Invited review: Lying time and the welfare of dairy cows.

Adequate time lying down is often considered an important aspect of dairy cow welfare. We examine what is known about cows' motivation to lie down and the consequences for health and other indicators of biological function when this behavior is thwarted. We review the environmental and animal-based factors that affect lying time in the context of animal welfare. Our objective is to review the research into the time that dairy cows spend lying down and to critically examine the evidence for the link with animal welfare. Cows can be highly motivated to lie down. They show rebound lying behavior after periods of forced standing and will sacrifice other activities, such as feeding, to lie down for an adequate amount of time. They will work, by pushing levers or weighted gates, to lie down and show possible indicators of frustration when lying behavior is thwarted. Some evidence suggests that risk of lameness is increased in environments that provide unfavorable conditions for cows to lie down and where cows are forced to stand. Lameness itself can result in longer lying times, whereas mastitis reduces it. Cow-based factors such as reproductive status, age, and milk production influence lying time, but the welfare implications of these differences are unknown. Lower lying times are reported in pasture-based systems, dry lots, and bedded packs (9 h/d) compared with tiestalls and freestalls (10 to 12 h/d) in cross-farm research. Unfavorable conditions, including too few lying stalls for the number of cows, hard or wet lying surfaces, inadequate bedding, stalls that are too small or poorly designed, heat, and rain all reduce lying time. Time constraints, such as feeding or milking, can influence lying time. However, more information is needed about the implications of mediating factors such as the effect of the standing surface (concrete, pasture, or other surfaces) and cow behavior while standing (e.g., being restrained, walking, grazing) to understand the effect of low lying times on animal welfare. Many factors contribute to the difficulty of finding a valid threshold for daily lying time to use in the assessment of animal welfare. Although higher lying times often correspond with cow comfort, and lower lying times are seen in unfavorable conditions, exceptions occur, namely when cows lie down for longer because of disease or when they spend more time standing because of estrus or parturition, or to engage in other behaviors. In conclusion, lying behavior is important to dairy cattle, but caution and a full understanding of the context and the character of the animals in question is needed before drawing firm conclusions about animal welfare from measures of lying time.

Effect of age of introduction to an automated milk feeder on calf learning and performance and labor requirements.

Group housing of dairy calves with automated milk feeders (AMF) is increasingly being used, but the effect of introducing calves to the AMF at a very young age (<24 h) on calf performance, health, and welfare, as well as farm personnel labor requirements are unknown. The objective of this controlled trial was to investigate whether early (<24 h after birth) introduction of calves affects the time to learn how to drink from the AMF, labor requirements for feeding milk during the learning phase, and average daily gain during the milk-feeding period compared with calves conventionally introduced at 5 d of age. Sixty Holstein calves (heifers and bulls) were assigned at birth to either early introduction (<24 h after birth) or conventional introduction (at 5 d of age) to the group pen with AMF. After birth, calves were housed in individual pens and then introduced, based on assigned treatment, to the group pen with an AMF and a continuous flow stocking approach. Calves were fed milk replacer and gradually weaned from d 47 to 60 of age. Calves had access to starter from 5 d of age, and to water and straw right after colostrum feeding. We measured the time between first training to use the AMF and first unassisted visit to the AMF with milk intake, the number of assisted visits until the calf was independent in its use of the AMF (successful learning), and the total time required for milk feeding (labor) until successful learning. Calves were weighed at birth, 30, 46, and 61 d of age, and were monitored daily for signs of disease. Daily milk and starter intake per calf were automatically recorded. Early-introduced calves took longer to successfully learn to use the AMF {64.9 h [95% confidence interval (CI) = 59.1 to 77.9] vs. 31.4 h (95% CI = 22.8 to 47.9)} and tended to require more assisted visits [7.8 visits (95% CI = 6.2 to 9.7) vs. 5.9 visits (95% CI = 4.8 to 7.5)] compared with conventionally introduced calves. Labor for milk feeding was greater for conventionally introduced calves relative to early-introduced calves [145.6 min (95% CI = 125.1 to 169.4) vs. 39.9 min (95% CI= 33.5 to 47.6)]. Disease risk was similar between treatments but the risk of severe versus mild diarrhea was greater for early- compared with conventionally introduced calves (odds ratio = 4.7; 95% CI 1.01 to 31.1). Early-introduced calves consumed less milk during the first days of life compared with conventionally introduced calves (d 2 = 5.5 vs. 6.4 L; d 3 = 7.0 vs. 8.2 L; d 4 = 7.0 vs. 8.4 L; d 6 = 6.4 vs. 7.9 L; d 7 = 6.0 vs. 7.0 L, respectively), with no differences after 8 d. We found no effect of treatment on average daily gain. Although introducing calves <24 h after birth required more assistance to use the AMF, farm labor for milk feeding tasks was less for early-introduced calves. Thus, with early introduction to AMF, a trade-off may exist between reduced labor per calf, with no effect on weight gain, but potentially a higher risk of severe diarrhea (vs. mild).

