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Nutritional Value of Wet Corn Gluten Feed for Sheep and Lactating Dairy Cows
Nutritional Value of Wet Corn Gluten Feed for Sheep and Lactating Dairy Cows S. L. G U N D E R S O N , A. A. A G U I L A R , and D. E. JOHNSON Department of Animal Sciences J. D. OLSON Department of Clinical Sciences Colorado State University Fort Collins 80523 ABSTRACT
Experiments were conducted to determine digestibility of wet corn gluten feed in sheep and effect of wet corn gluten feed on DM intake, milk production, and milk composition by dairy cows. In Trial 1, six wethers were fed wet corn gluten feed at maintenance and ad libitum for determination of nutrient digestibility by the conventional 7-d total collection technique. The sheep ate 1.32 times maintenance at ad libitum intake and no significant differences were found in digestibility due to intake. Digestibilities of DM, organic matter, energy, CP, ether extract, ADF, NDF, and hemicellulose averaged 70.3, 73.0, 73.7, 78.3, 72.8, 51.4, 58.1, and 60.4%, respectively. Mean total digestible nutrients for both treatments was 70.3. In Trial 2, 12 Holstein cows in mid to late lactation were allotted to a 4 x 4 Latin square design. Cows were fed a total mixed ration twice daily. Wet corn gluten feed was fed at 0 (control), 10, 20, and 30% of the total ration DM. There were no significant treatment effects on DM intake, milk yield, or milk composition. Dry matter intake (kg/d), milk production (kg/d), and percent milk fat were 21.4, 22.9, and 3.71, respectively, for control; 21.4, 23.0, and 3.80 for the 10%; 21.0, 23.1, and 3.71 for the 20%; and 21.0, 23.2, and 3.89 for the 30% wet corn gluten feed. INTRODUCTION
A recent trend in livestock feeding has been the increased utilization of wet by-product
feeds. Considerable research has been conducted on the nutritional value of dried byproducts. However, data obtained from wet by-product digestibility and production trials is still limited, and reported results are not in total agreement. Consistency in nutrient composition of these feeds has been of major concern to livestock producers. Chase (1) and Droppo et al. (4) reported variable protein, DM, and mineral contents in samples collected from wet brewers grains and wet corn gluten feed (WCGF). Concern about WCGF also stems from the fact that the high moisture content of the feed may reduce DM intake (DMI). This is a problem when feeding rations already high in moisture, such as silage-based diets. Many studies have shown depressed DMI with decreased ration DM (10, 11, 13, 15, 23). Lahr et al. (13) concluded that lactating dairy cow rations below 60 to 65% DM depressed intake, whereas Hutjens (10) recommended a minimum ration DM of 50%. Several researchers have reported that WCGF fed to lambs (17, 21) and feedlot cattle (2, 6) did not depress animal performance. Furthermore, substitution of WCGF for more traditional feeds in rations for lactating dairy cows at 25 to 30% did not depress DMI or milk yields (3, 10, 14). Meanwhile, other researchers revealed that diets containing 30 to 40% WCGF depressed DMI and milk production (5, 14, 2 3). The objectives of this study were 1) to determine the digestibility of locally produced WCGF when fed to sheep at two intakes and 2) to determine the effect that WCGF has on DMI, milk production, and milk composition in lactating dairy cows. MATERIALS AND METHODS Trial 1
Received February 20, 1987. Accepted August 31, 1987. 1988 J Dairy Sci 71:1204-1210
Six crossbred wether lambs (48 kg) were fed a diet consisting of 100% WCGF in order to 1204
DIGESTIBILITY OF WET CORN GLUTEN FEED determine apparent digestibilities of DM, organic matter (OM), energy, CP, ether extract (EE), A D F , NDF, and hemicellulose. Lambs were housed in individual elevated metabolism crates and fed twice daily at ad libitum or maintenance. The WCGF was delivered three times per week in plastic-lined barrels and was stored in a cooler at 5°C. Whenever a new batch of feed was delivered, any leftover WCGF was discarded. A 2-wk adaptation phase was followed by a 7-d collection period. In order to prevent contamination of the feces, harnesses were used to collect the urine. The urine was funneled into 18.9-L jars by continuous vacuum. Collection jars were then emptied, and the urine discarded when necessary. Upon completion of the initial digestion trial, the amount fed was gradually decreased. The amount was based on an average live weight of 48 kg and an estimated WCGF metabolizable energy (ME) of 3.04 Mcal/kg DM (19). Sheep were fed at maintenance for 1 wk prior to collection. Feed, orts, and feces were collected, mixed, subsampled daily, and frozen. Prior to analysis, samples were dried at 60°C in a forced-air oven for 48 h. After drying, samples were air equilibrated, weighed, and ground through a l-ram screen (Wiley mill). Feed and fecal samples were analyzed for DM, gross energy, CP, EE, ash, Ca, P, K, Mg, and Na. Neutral detergent fiber and A D F were determined according to procedures of Goering and Van Soest (19). Hemicellulose content was determined by subtraction of A D F from NDF.
