hays were not different in chemical composition but were higher in CP and lower in NDF than high moisture hay. Neither NDF nor CP were different among the three hays in yr 2. Average daily gain was not different on the three diets. The feed to gain ratio was lowest for the inoculated hay, intermediate for the low moisture hay, and highest for the high moisture hay diet. Daily gain and feed to gain ratio were not different for lambs fed the inoculated hay baled at 75% OM compared with lambs fed untreated hay baled at 82% OM. (Key words: bacterial inoculant, hay preservation, forage quality)

. The effectiveness of a microbial hay Inoculant in high moisture alfalfa hay was evaluated. Alfalfa (third cutting) was baled at 72% OM without or with inoculant and at 82% OM without inoculant during yr 1. In yr 2, alfalfa (second cutting) was baled at 75% OM without or with inoculant and at 82% OM without inoculant. Application rate of inoculant was 3.8 U.98 tonne each year. At this application rate, 90 billion cfu were applied per .98 tonne of forage. Hays were core sampled at 0, 14,30, and 60 d after baling to determine chemical composition. By d 30, all hays had OM content of 89%. In yr 2, 12 wether lambs were assigned to three treatments in a replicated 3 x 3 Latin square. Treatments were chopped, low moisture hay plus corn; chopped, inoculated high moisture

Abbreviation key: 8M

= low

Received September 3. 1991. Accepted June 3. 1992. l~ention of a proprietary product or vendor does not con~tute a w~ty of the product by the New Jersey A~cultural Expenment Station. Rutgers Cooperative ExtensIOn, or Rutgers University and does not imply its approval to the exclusion of other suitable products. 2Study funded by a grant from the Microbial Genetics Division of Pioneer HiBred International Des Moines IA 50365. • •

1992 J Dairy Sci 75:3084-3090

= high moisture, LM

moisture. INTRODUCTION

Many problems associated with hay making would be solved if hay drying time could be red~ced or if hay could be stored at high mOIsture (HM) without spoilage. When hay is baled at greater than 20% moisture, molds and fungi can grow, and excessive heating can occur; this has resulted in reduced apparent

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MICROBIAL INOCULANT AND FORAGE QUALITY

digestibilities of OM, CP, and ADF (3, 8, 10, 11, 17). Organic acids, such as propionic acid (9), anhydrous ammonia (16), and urea (1, 3), have been used to prevent heating and mold growth in HM hay during storage. The corrosive effect of organic acids on equipment and the potential risk to the operator make their use unpopular. Urea, although effective as a fungicide and preservative (1, 3), can be expensive. Recently, microbial inoculant PII55 (pioneer HiBred Microbial Genetics Division, Des Moines, IA) containing Bacillus pumulus was developed for preservation of HM alfalfa hay. The advantage of this inoculant is that it is noncorrosive and easy to mix and to apply. If PII55 has fungicidal action, it should reduce heating and mold growth during storage of HM hay. The objectives of this trial were 1) to determine whether a microbial hay inoculant (PI155) was effective in preserving hay baled at 28 and 25% moisture as evaluated by chemical composition and animal performance and 2) to determine whether treatment of HM hay with a microbial inoculant affects the apparent digestibility of OM, ADF, NDF, and CP by lambs compared with uninoculated HM hay. MATERIALS AND METHODS

During 1989 and 1990, alfalfa hays were harvested and stored as small rectangular bales, with an average weight of 20 kg, on a commercial New Jersey dairy farm. During yr 1, third-cutting alfalfa hay was baled at either 18% Oow moisture; LM) or 28% (HM) moisture. At the time of baling, approximately 5000 kg (250 bales) of the 28% HM hay were treated with PII55. All three hays were stored in a metal hay barn with a dirt floor. Bales were stacked in blocks of 192, eight bales high, four bales across, and six bales deep. Moisture was determined just prior to baling on windrow samples using a microwave oven. In yr 1, all three hays were harvested from two fields. During yr 2, at the same location, two fields containing second-cutting alfalfa were harvested and baled at either 18% (LM) or 25% (HM) moisture. As in yr 1, approximately 5000 kg (250 bales) of the HM hay were treated with the microbial inoculant at baling. In both years, the inoculant was applied at a

