Effects of season, truck type, and location within truck on gastrointestinal tract temperature of market-weight pigs during transport.

Two experiments were done to assess the effects of season, truck type, and location in the truck on the gastrointestinal tract temperature (GTT) of market-weight pigs during transport. In Exp. 1, a total of 504 sentinel pigs were selected from a total load of 3,756 pigs over 12 wk in summer or winter and transported in either a double-decked (DD) hydraulic truck or a pot-belly (PB) trailer for 2 h. In Exp. 2, a total of 330 sentinel pigs were selected from a total load of 2,145 pigs over 11 wk in summer or winter and transported in a PB trailer for 8 h. In both experiments, sentinel pigs were equipped with a temperature data logger for the real-time GTT recording from the farm to slaughter. Transport was divided into 8 periods in Exp. 1 (rest, pretravel, initial travel, prearrival 1, prearrival 2, unloading, lairage 1, and lairage 2) and in Exp. 2 (rest, pretravel 1, pretravel 2, travel, prearrival 1, prearrival 2, lairage 1, and lairage 2). A delta GTT (ΔGTT) was calculated as the difference between the measured GTT at any determined event and the GTT measured at rest. In Exp. 1, the ΔGTT of pigs was greater ( < 0.001) in summer than in winter and only during the pretravel and initial travel periods. No difference was observed in the ΔGTT between the 2 truck types ( > 0.10). In summer, pigs located in the front top and rear top compartments of the PB trailer presented greater ( < 0.05) ΔGTT values than those transported in the middle top and front belly compartments during initial travel. In summer, during prearrival 1 and 2, a greater ( < 0.05) loss of GTT was found in pigs located in the rear top compartment of the DD truck compared with the rear lower compartment and in the front middle compartment compared with the rear middle compartment of the PB trailer. In Exp. 2, the ΔGTT of pigs was greater ( = 0.03) in summer than in winter during pretravel 2. Pigs in the front top compartment had a greater ( < 0.05) ΔGTT compared with pigs in the middle top, lower deck, and front belly compartments during the pretravel periods. Based on the results of the 2 experiments, modifications of the PB trailer model are recommended to limit body temperature increase due to physical stress at loading and unloading, and during transport due to inconsistent ventilation rate across vehicle locations.

Effect of rest duration on recovery from repeated exercise in near-market-weight pigs.

The process of transportation can be seen as a succession of stressors, from which pigs may not have time to recover before slaughter. The aim of this study was to determine the extent to which the duration of the rest time given to near-market-weight pigs after an initial exposure to exercise affected their recovery from subsequent exercise. Eighteen groups of 3 gilts were exercised (Ex1) through a standard handling course, including two 19° ramps, and then were held in a holding pen for either 35 (RT35), 75 (RT75), or 150 (RT150) min (Rest Period 1, RP1). Afterward, pigs were exercised a second time (Ex2) and left to rest for 150 min. Recovery from Ex2 (Rest Period 2, RP2) was assessed using measures of heart rate (HR), respiratory rate (RR), skin temperature (ST), and posture. Repeated measures and regression analysis were used to analyze the data. For RT75 pigs, there were no detrimental effects of Ex2 on HR, RR, and handling time (P > 0.05, for all) during the exercise and recovery periods. Skin temperature during Ex2 was greater than ST during Ex1 (P < 0.001), whereas ST during RP1 did not differ from ST during RP2 (P > 0.05). Doubling the rest period did not provide any more beneficial effects in regard to RR and HR (P > 0.05 for both) during Ex2 and RP2 compared to RT75 pigs, as shown by the similar latencies to recover for these 2 variables. However, ST did not increase between exercises, and RT150 pigs required less time to complete the handling course during Ex2. The results show that a lack of rest after an initial exposure to exercise made pigs more susceptible to stress during Ex2 and RP2, as demonstrated by greater (P < 0.001 for all) HR, RR, and ST during RP2 compared to RP1 and Ex2 compared to Ex1. When given more than 35 min to rest during RP2, RT35 pigs eventually recovered. Latencies of recovery for HR, ST, RR, and posture were all greater (P < 0.05 for HR, ST, and RR and P < 0.001 for posture) than those obtained for RT75 and RT150 pigs. This study highlights that if pigs are not initially given enough rest to recover from exercise, a subsequent exposure to the same exercise will cause an increase in these physiological variables during exercise and recovery. Further research is needed to investigate factors contributing to the quality of rest, with a particular focus on conditions not allowing a proper rest on the truck or in lairage.

Effects of transport duration on maintenance behavior, heart rate and gastrointestinal tract temperature of market-weight pigs in 2 seasons.