Trial 2
Twelve Hostein cows in mid to late lactation (190 d in milk) were allotted to a 4 × 4 Latin square design. Cows weighed an average of 638 kg and were 6 yr of age. During the three previous lactations, the average production of the cows was 9000 kg of milk with milk fat and protein tests of 3.75 and 3.1%, respectively. Cows were maintained in tie stalls. All diets were offered ad libitum as complete feeds with forage:concentrate ratios of 60:40. The hay to corn silage ratio was 1.59:1 on a DM basis. Feed was offered twice daily at 0630 and 1600 h in amounts that allowed for approximately 10% refusal. Cows received 0, 10, 20, or 30% of the total ration DM as WCGF. The WCGF
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replaced 0, 21.2, 40.2, and 60.1% of the hominy, and 0, 34.2, 71.1, and 100% of the soybean meal (SBM), respectively. Due to the high level of P in this b y p r o d u c t feed, the amount of limestone in the diets was increased with increasing amounts of WCGF in order to maintain a Ca to P ratio of no less than 1.4:1. The percent in the basal ration of whole cotton seed, alfalfa hay, oat hay, and corn silage was kept nearly constant for all treatments. Trace mineral salt remained constant for all treatments. The cows were milked three times daily in a 15-cow Trigon milking parlor and had free access to fresh water at all times. Wet corn gluten feed was delivered at approximately 8-d intervals and was stored in 192.3-L barrels. The WCGF was sampled weekly for DM analysis (60°C for 48 h). Upon arrival at the Colorado State University Dairy Center, the WCGF was packed in the barrels to eliminate exposure to air, thereby decreasing the amount and rate of spoilage. The basal ingredients (listed above) were mixed in a Harsh Mobile Mixer for at least 10 min once per day. Depending on treatment, varying amounts o f hominy, SBM, and WCGF were mixed with the basal feed. The combined ingredients were allowed to agitate in a stationary horizontal paddle mixer for approximately 7 rain. The total mixed ration was then weighed out for each cow, and the feed offered was recorded to the nearest .1 kg. The stationary mixer was cleaned between each treatment to prevent contamination. The four experimental periods consisted of a 14-d adaptation period followed by a 7-d collection period. During the 1-wk collection period, weights of milk, feed offered, and orts were recorded daily. Total mixed rations for a given treatment were sampled each day, frozen, and composited at the end of each period. Feed and orts were processed and analyzed in the same manner as in the sheep trial. Individual milk samples were collected from each cow three times daily during the 7-d collection period for a total of 21 samples per cow. Each bottle contained potassium dichromate to prevent oxidation, and all samples were kept refrigerated during the 7-d collection phase. Milk samples were analyzed by both the Central Colorado and Utah DHIA for fat, protein, SNF, and lactose by a Multispec Infrared Milk Analyzer. Somatic cell count was determined Journal of Dairy Science Vol. 71, No. 5, 1988
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by a Coulter Milk Cell Counter (Coulter Electronics, Inc., Hialeah, FL). R ESU LTS AND DISCUSSION Trial 1
Chemical composition of the WCGF fed to the wethers is in Table 1. Hemicellulose, the largest component of the fiber portion, composed 75% of the NDF fraction. Chemical composition of the WCGF used in this trial was quite constant. Dry matter, NDF, and hemicellulose values had the highest variation, having SE of 1.0 and 1.2. Mineral components, which are often extremely variable in by-product feeds, had the lowest SE values. Other research demonstrated that substantial by-product variability may occur (1, 4). Phosphorus, K, and Mg were higher than reported by the International Feedstuffs Institute (IFI) (8) and the United States-Canadian Tables of Feed Composition (24), whereas Ca, Na, and total ash were intermediate (Table 2). Net energy for lactation was computed from TDN values at maintenance according to the equation developed by Moe and Tyrrell (16) and from DE values (22). The latter values were corrected for intake effects at 3 times maintenance by multiplying by .92. Resulting NE ! values predicted by these two methods averaged 1.61 and 1.76 Mcal/kg DM (Table 3). The DE, NE1, and TDN for WCGF determined in this trial were lower than those reported by others (8, 18, 24). This is probably due to variation in nutrient content or production procedures. The percentages of crude fiber, EE, and ash were similar. However, other fiber measures were higher and CP lower in the present study when compared to recommendations in the IFI (8), NRC (18, 19), and the United States-Canadian Tables of Feed Composition (24) (Table 4). The higher fiber and lower protein content indicate different production conditions and result in the moderately lower nutrient digestibilities for the WCGF in the present trial (Table 2). Only slight, nonsignificant differences in digestibility occurred at the two intakes. Therefore, apparent digestibilities were averaged for both, and they represent values determined at or near maintenance. Apparent digestibilities of DM, OM, energy, and EE ranged from 70.3 to 73.7%; TDN averaged Journal of Dairy Science Vol. 71, No. 5, 1988
70.3%. Crude protein was 78.3% digestible. The hemicellulose component of the fiber was the most digestible, averaging 60%, whereas ADF averaged only 51% (Table 3). Sheep ate only 1.32 times maintenance at ad libitum intake; hence, digestibilities between ad libitum and maintenance intakes were not different. Jaster et al. (12) reported higher apparent digestibilities of WCGF DM, NDF, and hemicellulose by dairy heifers than the digestibilities of those nutrients in alfalfa haylage, oatlage, or sorghum-soybean silage. The DM, NDF, and hemicellulose digestion values in the present trial averaged 76.6, 69.2, and 80.6%, respectively; however, CP digestibility was similar. Firkins et al. (6) reported that digestibilities of DM, ADF, NDF, and hemicellulose were significandy higher for lambs fed WCGF compared to those consuming dry corn gluten feed (DCGF). Increasing amounts of WCGF in lactating dairy cow rations, which consisted of corn silage and ground corn-soybean meal, resulted in higher apparent digestibilities of NDF and hemicellulose (23). During the steeping process, corn is soaked in a dilute solution of sulfurous acid, resulting in increased availability of digestible hemicellulose in ruminants (20). This may account for the relatively high (60%) apparent digestibility of hemicellulose in the present trial. Staples et al. (23) also reported a 13% increase in digestibility of EE when the
TABLE 1. Chemical composition of wet corn gluten feed (dry matter basis). Item
%
DM Gross energy, Mcal/kg DM CP Crude fiber ADF NDF Hemicellulose Ether extract Ash Ca p K Mg Na
56.87 4.54 22.73 8.49 12.21 49.27 37.06 2.62 7.15 .33 1.30 1.92 .46 .59
1Data obtained from four batches of feed.
SEMi
1.18 .12 .75 "i;7 1.19 1.02 .04 .03 .01 .05 .15 .O2 .04
DIGESTIBILITY OF WET CORN GLUTEN FEED
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TABLE 2. Comparison of wet corn gluten feed nutritional values (% of dry matter). Composition of diet
US-Canada a
IFI 2
NRC a
Trial
CP ADF NDF CF Ether extract TDN Digestible energy, Mcal/kg NEI, Mcal/kg Ash Ca P Mg K Na
25.6 ... ... 9.7 2.4 83 3.66 1.91 7.5 .36 .82 .36 .64 1.05
25.7 10.8 37.8 7.5 3.0
25.0 ... ... 9.0 ... 82 3.61 1.89 ... .33 .86 .32 .67 1.06
22.7 12.2 49.3 8,5 2.6 70 3.35 1.76 7.2 .33 1.30 .46 1.92 .59
' 3146 1.80 6.9 .40 1.09 .35 .55 .17
United States-Canadian Tables o f Feed Composition (24). 2 International Feedstuffs Institute (8). 3 National Research Council (18, 19).
p e r c e n t a g e o f W C G F in t h e r a t i o n w a s i n c r e a s e d f r o m 0 t o 4 0 % . T h e e x t e n s i v e d i g e s t i o n o f EE m a y h a v e b e e n a r e s u l t o f t h e lipid e x t r a c t i o n p r o c e d u r e s during w e t milling t h a t could p o s s i b l y leave a r e a d i l y d i g e s t e d lipid r e s i d u e . D i g e s t i b i l i t y o f EE in o u r trial w a s 72.8%, which was lower than the 86.2% digestible EE r e p o r t e d b y S t a p l e s et al. ( 2 3 ) .
