Board-invited review: Using behavior to predict and identify ill health in animals

We review recent research in one of the oldest and most important applications of ethology: evaluating animal health. Traditionally, such evaluations have been based on subjective assessments of debilitative signs; animals are judged ill when they appear depressed or off feed. Such assessments are prone to error but can be dramatically improved with training using well-defined clinical criteria. The availability of new technology to automatically record behaviors allows for increased use of objective measures; automated measures of feeding behavior and intake are increasingly available in commercial agriculture, and recent work has shown these to be valuable indicators of illness. Research has also identified behaviors indicative of risk of disease or injury. For example, the time spent standing on wet, concrete surfaces can be used to predict susceptibility to hoof injuries in dairy cattle, and time spent nuzzling the udder of the sow can predict the risk of crushing in piglets. One conceptual advance has been to view decreased exploration, feeding, social, sexual, and other behaviors as a coordinated response that helps afflicted individuals recover from illness. We argue that the sickness behaviors most likely to decline are those that provide longer-term fitness benefits (such as play), as animals divert resources to those functions of critical short-term value such as maintaining body temperature. We urge future research assessing the strength of motivation to express sickness behaviors, allowing for quantitative estimates of how sick an animal feels. Finally, we call for new theoretical and empirical work on behaviors that may act to signal health status, including behaviors that have evolved as honest (i.e., reliable) signals of condition for offspring-parent, inter- and intra-sexual, and predator-prey communication.

Technical note: validation of a system for monitoring individual feeding and drinking behavior and intake in group-housed cattle

The objective of this study was to validate a system for monitoring individual feeding and drinking behavior and intake in group-housed cattle. A total of 42 Holstein cows were tested with access to 24 feed bins and 4 water bins. For the purposes of this validation experiment, we focused our observations on 4 water bins and 13 feed bins. When the cow approached the feed or water bin, an antenna detected the cow's unique passive transponder and lowered the barrier, allowing the cow access to the feed or water. For each visit to the bin, the system recorded the cow number, bin number, initial and final times and weight and calculated the visit duration and intake. Bins were also monitored by direct observation and time-lapse video recording for 2 d per bin, with observations for 4 and 6 h/d for the feed and water bins, respectively. Data from direct observations were compared with the electronic data recorded by the system. Feed disappearance over 24 h was assessed by using an external scale over 3 consecutive 24-h periods, and these values were compared with the sum of intakes across all visits to that bin for the same time periods. The system showed a high specificity (100%) and sensitivity (100 and 99.76% for the feed and water bins, respectively) for cow identification. The duration of the feeding and drinking visits and the feed and water intake per visit, as estimated by the monitoring system, were highly correlated with those obtained by direct observation (R(2) >/= 0.99 in all the cases). The comparison of the total feed that disappeared from each bin in 24 h with the sum of the feed cows consumed from that bin during the same period differed by less than 1 kg (29.92 +/- 0.90 kg and 29.24 +/- 0.90 kg as estimated by manual weighing and by the electronic system, respectively). This difference could be attributed to changes in feed moisture during the 24-h period. In conclusion, this electronic system is a useful tool for monitoring intakes and feeding and drinking behavior of loose-housed cows.

Effects of bedding quality on lying behavior of dairy cows

Cows prefer to spend more time lying down in free stalls with more bedding, but no research to date has addressed the effects of bedding quality. Bedding in stalls often becomes wet either from exposure to the elements or from feces and urine. The aim of this study was to test the effect of wet bedding on stall preference and use. Four groups of 6 nonlactating Holstein cows were housed in free stalls bedded daily with approximately 0.1 m of fresh sawdust. Following a 5-d adaptation period, each group of cows was tested sequentially with access to stalls with either dry or wet sawdust bedding (86.4 +/- 2.1 vs. 26.5 +/- 2.1% dry matter), each for 2 d. These no-choice phases were followed by a 2-d free-choice phase during which cows had simultaneous access to stalls containing either wet or dry bedding. Stall usage was assessed by using 24-h video recordings scanned at 10-min intervals, and responses were analyzed by using a mixed model, with group (n = 4) as the observational unit. The minimum and maximum environmental temperatures during the experiment were 3.4 +/- 2.2 and 6.8 +/- 2.5 degrees C, respectively. When cows had access only to stalls with wet bedding, they spent 8.8 +/- 0.8 h/d lying down, which increased to 13.8 +/- 0.8 h/d when stalls with dry bedding were provided. Cows spent more time standing with their front 2 hooves in the stall when provided with wet vs. dry bedding (92 +/- 10 vs. 32 +/- 10 min/d). During the free-choice phase, all cows spent more time lying down in the dry stalls, spending 12.5 +/- 0.3 h/d in the dry stalls vs. 0.9 +/- 0.3 h/ d in stalls with wet bedding. In conclusion, dairy cows show a clear preference for a dry lying surface, and they spend much more time standing outside the stall when only wet bedding is available.

