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Performance of Chicks Fed Different Levels of Potato Waste Silages1
Performance of Chicks Fed Different Levels of Potato Waste Silages1 E. A. SAUTER, C. F. PETERSEN, E. E. STEELE, and D. D. HINMAN Department of Animal Sciences, University of Idaho, Moscow, Idaho 83843 (Received for publication April 28, 1981) ABSTRACT Dried potato waste silages were fed to chicks in two experiments to determine whether residues or metabolites toxic to chicks were present. Silages were made from equal parts (v/v) "filter cake" and "dry peel" with chopped alfalfa hay (Experiment 1) or chopped barley straw (Experiment 2) added to 15% of the total to absorb excess moisture from the potato waste. Day-old broiler chicks were fed a corn-soybean meal (SBM) basal ration for 5 days in each experiment, sorted by weight, and experimental groups were equalized to within 1 g/chick. Chicks were then fed the basal ration or a ration containing silage at 5, 10, or 15% of the ration. All rations were isocaloric and isonitrogenous. Experimental rations were fed for 21 days in Experiment 1 and 14 days in Experiment 2. Chicks were group weighed at the start.at the termination, and at weekly intervals during each experiment. One-half the chicks from each ration were killed for examination of internal organs at the end of each experiment. After 2 weeks all silage fed groups weighed significandy (P<.05) less than controls in both experiments. At 3 weeks in Experiment 1 only chicks fed the 10% silage ration weighed significantly less than controls. Feed conversion was not different in Experiment 1 but was significantly poorer than controls for the 10 and 15% silage rations in Experiment 2. No apparent abnormalities of internal organs were found. (Key words: chick growth, growth depression, potatoes, potato waste) 1982 Poultry Science 61:258-261 INTRODUCTION
Large quantities of potato processing waste are used as cattle feed by feedlots located relatively close to potato processing plants. Storage of potato waste is a serious problem for feeders because of high microbial counts in the material and the high pH of the alkali peeling waste. Pit storage is considered necessary to permit fermentation to reduce pH of peeling waste: however, microbial metabolism also results in production of volatile acids which cause odor problems, toxigenic compounds which cause cattle to go off feed, and occasionally clostridial toxins which result in death losses of the cattle. In addition, microbial metabolism results in rapid breakdown of starch, as much as 15%/week (Sauter et al. 1979) with much of the loss going off as C 0 2 . Ensiling would be a simple method of storage which could prevent much of the nutrient loss if hay or straw were used to absorb the excess moisture from potato waste. A lactic acid fermentation would then develop enough acid to preserve the silage and possibly
'Published with the approval of the Director of the Idaho Agricultural Experiment Station as Research Paper No. 8142.
improve digestibility of the straw for ruminants (Klopfenstein et al, 1972). While recent literature lacks references to silage feeding of poultry, literature prior to 1950 contains frequent reference to the use of silage and other "green" feed for poultry (Buckner et al, 1943; Heuser, 1946; Ewing, 1947). Taylor et al (1944) reported silage from grass clippings did not furnish adequate riboflavin for normal chick growth and was not eaten in sufficient quantities to be an important source of protein, carotene, and possibly other factors for young chicks. Most of the early references indicate small benefits from silage feeding. The primary objective of these studies was to use chicks as a model for determining whether toxic metabolites were produced when potato waste was ensiled with alfalfa hay or barley straw as an absorbant to take up excess moisture. EXPERIMENTAL PROCEDURE
A mixture of two types of potato processing waste was used to make silage. "Dry peel" (DP), which was the highly alkaline (pH 12.5 to 14.0) residue from various modifications of the dry caustic peeling process reported by Graham et al (1968), and " filter cake" (FC), a slurry of fine particles of potato pulp that was pumped from the bottom clarifier or settling tanks. A
258
259
POTATO WASTE SILAGES FOR CHICKS TABLE 1. Composition of basal diet Ingredient
(%)
Ground yellow corn Soybean meal (45%) Menhaden fishmeal (55%) Ground limestone Dicalcium phosphate Salt, TMI1 Vitamin premix 2
55.5 35.5 5.0 1.0 2.0 .5 .5
1 Trace mineralized salt as follows: NaCl 96.9 to 99.2%, Mn .25, Fe .16, Cu .033, Co .01, I .007, Zn .005, and P .038. 2 Supplied following per kilogram of diet: 6600 IU vitamin A; 2200 ICU vitamin D 3 ; 3.3 IU vitamin E; 750 ng vitamin K; 11 jug vitamin B 1 2 ; 4.4 mg riboflavin; 27.5 mg niacin; 6.1 mg pantothenic acid; 330 mg choline; and 1 g methionine.