Throughout
the
trial,
the
wethers experi-
enced mild to m o d e r a t e diarrhea. The severity o f t h e d i a r r h e a w a s less at m a i n t e n a n c e , p e r h a p s d u e t o i n c r e a s e d r e t e n t i o n t i m e in t h e g a s t r o i n testinal tract, which allowed for m o r e water a b s o r p t i o n . In one study, dairy heifers fed W C G F ad l i b i t u m e x p e r i e n c e d m i l d d i a r r h e a , w h i c h w a s a t t r i b u t e d t o t h e h i g h CP a n d
TABLE 3. Nutrient apparent digestibility, TDN, and predicted NEI, of wet corn gluten feed fed to sheep at two intakes. Item
Maintenance
SE
Ad libitum
SE
Mean
SE 1
DM Organic matter CP ADF NDF Hemicellulose Ether extract Nitrogen-free extract TDN Energy DE, Mcal/kg DM NEI, 2 NEI, 3
70.32 72.92 79.15 51.58 57.80 59.88 73.15 73.84 70.46 73.34 3.33 1.61 1.74
1.12 .72 1.04 1.87 2.14 2.35 1.59 1.04 .89 1.O6 ... ... ...
70.21 72.97 77.38 51.25 58.80 60.88 72.50 74.29 70.11 74.13 3.37 1.60 1.77
.52 .87 .78 1.26 2.41 3.09 .77 .46 .39 .50 ... ... ...
70.27 72.95 78.26 51.42 58.10 60.38 72.83 74.07 70.29 73.74 3.35 1.61 1.76
.60 .50 .67 1.08 1.52 1.86 .85 .55 .46 .57 ... ... ...
1 Standard error of the mean based on six sheep at two intakes (12 observations). 2 Calculated according to the equation: NE 1 = .0245 TDN (% of DM) --.12. aCalculated according to the equation: NE 1 = .92 (.677 DE (Mcal/kg DM) - . 3 6 ) . Journal of Dairy Science Vol. 71, No. 5, 1988
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m i n e r a l c o n t e n t o f t h e feed (12). F i r k i n s e t al. (7) r e p o r t e d t h a t l a m b s f e d D C G F e x p e r i e n c e d mild diarrhea, w h e r e a s feeding W C G F r e s u l t e d in n o diarrhea. Trial 2
All diets were f o r m u l a t e d to m e e t t h e r e q u i r e m e n t s f o r a 680-kg dairy cow p r o d u c i n g 29.5 kg m i l k o f 3.9% f a t (18). D i e t i n g r e d i e n t s a n d c h e m i c a l analyses are s h o w n in T a b l e 4. E x p e c t e d c o m p o s i t i o n o f m i x e d diets was c o n f i r m e d b y analyses. As increasing a m o u n t s o f W C G F were a d d e d t o t h e t o t a l r a t i o n DM, calculated NE 1 decreased f r o m 1.75 Mcal/kg DM at c o n t r o l to 1.67 Mcal/kg at 30% W C G F . T o t a l digestible n u t r i e n t values f o l l o w e d t h e same t r e n d ,
decreasing f r o m 76.3 to 71%. Acid d e t e r g e n t f i b e r values c a l c u l a t e d f r o m N R C also decreased as m o r e W C G F was a d d e d to t h e diet, b u t CP a n d N D F increased. C r u d e p r o t e i n increased b e c a u s e of a decrease in l o w p r o t e i n feeds (i.e., c o r n silage, h o m i n y , a n d o a t h a y ) ; a n d N D F increased b e c a u s e o f t h e decrease in SBM, w h i c h c o n t a i n e d o n l y 14% N D F (Table 5). Diets originally were f o r m u l a t e d to b e i s o n i t r o g e n o u s (16% CP); h o w e v e r , actual m i x e d diet analyses r a n g e d f r o m 15.3 t o 16.0% CP, w h e r e a s calculated analyses r a n g e d f r o m 15.6 t o 16.0% ( T a b l e 4). All t r e a t m e n t s cont a i n e d a d e q u a t e CP to s u p p o r t p r o d u c t i o n , especially in light o f t h e high DMI. T o t a l digestible n u t r i e n t s , Ca, a n d P i n t a k e s e x c e e d e d N R C r e q u i r e m e n t s in all rations.
TABLE 4. Diet ingredients and chemical composition of experimental diets fed to lactating dairy cows. Wet corn gluten feed (% of DM) Ingredient
IFN ~
0
10
Whole cottonseed Alfalfa Corn silage Oat hay Hominy Soybean meal Limestone Trace mineral salt Wet corn gluten feed
5-13-749 1-00-059 3-02-823 1-03-280 4-02-887 5-04-604 6-02-632
8.9 18.3 19.4 12.6 32.1 7.6 .8
20
30
(% of diet dry matter)
Chemical analyses of mixed diet samples DM CP ADF NDF Hemicellulose Ca P
K Mg Na Calculated composition 2 CP ADF NDF Total digestible nutrients NEI, Mcal/kg
.3
8.8 18.2 19.3 12.5 25.3 5.0 1.0
8.7 17.8 18.9 12.2 19.2 2.2 1.1
.3
.3
.3
9.6
19.6
30.5
63.7 15.3 19.6 47.2 27.6 1.4 .7 1.7 .2 .9
61.2 15.8 22.0 50.5 28.5 1.2 .9 1.3 .3 .8
59.6 15.4 21.9 48.7 26.8 1.3 .9 1.4 .3 .7
56.6 16.0 19.6 49.5 29.9 1.4 1.0 1.7 .3 .7
15.63 24.70 49.18 76.29 1.75
15.66 24.66 49.61 74.39 1.72
15.67 24.46 50.15 72.75 1.69
15.95 23.92 50.37 70.95 1.67
• . .
International Feed Number. 2Calculated from NRC (23) feed ingredient table; wet corn gluten feed values from Trial 1.
Journal of Dairy Science Vol. 71, No. 5, 1988
8.3 17.0 18.0 11.7 12.8 ... 1.4
DIGESTIBILITY OF WET CORN GLUTEN FEED
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TABLE 5. Dry matter intake (DMI), milk production, and milk composition from dairy cows fed four levels of wet corn gluten feed (WCGF). Percent WCGF in total m~ed diets ~
DMI, kg/d DMI, % of body weight Actual milk yield, kg/d 3.5% FCM, kg/d Efficiency of production kg 3.5 FCM/kg DMI kg 3.5 FCMIMcal NE1 Milk composition, % Fat Protein Lactose SNF Total solids
0
10
20
30
RSD:
21.4 3.34 22.9 23.7
21.4 3.41 23.0 24.1
21.0 3.36 23.1 23.9
21.0 3.34 23.2 24.7
4.74 .46 11.50 10.77
1.11 .62
1.13 .65
1.14 .68
1.18 .69
.19 .11
3.71 3.36 4.83 8.99 12.70
3.80 3.28 4.91 8.80 12.60
3.71 3.23 4.89 8.74 12.45
3.89 3.28 4.92 8.89 12.78
.57 .38 .28 .56 .92
All diets on a dry matter basis. 2 RSD = Residual standard deviation.
There were no effects (P>.05) of diets on DMI, milk yield, 3.5% FCM yield, or milk composition, including percent milk fat, protein, lactose, total solids, and SNF (Table 5). There was a trend for increased milk yield and FCM (23.7 to 24.7 kg/d) as the amount of WCGF increased in the ration. This trend occurred even though DMI was slightly lower at both 20 and 30% WCGF. Therefore, apparent efficiency of milk production, expressed as kg 3.5 FCM per Mcal NEI, was highest for 30% WCGF, averaging .69 versus control values of .62. The nonsignificant increase in milk yield with increasing WCGF differs from other reports (3, 14). Milk fat percentage and percent lactose were highest at 30%, whereas percent protein and SNF were highest in cows fed the control diet. Similarly, others (3, 14, 23) have found a tendency for milk fat content to increase and percent protein to decrease at higher WCGF. Davis et al. (3) maintained that the higher milk fat test resulted from higher fiber intakes, which produced a rumen fermentation with a higher molar acetate:propionate ratio. Cows fed the 10 and 30% WCGF diets consumed the most NDF: 10.81 and 10.40 kg/d, respectively. These cows also had the highest percent milk fat: 3.80 and 3.89%. Cows receiving the control and 20% WCGF diets consumed less NDF and hemicellulose and had
lower milk fat tests (Table 5). Average feed intake of all cows was equivalent to 3.71 times maintenance based on an average estimated ration NE 1 of 1.71 Mcal/kg DM. Although not significant, actual DMI was slightly lower in cows fed the 30% WCGF diet than in cows fed the control diet. However, DMI as a percent of body weight was identical (3.34%) at both intakes (Table 5). Macleod et al. (14) reported that the substitution of WCGF for some of the corn and SBM tended to lower DMI. They also reported a depression of DMI when WCGF was introduced either gradually or rapidly into a total mixed ration. Linear decreases in DMI were observed by Staples et al. (23) when WCGF was introduced at 0, 20, 30, or 40% of the ration DM. The decreases in feed intake reported by both authors may have been related to the high moisture content of the diets. The diets used by Macleod et al. (14) contained less than the 50% DM minimum recommended by Hutjens (10) to maintain maximum DMI, and the 40% WCGF diet fed by Staples et al. (23) was only slightly above, containing 50.4% DM. The percentage of DM in the present trial decreased from 63.7% DM in the control diet to 56.6% DM in the 30% WCGF diet. In condusion, our results indicate that this type of WCGF can be fed to dairy cows in mid to late lactation at intakes as high as 30% of Journal of Dairy Science Vol. 71, No. 5, 1988
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ration DM without depressing DMI, milk production, or altering milk composition. ACKNOWLEDGMENTS
The authors wish to thank Coors BioTech Co., Johnstown, CO, for furnishing both the wet corn gluten feed and their financial support. Appreciation is also extended to the personnel from the Colorado State University Foothills Metabolic Laboratory and the Colorado State University Dairy Center. REFERENCES 1 Chase, L. E. 1982. Using by-product feedstuffs in ruminant rations. Pages 1 0 7 - 1 1 0 in Proc. Cornell Nutr. Conf., Ithaca, NY. 2 Cordes, C. S., J. A. Paterson, K. P. Coffey, L. W. Rogers, and J. P. Bowman. 1986. The effects of corn grain or wet or dry corn gluten feed supplementation of hay diets on rumen parameters and diet digestibility by beef cows. J. Anita. Sci. 63(Suppl. 1):440. (Abstr.) 3 Davis, C. L., C. Staples, G. C. McCoy, and J. H. Clark. 1983. Feeding value of wet corn gluten feed. Page 23 in Illinois dairy report. Univ. Illinois, Urbana-Champaign. 4 Droppo, T. E., G. K. Mcleod, and D. G. Grieve. 1985. Composition and storage characteristics of wet corn gluten feed. Can. J. Anita. Sci. 65:265. 5 Droppo, T. E., G. K. Mcleod, D. G. Grieve, and J. D. Summers. 1982. Feeding value of moist corn gluten feed for lactating dairy cows. J. Anim. Sci. 55:121. 6 Firkins, J. L., L. L. Berger, and G. C. Fahey, Jr. 1985. Evaluation o f wet and dry distillers grains and wet and dry corn gluten feeds for ruminants. J. Anim. Sci. 60:847. 7 Firkins, J. L., L. L. Berger, G. C. Fahey, Jr., and N. R. Merchen. 1984. Ruminal nitrogen degradability and escape o f wet and dry distillers grains and wet and dry corn gluten feeds. J. Dairy Sci. 67:1936. 8 Fonnesbeck, P. V., H. Lloyd, R. Obray, and S. Romesburg. 1984. IFI Tables o f Feed Composition. Int. Feedstuffs Inst., Utah State Univ., Logan. 9 Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analysis. USDA Agric. Handbook 379. Wash-
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ington, DC. 10 Hutjens, M. F. 1982. Energy: First limiting nutrient. Pages 3 0 - 3 2 in Proc. Am. Feed. Manuf. Assoc. Nutr. Counc. 11 Hutjens, M. F., S. G. Bidner, and J. C. Weigel. 1984. Corn gluten feed for dairy cattle. Coop. Ext. Serv., Illinois-Iowa Dairy Guide No. 208. 12 Jaster, E. H., C. R. Staples, G. C. McCoy, and C. L. Davis. 1984. Evaluation o f wet corn gluten feed, oatlage, sorghum-soybean silage, and alfalfa haylage for dairy heifers. J. Dairy Sci. 67:1976. 13 Lahr, D. A., D. E. Otterby, D. G. Johnson, J. G. Linn, and R. G. Lundquist. 1983. Effects of moisture content of complete feeds on intake and milk production by cows. J. Dairy Sci. 66:1891. 14 Macleod, G. K-, T. E. Droppo, D. G. Grieve, D. J. Barney, and W. Rafalowski. 1985. Feeding value of wet corn gluten feed for lactating dairy cows. Can. J. Anita. Sci. 65:125. 15 Miller, W. J., C. M. Clifton, P. R. Fowler, and R. P. Gentry. 1967. Comparison o f low moisture and unwilted coastal Bermudagrass silages for lactating cows. J. Dairy Sci. 50:1262. 16 Moe, P. W., and H. F. Tyrrell. 1977. Estimating metabolizable and net energy of feeds. Pages 2 3 2 236 in Proc. 1st Int. Syrup. Feed Composition, Animal Nutrient Requirements, and Computerization of Diets, Logan, UT. 17 Morrical, D. G., D. D. Loy, and M. S. Honeman. 1986. Corn gluten feed and whole pressed sunflower seed as protein sources for feedlot lambs. J. Anim. Sci. 63(Suppl. 1):435. (Abstr.) 18 National Research Council. 1978. Nutrient requirements o f dairy cattle. 5th rev. ed. Natl. Acad. Sci., Washington, DC. 19 National Research Council. 1975. Nutrient requirements of sheep. Natl. Acad. Sci., Washington, DC. 20 Norman, A. G. 1935. The composition of crude fibre. J. Agric. Sci. 25:529. 21 Njoya, A., and A. Trenkle. 1986. Voluntary intake and digestibility of corn gluten feed by sheep. J. Anim. Sci. 63(Suppl. 1):454. (Abstr.) 22 Nutritional energetics of domestic animals and glossary of energy terms. 1981. 2nd rev. ed. Natl. Acad. Press, Washington, DC. p. 33. 23 Staples, C. R., C. L. Davis, G. C. McCoy, and J. H. Clark. 1984. Feeding value of wet corn gluten feed for lactating dairy cows. J. Dairy Sci. 67:1214. 24 United States-Canadian Tables o f Feed Composition. 1982. Nutritional data for United States and Canadian feeds. 3rd rev. Natl. Acad. Press, Washington, DC.
