INFLUENCE OF FEED PREPARATION AND NUMBER OF PIGS PER PEN ON PERFORMANCE AND OCCURRENCE OF ESOPHAGOGASTRIC ULCERS IN SWINE 1

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1 I INFLUENCE OF FEED PREPARATION AND NUMBER OF PIGS PER PEN ON PERFORMANCE AND OCCURRENCE OF ESOPHAGOGASTRIC ULCERS IN SWINE 1 R. A. PICKETT, 2 W. H. FUGATE, a R. B. HARRINGTON, T. W. PERRY AND T. M. CURTIN 4 Purdue University, Lafayette, Indiana NVESTIGATORS at this station have reported an increased incidence of esophago- gastric ulcers in pigs fed diets containing finely ground feeds and in those fed expanded grains (Mahan et al., 1966; Perry et al., 1963; Riker et al., 1967a, b). Chamberlain, Merriman and LidvalI (1964) and Pocock, Bayley and Roe (1968) reported that pelleting of the diet increased the incidence of such lesions in swine. On the other hand, Becker, Jensen and Harmon (1964) reported that pelleting of swine diets increased efficiency of feed conversion, especially when the ration ingredients were finely ground. Nuwer et al. (1965) found no protective effect against esophagogastric lesions in swine by the incorporation of a number of additives and nutrients including oxytetracycline, higher levels of vitamin A, tocopherol, an amylolyticproteolytic enzyme, librium hydrochloride or an antihistamine into the diet. However, both Maxson et al. (1968) and Maxwell et al. (1966) were able to afford protection against such lesions by including of 2.5~ oat hulls in the diet. The objective of the research reported in this paper was to continue the study of causative factors of esophagogastric lesions in swine including (1) varying degrees of ration particle size, (2) pelleting, (3) regrinding of pelleted diets, (4) floor space per pig and (5) sex. Experimental Procedure Experiment I. Two-hundred-ten Hampshire x Yorkshire (H x Y) pigs averaging 21.9 kg. were allotted to seven treatments (one pen of 10 and one pen of 20 pigs each) on the basis of sex, weight and litter. Diets, the composi- x Department of Animal Sciences Journal Paper No. 3494, Purdue University Agricultural Experiment Station. A portion of this research was supported by Grant No. AM of the National Institutes of Health, U. S. Dept. of Health Education, and Welfare. Deceased. z Present address: Falrbury, Illinois. Department of Veterinary Science. Present address: University of Missouri. tion of which is shown in table 1, were based on ( 1 ) expanded corn; (2) finely ground corn (0.16 cm. hammermill screen); (3) medium ground corn (1.27 cm. hammermill screen); (4) coarsely ground corn (2.54 cm. hammermill screen); (5) medium rolled corn (particle size similar to treatment 3); (6) coarsely rolled corn (particle size similar to treatment 4) and (7) shelled corn and supplement (table 1) free-choice. Expanded corn was prepared by processing through a Wenger grain expander as described by Nuwer et al. (1965). The moduli of fineness and uniformity were determined for each ration in the manner described by Henderson and Perry (1955). The modulus of fineness is expressed as one number and is an indication of the relative fineness or coarseness of a feed sample. These values range from 0 to 7 with the lower number indicating a fine particle size and the higher number denoting a coarser particle size. The modulus of uniformity is expressed as a ratio of three figures (the total is always equal to 10) which indicate the proportionate amounts of coarse, medium and fine particles, respectively. Moduli of uniformity and of fineness, respectively, were: expanded corn, 0:4:6 and 2.03; finely ground corn, 0:3:7 and 2.37; medium ground corn, 1 : 6:3 and 3.66; coarsely ground corn, 4:4:2 and 3.90; shelled corn 10:0:0 and 6.0; supplement, 0: 7: 3 and Concrete floored feeding lots provided 11 m3 of outside pen space and 1.1 m3 of house space per pig for the 10 pig groups and onehalf that amount of space for the 20 pig groups. Feed and water were supplied ad libiturn with the same amount of feeder space available per pig in each pen. This experiment was conducted during the summer. Pigs were removed from the feeding pens at weekly intervals as their weights exceeded 91 kg. and were slaughtered following approximately 24 hr. of fast. Their stomachs were examined and classified as normal, cornified, eroded or ulcerated according to the condition of the stratified squamous epithelial area of 837

