Influence of Dietary Levels of Fat, Fiber, and Copper Sulfate and Fat Rancidity on Cecal Activity in the Growing Turkey

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1 Influence of Dietary Levels of Fat, Fiber, and Copper Sulfate and Fat Rancidity on Cecal Activity in the Growing Turkey S. LEESON,* A. K. ZUBAIR,* E. J. SQUIRES,* and C. FORSBERG *Department of Animal and Poultry Science and Department of Microbiology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1 ABSTRACT Two experiments were conducted with 6- to 10-wk-old turkeys. In Experiment 1, 6-wk-old turkeys were fed diets varying in level of fat (4.4 to 10%) or fiber (2.5 to 9.0%). The diets also contained extra copper as copper sulfate at either 0.1 or 0.2% of the diet. At 8 wk of age, 15 replicate birds were housed in individual cages and all excreta was collected. Excreta was separated as being regular or cecal in origin based on appearance. At 10 wk of age, 10 birds per treatment were killed and cecal contents removed under anaerobic conditions. Cecal contents were assayed for various nutrients and viscosity was measured. In a second comparable study, turkeys were fed animalvegetable fat or regular or rancid canola oil (60.25 vs ng/g malonaldehyde, respectively). In Experiment 1, feeding copper sulfate had the most noticeable effect on various cecal parameters. There was an increase (P < 0.01) in dry matter cecal droppings produced and the cecal contents were of increased Received for publication April 29, Accepted for publication August 30, British United Turkeys of America, Lewisburg, WV viscosity (P < 0.05). Copper had no effect on ph or microbial colony count of the cecal contents. Feeding copper resulted in a significant increase in the high molecular weight (> 300,000) fraction of cecal contents and this fraction was of higher viscosity. Feeding copper sulfate resulted in a dramatic increase in copper content of cecal contents (280 to 11,848 ppm), although the copper content of regular excreta was also increased (17 to 1,008 ppm). The various levels of fiber and fat generally had no effect on cecal parameters. Feeding rancid canola oil did result in increased viscosity of cecal contents, compared to the situation seen with fresh canola oil. Fat rancidity per se, however, failed to influence other parameters such as total mass of cecal material produced and composition of cecal material. Feeding copper sulfate or rancid fat will increase the viscosity of cecal material, which may contribute to litter management problems. (Key words: turkey, ceca, copper, excreta viscosity, fat rancidity) INTRODUCTION In a previous publication (Zubair et al., 1996), we described a problem of unusually high excretion of viscous cecal droppings in 8- to 10-wk-old turkeys. The unusual production of this viscous material causes caked-damp litter that can lead to leg and foot pad problems and promote breast blemishes. Although the functions of the ceca relate to water resorption (McNab, 1973) and degradation of fiber components (Gasaway, 1976), we have recently shown little effect of fiber per se on output and composition of cecal material from growing turkeys (Zubair et al., 1996). In the current study, we have focused on the potential roles of dietary copper and the use of regular vs rancid fat. Copper is often added to turkey diets in order to promote growth (Harms and Buresh, 1987), and 1997 Poultry Science 76:59 66 although such practice is known to influence color of the excreta, there are no reports of copper influencing cecal activity. At around 8 to 10 wk of age, it is common practice to start increasing the fat content of the turkey grower diets as a means of increasing diet energy level. Oxidative fat rancidity is known to influence fat digestibility (Wiseman, 1986), although again there is no information available on any role such undigested fat may have on cecal activity in turkeys. Two trials were designed to study the roles of dietary copper and rancid fat on cecal activity in growing turkeys. Experiment 1 MATERIALS AND METHODS This experiment was conducted to determine the effects of dietary fat, fiber, and copper sulfate on cecal activity in turkeys. Five treatments were involved, each comprising of 25 BUTA1-SIX turkey poults. During the starter period, 0 to 6 wk of age, all birds received a 59