Welfare and meat quality of market-weight pigs may be negatively affected by transport duration and environmental temperatures, which vary considerably between seasons. This study evaluated the effects of 3 transport durations (6, 12, and 18 h) on the physiology and behavior of pigs in summer and winter in western Canada. Market-weight pigs were transported using a pot-belly trailer at an average loading density of 0.375 m(2)/100 kg. Four replicates of each transport duration were conducted during each season. Heart rate and gastrointestinal tract temperature (GTT) were monitored from loading to unloading in 16 pigs from 4 selected trailer compartments (n = 96 groups, total of 384 animals, BW = 120.8 ± 0.4 kg), namely top front (C1), top back (C4), middle front (C5), and bottom rear (C10). Behavior was recorded for pigs (948 and 924 animals, in summer and winter, respectively) in C1, C4, and C5 during transportation (standing, sitting, lying), and during 90 min in lairage (sitting, lying, drinking, latency to rest) for pigs in all 4 compartments. Transport was split into 7 periods: loading, pre-travel (PT), initial travel (IT), pre-arrival 1 (PA1) and 2 (PA2), unloading, and lairage. During IT and PA2, pigs spent less time lying in winter than summer (P < 0.05 and P < 0.05, respectively). During PA1, PA2, and unloading, a greater (P < 0.001) heart rate was found in pigs transported in winter compared with summer. During PA2, pigs subjected to the 18-h transport treatment in winter had a greater (P < 0.05) GTT than the other groups. In lairage, pigs transported for 18 h in winter drank more (P < 0.001) and took longer to rest (P < 0.01) than pigs from other groups. During PA1, pigs transported for 18 h had the greatest GTT (P < 0.001). At unloading, pigs transported for 6 h had the lowest GTT (P < 0.001). In lairage, pigs transported for 18 h spent less time lying than those transported for 6 or 12 h (P < 0.001). These results suggest that in winter, pigs increased their metabolism and were reluctant to rest on cold floors. Pigs transported for 18 h in winter showed greater evidence of thirst. It may be concluded that under western Canadian climatic conditions, long transports (18 h) in cold weather appear to be more detrimental to pig welfare.

Effect of ramp configuration on easiness of handling, heart rate, and behavior of near-market weight pigs at unloading.

Three experiments, each using 280 pigs, were conducted in a simulated compartment to test the effect of angle of entrance (AOE) to the ramp (90°, 60°, 30°, or 0°), ramp slope (0°, 16°, 21°, or 26°), and an initial 20-cm step associated with 16° or 21° ramp slopes on the ease of handling, heart rate (HR), and behavior of near market-weight pigs during unloading. Heart rate (pigs and handler), unloading time, interventions of the handler, and reactions of the pigs were monitored. The results of the first experiment show that using a 90° AOE had detrimental effects on ease of handling (P < 0.05), HR of the pig (P < 0.05), and behavior (P < 0.05). The 0° and 30° AOE appeared to improve the ease of unloading, whereas the 60° AOE had an intermediate effect. The 30° AOE appeared to be preferable, because pigs moved at this angle balked less frequently (P < 0.01) and required less manipulation (P < 0.05) than pigs moved with a 0° AOE. The results of the second experiment show that the use of a flat ramp led to the easiest unloading, as demonstrated by the lower number of balks (P < 0.001) when pigs were moved to the ramp and less frequent use of paddle (P = 0.001) or voice (P < 0.001) on the ramp, compared with the other treatments. However, the flat ramp did not differ from the 21° ramp in many of the variables reflecting ease of handling, which may be explained by the difference in configuration between the ramps. The results also show that the use of the steepest ramp slope had the most detrimental effect on balking and backing up behavior of pigs (P < 0.001), and handling (touches, slaps, and pushes; P < 0.05 for all) when moved to the ramp and on unloading time (P < 0.01). No differences in pig HR (P < 0.05) and ease of handling on the ramp (P < 0.05) were found between a 26° and 16° ramp slope, suggesting that the length of the ramp may be one of the factors that make unloading more difficult. The results of the last experiment show that an initial step made unloading physically more demanding for the handler (P < 0.001) and pigs on the ramp (P < 0.05) as demonstrated by their greater HR. The greater difficulty of handling (P < 0.01) and reluctance to move (P < 0.05) of pigs moved toward the 16° ramp with a step suggest that pigs perceived this ramp as more psychologically challenging. Making a few changes in terms of the design of the ramp could improve the efficiency of handling and reduce stress in pigs.

Transportation of market-weight pigs: II. effect of season and location within truck on behavior with an eight-hour transport.

