EFFECTS OF FEEDER DESIGN (CONVENTIONAL DRY FEEDER, DRY SHELF-FEEDER, AND WET/DRY SHELF-FEEDER) ON FINISHING PIGS

In previous reports from KSU, we demonstrated that wet/dry shelf-feeders supported greater rates and(or) efficiencies of gain compared to conventional dry feeders. However, it has not been demonstrated whether the benefits observed with the wet/dry feeders resulted from the deep-bowl design that might prevent feed wastage or from the wet/dry concept. Thus, we designed an experiment to compare growth performance of finishing pigs when fed from conventional dry feeders and shelf-feeders used to deliver feed in dry or wet/dry form.


Introduction
In previous reports from KSU, we demonstrated that wet/dry shelf-feeders supported greater rates and(or) efficiencies of gain compared to conventional dry feeders.However, it has not been demonstrated whether the benefits observed with the wet/dry feeders resulted from the deep-bowl design that might prevent feed wastage or from the wet/dry concept.Thus, we designed an experiment to compare growth performance of finishing pigs when fed from conventional dry feeders and shelf-feeders used to deliver feed in dry or wet/dry form.

Procedures
A total of 180 finishing pigs with an average initial wt of 118 lb was used in the experiment.The pigs were blocked by weight and allotted to the treatments based on sex and ancestry.The pigs were housed in a modified open-front building (16-ft × 6-ft pen) with 50% solid concrete and 50% concrete slat flooring.There were 12 pigs (six barrows and six gilts) per pen and five pens per treatment.T reatments were: 1) a conventional dry feeder (two-hole stainless steel, Model 1/2 no.2, style B, Smidley Mfg.Co., Dritt, IA); 2) a single-hole shelf-feeder (Model F-5000, Crystal Spring®, Omaha, NE) used dry; and 3) a single-hole shelffeeder used wet/dry with a water nipple located inside the bowl.In the wet/dry feeders, pigs had the choices of eating either dry feed from the shelf or wet feed from the deep bowl.The pens with conventional dry feeders had one nipple waterer mounted against the wall.Each pen was equipped with a water meter (Neptune, Trident™, 5/8 in.× 3/4 in., North Kansas City, MO) to determine water disappearance.All pigs were fed the same corn-soybean meal-based diets (Table 1) formulated to .95%lysine, .6%Ca, and .5% P from 119 to 181 lb and .8%lysine, .5% Ca, and .45%P from 181 to 253 lb body weight.The corn was ground with a roller mill (Roskamp Manufacturing, Model D, Ceder Falls, IA), and the diets were fed in meal form (geometric mean particle size of 626 µm).
Pigs and feeders were weighed on d 0, 31, and before slaughter (d 66) to allow calculation of ADG, ADFI, and F/G.From d 55 to 60 of the experiment, the pigs were fed their diet with .25%chromic oxide added as an indigestible marker.On d 60, samples of feces were collected by rectal massage from four pigs per pen.Concentrations of Cr, DM, and N in the feces and diets were determined to allow calculation of apparent digestibilities of DM and N using the indirect ratio method.On d 66, the pigs were slaughtered, and hot carcass weights were recorded to allow calculation of dressing percentage.Last rib backfat thickness was measured with a ruler at the midline of the split carcass on both sides, and hot carcass weight and last rib backfat thickness were used to calculate fat-free lean index (NPPC, 1994).Finally, the esophageal region of the pigs'stomachs were collected and scored for severity of keratinization and ulceration.The scoring system for keratinization was:.5 = normal, 1 = mild, 2 = moderate, and 3 = severe.The scoring system for ulcers was: .5 = normal, 1 = slight erosion, 2 = ulcer, and 3 = severe ulcer.
All data were analyzed using the GLM procedure of SAS with pen as the experiment unit.Hot carcass weight was used as a covariate for analyses of dressing percentage, last rib backfat thickness, and fat-free lean index.Stomach scores were categorical data; thus, the Cochran-Mantel-Haenszel procedure of SAS (i.e., row mean scores differ test) was used to detect treatment effects.

Results and Discussion
Pigs fed from conventional feeders had ADG, ADFI, and F/G similar to pigs fed from he shelf-feeders (P>.12).However, overall ADG (P<.09) and ADFI (P<.06) tended to be greater when the shelf-feeder was used wet/dry than when it was used dry.Nonetheless, no difference in feed conversion occurred for the overall growth performance.
Pigs fed from the shelf-feeders used 18.3% less water for the overall trial compared to pigs fed from the conventional feeders (P<.08).Also pigs fed from wet/dry feeders used less water than pigs fed from the dry shelf-feeders.
Digestibilities of DM and N, dressing percentage, last rib back fat thickness, and fat-free lean index were not affected by feeder design (P>.57).Finally, scores of stomach lesion (Table 3) were not affected by feeder design.
In conclusion, pigs fed from wet/dry shelf-feeders had the greater ADG and consumed less water compared to pigs fed from dry shelf-feeders.Therefore, the wet/dryfeeding concept, rather than the deep-bowl feeder design, seemed to be of benefit.a A total of 180 pigs (12 pigs per pen and five pens per treatment) with an average initial wt of 118 lb and average final wt of 252 lb was used in the 66 d experiment.

Table 2 . Effects of Feeder Design on Growth Performance, W ater Usage, Nutrient Digestibility, and Carcass Characteristics in Finishing Pigs a
d Dashes indicated P>.15.