2 60 LEESON ET AL. TABLE 1. Percentage diet composition Ingredients Starter Diet 1 Diet 2 Diet 3 Diet 4 Diet 5 (%) Corn Soybean meal (48% CP) Wheat Wheat bran Meat meal Fish meal Feather meal Alphafloc Animal-vegetable fat Limestone Calcium phosphate (20% P) Dicalcium phosphate Iodized salt Vitamin-mineral premix DL-methionine L-lysine Coban (monensin) CuSO Calculated nutrient content CP ME, kcal/kg 2,886 3,009 2,996 3,009 3,000 3,000 Crude fat Crude fiber Calcium Available P Methionine + cystine Lysine Replaced by the same amount of fresh and rancid canola oils in Treatments 2 and 3 of Experiment 2, respectively. Malondialdehyde assay levels: AV fat, ng/g; fresh canola, ng/g, rancid canola, ng/g. 2Supplied per kilogram of diet: vitamin A, 8,000 IU; cholecalciferol, 1,600 IU; vitamin E, 11.0 mg; riboflavin, 9.0 mg; pantothenic, 11.0 mg; vitamin B 12,13mg; niacin, 26 mg; choline, 900 mg; vitamin K, 1.5 mg; folic, 1.5 mg; biotin, 0.25 mg; antioxidant, 125 mg; manganese, 55 mg; zinc, 50 mg; copper, 5 mg; iron, 30 mg; and selenium, 0.1 mg. conventional turkey starter diet (Table 1). From 6 to 10 wk of age, turkeys in Treatments 1 to 5 received Diets 1 through 5, respectively. Diet 1 for the control group was formulated to contain 4.87% crude fat, 2.56% crude fiber, and no copper sulfate (Table 1). Diets 2 and 3 differed from Diet 1 in their crude fat and crude fiber contents. Diets 4 and 5 on the other hand, contained 0.1 and 0.2% copper sulfate respectively, whereas the control diet (Diet 1) contained no supplemental copper other than the copper sulfate present in the mineral premix (Table 1). Up to 8 wk of age turkeys were grown in conventional litter floor pens with standard management practices. At 8 wk of age, 15 birds from each treatment were transferred into individual cages measuring 50 cm 70 cm 50 cm high, with the locations of cages randomized among the treatment groups. An aluminum tray was provided underneath each cage for the daily collection of the excreta. From 9 to 10 wk of age, the excreta from each bird were collected twice daily, identified as either regular or of cecal origin, separated, and weighed. Daily records of weight and frequency of cecal droppings per bird were kept during this period. Samples collected during the last 4 d of the experiment were freeze-dried and used for chemical analysis. Daily feed intake per bird during the 2Horiba Instruments, Inc., Irvine, CA wk period in cages (8 to 10 wk of age) was also recorded. All birds were weighed individually at 6, 8, and 10 wk of age. At 10 wk of age, 10 birds were randomly selected from each treatment and killed by cervical dislocation for collection of cecal contents. The two ceca were carefully removed at the ileo-cecal-colonic junction. About 0.5 g of cecal contents were taken from the blind end of each ceca and used to measure ph, by means of a Twin Compact Digital ph meter.2 The open ends of each cecum were sealed with aseptic tape. One cecum from each turkey was placed in a test tube measuring 20 cm 2.5 cm. In order to maintain anaerobic conditions in the ceca, a steady stream of nitrogen was passed into the test tube for about 30 s at 10 psi to flush out oxygen. The tube was then quickly covered with a rubber stopper and kept on ice prior to microbial analysis. The second ceca of each turkey were kept on ice for up to 2 h until required for measurement of viscosity and chemical analysis. Measurement of Viscosity and Chemical Composition Two grams of each sample of cecal contents were centrifuged for 10 min at 4 C and 15,000 g. The supernatant was withdrawn and stored on ice until

3 CECAL ACTIVITY IN TURKEYS 61 required for measurement of viscosity. One milliliter of the supernatant was used to measure the viscosity, using a Brookfield Synchro-Lectric Viscometer,3 at a shear rate of 45 1 and at 40 C, as described by Bedford and Classen (1993). Samples of the cecal content were also processed for determination of volatile fatty s. The remaining samples of the cecal contents, and the cecal and regular droppings were freeze-dried4 to constant weight, and then ground using a Commercial Waring Blender5 to give homogenous consistency. All ground samples were assayed for dry matter, total nitrogen, crude fat, crude fiber, and copper by the methods outlined by the Association of Official Analytical Chemists (1984). Determination of Microbial Count of Cecal Contents Strict anaerobic conditions were maintained throughout all procedures involving dilution of cecal samples, inoculation to the media plates, and incubation inside an oxygen-free chamber.6 Anaerobic techniques used were as described by Salanitro et al. (1974) for chicken cecum involving, briefly, the following procedures. Contents of the ceca were squeezed into a plastic measuring dish. About 1 g of each sample was weighed and processed through serial 10-fold dilutions in tubes of M98-5 anaerobic media, initially used for chicken ceca by Salanitro et al. (1974) and later for turkey ceca (Bedbury and Duke, 1983). Composition and preparation of M98-5 medium are described in detail by Salanitro et al. (1974). Ten microliters of three dilutions (10 8, 10 9, and 10 10) of the medium were each added to culture plates. All plates were incubated for 48 h at 37 C in an anaerobic incubator.6 Determination of colony counts was done in triplicate from plates that were inoculated with 10 8, 10 9n, and diluted cecal contents. Total colony counts per gram of undiluted cecal content were calculated for each dilution level and these were used to calculate the mean count per gram of cecal contents and total count per bird. Determination of Molecular Weight Distribution of Cecal Content Three grams of each cecal sample were centrifuged for 10 min at 4 C and 15,000 g. The supernatant was withdrawn and filtered through Diaflo ultrafilters.7 Four different filter sizes were used to represent separation at four MW distributions, viz., > 300,000, 100,000 to 300,000, 30,000 to 1000, and < 30,000. Each filter was dried for 10 min and weighed before use. After filtration, each filter 3Brookfield Engineering Laboratories, Stroughton, MA The Virtis Co., Gardiner, NY Waring Products Division, New Hartford, CT Forma Scientific Anaerobic System, Model 1024, Marietta, OH Diaflo Ultrafilters, Amicon, MA was dried at 60 C to constant weight and then weighed again to determine the amount of substance retained. Experiment 2 The objective of Experiment 2 was to test the effect of quality of dietary fat on cecal activity in turkeys. Three treatments were involved, differing either in type or rancidity of dietary fat. All experimental procedures, including feeding from 0 to 6 wk, were as described for Experiment 1. From 6 to 10 wk, turkeys in the control group received Diet 3, which contained an animalvegetable blend fat (Table 1). This fat was replaced by either fresh canola oil or rancid canola oil (Treatments 2 and 3, respectively). The fresh canola oil used in Treatment 2 was obtained fresh from the processing plant, with no anti-oxidant added, and stored under refrigeration for 60 d until required for the diet mixing. The rancid canola oil used in the diet for turkeys in Treatment 3 was obtained from the same source but stored at room temperature (21 C) for 60 d before diet mixing. As a measure of rancidity, malondialdehyde levels of the different fats and the respective diets were determined by thiobarbituric test. Details of the procedure are described by Squires et al. (1991). The malondialdehyde value for the fat stored at room temperature for 60 d is significantly elevated, and values are consistent with oxidative rancidity. All other operations from 6 to 10 wk were carried out as described for Experiment 1, except that there was no analysis for copper content. Statistical Analysis All data were subjected to one-way analysis of variance (SAS Institute, 1991). Those variables having a significant F test were compared using Duncan s multiple range test (Duncan, 1955). Contrasts of treatments were also carried out to determine the specific effects of different dietary factors. Logarithm of copper levels in the cecal contents and the concentrations of the highest molecular weight fractions (HMW) retained on the filter > 300,000 were each subjected to correlation with the viscosity. Experiment 1 RESULTS Diet treatments had no effect on growth and development of the turkey to 10 wk of age and, in general, body weight and feed efficiency were comparable to commercial expectations (Table 2). There was no significant (P > 0.05) difference in the total number of cecal evacuations per bird; however, birds fed the two levels of supplemental copper sulfate produced more cecal dry matter material than did birds fed either the control diet or the

4 62 LEESON ET AL. TABLE 2. Effect of dietary fat, fiber, and CuSO 4 on growth performance of male BUTA turkeys, Experiment 1 Body weight Body weight gain Feed efficiency Treatment CuSO 4 Fat Fiber 6 wk 8 wk 10 wk 6 to 8 wk 6 to 10 wk 6 to 10 wk (%) (g/bird) (g:g) ,690 4,492 6,398 1,802 3, ab ,775 4,553 6,385 1,778 3, a ,454 6,365 1,801 3, ab ,711 4,642 6,529 1,931 3, bc ,613 4,458 6,419 1,845 3, c SD Probability Contrast of treatments 1 vs 2 & 3 NS NS NS NS NS NS 2 vs 1 & 3 NS NS NS NS NS NS 1 vs 4 & 5 NS NS NS NS NS NS a cmeans within columns with no common superscript differ significantly (P < 0.05). Values are means for 15 observations. high fat-low fiber diet (P < 0.05, Table 3). There was no difference in cecal dry matter material relative to fat treatments (1 vs 2 and 3, Table 3). Weight of the empty ceca was not affected by diet treatment. Viscosity of cecal contents was significantly (P < 0.05) increased by inclusion of 0.1 or 0.2% copper sulfate (Table 3). Neither ph nor cecal colony count was affected by diet (Table 3). High levels of dietary copper sulfate also caused a significant (P < 0.01) increase