Transportation of pigs to slaughter has the potential to negatively impact animal welfare, particularly in hot temperatures and over long transport durations. The objective of this experiment was to determine if season and location within vehicle influenced the behavior of market-weight pigs during loading, transit, unloading, and lairage after a long-distance trip to slaughter. On a pot-belly truck, 1,170 pigs were transported (n = 195 pigs/wk in 7 experimental compartments) for 8 h to a commercial abattoir in summer (6 wk) and winter (5 wk). Pig behavior was observed at loading, in transit, at unloading, and in lairage. Handler intervention at loading was observed, and the time to load and unload was recorded. Although season did not (P = 0.91) affect loading time, more prods (P = 0.014) were necessary to load pigs in summer than winter. Loading in winter also tended to be longer (P = 0.071) into compartments involving internal ramps. In transit, more pigs (P = 0.025) were standing in winter compared with summer. Unloading took longer (P < 0.006) in winter than in summer and from compartments where pigs had to negotiate ramps and 180° turns. Furthermore, pigs in summer experienced more slipping (P = 0.032), falling (P = 0.004), overlapping (P < 0.001), and walking backward (P < 0.001) than pigs in winter. Pigs unloading from compartments with internal ramps slipped more (P < 0.0001) than other pigs. Season influenced latency to rest in lairage, with those transported in summer resting sooner (P < 0.0001) than those in winter. In conclusion, season and location within trucks differentially affect pig behavior before, during, and after long-distance transportation. Differences in lighting and temperature between seasons and the inclusion of internal ramps within vehicles may play important roles in the welfare of pigs transported to slaughter.

Transportation of market-weight pigs: I. effect of season, truck type, and location within truck on behavior with a two-hour transport.

There is evidence that season and truck/trailer design play important roles in pig welfare during transportation although little is known about their interaction and effect on pig behavior. This experiment was designed to examine the influence of season and truck/trailer design on the behavior during loading, transit, unloading, and lairage of market-weight pigs transported to slaughter. A total of 3,756 pigs were transported on either a 3-deck pot-belly trailer (PB; n = 181 pigs/wk in 8 experimental compartments) or a double-decker hydraulic truck (DD; n = 85 pigs/wk in 4 compartments) for 2 h to a commercial abattoir in summer and winter (6 wk in each season). Density on both vehicles was 0.40 m(2)/pig. Accounting for the number of pigs, loading took longer (P = 0.033) onto the DD than the PB, but season did not (P = 0.571) influence loading time. Pigs loaded onto the PB moved backward more (P = 0.003) frequently than those loaded onto the DD. The frequency of tapping by handler was the lone handling intervention affected by truck type, with more (P = 0.014) tapping needed to move pigs on and off DD than PB. During loading, pigs made more (P < 0.001) slips and falls, overlaps, 180° turns, underlaps, and vocalizations in winter compared with summer. On truck, more (P < 0.001) pigs were standing on the DD at the farm and in transit than on the PB whereas more (P = 0.012) pigs were lying in transit in summer than in winter. Pigs took longer to unload (P < 0.001) from the PB than the DD, but no difference between vehicles (P = 0.473) in latency to rest in lairage was found. Pigs slipped and fell more (P < 0.001) during unloading, took longer (P < 0.001) to unload, and had a shorter (P = 0.006) latency to rest in lairage in winter than summer. Vehicle design, in particular the presence of ramps, influenced pig behavior before, during, and after transportation, regardless of the season. Season affected loading and unloading behavior, especially in terms of slips and falls on the ramp, and differences in truck/trailer designs were also partly to blame for unloading times and lairage behavior. Ramps and changes in direction during unloading appear to slow down the handling process.

Effects of different moving devices at loading on stress response and meat quality in pigs.

Although there is increasing evidence regarding the negative welfare and meat quality implications of electric prod use for slaughter-weight pigs, this handling tool continues to be used. Therefore, the behavioral and physiological response and carcass and meat quality of 360 pigs being loaded onto a truck for transportation to slaughter according to 3 handling procedures were studied. The 3 handling procedures were 1) moving with an electric prod and board from the finishing pen to the truck (EP); 2) moving with a board and a paddle from the finishing pen to the truck (PAD); 3) moving with a board and a paddle from the finishing pen and using a compressed air prod in the ramp before going into the truck (CAP). A subpopulation of 144 pigs (48 pigs/treatment) was equipped with heart rate monitors. Blood samples were collected from the same animals at exsanguination for the analysis of creatine phosphokinase and lactate. Data were analyzed using an ANOVA for factorial design, with the animal as the experimental unit. Behavior was analyzed with MIXED model procedure with treatment as a fixed effect. During loading, EP pigs slipped and fell (P < 0.001) and overlapped (P = 0.03) more often, but stopped (P < 0.001) and attempted turns (P = 0.01) less often than CAP or PAD. With CAP, pigs made more 180° turns (P = 0.01) than with PAD or EP. Loading with EP led to more and longer vocalizations (P = 0.02 and P = 0.001, respectively) than loading with CAP or PAD. Loading took longest with CAP and was quickest with EP (P = 0.01). Pigs handled with EP had a greater heart rate than those moved with PAD and CAP at loading (P < 0.001), wait at loading (P < 0.001), at unloading (P = 0.05), and in lairage (P = 0.02). Pigs loaded with EP had greater (P = 0.05) lactate concentrations in blood at exsanguination compared with pigs handled with CAP, with pigs loaded with PAD being intermediate. Furthermore, ultimate pH values in the semimembranosus and adductor muscles of EP pigs were greater (P = 0.002 and P = 0.004, respectively) compared with those from PAD and CAP pigs. Greater (P = 0.04) incidence of blood-splashed hams was found in EP pigs compared with PAD and CAP pigs. Therefore, considering animal welfare, carcass bruising, and blood splashes standpoints, EP should be replaced with PAD or CAP. However, additional research is necessary to identify methods that improve the loading efficiencies of PAD and CAP without adversely affecting animal welfare parameters.

Effects of housing finishing pigs in two group sizes and at two floor space allocations on production, health, behavior, and physiological variables.

With the current shift in the industry toward housing pigs in groups of 100 to 1,000 per pen have come questions as to whether pigs can perform as well in large groups as they do in small and whether large groups of pigs can use the space provided more efficiently. This study examined effects of small (18 pigs) vs. large (108 pigs) group sizes provided 0.52 m(2)/ pig (crowded) or 0.78 m(2)/pig (uncrowded) of space on production, health, behavior, and physiological variables. Eight 7-to 8-wk-long blocks, each involving 288 pigs, were completed. The average BW at the beginning of the study was 37.4 +/- 0.26 kg. Overall, ADG was 1.032 kg/d and 1.077 (+/-0.015) kg/d for crowded and uncrowded pigs, respectively (P = 0.018). Differences between the space allowance treatments were most evident during the final week of study. Overall G:F was also reduced (P = 0.002) in the crowded treatment. Pigs in the crowded groups spent less (P = 0.003) time eating over the 8-wk study than did pigs in noncrowded groups, but ADFI did not differ (P = 0.34) between treatments. Overall, ADG of large-group pigs was 1.035 kg/d, whereas small group pigs gained 1.073 kg/d (+/-0.015; P = 0.039). Average daily gain differences between the group sizes were most evident during the first 2 wk of the study. Over the entire study, G:F also differed, with large groups being less efficient (P = 0.005) than small groups. Although large-group pigs had poorer scores for lameness (P = 0.012) and leg scores (P = 0.02) throughout the 8-wk period, morbidity levels did not differ (P = 0.32) between the group sizes. Minimal changes in postural behavior and feeding patterns were noted in large groups. An interaction (P = 0.04) of group size and space allowance for lameness indicated that pigs housed in large groups at restricted space allowances were more susceptible to lameness. Although some behavioral variables, such as lying postures, suggest that pigs in large groups were able to use space more efficiently, overall productivity and health variables indicate that pigs in large and small groups were similarly affected by the crowding imposed in this study. Broken-line analysis of ADG indicated no difference in the response to crowding by pigs in large and small groups. Little support was found for reducing space allowances for pigs in large groups.

Effect of environmental enrichment at two stages of development on belly nosing in piglets weaned at fourteen days.

The incidence of belly nosing-related behaviors was studied in 480 piglets weaned at 14 d and provided with environmental enrichment during preweaning, postweaning, or both. Pen enrichment was achieved by providing a foam rubber mat on the pen wall (nose), rubber nipples (suck), a Bite-Rite Tail Chew (bite), a soil-filled tray (root), or no enrichment (control). Instantaneous scan sampling observations, at 5-min intervals, were conducted for 8 h (i.e., 96 scans/observation day) at 3, 10, 19, 26, and 33 d. Observations during the preweaning phase were made to determine the number of piglets lying, standing, nursing, and interacting with environmental enrichment. During the postweaning phase, observations were made to determine the number of piglets belly nosing, belly sucking, other nosing and sucking (other), biting, eating, drinking, and interacting with enrichment. The time-course for belly nosing was confirmed, with the behavior rising by 19 d, peaking by 26 d, and decreasing by 33 d (P < 0.001). Only nosing enrichment was found to reduce the incidence of belly-nosing behavior (3.8%) compared with controls (6.6%; P < 0.001). Pigs provided root enrichment spent more time manipulating their enrichment devices (30.2%) compared with all other enrichment groups (P < 0.001). Providing enrichment relevant to a particular behavioral vice as it commences, or shortly afterward, may have the greatest effect on reducing the incidence of that vice during the nursery period.

Use of supplementary tryptophan to modify the behavior of pigs.

Three experiments were conducted to investigate the short-term use of supplementary Trp on the behavior of grow/finish pigs. Three levels of dietary Trp were used, representing the standard requirement for growth (control), twice (2x), and 4 times (4x) the control amount. In Exp. 1, pigs were fed the diets for 7 d, during which observations were made of their general behavior (time budget), aggression within the group of familiar pigs, and response to a startling auditory stimulus. Behavior effects were evident during the period of supplementation for both the 2x and 4x diets. During the treatment period, pigs fed supplemental Trp spent more time lying (P = 0.04) and less time eating (P = 0.05) than pigs fed the control diet. Although the response of the animals to the startling stimulus was to become alert and stand, similar behavioral effects caused by supplemental Trp also were evident after the startling stimulus (P < 0.01). Based on these observations, the subsequent studies retained the same dietary levels of Trp and incorporated a 3-d feeding of diets before behavior testing. In Exp. 2, pigs were fed the experimental diets for 3 d before being regrouped with unfamiliar pigs on the same diet. Subsequent aggression was affected by Trp supplementation, in that high levels of dietary Trp decreased the total duration of fighting by approximately 50% (P = 0.03). Supplemental Trp had no effect on the number of fights, and there were no differences between the 2 levels of supplemental Trp on any behavior. In Exp. 3, pigs were exposed to specific handling tests on the farm and meat quality assessments after being fed the experimental diets for 3 d. There were no differences among dietary treatments for any of the meat quality characteristic variables measured. The only behavioral or physiological difference observed among the treatments was a slower movement of pigs fed the 4x Trp treatment than control or 2x Trp-fed pigs in a minimal-forced situation (P = 0.04). Response to confinement on a scale, an electric prod, and movement in general did not differ among treatments. High levels of Trp may result in animals avoiding stressful situations if possible, but they seem to have no effect on responses to stressors that animals may experience in a forced situation.

Application of broken-line analysis to assess floor space requirements of nursery and grower-finisher pigs expressed on an allometric basis.

Few issues in swine production are as complex as floor space allowances. One method for pork producers to calculate floor space allowance (A) is to convert BW into a 2-dimensional concept yielding an expression of A = k * BW(0.667). Data on ADG, ADFI, and G:F were obtained from published peer-reviewed studies. Five data sets were created: A = grower-finisher pigs, fully slatted floors, and consistent group size; B = grower-finisher pigs and fully slatted floors (group size did not need to be consistent); C = grower-finisher pigs, partially slatted floors, and consistent group size; D = grower-finisher pigs, partially slatted floors (group size did not need to be consistent); and E = nursery pigs, fully slatted or woven wire floors (group size did not need to be consistent). Each data set was analyzed using a broken-line analysis and a linear regression. For the broken-line analyses, the critical k value, below which a decrease in ADG occurred, varied from 0.0317 to 0.0348. In all cases the effect of space allowance on ADG was significant (P < 0.05). Using the linear analyses based on data with k values of < 0.030, the critical k values for the 4 grower-finisher data sets did not differ from those obtained using the broken-line analysis (0.0358 vs. 0.0336, respectively; P > 0.10); however, none of the linear regressions explained a significant proportion of the variation in ADG. The slopes for the nonplateau portion of the broken-line analyses based on percent values varied among data sets. For every 0.001 decrease in k (approximately 3% of the critical k value), ADG decreased by 0.56 to 1.41%, with an average value of 0.98% for the 5%-based analyses. The use of an allometric approach to express space allowance and broken-line analysis to establish space requirements seem to be useful tools for pig production. The critical k value at which crowding becomes detrimental to the growth of the pig is similar in full- and partial-slat systems and in nursery and grower-finisher stages. The critical point for crowding determined in these analyses approximated current recommendations to ensure the welfare of pigs.

Water intake and wastage at nipple drinkers by growing-finishing pigs.

Three experiments were conducted to assess water intake, water wastage, and a means to decrease water wastage by growing-finishing pigs from nipple drinkers. In Exp. 1, 48 pigs were studied during two periods (average BW = 53 and 72 kg for Period 1 and 2, respectively). Water disappearance and wastage were determined for 4 d, while nipple drinkers were set at 50 mm above the shoulder height of the smallest pig in the pen (recommended heights), with flow rates at 700 mL/min during Period 1, and 1,000 mL/min during Period 2. Water intake rate was assessed at two nipple flow rates, approximately 650 and 1,300 mL/min during the Period 1, and 1,000 and 2,000 mL/min during the Period 2. The average water intake was 4.01 and 5.38 +/- 0.19 L.pig(-1).d(-1) during Periods 1 and 2, respectively (P < 0.01). Water wastage as a percentage of water disappearance was similar between the two periods (25.8 and 27.0 +/- 1.9% for Periods 1 and 2, respectively). Water intake rate was 467 and 795 mL/min (+/-34.2; P < 0.01) during Period 1, and 722 and 1,422 mL/min (+/-80.0; P < 0.01) during Period 2, at the lower and higher flow rates, respectively. In Exp. 2, 32 pigs were used in a 2 x 2 factorial design to determine effects of nipple heights (recommended vs. unadjusted = 330 mm) and flow rates (500 vs. 1,000 mL/min) on water intake and wastage. Water wastage was increased (P < 0.01) on the unadjusted vs. recommended nipple height, and the higher flow rate also resulted in greater wastage (P = 0.03) compared with the lower rate. In Exp. 3, water disappearance and manure output in 16 pens of 18 pigs per pen were monitored for 12 wk (average initial BW = 32 kg) using four drinker treatments (bowl drinker, nipple drinker at recommended heights, an unadjusted nipple set at 480 mm, and high nipple drinker height of 730 mm with a step underneath). For pigs on the high nipple drinker, the average water disappearance and manure output did not differ from those of the pigs on the recommended nipple heights and bowl drinker, but these measurements were 15 and 12% lower, respectively, than for the pigs on the low nipple drinker. The results indicate that growing-finishing pigs can maintain adequate water intake from a variety of drinker types and management. Water wastage can be controlled through drinker management.

Effect of group size on performance of growing-finishing pigs.

Six hundred forty growing-finishing pigs (initial BW = 23.2 +/- 4.8 kg) were used in a 12-wk study (final BW = 95.5 +/- 10.2 kg) to quantify the effects of group size (10, 20, 40, and 80 pigs/pen) on performance, tail biting, and use of widely distributed feed resources. One single-space wet/dry feeder was provided for every 10 pigs, and floor allowance was 0.76 m2/pig in all treatment groups. Weight gain and feed intake were measured every 2 wk. At weighing, a tail-biting injury score was given to each pig. Blood samples were collected and analyzed for neutrophil:lymphocyte ratio before regrouping at the beginning of the experiment, 24 to 48 h after regrouping, and on the last day of each trial. The use of feeders by individual pigs was assessed by behavioral observations. Average daily gain for the entire 12-wk trial did not differ among group sizes (861, 873, 854, and 845 g/d for groups of 10, 20, 40, and 80, respectively; P > 0.10). During the first 2 wk, ADG was lower for pigs in groups of 40 (554 g/d) than pigs in groups of 10 (632 g/d; P < 0.05), but not pigs in groups of 20 or 80 (602 and 605 g/d, respectively). Average daily feed intake, feed efficiency, and variability in final BW within a pen also did not differ among group sizes. Tail-biting injury scores increased throughout the study, but did not differ among group sizes. Similar proportions of pigs were removed from the trial for health reasons, primarily due to tail biting, in all treatments. Individual pigs in each group size ate from most, if not all, of the feeders in the pen. There was no evidence of spatial subgrouping within the larger groups. The results suggest that housing growing-finishing pigs in groups of up to 80 pigs is not detrimental to productivity and health if space allowance is adequate and feed resources are evenly distributed.

Evaluation of site and age of weaning on pig growth performance.

Site-segregated early weaning (SSEW) refers to the practice of weaning pigs from the sow at an early age and placing them in a nursery that is physically isolated from the breeding herd. An experiment involving 369 pigs was conducted at the Prairie Swine Center to investigate the impact of SSEW on pig performance when the herd of origin has a high health status and when housing and management conditions are kept as similar as possible across weaning regime. Three treatments were compared: weaning at 21+/-3 d and keeping the pigs on-site in an all-in-all-out nursery room (Control), weaning at 12+/-2 d of age and keeping the pigs on-site in a separate but identical all-in-all-out nursery room (OSEW), or weaning at 12+/-2 d of age and moving the pigs off-site to an all-in-all-out nursery room located 16 km from the Center (SSEW). Ventilation, feed, penning, feeders, and drinkers were kept as similar as possible for all treatments. Off-site weaning improved 56-d body weight (P < .05) by 12.5 and 8.3% compared with OSEW and Control, respectively. The improvement appeared to be the result of improvements primarily in feed intake but also due to enhanced efficiency of nutrient utilization. This experiment confirms that SSEW results in significant improvements in 56-d weights, even when the herd of origin has a relatively high health status.