Overstocking Reduces Lying Time in Dairy Cows

Our objective was to understand the effect of overstocking on the lying and standing behavior of dairy cattle. We manipulated freestall availability by providing 12, 11, 10, 9, or 8 freestalls to 12 cows (n = 4 groups, 12 cows/group), thus creating stocking levels of 100, 109, 120, 133, and 150%, respectively. Treatments were applied for a week at a time in a switchback design. Each group returned to the 100% stocking level after exposure to the other treatments. In addition to lying and standing behavior, we measured each cow's ability to displace others from the freestall to understand the interaction between social status and response to overstocking. When groups of cows had fewer stalls available, they spent less time lying down. There was no effect of overstocking on time spent standing with only the front legs in the stall. Instead, cows compensated for the reduced lying times by spending more time outside of the stall. When fewer stalls were available, animals were more likely to be displaced from stalls. The cow's ability to displace others from the stalls, however, did not explain the magnitude of their reduction in lying time when provided with fewer freestalls. Due to increased competition for stalls, cows lay down sooner at 150% than at the 100% level. Stall use was more uniform across time and across stalls within the pen when fewer freestalls were available. In conclusion, when cows had access to fewer freestalls, there was increased competition for stalls, increased time standing outside the stalls, and reduced lying time.

Prepartum Behavior and Dry Matter Intake Identify Dairy Cows at Risk for Metritis

Metritis is a disease of particular concern after calving because of its profound negative effects on the reproductive performance of dairy cows. Cows at risk for metritis have shorter feeding times in the days before calving but prepartum dry matter intake (DMI) and water intake may also be useful in identifying cows at risk for this disease. Feeding, drinking, and intake measures may also be affected by social interactions among group-housed cows. The objective of this study, therefore, was to measure intake, feeding, drinking, and social behavior to determine which measures could identify cows at risk for metritis after calving. Feeding and drinking behavior and intake measures were collected from 101 Holstein dairy cows from 2 wk before until 3 wk after calving using an electronic monitoring system. Social behavior at the feed bunk was assessed from video recordings. Metritis severity was diagnosed based on daily rectal body temperature as well as condition of vaginal discharge that was assessed every 3 d after calving until d +21. In this study, 12% of cows were classified as severely metritic and 27% as mildly metritic. Prepartum feeding time and DMI were best able to identify cows at risk for metritis. Cows that developed severe metritis spent less time feeding and consumed less feed compared with healthy cows beginning 2 wk before the observation of clinical signs of infection. For every 10-min decrease in average daily feeding time during the week before calving, the odds of severe metritis increased by 1.72, and for every 1-kg decrease in DMI during this period, cows were nearly 3 times more likely to be diagnosed with this disorder. During the week before calving, cows that were later diagnosed with severe metritis had lower DMI and feeding times during the hours following fresh feed delivery. During this period these cows also engaged in fewer aggressive interactions at the feed bins compared with cows that remained healthy. This research is the first to show that social behavior may play an important role in transition cow health. Research is now required to determine how management should be changed to reduce or prevent illness in transition dairy cows.