in the contents of the ceca with molecular weight > 300,000 (Table 4). This trend continued with components in the 100 to 300,000 molecular weight range, although the effect was not statistically significant. This increase in contents with molecular weight > 300,000 caused by copper sulfate translated into increased viscosity in both the > 300,000 and the 100 to 300,000 MW components (P < 0.01, Table 4). TABLE 3. Effect of dietary fat, fiber, and CuSO 4 on cecal characteristics of male BUTA turkeys, Experiment 1 Treatment 1 CuSO 4 Fat Fiber Cecal droppings per 7 d per bird There was no difference in viscosity across treatments for the components whose molecular weight was < 100,000. Adding 10% fat, with or without high fiber, caused a reduction in fat content of cecal contents, although compositions of cecal and regular droppings were not altered (Table 5). The higher levels of dietary copper had little effect on any parameters, other than copper content, of all fractions examined. Both cecal contents and cecal droppings showed dramatic increase in copper content when copper sulfate was added to the diet (P < 0.01, Table 5). A significant (P < 0.01) but less dramatic increase in copper content of regular droppings occurred in response to feeding copper. Interestingly, even under control conditions, there was a concentration of copper in the cecal content and droppings relative to that occurring in the regular droppings (Treatment 1, Table 5). There was a Total number Dry weight Empty cecal weight Viscosity Colony count ( 10 8 ) (%) (g) (g/bird) (% BW) (mpa) (ph) (per g cecal content) b b ab b b b a ab a a SD Probability Contrast of treatments 1 vs 2 & 3 NS NS NS NS NS NS NS NS 2 vs 1 & 3 NS NS NS NS NS NS NS NS 1 vs 4 & 5 NS ** NS NS * NS NS NS (Total per bird) a bmeans within columns with no common superscript differ significantly (P 0.05). Values are means of 10 observations.

5 CECAL ACTIVITY IN TURKEYS 63 TABLE 4. Effect of dietary fat, fiber, and CuSO 4 on molecular weight distribution and viscosity of cecal contents of male BUTA turkeys, Experiment 1 Molecular weight fraction Viscosity 100,000 to 30,000 to 100,000 to 30,000 to Treatment CuSO 4 Fat Fiber >300, , ,000 >300, , ,000 <30,000 (%) (g/l cecal content) (mpa) c 4.85 b b 1.84 c c 5.41 ab b 1.83 c bc 2.56 b b 1.89 c b 9.41 a ab 2.39 b a 5.74 ab a 3.05 a SD Probability Contrast of treatments 1 vs 2 & 3 NS NS NS NS NS NS NS 2 vs 1 & 3 NS NS NS NS NS NS NS 1 vs 4 & 5 ** * NS ** ** NS NS a cmeans within columns with no common superscript differ significantly (P 0.05). highly significant correlation between cecal copper content and viscosity of the cecal contents (Figure 1) and between such viscosity and the concentration of very high molecular weight compounds of the cecal contents (Figure 2). Diet treatment had no effect on volatile fatty s found in cecal contents (P > 0.05, Table 6). Experiment 2 Fat sources had no effect on growth rate and feed efficiency, and these values appeared within normal ranges for this age of turkey (Table 7). Feeding canola oil, regardless of degree of rancidity, caused an increase in the number of cecal evacuations per bird over a given time (Table 8), although dry matter excretion was unaffected. Empty cecal weight was not affected by diet oil inclusion, although feeding rancid canola oil caused an increase in viscosity of the cecal contents (P > 0.05; Table 8). Adding canola oil, rather than an animal-vegetable blend fat, to the diet caused an increase in the proportion of fat in cecal contents and cecal droppings (Table 9). However, in regular droppings, the converse is seen with significantly less fat for birds fed fresh canola oil vs animal-vegetable fat (Table 4). Diet had no effect on any of the other cecal or regular droppings constituents. DISCUSSION Copper is often added to turkey diets in order to stimulate growth (Harms and Buresh, 1987) although there are indications that copper may also have some antibiotic properties (King, 1975a), acting in some way to reduce bacterial toxin production. These conclusions infer some change in bacterial population of the gastrointestinal tract. In the present study, copper resulted in a nonsignificant increase in growth rate, although at the highest inclusion level of 0.2% CuSO 4, there was significant improvement in feed efficiency, relative to birds fed only copper in the trace mineral mix. The addition of copper sulfate increased by almost 50% the dry weight of cecal droppings, and although FIGURE 1. Correlation between concentration of copper and viscosity of cecal contents, Experiment 1. FIGURE 2. Correlation between concentration (conc.) of high molecular weight (HMW) compounds and viscosity of cecal contents, Experiment 1.

