Nutritive Value of Potato Processing Wastes in Total Mixed Rations for Dairy Cattle1

Nutritive Value of Potato Processing Wastes in Total M i x e d Rations for D a i r y Cattle I CHRIS ONWUBUEMELI, 2 J. T. HUBER? K. J. KING, and C.O.L.E. JOHNSON Department of Animal Science Michigan State University East Lansing 48824

ABSTRACT

high intakes of potato waste and pH was increased. The shift in rumen fermentation when large amounts of potatoes were fed explains the depressed butter fat on these rations.

The nutritive value of wet potato processing waste for dairy cattle was determined in two experiments. In Experiment 1, rations contained, on a dry matter basis, O, 10, 15, and 20% potato waste and were substituted for high moisture corn in diets for 32 lactating Holstein cows for 12 wk. Substituting potato waste for corn did not significantly affect milk yield, milk composition, milk production persistency, or dry matter intake. Cows fed 20% potato waste tended to decrease in milk fat percent and to shift molar proportions of rumen volatile fatty acids toward a decrease in acetate: propiohate ratio. In Experiment 2, six steers were used in a 3 x 3 Latin square design to test digestibility and nitrogen utilization of potato waste substituted for high moisture corn at 0, 10, and 20% of the ration dry matter. A second group of four steers with rumen fistulas were used in a 4 × 4 Latin square to test rumen fermentation parameters. Diets contained 0, 10, 20, and 30% potato wastes and were similar to Experiment 1. Potato waste did not significantly affect digestibility of crude protein or dry matter, but at 20% substitution digestibility of acid detergent fiber decreased. Rumen ammonia, acetate, acetate to propionate ratios, and total volatile fatty acids were lower at

INTRODUCTION

Received September 13, 1984. 1Published with approval of the Director of the Agricultural Experiment Station as Journal Article No. 11411. 2Federal Livestock Department, Kano, Nigeria. 3Department of Animal Science, University of Arizona, Tucson, AZ 85721. 1985 J Dairy Sci 68:1207-1214

A large number of by-products of the food industry are used in livestock feed. Crop residues and by-products currently fed advantageously to livestock include corn stalks, apple pomace, beet pulp, corn distiller's grain, fresh carrots, small grain straws, sugarcane baggasse, and others (9, 10). By-products of potato processing have been used to a limited extent in cattle feeding (2, 3, 5). Depending on the processing plant, potato by-products may be potato pulp, peeling slivers, potato culls, potato chips, and fragments. Potato wastes are a disposal problem, but if properly incorporated into animal rations, they are valuable as livestock feed (12). About 1 million tons of potato wastes are produced annually in the US. Crude protein and fiber content of potato wastes vary greatly depending on processing methods and range between 4 and 8% and 1.6 and 17.5%, respectively (2, 3, 5). The pH of wastes falls rapidly to about 3.7 at which pH it remains stable for long periods. Starch losses of up to 56% may occur during storage due to enzymatic and bacterial action (3, 7). In the past, potato wastes or by-products were fed to livestock as potato meal or dried pulp. Because of large expenditures for drying, current interest is centered on utilization of wet wastes. Substitution of wet potato waste for concentrates in dairy feeds appears feasible, particularly with completely mixed rations. Data by Brown et al. (2) indicated that wet corn and potato chipping by-products may be fed to dairy cattle without adverse effects. Our

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ONWUBUEMELI ET AL.

study determined the feeding value for dairy cows of potato processing waste obtained from a processing plant in Michigan. MATERIALS AND METHODS

The potato processing waste (PPW) consisted, on a dry matter (DM) basis, of 60% peel and sludge, 30% raw potato screenings, and 10% cooked packaging wastes. Steam treatment was used for peeling of potatoes with no added alkali. Whole cull potatoes were minced to pieces less than 1 cm prior to delivery. Analysis of waste is shown in Table 1. The study consisted of two experiments: 1) one with lactating cows and 2) a digestibility and rumen metabolism trial with young, growing steers.

Experiment 1

Lactation Trial. Thirty-two lactating Holstein cows were blocked for milk yields during a 2 wk pretreatment and allotted to a randomized block design. There were four cows per block and eight per treatment. The four rations (A, B, C, and D) provided 0, 10, 15, or 20% PPW (of DM) as substitute for high moisture corn (HMC). All rations contained 25% corn silage, 25% haylage, and approximately 14% CP. Ingredient and chemical analyses of total mixed rations are in Table 2. For the 12-wk experimental period cows were fed twice daily and housed in confinement stalls at the Michigan State University Dairy Cattle Center. Orts were weighed once daily and feed was adjusted to allow for about 10% orts. Cows were milked twice daily and milk weights recorded. At biweekly intervals, a.m. and p.m. milk samples were composited and analyzed for fat, protein, and total solids. On

day 60 of treatment, rumen contents were sampled through a stomach tube and blood from the tail vein. Rumen contents were strained through four layers of cheesecloth, pH was taken, and 25 ml were acidified with .5 ml 50% sulfuric acid, centrifuged, and frozen at - 5 ° C until analyzed. Blood samples were collected in heparinized, oxalated tubes, and centrifuged at 800 × g and plasma was frozen at - 5 ° C until analyzed. Experiment 2

Ration Digestibility. In a 3 × 3 Latin square design six yearling steers were used to test digestibility and nitrogen utilization of rations in which PPW replaced HMC at 0, 10, or 20% of DM. Ingredient composition and analyses of total mixed rations are in Table 3. Steers, housed in metabolism stalls at the Michigan State University Beef Cattle Research Center, were adapted to the rations for 7 days, and feces and urine were collected for 5 days. Steers were weighed at 0800 h on the beginning and last day of each collection period. Rations were fed ad libitum once daily in the morning and feed and orts were sampled daily. Urine was collected in a metal funnel connected to plastic jars by rubber tubing. To each jar 50 ml concentrated sulfuric acid were added daily just after urine sampling for preventing nitrogen loss. Rumen Metabolism. Four steers fitted with rumen fistulas were used in a 4 × 4 Latin square design. Three rations were the same as in trial 1 and the fourth contained 30% of the DM as PPW (Table 3). All rations were fed at 5% in excess of consumption to ensure ad libitum intake. Steers were adapted to rations for 9 days, and on day 10 rumen contents were sampled at 0, 2, 4, and 8 h postfeeding. Samples were strained through four layers of cheesecloth into

TABLE 1. Chemical analysis of potato processing waste used in the study. Range Dry matter, % Crude protein, % DM1 Acid detergent fiber, % DM pH I DM = Dry matter. Journal of Dairy Science Vol. 68, No. 5, 1985

24.30--27.99 4.1 -- 6.6 4.6 -- 8.3 3.60-- 4.21

R

SD

26.00 5.00 6.00 3.96

1.4 1.1 1.40 .30

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T A B L E 2. Ingredient and chemical composition of rations used in the lactation experiment. Rations, % PPW ~ Ingredients

0

10

15

20

Corn silage, % o f DM 2 Haylage, % of DM High moisture corn, % of DM Protein supplement, 3 % of DM Trace mineralized salt, 4 % of DM PPW, % of DM

25 25 42 7 1 0

25 25 32 7 1 10

25 25 27 7 1 15

25 25 22 7 1 20

Chemical composition DM Crude protein Acid detergent fiber

48.15 14.25 19.63

44.12 14.17 19.65

40.70 14.23 19.70

36.70 13.97 19.73

PPW = Potato processing waste. 2 DM = Dry matter. 3 Guaranteed analysis: m i n i m u m crude protein, 44.0%; m a x i m u m crude fiber, 8.0%; m i n i m u m calcium, 2.9%; m i n i m u m phosphorus, 1.5%; m i n i m u m sodium chloride, 1.8%; m i n i m u m vitamin A, 15,000 USP units/lb (.45 kg); m i n i m u m vitamin D3, 3,000 USP units/lb (.45 kg); m i n i m u m manganese, .200%; m i n i m u m copper, .005%; m i n i m u m iodine, .007%. 4 Guaranteed analysis: m i n i m u m zinc, .350%; m i n i m u m iron, .030%; m i n i m u m cobalt, .005%; m i n i m u m salt, 96.00%.

p l a s t i c vials c o n t a i n i n g .1 m l m e r c u r i c c h l o r i d e to stop fermentation. The pH of rumen fluid was determined immediately, and 2 ml of rumen fluid were mixed with 2 ml of 10%

s o d i u m t u n g s t a t e a n d 2 m l 1 N s u l f u r i c acid. T h e m i x t u r e w a s c e n t r i f u g e d at 1 2 0 0 × g a n d the supernatant w a s f r o z e n at - 5 ° C until analyzed.

T A B L E 3. Ingredient and chemical composition of rations fed in digestibility and r u m e n fermentation experiment. Rations, % PPW I'2 0

10

20

30

Corn silage, % of DM 3 Haylage, % DM High moisture corn, % DM PPW, % DM Protein supplement, a % DM

25 25 43 0 7

25 25 33 10 7

25 25 23 20 7

25 25 13 30 7

Chemical composition DM Crude protein Ac id detergent fiber

50.17 14.13 19.53

46.05 14.07 19.61

43.05 14.01 19.74

36.60 13.77 19.77

Ingredients

1 PPW = Potato processing waste. Rations 0, 10, and 20 were fed in digestibility trial. All rations were fed in the r u m e n fermentation trial. 3 DM = Dry matter. 4 Guaranteed analysis: m i n i m u m crude protein, 44.0%; m a x i m u m crude fiber, 8.0%; m i n i m u m calcium, 2.9%; m i n i m u m phosphorus, 1.5%; m i n i m u m s o d i u m chloride, 1.8%; m i n i m u m vitamin A, 15,000 USP units/lb (.45 kg); m i n i m u m vitamin D3, 3,000 USP units/lb (.45 kg).

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Cbernical Analysis. Dry matter was determined on complete rations by comminuting in a food chopper and placing about 50 g of material in a forced-air oven set at 100°C for 24 h. For PPW and feces, DM was determined at 60°C for 48 h. Crude protein was determined on all samples by the macro-Kjeldahl method and acid detergent fiber by the method of Van Soest (19). Milk samples were analyzed for fat, protein, and total solids by infrared spectroscopy at the Michigan Dairy Herd Improvement Milk Testing Laboratory. Plasma glucose was determined by the glucose-oxidase method (15). Rumen fluid was analyzed for acetate, propionate, and butyrate by gas chromatography in a column packed with 10% SP 1200/ 1% phosphoric acid (H3PO4) on 100/120 chromosorb. Rumen ammonia was determined by the method of Chaney and Marbach (4). Statistical Analysis. Data were analyzed statistically by analysis of variance methods described by Gill (6) for randomized block, split plot, or Latin square designs.

RESULTS AND DISCUSSION Experiment 1

Lactation Trial. Ration DM decreased as percent PPW in the ration increased due to the higher moisture in PPW than HMC. There were no differences between treatments in mean DM

intakes. This contrasts with Brown et al. (2), who reported a significant decrease in DM intake as percent of corn-potato by-product in the ration increased. Total milk production, 4% fat-corrected milk, and milk production persistency were not different between control and PPW rations (Table 4). Milk production was highest at the highest PPW. This contrasts with Brown et al. (2) and may be attributed to the differential effect of PPW on DM intake in the two studies. However, the studies may not be directly comparable because Brown et al. (2) substituted more by-product (24 and 36% of ration DM). Moreover, their by-product was composed of both potato chipping and corn wastes. Milk fat percent tended to decrease with increased PPW. The decreasing trend in milk fat percent may be explained in part by low fiber in PPW. Also, about 10% of the PPW was cooked waste. Inclusion of steamed potatoes into lactating rations previously decreased milk fat percent (16). Milk protein percent was not different among treatments. Likewise, plasma glucose was not affected by treatments, and values were similar to those in the literature (1, 11). Cows fed PPW gained slightly more weight than controls but differences were small. Efficiency of feed utilization did not differ among treatments, suggesting that DM from potato waste is utilized as efficiently for milk production as that from HMC.

TABLE 4. Performance 1 of cows fed potato processing wastes (PPW).2

Items Milk yield, kg/day 4% Fat-corrected milk, kg/day Milk production persistency, 100 X treatment/pretreatment Milk fat, % Change in milk fat, %3 Milk protein, % Dry matter intake, kg/day Weight gain, kg/day Milk/dry matter, kg/kg Plasma glucose, mg/dl

0

Rations, % PPW 10 15

20

SEM

27.24 24.22

26.15 22.82

25.65 22.84

27.42 23.65

1.39 1.11

99.02 3.31 -.54 3.08 18.20 .47 1.51 60.54

94.65 3.20 -.57 3.05 19.00 .68 1.38 57.85

92.02 3.20 -.54 3.06 18.30 .70 1.44 60.63

98.94 3.01 -.82 3.10 18.7 .69 1.49 59.94

6.77 .14 .18 .07 2.78 .14 .06 1.89

1Values are means of treatments. : Eight cows per treatment for 12 wk. 3Pretreatment -- treatment_ Journal of Dairy Science Vol. 68, No. 5, 1985

NUTRITIVE VALUE OF POTATO PROCESSING WASTES

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TABLE 5. Rumen fermentation characteristicsI of cows fed potato processing wastes (PPW)fl '3 Rations, % PPW Items Total VFA, mad Acetate, mM Propionate, mM Butyrate, toM Ratio, acetate:propionate Rumen pH

0

10

15

20

SEM

76.0 48.6 17.1 10.2 2.93 7.08

73.6 46.7 17.4 9.6 2.75 7.03

78.9 51.1 18.2 9.4 2.90 7.03

78.8 48.5 20.1 10.2 2.57

5.36 3.5 1.9 .9 .17 .12

6.99

Values are means of treatments. Eight cows per treatment for 12 wk. a Means on same row were not significantly different (P>.05).

T h e r e w e r e no significant d i f f e r e n c e s bet w e e n t r e a t m e n t s in c o n c e n t r a t i o n s o f r u m e n acetate, p r o p i o n a t e , and b u t y r a t e , or in a c e t a t e : p r o p i o n a t e (C2 :C3) ratios (Table 5), b u t a t r e n d t o w a r d higher p r o p i o n a t e and l o w e r C2:C3 was n o t e d as PPW increased, w h i c h m a y have b e e n r e s p o n s i b l e f o r t h e decrease in milk fat p e r c e n t .

Experiment 2

Ration Digestibility. A p p a r e n t p r o t e i n digestibility was n o t d i f f e r e n t a m o n g rations (Table 6). N i c h o l s o n and Friend (13) r e p o r t e d 31% digestibility for c r u d e p r o t e i n in p o t a t o pulp fed to sheep" R y a n and Balls (14) isolated an inhibit o r to c h y m o t r y p s i n f r o m p o t a t o juice.

TABLE 6. Nutrient digestibility, nitrogen (N) balance, 1 weight change, and efficiency of feed utilization of steers fed potato processing wastes (PPW).a Rations, % PPW Items Dry matter (DM) intake, kg/day Apparent DM digestibility, % Apparent protein digestibility, % Acid detergent fiber digestibility, % N intake, g/day Urinary N, g/day Fecal N, g/day Digested N, g/day N retained, g/day Urinary N, % digested Fecal N, % digested N Fecal N, % N intake Weight gain, g/day Weight gain/DM digested, g/kg Weight gain/N digested, g/g

0 5.69 c 78.6 72.8 54.8 e 129.6 a 49.6 34.7 c 94.1 44.8 52.3 38.0 c 27.0 444.2 110. 0 5.1

10 5.78 c 79.3 74.4 54.9 e 124.8 a 43.2 32.0 c 90.7 51.2 43.8 35.5 d 25.8 541.6 130.0 6.2

20 4.45 d 80.4 71.3 48.6 f 99.2 b 32.0 29.6 d 70.1 38.4 48.0 40.9 f 28.7 430.8 130.0 4.6

SEM .4 1.26 2.03

2.66 6.4 11.2 1.47 8.1 12.8 15.57 3.58 2.02 148.3 40.0 1.47

a'bMeans in same row with different superscripts differ (P<.05). C'dMeans in same row with different superscripts differ (P<. 10). e'fMeans in same row with different superscripts differ (P<.25). 1Values are means of treamaents. 2 Six steers per treamaent in a 3 × 3 Latin square design. Journal o f Dairy Science Vol. 68, No. 5, 1985

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TABLE 7. Rumen fermentation characteristics I of steers fed potato processing wastes (PPW).2 Rations, % PPW Items Total VFA, 3 mM Acetate, mM Propionate, mM Butyrate, mM Acetate:propionate Rumen ammonia, mg/dl pH DMI, 4 kg/day

O

10

20

30

52.26 a 33.74 a 12.60 e 5.92 2.74 h 4.88 h 5.78 e 4.21 a

51.05 a 31.75 a 12.34 e 6.96 2.65 h 3.98 h 6.06 f 4.38 b

44.97 b 27.60 b 11.60 f 5.77 2.50 h 2.98 i 6.28 f 3.99 e

46.12 b 26.48 b 13.41g 6.23 2.01 i 2.35 i 6.13 f 3.17 d

SEM .36 .28 .08 .08 .16 .58 .20 .06

a'b'C'dMeans in same row with different superscripts differ (P<.025). e'f'gMeans in same row with different superscripts differ (P<. 10). h'iMeans in same row with different superscripts differ (P<.O05). 1Values are means of treatment that include all sampling times. Four steers/treatment in a 4 × 4 Latin square design. 3 VFA = Volatile fatty acids. 4 DMI = Dry matter intake.

The PPW tended to lower (P<.25) A D F digestibility. Previous studies with p o t a t o waste did not measure fiber digestibility. Diets high in readily digestible carbohydrates, which depress r u m e n pH, o f t e n decrease r u m e n pH and cellulose digestibility (17); however, r u m e n pH was not lowered by PPW. The PPW is primarily an energy source and contains an a m o u n t of starch similar to high m o i s t u r e corn for which it substituted. However, p o t a t o starch m a y have b e e n m o r e rapidly digested than corn starch. The depression in A D F digestibility might be associated with an increased rate of r u m e n f e r m e n t a t i o n . Differences b e t w e e n t r e a t m e n t s in DM digestibilities were small, but values rended to increase as PPW increased. P o t a t o pulp in sheep rations decreased fecal DM (13) and increased the digestible DM. Nitrogen Balance. Fecal nitrogen decreased (P<.10) at 20% PPW, but urinary nitrogen did not differ b e t w e e n t r e a t m e n t s (Table 6). Neither was nitrogen r e t e n t i o n affected. Nitrogen retained as percent of digested nitrogen was numerically higher for the PPW rations, b u t variation a m o n g t r e a t m e n t s was large. Daily weight gains and efficiency of DM and protein utilization were n o t affected by PPW addition to rations, nor was utilization of dietary DM or o f dietary protein. Journal of Dairy Science Vol. 68, No. 5, 1985

Ru m en Metabolism. Inclusion of 20 and 30% PPW decreased (P<.025) total r u m e n V F A , acetate, and acetate to p r o p i o n a t e ratios. Higher (P<.10) p r o p i o n a t e than on the control ration was observed for 30% but n o t 20% PPW (Table 7). The decrease in total tureen V F A at 20 and 30% PPW may be explained .by decreased DM intakes. T o t a l V F A increased with time after feeding and was inversely related to r u m e n pH (Table 8), which agrees with I-Ioogendoorn and Grieve (8). The shift in r u m e n ferm e n t a t i o n toward lower acetate and C~:C3 ratios at 20 and 30% PPW was associated with the decreased milk fat percent observed in E x p e r i m e n t 1. The higher percentages of dietary PPW decreased ( P < . 0 0 5 ) r u m e n a m m o n i a concentrations, which peaked 2 h postfeeding. A d d i t i o n of m o r e f e r m e n t a b l e carbohydrate, such as starch, to ruminant rations causes a decrease in r u m e n a m m o n i a (18) probably due to a greater uptake of a m m o n i a by r u m e n microorganisms in support of enhanced microbial growth. However, the lower V F A c o n c e n t r a t i o n s on high PPW contrasts with such an effect. Data f r o m this study indicate t h a t PPW can replace up to 20% of the grain in total m i x e d rations for lactating dairy cattle. However, milk fat m a y be depressed if 20% or m o r e of the ration DM comes f r o m PPW. Feeding up to 20%

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TABLE 8. Effect of time of sampling on volatile fatty acids (VFA) and pH of steers fed potato processing wastes (PPW). Post feeding Rations

0h

2h

4h

8h

0% PPW VFA, rnM pH

44.62

46.71 5.77

49.04 5.55

55.97 5.43

10% PPW VFA, mM pH

49.78 6.69

47.60 6.01

48.85 5.88

57.97 5.68

20% PPW VFA, mM pH

47.52 6.80

47.00 6.33

42.42 6.20

52.95 5.80

30% PPW VFA, mM pH

38.80 6.80

44.92 6.08

49.67

49.10 5.82

6.36

o f t h e ration DM as PPW will n o t adversely affect n u t r i e n t digestibility, b u t 20% or m o r e o f the ration DM as PPW m a y depress A D F digestibility and cause a shift in r u m e n f e r m e n t a t i o n t o w a r d higher C2 :C3 ratios. ACKNOWLEDGMENT

This s t u d y was partially s u p p o r t e d b y OreIda F o o d s , Inc., Boise, ID. REFERENCES

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for lactating cows on rumen volatile fatty acids and milk composition. J. Dairy Sci. 53:1034. 9 Huber, J. T., A. Hargreaves, C.O.L.E. Johnson, and A. Shanan. 1983. Upgrading residues and byproducts for ruminants. Page 203 in Wood and agricultural residues, research on use for feed, fuel and chemicals. J. Sohes, ed. Academic Press, New York, NY. 10 Klopfenstein, T., and F. G. Owen. 1981. Value and potential use of crop residues and by-products in dairy rations. J. Dairy Sci. 64:1250. 11 Kronfeld, D. S., R. L. Donoghue, F. M. Stearns, and R. H. Engle. 1982. Nutritional status of dairy cows indicated by analysis of blood. J. Dairy Sci. 65:1925. 12 Michigan State University. 1981. A decade of progress in Michigan potato production. Agric. Exp. Sm. Res. Rep. 407. 13 Nicholson, J.W.G., and D. W. Friend. 1965. The digestibility of potato pulp protein by some species of farm animals. Can. J. Anim. Sci. 45:39. 14 Ryan, C. A., and A. K. Balls. 1962. An inhibitor to chymotrypsin from Solanum tuberosum and its behaviour towards trypsin. Proc. Natl. Acad. Sci. (US) 48:1839. 15 Sigma Chemical Company. 1982. The enzymatic colorimetric determination of glucose in whole, plasma or serum at 425-475 nrn. Tech. Bull. 510. 16 Skjevdal, T. 1974. Potatoes and Swedes in the diet of ruminants. 1. Studies in lactating dairy cows. Agric. Univ. Norway, Dep. Anim. Nutr. Rep. No. 167. 17 Stewart, C. S. 1977. Factors affecting cellulolytic activity of rumen contents. Appl. Environ. Microbiol. 33:497. 18 Tagari, H., Y. Dior, I. Ascarelli, and A. Bondi. 1964. The influence of level of protein and starch Journal of Dairy Science Vol. 68, No. 5, 1985

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in rations for sheep on utilization of protein. Br. J. Nutr. 18:333. 19 Van Soest, P. J. 1963. Use of detergent in the analysis of fibrous feeds. II. A rapid method for determination of fiber and lignin. J. Assoc. Offic. Anal. Chem. 46:829.

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20 Woodman, H. E., and R. E. Evans. 1943. Further investigation of the feeding value of artificially dried potatoes: The composition and nutritive value of potato cossettes, potato meal, potato flakes, potato slices and potato dust. J. Agric. Sci. 33:1.