Experiments were conducted to determine digestibility of wet corn gluten feed in sheep and effect of wet corn gluten feed on DM intake, milk production, and milk composition by dairy cows. In Trial 1, six wethers were fed wet corn gluten feed at maintenance and ad libitum for determination of nutrient digestibility by the conventional 7-d total collection technique. The sheep ate 1.32 times maintenance at ad libitum intake and no significant differences were found in digestibility due to intake. Digestibilities of DM, organic matter, energy, CP, ether extract, ADF, NDF, and hemicellulose averaged 70.3, 73.0, 73.7, 78.3, 72.8, 51.4, 58.1, and 60.4%, respectively. Mean total digestible nutrients for both treatments was 70.3. In Trial 2, 12 Holstein cows in mid to late lactation were allotted to a 4 x 4 Latin square design. Cows were fed a total mixed ration twice daily. Wet corn gluten feed was fed at 0 (control), 10, 20, and 30% of the total ration DM. There were no significant treatment effects on DM intake, milk yield, or milk composition. Dry matter intake (kg/d), milk production (kg/d), and percent milk fat were 21.4, 22.9, and 3.71, respectively, for control; 21.4, 23.0, and 3.80 for the 10%; 21.0, 23.1, and 3.71 for the 20%; and 21.0, 23.2, and 3.89 for the 30% wet corn gluten feed. INTRODUCTION
A recent trend in livestock feeding has been the increased utilization of wet by-product
feeds. Considerable research has been conducted on the nutritional value of dried byproducts. However, data obtained from wet by-product digestibility and production trials is still limited, and reported results are not in total agreement. Consistency in nutrient composition of these feeds has been of major concern to livestock producers. Chase (1) and Droppo et al. (4) reported variable protein, DM, and mineral contents in samples collected from wet brewers grains and wet corn gluten feed (WCGF). Concern about WCGF also stems from the fact that the high moisture content of the feed may reduce DM intake (DMI). This is a problem when feeding rations already high in moisture, such as silage-based diets. Many studies have shown depressed DMI with decreased ration DM (10, 11, 13, 15, 23). Lahr et al. (13) concluded that lactating dairy cow rations below 60 to 65% DM depressed intake, whereas Hutjens (10) recommended a minimum ration DM of 50%. Several researchers have reported that WCGF fed to lambs (17, 21) and feedlot cattle (2, 6) did not depress animal performance. Furthermore, substitution of WCGF for more traditional feeds in rations for lactating dairy cows at 25 to 30% did not depress DMI or milk yields (3, 10, 14). Meanwhile, other researchers revealed that diets containing 30 to 40% WCGF depressed DMI and milk production (5, 14, 2 3). The objectives of this study were 1) to determine the digestibility of locally produced WCGF when fed to sheep at two intakes and 2) to determine the effect that WCGF has on DMI, milk production, and milk composition in lactating dairy cows. MATERIALS AND METHODS Trial 1
Received February 20, 1987. Accepted August 31, 1987. 1988 J Dairy Sci 71:1204-1210
Six crossbred wether lambs (48 kg) were fed a diet consisting of 100% WCGF in order to 1204
DIGESTIBILITY OF WET CORN GLUTEN FEED determine apparent digestibilities of DM, organic matter (OM), energy, CP, ether extract (EE), A D F , NDF, and hemicellulose. Lambs were housed in individual elevated metabolism crates and fed twice daily at ad libitum or maintenance. The WCGF was delivered three times per week in plastic-lined barrels and was stored in a cooler at 5°C. Whenever a new batch of feed was delivered, any leftover WCGF was discarded. A 2-wk adaptation phase was followed by a 7-d collection period. In order to prevent contamination of the feces, harnesses were used to collect the urine. The urine was funneled into 18.9-L jars by continuous vacuum. Collection jars were then emptied, and the urine discarded when necessary. Upon completion of the initial digestion trial, the amount fed was gradually decreased. The amount was based on an average live weight of 48 kg and an estimated WCGF metabolizable energy (ME) of 3.04 Mcal/kg DM (19). Sheep were fed at maintenance for 1 wk prior to collection. Feed, orts, and feces were collected, mixed, subsampled daily, and frozen. Prior to analysis, samples were dried at 60°C in a forced-air oven for 48 h. After drying, samples were air equilibrated, weighed, and ground through a l-ram screen (Wiley mill). Feed and fecal samples were analyzed for DM, gross energy, CP, EE, ash, Ca, P, K, Mg, and Na. Neutral detergent fiber and A D F were determined according to procedures of Goering and Van Soest (19). Hemicellulose content was determined by subtraction of A D F from NDF.