6 64 LEESON ET AL. TABLE 5. Effect of dietary fiber, fat, and CuSO 4 on composition of cecal content, cecal droppings, and regular droppings of male BUTA turkeys Cecal content Cecal droppings Regular droppings Treatment CuSO 4 Fat Fiber DM Fat Fiber N Cu 2 Fat Fiber N Cu 2 DM1 Fat Fiber N Cu 2 (%) (% DM) a 0.61 ab 9.07 a 280 c 3.90 b 3.20 b c ab 8.86 c 6.50 a 17 c ab 0.56 ab 8.70 ab 176 c 4.23 ab 5.40 a c a a 5.57 b 26 c bc 0.73 a 8.00 c 164 c 4.07 b 2.92 b c ab b 5.63 b 20 c abc 0.33 b 8.33 bc 5,448 b 3.77 b 5.13 a ,956 b b 9.44 c 6.53 a 413 b c 0.41 b 8.73 ab 11,848 a 4.63 a 4.77 a ,317 a b 9.71 c 6.73 a 1,008 a SD Probability Contrast of treatments 1 vs 2 & 3 NS ** NS NS NS NS NS NS NS NS NS ** ** NS 2 vs 1 & 3 NS NS NS NS NS NS ** NS NS NS NS ** NS NS 1 vs 4 & 5 NS ** NS NS ** NS ** NS ** NS NS NS NS ** a cmeans within rows within experiments with no common superscript differ significantly (P 0.05). there was no effect on total anaerobes present in the ceca, the viscosity of their contents increased quite dramatically. King (1975b), working with ducklings, indicated that supplemental copper significantly reduced the size of the ceca both as a proportion of body weight and in terms of weight per unit length. King (1975a) showed similar results in rabbits; however. with chicks (King, 1972), there was increase in relative weight of the ceca per unit body weight. The present studies carried out with turkeys fit neither of these patterns, because in the current study copper had no effect on cecal weight (Table 3). Feeding high levels of copper resulted in a significant increase in the larger molecular weight components of the cecal contents, and this was associated with increase in viscosity (Table 4). The mode of action of this increased viscosity is not clear at this time. There was reduction in fat content of cecal contents due to feeding copper, although by far the largest change in composition relates to copper content per se. The data shown in Table 5 suggests that copper is diverted into the ceca, because levels are far beyond that expected due to changes in the concentration of other nutrients, including dry matter. The copper content of the regular droppings also increased, although the concentration of copper occurring in the ceca is another order of magnitude. Interestingly, the cecal copper concentration of poults fed the basal diet without copper supplementation is also much higher than that appearing in regular droppings, and so this concentrating-diverting effect appears to occur at any level of mineral supplementation. Copper may enter the ceca directly from the digesta, or via retrograde flow from urine as occurs with nitrogenous products (Son et al., 1996). Adding 0.2% dietary copper caused a 12 increase in cecal over regular droppings copper content, vs a 16 increase seen with the unsupplemented basal diet. It is unclear, therefore, whether copper per se contributes to increased cecal content viscosity. Another possible explanation relates to the indirect effect of copper on hemicellulose digestibility. Aoyagi and Baker (1995) suggest that feeding 250 ppm copper in the diet of chickens results in a significant increase in hemicellulose digestibility. Aoyagi and Baker (1995) ascribe this activity to the Treatment CuSO 4 Fat Fiber TABLE 6. Effect of dietary fat, fiber, and copper sulfate on volatile fatty s in cecal contents of male BUTA turkeys, Experiment 1 1 Acetic Propionic Butyric Isovaleric Valeric (%) SD Significance NS NS NS NS NS NS 1Values are means of 10 observations. Total

