D.M. Weary

BOARD-INVITED REVIEW: Using behavior to predict and identify ill health in animals1

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.

Invited review: The welfare of dairy cattle--key concepts and the role of science.

Concerns about the welfare of animals typically include 3 questions: is the animal functioning well (e.g., good health, productivity, etc.), is the animal feeling well (e.g., absence of pain, etc.), and is the animal able to live according to its nature (e.g., perform natural behaviors that are thought to be important to it, such as grazing)? We review examples, primarily from our own research, showing how all 3 questions can be addressed using science. For example, we review work showing 1) how common diseases such as lameness can be better identified and prevented through improvements in the ways cows are housed and managed, 2) how pain caused by dehorning of dairy calves can be reduced, and 3) how environmental conditions affect cow preferences for indoor housing versus pasture. Disagreements about animal welfare can occur when different measures are used. For example, management systems that favor production may restrict natural behavior or can even lead to higher rates of disease. The best approaches are those that address all 3 types of concerns, for example, feeding systems for calves that allow expression of key behaviors (i.e., sucking on a teat), that avoid negative affect (i.e., hunger), and that allow for improved functioning (i.e., higher rates of body weight gain, and ultimately higher milk production).

Invited review: Effects of milk ration on solid feed intake, weaning, and performance in dairy heifers

A feeding regimen that allows a smooth transition from milk to solid feed is vital for successful heifer-rearing programs. In the past, research efforts have focused on the development of feeding methods that allow early weaning, perhaps because the risk of disease is highest during the milk feeding stage. To encourage early intake of calf starter, conventional feeding programs have limited the supply of milk (often to 10% of BW at birth). However, dairy calves provided free access to milk will typically consume more than twice this amount. We critically review the available literature examining the relationship between milk feeding method, solid feed consumption, and rumen development in young dairy calves and identify areas where new work is required. We conclude that milk-fed dairy calves can safely ingest milk at approximately 20% of body weight (BW)/d, and greater milk consumption supports greater BW gain, improved feed efficiency, reduced incidence of disease, and greater opportunity to express natural behaviors, which in combination suggest improved welfare. Method of weaning greatly influences feed consumption, rumen development, and growth check in calves provided higher amounts of milk. Gradual weaning encourages starter intake during the preweaning period, and both weaning age and duration of weaning influence this consumption. Increased solid feed consumption during the weaning process contributes to rumen development, permitting higher starter intake and BW gain after weaning. Growth factors in milk may also enhance the growth and maturation of the gastrointestinal tract, but more research is required to understand the role of these factors. Greater nutrient supply through increased amount of milk appears to improve immune function and long-term performance of heifer calves; for example, reducing the age at first breeding and increasing first-lactation milk yield, but more research is needed to confirm these effects.

Effects of early separation on the dairy cow and calf 1. Separation at 6 h, 1 day and 4 days after birth

The aim of this study was to evaluate the effects of age of separation on the behavioural responses of the dairy calf and cow. Calves were separated from their dams 6 h, 1 day, or 4 days after birth (n=9 cow-calf pairs in each of the 3 treatment groups) and behaviour was video and audio taped from 1 h before separation to 21 h after separation. In the hour immediately before separation, we found that the younger calves tended to call and move more in the pen, and spent more time standing than the older calves, but after separation these trends reversed. Calves separated at older ages made significantly more movements in the pen (P<0.05), spent more time standing (P<0.05) and spent more time with the head out of the pen (P<0.01) than calves separated soon after birth. We observed a similar pattern for the cows. Before separation, cows with younger calves moved more frequently about the pen (P<0.05), and called at much higher rates (a mean of 40.7 calls during 40 min for cows on the 6-h treatment, vs. 0.2 calls for cows in the 4-day group; P<0.001). After separation, cows in the 4-day group called at approximately four times the rate of those separated at 6 h or 1 day (P<0.01). Moreover, the calls produced by cows separated later had a significantly higher fundamental frequency (P<0.001) and a lower emphasized harmonic (P<0.02) than the calls of cows separated from calves soon after birth. There was no difference between treatment groups in the other behavioural measures, either before or after separation. Calves separated at older ages tended to require fewer days of treatment for scouring, but calf weight gain and cow milk production did not differ among treatment groups. In conclusion, behavioural responses of both the cow and calf increase in relation to calf age at separation. However, there may be health advantages associated with delayed separation that compensate for the increased behavioural response.

Effects of early separation on the dairy cow and calf

This study investigated the effects of separating dairy calves from their mothers at 1 day (early separation) and 14 days (late separation) after birth. Behavioural observations were conducted on 24 Holstein dairy cow-calf pairs during the first 24h after separation. Before separation, cow-calf pairs were generally inactive. After separation, cows from the late-separation treatment group showed higher rates of calling, movement and placing the head outside the pen, than cows in the early-separation group. Parity did not influence cow behaviour. During the first 2 weeks after calving, cows in the late-separation group (i.e. still with their calves) yielded less milk at milking, a difference at least partly due to the milk consumed by the calf. Milk yields from days 15-150 did not differ between the two groups. After separation, calves in the late-separation group moved and placed their heads outside the pen more often than early-separation calves. During the first 14 days after birth, late-separation calves gained weight at more than three times the rate of those separated early. When introduced to an unfamiliar calf at 6 weeks of age, calves from the late-separation group showed more intense social behaviour towards the unfamiliar calf than did those calves separated early. Thus, the response to separation by both cows and calves increased when calves were separated at 2 weeks rather than 1 day of age, but calves separated at the later age gained more weight and delayed separation appeared to influence the development of calf social behaviour.

Calling by Domestic Piglets: Reliable Signals of Need?

Abstract Two manipulations were performed on domestic piglets to determine whether differences in calling during periods of separation from the mother can indicate differences in need. In both cases, the aim was to manipulate the piglets need for the sows attention. In the first manipulation a ‘thriving’ piglet (i.e. the piglet with the heaviest weight and most rapid weight gain) and a ‘non-thriving’ one (lightest and slowest weight gain) were selected from each of 15 litters. The two piglets were removed from the sow and litter and recorded for 13 min in separate isolated enclosures. For the second manipulation, two piglets of intermediate weight and weight gain were selected from each of the same 15 litters and were removed from the sow during nursing under one of two conditions. The ‘unfed’ piglet was removed just before the milk ejection and the ‘fed’ one just after receiving milk. Both were recorded as in the first manipulation. ‘Non-thriving’ and ‘unfed’ piglets called more and used more high-frequency calls, longer calls, and calls that rose more in frequency than their ‘thriving’ and ‘fed’ litter-mates. By means of a playback experiment, the assumption that sows respond to these piglet calls was tested. Sows were more likely to vocalize and approach the loudspeaker during playback of the piglet isolation calls than during playback of white noise. It is argued that if a piglets calls provide reliable information about its need for the sows resources, then this calling can be used as a measure of its welfare. These results are consistent with theoretical models of honst signalling.

Vocal response to pain in piglets

Abstract Three experiments were performed attempting to establish the validity of vocal measures as an indicator of the immediate response to pain in domestic piglets. Vocalisations were measured while piglets were subjected to the routine farm practice of castration without anaesthetic, or restrained identically but not castrated (i.e., sham-castrated). In Experiment 1 we measured how calling changed during the different stages of the procedure, and in Experiments 2 and 3 we measured the effect of different restraint techniques. Piglets that were castrated produced significantly more high frequency calls (>1000 Hz) than sham castrates in all three experiments. In Experiment 1, we found the greatest differences between the castrated and sham piglets during the severing of the spermatic cords (1.0 high calls/s vs. 0.3 calls/s, P

Technical note: Validation of a system for monitoring rumination in dairy cows

Increased rumination in dairy cattle has been associated with increased saliva production and improved rumen health. Most estimates of rumination are based on direct visual observations. Recently, an electronic system was developed that allows for automated monitoring of rumination in cattle. The objective was to validate the data generated by this electronic (Hi-Tag, SCR Engineers Ltd., Netanya, Israel) rumination monitoring system. Assessments of 2 independent observers were highly correlated (r = 0.99, n = 23), indicating that direct human observations were suitable as the reference method. Measures from the Hi-Tag electronic system were validated by comparing values with those from a human observer for fifty-one 2-h observation periods from 27 Holstein cows. Rumination times (35.1 +/- 3.2 min) from the electronic system were highly correlated with those from direct observation (r = 0.93, R(2) = 0.87, n = 51), indicating that the electronic system was an accurate tool for monitoring this behavior in dairy cows.

Lying behavior as an indicator of lameness in dairy cows

Lameness is widely recognized as one of the most serious welfare and production concerns in the dairy industry. Our objectives were to evaluate the associations between lying behavior and lameness, and to determine whether lying behavior can be used as a diagnostic tool for lameness. Electronic data loggers recorded lying behavior of 1,319 cows from 28 farms at 1-min intervals for 5 d. These cows were gait scored according to a 5-point Numerical Rating System (NRS), and categorized as NRS <or=2, NRS=3, or NRS=4; no cow was scored as NRS=5. Lameness was dichotomized twice: LAME (NRS >or=3) and SEVLAME (NRS=4). Data were divided into 2 groups: 11 farms using deep-bedded stalls (DB) and 17 farms using mattress stalls (MAT). Differences in the daily lying time (h/d), frequency of lying bouts (n/d), duration of lying bouts (min/bout), and the standard deviation of bout duration (min/bout) between LAME or SEVLAME cows and those that were not were tested using mixed models. Receiver operating characteristic curves were constructed to identify behavioral thresholds to distinguish SEVLAME cows from the rest. Odds ratios for SEVLAME were estimated using logistic regression. Overall, 28.5% of cows were LAME including 7.3% that were SEVLAME. The prevalence of SEVLAME was higher on MAT farms than on DB farms (9.3+/-1.3 vs. 4.4+/-1.2%, respectively). SEVLAME cows on DB farms spent 12.8 [confidence interval (CI): 12.0 to 13.7] h/d lying down compared with 11.2 (CI: 10.7 to 11.8) h/d for cows that were not SEVLAME. These cows had longer duration of lying bouts [95.3 (CI: 84.6 to 107.3) vs. 80.3 (CI: 74.9 to 86.1) min/bout] and greater SD of bout duration [44.4 (CI: 41.1 to 48.0) vs. 50.7 (CI: 44.1 to 58.3) min/bout]. There were no behavioral differences among lameness categories on MAT farms. Within DB farms, cows with lying times >14.5 h/d had 16.2 (5.8 to 45.2) times higher odds of being SEVLAME. Cows with average lying bouts >90 min/bout were at 3.0 (1.2 to 7.4) times higher odds of being SEVLAME, and cows with average SD of bout duration >55 min/bout were at 4.1 (1.7 to 9.9) times higher odds of being SEVLAME. These results show that high lying times, long lying bouts, and variability in the duration of lying bouts were associated with lameness, and that stall surface influenced the behavioral responses of lame cows.

Lying behavior: Assessing within- and between-herd variation in free-stall-housed dairy cows

One of the most important design criteria for dairy cow housing is access to a comfortable lying area. Behaviors such as the time cows spend lying down and how often they lie down can be used to evaluate the quality of stalls; however, assessing lying behavior on farms can be challenging. Indices such as the cow comfort index (CCI) and stall use index (SUI) have been widely used in on-farm assessments. The aims were to establish reliable sampling and recording methods for measuring lying behavior, to evaluate the adequacy of the CCI and SUI as estimates of lying behavior, and to describe variation in the lying behaviors of free-stall-housed dairy cows. The time spent lying down and the number of lying bouts for 2,033 cows on 43 farms were recorded for 5 d using electronic data loggers sampling at 1-min intervals. The CCI and SUI were calculated based on a single observation taken 2 h before the afternoon milking on each farm. Subsets of data were created, including 4, 3, 2, or 1 d per cow and 40, 30, 20, 10, 5, or 1 cow(s) per farm. The estimates derived from each sample size were compared with the overall means (based on 5 d and 44 cows per farm) for lying time and number of lying bouts, and the CCI and SUI were compared with the farm means of lying time, number of lying bouts, and bout duration using linear regression. Recording 30 or more cows for 3 d or more represented the overall means with high accuracy (R(2) > 0.9), but using fewer cows or fewer days per cow resulted in poorer estimates of the farm mean. The CCI and SUI showed no association with the daily lying time (h/d; R(2) < 0.01), and CCI was only weakly associated with the number of lying bouts per day (R(2) = 0.16) and bout duration (min/bout; R(2) = 0.09). Cows lay down 11.0 +/- 2.1 h/d in 9 +/- 3 bouts/d, with a bout duration of 88 +/- 30 min/bout. These values ranged from 9.5 to 12.9 h/d, 7 to 10 bouts/d, and 65 to 112 min/bout across farm means, and 4.2 to 19.5 h/d, 1 to 28 bouts/d, and 22 to 342 min/bout across individuals, showing that variation in lying behavior among individual cows within farm was greater than differences among farms.