Maternal behavior in cattle

We provide a critical summary of the literature on maternal behavior in cattle. The studies we review increase our basic understanding of this behavior and provide insights into practical problems in cattle production. When domesticated cattle are permitted to rear their young, the behaviors associated with maternal care are for the most part similar to those observed in wild ungulates. These behaviors allow the cow to bond with her calf, protect and provide it with nourishment and ultimately break down this bond at weaning. Different commercial production systems have emphasized different maternal behaviors, some being viewed as advantageous while others are considered a hindrance. Extensive production systems (most beef cattle production) place the responsibility of rearing the newborn largely on the cow and risk factors that affect the maternal bonding process (e.g. cross licking) remain important practical challenges. Most dairy cattle production discourages all aspects of maternal behavior with the exception of milk production, but changing consumer demand (e.g. increases in organic production) will make an understanding of maternal behavior in this system a priority in years to come.

Softer, Higher-Friction Flooring Improves Gait of Cows With and Without Sole Ulcers

We studied dairy cows (n = 30) walking on concrete and on a soft, high-friction composite rubber surface to examine how flooring influenced gait and how this differed for cows with hoof lesions. Cows had hooves trimmed 9 wk after the trial and were classified as either with or without sole ulcers. Video recordings of the cows while walking were digitized using motion analysis software to calculate stride variables (length, height, overlap, duration, proportion of triple support, and speed). Gait was scored by a subjective scoring system (1 = sound to 5 = severely lame) and by a continuous visual analog scale for each of 7 gait attributes. Cows with sole ulcers walking on a composite rubber surface had longer strides (156.9 +/- 2.6 vs. 149.6 +/- 2.6 cm), higher stride heights (9.7 +/- 0.3 vs. 8.8 +/- 0.3 cm), more stride overlap (0.4 +/- 2.0 vs. -4.3 +/- 2.0 cm), shorter periods of triple support (3 legs in ground contact; 68.6 +/- 2.0 vs. 73.8 +/- 2.0%), walked faster (1.22 +/- 0.04 vs. 1.17 +/- 0.04 m/s) and had lower overall gait scores (2.9 +/- 0.1 vs. 3.1 +/- 0.1), better tracking-up (19 +/- 2 vs. 24 +/- 2), better joint flexion (29 +/- 2 vs. 33 +/- 2), more symmetric steps (31 +/- 3 vs. 36 +/- 3), and less reluctance to bear weight on their legs (12 +/- 2 vs. 16 +/- 2) compared with walking on concrete. Similar results were found for cows without sole ulcers. Most of the subjective gait measures could distinguish between cows with and without sole ulcers, but this was not the case for kinematic measures other than stride height. Cows with higher gait scores (more severe lameness) showed the greatest improvement in stride length (r = -0.51), triple support (r = 0.59), swing duration (r = -0.44), overall gait score (r = 0.46), and reluctance to bear weight (r = 0.66) when walking on the rubber surface compared with cows with lower gait scores. These results indicate that rubber flooring provides a more secure footing and is more comfortable to walk on, especially for lame cattle.

Effects of Pasture on Lameness in Dairy Cows

This study tested whether providing cows a 4-wk period on pasture would improve gait and change lying behavior. Eighteen groups, each of 4 lactating Holstein cows initially housed in a freestall barn, were assigned to either continued housing in the same freestall barn, or moved to pasture to provide changes in both physical environment and diet. To assess lameness, gait scores (1 to 5) were recorded weekly for 4 wk. Gait improved by an average of 0.22 units/wk for those cows kept on pasture. We also recorded 4 specific gait attributes (head bob, back arch, tracking up, and reluctance to bear weight evenly on all 4 hooves), and found that the latter 2 attributes also improved during the pasture period. Improved gait for cows on pasture was not because of increased lying times. Cows on pasture actually spent less time lying down than cows kept indoors (10.9 vs. 12.3 h/d), although this lying time was spread over a larger number of bouts (15.3 vs. 12.2 bouts). Cows housed on pasture also lost more weight and produced less milk relative to cows in freestalls, likely because of reduced nutrient intake. These results indicate that a period on pasture can be used to help lame cattle recover probably because pasture provides a more comfortable surface upon which cows stand, helping them to recover from hoof and leg injuries.

Effects of continuous versus periodic milk availability on behavior and performance of dairy calves

Dairy calves fed milk ad libitum engage in feeding activity throughout the day and night. However, providing calves with continuous access to milk can present practical problems with milk quality, particularly during warm weather. One way to maintain milk quality in ad libitum feeding regimens is to limit the time that milk is available, but no research to date has addressed how this might affect calves. The objectives of this study were to quantify the effects of continuous access to milk (24 h/d) vs. access during only part of the day on milk feeding behavior and performance. Twenty-eight female Holstein calves were randomly assigned to treatments at 5 +/- 3 d of age and monitored for 28 d. All calves had milk delivered through a teat. Treatments were 1) access to milk for 24 h/d; 2) access to milk for 2 feedings per day (each of 2 h), with water available through the teat the remainder of the day (4-h wet treatment); and, 3) access to milk for 2 feedings per day (each of 2 h), but with no water available through the teat (4-h dry treatment). Calves given 24-h access to milk consumed 11.2 +/- 0.5 kg/d on average. Milk intake tended to be lower for the 4-h wet and 4-h dry treatments, averaging 10.0 +/- 0.3 kg/d, with no difference between these 2 treatments in this or any other variable. Average daily gain over the course of the experiment did not vary with treatment and averaged 1.1 +/- 0.04 kg/d. Calves in the 24-h treatment spent more time on the teat than those calves on the 4-h treatments, but during the 4 h/d when milk was available to all calves, calves in the 4-h treatments spent more time on the teat. These results show that individually housed calves fed milk ad libitum for only 4 h/d compensate by changing their milk feeding behavior and are able to achieve similar weight gains to animals fed milk continuously.

Brisket Boards Reduce Freestall Use

We examined how the presence of a brisket board influenced cow preference, stall use, and position within the stall. When given a choice between stalls with or without a brisket board, 15 nonlactating cows spent 68% of their time lying in the stalls without a brisket board, indicating that they preferred this option. When 13 cows had access to either stalls with a brisket board or ones without, they spent, on average, 1.2 h/d more time lying down in stalls without a brisket board. Resting cows positioned themselves relatively forward in the stalls in 98 +/- 5% (mean +/- SE) of lying bouts when the brisket board was absent, compared with 67 +/- 5% of bouts when the board was present. Longer cows were more likely than shorter cows to move forward in the stalls without a brisket board. Cows also had longer lying bouts in stalls without the brisket board (absent: 1.7 +/- 0.08; present: 1.5 +/- 0.08 h/bout). Although it seems likely that the brisket board helps keep stalls clean by positioning cows closer to the curb, our results indicate that brisket boards also make stalls less comfortable for cows. Stall features designed to reduce stall maintenance may compromise cow comfort. We suggest that new approaches to cow housing are now required.

Hoof Discomfort Changes How Dairy Cattle Distribute Their Body Weight

Lameness is a costly and widespread health and welfare problem in intensive dairy production, and reliable automated methods to detect lameness are needed. Lameness may be detected through the measurement of how cattle distribute their weight among their 4 legs, but this requires an understanding of how cattle redistribute their weight in response to pain in one or more limbs. In 3 experiments, 13, 12, and 15 Holstein dairy cows were trained to stand on a platform that measured the weight placed on each limb. We replaced the soft rubber surface under either 1 or 2 hooves with an uncomfortable concrete surface. Cows placed less weight on a back hoof that was placed on an uncomfortable surface, and they redistributed the majority of the weight onto the contralateral back hoof but did not change the distribution of weight on their front hooves. When the same surface was placed under a front hoof, cows placed less weight on that hoof and placed more weight on the contralateral front hoof and the ipsilateral back hoof. The variation in weight the cow placed on both contralateral hooves increased when one of the hooves was on the uncomfortable surface. Cows placed more weight on the back hooves when both front hooves were standing on uncomfortable surfaces, although no change was observed when back hooves were on uncomfortable surfaces. Dairy cows remove weight from a limb in response to limb discomfort and redistribute this weight primarily to the contralateral limb. The variation in weight over time applied to a pair of contralateral limbs increases in response to discomfort in one hoof. Cows have only limited ability to shift weight from front to back. Measures of weight distribution may provide useful on-farm techniques for the detection of lameness.

Flooring in Front of the Feed Bunk Affects Feeding Behavior and Use of Freestalls by Dairy Cows

In 2 experiments we assessed how preferences, time budgets, and feeding behavior of dairy cows change in response to flooring surfaces in front of the feed bunk. In Experiment 1, 12 nonlactating dairy cattle were individually housed with access to 2 standing platforms filled with either concrete or sawdust. In Experiment 2, 24 nonlactating dairy cattle were given access to either concrete or Animat rubber flooring in front of the feed bunk. In Experiment 1, cows preferred the sawdust to the concrete flooring. In both experiments, cows provided with a softer floor in front of the feed bunk spent more time standing near the feed bunk without eating (Experiment 1: 67 vs. 40 min/d on sawdust vs. concrete, respectively, SEM = 5.6 min/d; Experiment 2: 176 vs. 115 min/d on Animat vs. concrete, respectively, SEM = 20.5 min/d) compared with when they were kept on concrete. The increased time spent at the feed bunk was due to a combination of more frequent eating and standing bouts, indicating that cows were more willing to move on nonconcrete flooring. Total time spent eating was significantly greater on the softer floor in Experiment 2, but not in Experiment 1 (Exp. 1: 289 vs. 275 min/d on sawdust and concrete, respectively, SEM = 7.3 min/d; Exp. 2: 330 vs. 289 min/d on Animat and concrete, respectively, SEM = 15.4), although feed intake was increased on the sawdust treatment in Experiment 1. Cows spent significantly more time lying in the feed alley when the flooring was rubber (219 vs. 53 min/d on Animat and concrete, SEM = 53.6 min/d), perhaps because the lying area in Experiment 2 was inadequate. In conclusion, cows prefer to stand on softer flooring in front of the feed bunk, and are more willing to move on and spend more time standing in front of the feed bunk when provided with softer flooring. These results indicate that cows find softer flooring surfaces more comfortable to stand on than concrete, and highlight the importance of evaluating the comfort of the entire facility.

Effects of Milking on Dairy Cow Gait

We studied cows with (n = 6) and without (n = 26) sole ulcers before and after milking to explore how milking influences dairy cattle gait and how this differs for cows with hoof injuries. Video recordings of cows were digitized using motion-analysis software to calculate stride variables for each hoof. Gait was scored using a 1-to-5 numerical rating system (1 = sound, 5 = severely lame) and a continuous 100-unit visual analog scale of gait attributes (back arch, head bob, tracking-up, and reluctance to bear weight). For cows with and without sole ulcers, differences in gait before and after milking were evident; after milking, all cows had significantly longer strides (123.3 vs. 133.5 +/- 2.0 cm, respectively), higher stride height (8.3 vs. 8.9 +/- 0.1 cm), shorter stride durations (1.49 vs. 1.41 +/- 0.03 s), walked faster (0.85 vs. 0.97 +/- 0.03 m/s), and had shorter periods of triple support (3 legs in ground contact; 80.0 vs. 71.7 +/- 2.0%). Tracking-up and reluctance to bear weight improved after milking (20 vs. 16 +/- 2; 20 vs. 15 +/- 1, respectively), but numerical rating scores and back arch did not. Cows with sole ulcers walked differently than cows without for all measures, except swing duration, both before and after milking. Interactions between hoof health and milking were found for swing duration and head bob but when tested separately, the only effect was that cows without sole ulcers had longer swing durations before milking (0.45 vs. 0.44 +/- 0.01 s, respectively). Gait differences were probably due to udder distention and motivation to return to the home pen. Our results suggest that the most suitable time to assess lameness is after milking when differences between cows with and without ulcers are most evident.