2 838 PICKETT ET AL. the esophageal portion (Curtin, Goetsch and Hollandbeck, 1963). Multiple regression analysis (Steel and Torrie, 1960) was used to determine significant effects of the independent variables of sex, number of pigs per pen and modulus of fineness of feed on the average daily gains and on the incidence of esophagogastric lesions. Stomach index scoring used was 10~normal stomach; 8=cornification only; 5~erosions; 2-~ esophagogastric ulcers; 0=death due to ulcers. Experiment H. This experiment was conducted during the winter in the same manner as experiment 1 using 210 H x Y pigs averaging 24 kilograms. All pigs received complete mixed diets based on (1) expanded corn; (2) finely ground corn (0.16 cm. hammermill screen) ; (3) diet 2 pelleted (0.48 cm. pellet) ; (4) diet 3 ground (0.16 cm. hammermill screen); (5) medium ground corn (1.27 cm. hammermill screen) ; (6) diet 5 pelleted (0.48 cm. pellet) and (7) diet 6 ground (1.27 cm. hammermill screen. Moduli of uniformity and of fineness, respectively, were: expanded corn, 0:5:5 and 2.46; finely ground corn 0:4:6 and 2.07; finely reground pellet, 0:3:7 and 1.91; medium ground corn, 1 : 7:2 and 3.74; medium reground pellet, 1:6:3 and Data were analyzed as in experiment I. Experiment III. One-hundred-sixty crossbred (H x Y) pigs averaging 25.6 kg. were al- TABLE 1. COMPOSITION OF DIET AND SUPPLEMENT Complete Supple- Ingredient diet ~ ment Corn (normal or expanded) Soybean meal () Dicalcium phosphate Ground limestone Salt, iodized Premix.75 ~ 1.0 ~ a Sixteen percent protein diet fed until pigs averaged 45 kg. at which thne corn, soybean meal and d~calcium phosphate were changed to 83.3%, 13.75% and 0.7%, respectively, (13% protein). b Supplied the following per kg. of ration: 1,000 I.l_'. vitamin A, 220 I.U. vitamin D, 11 mcg. vitamin B12, 2.6 rag..riboflavin, 11 rag. calcium pantothenate, 13.2 mg. niacin, 3 rag. copper, 42 rag. iron, 35 mg. manganese, 50 mg. zinc and 22 rag. chlortetracycline (11 rag. in 13% protein ration). c Supplied the following per kg. of supplement: 5,300' I.U. vitamin A, I.U. vitamin D, 55 mcg. vitamin B~, 11 mg. riboflavin, 33 mg. calcium pantothenate, 55 rag. niacin, 11.9 rag. copper, 176 mg. iron, 147 rag. manganese, 200 rag. zinc and 55 mg. chlortetracycline. lotted to 10 treatments with eight females and eight castrate males per pen. The pigs were housed in the same size units as used in experiments I and II. Pigs on treatments one through four received complete mixed diets (CMD) and those on treatments five through 10 were fed corn and supplement (table 1) free-choice (FC). Treatments were: (1) CMD --finely ground corn (0.16 cm. hammermill screen); (2) CMD--finely ground expanded corn; (3) CMD--medium ground corn (1.27 TABLE 2. EFFECTS OF FORM OF CORN AND METHOD OF FEED PREPARATION ON RATE AND EFFICIENCY OF GAIN OF GROWING SWINE, AND ON INCIDENCE OF GASTRIC LESIONS (EXPERIMENT I) Ground corn (hammermill) Rolled corn Shelled Expanded.16 cm cm cm. corn q- Item corn screen screen screen Medium Coarse Supplement Av. daily gain, kgp Rep Rep Av Feed/kg. gain, kg. Rep Rep Av Modulus of fineness b No. normal stomachs c No. cornifications No. erosions No. deaths due to ulcer Mean ulcer index a a Thirty pigs per treatment. Av. initial wt kg. Av. final wt kg. Replicate 1 contained 10 pigs and Replicate 2 contained 20 pigs. b Av. modulus of fineness of diets consumed. e The most severe esophagogastrie condition is recorded for each pig. Five stomachs were not recovered. a The smaller the value, the more severe the condition.