3085

rate of 3.8 U.98 tonne of wet hay. At this application rate, 90 million cfu/tonne of forage were applied. Inoculant was sprayed onto the forge as it passed over the pickup mechanism of the baler. Ten bales per field were core sampled and composited by treatment and by field at each sampling day. Hays were sampled on d 0, 14, 30, and 60 following baling. In yr 1, CP, ADF, ADIN, NDF, Ca, P, and Mg concentrations were determined in duplicate on the core samples. In vitro OM digestion and in vitro NDF digestion were determined on 30- and 60-d core samples (12, 14). During yr 2, CP, ADF, and NDF concentrations were determined on core samples and net energy for gain was predicted using the regression equations of the Northeast DHIA Forage Testing Laboratory (Ithaca, NY). In both years, OM, CP (N x 6.25), Ca, and Mg were determined by standard procedures (2). The ADF and ADIN concentrations were determined by standard procedures (4). The NDF concentration was determined without decalin or sodium sulfite (6). Phosphorus was measured colorimetrically (7). The statistical model for analysis of hay composition data contained field, sampling day, and treatment as main effects. The interaction of field by treatment was not significant. Performance Trial

Twelve Dorset wether Iambs with an average weight of 20 kg were assigned to three dietary treatments in a replicated 3 x 3 Latin square design. Dietary treatments consisted of a TMR containing 63% chopped hay and 35% ground com, plus minerals and vitamins (Table 1). The chopped hay was either LM alfalfa hay baled at 18% moisture, HM alfalfa hay baled at 25% moisture, or HM alfalfa hay treated with the microbial inoculant at baling. The TMR was fed in individual self-feeders, and orts were taken weekly. Orts samples were analyzed for OM, CP, ADF, and NDF. Within each 28-d period, performance data on d 1 to 18 were collected. During the performance phase of each period, the diets were offered for ad libitum intake. and lambs were weighed on d 1, 2, 17, and 18 of each period. Initial and Journal of Dairy Science Vol. 75, No. 11, 1992

3086

EMANUELE ET AL.

TABLE 1. Ingredient and chemical composition of TMR.l

INH TMR

HM

Ingredient

LM TMR

Chopped alfalfa hay Ground com Dicalcium phosphate Limestone NaCI Mineral premix 2

63.30 35.30 .15 .44 .44 .30

63.30 35.30 .15 .44 .44 .30

63.30 35.30 .15 .44 .44 .30

Chemical composition, % CP 13.00 ADF 31.13 NDF 40.02 Ca .65 P .32 Na .22 Mg .20

12.80 31.19 40.27 .65 .32 .22 .20

12.90 32.58 40.27 .65 .32 .22 .20

TMR

(% of DM)

lLM =Low moisture hay baled at 18% moisture; INH = inoculated high moisture hay baled at 25% moisture; HM = high moisture hay baled at 25% moisture. 2Mineral premix composition (Agway Inc., Syracuse, NY): Ca, 20%; NaCI, 41.5%; Co, .06%; I, .07%; Mo, 8.0%; Zo, 1.6%; Se, .09%.

final weights were based on averages of weights taken on d 1 and 2 and 17 and 18, respectively. These average weights were used to compute the rate of gain of each lamb. Lambs were not feed restricted prior to weighing but had access to feed and water. Lambs were weighed at the same time each day. Individual lamb weights taken on consecutive days differed by a maximum of .7 kg. On d 19 to 28 of each period, lambs were placed into metabolism crates. During the digestion trial, feed intake was restricted to 70 glkg of BW·75 to reduce sorting of the TMR by the lambs. Lambs were allowed 3 d to adapt to metabolism crates prior to each 7-d fecal and urine collection. During the digestibility trial, lambs were fed once daily, and samples of orts were taken daily and composited. Perfonnance criteria measured were DMI; average daily gain; feed to gain ratio; and protein, ADF, and NDF intakes. Intakes of DM, CP, ADF, and NDF were computed as quantity offered minus orts. The DM, CP, ADF, and NDF concentrations were measured in feed, orts, and fecal samples by the same methods used to determine hay composition. Journal of Dairy Science Vol. 75, No. II, 1992

Apparent digestion was determined by total fecal collection. Statistical analysis was perfonned using a general linear models procedure (13). The model contained the following main effects: square, period, treatment, animal nested within square, and residual. Means comparison was by least significant difference protected by a significant F value (P < .05). (13). Significance was declared at P < .05 unless otherwise noted. RESUL1S AND DISCUSSION