7 CECAL ACTIVITY IN TURKEYS 65 TABLE 7. Effect of dietary fat quality on growth performance of male BUTA turkeys, Experiment 2 1 Body weight gain Feed efficiency Treatment 2 8 wk 10 wk 8 to 10 wk 8 to 10 wk (g/bird) (g:g) Animal-vegetable blend 3,679 5,634 1, Fresh canola oil 3,580 5,526 1, Rancid canola oil 3,644 5,506 1, SD Significance NS NS NS NS 1Values are means of 15 observations. 2Dietary fat at 8.0% inclusion level. stimulation by lysosomal enzymes through bile, caused by copper, and that b-glucuronidase will likely be a component of this secretion. The authors conclude that copper functions to free hemicellulose for enzymatic attack, and that microbes may play some role in this activity. It is possible that the large molecular weight fractions and their associated high viscosity, which occur in response to copper sulfate feeding (Table 4), may be components of enhanced hemicellulose degradation. Aoyagi and Baker (1995) used cecectomized birds and recorded a 37 vs 22% true hemicellulose digestibility in response to dietary copper. Changing the level of fat or fiber in the diet generally had little effect on cecal growth or composition of contents. Adding 10% dietary fat, with low fiber at 3.13%, resulted in a significant reduction in fat content of the cecal contents, whereas the composition of cecal droppings was unchanged. Zubair et al. (1996) recorded similar findings when high fat diets also contained the anticoccidial Coban. Increasing the fiber and fat content of the diet (Treatments 2, Table 5) caused an increase in the fiber content of the cecal droppings, although the fiber content of the cecal contents was unchanged. The largest change in fiber content occurred with the regular droppings, showing that the fiber source used was largely undigestible. In the second experiment, the degree of rancidity of canola oil had little effect on cecal characteristics. Canola oil per se did increase the number of cecal evacuations relative to birds fed a more saturated animal-vegetable blend fat, although the dry matter yield of these excretions was not changed. Using the rancid canola oil with malonaldehyde assay at 120 vs 60 ng/g for fresh oil (Table 1) did cause an increase in viscosity of cecal contents; however, this change in viscosity cannot be related to any compositional changes in contents of the ceca (Table 9). Because a balance study was not undertaken, it is not possible to infer data on overall fat digestibility based on fat assays of the regular droppings. Thus, although fat content of excreta was unchanged, it is still possible that the rancid fat influenced cecal content viscosity. Whereas the gut microflora may generally impair fat digestion (Jayne- Williams and Fuller, 1976) there is no information available on the effect of microbial activity in the presence of rancid fats. Data from this study, and that reported by Zubair et al. (1996), confirm that fiber per se is not a factor in cecal activity in the turkey, and does not seem to contribute to greater, or more viscous cecal contents. Bedbury and Duke (1983) did suggest that the cecal microflora of turkeys was changed in response to fiber level, although TABLE 8. Effect of dietary fat quality on cecal characteristics of male BUTA turkeys, Experiment 2 Cecal droppings Treatment 1 No. Dry weight Cecal weight Viscosity ph Colony count ( 10 8 ) (7 d per bird) (g/bird/7 d) (g/bird) (% BW) (mpa) (per g wet weight) (per bird) Animal-vegetable blend a b Fresh canola oil a b Rancid canola oil a a SD Significance ** NS NS NS * NS NS NS a bmeans within columns with no common superscript differ significantly (P 0.05). Values are means of 10 observations. 1Dietary fat at 8.0% inclusion level.