Differential effects of sodium and magnesium sulfate on water consumption by beef cattle1,2

The existing guidelines for maximum sulfate (SO4) in cattle drinking water are based on Na2SO4, although many water sources contain greater concentrations of MgSO4. Two experiments compared the effect of different SO4 salts on water consumption and fecal DM of cattle. In Exp. 1, 8 yearling heifers (initial BW = 345 +/- 8 kg; mean +/- SD) were watered twice daily with tapwater or water containing Na2SO4 or MgSO4 at target levels of 1,500, 3,000, or 4,500 mg of SO4/L for 2-d treatment periods separated by 2 d of access to tapwater. In Exp. 2, 16 yearling cattle (initial BW = 421 +/- 24 kg) were watered twice daily with tap-water (16 mg of SO4/L) or water containing Na2SO4 at target levels of 2,000 mg of SO4/L (low Na2SO4), MgSO4 at 2,000 mg of SO4/L (low MgSO4), or MgSO4 at 4,000 mg of SO4/L (high MgSO4) in 21-d treatment periods separated by 7-d periods on tapwater. The first 10 d of each period were allowed for adjustment to the treatment, and the final 11 d was considered the treatment period for analysis purposes. Treatments were applied in an incomplete Latin square, where each animal was exposed to 3 of the 4 treatments. In Exp. 1, the average daily water consumption decreased linearly as the SO4 concentration increased for MgSO4 (P = 0.0001) but not for Na2SO4 (P = 0.39). In Exp. 2, the average daily water consumption was less for cattle on the high-MgSO4 treatment than for cattle on the low-MgSO4 treatment (P = 0.0001), and cattle on the low-MgSO4 treatment tended (P = 0.09) to drink less than those on the tap-water treatment. Fecal DM was greater for cattle on the high-MgSO4 treatment than for those on the low-MgSO4 treatment (P < 0.01). These findings indicate that cattle reduce their consumption of water containing high (> or = 4,000 mg of SO4/L) concentrations of MgSO4, even after a given time to adjust to the treatment; such reductions may be accompanied by an increase in fecal DM.

Effects of mixing on drinking and competitive behavior of dairy calves

Group housing provides increased access to space and social interactions for calves while reducing labor costs for producers. However, group housing necessarily requires that calves be mixed and no research to date has addressed the effects of mixing on behavior of milk-fed dairy calves. The objective of this study was to monitor the feeding and competitive behavior of individual dairy calves (n = 8) after introduction into an established group of older calves fed ad libitum by a computer-controlled milk feeder. Milk feeding was monitored for 2 d before introduction into the new group and both milk feeding and competitive behaviors were monitored for 4 d after mixing. Mean (+/- SE) milk consumption before mixing was 9.7 +/- 0.7 kg/d, dropped slightly on the day of mixing to 8.6 +/- 0.6 kg/d, but increased on d 1 to 3 after mixing to 11.1 +/- 0.3 kg/d. Calves visited the feeder less frequently on the day of mixing (6.0 +/- 1.8 visits/d) than on either the days before mixing (20.3 +/- 2.5 visits/d) or the days after mixing (25.3 +/- 6.9 visits/ d). The mean duration of feeder visits and mean milk consumption per visit increased from 4 min 15 s +/- 21 s and 0.53 +/- 0.06 kg per visit before mixing to 8 min 17 s +/- 1 min 28 s and 1.87 +/- 0.51 kg per visit on the day of mixing. Competitive displacements from the milk-feeding stall were rare. In summary, feeding behavior of young calves is altered on the day of mixing, but calves are able to maintain milk intake when using a milk feeder fitted with a stall that prevents calves from displacing one another.

Feeding behavior identifies dairy cows at risk for metritis

Dairy cows experience a high incidence of disease and metabolic disorders in the weeks immediately following calving, but early and accurate diagnosis remains a challenge. Cows suffering from metritis, one common disease following calving, exhibit reduced milk yield and reproductive performance. However, afflicted cows show few overt signs of illness and frequently go unnoticed in the absence of veterinary examination. To determine whether changes in feeding behavior could be used to identify animals at risk for metritis, attendance at the feed alley was monitored continuously for 26 Holstein cows during the transition period, beginning 2 wk before and ending 3 wk after calving. Every 3 +/- 1 d, cows were examined for metritis based on rectal body temperature and condition of vaginal discharge. Over the 3 wk of observations after calving, 69% of cows showed some signs of metritis. These cows spent on average 22 min/d less time at the feed alley during the transition period than did non-metritic cows. For every 10-min decrease in average daily feeding time, cows were twice as likely to be diagnosed with metritis. A threshold of 75 min of average daily feeding time was 89% sensitive and 62% specific for detection of acute metritis. In conclusion, reduced time at the feeder can be used to identify dairy cows at risk for metritis. More research is required to determine how soon before calving at-risk cows can be identified and whether these behavioral differences can also be used in the early diagnosis of other diseases or metabolic disorders.

Hoof pathologies influence kinematic measures of dairy cow gait

To explore how hoof pathologies affect the gait of dairy cattle, we studied gait profiles of cows with no visible injuries (n = 17), sole lesions (n = 14), and sole ulcers (n = 7). Video recordings of dairy cows were digitized using motion analysis software to calculate 6 stride variables for each hoof. Compared with cows with sole ulcers, healthy cows walked faster (1.11 +/- 0.03 vs. 0.90 +/- 0.05 m/s, mean +/- SEM), had shorter stride durations (1.26 +/- 0.03 vs. 1.48 +/- 0.05 s), and longer strides (139.5 +/- 2.1 vs. 130.0 +/- 3.2 cm). Percentage of triple support in the gait cycle (time when cattle were supported by 3 legs) more than doubled for cows with sole ulcers compared with healthy cows (42 vs. 18%). Gait differences were likely due to cows reducing the load on an affected leg. Few differences were detected between healthy cows and those with sole lesions, perhaps because of variation in number, severity, and location of injuries. Kinematic gait analysis is a promising approach in understanding how hoof pathologies affect dairy cow gait.

Segregated early weaning and welfare of piglets

Segregated early weaning (SEW), introduced with the objectives of eradicating or controlling diseases and improving performance, is becoming increasingly popular among producers. The main features of SEW are weaning piglets early and moving the newly weaned piglets to a site isolated from the sows and other animals. In this article, we describe the key features of SEW and factors leading to its development. We review some of the main welfare issues involved with raising pigs in this way. We describe experiments that were crucial in the development of SEW and that showed positive effects on the health status and weight gain of piglets. We also review experiments that indicated welfare problems associated with this system. Specifically, we look at the effects of early weaning on the behavior and well-being of piglets. In addition, we look at other features of SEW, such as repeated cross-fostering and transport of young piglets. We provide directions for future research and offer recommendations for producers.

Effect of Hoof Pathologies on Subjective Assessments of Dairy Cow Gait

To explore how hoof pathologies affect dairy cattle gait, we studied cows with sole hemorrhages (n = 14), sole ulcers (n = 7), and those with no visible injuries (n = 17). Overall gait assessments, scored from video using a 1 to 5 numerical rating system (1 = sound, 5 = severely lame) and a continuous 100-unit visual analog scale, found cows having sole ulcers had poorer gait than healthy cows (mean +/- SEM: 4.0 +/- 0.13 vs. 3.1 +/- 0.08, and 59 +/- 3 vs. 46 +/- 2, respectively). Six gait attributes (back arch, head bob, tracking-up, joint flexion, asymmetric gait, and reluctance to bear weight) were also assessed using continuous 100-unit scales. Compared with healthy cows, those having sole ulcers walked with a more pronounced back arch (12 +/- 3 vs. 28 +/- 4), more jerky head movement (2 +/- 2 vs. 10 +/- 3), shortened strides (7 +/- 2 vs. 26 +/- 4), and more uneven weighting among the limbs (16 +/- 2 vs. 32 +/- 3). Of all measures, the numerical rating system most effectively discriminated healthy cows from those with sole ulcers (R2 = 0.73), classifying 92% of animals correctly. No differences were detected among cows with and without sole hemorrhages. Intra- and interobserver reliabilities were reasonable for all measures (R2 > or = 0.64) except joint flexion and asymmetric gait. In summary, subjective assessments of dairy cattle gait provide valid and reliable approaches to identifying cattle with sole ulcers.