3 ESOPHAGOGASTRIC ULCERS IN SWINE 839 TABLE 3. REGRESSION ANALYSIS OF GAIN (EXPERIMENT I) Partial regression Standard Av. daily gain to 4.5 kg." Intercept Sex (male-female) 0,047**, 0,010 No. pigs per pen (10 to 20) 0,056** 0,010 Modulus of fineness --. 0,24** Gel corn vs. raw corn a --, 038 0,040 Gr. corn vs. whole corn a 0,043 0,027 Rolled corn vs. ground corn d 0,049 0,023 Av. daily gain initial to final wt. b Intercept Sex (male-female) 0.073** No. pigs per pen (10 to 20) 0.023* Modulus of fineness " Get corn vs. raw corn a O. 034 Gr. corn vs. whole corn a Rolled corn vs. ground corn 't Ulcer index ~ Intercept Sex (male-female) No. pigs per pen (10 to 20) ,264 Modulus of fineness 1.450** Gel. corn vs. raw corn a Gr. corn vs. whole corn a * Rolled corn vs. ground corn a "* a R2~ b R-" e R2~ a Sex, no. pigs per pen and modulus of fineness held constant. Indicates P<.05. ~ Indicates t'~.o1. cm. hammermill screen) ; (4) CMD--medium ground expanded corn; (5) FC--finely ground corn; (6) FC--finely ground expanded corn; (7) FC-medium ground corn; (8) FC--medinm ground expanded corn; (9) FC--shelled corn and (10) FC--expanded corn (particle size similar to shelied corn). Moduli of fineness are listed in table 3. The pigs were slaughtered at an average weight of 93.8 kilograms. Results and Discussion Experiment I. The performance data for experiment I are presented in table 2. The results of multiple regression analysis of these data are presented in table 3. The partial regression coefficients for a particular source of variation reflect the influence of this factor on average daily gain or stomach score when the other factors in the analysis are held constant. Castrate males gained significantly (P<.01) faster, kg. per day, than the females from initial to final weight. Daily gains were significantly (P<.05) reduced, kg. per day, by doubling the number of pigs per area of pen space. Increase in the modulus of particle size resulted in a significant (P<.05) decrease of kg. per day in rate of gain. Analysis of the data on stomach ulcer scores showed that each increase in modulus of fineness (table 3) resulted in a significant (P<.01) increase ( ) in stomach ulcer score. These data agree with the previous observations of Mahan et al. (1966) that the incidence of esophagogastric lesions increases as more finely ground diets are fed. Physical form of the diet had a significant (P<.05) effect on the incidence of ulcers. Experiment II. As in experiment I, castrate male pigs gained significantly (P<.01) faster than females ( kg./hd./day) and doubling the number of pigs per area of pen space significantly (P<.05) reduced daily gains ( [-.010 kg./hd./day, table 4). Contrary to the results of experiment I, moduli of fineness did not significantly affect rate of gain; however, the range of particle size was not as great in experiment II. No analysis of feed/gain ratios was made as a Chi square analysis indicated the scored deaths were not independent of treatment. However, the data indicate that the expanded corn diet tended to improve feed conversion. There was little difference in stomach lesions except for the increase in severity (P<.05 in experiment II) and the increased number of deaths of castrate males fed in the 20 pig groups. Castrate males had significantly (P<.05) smaller ulcer indices than did the females (0.701 and pigs from the 20 pig groups had significantly (P<.05) smaller stomach scores ( ) than those from the 10 pig groups (table 5). These trends existed in experiment I but were not significant. It is possible that the additional stress of less favorable weather during this experiment (winter vs. summer) may