Associations between management practices and within-pen prevalence of calf diarrhea and respiratory disease on dairy farms using automated milk feeders.

Data on management practices used with automated milk feeders (AMF) are needed to identify factors associated with calf health in these systems. The objectives of this observational, longitudinal, cross-sectional study were to estimate the prevalence of calf diarrhea (CD) and bovine respiratory disease (BRD), and to identify factors associated with prevalence of these diseases at the pen level on dairy farms feeding milk to group-housed calves with AMF. Seventeen dairy farms with AMF in Ontario, Canada, were visited 4 times, seasonally, over 1 yr. The clinical health of all calves (n = 1,488) in pens (n = 35) with AMF was scored to identify the number of calves with CD and BRD. Data on calf, feeder, and pen management practices were analyzed using generalized linear mixed regression models for each disease. Overall calf-level prevalence of CD and BRD were 23 and 17%, respectively. Median (interquartile range, IQR) within-pen prevalence of CD and BRD were 17% (7 to 37%) and 11% (0 to 28%), respectively. Median age (IQR) for diarrheic calves was 25 d (16 to 42 d), and for calves with BRD was 43 d (29 to 60 d). Factors associated with lower within-pen prevalence of CD were the administration of vitamin E and selenium at birth [odds ratio (OR) = 0.56; 95% confidence interval (CI): 0.32 to 0.99], feeding of probiotics (OR = 0.44, 95% CI: 0.22 to 0.93), and adding fresh bedding every 2 to 3 d (OR = 0.43; 95% CI: 0.24 to 0.76) compared with every 7 or more days. In contrast, sharing air with older cattle (>9 mo old) was associated with increased within-pen prevalence of CD (OR = 4.54, 95% CI: 1.88 to 10.52). Additionally, total bacteria counts ≥100,000 cfu/mL in milk samples taken from the AMF mixing jar were associated with increased within-pen prevalence of CD during the summer visit (OR = 3.34; 95% CI: 1.31 to 8.54). Increased total solids in milk or milk replacer (OR = 0.48, 95% CI: 0.27 to 0.85) and feeding whole milk versus milk replacer (OR = 0.29, 95% CI: 0.11 to 0.75) were associated with lower within-pen prevalence of BRD. Factors associated with greater within-pen prevalence of BRD were sharing air with weaned cattle up to 8 mo old (OR = 3.21, 95% CI: 1.26 to 8.16), and greater depth of the wet bedding pack. The use of maternity pens for reasons other than just calving was associated with increased prevalence of both CD and BRD (OR = 1.85, 95% CI: 1.03 to 3.33; OR = 2.61, 95% CI: 1.21 to 5.58, respectively). These results suggest that isolation from older animals and frequent cleaning of the feeder and pen may help to reduce disease prevalence in group-housed calves fed with an AMF.

A survey of dairy calf management practices among farms using manual and automated milk feeding systems in Canada.