Trial 2
Twelve Hostein cows in mid to late lactation (190 d in milk) were allotted to a 4 × 4 Latin square design. Cows weighed an average of 638 kg and were 6 yr of age. During the three previous lactations, the average production of the cows was 9000 kg of milk with milk fat and protein tests of 3.75 and 3.1%, respectively. Cows were maintained in tie stalls. All diets were offered ad libitum as complete feeds with forage:concentrate ratios of 60:40. The hay to corn silage ratio was 1.59:1 on a DM basis. Feed was offered twice daily at 0630 and 1600 h in amounts that allowed for approximately 10% refusal. Cows received 0, 10, 20, or 30% of the total ration DM as WCGF. The WCGF
1205
replaced 0, 21.2, 40.2, and 60.1% of the hominy, and 0, 34.2, 71.1, and 100% of the soybean meal (SBM), respectively. Due to the high level of P in this b y p r o d u c t feed, the amount of limestone in the diets was increased with increasing amounts of WCGF in order to maintain a Ca to P ratio of no less than 1.4:1. The percent in the basal ration of whole cotton seed, alfalfa hay, oat hay, and corn silage was kept nearly constant for all treatments. Trace mineral salt remained constant for all treatments. The cows were milked three times daily in a 15-cow Trigon milking parlor and had free access to fresh water at all times. Wet corn gluten feed was delivered at approximately 8-d intervals and was stored in 192.3-L barrels. The WCGF was sampled weekly for DM analysis (60°C for 48 h). Upon arrival at the Colorado State University Dairy Center, the WCGF was packed in the barrels to eliminate exposure to air, thereby decreasing the amount and rate of spoilage. The basal ingredients (listed above) were mixed in a Harsh Mobile Mixer for at least 10 min once per day. Depending on treatment, varying amounts o f hominy, SBM, and WCGF were mixed with the basal feed. The combined ingredients were allowed to agitate in a stationary horizontal paddle mixer for approximately 7 rain. The total mixed ration was then weighed out for each cow, and the feed offered was recorded to the nearest .1 kg. The stationary mixer was cleaned between each treatment to prevent contamination. The four experimental periods consisted of a 14-d adaptation period followed by a 7-d collection period. During the 1-wk collection period, weights of milk, feed offered, and orts were recorded daily. Total mixed rations for a given treatment were sampled each day, frozen, and composited at the end of each period. Feed and orts were processed and analyzed in the same manner as in the sheep trial. Individual milk samples were collected from each cow three times daily during the 7-d collection period for a total of 21 samples per cow. Each bottle contained potassium dichromate to prevent oxidation, and all samples were kept refrigerated during the 7-d collection phase. Milk samples were analyzed by both the Central Colorado and Utah DHIA for fat, protein, SNF, and lactose by a Multispec Infrared Milk Analyzer. Somatic cell count was determined Journal of Dairy Science Vol. 71, No. 5, 1988
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by a Coulter Milk Cell Counter (Coulter Electronics, Inc., Hialeah, FL). R ESU LTS AND DISCUSSION Trial 1
Chemical composition of the WCGF fed to the wethers is in Table 1. Hemicellulose, the largest component of the fiber portion, composed 75% of the NDF fraction. Chemical composition of the WCGF used in this trial was quite constant. Dry matter, NDF, and hemicellulose values had the highest variation, having SE of 1.0 and 1.2. Mineral components, which are often extremely variable in by-product feeds, had the lowest SE values. Other research demonstrated that substantial by-product variability may occur (1, 4). Phosphorus, K, and Mg were higher than reported by the International Feedstuffs Institute (IFI) (8) and the United States-Canadian Tables of Feed Composition (24), whereas Ca, Na, and total ash were intermediate (Table 2). Net energy for lactation was computed from TDN values at maintenance according to the equation developed by Moe and Tyrrell (16) and from DE values (22). The latter values were corrected for intake effects at 3 times maintenance by multiplying by .92. Resulting NE ! values predicted by these two methods averaged 1.61 and 1.76 Mcal/kg DM (Table 3). The DE, NE1, and TDN for WCGF determined in this trial were lower than those reported by others (8, 18, 24). This is probably due to variation in nutrient content or production procedures. The percentages of crude fiber, EE, and ash were similar. However, other fiber measures were higher and CP lower in the present study when compared to recommendations in the IFI (8), NRC (18, 19), and the United States-Canadian Tables of Feed Composition (24) (Table 4). The higher fiber and lower protein content indicate different production conditions and result in the moderately lower nutrient digestibilities for the WCGF in the present trial (Table 2). Only slight, nonsignificant differences in digestibility occurred at the two intakes. Therefore, apparent digestibilities were averaged for both, and they represent values determined at or near maintenance. Apparent digestibilities of DM, OM, energy, and EE ranged from 70.3 to 73.7%; TDN averaged Journal of Dairy Science Vol. 71, No. 5, 1988
70.3%. Crude protein was 78.3% digestible. The hemicellulose component of the fiber was the most digestible, averaging 60%, whereas ADF averaged only 51% (Table 3). Sheep ate only 1.32 times maintenance at ad libitum intake; hence, digestibilities between ad libitum and maintenance intakes were not different. Jaster et al. (12) reported higher apparent digestibilities of WCGF DM, NDF, and hemicellulose by dairy heifers than the digestibilities of those nutrients in alfalfa haylage, oatlage, or sorghum-soybean silage. The DM, NDF, and hemicellulose digestion values in the present trial averaged 76.6, 69.2, and 80.6%, respectively; however, CP digestibility was similar. Firkins et al. (6) reported that digestibilities of DM, ADF, NDF, and hemicellulose were significandy higher for lambs fed WCGF compared to those consuming dry corn gluten feed (DCGF). Increasing amounts of WCGF in lactating dairy cow rations, which consisted of corn silage and ground corn-soybean meal, resulted in higher apparent digestibilities of NDF and hemicellulose (23). During the steeping process, corn is soaked in a dilute solution of sulfurous acid, resulting in increased availability of digestible hemicellulose in ruminants (20). This may account for the relatively high (60%) apparent digestibility of hemicellulose in the present trial. Staples et al. (23) also reported a 13% increase in digestibility of EE when the
TABLE 1. Chemical composition of wet corn gluten feed (dry matter basis). Item
%
DM Gross energy, Mcal/kg DM CP Crude fiber ADF NDF Hemicellulose Ether extract Ash Ca p K Mg Na
56.87 4.54 22.73 8.49 12.21 49.27 37.06 2.62 7.15 .33 1.30 1.92 .46 .59
1Data obtained from four batches of feed.
