Purdue University 1996 Swine Day Report
B. V. Lawrence, D. B. Anderson, O. Adeola, and T. R. Cline
Department of Animal Sciences and Elanco Animal Health
Stomach ulceration in the pig is a serious health concern in the U. S. swine industry, and often results in pig death at approximately 150 lbs live weight or poor finishing pig performance. Ulceration in the pig occurs in the unprotected nonglandular epithelium of the esophageal region of the stomach. Fasting, or major reductions in feed intake, pelleting and fine grinding of the diet, crowding, and transportation have all been implicated as factors which may contribute to ulceration in pigs, and are present in some swine production systems. The factors which have received the most attention are pelleting and fine grinding of the diet. These feed processing methods may result in as much as an 8% improvement in feed efficiency. However, as little as a 3 - 4% death loss due to ulceration during the finishing phase may negate the economic benefits achieved through enhanced feed efficiency. Reported death loss due to ulceration in many herds feeding a finely ground diet following major reductions in feed intake, such as occur during the summer or following a disease outbreak, is much greater than the 4% which is economically acceptable. Before management or treatment strategies can be developed to inhibit ulceration, an understanding of the effect of various management and dietary factors on the esophageal epithelium must be attained. Therefore, the objective of these experiments was to develop a model of the development of ulceration in pigs in response to fasting, transportation, and diet particle size.
Diet composition and particle size. Corn-soybean meal based diets were used in all experiments, with the coarse and fine ground diets having mean particle sizes of 750 and 550 microns respectively.
Fasting, diet particle size, and dietary fat level. A total of 48 barrows, initial weight of 155 lb, were acquired from a commercial source and were individually fed 2.2 lb of a coarse ground diet twice daily for a period of 14 d prior to the start of the experiment. At the end of the 14 d acclimation period, 8 pigs were slaughtered and visual appearance of the stomachs evaluated. The remaining 40 barrows were restrained in metabolism crates and fasted for 24 h. At the end of the 24-h fast, 8 pigs were killed and stomachs evaluated. Twenty-four (8 per dietary treatment) of the remaining pigs were fed approximately 2.4 lb twice daily for 28 d, diets which were either coarse, fine, or finely ground with 8% added fat. The remaining 8 pigs were fed 4.4 lb/d of the fine ground, 8% added fat diet and were fasted for 24 h every 7 d starting on day 3 of the experiment. Intakes of the pigs fed the coarse, fine, and fine + added fat diets were adjusted such that daily nitrogen and energy intakes were similar across treatment groups. Intake of the fasted pigs was not adjusted. After 28 d, all pigs were killed and stomachs evaluated.
Transportation + fasting effects. Sixteen barrows, with an initial weight of 119 lb, were acquired from a commercial source and transported approximately 90 miles in a semi-trailer. Eight pigs were killed immediately upon arrival and the remaining 8 pigs were killed following a 24 h fast. All stomachs were evaluated immediately following slaughter.
Diet particle size following transportation and fasting. Seventy barrows, with an average initial weight of 133 lb, were acquired from a commercial source and transported approximately 90 miles in a semi-trailer. Upon arrival, 10 pigs were killed immediately and the stomachs evaluated. The remaining 60 pigs were individually penned and 50 of these pigs were fasted for 24 h, while 10 barrows were offered 2.2 lb of a coarse ground diet. Twenty-four hours after arrival, the 10 pigs with access to feed and 10 of the fasted pigs were killed and the stomachs evaluated. The remaining 40 barrows were fed 2.2 lb of either a coarse or a fine ground diet twice daily for either 3 or 7 d after arrival before being slaughtered and stomachs evaluated for signs of ulceration.
Coarse ground diet following fasting. A total of 48 barrows weighing an average of 138 lb were acquired from a commercial source and fed 2.2 lb of a coarse ground diet twice daily for 14 d. Eight of the barrows were slaughtered at the end of the 14-d acclimation period and the stomachs evaluated. The remaining 40 barrows were moved to metabolism crates and 32 of the 40 were fasted for 24 h, while 8 pigs were fed their normal meal. After being in the metabolism crates for 24 h, 8 of the fasted pigs and the 8 pigs which had been fed were slaughtered and stomachs evaluated. The remaining pigs were killed after being fed a coarse ground diet for 3, 7, or 14 d.