Dairy calves in North America traditionally are housed individually and fed by manual milk feeding (MMF) systems with buckets or bottles. Automated milk feeders (AMF) allow for more natural milk feeding frequencies and volumes, and calves are usually housed in groups. The objectives of this study were to (1) determine the prevalence of various milk-fed calf management and feeding practices and (2) compare these practices between dairy farms using MMF and AMF systems. A national online survey was performed from January to May 2015 to quantify management practices for the care of milk-fed dairy calves in Canada. A total of 670 responses were received (6% of all dairy farms in Canada). Among respondents, 16% used AMF and 84% used MMF. Seventy percent of the farms using AMF had freestall barns compared with only 48% of those using MMF. A greater proportion of AMF farms (30%) also had automatic milking systems (AMS) compared with MMF farms (8%). Among tiestall farms, a herd size of >80 milking cows was associated with having an AMF [odds ratio (OR) = 3.8; 95% confidence interval (CI): 1.6-11.4]. For freestall or bedded-pack farms, a herd size of >80 milking cows (OR = 3.5; CI: 1.8-6.6), having an AMS (OR = 3.1; CI: 1.6-5.7), and use of cow brushes (OR = 3.1; CI: 1.3-6.9) were associated with having an AMF. Calves fed with AMS typically were housed in groups of 10 to 15, whereas almost 76% of the farms with MMF housed calves individually. Although both AMF and MMF farms fed similar amounts of milk in the first week of life (median = 6 L/d), the cumulative volume fed in the first 4 wk differed significantly, with a median of 231 versus 182 L for AMF and MMF, respectively. Median peak milk allowance was higher for AMF than for MMF (10 vs. 8 L/d, respectively). In summary, farms using AMF were larger, provided more milk to calves, and used more automation in general (i.e., in other areas of their operation). These data provide insights into calf-rearing practices across Canada and into how the use of AMF is affecting calf feeding and management on dairy farms.

Reciprocated cross sucking between dairy calves after weaning off milk does not appear to negatively affect udder health or production.

Cross sucking by dairy calves occurs most commonly before weaning, but is of most concern in older animals where it has been claimed to cause mastitis and udder damage. Providing ad libitum milk allowance via a teat and gradual weaning reduces cross sucking, but low levels of this behavior still persist. Our aims were to understand why this behavior persists in some calves after weaning off milk and to examine whether individuals which are cross sucked postweaning are more likely to sustain teat injury or develop mastitis during their first lactation. Fifty-six female Holstein calves were housed in groups of 8 and fed milk, grain, and hay ad libitum from automated feeders. During weaning, milk allowance was gradually reduced according to grain intake. Cross sucking was recorded using overhead video cameras (5 observation periods of 72h). The effects of weaning on cross sucking were examined; to examine whether cross sucking affected udder health, all incidences of damaged quarters or clinical and sub-clinical mastitis in the first lactation were recorded, as was milk production. The overall level of cross sucking after weaning, at 4 to 5mo of age, was low and a small proportion of individuals accounted for the majority of events. The duration of cross sucking that occurred at 4 to 5mo of age was correlated with the amount of cross sucking done before and immediately after weaning. After weaning, the calves that cross sucked did so on certain calves, with the most sucked calf within each pen accounting for 73.98% of all cross-sucking events. No relationship was found between cross sucking and being cross sucked in the period before weaning but a positive correlation was found by 4 to 5mo of age. The majority of calves reduced or ceased cross sucking after weaning. Individuals still observed to be cross sucking by 4 to 5mo of age had formed pairs with other cross-sucking individuals and cross-sucking events occurred almost exclusively between these pairs. Cows that were cross sucked as heifers were no more likely to develop mastitis or have higher somatic cell count in their first lactation than those which were not involved in cross sucking. Cross sucking typically begins before weaning, but the formation of lasting pairs of reciprocal cross-sucking partners after weaning may be responsible for this behavior persisting in group housed dairy calves after weaning off milk. Low levels of cross sucking did not appear to have a negative effect on udder health.

Using automated feeders to wean calves fed large amounts of milk according to their ability to eat solid feed.

Dairy calves weaned off milk at an early age show signs of hunger and can lose weight. We examined whether using automated feeders to wean calves according to individual voluntary solid feed intake reduced the effects of weaning. Female Holstein calves were housed in groups of 5 to 9. All calves were fed 12 L/d milk and ad libitum grain starter and hay from automated feeders immediately after grouping, and were allocated to 3 weaning strategies: (1) early-weaned (EW; n=14): weaning began on d 40, and milk allowance gradually decreased until weaning was complete on d 48; (2) late-weaned (LW; n=14): weaning began on d 80 and was completed on d 89; (3) weaned by starter intake (WSI; n=28): weaning began when calves consumed 200g/d of starter and was completed when the calves consumed 1,400g/d. Each day, the automated feeders recorded quantities of milk, starter, and hay eaten by all calves, as well as the frequency of visits to the milk feeder; we used unrewarded visit frequency as a sign of hunger. Body weights (BW) were recorded weekly. We estimated daily digestible energy (DE) intake for each calf based on the milk, hay, and starter consumed. Average daily gains (ADG) were expressed as percent of BW. For calves in WSI, weaning began at 54.7±18.9 d (mean ± SD) of age, the duration of weaning was 21.1±10.6 d, and weaning ended at 75.8±10.7 d of age. Both LW and WSI calves had better ADG from wk 3 to 13 than EW calves. Calves in the WSI group drank less milk and ate more starter than LW calves but had similar ADG. During the period of weaning, EW calves made more unrewarded visits to the milk feeder than LW and WSI calves. Three EW calves lost weight during weaning, whereas all LW and WSI calves gained weight. Calves differ greatly in when they begin to eat solid feed and how quickly they increase the intake in response to a decrease in milk allowance. An advantage of automated feeders is that calves can be weaned at variable ages depending on their ability and willingness to eat solid feed, which reduces signs of hunger and improves weight gains during weaning.

Automated and visual measurements of estrous behavior and their sources of variation in Holstein heifers. II: Standing and lying patterns.

Lying (LY) and standing (ST) behavior of Holstein heifers (n = 57) was studied from Day -7 to Day +2 relative to estrus (Day 0) using leg-mounted accelerometers. A total of 269 estrus episodes were studied. The objectives were to quantify the effects of estrus on ST and LY patterns, identify sources of variation, and provide insight into new approaches for the use of sensors in estrus detection. The sensors were used to obtain ST bout frequency (bouts per day), total daily ST time, and mean bout duration and duration of the longest bout for ST and LY on a daily basis. Estrus episodes were identified using walking activity peaks and validated by ovarian ultrasonography. Repeated-measures ANOVA was used to analyze the effects of estrus order (pubertal vs. second and greater), season, time of estrus onset, category of baseline walking activity, and number of heifers simultaneously in estrus on ST and LY variables. Overall, ST bout frequency was lower, whereas mean ST bout duration, duration of the longest ST bout, and total daily ST time were longer on Day 0 (P < 0.05). The longest ST bout increased from 232 ± 5 minutes on Day -7 to 488 ± 16 minutes on Day 0 (P < 0.05), and on Day 0, it started within -2 to 4 hours of time of estrus onset. Measurements of ST bouts varied the most on Day 0 (coefficient of variation = 21.5%-52.8%). The pubertal estrus was characterized by smaller increase in mean ST bout duration, longest ST bout duration, and total daily ST time (P < 0.05) compared to the second and greater episodes. Second and greater episodes had greater longest LY bout on Day +1, but on Day 0 it was not different from other nonestrus days (P < 0.01). The longest ST bout on Day 0 was longer for heifers with high baseline walking activity and for episodes occurring during the cold season (P < 0.05). The effect of estrus on ST variables for morning-onset episodes was observed only on Day 0. Episodes with afternoon and night onset showed the effect of estrus spread over Days -1 and 0, resulting in a smaller change between Day -7 and Day 0. The number of heifers simultaneously in estrus did not affect the studied variables (P > 0.05). Measurements of ST and LY changed during estrus and were correlated to walking activity. The large increase in duration of the longest ST bout and its occurrence in proximity of estrus onset suggest potential for automation. Incorporating measurements of ST and LY corrected for sources of variation could improve estrus detection systems.

Urination and defecation by group-housed dairy calves.

A better understanding of when and where group-housed calves are most likely to defecate or urinate might permit improved housing design or more efficient use of cleaning routines. However, this is the first study to address the urination and defecation habits of calves. The primary aims of this study were to report the daily frequency of calves' urination and defecation and determine when and where group-housed dairy calves defecate and urinate most frequently. We were also interested to see if incidence of urination and defecation changed with increasing age and the change in diet at weaning. We observed 36 female Holstein calves, housed in groups of 9, and fed milk, grain, and hay from automated feeders. For the purposes of another experiment, these calves were assigned to 1 of 3 experimental treatments relating to age at start of weaning and milk allowance: low milk allowance and early weaning (6 L/d, 42 d), high milk allowance and early weaning (12 L/d, 42 d), and high milk allowance and late weaning (12 L/d, 84 d) The occurrence of defecations and urinations was determined by continuous observation of video recordings taken over 72 h at 2 age periods (age, mean ± SD; period 1=32.0 ± 11.13 d and period 2=61 ± 11.29 d). Due to the treatments, weaned and unweaned calves were observed in each period (period 1: 34 unweaned and 2 weaned calves; period 2: 16 unweaned and 20 weaned calves). Large differences were found between calves in mean daily frequency of total urinations and defecations across a 3-d period (mean=17.56 ± 5.07/d, range=4.33 to 28.67). Differences between individual calves did not change significantly over time, provided calves remained unweaned. Two days of observation was sufficient to give a reliable estimate of daily urination and defecation frequency. Frequency of urination and defecations was higher in calves postweaning. Higher age and visits to the milk feeder were associated with a higher frequency of urinations and defecations preweaning. After weaning, frequency of eliminations increased with increasing visits to the water feeder. An effect of time of day was observed, with significantly more events during daylight hours (0600-1800 h) in comparison to night (1800-0600 h). Before weaning, calves urinated and defecated significantly more on slatted flooring and sawdust-bedded areas than within the feeder (daily mean ± SD=6.96 ± 3.15, 6.49 ± 3.90, and 4.10 ± 2.67 for slatted floor, bedded floor, and feeder areas, respectively). Frequency of eliminations in feeders and slatted, but not sawdust-bedded, areas was higher in calves postweaning. Calves urinate and defecate more frequently during daylight hours when they are more active. Slatted flooring around feeders is useful to reduce soiling of bedded areas, particularly as calves increase in age.

Technical note: a comparison of 2 methods of assessing lameness prevalence in tiestall herds.

We compared 2 methods for identifying lame cows and estimating the prevalence of lameness in tiestalls. Cows (n=320) in 9 tiestall herds were scored as lame both by the presence of limping while walking and by stall lameness scores (SLS). The SLS was based on the number of the following behaviors that the cow showed while standing in the tiestall: weight shifting, standing on the edge of the stall, uneven weight bearing while standing, and uneven weight bearing while moving from side to side. Two observers watched video-recordings of the cows. Intraobserver agreements for the 4 SLS behaviors ranged from 92 to 100%, and interobserver agreement ranged from 81 to 100%. The overall prevalence of lameness based on an SLS of ≥2 was similar to that of limping (39 vs. 40%). The sensitivity of the classification based on the SLS was 0.63 and the specificity was 0.77 in identifying cows with a limp; accuracy varied across farms from 62.2 to 80.4%, with a mean of 71.7%. A cow with an SLS of ≥2 had 4.88 times the odds of limping than a cow with an SLS of <2. The prevalence of lameness on farms based on SLS was highly correlated with the prevalence of limping (Pearson correlation=0.88; n=9), and prevalence estimates from the 2 methods diverged most when the mean herd prevalence was lower. The SLS method provides an estimate of the prevalence of lameness in tiestall herds comparable with traditional gait scoring, but does not require that the cows be untied. The SLS method could be used to improve lameness detection on tiestall farms and obtain estimates of lameness prevalence without the need to walk the cows.

Use of three-dimensional acceleration sensing to assess dairy cow gait and the effects of hoof trimming.

The aim of this study was to assess the use of three-dimensional acceleration sensing to describe the gait of dairy cows and the effect of hoof trimming. In Trial 1, a three-dimensional acceleration sensor was attached to the carpal region of a front leg of six Holstein cows who were then walked for 9 m. Results showed that measures of acceleration could clearly show the presence of steps, which were divided into an acceleration phase, which involved the hoof descending to and ascending from the ground, and a non-acceleration phase, which included the swing phase. Lissajous figures could succinctly depict the degree of acceleration for each cow and showed that one cow who was lame walked with greater vertical and lateral acceleration than the remaining cows. In Trial 2, 17 loose-housed Holstein cows were walked for 20 m during the month before, once during the month after and once 2 months after hoof trimming with the sensor attached at the end of their thoracic vertebrae to measure acceleration of the whole body. To relate the acceleration of the body to movements of the legs, image analysis was used to the range of vertical movement of four major skeletal joints, using visual markers attached to them. Hoof trimming significantly (P < 0.005) decreased both the range of vertical movement of the joints of front and hind legs and the variance of lateral and forward acceleration at the end of the thoracic vertebrae, suggesting improved gait pattern smoothness. Acceleration sensing was able to characterize variation among gait patterns of the cows and could reproduce the pattern shown by image analysis. This study demonstrates that three-dimensional acceleration sensing of either the carpal region of a front leg or the end of the thoracic vertebrae is useful to detect walking irregularities and evaluate the effectiveness of hoof trimming on walking ability of cattle.