SEMi
1.18 .12 .75 "i;7 1.19 1.02 .04 .03 .01 .05 .15 .O2 .04
DIGESTIBILITY OF WET CORN GLUTEN FEED
1207
TABLE 2. Comparison of wet corn gluten feed nutritional values (% of dry matter). Composition of diet
US-Canada a
IFI 2
NRC a
Trial
CP ADF NDF CF Ether extract TDN Digestible energy, Mcal/kg NEI, Mcal/kg Ash Ca P Mg K Na
25.6 ... ... 9.7 2.4 83 3.66 1.91 7.5 .36 .82 .36 .64 1.05
25.7 10.8 37.8 7.5 3.0
25.0 ... ... 9.0 ... 82 3.61 1.89 ... .33 .86 .32 .67 1.06
22.7 12.2 49.3 8,5 2.6 70 3.35 1.76 7.2 .33 1.30 .46 1.92 .59
' 3146 1.80 6.9 .40 1.09 .35 .55 .17
United States-Canadian Tables o f Feed Composition (24). 2 International Feedstuffs Institute (8). 3 National Research Council (18, 19).
p e r c e n t a g e o f W C G F in t h e r a t i o n w a s i n c r e a s e d f r o m 0 t o 4 0 % . T h e e x t e n s i v e d i g e s t i o n o f EE m a y h a v e b e e n a r e s u l t o f t h e lipid e x t r a c t i o n p r o c e d u r e s during w e t milling t h a t could p o s s i b l y leave a r e a d i l y d i g e s t e d lipid r e s i d u e . D i g e s t i b i l i t y o f EE in o u r trial w a s 72.8%, which was lower than the 86.2% digestible EE r e p o r t e d b y S t a p l e s et al. ( 2 3 ) .
Throughout
the
trial,
the
wethers experi-
enced mild to m o d e r a t e diarrhea. The severity o f t h e d i a r r h e a w a s less at m a i n t e n a n c e , p e r h a p s d u e t o i n c r e a s e d r e t e n t i o n t i m e in t h e g a s t r o i n testinal tract, which allowed for m o r e water a b s o r p t i o n . In one study, dairy heifers fed W C G F ad l i b i t u m e x p e r i e n c e d m i l d d i a r r h e a , w h i c h w a s a t t r i b u t e d t o t h e h i g h CP a n d
TABLE 3. Nutrient apparent digestibility, TDN, and predicted NEI, of wet corn gluten feed fed to sheep at two intakes. Item
Maintenance
SE
Ad libitum
SE
Mean
SE 1
DM Organic matter CP ADF NDF Hemicellulose Ether extract Nitrogen-free extract TDN Energy DE, Mcal/kg DM NEI, 2 NEI, 3
70.32 72.92 79.15 51.58 57.80 59.88 73.15 73.84 70.46 73.34 3.33 1.61 1.74
1.12 .72 1.04 1.87 2.14 2.35 1.59 1.04 .89 1.O6 ... ... ...
70.21 72.97 77.38 51.25 58.80 60.88 72.50 74.29 70.11 74.13 3.37 1.60 1.77
.52 .87 .78 1.26 2.41 3.09 .77 .46 .39 .50 ... ... ...
70.27 72.95 78.26 51.42 58.10 60.38 72.83 74.07 70.29 73.74 3.35 1.61 1.76
.60 .50 .67 1.08 1.52 1.86 .85 .55 .46 .57 ... ... ...
1 Standard error of the mean based on six sheep at two intakes (12 observations). 2 Calculated according to the equation: NE 1 = .0245 TDN (% of DM) --.12. aCalculated according to the equation: NE 1 = .92 (.677 DE (Mcal/kg DM) - . 3 6 ) . Journal of Dairy Science Vol. 71, No. 5, 1988
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m i n e r a l c o n t e n t o f t h e feed (12). F i r k i n s e t al. (7) r e p o r t e d t h a t l a m b s f e d D C G F e x p e r i e n c e d mild diarrhea, w h e r e a s feeding W C G F r e s u l t e d in n o diarrhea. Trial 2
All diets were f o r m u l a t e d to m e e t t h e r e q u i r e m e n t s f o r a 680-kg dairy cow p r o d u c i n g 29.5 kg m i l k o f 3.9% f a t (18). D i e t i n g r e d i e n t s a n d c h e m i c a l analyses are s h o w n in T a b l e 4. E x p e c t e d c o m p o s i t i o n o f m i x e d diets was c o n f i r m e d b y analyses. As increasing a m o u n t s o f W C G F were a d d e d t o t h e t o t a l r a t i o n DM, calculated NE 1 decreased f r o m 1.75 Mcal/kg DM at c o n t r o l to 1.67 Mcal/kg at 30% W C G F . T o t a l digestible n u t r i e n t values f o l l o w e d t h e same t r e n d ,
decreasing f r o m 76.3 to 71%. Acid d e t e r g e n t f i b e r values c a l c u l a t e d f r o m N R C also decreased as m o r e W C G F was a d d e d to t h e diet, b u t CP a n d N D F increased. C r u d e p r o t e i n increased b e c a u s e of a decrease in l o w p r o t e i n feeds (i.e., c o r n silage, h o m i n y , a n d o a t h a y ) ; a n d N D F increased b e c a u s e o f t h e decrease in SBM, w h i c h c o n t a i n e d o n l y 14% N D F (Table 5). Diets originally were f o r m u l a t e d to b e i s o n i t r o g e n o u s (16% CP); h o w e v e r , actual m i x e d diet analyses r a n g e d f r o m 15.3 t o 16.0% CP, w h e r e a s calculated analyses r a n g e d f r o m 15.6 t o 16.0% ( T a b l e 4). All t r e a t m e n t s cont a i n e d a d e q u a t e CP to s u p p o r t p r o d u c t i o n , especially in light o f t h e high DMI. T o t a l digestible n u t r i e n t s , Ca, a n d P i n t a k e s e x c e e d e d N R C r e q u i r e m e n t s in all rations.
TABLE 4. Diet ingredients and chemical composition of experimental diets fed to lactating dairy cows. Wet corn gluten feed (% of DM) Ingredient
IFN ~
0
10
Whole cottonseed Alfalfa Corn silage Oat hay Hominy Soybean meal Limestone Trace mineral salt Wet corn gluten feed
5-13-749 1-00-059 3-02-823 1-03-280 4-02-887 5-04-604 6-02-632
8.9 18.3 19.4 12.6 32.1 7.6 .8
20
30
(% of diet dry matter)
Chemical analyses of mixed diet samples DM CP ADF NDF Hemicellulose Ca P
K Mg Na Calculated composition 2 CP ADF NDF Total digestible nutrients NEI, Mcal/kg
.3
8.8 18.2 19.3 12.5 25.3 5.0 1.0
8.7 17.8 18.9 12.2 19.2 2.2 1.1
.3
.3
.3
9.6
19.6
30.5
63.7 15.3 19.6 47.2 27.6 1.4 .7 1.7 .2 .9
61.2 15.8 22.0 50.5 28.5 1.2 .9 1.3 .3 .8
59.6 15.4 21.9 48.7 26.8 1.3 .9 1.4 .3 .7
56.6 16.0 19.6 49.5 29.9 1.4 1.0 1.7 .3 .7
15.63 24.70 49.18 76.29 1.75
15.66 24.66 49.61 74.39 1.72
15.67 24.46 50.15 72.75 1.69
15.95 23.92 50.37 70.95 1.67
• . .