have resulted in the increased incidence of gastric lesions as suggested by Curtin et al. (1963). No significant difference was noted among treatments in ulcer indices of pigs fed meal, pelleted or reground pellets when sex, number of pigs per pen and modulus of fineness were held constant. Further analysis of ulcer index indicated, as in experiment I, that each decrease in modulus of fineness of the diet resulted in a significant (P<.05) decrease in stomach score ( ). Experiment III. Pig gains were influenced significantly (P<.01) by sex, fineness of diet

4 840 PICKETT ET AL. TABLE 4. EFFECTS OF FORM OF CORN AND METHOD OF FEED PREPARATION ON RATE AND EFFICIENCY OF GAIN OF GROWING SWINE, AND ON INCIDENCE OF GASTRIC LESIONS (EXPERIMENT II) Ground corn (0.16 cm. screen) Ground corn (1.27 cm. screen) Reground Reground Item Expanded Meal Pellet pellet Meal Pellet pellet Av. daily gain, kg. ~ Rep Rep Av Feed/kg. gain, kg. Rep Rep Av Modulus of fineness b ( No. normal stomachs c No. cornifications No. erosions No. ulcers No. deaths due to ulcer Mean ulcer index d a Thirty pigs per treatment. Av. initial wt kg. Av. final wt kg. Replicate 1 contained 10 pigs and contained 20 pigs. b Av. modulus of fineness for diets consumed. Pelleted feeds were.48 cm. pellets of the corresponding ration. ported for pellets are those for the particular texture used in each kind of pellet. e The most severe esophagogastrlc condition is recorded for each pig. Three stomachs not recovered. d The smaller the value, the more severe the condition. replicate 2 Moduli re- and method of feeding (table 6). Castrate males gained faster (0.043 ~0.01! kg./day) than the females as in experiments I and II. Each unit increase in modulus of fineness of the diet again resulted in a significant (P(.01) decrease in rate of gain ( kg./hd./day). Feeding complete mixed diets significantly (P(.01) increased daily gain TABLE 5. REGRESSION ANALYSIS OF GAINS (EXPERIMENT II) Regression Standard Av. daily gain ~ Intercept Sex (male-female) 0.085** Pigs per pen (10 to 20) 0.025* Modulus of fineness Meal vs. reground b Pelleted vs. reground b Expanded vs. reground u Ulcer index ~ Intercept Sex (male-female) " Pigs per pen (10 to 20) 0.836* Modulus of fineness " Meal vs. reground b Pelleted vs. reground ~ Expanded vs. reground b a R2= b Sex, pigs per pen and modulus of fineness held constant. e R2= over that of pigs receiving corn and supplement free-choice (0.048~.012 kg./hd./day). Each unit increase in modulus of fineness resulted in a significant (P~.01) increase in ulcer index. These data agree with those of experiments I and II and further indict finely ground diets as a contributing factor to the occurrence of esophagogastric lesions in swine. Pigs fed expanded corn had significantly (P~.01) lower ulcer indices than pigs fed normal corn. This agrees with reports of Mahan et al. (1966), Perry et al. (1963) and Riker et al. (1967a, b) that the expansion of grains in swine diets increases the incidence of esophagogastric lesions. Summary Three experiments were conducted with growing pigs to study further those factors affecting rate and efficiency of gain and the incidence of esophagogastric ulcers and associated lesions. The factors studied were as follows: gelatinized vs. uncooked corn; fineness of grind of the diet; number of pigs per unit area of floor space and pelleted vs. meal diets. In general, physical form of the diet significantly affected rate of gain and the incidence of esophagogastric lesions of the pigs in these experiments. Castrate males gained