In yr 1, differences were not significant for percentages of CP, ADF, NDF, or ADIN, in vitro OM digestion, or in vitro NDF digestion between LM hay or HM hay treated with microbial inoculant (Table 2). Although the ADIN concentration was not different among the hays, the percentage of the total CP associated with the ADF was 9% greater in HM hay than in LM hay, 33.42 and 30.47%, respectively. The inoculated hay was intermediate between the other hays; 31.05% of the CP was associated with ADF. Available protein, calculated as total CP minus ADIN expressed as a percentage of the total protein, was not different for the three hays because of the small number of observations. However, the available protein content of HM hay was 13% lower than that of LM hay and 9% lower than the inoculated hay. These observations suggest that all of the hays underwent some heating during storage. The extent of heat damage was least in LM hay, followed by the inoculated hay and HM hay. Uninoculated HM hay had a greater concentration of ADF and NDF but lower concentration of CP compared with inoculated HM hay. Inoculated HM hay had greater in vitro OM digestibility than uninoculated HM hay. In yr 2, CP and NDF percentages were not different among hays, but uninoculated HM hay had greater ADF content than inoculated HM hay (P < .10). Differences noted between years were due to different growing conditions and time of harvest. Year 1 was a wet year; the third-cutting alfalfa was harvested August 24, 1989, about 2 wk later than usual. The fields contained approximately 20% fall panicum (Panicum dichotomiflorum) as a weed among the alfalfa. Both the alfalfa and fall panicum were stemy, based on visual observation. In yr 2, fall panicum was not a

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MICROBIAL INOCULANT AND FORAGE QUALITY

major problem at harvest, which may explain why NDF content was greater in yr 1 than in yr 2. Year 2 was drier and hotter than yr 1; the second cutting was harvested July 13, 1990. Conditions on the day of baling during yr 2 were sunny and dry. During the baling, the hay dried rapidly. There was less visible heating of the hay during storage in yr 2 than in yr 1. In yr 1, steam could be seen to escape from the uninoculated HM hay during the fIrst 14 d of storage. By d 30 of storage, the hay had turned dark brown. In yr 2, heating during storage was not as extensive as in yr 1, because the color of uninoculated HM hay was tan to yellow and not much darker than LM hay. Visible observation of open bales indicated that heating was not excessive during yr 2, because the center of the bales were not dark brown as in yr 1. When spontaneous heating

occurs, the concentration of ADF in the forage increases, but the concentration of hemicellulose decreases (5). Lignin also increases in forages that undergo heating during storage (15). In yr 1 and 2, ADF concentration in HM hay increased by 5.2 and 4.6% compared with the LM hay, but only in yr 1 was NDF percentage increased (16.8%) in HM hay compared with LM hay. Our results agree with other studies (1, 10, 11) that reported greater ADF and NDF concentrations in forages baled at HM versus LM. In vitro NDF digestibility was greater for HM hay than for LM hay or for inoculated HM hay. Moisture percentage at baling had a smaller effect on chemical composition in yr 2 than in yr 1, which probably was due to weather conditions at baling. On the day of baling in yr 2, the air temperature was between

TABLE 2. Effect of a microbial hay inoculant on the chemical composition of alfalfa hay core samples. Treatment! LM Hay

Item

Inoculated hay

HM Hay

SE

- - - - - - (%. DM basis) - - - - - -

Year 1 .37 .58 2.13 .54 .29

.23b

14.20b 9.45 33.42 40.4Q8 4.60 n.2(Y; 51.2Ob 57.00" .54d .30& .38a

14.60 47.6()f 58.60 .42a

14.70 49.80" 58.60 .37b

.32

15.60" 10.86 30.47 38.30b 4.76 60.l()d 56.80" 48.6Qb .63c .24b .23b

15.10" 10.38 31.05 38.2Ob 4.67 6O.l()d 54.10" 48.3Ob .66c .26b

a

14~

ADF NDF Predicted NEg,4

47.5()f 58.20 .44a

CP Available CP Unavailable protein, % of total CP ADF ADIN NDF

IVOMD2 IVNDF3 Ca P Mg

1.16

1.24 2.10 .02 .01 .03

Year 2

Mcallkg

.74

.53 .02

a,b,c,d,e.t"Means in same row differ when superscripts are different. a,bp

< .05.

c.dp < .01.

< .10. !LM = Low moisture hay baled at 18% moisture, INH = inoculated hay baled at 28% moisture yr 1 and 25% moisture during yr 2, and HM = high moisture hay baled at 28% moisture yr 1 and 25% moisture during yr 2, and not treated with e.fp

inoculant. 2In vitro OM digestibility. 3In vitro NDF digestibility. 4Net energy for gain (NEg) predicted from ADF percentage:

Effect of microbial inoculant on quality of alfalfa hay baled at high moisture and lamb performance.

The effectiveness of a microbial hay inoculant in high moisture alfalfa hay was evaluated. Alfalfa (third cutting) was baled at 72% DM without or with...
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