vacuum filter was used t o remove part of the water from filter cake. Silage for E x p e r i m e n t 1 was c o m p o s e d ofequal parts of DP and FC (v/v) mixed with c h o p p e d alfalfa hay calculated at 15% of the total p o t a t o waste used ( w e t basis). Silage for E x p e r i m e n t 2 was similar e x c e p t t h a t chopped barley straw was substituted for alfalfa hay. After mixing, the silage was packed into t w o liter Erlenmeyer flasks which were flushed with C 0 2 and sealed with plastic to maintain anaerobic conditions. F o u r replicates of four flasks/replicate were used in each experiment. T h e silage was allowed to ferment for 8 weeks a t 22 C and then analyzed for lactic acid c o n t e n t . Proximate analysis ( A O A C , 1975) and in vitro dry m a t t e r digestibility (Barnes et ai, 1971) were also d e t e r m i n e d a t this time. Silage was then dried to a c o n s t a n t weight a t 6 0 C, g r o u n d , and mixed i n t o a corn-soybean meal
(SBM) basal chick starter at levels of 5, 10, or 15% of t h e ration. T h e basal ration is shown in Table 1. Vegetable oil was added t o t h e rations containing silage t o keep all diets isocaloric with the basal. Corn and SBM were also varied t o maintain isonitrogenous rations. Day-old broiler chicks ( H u b b a r d ) were feather sexed, placed in electrically heated b a t t e r y brooders, and fed the corn-SBM basal ration for 5 days. T h e chicks were t h e n sorted by weight and experimental groups equalized to within approximately 1 g/chick. Experimental chicks were fed one of t h e following rations: basal chick starter; basal plus 5% silage; basal plus 10% silage; or basal plus 15% silage. E x p e r i m e n t 1 consisted of 3 2 0 chicks, 160 of each sex with four replicates of 10 chicks/ sex/diet. E x p e r i m e n t 2 was similar e x c e p t t h a t only three replicates were used. E x p e r i m e n t 1 was c o n t i n u e d for 3 weeks and E x p e r i m e n t 2 for only 2 weeks. Experimental chicks were group-weighed at t h e start, at weekly intervals, and at t h e termination of each e x p e r i m e n t . One-half of each group of chicks, selected at r a n d o m , was killed at the end of each exp e r i m e n t and internal organs examined for gross abnormalities. Organs from any chicks t h a t died during the experiments were also examined. Data were analyzed using t h e analysis of variance (Snedecor and Cochran, 1969) and Duncan's ( 1 9 5 5 ) multiple range test.
RESULTS AND DISCUSSION T h e average analysis of the t w o types of p o t a t o waste used and analyses of silages resulting from addition of alfalfa hay or barley straw are shown in Table 2. Dry peel was lower in dry m a t t e r , e t h e r extract, and starch b u t
TABLE 2. Analysis* of potato waste and potato waste silages Percent of dry matter Type of product
% DM
ADF
Ash
CP
Dry peel Filter cake PW + hay silage PW + straw silage
13.2 21.3 29.8 28.4
7.6 2.7 18.5 30.4
6.9 2.2 8.4 8.5
6.5 4.8 13.1 5.4
1
Average of 16 determinations per value.