8 66 LEESON ET AL. TABLE 9. Effect of dietary fat quality on cecal characteristics of male BUTA turkeys, Experiment 2 Cecal content Cecal droppings Regular droppings Treatment 1 DM Fat N Fiber Fat N Fiber DM Fat N Fiber (% DM) Animal-vegetable fat b b a Fresh canola oil a a b Rancid canola oil a a ab SD Significance NS * NS NS ** NS NS NS * NS NS a,bmeans within columns with no common superscript differ significantly. Values are means of 10 observations. 1Dietary fat at 8.0% inclusion level. there was no indication of practical consequences of such adaptation. Adding supplemental dietary copper had the most dramatic effect on quality and consistency of cecal contents. The mode of action of copper in affecting cecal content viscosity is unknown at this time. Rolls (1977) suggests that the mode of action of antibiotics in their effect on cecal viscosity is via suppression of mucinases, which normally reduce the adverse effect of mucous products in the gut. Copper is claimed to improve growth rate through influencing the gut microflora, much as does an antibiotic, and so this may be a useful area for future research. However, in previous studies (Zubair et al., 1996), we have shown no effects on cecal activity by feeding monensin, a polyether ionophore. It is concluded that one adverse effect of feeding high levels of dietary copper is and increase in cecal evacuation of a more viscous material. ACKNOWLEDGMENTS This work was supported by British United Turkeys of America, Lewisburg, WV 24901, and the Ontario Ministry of Agriculture Food and Rural Affairs, Toronto, ON, Canada. REFERENCES Aoyagi, S., and D. H. Baker, Effect of high copper dosing on hemicellulose digestibility in cecectomized cockerels. Poultry Sci. 74: Association of Official Analytical Chemists, Official Methods of the Association of Official Analytical Chemists. 12th ed. Association of Official Analytical Chemists, Washington, DC. Bedbury, H. P., and G. E. Duke, Cecal microflora of turkeys fed low or high fiber diets. Enumeration, identification and determination of cellulytic activity. Poultry Sci. 62: Bedford, M. R., and H. L. Classen, An in vitro assay for prediction of broiler intestinal viscosity and growth when fed rye-based diets in the presence of exogenous enzymes. Poultry Sci. 72: Duncan, D. B., Multiple range and multiple F tests. Biometrics 11:1 42. Gasaway, W. C., Volatile fatty s and metabolizable energy derived from cecal fermentation in the willow ptarmigan. Comp. Biochem. Physiol. 53A: Harms, R. H., and R. E. Buresh, Influence of three levels of copper on the performance of turkey poults with diets containing two sources of methionine. Poultry Sci. 66: Jayne-Williams, D. J., and R. Fuller, The influence of the intestinal microflora on nutrition. Pages in: Physiology and Biochemistry of the Domestic Fowl. D. J. Bell and B. M. Freeman, ed. Academic Press, New York, NY. King, J.O.L., The feeding of copper sulphate to growing fowls. Br. Poult. Sci. 13: King, J.O.L., 1975a. The feeding of copper sulphate to growing rabbits. Br. Vet. J. 131: King, J.O.L., 1975b. The feeding of copper sulphate to ducklings. Br. Poult. Sci. 16: McNab, J. M., The avian ceca: a review. World s Poult. Sci. J. 29: Rolls, B. A., Inorganic ions in the intestinal and cecal contents of germ-free and conventional chickens. Lab. Anim. 11: Salanitro, J. P., I. G. Fairchilds, and Y. D. Zgornicki, Isolation, culture characteristics and identification of anaerobic bacteria from the chicken cecum. Appl. Microbiol. 27: SAS Institute, SAS for Linear Models. SAS Institute Inc., Cary, NC. Son, J. H., Y. Karasawa, and K. Koh, Comparative effect of ligation of ceca on nitrogen utilization and nitrogen excretion in chickens fed a low protein diet or a low protein diet plus urea. Anim. Sci. Technol. (Jpn.) 67: Squires, E. J., E. V. Valdes, J. Wu, and S. Leeson, Utility of the thiobarbituric test in the determination of the quality of fats and oils in feeds. Poultry Sci. 70: Wiseman, J., Antinutritional factors associated with dietary fats and oils. Pages in: Recent Advances in Animal Nutrition. W. Haresign and D.J.A. Cole, ed. Butterworths, London, UK. Zubair, A. K., C. Forsberg, and S. Leeson, Effect of dietary fat, fiber, and monensin on cecal activity in turkeys. Poultry Sci. 75: