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.

Behaviour and productivity of pigs in groups composed of disproportionate numbers of littermates

Forty litters of eight pigs each were paired by age and weight and re-grouped at the beginning of a 12-wk grower/finisher period. Each pair of litters was assigned to two pens, with two pigs from one litter (Minority) and six pigs from the other (Majority) in each pen. Four pairs of litters were removed from the experiment due to loss of pigs from injury or poor health. Agonistic encounters following re-grouping were used to rank each Minority pig and to classify it as being within the Dominant or Subordinate half of the social hierarchy. Minority pigs within a pen tended to obtain similar social ranks (within two ranks in 20 of 30 pens; P < 0.05), but were as likely to be Dominant as Subordinate (11 vs. 9 pairs, respectively). The activity and position of all pigs were sampled once daily, 5 days a week. One Minority pig was designated as the focal pig for these observations. The second Minority pig was more likely to be engaged in the same activity as the focal pig than were Majority pigs (P < 0.01), and would lie closer to the focal pig than would the Majority pigs (P < 0.01). There were no differences in the proportion of Majority and Minority pigs which were removed from the experiment due to injuries, nor in the type of injuries requiring their removal. Examination of all pigs at the mid-point of the study revealed some evidence of injury on the head, ears, shoulders, back, flanks, ramp and tail of 76, 75, 87, 90, 91 and 95% of the pigs, respectively, but no differences between Majority and Minority pigs in location or severity of injuries. Average daily gain for the entire experiment was 775 g d−1, and did not differ between Majority and Minority pigs during any 2-wk period of the study. It is concluded that littermates continue to associate with each other after re-grouping and that they attain similar social status. However, the litter with the largest number of pigs present does not consistently achieve social dominance or a competitive advantage manifested in improved weight gain. Key words: Pigs, littermates, re-grouping, social status

Behavioral and physiological responses of Meishan, Yorkshire and crossbred gilts to conventional and turn-around gestation stalls

A 5-wk study involving 48 bred gilts was conducted to evaluate behavioral and physiological responses of four geneotypes (Meishan = MM, Yorkshire = YY and crossbred (sire/dam = MY and YM) to two types of gestation stalls (conventional and turn-around). The behavior of gilts was video-recorded on days 0, 7, 21, and 35. Blood samples were taken by venipuncture on days 0, 3, and 36 to determine plasma cortisol haptoglobin, and the neutrophil:lymphocyte (N:L) ratio. A skin-fold thickness response to the mitogen phytohemagglutinin (PHA) was determined on days 1 and 37. Gilts with a Yorkshire sire lay down less often (P < 0.05), spent more time performing chain manipulation (P < 0.05) and drinker manipulation (P < 0.01) and tended to be more active (P < 0.13) than gilts with a Meishan sire. Furthermore, their plasma cortisol levels and N:L ratios were found to be lower (P < 0.01), suggesting genetic differences in adaptive abilities or strategies. Gilts in turn-around stalls stood more frequently, performed more nosing/licking of the stall bars, and more chain manipulation than gilts in conventional stalls (P < 0.05). They also had a lower plasma cortisol level (P < 0.05). The percentage of time spent manipulating the chain increased from day 0 to day 7 (P < 0.05) and then remained constant throughout the experiment. According to our data, providing stalled gilts with the opportunity to turn increases certain activity levels and reduces plasma cortisol level, but does not affect immune system functioning. Key words: Gilts, genotype, gestation stall, behavior, stress

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.

Dietary preferences in early lactation cows as affected by primary tastes and some common feed flavors

A sequential elimination trial was conducted to test the effects of primary tastes on the preference ranking of TMR diets by six multiparous Holstein cows from 8 to 21 DIM. Four additives and a control were examined; the most preferred (highest total intake) was eliminated after segments of 5, 4, 3, and then 2 d. Diets tasting sweet (sucrose, 1.5% of dietary DM), sour (HCl, 1.25%), bitter (urea, 1%), and salty (NaCl, 4%) were tested. Four of the cows most preferred the sweet diet, and DMI of that diet averaged 12.8% more than for the control, which was next preferred. The probability of a diet being chosen first when all diets were presented together was sucrose, .59; control, .36; urea, .04; NaCl, .01; and HCl, .003. Another experiment used the same procedure; however, the additives tested were anise, monosodium glutamate, dehydrated alfalfa meal flavor, and molasses flavor (1.48 g of flavor/kg of DM). Control and monosodium glutamate ranked first equally. The probability of choosing each flavor first in this set was .5 for the control and monosodium glutamate diets and < .01 for molasses, alfalfa, and anise. Rankings were not significantly affected by variation among cows in either experiment. Of the additives tested, only sucrose seemed to have the potential to increase intake.

Behavioral methods to answer questions about sheep

Animal behavior has been defined as the interaction of an animal with its environment. During this interaction the animal must make decisions, based on its evaluation of the environment and its needs, of whether or not the environment is adequate or appropriate for specific behaviors. The environment includes both physical and biotic components, so sheep adjust their behavior in response to such diverse characteristics as the thermal conditions of their environment, the flora present, or the characteristics of other sheep. Although an animal's subjective experiences may not lend themselves to direct evaluation, we may be able to address these questions indirectly by using behavior as an indicator of the animal's decisions. This paper reviews research on the use of space, maternal and neonatal recognition, sexual behavior, and aversiveness. The majority of methods involve preference or acceptance tests. Assumptions, which often affect how tests are conducted and results interpreted, should be made only after the alternatives are carefully considered.

Wood chewing by stabled horses: diurnal pattern and effects of exercise

Nine yearling horses, stabled in individual stalls, were used in a trial to determine the diurnal pattern of wood chewing and the effects of exercise on this behavior. The trial was a Latin square design conducted over three 2-wk periods during which each horse was exposed to each of the three following treatments: 1) no exercise (NE), 2) exercise after the morning feeding (AM), and 3) exercise in the afternoon (PM). Horses were fed a complete pelleted feed in the morning and both pelleted feed and long-stemmed hay in the afternoon. Exercise consisted of 45 min on a mechanical walker followed by 45 min in a paddock with bare soil. Each stall was equipped with two untreated spruce boards during each period for wood chewing. Wood chewing was evaluated by videotaping each horse for 22 h during each period, determining the weight and volume of the boards before and after each period, and by visual appraisal of the boards. Intake of trace mineralized salt was also measured. Wood chewing occurred primarily between 2200 and 1200. All measures of wood chewing were correlated when totals for the entire 6 wk were analyzed. When analysis was performed on 2-wk values, videotape results were not correlated with volume or weight loss of boards. Horses chewed more when on the NE treatment (511 s/d) than when on AM or PM (57 and 136 s/d, respectively; P less than .05). Salt intake tended to be greater for NE than for the other treatments (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)

Attraction of newborn piglets to auditory, visual, olfactory and tactile stimuli

Newborn piglets were removed from their dam and their responses to a variety of sensory stimuli were tested in four experiments. Test stimuli were presented simultaneously in multiple-choice arenas. Piglets allowed to choose among recordings of sow vocalizations, piglet vocalizations or white noise in a 5-min test spent more time in proximity to vocalizations of sows and piglets than near white noise. This was significant for males (P less than .01) but not for females. Piglets choosing among illumination levels (bright, dim or dark) in a 5-min test showed a strong preference for either dim or dark areas over bright light (P less than .01), with no difference between attractivity of dim and dark areas. Piglets choosing among birth fluids, sow's milk or tap water during a 5-min test spent more time with maternal odors than with water (P less than .05). No difference in attractivity between birth fluids and sow's milk was apparent. Preferences of piglets to move either with or against the direction of hair growth were tested using the mid-back area of the sow as a test surface. Piglets moved with the direction of hair growth twice as often as against the growth of hair (P less than .01). Results of these experiments indicate that piglets can discriminate among auditory, olfactory, visual and tactile stimuli immediately after birth.

Effects of sow-crate design on health and performance of sows and piglets

The effects of sow-crate design on certain health and performance traits of 211 sows and their piglets were evaluated with a 2 X 2 X 4 factorial arrangement of crate width (narrow [N = 55 cm] or wide [W = 64] between lowest horizontal pipes), length (short [S = 183 cm] or long [L = 198] from rump stop to front gate) and side type (lower side of sow crate "fingered" [F], "bowed" bottom bar--marking the sow zone 19.3 cm wider at the bottom--20 cm above the floor [B], or straight bottom bar 20 cm [S20] or 25 cm above the floor [S25]). Between d 107 to 110 postcoitum and d 21 postpartum, no crate design variable affected the sow's body-weight change, but side type tended to affect the most prominent head-neck and leg integumentary lesions. Number of stillborn piglets/litter was greater with W crates than with N, except with crates having S20 sides, and was greater with L crates than with S. More piglets were crushed to death in W crates than N crates, and stillbirth frequency was greater in L crates than in S, but overall preweaning piglet mortality was affected by no crate-design feature. At both 7 and 21 d of age, piglets' knee lesions were most severe with S20 crates and least with S25, whereas face-lesion score was unaffected by crate design. Piglet body weight at age 21 d was least with S20 crates and greatest with F and S25. No crate-design variable affected within-litter variation in piglet growth rate. Sow-crate design affected important health and performance traits of piglets through postnatal d 21.

Effects of sow-crate design on sow and piglet behavior

The effects of sow-crate design on certain behaviors of sows and piglets at farrowing and again approximately 3 wk later were evaluated with a 2 x 2 x 4 factorial arrangement of crate width (narrow [N = 55 cm] or wide [W = 64] between lowest horizontal pipes), length (short [S = 183 cm] or long [L = 198] from rump stop to front gate) and side type (lower side of sow crate "fingered" [F], "bowed" bottom bar 20 cm above the floor [B], or straight bottom bar 20 cm [S20] or 25 cm above the floor [S25]). Farrowing-crate design influenced both sow and piglet behaviors both during and immediately after parturition and during nursing-suckling bouts approximately 3 wk later. Activities of 51 sows and their piglets were videorecorded during and immediately following parturition. Sow-crate design affected neither the interval between births of successive piglets in a litter nor the frequency of standing by the sow during parturition. Latency from birth to first mammary contact (LMC) was greater with S25-sided and S sow crates, and especially with S, W crates. A significant interaction occurred between sow-crate side type and dimensions; LMC was longer when S25 sides were combined with S or W crates. Data on suckling behavior were collected from 113 litters over three successive sucklings approximately 3 wk after farrowing. Sow-crate design had no effect either on the consistency with which a piglet suckled a particular teat or teat pair or on the frequency of multiple-teat use. Piglets maintained fewer functional teats with S, S20 crates. The distribution of functional teats between rows was less symmetric with S crates. Piglets nursed with their bodies over a side bar more frequently with B- and S20-sided crates. The sow permitted her piglets to suckle while she was in a vertical stance more frequently with S and N crates, and especially with S, N crates. Sow-crate design affected important behaviors of sows and piglets both during and immediately after parturition as well as during nursing-suckling bouts about 3 wk later.

Effects of amperozide and azaperone on aggression and productivity of growing-finishing pigs

Levels of aggression, activity and performance were determined in 270 pigs (initial wt 29.8 kg) injected with amperozide (1.0 mg/kg i.m.), azaperone (2.2 mg/kg i.m.) or saline (.1 ml/kg i.m.) immediately prior to mixing. Pigs had ad libitum access to feed in pens of 15, and six pens were allotted to each treatment. Each pen was video-taped for 48 h after injection. Aggression was determined by continuous observation and summarized for each 2-h period. Injuries on the ears and shoulders of each pig were scored prior to injection and 1, 2, 3 and 7 d after treatment. Eating, drinking and lying were determined by scan sampling at 2-min intervals and summarized for each 2-h period. Weight gain, feed consumption and efficiency were determined for periods ending on d 3, 7, 14, 28, 42, 56, 70 and 84. Both drugs reduced total fighting from 309.8 min for saline to 190.7 and 189.6 min for amperozide- and azaperone-treated pens, respectively (P less than .01). Treatment differences in aggression and lying were evident during the initial 6 h only. Amperozide resulted in fewer fights involving two pigs (197.3/pen) than did azaperone (260.2/pen) or saline (298.3/pen) (P less than .05). Injuries to the ears (P less than .01) and total injuries (P less than .05) were less severe in amperozide-treated pigs than in pigs on the other treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of creep partitions on teat-seeking behavior of newborn piglets

In the first of two studies on teat-seeking behavior of newborn pigs, latencies from birth to first mammary contact (LMC) and to first suckle (LS) were recorded by live observation (n = 66). LMC accounted for 66% of LS and variances were similar between these two measures, suggesting that LMC is a good predictor of time to first suckle. In a second experiment, 32 litters of pigs were farrowed in crates equipped with either solid, vertically slatted, horizontally slatted or diamond mesh creep partitions. Piglet behavior following parturition was recorded via time-lapse videotape. LMC was determined for each piglet and movements were plotted for four focal pigs/litter. Partition type did not affect LMC (mean = 34 min). LMC was significantly affected by number of littermates present during teat-seeking (P less than .001), birth order (P less than .001) and frequency of position changes by the sow (r = .26, P less than .01). Neither sex nor birth weight affected LMC on a within-litter basis, but across litters smaller pigs had greater contact latencies (r = -.38, P less than .001). Partition type did not affect distance traveled or time spent in contact with the sow, in contact with the creep partitions,, free standing or the total of these. LMC was positively correlated (P less than .05) with contact time with the sow (r = .34) and time behind the sow's back (r = .38) and negatively correlated with time spent free standing (r = -.35, P less than .05) and in contact with the sow's rear legs (r = -.29; P less than .10).

Prepartum behavior of gilts in three farrowing environments

To determine effects of the farrowing environment on prepartum behavior, five gilts were monitored continuously for 48 h prior to parturition in each of three farrowing systems: 1) an open farrowing pen (2.1 x 1.5 m); 2) a turn-around farrowing pen, which allowed the gilt to turn around (2.4 m long; 1.8 m wide at back, .6 at front) and 3) a straight farrowing crate (sow zone = .6 x 2.1 m). Videorecords were summarized as three 16-h segments (Period A = 48 to 32 h before the first piglet was delivered, B = 32 to 16 h and C = 16 to 0 h) for analysis of activity over time. In all systems, frequencies of postural changes and oral-nasal activities directed at the floor or wall increased as farrowing was approached, the highest frequencies occurring in Period C. Respective times spent standing, sitting and engaged in oral-nasal activities directed at floor or wall also increased over time. Pawing occurred almost exclusively in Period C. Lying upright (ventral posture) occupied a greater portion of lying time as the gilt's activity increased over time, whereas feeding and drinking behaviors did not change over time. The only behavior affected by the experimental environments was the frequency of 90 degree turns. Gilts in both open and turn-around pens showed an increasing turning frequency over time, and they turned more often in the open pen than in the turn-around pen.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of birth fluids and cervical stimulation in lamb fostering

Jackets soaked in birth fluids (BF) and cervical stimulation (CS) were used in a 2 X 2 factorial arrangement of treatments to determine their usefulness in fostering lambs. Subjects were 39, 3-d-old to 14-d-old lambs to be adopted by 39, 2-d to 7-d postpartum ewes rearing their own single lambs. Birth fluids were collected by drying newborn lambs with cloth jackets. Jackets were frozen for storage and were later thawed and placed on experimental alien lambs. Cervical stimulation was applied by attempting to insert a hand into the cervix of the ewe for 5 min immediately before presentation of an alien lamb. Maternal behavior tests, in both the absence and presence of the ewe's own lamb, were conducted twice daily in a small pen for 2.5 d. On d 3 and 4, lambs were tested in a large pen with three to four other ewes and their lambs. Aggression toward the alien lamb was greater during the first exposure in all treatments. Avoidance and nosing behaviors toward aliens were significantly less, and alien lambs were able to suckle more, when the ewe's own lamb was also present. Lambs receiving BF suckled more and were accepted more often. Cervical stimulation, in the absence of BF, improved acceptance compared with controls. The proportion of ewes accepting alien lambs were 100, 80, 60 and 10% for BF, BF-CS, CS and control treatments, respectively. Alien lambs that were accepted had similar growth rates to weaning as the ewe's own lamb. We conclude that fostering is facilitated by use of jackets soaked in BF and by CS.

Effects of auditory, visual and chemical stimuli on the ingestive behavior of newly weaned piglets

Auditory, chemical and visual stimuli were used in a factorial trial in an attempt to stimulate feeding in newly weaned piglets. Ninety-six crossbred piglets weaned at 28 d of age were assigned to groups containing four littermates. Each group was placed in a 1.2-m X 1.2-m pen in an isolated room for 48 h. Pens were equipped with nipple waterers and trough-type feeders. The auditory stimulus was piglet and sow nursing vocalizations. A visual stimulus was provided by a lamp that illuminated the feeding area. Auditory and visual stimuli were presented for 5 min once an hour for 48 h. The chemical stimulus consisted of 60 ml of evaporated milk sprayed over the surface of the feed once every 12 h. Water was used in place of milk in control treatments. Piglets were videotaped for 48 h. Frequency and duration of feeding, drinking and lying were recorded for two piglets out of each pen. Auditory stimuli increased (P less than .05) the number of drinking bouts per day from 16.3 to 19.2 and the number of drinking bouts associated with stimulus presentation from 6.2 to 8.0. There also was an auditory X day interaction effect on total time spent feeding. On d 2 postweaning piglets in the auditory treatment group spent more (P less than .05) time feeding than did those without auditory stimulation (127.1 vs 104.2 min, respectively). The relatively simple visual and chemical stimuli tested had no significant effects on ingestive behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Maternal and neonatal behavior

Maternal and neonatal behavior differs among food-producing mammals, and our management must reflect these differences. Sows will show more elaborate preparturient behavior than the other species as they attempt to build a nest that will last for several days. Because the nest is the focal point of maternal behavior for several days, the sow does not need to recognize her piglets until they are about 1 week of age. Although this facilitates the fostering of piglets between litters, the teat order developed by piglets during the first day or two makes it difficult for alien piglets to suckle when first fostered. Piglets are weaned at a relatively early age, and this results in conflict as neonatal behavior persists in an environment that requires better developed feeding patterns. Restrictions placed on ewes and cows by confinement at the time of parturition may result in their being unable to select an appropriate birth site. Our management must accommodate these needs by providing sites that are protected from the harsh environment and also allow separation from the rest of the flock. This is particularly important for ewes bearing multiple young, for lambs frequently become separated from the ewe while she is caring for another lamb. Both cows and ewes must be allowed to bond to their offspring soon after birth if they are to provide adequate maternal care. Fostering in these species involves manipulation of identifying stimuli to overcome the dam's ability to recognize her own young shortly after birth. Suckling problems, due to pendulous udders on cows and multiple lambs in sheep, may require attention by the stockman shortly after birth. Weaning does not result in major behavioral problems in sheep or beef cattle that are weaned after the young are consuming solid feed on a regular basis. Dairy calves, which are initially weaned onto milk replacer at a very early age, may develop inappropriate sucking behaviors that persist beyond weaning onto a solid diet. Despite our growing knowledge of maternal and neonatal behavior, mortality among piglets, lambs, and calves is still high. However, many of the most recent findings have yet to be incorporated into management procedures or standard practice. As this occurs, we should be able to reduce losses of young animals.

Effect of excess levels of methionine, tryptophan, arginine, lysine or threonine on growth and dietary choice in the pig

Six experiments were conducted with newly weaned pigs (8 kg) to evaluate the effects of 4% excesses of DL-methionine, L-tryptophan, L-threonine, L-lysine or L-arginine on growth or "choice" (i.e., self-selection) when added to 20% protein, corn-soybean meal (C-SBM) diets. Arginine was supplied as the free base and lysine as lysine acetate to avoid acid-base problems. In the growth study, gain was reduced 52, 31, 28, 16 and 5% by additions of methionine, arginine, tryptophan, lysine and threonine, respectively. Small decreases in gain/feed occurred in pigs fed diets with excess methionine or lysine. Feed intake depressions were evident in pigs fed excess methionine or excess tryptophan within 1 d after initiation of the growth trial. Self-selection studies revealed that pigs strongly preferred the control diet over any of the diets containing excess amino acids. Further studies indicated that pigs preferred diets with excess threonine, lysine or arginine over those containing an equal excess (i.e., 4%) of methionine or tryptophan. Moreover, there was a tendency for pigs to prefer the diet with excess threonine over the one containing excess lysine or arginine. Also, pigs clearly preferred the diet with excess methionine over the diet containing excess tryptophan. When given a choice between a protein-free diet and a C-SBM diet containing 4% excess tryptophan, pigs initially (d 0 to 4) preferred the protein-free diet, but later adapted to the extent that during the last 4 d of the 12-d trial they consumed more of the tryptophan-imbalanced diet than of the protein-free diet.

Changes in serum cortisol reveal functional differences in frustration-induced chain chewing in pigs

The pituitary-adrenal correlates of oral stereotypes in pigs were studied in two frustration situations of intermittent food distribution in which small amounts of food were given every 4 min (n = 4), and a massed food situation in which the same total amount of food was given in one meal at the beginning of the session (n = 5). Control animals (n = 6) were exposed to intermittent food but without a chain. Both intermittent-food and massed-food pigs developed chain chewing at similarly high rates. Blood samples were taken on days 8 and 21 of the experiment. Serum cortisol decreased between the beginning and the end of session 21 in intermittent-food pigs, but increased in pigs subjected to the massed-food condition. These findings suggest that oral stereotypies elicited by an intermittent schedule of food presentation are not equivalent to those elicited by the massed-food regimen.

Assessment of comfort and well-being in farm animals

The assessment of comfort and well-being in farm animals is discussed in terms of physical damage, physiological responses and behavior. Injuries may be due to the physical environment or contact, such as aggression, with other animals. Animals may reduce the frequency of injuries by modifying their behavior. Evaluation of injuries requires a methodical assessment of specific areas of the body and examination of the facilities and behavior of the animal to determine cause. The physiological response of an animal is dependent upon its psychological response. The adrenal medullary and cortical responses represent distinct strategies that may occur simultaneously or independently of each other. Stress frequently results in suppression of immune responses, although some aspects of the immune system are enhanced. Inadequate or excessive motivation results in behavioral problems and facilities must accommodate the behavior of the animals. Methods of preference-testing have been improved to evaluate factors in the environment and assess motivation for specific behaviors more reliably. All of the methods used to assess comfort and well-being must consider the animal's ability to adapt to different environments. Although it remains difficult to assess comfort and well-being across systems, improvement within a system can be demonstrated.

Effects of zeranol implantation and late castration on sexual, agonistic and handling behavior in male feedlot cattle

Seventy-two Angus feedlot bulls were observed to determine the effects of implanting with zeranol (0, 36 or 72 mg; four groups of six/level) at 8 mo of age (d 0), and of castration midway through the feedlot period (d 115) vs remaining intact (six groups/treatment) on sexual, agonistic and handling behaviors. All 36-mg-treated cattle were re-implanted (36 mg) on d 112; 72-mg-treated cattle were not re-implanted. Each group was observed for a total of 8 h at the time of sunset +/- 30 min for sexual and agonistic behaviors during the trial. Observations on handling were made during 15 weighings and on seven occasions in the pens of the animals. Zeranol did not affect sexual or agonistic behavior. Before imposition of castration, implanted bulls entered the scales more quickly, took longer to stand still on the scales and were less quiet than non-implanted bulls (P less than .05). Castration decreased the sexual behaviors of masturbation (.75 vs .08 X pen-1 X h-1; P less than .05), attempted mounts (.75 vs .33 X pen-1 X h-1; P less than .05) and chinning (10.70 vs 4.75 X pen-1 X pen-1; P less than .10) and the agonistic behavior of butting (42.42 vs 31.50 X pen-1 X h-1; P less than .01) in contrast to intact bulls. Castrated animals entered (P less than .10) and exited (P less than .05) the scales more quickly than did intact males.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of zeranol implants on growth, behavior and carcass traits in Angus and Limousin bulls and steers

A 2(3) factorial arrangement of treatments was utilized to determine effects of postweaning zeranol implantation, breed (Angus vs Limousin) and castration (bull vs steer) on growth, behavior and carcass traits. An initial slaughter group was used to account for breed differences in composition and to determine fat and lean growth in the 9-10-11th rib section (NTE). The remaining cattle were fed a finishing diet to a fat end point of .76 cm, as determined by a backfat probe. Control bulls outgained (P less than .01) control steers both to the first kill date and over the entire test and did not require significantly more time to reach the fat end point. The implant did not influence gain in bulls but did increase gain in steers. Angus and Limousins were similar in growth rate for the first 126 d before the first slaughter date. Limousins required more (P less than .01) time to reach the fat end point. Bulls and Limousins produced heavier (P less than .01) carcasses and larger rib eyes (P less than .05; bulls; P less than .01; Limousins). Steers and Angus had higher (P less than .01) marbling scores and lower bone maturity. Implanting decreased (P less than .05) marbling and increased carcass maturity. Small but significant shifts in carcass wholesale cut weight distribution were found between breed and sex condition groups. Bulls and Limousins had greater lean growth in the NTE. Bulls and steers were similar in fat growth, but Angus exceeded Limousin in this trait. Zeranol reduced scrotal circumference (P less than .01) and testicle weight at slaughter (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of double decking and space allowance on the performance and behavior of feeder lambs

A 2 X 2 factorial experiment was conducted using growing lambs to compare single-level vs double-decked pens and high (.32 m2/lamb) vs low (.48 m2/lamb) densities. Three replicates of each treatment combination were involved using 30 lambs/pen. In the double-decked pens, an upper deck located over the rear section of the lower level provided one-third of the total floor area. Feed and water were provided on the lower level only and lambs could move freely between levels by means of a slatted ramp. All floors were of expanded metal. Use of the various areas of the pens was determined during a 24-h observation and by a videotape recording of the double-decked pens during the daylight hours. Fleece contamination was determined by visual observation and standard wool testing procedures. Gain was determined over the 8-wk period of each replicate. The high density treatment resulted in 1.5 kg/lamb (10%) less gain (P less than .01) and, in the case of double-decked pens, different patterns of space utilization compared with the low density treatment. Lambs in the low density pens were able to move more successfully from resting areas to the feeding area in the afternoon (P less than .01). The double-decked system did not significantly affect weight gain, but resulted in dirtier fleeces (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)