EE
Starch
<1.0 2.4 4.4 4.3
50-65 60-75
Lactic acid
% In vitro DMD
8.6 5.8
60.7 90.3 65.2 64.7
SAUTER ET AL.
260
TABLE 3. Average1 microbial numbers and pH of potato waste Microorganisms/gram
Type of waste
pH
Aerobic
Ana-Fac
Dry peel Filter cake
13.2 4.9
9.2X10" 6.9X10'
3.5 X 10 s 2.1 X 10 s
1
Lactic acid
Molds 3.2 X 10 s 6.7 X 10 6
3.6X10" 6.5X10'
Average of 16 samples.
contained more fiber, ash, and crude protein than FC. In vitro digestibility of DP was also much lower than of FC, due in all probability to the highly alkaline nature of peeling waste. The silage made from potato waste and alfalfa hay was lower in fiber, contained more crude protein, and resulted in a higher lactic acid content than silage made with barley straw. Microbial numbers present in potato waste are summarized in Table 3 for various types of microorganisms. Dry peel contained significantly fewer microbes of all types than FC; however, the proportion of die total microflora represented by spore forming bacteria was much higher in DP, ranging from 35 to 65% as compared to less than 1% in FC. All rations were calculated to contain 2860 kcal/kg ME and isonitrogenous at 23.5% crude protein. Analysis of the rations indicated a range of from 23.3 to 23.7% CP. No attempt was made to control the fiber content of the diets which increased from 8.1 to 13.3% as the silage content of the rations increased. The increased fiber content of rations containing silage was probably responsible for the trend toward lower feed efficiency in the first experiment and the significantly (P<.05) poorer feed conversion in Experiment 2. High fiber
content may also have contributed to the wet sticky droppings observed in chicks fed the 10 and 15% silage rations in the second experiment. Chick performance data are summarized in Table 4 (Experiment 1). Weight data are shown for both 19 days (2 wks on experiment plus 5 days pre-experiment) and 26 days (3 wks on experiment plus 5 days pre-experiment) for comparison with Experiment 2 which was terminated after 2 weeks on experiment. Data for Experiment 2 are shown in Table 5. Chick growth rate for the silage rations was less than that of the control groups during both experiments. After feeding the experimental rations for two weeks, weights of all silage fed groups were significantly (P<.05) less than control groups fed the basal ration in Experiment 1. Chick growth during Experiment 2 was similar after 2 weeks when the study was terminated. After 3 weeks in the first experiment, only chicks fed the 10% silage rations weighed significantly (P<.05) less than the controls. There were no significant differences in feed conversion after 3 weeks during Experiment 1; however, during Experiment 2 there was a gradual increase in the feed/gain ratio as the level of silage in the ration in-
TABLE 4. Chick performance data, Experiment 19 day weight (g)
1'
26 days weight (g)
Diet
Males
Females
Avg
Males
Females
Avg
Feed/gain ratio
Basal 5% Silage 10% Silage 15% Silage
376 a 326 b 310 b 340 b
338a 299 b 292 b 300 b
357 a 312 b 301b 320 b
582 a 550ab 537 b 553ab
546 a 507 a b 493b 513 a b
564 a 529ab 515b 53 3 a b
1.69 a 1.70a 1.74a 1.73a
ab ' Values in any column having different supercripts are significantly different (P<.05). 1
Average of 4 replicates.
POTATO WASTE SILAGES FOR CHICKS
261
TABLE 5. Chick performance data, Experiment 21 19 day weights (g) Diet
Males
Females
Avg
Feed/gain ratio
Basal 5% Silage 10% Silage 15% Silage
410a 362b 365b 338b
357^ 336ab 323b 300b
384a 349b 344b 319b
1.69a 1.72ab 1.79bc 1.85C
' ' Values in any column having different supercripts are significantly different (P<.05). 1
Average of 3 replicates.
creased, resulting in a significantly (P<.05) more feed/gram of gain required for the 15% silage diet. Mortality was low in both experiments, 3 chicks during Experiment 1 and 1 chick during Experiment 2, without differences among rations. In addition, visual observation revealed no apparent lesions or abnormalities of internal organs (heart, kidney, liver, lungs, spleen or G. I. tract) or any of the chicks examined. Droppings were normal for the chicks from Experiment 1 and for basal and 5% silage diet of Experiment 2. The 10% silage ration resulted in droppings being somewhat wet with some sticking to the battery floors while the 15% silage diet produced severe caking on the floor of the batteries in Experiment 2. Results indicate that incorporating potato waste silage into a chick starter ration at levels of 5, 10, or 15% significantly (P<.05) depressed chick growth during die 2 weeks of Experiment 2 and die first 2 weeks of Experiment 1. It appears that some reduction in the percent of growth depression took place during the 3rd week of Experiment 1. Results do not indicate production of toxic metabolites during ensiling since chicks would probably become less susceptible to toxic materials with age. Examination of internal organs indicated all were normal. Reduced chick growth was probably due to high fiber content of rations containing silage. Percent growth depression was less after 3 weeks (7%) than at 2 weeks (over 12%). Ensiling may be a
viable means of preventing much of the starch loss which occurs during pit storage of potato processing waste.
REFERENCES Association of Official Analytical Chemists, 1975. Official methods of analysis. 12th ed. Washington DC. Barnes, R. F., L. D. Muller, L. F. Bauman, and V. F. Colenbrander, 1971. In vitro dry matter disappearance of brown mid rib mutants of maize (Zea mays L.) J. Anim. Sci. 33:881-884. Buckner, G. D., W. M. Insko, and A. Harms, 1943. Spring bluegrass versus mature bluegrass as pasture for laying hens. Poultry Sci. 22:248-251. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1—42. Ewing, W. R., 1947. Poultry nutrition. 3rd rev. ed. South Pasadena, CA. Graham, R. P., C. C. Huxoll, M. R. Hart, M. L. Weaver, and A. I. Morgan, 1968. Dry caustic peeling of potatoes. Proc. 18m Nat. Potato Utilization Conf., Corvallis, OR. Heuser, G. F., 1946. Feeding poultry. John Wiley and Sons, Inc., New York, NY. Klopfenstein, T. J., V. E. Krause, M. J. Jones, and W. Woods, 1972. Chemical treatment of low quality roughages. J. Anim. Sci. 35:418—422. Sauter, E. A., D. D. Hinman, and A. D. Howes, 1979. Energy losses from potato processing waste during laboratory storage. J. Anim. Sci. 49: 607-612. Snedecor, G. W., and W. G. Cochran, 1969. Statistical methods. 6th ed. Iowa State University Press, Ames, IA. Taylor, M. W., W. C. Russell, and C. S. Piatt, 1944. The value of grass clippings silage for the growing chick. Poultry Sci. 23:213-216.
Large quantities of potato processing waste are used as cattle feed by feedlots located relatively close to potato processing plants. Storage of potato waste is a serious problem for feeders because of high microbial counts in the material and the high pH of the alkali peeling waste. Pit storage is considered necessary to permit fermentation to reduce pH of peeling waste: however, microbial metabolism also results in production of volatile acids which cause odor problems, toxigenic compounds which cause cattle to go off feed, and occasionally clostridial toxins which result in death losses of the cattle. In addition, microbial metabolism results in rapid breakdown of starch, as much as 15%/week (Sauter et al. 1979) with much of the loss going off as C 0 2 . Ensiling would be a simple method of storage which could prevent much of the nutrient loss if hay or straw were used to absorb the excess moisture from potato waste. A lactic acid fermentation would then develop enough acid to preserve the silage and possibly
'Published with the approval of the Director of the Idaho Agricultural Experiment Station as Research Paper No. 8142.
improve digestibility of the straw for ruminants (Klopfenstein et al, 1972). While recent literature lacks references to silage feeding of poultry, literature prior to 1950 contains frequent reference to the use of silage and other "green" feed for poultry (Buckner et al, 1943; Heuser, 1946; Ewing, 1947). Taylor et al (1944) reported silage from grass clippings did not furnish adequate riboflavin for normal chick growth and was not eaten in sufficient quantities to be an important source of protein, carotene, and possibly other factors for young chicks. Most of the early references indicate small benefits from silage feeding. The primary objective of these studies was to use chicks as a model for determining whether toxic metabolites were produced when potato waste was ensiled with alfalfa hay or barley straw as an absorbant to take up excess moisture. EXPERIMENTAL PROCEDURE
A mixture of two types of potato processing waste was used to make silage. "Dry peel" (DP), which was the highly alkaline (pH 12.5 to 14.0) residue from various modifications of the dry caustic peeling process reported by Graham et al (1968), and " filter cake" (FC), a slurry of fine particles of potato pulp that was pumped from the bottom clarifier or settling tanks. A
258
259
POTATO WASTE SILAGES FOR CHICKS TABLE 1. Composition of basal diet Ingredient
(%)
Ground yellow corn Soybean meal (45%) Menhaden fishmeal (55%) Ground limestone Dicalcium phosphate Salt, TMI1 Vitamin premix 2
55.5 35.5 5.0 1.0 2.0 .5 .5
1 Trace mineralized salt as follows: NaCl 96.9 to 99.2%, Mn .25, Fe .16, Cu .033, Co .01, I .007, Zn .005, and P .038. 2 Supplied following per kilogram of diet: 6600 IU vitamin A; 2200 ICU vitamin D 3 ; 3.3 IU vitamin E; 750 ng vitamin K; 11 jug vitamin B 1 2 ; 4.4 mg riboflavin; 27.5 mg niacin; 6.1 mg pantothenic acid; 330 mg choline; and 1 g methionine.
vacuum filter was used t o remove part of the water from filter cake. Silage for E x p e r i m e n t 1 was c o m p o s e d ofequal parts of DP and FC (v/v) mixed with c h o p p e d alfalfa hay calculated at 15% of the total p o t a t o waste used ( w e t basis). Silage for E x p e r i m e n t 2 was similar e x c e p t t h a t chopped barley straw was substituted for alfalfa hay. After mixing, the silage was packed into t w o liter Erlenmeyer flasks which were flushed with C 0 2 and sealed with plastic to maintain anaerobic conditions. F o u r replicates of four flasks/replicate were used in each experiment. T h e silage was allowed to ferment for 8 weeks a t 22 C and then analyzed for lactic acid c o n t e n t . Proximate analysis ( A O A C , 1975) and in vitro dry m a t t e r digestibility (Barnes et ai, 1971) were also d e t e r m i n e d a t this time. Silage was then dried to a c o n s t a n t weight a t 6 0 C, g r o u n d , and mixed i n t o a corn-soybean meal
(SBM) basal chick starter at levels of 5, 10, or 15% of t h e ration. T h e basal ration is shown in Table 1. Vegetable oil was added t o t h e rations containing silage t o keep all diets isocaloric with the basal. Corn and SBM were also varied t o maintain isonitrogenous rations. Day-old broiler chicks ( H u b b a r d ) were feather sexed, placed in electrically heated b a t t e r y brooders, and fed the corn-SBM basal ration for 5 days. T h e chicks were t h e n sorted by weight and experimental groups equalized to within approximately 1 g/chick. Experimental chicks were fed one of t h e following rations: basal chick starter; basal plus 5% silage; basal plus 10% silage; or basal plus 15% silage. E x p e r i m e n t 1 consisted of 3 2 0 chicks, 160 of each sex with four replicates of 10 chicks/ sex/diet. E x p e r i m e n t 2 was similar e x c e p t t h a t only three replicates were used. E x p e r i m e n t 1 was c o n t i n u e d for 3 weeks and E x p e r i m e n t 2 for only 2 weeks. Experimental chicks were group-weighed at t h e start, at weekly intervals, and at t h e termination of each e x p e r i m e n t . One-half of each group of chicks, selected at r a n d o m , was killed at the end of each exp e r i m e n t and internal organs examined for gross abnormalities. Organs from any chicks t h a t died during the experiments were also examined. Data were analyzed using t h e analysis of variance (Snedecor and Cochran, 1969) and Duncan's ( 1 9 5 5 ) multiple range test.
RESULTS AND DISCUSSION T h e average analysis of the t w o types of p o t a t o waste used and analyses of silages resulting from addition of alfalfa hay or barley straw are shown in Table 2. Dry peel was lower in dry m a t t e r , e t h e r extract, and starch b u t
TABLE 2. Analysis* of potato waste and potato waste silages Percent of dry matter Type of product
% DM
ADF
Ash
CP
Dry peel Filter cake PW + hay silage PW + straw silage
13.2 21.3 29.8 28.4
7.6 2.7 18.5 30.4
6.9 2.2 8.4 8.5
6.5 4.8 13.1 5.4
1
Average of 16 determinations per value.
EE
Starch
<1.0 2.4 4.4 4.3
50-65 60-75
Lactic acid
% In vitro DMD
8.6 5.8
60.7 90.3 65.2 64.7
SAUTER ET AL.
260
TABLE 3. Average1 microbial numbers and pH of potato waste Microorganisms/gram
Type of waste
pH
Aerobic
Ana-Fac
Dry peel Filter cake
13.2 4.9
9.2X10" 6.9X10'
3.5 X 10 s 2.1 X 10 s
1
Lactic acid
Molds 3.2 X 10 s 6.7 X 10 6
3.6X10" 6.5X10'
Average of 16 samples.
contained more fiber, ash, and crude protein than FC. In vitro digestibility of DP was also much lower than of FC, due in all probability to the highly alkaline nature of peeling waste. The silage made from potato waste and alfalfa hay was lower in fiber, contained more crude protein, and resulted in a higher lactic acid content than silage made with barley straw. Microbial numbers present in potato waste are summarized in Table 3 for various types of microorganisms. Dry peel contained significantly fewer microbes of all types than FC; however, the proportion of die total microflora represented by spore forming bacteria was much higher in DP, ranging from 35 to 65% as compared to less than 1% in FC. All rations were calculated to contain 2860 kcal/kg ME and isonitrogenous at 23.5% crude protein. Analysis of the rations indicated a range of from 23.3 to 23.7% CP. No attempt was made to control the fiber content of the diets which increased from 8.1 to 13.3% as the silage content of the rations increased. The increased fiber content of rations containing silage was probably responsible for the trend toward lower feed efficiency in the first experiment and the significantly (P<.05) poorer feed conversion in Experiment 2. High fiber
content may also have contributed to the wet sticky droppings observed in chicks fed the 10 and 15% silage rations in the second experiment. Chick performance data are summarized in Table 4 (Experiment 1). Weight data are shown for both 19 days (2 wks on experiment plus 5 days pre-experiment) and 26 days (3 wks on experiment plus 5 days pre-experiment) for comparison with Experiment 2 which was terminated after 2 weeks on experiment. Data for Experiment 2 are shown in Table 5. Chick growth rate for the silage rations was less than that of the control groups during both experiments. After feeding the experimental rations for two weeks, weights of all silage fed groups were significantly (P<.05) less than control groups fed the basal ration in Experiment 1. Chick growth during Experiment 2 was similar after 2 weeks when the study was terminated. After 3 weeks in the first experiment, only chicks fed the 10% silage rations weighed significantly (P<.05) less than the controls. There were no significant differences in feed conversion after 3 weeks during Experiment 1; however, during Experiment 2 there was a gradual increase in the feed/gain ratio as the level of silage in the ration in-
TABLE 4. Chick performance data, Experiment 19 day weight (g)
1'
26 days weight (g)
Diet
Males
Females
Avg
Males
Females
Avg
Feed/gain ratio
Basal 5% Silage 10% Silage 15% Silage
376 a 326 b 310 b 340 b
338a 299 b 292 b 300 b
357 a 312 b 301b 320 b
582 a 550ab 537 b 553ab
546 a 507 a b 493b 513 a b
564 a 529ab 515b 53 3 a b
1.69 a 1.70a 1.74a 1.73a
ab ' Values in any column having different supercripts are significantly different (P<.05). 1
Average of 4 replicates.
POTATO WASTE SILAGES FOR CHICKS
261
TABLE 5. Chick performance data, Experiment 21 19 day weights (g) Diet
Males
Females
Avg
Feed/gain ratio
Basal 5% Silage 10% Silage 15% Silage
410a 362b 365b 338b
357^ 336ab 323b 300b
384a 349b 344b 319b
1.69a 1.72ab 1.79bc 1.85C
' ' Values in any column having different supercripts are significantly different (P<.05). 1
Average of 3 replicates.
creased, resulting in a significantly (P<.05) more feed/gram of gain required for the 15% silage diet. Mortality was low in both experiments, 3 chicks during Experiment 1 and 1 chick during Experiment 2, without differences among rations. In addition, visual observation revealed no apparent lesions or abnormalities of internal organs (heart, kidney, liver, lungs, spleen or G. I. tract) or any of the chicks examined. Droppings were normal for the chicks from Experiment 1 and for basal and 5% silage diet of Experiment 2. The 10% silage ration resulted in droppings being somewhat wet with some sticking to the battery floors while the 15% silage diet produced severe caking on the floor of the batteries in Experiment 2. Results indicate that incorporating potato waste silage into a chick starter ration at levels of 5, 10, or 15% significantly (P<.05) depressed chick growth during die 2 weeks of Experiment 2 and die first 2 weeks of Experiment 1. It appears that some reduction in the percent of growth depression took place during the 3rd week of Experiment 1. Results do not indicate production of toxic metabolites during ensiling since chicks would probably become less susceptible to toxic materials with age. Examination of internal organs indicated all were normal. Reduced chick growth was probably due to high fiber content of rations containing silage. Percent growth depression was less after 3 weeks (7%) than at 2 weeks (over 12%). Ensiling may be a
viable means of preventing much of the starch loss which occurs during pit storage of potato processing waste.
REFERENCES Association of Official Analytical Chemists, 1975. Official methods of analysis. 12th ed. Washington DC. Barnes, R. F., L. D. Muller, L. F. Bauman, and V. F. Colenbrander, 1971. In vitro dry matter disappearance of brown mid rib mutants of maize (Zea mays L.) J. Anim. Sci. 33:881-884. Buckner, G. D., W. M. Insko, and A. Harms, 1943. Spring bluegrass versus mature bluegrass as pasture for laying hens. Poultry Sci. 22:248-251. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1—42. Ewing, W. R., 1947. Poultry nutrition. 3rd rev. ed. South Pasadena, CA. Graham, R. P., C. C. Huxoll, M. R. Hart, M. L. Weaver, and A. I. Morgan, 1968. Dry caustic peeling of potatoes. Proc. 18m Nat. Potato Utilization Conf., Corvallis, OR. Heuser, G. F., 1946. Feeding poultry. John Wiley and Sons, Inc., New York, NY. Klopfenstein, T. J., V. E. Krause, M. J. Jones, and W. Woods, 1972. Chemical treatment of low quality roughages. J. Anim. Sci. 35:418—422. Sauter, E. A., D. D. Hinman, and A. D. Howes, 1979. Energy losses from potato processing waste during laboratory storage. J. Anim. Sci. 49: 607-612. Snedecor, G. W., and W. G. Cochran, 1969. Statistical methods. 6th ed. Iowa State University Press, Ames, IA. Taylor, M. W., W. C. Russell, and C. S. Piatt, 1944. The value of grass clippings silage for the growing chick. Poultry Sci. 23:213-216.