Effects of eating space and availability of water in feeders on productivity and eating behavior of grower/finisher pigs.

Three experiments were conducted to determine the effects of eating space and availability of water within feeders on the productivity and behavior of growing/finishing pigs. In Exp. 1, 12 commercial feeders were classified as being either single-space (SS) or multiple-space (MS), and either as dry (D) or wet/dry (WD), resulting in two SS-D, four MS-D, three SS-WD and three MS-WD models. Each model was evaluated using four pens of 12 pigs, which were fed a mash diet throughout the growing/finishing period (25 to 106 kg). Pigs were videotaped when they were approximately 40 and 80 kg in weight to determine eating behavior. The number of feeding spaces did not affect the productivity of the pigs, but the presence of water within the feeder resulted in increases in ADFI (P < .05) and ADG (P < .05) and a reduction in carcass lean (P < .05). Pigs eating from SS feeders spent 15% less time eating than those fed from two-space feeders (P < .05), and occupancy rate for feeding spaces was increased by 75% (P < .05). The WD feeders also resulted in a reduction (17%) in eatingtime compared to D models (P < .01), and occupancy rate for WD feeders was similarly reduced (P < .05). Pigs spent 16% less time eating when they weighed approximately 80 kg than when they weighed 40 kg (P < .01). In Exp. 2, rate of eating was determined during a short test on the same 12 feeder models for both small (48 kg) and large (90 kg) pigs. Large pigs ate faster than small pigs, but eating rate was not affected by feeding space or presence of water in the feeder. In Exp. 3, eating rate was determined for small amounts of dry or wet feed. Premixing water with the feed (1:1 ratio by weight) increased eating speed (P < .01). We concluded that 12 pigs can be fed from a single-space feeder without affecting productivity. The inclusion of water within a feeder decreases time spent eating, but it increases ADFI and ADG. When pigs are small, they spend more time eating, and feeder occupancy rates are higher than when they are large.

Artificial pigs in space: using artificial intelligence and artificial life techniques to design animal housing.

Computer simulations have been used by us since the early 1970s to gain an understanding of the spacing and movement patterns of confined animals. The work has progressed from the early stages, in which we used randomly positioned points, to current investigations of animats (computer-simulated animals), which show low levels of learning via artificial neural networks. We have determined that 1) pens of equal floor area but of different shape result in different spatial and movement patterns for randomly positioned and moving animats; 2) when group size increases under constant density, freedom of movement approaches an asymptote at approximately six animats; 3) matching the number of animats with the number of corners results in optimal freedom of movement for small groups of animats; and 4) perimeter positioning occurs in groups of animats that maximize their distance to first- and second-nearest neighbors. Recently, we developed animats that move, compete for social dominance, and are motivated to obtain resources (food, resting sites, etc.). We are currently developing an animat that learns its behavior from the spatial and movement data collected on live pigs. The animat model is then used to pretest pen designs, followed by new pig spatial data fed into the animat model, resulting in a new pen design to be tested, and the steps are repeated. We believe that methodologies from artificial-life and artificial intelligence can contribute to the understanding of basic animal behavior principles, as well as to the solving of problems in production agriculture in areas such as animal housing design.

Effects of floor area allowance and group size on the productivity of growing/finishing pigs.

Six group sizes and three levels of floor area allowance were studied in a 6 x 3 factorial arrangement. Group sizes were 3, 5, 6, 7, 10, and 15 pigs per pen. Floor area allowances were .030, .039, and .048 m2 x BW(.667). All pens were square and equipped with a single space feeder and nipple drinker near one corner. Pigs were fed a pelleted diet. Initial weights averaged 25.0 kg, and pigs remained on test for 12 wk. Pigs were weighed, feed intake was determined, and size of pens was increased at 2-wk intervals. Pen size was adjusted to provide the space required for the midpoint of each weigh period. Two replicates of the study were conducted. The ADG was reduced with increasing group size (899, 851, 868, 872, 857, and 821 g, SEM = 16.4, for 3, 5, 6, 7, 10, and 15 pigs, respectively; P < .05), but the CV for gain (mean = .185) did not differ among group sizes. The ADFI also decreased with increasing group size (2.49, 2.34, 2.32, 2.28, 2.28, and 2.21 kg, SEM = .036, for 3, 5, 6, 7, 10, and 15 pigs, respectively; P < .05). Feed efficiency (gain/intake) was highest for group sizes of 7 and 10 pigs (.381) and lowest for pens of three and five pigs (.363; P < .05). The ADG and ADFI (832 g and 2.25 kg, respectively) for the most crowded space allowance were reduced compared to more spacious allowances (ADG and ADFI of 875 and 877 g, and 2.35 and 2.36 kg, for .039 and .048 m2 x BW(.667), respectively; P < .05). Efficiency did not differ among space allowances. These results confirm previous studies reporting a negative effect of increasing group size on productivity, but our study suggests that gain and intake reach a plateau at less space allowance than previously reported.

Preference among cooling systems by gilts under heat stress.

A preference experiment was conducted to compare and evaluate the use of three cooling systems by mature gilts. Systems evaluated were snout coolers (S), drip coolers (D), and conductive cool pads (P). Preference for cooling system and pen position were continuously monitored and evaluated during daily heat stress conditions (34.2 +/- 2.8 degrees C), nightly warm conditions (26.6 +/- 2.3 degrees C), and for total time. The physiological variables of respiration rate (RR) and rectal temperature (Tr) were measured at three separate times daily. Gilts naive to the cooling systems were individually housed in pens with three free stalls, each stall containing a different cooling system. After 1 d of warm temperature (27.6 +/- 2.5 degrees C) acclimation, gilts were exposed to 10 h of the heat stress conditions and 14 h of the warm night conditions each day for six consecutive days. Cooling system use was higher during the hot period (80.2%) than during the warm period (66.2%). The conductive cool pad was preferred over the drip cooler (P < .02) and the snout cooler (P < .0002). The preference for the conductive cool pad persisted in the warm period. Cooling system use had a significant effect on Tr and RR (P < .001). The Tr (P < .005) and RR were lower (P < .005) with the use of the conductive cool pad, whereas the drip cooler and snout cooler showed no effect on these variables.

The effects of regrouping on behavioral and production parameters in finishing swine.

Three trials involving 396 pigs were conducted to determine the effects of regrouping finishing swine (83.8 +/- .69 kg) on weight gain and behavior during the subsequent 2-wk period. The methodology between Trials 1, 2, and 3 differed primarily in the total number of pigs tested (72, 144, and 180, respectively) and the number of pigs per pen (3, 3 or 5, and 5, respectively). In all trials, like-sexed pigs were moved into a new pen location and allotted to one of three treatments: 1) a group of familiar pen mates (Control), 2) a group composed of unfamiliar pigs (Mixed), and 3) pigs mixed with strangers for 24 h and then reunited with original pen mates for the duration of the trial (Mixed 24 h). In the pooled analysis, control pigs gained faster (P < .01) than Mixed pigs (.87 and .77 kg/d, respectively) over the 2-wk period. Mixed 24-h pigs were intermediate in gain (.80 kg/d), indicating that the most severe aggression normally observed during the first 24 h accounts for only a portion of the setback. Apparently the negative social stress associated with being in the presence of unfamiliar pigs persisted beyond the first 24 h and was sufficient to limit weight gain over the 2-wk period. Time spent fighting was reduced from 1.72 min/h during a 6-h period on d 1 to .39 min/h during a 3-h period by d 2 in the Mixed group. Fighting was still observed in the Mixed pens 8 d after regrouping (.23 min/h), indicative of ongoing social conflicts.(ABSTRACT TRUNCATED AT 250 WORDS)

Why the study of animal behavior is associated with the animal welfare issue.

Of the various disciplines within the animal sciences, the issue of animal welfare has been most closely associated with ethology, the study of animal behavior. Prior to the modern welfare movement, applied ethology was primarily involved in studies on feeding and reproductive behavior. The emphasis on freedom of movement and mental experiences in animal welfare resulted in the field of applied ethology developing its current welfare interests. During the past 30 yr, applied ethology has been used to gather appropriate information to develop alternate management systems that accommodate normal behavior. The issue of behavioral needs has been addressed and research interest in motivation has developed. Preference tests have been used for their traditional role of improving comfort and have been modified to assess motivation as well. We have used abnormal behaviors as indicators of poor welfare and are shifting our emphasis to causative factors of these behaviors. The emotional states and cognitive abilities of animals have been studied but will become an increasingly important component of behavior research into animal welfare in the future.