International Feed Number. 2Calculated from NRC (23) feed ingredient table; wet corn gluten feed values from Trial 1.
Journal of Dairy Science Vol. 71, No. 5, 1988
8.3 17.0 18.0 11.7 12.8 ... 1.4
DIGESTIBILITY OF WET CORN GLUTEN FEED
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TABLE 5. Dry matter intake (DMI), milk production, and milk composition from dairy cows fed four levels of wet corn gluten feed (WCGF). Percent WCGF in total m~ed diets ~
DMI, kg/d DMI, % of body weight Actual milk yield, kg/d 3.5% FCM, kg/d Efficiency of production kg 3.5 FCM/kg DMI kg 3.5 FCMIMcal NE1 Milk composition, % Fat Protein Lactose SNF Total solids
0
10
20
30
RSD:
21.4 3.34 22.9 23.7
21.4 3.41 23.0 24.1
21.0 3.36 23.1 23.9
21.0 3.34 23.2 24.7
4.74 .46 11.50 10.77
1.11 .62
1.13 .65
1.14 .68
1.18 .69
.19 .11
3.71 3.36 4.83 8.99 12.70
3.80 3.28 4.91 8.80 12.60
3.71 3.23 4.89 8.74 12.45
3.89 3.28 4.92 8.89 12.78
.57 .38 .28 .56 .92
All diets on a dry matter basis. 2 RSD = Residual standard deviation.
There were no effects (P>.05) of diets on DMI, milk yield, 3.5% FCM yield, or milk composition, including percent milk fat, protein, lactose, total solids, and SNF (Table 5). There was a trend for increased milk yield and FCM (23.7 to 24.7 kg/d) as the amount of WCGF increased in the ration. This trend occurred even though DMI was slightly lower at both 20 and 30% WCGF. Therefore, apparent efficiency of milk production, expressed as kg 3.5 FCM per Mcal NEI, was highest for 30% WCGF, averaging .69 versus control values of .62. The nonsignificant increase in milk yield with increasing WCGF differs from other reports (3, 14). Milk fat percentage and percent lactose were highest at 30%, whereas percent protein and SNF were highest in cows fed the control diet. Similarly, others (3, 14, 23) have found a tendency for milk fat content to increase and percent protein to decrease at higher WCGF. Davis et al. (3) maintained that the higher milk fat test resulted from higher fiber intakes, which produced a rumen fermentation with a higher molar acetate:propionate ratio. Cows fed the 10 and 30% WCGF diets consumed the most NDF: 10.81 and 10.40 kg/d, respectively. These cows also had the highest percent milk fat: 3.80 and 3.89%. Cows receiving the control and 20% WCGF diets consumed less NDF and hemicellulose and had
lower milk fat tests (Table 5). Average feed intake of all cows was equivalent to 3.71 times maintenance based on an average estimated ration NE 1 of 1.71 Mcal/kg DM. Although not significant, actual DMI was slightly lower in cows fed the 30% WCGF diet than in cows fed the control diet. However, DMI as a percent of body weight was identical (3.34%) at both intakes (Table 5). Macleod et al. (14) reported that the substitution of WCGF for some of the corn and SBM tended to lower DMI. They also reported a depression of DMI when WCGF was introduced either gradually or rapidly into a total mixed ration. Linear decreases in DMI were observed by Staples et al. (23) when WCGF was introduced at 0, 20, 30, or 40% of the ration DM. The decreases in feed intake reported by both authors may have been related to the high moisture content of the diets. The diets used by Macleod et al. (14) contained less than the 50% DM minimum recommended by Hutjens (10) to maintain maximum DMI, and the 40% WCGF diet fed by Staples et al. (23) was only slightly above, containing 50.4% DM. The percentage of DM in the present trial decreased from 63.7% DM in the control diet to 56.6% DM in the 30% WCGF diet. In condusion, our results indicate that this type of WCGF can be fed to dairy cows in mid to late lactation at intakes as high as 30% of Journal of Dairy Science Vol. 71, No. 5, 1988
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ration DM without depressing DMI, milk production, or altering milk composition. ACKNOWLEDGMENTS
The authors wish to thank Coors BioTech Co., Johnstown, CO, for furnishing both the wet corn gluten feed and their financial support. Appreciation is also extended to the personnel from the Colorado State University Foothills Metabolic Laboratory and the Colorado State University Dairy Center. REFERENCES 1 Chase, L. E. 1982. Using by-product feedstuffs in ruminant rations. Pages 1 0 7 - 1 1 0 in Proc. Cornell Nutr. Conf., Ithaca, NY. 2 Cordes, C. S., J. A. Paterson, K. P. Coffey, L. W. Rogers, and J. P. Bowman. 1986. The effects of corn grain or wet or dry corn gluten feed supplementation of hay diets on rumen parameters and diet digestibility by beef cows. J. Anita. Sci. 63(Suppl. 1):440. (Abstr.) 3 Davis, C. L., C. Staples, G. C. McCoy, and J. H. Clark. 1983. Feeding value of wet corn gluten feed. Page 23 in Illinois dairy report. Univ. Illinois, Urbana-Champaign. 4 Droppo, T. E., G. K. Mcleod, and D. G. Grieve. 1985. Composition and storage characteristics of wet corn gluten feed. Can. J. Anita. Sci. 65:265. 5 Droppo, T. E., G. K. Mcleod, D. G. Grieve, and J. D. Summers. 1982. Feeding value of moist corn gluten feed for lactating dairy cows. J. Anim. Sci. 55:121. 6 Firkins, J. L., L. L. Berger, and G. C. Fahey, Jr. 1985. Evaluation o f wet and dry distillers grains and wet and dry corn gluten feeds for ruminants. J. Anim. Sci. 60:847. 7 Firkins, J. L., L. L. Berger, G. C. Fahey, Jr., and N. R. Merchen. 1984. Ruminal nitrogen degradability and escape o f wet and dry distillers grains and wet and dry corn gluten feeds. J. Dairy Sci. 67:1936. 8 Fonnesbeck, P. V., H. Lloyd, R. Obray, and S. Romesburg. 1984. IFI Tables o f Feed Composition. Int. Feedstuffs Inst., Utah State Univ., Logan. 9 Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analysis. USDA Agric. Handbook 379. Wash-
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