Short communication: Heart rate variability,step, and rumination behavior of dairy cows milked in a rotary milking system

Step behavior, heart rate (HR), the high-frequency (HF) component of heart rate variability (HRV), the ratio of the low-frequency (LF) and HF components (LF/HF ratio) as well as rumination behavior during milking were investigated in dairy cows milked in a high-capacity rotary milking system (n = 49) to study animals' stress responses to the milking process. Cardiac parameters were analyzed for undisturbed standing (baseline) and for the stages of the morning, afternoon, and evening milking processes (i.e., driving animals from the barn to the pre-milking holding pen, pre-milking holding pen, preparation, milking, and waiting after milking in the milking stall). During driving, HR was greater than during all other stages. After driving, a gradual decrease in HR was observed. The HF decreased during driving, indicating a decrease in vagal tone compared with baseline. When animals were in the holding pen, vagal tone decreased, whereas sympathetic tone increased with lower values than recorded for baseline and driving. During preparation, HF values were still lower than those recorded for baseline. The recovery of the autonomic activity was observed following preparation as indicated by increased HF and decreased LF/HF ratio during milking and waiting stages. During milking, 53.1% of the animals ruminated. The frequency of steps was greater during preparation (3.7 ± 1.8 steps/min) than during milking (0.7 ± 0.4 steps/min) and waiting after milking (1.6 ± 1.0 steps/min). Our results suggest that being in the holding pen is stressful for cows; however, vagal predominance from the onset of milking, the low frequency of steps, and the high prevalence of rumination during milking suggest a possible welfare benefit of the investigated rotary milking system.     

Feeding behavior,milking behavior,and milk yields of cows milked in a parlor versus an automatic milking system

This study compared feeding and milking behavior and milk yields for cows housed in the same barn, fed the same ration, but milked with a conventional milking parlor (parlor) or automatic milking system (robot). Behavioral data were videotaped hourly 1 d/mo for 9 mo. Feeding behavior patterns differed and were more variable for parlor cows than for robot cows. Both groups had low feeding rates at night and early morning. Feeding activity increased after milking and feed delivery for parlor cows. Milking and feeding activity in the robot system increased after human intervention at 7 a.m.; feed bunk activity peaked 3 h later and remained relatively constant from 10 a.m. to 8 p.m. Percentages of cows at the feed bunk were significantly greater for robot cows than parlor cows only at 10 a.m. and 9 p.m. Batch milking of parlor cows with free access to feed, vs. sequential milking of robot cows, with restricted movement to feed by a one-way gate system, resulted in higher peak percentages of cows at the bunk for parlor cows. Lower, more consistent percentages of cows eating at one time suggests that less bunk space may be needed for cows in robotic milking systems. Higher percentages of cows were observed in the robot from 8 a.m. to 1 p.m. and again from 3 to 7 p.m. Percentages of cows in the robot holding area were greatest from 8 to 11 a.m. and 3 to 6 p.m. and were lowest from midnight to 6 a.m. Milk production over 39 d in summer for subsets of cows was slightly but significantly higher (26.4 vs. 25.8 +/- 0.2 kg/d) for cows in the robot group. Milking frequency, days in milk, parity, and maximum air temperature for 3 d (-2 d to day of observation) affected milk yield comparisons. Results have implications for design of feeding and handling facilities used with automated milking systems.     

Effects of flow-controlled vacuum on milking performance and teat condition in a rotary milking parlor

The objective of this study was to compare a vacuum control system that increases milking system vacuum during the peak flow period of milking to conventional constant vacuum control technology regarding its effect on milk flowrate and milking duration. Further objectives were to study the effects of flow-controlled vacuum on milking parlor performance. An observational study was conducted on a commercial dairy farm milking from 848 to 896 cows per day over the study period using a 60-stall rotary milking parlor. The flow-controlled vacuum control system was applied for 3 wk. Milking performance and teat condition were compared with 3-wk periods prior and subsequent to the test period using conventional vacuum control. Statistical analysis was performed assuming a cross-sectional study design during each period. Flow-controlled vacuum increased peak milk flowrate by 12% and increased average milk flowrate by 4%. The decrease in individual cow milking duration was proportional to milk yield per milking. Postmilking teat condition was good during the entire study period. The occurrence of rough teat ends was slightly reduced during the flow-controlled vacuum period with no meaningful difference in the occurrence of teats with blue color, palpable rings, or petechia. The combination of reduced vacuum during the low flow period of milking and the decrease in milking duration are likely factors that are protective of teat tissues. Bioeconomic modeling of the use of flow-controlled vacuum on the performance of rotary milking parlors, using the data that were collected during the study, showed that the reduction in milking duration of individual cows allows a higher rotary parlor speed. Modeled parlor throughput increased by 5.0% to 419 cows/h, 6.8% to 407 cows/h, and 4.2% to 326 cows/h when 80%, 95%, and 99% of the cows were finished milking at the end of the rotation for a 60-stall parlor. Model results showed that increased parlor throughput resulted in increased labor efficiency, reduced labor costs for milking, and a positive benefit-cost ratio on the investment for all but the smallest herd and parlor sizes considered.     

Cardiac responses to palpation per rectum in lactating and nonlactating dairy cows

Interest in the monitoring of heart rate variability (HRV) has increased recently, as it gives more detailed and immediate information about the level of stress than traditional behavioral or hypothalamus-pituitary-adrenal measures. In this study, we evaluated heart rate (HR) and parasympathetic HRV parameters to monitor cardiac stress responses to palpation per rectum (PPR) in lactating (LACT; n = 11) and nonlactating (NLACT; n = 12) dairy cows. Heart rate and HRV were recorded from 40 min before PPR until 120 min after it was completed. Heart rate, the root mean square of successive differences (RMSSD), and the high-frequency component (HF) of HRV were analyzed by examining 5-min time windows. To compare cardiac responses to PPR between groups, changes in HR and HRV parameters were calculated as area under the curve (AUC) for LACT and NLACT cows. An immediate increase in HR was detected during PPR in both LACT (+21.4 ± 2.4 beats/min) and NLACT cows (+20.6 ± 2.3 beats/min); however, no differences were found between groups on the basis of parameters of AUC. The increase in HR in both groups along with a parallel decrease in RMSSD (LACT cows: −5.2 ± 0.4 ms; NLACT cows: −5.1 ± 0.4 ms) and HF [LACT cows: −10.1 ± 0.8 nu (where nu = normalized units); NLACT cows: −16.9 ± 1.2 nu] during PPR indicate an increase in the sympathetic, and a decrease in the parasympathetic tone of the autonomic nervous system. The increase in RMSSD (LACT cows: +7.3 ± 0.7 ms; NL cows: +17.8 ± 2.2 ms) and in HF (LACT cows: +24.3 ± 2.6 nu; NLACT cows: +32.7 ± 3.5 nu) immediately after PPR indicated a rapid increase in parasympathetic activity, which decreased under the baseline values 10 min following PPR. The amplitude and the maximum RMSSD and HF values were greater in NLACT cows than in LACT animals, suggesting a higher short-term cardiac responsiveness of NLACT cows. However, the magnitude and the duration of the stress response were greater in LACT cows, as indicated by the analysis of AUC parameters (area under the HRV response curve and time to return to baseline). Cow response to the PPR was more prominent in parasympathetic HRV measures than in HR. Based on our results, the effect of PPR on the cows’ cardiac stress responses may have an impact on animal welfare on dairy farms, and investigating the effect of lactation on the cardiac stress reactions could prove useful in modeling bovine stress sensitivity. Further research is needed to find out whether the differences due to lactation are physiological or management related.     

Producer satisfaction, efficiency, and investment cost factors of different milking systems

A modernization survey was used to determine producer satisfaction, efficiency, and investment cost measures of different milking systems. The 301 producers included in this study expanded herd size by at least 50% for smaller herds (60 to 100 cows), or 40% for larger herds, (>100 cows) between 1994 and 1998. The milking systems analyzed and compared were stall barn with pipeline, flat barn parlor walk through and back-out, and herringbone or parallel parlor in old barn or new building. Investment costs per cow were higher for pit parlor in new building, $979. Parallel parlors had a higher cost per milking unit, $13,201, and cost per cow, $860, than herringbone, $8944 and $582, respectively. Herringbone parlors were used more hours per day, 10.75, than parallel parlors, 8.84, of similar size. Pit parlors in new buildings were more labor efficient, as measured by cows per worker hour, than stall barns with pipeline or flat parlor or pit parlors in old barns. Herringbone and parallel parlor in new building were similar for cows per hour (82 and 83) and cows per worker hour (41 and 43). Parallel or herringbone parlors in old barns had fewer cows per hour (63 and 58) than parallel or herringbone parlors in new buildings. Survey respondents showed greater satisfaction for time spent milking, physical comfort of milker, and milk quality for parlor types over stall barn with pipeline. Safety of operator satisfaction was higher for pit parlors than flat parlors or stall barn. No difference in satisfaction was observed between parallel and herringbone parlors.     

Effect of milking stall dimensions on upper limb and shoulder muscle activity in milkers

Increasing societal awareness for animal welfare can promote changes in legislation. Some of these changes may also affect the person that interacts with the animal in a shared workspace, such as in milking stalls. Swiss milking stalls were designed many years ago, when cows were smaller than they are today. A recent animal-based study indicated that welfare decreased in cows exposed to restricted space allowance in milking stalls, which had resulted from increasing body size without adjustment of milking stall dimensions. However, changing the milking stall dimensions without considering the milker may be detrimental. For many years, health issues, particularly of the upper limb and shoulders, have affected milking personnel. The current study investigated the effect of large and standard milking stall dimensions on muscle activity in milkers (as a measure of workload) during milking. This assessment is fundamental to ensure that legislation improving animal welfare does not jeopardize human health. The study took place in an experimental milking parlor that allowed for size adjustment of the individual milking stall. Nine milkers performed 2 shifts of milking in a herringbone and 2 shifts in a side-by-side milking parlor. The milking stall dimensions were large on one side and standard on the other side of the parlor; the 2 sides were switched between milking shifts. We used surface electromyography to monitor bilateral muscle activity of forearm (flexor carpi ulnaris), arm (biceps brachii), and shoulder (deltoideus anterior; upper trapezius) muscles. Statistical analysis was performed separately for the herringbone and the side-by-side parlor for each muscle using mean and maximum muscle activity as the target variables in a linear mixed-effects model. The analysis showed that the different milking stall dimensions did not consistently affect activity of the measured muscles. Our results suggest that milking stall dimensions are not a primary risk factor for poor ergonomics in parlor workers.     

Effects of small milking stalls on stress responses in dairy cows during milking in group milking parlors

Milking stall dimensions have not been adapted to the increase in cow body size caused by selection for better milking performance over the past decades. Improper milking stall dimensions might limit cow comfort, could lead to stress responses during milking and thus could negatively affect cow welfare. A crossover study was conducted in an experimental milking parlor that was converted from a herringbone (HB) to a side-by-side (SBS) parlor. The milking stall dimensions were modified in length and width and for HB also in depth (perpendicular distance between rump rail and breast rail). The stall dimensions applied during the experiments ranged from much smaller than common in European dairy farming to much larger. Treatments were applied for 2 wk per milking parlor type. In each milking parlor type, a total of 30 cows, kept in 2 groups were observed during milking for behavioral and physiological stress responses and for milking performance. In addition, milk cortisol levels and somatic cell counts were measured at the end of the 2-wk period. Outcome variables were selected based on a principal component analysis and analyzed using mixed effects models reflecting the experimental design. The results showed that the first cow per milking batch required more time (on average >40 s) to enter very small HB stalls than to enter small, large and very large stalls (<30 s). Also, cows yielded more milk per milking in very small and very large HB stalls than in the small and large milking stall dimensions [very small: 15.8 kg; 95% confidence interval (CI), 14.2–17.4 kg); small: 14.3 kg (95% CI, 12.8–15.9 kg); large: 14.6 kg (95% CI, 13.1–16.1 kg); very large: 16.1 kg (95% CI, 14.6–17.6 kg)]. The other behavioral, physiological and milk flow parameters as well as udder health were not affected by stall dimensions. For the SBS parlor, effects of milking stall dimensions were not detectable in any of the parameters. Despite the strong avoidance behavior to enter the milking parlor (measured as latency), no acute stress responses were found during milking. However, the study cannot exclude long-term effects of narrow stall dimensions on stress levels and possibly udder health, which should be investigated in future studies.     

Implications of prolonged milking time on time budgets and lying behavior of cows in large pasture-based dairy herds

In large Australian pasture-based dairy herds, it is common for the time taken to milk a herd of cows to be up to 4 h. Cows are collected from the paddock as a group, wait in turn in the dairy yard to be milked, and then return individually to the paddock or feed pad immediately after leaving the milking parlor. In such herds, we previously found a consistent milking order, resulting in some cows being regularly away from pasture for several hours per day more than others. Increased time away from pasture may affect the time budgets of cows because of decreased opportunity for grazing or lying down. Lying behavior is a high-priority behavior for cows, and the duration of lying has been used as an important measure of their welfare. We applied activity monitors for 7 d to 15 cows toward the beginning and 15 cows toward the end of the milking order in 10 dairy herds milking 500 to 730 cows as a single group to understand the effect of extra time spent in the dairy on lying behavior. Study cows typically produced 6,000 to 8,000 L in a 300-d lactation on rotary dairy platforms with 40 to 80 units, being fed 2.5 to 6 kg of grain mix in the milking parlor daily, with the rest of the diet being supplied as pasture or forage provided in the pasture or close to the exit of the dairy. Over the 10 farms, 1,948 cow-days were available for analysis. The furthest paddocks on each farm were 1.8 to 3.5 km walking distance from the dairy. A wide range of steps were taken each day, ranging from 1,705 to 15,075 (mean = 5,916). The main predictor of the number of steps was the farm on which the cows were located. Cows that spent less than an hour waiting to be milked (and would be unlikely to have their ability to lie down affected by the milking process) laid down for a mean of 9.8 h/d. Steps walked and delay in the dairy waiting to be milked were both significantly associated with lying time, but the effect was not large. A regression model accounting for the waiting time at the dairy, steps taken, cow age, and farm was used to investigate the relationship with daily lying time. For every 1,000 steps, lying time reduced by 0.49 h; however, the number of steps explained only 1% of the variation in lying time. For every hour increase in waiting time at the dairy, lying decreased by approximately 14 min, but this explained only 14% of the variation in lying. We concluded that milking time durations of 2 to 4 h, common in large Australian pasture-based dairy herds, did not significantly affect the time budget for lying of individual cows in our study herds. Whereas the effect of long milking times does not appear to be a major risk to animal welfare in terms of lying time, the effect on cow health and production warrants further investigation.     

Effect of automatic milking systems on milk yield in a hot environment

A comparative study was performed to evaluate differences in milk yield between an automatic milking system (AMS) and a conventional herringbone milking parlor system. Two herds of Italian-Friesian cows were reared in the same barn, located in the Po Valley in northern Italy. Twenty-five primiparous cows and 10 multiparous cows were milked with an AMS, while at the same time 29 primiparous and 9 multiparous were milked twice daily in a milking parlor on the other side of the barn. A selection gate allowed cows to access the AMS only if the interval from last milking was >5 h. Multiparous cows in the AMS yielded more milk than multiparous cows in the milking parlor (34.2 ± 0.7 vs. 29.4 ± 0.6 kg/d). There was no difference in milk yield between primiparous cows in the AMS and in the milking parlor (28.9 ± 0.4 vs. 28.8 ± 0.3 kg/d). Milking frequency in the AMS was significantly higher in primiparous (2.8 ± 0.03) than in multiparous cows (2.5 ± 0.04). The hot season negatively affected milk yield; the milk yield reduction was higher for cows milked with the AMS (−4.5 ± 0.6 kg/d) than in the milking parlor (−3.0 ± 0.8 kg/d). In the AMS, milking frequency decreased during the hot season in primiparous cows (−0.3 ± 0.1). We concluded that a positive AMS effect on milk yield is possible, but that steps must be taken to alleviate the discomfort involved with attracting cows to the AMS.     

Stress responses during milking; comparing conventional and automatic milking in primiparous dairy cows

A comparative study was performed to evaluate the differences in behavioral and physiological stress responses during milking between cows that were milked by an automated milking system (AM-cows) and cows that were milked in a conventional tandem parlor (TM-cows). In a randomized design, 36 primiparous Holstein-Friesian dairy cows were observed and blood sampled (1-min intervals) individually during milking. AM-cows spent less time standing with their heads outside the feeding trough than TM-cows and had a lower heart rate. In addition, AM-cows had lower maximum plasma adrenaline and noradrenaline concentrations during milking. No differences were found in the number of steps. After tactile stimulation of the teats either by hand or by the cleaning brush, mean oxytocin concentrations did not differ. In AM-cows, however, elevated oxytocin levels were prolonged at the end of milking. Averaged over the first five blood samples, AM-cows tended to have higher plasma cortisol concentrations than TM-cows, but median fecal concentrations of the cortisol metabolite dioxoandrostane were comparable. Maximum quarter milk flow, maximum udder milk flow and residual milk as a percentage of the total milk volume was comparable. From this study it is concluded that behavioral and physiological responses, both in automatically and in conventionally milked cows, were relatively low and were typical for cows being milked. We therefore conclude that, as far as the welfare of the dairy cow during milking is concerned, automatic milking and conventional milking are equally acceptable.     

Thermodynamics of standing and lying behavior in lactating dairy cows in freestall and parlor holding pens during conditions of heat stress

Heat load is a challenge for high-producing dairy cows, with adverse consequences on production, reproduction, and welfare. The objectives of this observational study in 2 commercial dairy herds were to determine the effects of environmental heat stress on standing and lying behavior, to monitor the changes in core body temperature (CBT) of cows during lying and standing bouts, and to compare changes in CBT during standing bouts in freestall pens versus standing in holding pens. High-producing cows were selected for data collection over a period of 6 d of increasing heat stress during a heat wave to which they were not acclimated. A total of 20 cows were fitted with leg accelerometers that recorded lying behavior and with vaginal temperature loggers that recorded CBT. These data were recorded at 30-s intervals. Time in the parlor holding pen was calculated from automated parlor software that recorded milking unit attachment and removal times. Mean daily temperature–humidity index in the pens increased from 68.5 to 79.0 during the 6-d trial, whereas mean daily lying time decreased from 9.5 to 6.2 h/d. The mean number of lying bouts per day remained similar at 11.1 to 12.2, but duration of lying bouts decreased from a high of 49.7 min on the coolest day to 32.8 min on the hottest day. During lying bouts, CBT increased at a mean rate of 0.50°C/h. In contrast, CBT changed at a mean rate of −0.25°C/h when standing in the freestall pens and only −0.09°C/h when standing in the milking-center holding pens. Explanatory models for the CBT at which cows ended either standing or lying bouts were derived from 6 selected lying bouts and 3 selected standing bouts for each cow on each day. The CBT at which a cow ended a lying bout was positively related to CBT and temperature–humidity index at the start of the bout, bout duration, and rate of CBT change during the bout. The CBT at which a cow ended a standing bout was negatively related to bout duration and positively related to start CBT, start temperature–humidity index, and rate of CBT change. Insights into the thermodynamics of standing and lying behavior in dairy cows during periods of heat stress provided by this study may contribute to the development of more effective strategies to mitigate heat load in dairy cattle.     

Lactating dairy cows adapt quickly to being milked by an automatic milking system

Transitioning a dairy herd to an automatic milking system (AMS) from a conventional parlor system may be stressful for the cow, as many changes occur during this process. Chronic stress may affect the welfare of the cow, and acute stress during milking can decrease milk yield. Therefore, it is important to quantify if and how long stress during adaptation to an AMS might persist. Seventy-seven cows with acceptable udder and teat conformation that would not interfere with adaptation to the AMS and that were lactating n = 18, early [0 to 100 d in milk (DIM)]; n = 27, mid (100 to 200 DIM); and n = 32, late (200+ DIM) for the full duration of the project were chosen for observation. All cows had been milked previously in a double-6 herringbone milking parlor. Four stress-related behaviors [step-kick behavior both before and after attachment of teat cups, elimination (urination and defecation instances), and vocalization] were recorded during milking by trained observers, whereas milk yield was automatically recorded by the AMS. Data were collected for 24-h periods beginning on the day the cows transitioned to milking in the AMS (d 0), and on d 1, 2, 4, 8, 16, and 32 thereafter. Instances of elimination and vocalization were greater on d 0 compared with all other days (elimination: d 0 = 3.1 ± 0.09, d 1 = 0.6 ± 0.07, and 0 ± 0 instances thereafter; vocalization: d 0 = 1.7 ± 0.07, d 1 = 0.05 ± 0.04, and 0 ± 0 instances thereafter). Milk yield increased between d 0 (18.3 ± 1.7 kg) and d 1 (30.9 ± 1.7 kg). Primiparous cows (n=28) were more likely than multiparous cows (n = 49) to display step-kick behaviors both before (8.3 ± 2.5; 5.5 ± 0.6, respectively) and after (15.6 ± 2.4; 13.3 ± 1.3, respectively) teat cup attachment during milking. Eight days after introducing the cows to the AMS, over 60% of the herd was milking voluntarily and 95% of the herd was milking voluntarily within a month, which suggests that cows did not find the AMS aversive. Greater elimination and vocalization behavior and lower milk yield on d 0 relative to subsequent days indicated initial stress and discomfort with the milking process in the new system; however, the cows appeared to adapt within 24h.     

Assessment of the current performance of grazing infrastructure across Irish dairy farms

The increased average Irish dairy herd size in a post-quota environment has put heightened pressure on grazing infrastructure. In a rotational grazing system, grazing infrastructure consists of the paddock system, which delineates the grazing areas into appropriately sized grazing parcels, and the roadway network, which connects these paddocks to the milking parlor. Where herd size has increased without corresponding adaptations to the infrastructure, farm management and roadway network performance has been affected. The links between suboptimal grazing infrastructure and roadway network efficiency are poorly understood and not widely documented. The aims of this study were to (1) analyze the effect of herd expansion and paddock size on pasture allocations per paddock, (2) identify the factors that affect the total distance walked per year, and (3) create a metric to compare the efficiency of roadway networks across farms of varying grazing platforms. A sample population of 135 Irish dairy farms with a median herd size of 150 cows was used for this analysis. Herds were split into the following 5 categories: <100 cows, 100 to 149 cows, 150 to 199 cows, 200 to 249 cows, and ≥250 cows. Herds with ≥250 cows had a greater number of paddocks per farm and rotated around the grazing paddocks more frequently, with 46% of paddocks only suitable for 12 h allocations relative to herd size, compared with just 10% to 27% of paddocks for herds with <100 cows to herds with 200–249 cows. When predicting the total distance walked per year on each study farm, the mean distance from a paddock to the milking parlor was the strongest indicator (R² = 0.8247). Other metrics, such as herd size, have failed to account for the location of the milking parlor relative to the grazing platform. The creation of the relative mean distance from a paddock to milking parlor (RMDMP) metric allowed the calculation of a farm's roadway network efficiency for moving the herd between paddocks and the milking parlor. The analyzed farms increased their efficiency in terms of RMDMP (0.34–40.74%) as they increased herd size post quota. However, the position of new additional paddocks relative to the milking parlor substantially affected their RMDMP.     

Diurnal temperature patterns of early lactating cows with milking parlor cooling

Ten cows in early stages of lactation (less than 100 days postpartum) were used to test the effect of sprinkler/fan cooling on vaginal temperature patterns. Cows were assigned to two groups matched according to milk production. The trial was divided into three periods: period 1, when one group was treated and the other group was not, period 2, when neither group was treated, and period 3, when treatment was switched from period 1 between groups. Treatment consisted of forced air misting in a premilking holding pen, fan cooling during milking, and forced air-sprinkling in a postmilking holding area. Weather conditions were measured by dry bulb, wet bulb, and black globe temperatures. Black globe temperatures in pre- and postmilking holding areas were used to estimate treatment magnitude. All measures were obtained through radiotelemetry at 15-min intervals for 31 days. Animals were milked twice a day. Animals spent an average of 140 min in treatment at each milking. In both morning and afternoon milking, treatment caused a transient increase of body temperature. However, this was followed in the afternoon by low vaginal temperatures for 1 to 2 h beyond treatment with lower temperatures throughout the day.     

Reproductive Management of Dairy Cows in High Milk-Producing Herds

Challenges limiting reproductive efficiency of high milk-producing cows include interrelationships among body condition, dry matter intake, transition from the dry period to lactation, onset of normal estrous cycles, detection of estrus, and embryonic survival. Attention is required to details associated with diet formulation; feed bunk management; cow comfort in free stalls, holding pen, and milking parlor during extremes of temperature and humidity; proper hoof care; milking management and mastitis prevention; control of ovulation and estrus; and early nonpregnancy diagnosis. Intensive management of transition cows should involve monitoring key metabolic markers using hand-held devices. This should allow early detection of illnesses that can be followed by proven interventions to alleviate their residual effects. Body condition should be monitored more closely to reduce dry cow and transition problems and prevent prolonged anestrus by maximizing early postpartum dry matter intakes. Cow comfort should be monitored more closely to minimize standing time for milking, maximize standing time for estrus and feed intake, and maximize resting time for rumination and more efficient milk synthesis. Estrus may be detected using automated techniques such as pedometry, rump-mounted pressure-sensitive radio-telemetric devices, and in-line parlor tests for milk progesterone or estrogen. More highly fertile heifers may be impregnated using sexed semen, sexed embryos, or clones to provide more replacement heifers because of declining fertility of lactating cows. Strategies to impregnate high-producing cows will require more ovulation control before first and subsequent services without detection of estrus. Because of high rates of embryonic death, more pregnancies may be achieved by using sexed or cloned embryos. Many reproductive technologies used today, including programmed breeding, will be refined and incorporated into the management of cows on fewer dairy farms with more cows per farm. Despite trends for longer lactations associated with bST and lesser pregnancy rates, renewed lactations following parturition will continue to be essential for herd longevity of cows.     

Comparison of modeled sampling strategies for estimation of dairy herd lameness prevalence and cow-level variables associated with lameness

Monitoring herd lameness prevalence has utility for dairy producers and veterinarians in their efforts to reduce lameness, for animal welfare assessment programs, and for researchers. Locomotion scoring is a method used to quantify lameness and calculate prevalence. Because of the time necessary to locomotion score each cow in large dairy herds, a sampling strategy to determine herd lameness prevalence that allows scoring of fewer cows would be useful. Such a sampling strategy must be validated for accuracy compared with the lameness prevalence when all cows in a herd are locomotion scored. The purpose of this study was to assess 3 previously suggested methods of estimating lameness prevalence by strategic sampling of dairy herds. Sampling strategies tested included (1) sampling a calculated number of cows in the middle third of the milking parlor exit order for each pen, (2) sampling a calculated number of cows weighted across pens and distributed evenly within each pen, and (3) sampling all cows in the high production, low production, and hospital pens. Lactating cows on 5 dairy farms in Washington and Oregon (n = 4,422) were locomotion scored using a 5-point scale to determine herd-level lameness prevalence (percentage with locomotion score ≥3). Milking parlor exit order, order in headlocks at the feed bunk within each pen, and breed were recorded for each cow. The number of days in lactation, milk production, and parity were collected from farm computer records. Pen grouping strategy for each farm was obtained by interview with farm management. Sampling strategies were modeled using the locomotion score data set for each herd. Estimates of lameness prevalence obtained from the milking parlor exit order sample and the sample distributed across pens were within 5 percentage points of the whole herd prevalence. The third strategy estimated the lameness prevalence within 5 percentage points on 4 farms, but overestimated prevalence on 1 farm. Pen-level prevalence obtained by locomotion score of all cows in the pen was variable and not reliably predictive of herd-level prevalence. Cows of Holstein breed, parity >1, and exiting the milking parlor in the last 20% of the pen had greater odds of lameness compared with other breeds, parities, and milking parlor exit order groups in a multivariate analysis. This study indicates that the sampling strategies using the middle of milking parlor exit order and a calculated sample distributed across the herd may be used to obtain an estimate of herd lameness prevalence.     

Effects of milking stall dimensions on behavior of dairy cows during milking in different milking parlor types

Dairy cow body size has increased over time because of breeding selection for higher milk yield, but milking stall dimensions have never been adjusted and are based on the practical experience of milking-machine manufacturers and advisory institutions. Narrow, limited milking stall dimensions might lead to behavioral changes during milking due to lack of comfort. The aim of this study was to examine the current space allowance in milking stalls on dairy farms and assess the effect of space allowance on cow behavior during milking. On 15 Swiss dairy farms, we measured clear milking stall dimensions and cow body dimensions. We calculated space ratios for length (SR_length) and width (SR_width) by dividing the milking stall length or width by cow body length or belly width, respectively. When the space ratio was >1, we assumed that the body length or width of cow was smaller than the milking stall length or width. On each farm, 10 healthy cows were chosen for behavioral observation during 1 evening milking. We recorded rumination, elimination, and latency to enter the milking stall by direct observation. Hind leg activity was recorded using acceleration loggers. Data were analyzed using general linear mixed-effects models with farm as a random effect. Due to a strong collinearity between SR_width and SR_length, we chose SR_length for further analysis, because it is based on skeletal characteristics. The SR_length was smallest in side-by-side parlors (1.07 ± 0.01) and largest in tandem parlors (1.18 ± 0.01). More cows had a tendency to ruminate with increasing SR_length (odds ratio: 1.8). None of hind leg activity, maximum peaks of hind leg accelerations, or latency to enter the milking stall were significantly affected by SR_length. Latency to enter the milking stall was longer for group milking parlors (side-by-side: 44.0 ± 3.2 s; herringbone: 34.3 ± 2.9 s) than for tandem parlors (19.0 ± 2.7 s). Milking parlor type had no effect on hind leg activity, maximum peaks of hind leg accelerations or rumination. The SR_length affected rumination behavior to some extent, indicating that cow comfort was positively affected by larger milking stall length. Because cow comfort is important for good milking performance, further investigations of milking stall dimensions for cow comfort and thus welfare are needed. Furthermore, the results showed that parlor type affected cow behavior, irrespective of SR_length, making future research necessary to identify the factors leading to this effect of parlor type.     

Lower working heights decrease contraction intensity of shoulder muscles in a herringbone 30° milking parlor

Musculoskeletal disorders have been a main concern in milkers for many years. To improve posture, a formula was developed in a previous study to calculate ergonomically optimal working heights for various milking parlor types. However, the working height recommendations based on the formula for the herringbone 30° parlor were broad. To clarify the recommendations for the optimal working height, we investigated the effect of working height on upper limb and shoulder muscle contraction intensities. We evaluated 60 milking cluster attachment procedures in a herringbone 30° milking parlor in 7 men and 9 women. Specifically, we examined the effect of working height on muscle contraction intensity of 4 arm and shoulder muscles bilaterally (flexor carpi ulnaris, biceps brachii, deltoideus anterior, and upper trapezius) by using surface electromyography. The working heights (low, medium, and high), which reflect the ratio of the subject's height to the height of the udder base, were used in the milking health formula to determine and fit individual depth of pits. Data were evaluated for each muscle and arm side in the functions holding and attaching. Statistical analysis was performed using linear mixed effects models, where muscle contraction intensity served as a target variable, whereas working height coefficient, sex, subject height, and repetition were treated as fixed effects, and repetition group nested in working height nested in subject was considered a random effect. Contraction intensities decreased with decreasing working height for the deltoideus anterior and upper trapezius, but not for the flexor carpi ulnaris or the biceps brachii muscles in both holding and attaching arm functions. We found that milking at a lower working height reduced muscle contraction intensities of the shoulder muscles. Women showed higher contraction intensities than men, whereas subject height had no effect. The study demonstrated that a lower working height decreased muscular load during milking. These lower working heights should be used within the recommendations made by the milking health formula for the herringbone 30°. Working heights could be adjusted effectively for milkers of varying body height. Future studies should therefore use the milking health formula as a tool to objectively compare and improve the accuracy of the working height coefficients.     

Influence of provision of concentrate at milking on voluntary cow traffic in a pasture-based automatic milking system

The success of an automatic milking system is generally reliant upon the voluntary movement of cows around the farm system and the correct management of incentives to achieve a targeted level of cow traffic. The present study investigated the effect of providing a small feed reward as an incentive at milking on the premilking voluntary waiting time of cows milked on a prototype robotic rotary in an Australian pasture-based dairy. The 2 treatments were “feed on” (concentrate offered at milking) and “feed off” (no concentrate offered at milking), with data from a single herd of 168 lactating dairy cows collected over 16 d. A survival analysis with time-varying covariates was used to model the voluntary waiting times of cows in the premilking yard. The median time cows spent waiting before milking was 129 min and after 4 h just over 70% of the cows had exited the yard (volunteered for milking). When feed was provided, cows were faster to exit the premilking yard (shorter time spent waiting) and waited just over half the time (0.53×) they did during the “feed off” treatment. Heifers exited the premilking yard more rapidly than cows in later lactations, with older cows spending at least 1.40 times longer in the yard before milking. Average daily milk yield along with stage of lactation and fetching cows from the paddock also influenced cow traffic in the premilking yard. As the number of cows in the premilking yard increased, voluntary waiting time also increased. At a queue length of 20 or more cows, the negative effect on waiting time of an additional cow entering the yard was less than that when fewer than 20 cows were present. Results demonstrated that feeding a small reward on the robotic rotary platform can reduce the time cows spend in the premilking yard, leading to a potential reduction in the risk of congestion at the dairy, particularly during times of high demand. Minimizing congestion will likely benefit multiple aspects of the voluntary milking operation, including a potential improvement in robot utilization, a reduction in unnecessary time spent off pasture by cows in the milking herd, promoting cow welfare through reducing the risk of lameness, and enhancing productivity. Targeting strategies to minimize queue length to less than the threshold length, which in this study was 20 cows, could result in reduced time spent in the premilking yard.     

Manageable risk factors associated with bacterial and coliform counts in unpasteurized bulk milk in Flemish dairy herds

Associations between herd management practices and both bacterial counts (BC) and coliform counts (CC) from 254 and 242 dairy herds in Flanders (Belgium), respectively, were studied. Data were analyzed using multivariable, multilevel linear regression analysis, allowing variance components analyses. Both BC and CC fluctuated throughout the year, although the milk quality parameters followed an opposite pattern. Bacterial count values decreased with each increase of the cleaning frequency of the cubicles (once per week, once per day, twice per day, or more than twice per day) between January and March. Herds with a conventional milking parlor had substantially lower BC than herds where the cows were milked using an automatic milking system. Lower BC were observed when the milking parlor was equipped with an automatic cluster removal system, when premilking teat disinfection was applied, when the dry cows were supplemented with a mix of minerals and vitamins, and when the teats were prepared either first wet and dried or via an automatic milking system. Milking cows with a high-pipeline milking parlor setup or with an automatic milking system was associated with substantially higher CC values. Herds where prepartum heifers were often treated with antimicrobials before calving had a lower CC than farms where heifers were either not or only rarely treated. Most variation in BC and CC resided at the herd level rather than at the observation level, indicating that management is important in the control of both BC and CC. Still, only a small proportion of the total variance was explained by factors capturing information related to the milking, herd health, and dry cow management, which suggests that the bacteriological milk quality and, in particular, CC is primarily driven by other factors than the ones included in this study.