Twelve commercial models of feeders were classified into 4 groups:\u00a0single-space dry (2 models), multiple-space dry (4), single-space wet\/dry (3), and multiple-space wet\/dry\u00a0(3) and used as the basis for most of the studies.\u00a0Feeders that provided less than 34 cm of feeding width resulted in crowding with market\u00a0weight pigs. However, feeding spaces wider than 39 cm increased the frequency of two small pigs eating
\nsimultaneously. Side panels more than 34 cm long provided better protection to pigs while eating,\u00a0reducing the frequency of displacements from the side.\u00a0Small pigs frequently stepped into feeders which were more than 27 em deep (lip to\u00a0feed), and those from which pigs ate from an angled body position.<\/p>\n
The feeders were evaluated for their effects on production traits- average daily feed intake (ADFI),\u00a0average daily gain (ADG), feed efficiency and carcass quality – of grower\/finisher pigs. Each\u00a0model was used by 4 pens of 12 pigs in 12-wk trials under an incomplete block balanced design.\u00a0ADG and ADFI were 5% greater with wet\/dry feeders than with dry (P<0.05). The effect of\u00a0wet\/dry feeders on growth was only evident during the final 8 wk of the trial (P<0.05). ADFI\u00a0tended to be higher with wet\/dry feeders throughout the trial (P<0.05). Pigs using single and\u00a0multiple space feeders did not differ in either gain or intake during any of the trial periods\u00a0(P>0.05). Feed efficiency did not differ among feeder classes. Dry feeders yielded a slightly\u00a0higher ( 1 %) lean percentage of carcass than did wet\/dry feeders (P<0.05).<\/p>\n
During the production study, the pigs were videotaped and their eating behaviour analyzed. The total\u00a0duration of eating varied from less than 75 to over 115 min\/day per pig. and the number of displacements\u00a0(entrances) from less than 30 to over 80 per pig per day. on the different feeders. Large pigs spent less\u00a0time eating than did small pigs, but spent longer in the feeder per entrance Wet\/dry feeders also resulted
\nin reduced eating time. with an increase in eating speed of approximately 25% compared to dry feeders.\u00a0Pigs spent less time eating from single space feeders than from multiple space feeders, but this was\u00a0associated with shorter durations per entrance into the feeder. The combined effects of single space and\u00a0dry features in a feeder resulted in an average feeder occupancy rate in excess of 80%. which would be\u00a0higher still for small pigs.<\/p>\n
All models were within the\u00a0range for a feed spillage rate of 2-5.8% of offered feed.\u00a0The size\u00a0of pig had an effect on feed wastage. Although large and small pigs spilled the same absolute amount of\u00a0feed, spillage as a percentage of feed disappearance was greater for small (4.4%) compared to large\u00a0(2.4%) pigs. Leavage within the feeder was greater for large than for small pigs. The differences\u00a0between feeder categories (dry vs. wet\/dry, single vs. multiple space) were not statistically detectable.\u00a0The occurrence of feed spillage due to eating, fighting and stepping into feeder was affected by the\u00a0size of pig (P<0.05).<\/p>\n
Two tests were conducted to study the eating speed of grower\/finisher pigs. In the first test, hungry pigs\u00a0were allowed access to each model for a set period of time. Although no differences among feeder\u00a0categories (dry vs. wet\/dry; single vs. multiple space} were detected for eating speed in this test, large\u00a0pigs ate faster than small ones (P < 0.05) and lever-operated feeders resulted in a lower eating speed than\u00a0non-lever feeders (P < 0.05). The second test compared eating speeds of pigs fed a fixed amount of\u00a0either premixed wet feed or dry mash feed. Pigs on premixed wet feed ate about 3 times faster than ‘did\u00a0those on dry feed (P < 0.05).<\/p>\n
Five ergonomic studies were conducted using a specially designed feeder on which the lip height,\u00a0feeder depth (front to back), width, and feeding shelf height could be adjusted. Pigs were tested at\u00a0various weights from 22 to 96 kg. The effects of pig size, feeder depth and lip height on the\u00a0incidence of pigs stepping into the feeder was evaluated. Within the\u00a0constraints of the experimental design, with limits placed on feeder depth and lip height, small pigs\u00a0stepped into the feeder more often. The most significant design feature of the feeder for this\u00a0behaviour was feeder depth. Stepping in was more common as feeder depth was increased, but the\u00a0point at which it began varied with the size of pig. Grower pigs stepped into a feeder with a depth\u00a0of 20 em, but large pigs did not do so until the depth was 30 em or more. Lip height had only a\u00a0minor influence on stepping-in, and only at critical depths that depended upon pig weight. The distance from the toe of the pig to its\u00a0snout increased with pig weight and was similar to the feeder depths resulting in the lowest\u00a0frequency of stepping-in. A final factor related to feeder dimensions is the restriction the feeder lip\u00a0places on accessing feed at the front of the feeder. This restriction decreases as pigs grow, but\u00a0should be accommodated in feeder design by providing a slope behind the lip of the feeder.<\/p>\n
Two studies examined the angles of the body and head while pigs ate. Pigs prefer to stand\u00a0at an angle of approximately 30\u00b0 to the feed access, but in restrictive feeders will turn their heads to\u00a0obtain some angled approach. Pigs also rotate their heads approximately 45-55″ while eating to\u00a0improve access to the feed.<\/p>\n