Development of esophageal ulceration in the pig stomach. The esophageal region of the pig stomach is actually a continuation of the esophagus which extends down into the stomach. In contrast to the rest of the stomach which is protected by a thick mucous coat, the esophageal region's only defense is a thick layer of epithelium, which is the same type of cells from which skin is derived. Under normal circumstances, this epithelial layer is rather thick, has a pearly white consistency, and is extremely pliable. Ulceration of the esophageal epithelium initially manifests itself as a keratinization, or hardening, of the epithelial cells. When keratinization occurs, the cells begin to die and absorb a yellow stain from bile which has been refluxed from the small intestine into the stomach. Erosion, or sloughing off, of the surface epithelial layer typically occurs following keratinization. Ulceration develops following erosion and results in bleeding from the esophageal region and swelling of the area around the ulcer. Swelling of the esophageal region may result in the closure of the esophageal opening.
Fasting, diet particle size, and dietary fat level. Pigs fed the coarse and fine ground diets were fed 4.8 lb/d of their respective diet and the pigs fed the fine ground diet with 8% added fat consumed 4.5 lb/d, resulting in daily lysine and energy intakes of 18.7 g and 7.69 Mcal respectively. Growth performance (1.6 vs. 1.8 lb/d) and feed efficiency (.34 vs. .37) were not affected by diet particle size (coarse vs. fine). Addition of 8% fat to the finely ground diet also did not improve growth (1.8 vs. 1.7 lb/d) or feed efficiency (.37 vs. .39). Evaluation of the esophageal region of the stomach from the pigs which were slaughtered at the end of the 14-d acclimation period revealed that most pigs had a normal esophageal epithelium with some slight keratinization. Following a 24-h fast, the esophageal epithelium had undergone drastic changes which resulted in erosion of the epithelium. When a coarse ground diet was fed for 28 d, the erosion observed following a 24-h fast was replaced with a normal epithelial covering. However, when a fine ground diet was fed, the erosion present following the 24-h fast was maintained throughout the 28-d study. Addition of 8% fat to the diet, or a repeated 24-h fast every 7 d, did not increase the severity of the erosion which was maintained by the fine ground diet.
Transportation + fasting effects. Evaluation of the gross visual appearance of the esophageal region of the pig stomach immediately following transportation via semi-trailer for 90 miles indicated a normal esophageal epithelium with no abnormalities present. When the pigs were fasted for 24 h following transportation, the esophageal epithelium of the stomach appeared to have undergone keratinization, with some erosion of the epithelium also present.
Diet particle size following transportation and fasting. Keratinization with moderate amounts of erosion of the esophageal epithelium was observed following transportation in the pigs that were fasted for 24 h, with keratinization and slight erosion observed in the stomachs of the pigs which were allowed access to feed. Intakes during the 24 h following transportation for the pigs which were allowed access to feed were only approximately 50% of the feed intakes of comparable weight pigs. The keratinization and erosion present in both the fasted and fed pigs was in contrast to the normal epithelial lining which was present in the pigs slaughtered immediately after transportation. Feeding a coarse ground diet for 7 d following transportation and fasting allowed the esophageal epithelium to attain a more normal appearance with only a slight degree of keratinization. However, feeding a fine ground diet for 7 d following transportation and a 24-h fast maintained the keratinization and erosion induced by transportation and fasting.
Coarse ground diet following fasting. The esophageal region of the pig stomach had a normal appearance following the 14-d acclimation period. Following a 24-h fast, keratinization with some erosion was present. However, the esophageal epithelium of stomachs was normal in the pigs which were offered their regular meals following being placed in metabolism crates. Feeding a coarse ground diet for as little as 3 to 7 d allowed the esophageal epithelium to regain a normal appearance.
Results of these experiments indicate that the esophageal region of the pig stomach is extremely susceptible to damage induced by fasting, or severe depressions in feed intake. Furthermore, the damage induced by alterations in feed intake appear to be maintained when a fine ground diet is fed. However, feeding a coarse ground diet for as little as 7 d may be sufficient to allow the esophageal epithelium to regenerate and resume a normal appearance. The failure to observe significant differences in growth and feed efficiency in response to diet particle size may be attributable to the relatively small difference in diet particle size (750 vs. 550 microns) between the coarse and fine treatment groups, or due to the restricted feeding regimen. These results suggest that feeding a coarse ground diet (>750 micron) for at least 7 d following movement of pigs, or following periods when feed intake has been severely depressed for as little as 24 h, may reduce the probability of the pigs subsequently developing hemorrhagic ulceration.
Use of a feeding strategy which includes intermittent feeding of a coarse ground diet for at least 7 d, followed by a period during which a fine ground diet is fed, may allow swine producers to take advantage of the 5 to 8 % improvement in feed efficiency associated with feeding a fine ground diet while avoiding the poor performance and death loss associated with ulceration.
Index of 1996 Purdue Swine Day Articles
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