5 ESOPHAGOGASTRIC ULCERS IN SWINE 841 TABLE 6. EFFECTS OF FORM OF CORN, METHOD OF PREPARATION AND METHOD OF FEEDING ON RATE AND EFFICIENCY OF GAIN OF GROWING SWINE, AND ON INCIDENCE OF GASTRIC LESIONS (EXPERIMENT III) Complete mixed rations Finely ground Free choice-corn plus supplement Medium grind Finely ground Medium grind Coarse Item Normal Exp. Normal Exp. Normal Exp. Normal Exp. Normal Exp. Av. daily gain, kg Feed/kg. gain, kg , Modulus of fineness b No. normal stomac~ls" No. cornifications i I No. erosions No. ulcers Ulcer index a a Sixteen pigs per treatment. Av. initial wt., 25.6 kg. Av. final wt, 93.8 kg. b Av. fineness of diet consumed. e Only the most severe esophagogastrlc condition is recorded for each pig. Five stomachs were not recovered. a Normal:10; cornification:8; erosion:5; ulcer=2. significantly faster than females. Reducing the amount of outside pen space from 11.0 to 5.5 my and the amount of house space from 1.1 to 0.55 m3 per pig by doubling the number of pigs per pen resulted in a significant reduction in rate of gain and an increased frequency of esophagogastric lesions. Literature Cited Becker, D. E., A. H. Jonson and B. G. Harmon Fineness of grinding corn and pelleting swine rations. Illinois Agr. Exp. Sta. AS 602d. Chamberlain, C. C., G. M. Merriman and E. R. Lidvall Diagnosis and incidence of experimentally induced gastric ulcers in swine. J. Animal Sci. 23:910. (Abstr.). Curtin, T. M., G. D. Goetsch and R. Hollandbeck Clinical and pathologic characterization of TABLE 7. REGRESSION ANALYSIS OF GAINS (EXPERIMENT III) Regression Standard Av. daily gain Intercept Sex (male-female) "* Gel vs. shelled corn ComDlete ration vs. free choice 0.048"* Modulus of fineness "* Ulcer index" Intercept Sex (male-female) r Gel vs. shelled corn ** ComDlete ration vs. free choice Modulus of fineness 0.466"* a Normal:10; cornification:8; ** P<.01. erosion=5; ulcer:2. esophagogastric ulcers in swine. J. Am. Vet. Med. Assn. 143: 854. Henderson, S. M. and R. L. Perry Agricultural Process Engineering. John Wiley and Sons, New York. Mahan, D. C., R. A. Pickett, T. W. Perry, T. M. Curtin, W. R. Featherston and W. M. Beeson Influence of various nutritional factors and physical form of feed on esophagogastric ulcers in swine. J. Animal Sci. 25:1019. Maxson, D. W., G. R. Stanley, T. W. Perry, R. A. Pickett and T. M. Curtin Influence of various ratios of raw and felatinized corn, oats, oat components and sand on the incidence of esophagogastric lesions in swine. J. Animal Sci. 27:1006. Maxwell, C. V., E. M. Reimann, R. H. Grummer, W. G. Hoekstra, B. A. Muggenburg, T. Kowalczyk and N. A. Reese Effects of oat hulls and ration particle size on the development of gastric ulcers in swine. J. Animal Sci. 25:1248. (Abstr.). Nuwer, A. J., T. W. Perry, R. A. Pickett, T. M. Curtin, W. R. Featherston and W. M. Beeson Value of various additives to ulcer-producing gelatinized corn diets fed to swine. J. Animal Sci. 24:113. Perry, T. W., A. A. Jimenez, J. E. Shively, T. M. Curtin, R. A. Pickett and W. M. Beeson Incidence of gastric ulcers in swine. Science 139:349. Pocock, Elizabeth F., H. S. Bayley and C. K. Roe Relationship of pelleted, autoclaved and heatexpanded corn or starvation to gastric ulcers in swine. J. Animal Sci. 27:1296. Riker, J. T., III, T. W. Perry, R. A. Pickett and T. M. Curtln. 1967a. Influence of various grains on the incidence of esophagogastric ulcers in swine. ]. Animal Sci. 26:731. Riker, J. T., III, T. W. Perry, R. A. Pickett, C. J. Heidenreich and T. M. Curtin. 1967b. Influence of controlled ambient temperatures and diets on the incidence of esophagogastric ulcers in swine. J. Animal Sci. 26:736. Steel, R. G. D. and J. H. Torrie Principles and procedures of statistics. McGraw-Hill Book Co., New York.