Evaluation of Sweet Corn Residue as Roughage for Dairy Heifers1

Evaluation of Sweet Corn Residue as Roughage for Dairy Heifers 1 E. H, J A S T E R , 2 D. F. B E L L , 2'3 and G. C. M c C O Y 2 University o f Illinois Urbana 61801

ABSTRACT

resulted in higher nutrient digestibilities of sweet corn residue by dairy heifers.

Sweet corn residues as roughage for dairy heifers was evaluated alone and as a 50:50 mixture (dry matter) with corn silage against corn silage alone. Concentrations of neutral detergent fiber, acid detergent fiber, acid detergent lignin, hemicellulose, cellulose, and organic acids were greater for sweet corn residue, but dry matter concentration was less than corn .silage. Heifers fed sweet corn residue free choice consumed it at 1.5% of body weight. The mixture and corn silage alone were provided at equal intakes of dry matter. Apparent digestibility of dry matter (59.1 versus 69.7%) of sweet corn residue alone was lower than corn silage alone. Heifers consuming the mixture had increased digestibilities of dry matter, acid detergent fiber, acid detergent lignin, and crude protein over sweet corn residue alone. Heifers fed corn silage had lower rumen acetate and higher propionate concentrations than heifers fed sweet corn residue. Heifers consumed dry matter at 1.4% of body weight when offered sweet corn residue for ad libitum consumption. A restricted diet of corn silage alone was provided to heifers at equal the dry matter intake provided by sweet corn residue. Average daily gain was lower (.28 versus .79 kg) and ratio of feed to gain higher (21.4 versus 7.5) for feeding of the sweet corn residue diet alone. Heifer growth by heart girth was less for animals consuming sweet corn residue. Feeding a mixture of 50% sweet corn residue with 50% corn silage mixture

INTRODUCTION

In certain areas of Illinois, significant amounts of sweet corn are grown, providing quantities of sweet corn residues, of husks, cobs, cull ears, and part kernels. Sweet corn residue usually is ensiled either in stacks close to a processing factory or in bunker silos on individual livestock farms. Sweet corn residue contains 23% dry matter (DM), 8.8% crude protein, 27% crude fiber, and 65% total digestible nutrients (7). It is high in moisture (77%), contains considerable quantities (12.32% dry matter) of acid (10), and may be unpalatable to cattle (7). Researchers at the Delaware experiment station reported the use of sweet corn residue as a byproduct feed for milk cows (20). The residue was fed at 18 kg/day and contained .4 kg protein, 3.9 kg carbohydrates and fiber, and .07 kg oil. Sweet corn residue fed to dairy cattle had digestibilities of 31.9% for DM, 7.7% for crude protein, 39.9% for nitrogen-free extract, 24.4% for crude fiber, and 42.5% for crude fat (9). However, greater digestibilities (68% for dry matter, 56.5% for crude protein, 71% for nitrogen-free extract, 70% for crude fiber, and 87% for ether extract) were reported when steers were fed ensiled sweet corn residue (10). Analysis of corn residue indicated that the husk had the highest digestibility (19). Our purpose was to evaluate sweet corn residue as an ensiled roughage source for dairy heifers. MATERIALS

Received March 15, 1983. 1Supported by the Illinois Agricultural Experiment Station as part of Regional Research Project NC-143, "Optimizing the Nutritional Utilization of Forages by Dairy Cattle". 2Department of Dairy Science. 31332 Tenaya Drive, San Jose, CA 95125. 1983 J Dairy Sci 66:2349-2355

AND METHODS

Sweet corn residue was obtained from a bunker silo on a local livestock farm, transported to the University of Illinois dairy farm, and fed within 3 days of transport. Trial 1

Twelve Holstein heifers averaging 362 kg were assigned randomly to three groups.

2349

2350

JASTER ET AL.

Animals in each group were fed individually a sequence of three diets for three successive 21-day periods in a replicated 3 x 3 Latin square with four animals per group. Sweet corn residue was fed to all heifers during a 7-day pre-experimental period to determine ad libitum feed intake. One of the diets consisted of sweet corn residue fed for ad libitum consumption (10% feed refusal). The other two diets were a mixture of 50% sweet corn residue with 50% corn silage (DM) and corn silage alone. Feed intake was restricted in the latter two diets to ensure that intake of DM was equivalent to the sweet corn residue diet. All diets were fed once daily at 1200 h. All diets at feeding were isonitrogenous (approximately 11% crude protein) after addition of soybean meal to corn silage and the 50% sweet corn residue:50% corn silage. A mineral supplement containing dicalcium phosphate (54.3%), limestone (27.7%), and salt (17.0%) was fed to each heifer at .13 kg/day. Feed intake was recorded daily. Animals were provided free access to water and normally allowed to exercise for 60 min in an outside lot beginning at 1100 h. Feed was collected weekly during the experiment, and fecal grab samples were taken during the final 3 days of each period at 0700 h. Feed and feces from each animal were composited separately, oven-dried at 55°C for 3 days, ground through a Wiley mill (2 mm screen), and analyzed for dry matter, neutral detergent fiber (NDF), acid detergent fiber (ADF), and 72% sulfuric acid detergent lignin (ADL) by methods of Goering and Van Soest (6). Concentrations of cellulose and hemicellulose were estimated by subtraction of ash and ADL from ADF and ADF from NDF. N i t r o g e n was determined by the Kjeldahl method (1), and crude protein content calculated as Kjeldahl N x 6.25. Acid-insoluble ash (AIA) marker was used for determination of nutrient digestibility coefficients (16). Rumen fluid samples were taken via stomach tube at 4 h postfeeding on day 19 of each period. Rumen fluid was acidified to pH 2 with 6N HC1, centrifuged, and stored at - 2 0 ° C pending volatile fatty acid (VFA) analyses. Samples of corn silage and sweet corn residue were squeezed in a silage press to obtain liquid for organic acid and pH analyses. An Orion 601A ionanlyzer was used to determine pH of silage liquid. The procedure of Journal of Dairy Science Vol. 66, No. 11, 1983

Salinitro and Muirhead (14) was used to analyze organic acid concentrations. A Hewlett-Packard Model 5830A gas chromatograph with autosampler was used. A column 1.8 m in length with a 4-mm i.d. and packed with Chromosorb WHP was used for the separations. Individual concentrations of VFA in rumen fluid were determined by a Vista 44 gas liquid chromatograph (Varian, Walnut Creek, CA) according to procedures of Erwin et al. (5). Statistical analyses were by the general linear model procedures (SAS Institute Inc., Raleigh, NC). Trial 2

Forty heifers were assigned randomly to two treatment groups. One group of heifers received a diet consisting of sweet corn residue fed for ad libitum consumption (10% feed refusals). The other group of heifers received a restricted diet of corn silage equivalent to the dry matter provided by sweet corn residue. Both diets were fed once daily (1200 h). Corn silage and sweet corn residue diets were isonitrogenous. Soybean meal and mineral additions were as in trial 1. Heifers were housed in separate pens in a free stall unit and diets were provided on a concrete feeding area adjacent to pens. Heifers were identified by individual ear tag number. Body weights and animal measurements (heart girth and wither height) were taken over a 3-day period at the start and at the end of a 70-day trial to evaluate performance of heifers fed the diets. Statistical analyses were also as in trial 1. RESULTS A N D DISCUSSION

Chemical compositions of feeds and diets are in Tables 1 and 2. Sweet corn residue contained 79% moisture (21% DM) and 7.1% ash. The NDF, ADF, ADL, and crude protein content of sweet corn residue, expressed as a percent of DM, were greater than for corn silage. Hemicellulose and cellulose concentrations in sweet corn residue were 28 and 35% greater than those of corn silage. Mixing sweet corn residue and corn silage together in a ratio 50:50 DM resulted in a diet intermediate to each in nutrient composition. Table 1 also presents organic acid concentrations and pH's for ensiled feedstuffs. The pH of sweet corn residue (3.9) was lower than that of corn silage (4.3); however, both

SWEET CORN RESIDUE AS ROUGHAGE

2351

TABLE 1. Chemical analyses of feeds. Roughage source Component

Sweet corn residue

Corn silage (%)

Dry matter Neutral detergent fiber (DNF) Acid detergent fiber (ADF) Acid detergent lignin (ADL) Crude protein Ash Hemicellulose a Cellulose b pH Acetic acid Propionic acid Butyric acid Lactic acid Succinic acid

21.0 59.4 37.4 5.8 10.8 7.1 22.0 32.5 3.9 1.0 .05 .02 8.2 .04

49.9 40.6 24.8 4.6 8.2 7.2 15.8 20.9 4.3 .51 .02 .01 6.2 .02

aNDF minus ADF. bADF minus ADL.

m a t e r i a l s ensiled well. Lactic acid c o n c e n t r a t i o n of s w e e t c o r n residue (expressed as p e r c e n t o f D M ) was 24% g r e a t e r t h a n f o r c o r n silage (8.2 as c o m p a r e d to 6.2%). C o n c e n t r a t i o n s o f b o t h acetic a n d b u t y r i c acids were t w i c e t h o s e o f c o r n silage. P r o p i o n i c a n d succinic acids were also in small a m o u n t s in b o t h feedstuffs.

Trial 1

I n t a k e data f o r d r y m a t t e r , c r u d e p r o t e i n , a n d f i b e r c o m p o n e n t s are in T a b l e 3. E q u i v a l e n t d r y m a t t e r f e e d i n g was to r e m o v e t h e e f f e c t o f large d i f f e r e n c e s of forage m o i s t u r e c o n c e n t r a t i o n s . High m o i s t u r e forages l i m i t i n t a k e of DM b y dairy c a t t l e (15). S w e e t c o r n residue

TABLE 2. Chemical composition of diets. Roughage source a Component

Sweet corn residue

50% Sweet corn residue: 50% corn silage

Corn silage

(%) Dry matter Neutral detergent fiber (NDF) Acid detergent fiber (ADF) Acid detergent lignin (ADL) Crude protein Ash Hemicellulose b Cellulose c

21.0 59.4 37.4 5.8 10.8 7.1 22.0 32.5

30.7 48.8 29.7 4.9 10.8 7.1 19.2 25.7

51.8 38.9 23.8 4.4 10.6 7.3 15.1 20.1

achemical composition after the addition of soybean meal and minerals to the 50% sweet corn residue:50% corn silage and corn silage diets. bNDF minus ADF. CADF minus ADL. Journal of Dairy Science Vol. 66, No. 11, 1983

ba

ee g~

TABLE 3. Mean nutrient intake and digestion coefficients for ensiled sweet corn residue and corn silage.

O

Roughage source go ,< ~q

< o Ox

Z 9

0o tao

Component

Sweet corn residue

50% Sweet corn residue:50% corn silage

Contrast a Corn silage

SE

Intake (kg/day) Dry matter (DM) Neutral detergent fiber (NDF) Acid detergent fiber (ADF) Acid detergent lignin (ADL) Hemicellulose c Cellulose d Crude protein Digestibility, % DM NDF ADF ADL Hemicellulose Cellulose Crude protein

5.5 3.3 2.05 .32 1.21 1.79 .59

5.6 2.7 1.66 .27 1.07 1.44 .60

5.6 2.2 1.33 .25 .86 1.13 .59

59.1 64.1 56,9 5.4 75.9 66.7 46.O

68.1 66.2 61.1 28.1 74.8 65.5 55.9

69.7 59.8 52.2 32.6 70,0 54.0 55.2

71.5 16.5 9.8 1.1 .8 6.6

70.8 16.6 10.4 1.3 .8 6.1

67.7 18.4 10.4 1.8 1.1 6.2

.07 .04 .02 .004 .02 .02 .03 1.2 1.5 1.3 2.7 2.7 1.4 1.3

Rumen fluid characteristics Acetate, molar % Propionate, molar % Butyrate, molar % Isovalerate, molar % Valerate, molar % Ammonia nitrogen, mg/dl

aA, sweet corn residue versus 50% sweet corn residue: 50% corn silage mixture; B, sweet corn residue versus corn silage. b N o t significant (P>.10). CNDF minus ADF. dADF minus ADL. *(P<.05).

.33 .35 .19 .06 .03 .57

A

B

NS b

NS

NS

NS

NS

NS

NS NS

NS *

NS NS NS

* * NS

NS NS

* NS

~q v~ 7~ ,q

SWEET CORN RESIDUE AS ROUGHAGE consumption of DM was 5.5 kg/day. This represents DM intake of approximately 1.5% of body weight. The relationship between water content of sweet corn residue and feed intake may be considered a function of structural volume as some plant water is contained within the cell wall structure. Addition of water to feed or rumen contents has little effect upon intake as it largely is absorbed and removed (15). However, the retention of water by the adsorbent effect of the coarse structural components of ingested forage can have an inhibitory effect on feed intake (18). Intakes of NDF, ADF, ADL, hemicellulose, and cellulose were higher (P<.05) for heifers fed sweet corn residue than fed corn silage alone. Heifers fed sweet corn residue consumed more NDF (33%), A D F (35%), ADL (22%), hemicellulose (29%), and cellulose (37%) than those fed corn silage alone. Bulky diets may limit feed intake by ruminants because of physical factors such as distension of the digestive tract (3). Intestinal fill could provide a more reliable long regulatory system limiting energy balance than the more changeable ruminal fill (2). Several workers have examined the relationship between observed organic matter intake and cell wall content (4, 11). Cell solubles rapidly disappear in the rumen and require minimal space whereas physical limitations of forage intake would be related to cell wall content (17). Trials utilizing sheep fed a standard forage indicated that forage intake was an inverse function of cell wall concentration in forage DM (11). In this study, sweet corn residue contained approximately 60% cell wall (NDF). Relative intakes of sweet corn residue would be predictably lower as compared with other standard forages with lower percentage cell wall. Diets were formulated to be isonitrogenous so intakes of crude protein were not different (Table 3). Digestibilities of DM, ADF, ADL, and crude protein were lower (P<.05) when heifers were fed sweet corn residues than 50% sweet corn residue:50% corn silage mixture (Table 3). Digestibility of NDF, hemicellulose, and cellulose of the sweet corn residue diet and of the mixture of 50% sweet corn residue with 50% corn silage were not different. Mixing sweet corn residue and corn silage together in equal ratios of DM at feeding increased digestibility of DM 13% as compared to feeding

2353

sweet corn residue alone. The mixture and the corn silage diet alone had similar digestibilities of DM, ADL, hemicellulose, and crude protein. Digestibilities of sweet corn residue DM, ADL, and crude protein were less (P<.05) than corn silage alone. Digestibilities of NDF and hemicellulose by heifers were similar for sweet corn residue and corn silage diets. Digestibility of cellulose of sweet corn residue was higher (P<.05); however, DM digestibility was lower (P<.05) than that of corn silage. Depression of digestibility is a function of competition between digestion and passage rates, the influence being greatest on the slower digesting fractions in the plant cell wall (17). Sweet corn residue contained 32% more NDF than did corn silage, which would contribute to a lower DM digestibility of sweet corn residue as compared to corn silage. Feeding heifers restricted diets of corn silage and the mixture of 50% sweet corn residue:50% corn silage influenced digestibility of these forages. Studies of the effect of intake restriction on digestibility of forages (12) agree that the noncell-wall constituents (cell contents) affect DM digestion only slightly whereas the major part of the depression of digestion of DM is accounted for by the cell wall. Correlation between amount of feed and digestibility of DM was negative (12). Ruminal volatile fatty acid data are also in Table 3. Heifers fed sweet corn residue and the mixture had similar molar percentages of acetate, propionate, butyrate, and valerate. Animals fed corn silage had lower acetate and higher propionate concentrations compared to heifers fed sweet corn residue alone. Heifers consuming corn silage had similar butyrate concentrations compared to sweet corn residue. An interaction between DM intake and fiber in diet resulted in an increase of ratio acetate:propionate for heifers fed sweet corn residue (4.3) compared to those fed corn silage (3.6). Higher acetate and lower propionate concentrations are characteristic of diets having high fiber concentrations (18). Content of ruminal ammonia nitrogen for heifers fed the various diets was similar (Table 3). Trial 2

Performance of dairy heifers is summarized in Table 4. Heifers were fed the sweet corn residue and corn silage diets as described in trial 1. Heifers consumed DM of sweet corn Journal of Dairy Science Vol. 66, No. 11, 1983

23 54

JASTER ET AL.

TABLE 4. Performance of dairy heifers fed corn silage and sweet corn residue. Roughage source Component

Sweet corn residue

No. of animals Days of feed Initial weight, kg Final weight, kg Daily gain, kg/day Heart girth, cm/day Wither height, cm/day

18 70 421.2 441.2 .28 .01 .06

Corn silage SE

SE

17.3 4.1 .03 .01 .009

18 70 414.0 469.7 .79" .09* .07

15,8 14,8 ,04 .008 ,008

*(P<.05).

residue at a p p r o x i m a t e l y 6 kg/day (1.4% of b o d y weight). The corn silage group was fed equivalent DM. In addition to factors affecting feed intake and digestibility described in trial 1, concern exists a b o u t the acidic ensiled sweet corn residue and its subsequent effect on palatability (7). Lactic acid concentration of sweet corn residue was 24% greater than for corn silage. High organic acid c o n c e n t r a t i o n s of silages reduced feed intake in e x p e r i m e n t s where organic acids were administered intraruminally (15). Buffer feeding will neutralize the acid (13) and increase intake of some feeds. Average daily gains (.28 versus .79 kg) were lower (P<.05) for heifers fed sweet corn residue as c o m p a r e d to those fed a restricted diet of corn silage. The ratio of feed to gain for heifers fed sweet corn residue was 21.4 as c o m p a r e d to 7.5 for those fed corn silage. The ratio of feed to gain for corn silagefed animals was similar to that in (8). Additional m e a s u r e m e n t s (heart girth, wither height) were taken to estimate effects of diets on heifer growth (Table 4). Heart girth m e a s u r e m e n t s indicated that growth was greater (P<.05) for heifers consuming corn silage as c o m p a r e d to sweet corn residue. G r o w t h was n o t different b e t w e e n heifer groups for wither height. CONCLUSIONS

Dairy heifers consuming a diet of 50% sweet corn residue:50% corn silage had higher DM, A D F , A D L , and crude protein digestibilities than animals consuming sweet corn residue alone. Similarly, corn silage diets resulted in larger digestibilities of DM, A D F , A D L , cellulose, Journal of Dairy Science Vol. 66, No. 11, 1983

and crude protein than did sweet corn residue. Chemical c o m p o s i t i o n of sweet corn residue limits in its use as a forage source for dairy heifers. L o w average daily gains and higher ratios of feed to gain for animals fed sweet corn residue are undesirable for maximizing heifer p e r f o r m a n c e and growth. However, feeding a 50% sweet corn residue: 50% corn silage m i x t u r e i m p r o v e d digestibility of dry matter, fiber, and protein by heifers c o m p a r e d to feeding sweet corn residue alone.

REFERENCES

1 Association of Official Analytical Chemists. 1970. Official methods of analysis, l l t h ed. Assoc. Offic. Anal. Chem., Washington, DC. 2 Baile, C. A., and J. M. Forbes. 1974. Control of feed intake and regulation of energy balance in ruminants. Physiol. Rev. 54:160. 3 Balch, C. C., and R. C. Campling. 1962. Regulation of voluntary intake in ruminants. Nutr. Abstr. Rev. 32:669. 4 Crampton, E. W., E. Donefer, and L. E. Lloyd. 1960. A nutritive value index for forages. J. Anim. Sci. 19:538. 5 Erwin, E. W., G. J. Marco, and E. M. Emery. 1961. Volatile fatty acid analysis of blood and rumen fluid by gas chromatography. J. Dairy Sci. 44:1768. 6 Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analyses, USDA Agric. Handbook 379, Washington, DC. 7 Jorgensen, N. A., and J. W. Crowley. 1972. Sweet corn. Page 17 in Corn silage for Wisconsin cattle. 8 Lomas, L. W., D. G. Fox, and J. R. Black. 1982. Ammonia treatment of corn silage. 1. Feedlot performance of growing and finishing steers. J. Anim. Sci. 55:909. 9 McCandlish, A. C. 1920. The digestibility of corn cannery refuse. J. Dairy Sci. 3:370.

SWEET CORN RESIDUE AS ROUGHAGE I 0 Nevens, W. B. 1934. Feeding value of silage from corn cannery refuse. Univ. Illinois Agric. Exp. Stn. Bull. No. 391, 28:106. 11 Osbourn, D. F., R. A. Terry, G. E. Outen, and S. B. Cammell. 1974. The significance of a determination of cell walls as the rational basis for the nutritive evaluation of forages. Proc. XII Int. Grassl. Congr. 3:374. 12 Riewe, M. E., and H. Lippke. 1970. Considerations in determining the digestibility of harvested forage. Page F--1 in Proc. Natl. Conf. Forage Eval. Util., Lincoln, NE. 13 Rogers, J. A., and C. L. Davis. 1982. Rumen volatile fatty acid production and nutrient utilization in steers fed a diet supplemented with sodium bicarbonate and monensin. J. Dairy Sci. 65:944. I4 Salinitro, J., and P. A. Muirhead. 1975. Quantitative method for GC analysis of short chain mono- and di-carboxylic acids in fermentation media. Appl.

23 55

Microbiol. 29: 374. 15 Thomas, J. W., L. A. Moore, M. Okamoto, and J. F. Sykes. 1961. A study of factors affecting rate of intake of heifers fed silage. J. Dairy Sci. 44:1471. 16 Van Keulen, J., and B. A. Young. 1977. Evaluation o f acid-insoluble ash as a natural marker in ruminant digestibility studies. J. Anim. Sci. 44:282. 17 Van Soest, P. J. 1965. Symposium on factors influencing voluntary intake of herbage by ruminants: Voluntary intake in relation to chemical composition and digestibility. J. Anim. Sci. 24:834. 18 Van Soest, P. J. 1982. Page 276 in Nutritional ecology of the ruminant. O & B Books, Inc., Corvallis, OR. 19 Vetter, R. L. 1973. Evaluation o f chemical and nutritional properties of crop residues. In Crop Residue Syrup., Univ. Nebraska, Lincoln. 20 Wilkenson, A. E. 1915. Page 186 in Sweet corn. Orange Judd Co., London.

Journal o f Dairy Science Vol. 66, No. 11, 1983