Temporal feed restriction and overstocking increase competition for feed by dairy cattle

Dairy cows are often overstocked. Some managers are now using “slick bunk” (i.e., feeding for 0% orts) management to save on feed costs, but this reduces the time that cows have access to feed. Both practices may increase competition and affect feeding behavior in dairy cows. The aim was to determine the effects of temporal and spatial restrictions on the feeding and competitive behavior of group-housed cows. Treatments were 2 levels of stocking (2:1 versus 1:1 cows:feed bin) and 2 levels of feed access time (14 versus 24 h/d access). Eight groups (each of 6 cows) were tested on each of the 4 treatment combinations for 1 wk, with treatment order assigned using a replicated 4 × 4 Latin square design. Dry matter intake (DMI), feeding time, and feeding rate were measured for the last 4 d of each week, and data were summarized daily and for the 2-h period immediately after the morning feeding. Displacements were recorded for 2 h after the delivery of morning feed (peak feeding period) and 2 h following the afternoon milking. The DMI did not decline when temporal access was restricted (27.0 vs. 25.7 ± 0.5 kg/d), and was not affected by overstocking (26.4 ± 1.9, mean ± SD). Cows with restricted temporal access spent less time feeding (190.9 vs. 207.9 ± 6.1 min). Overstocked cows that were temporally restricted had greater feeding rates during the day (156 vs. 137 ± 4 g/min) and especially during the peak feeding period (175 vs. 146 ± 4 g/min) compared with cows that were not restricted. In the peak feeding period, overstocked cows had reduced DMI (3.0 vs. 3.4 ± 0.1 kg/h) and feeding times (20.8 vs. 25.8 ± 1.0 min/h) and increased feeding rates (161 vs. 138 ± 4 g/min). Cows with restricted temporal access had greater DMI (3.9 vs. 2.6 ± 0.2 kg/h) and time spent feeding (27.3 vs. 19.2 ± 1.3 min/h) during the peak feeding period compared with cows that had continuous access to feed. Restricting temporal access in conjunction with overstocking resulted in the greatest increase in daily displacements (15.0 vs. 3.8 ± 1.4 displacements/d); the majority of these occurred during the peak feeding period. Adequate space and time to access feed is essential to minimize feed bunk competition in indoor group housing systems.     

Correlated changes in behavioral indicators of lameness in dairy cows following hoof trimming

Cow gait, walking speed, time spent lying down, and distribution of weight among legs when standing during the week before and up to 5 wk after hoof trimming were assessed in 48 lactating Holstein cows housed in freestall pens to examine how changes in gait score following hoof trimming were correlated with other behavioral changes. Gait responses to hoof trimming varied between cows, with the majority showing no change or an increase in gait score. Walking speed was reduced after hoof trimming, and this decrease was maintained during the following 4 wk. The change in walking speed following hoof trimming negatively correlated with the change in gait (r = −0.33). Before hoof trimming, lame cows showed a greater standard deviation of the weight applied to the rear legs (38.4 vs. 27.2; standard error of the difference = 4.6). After hoof trimming, lame cows showed a quadratic increase in the standard deviation of the weight applied to the rear legs and the rear leg weight ratio, whereas no time trend existed for nonlame cows. The change in gait following hoof trimming was negatively correlated with the change in leg weight ratio (r = −0.44). Before hoof trimming, lame cows spent more time lying down each day than nonlame cows (801.7 vs. 731.7 min/d; standard error of the difference = 29.7). Both lame and nonlame cows increased the time they spent each day lying down after hoof trimming, and daily lying time remained higher for up to 5 wk after hoof trimming. The change in time spent lying down after hoof trimming was correlated with the change in gait (r = 0.30) and the change in leg weight ratio (r = −0.47). Using automated methods of lameness detection shows promise as a way of continuously monitoring animals to detect changes in behavior associated with the onset of or recovery from lameness.     

Rumination and its relationship to feeding and lying behavior in Holstein dairy cows

The objective of this study was to describe the relationship between rumination and feeding and lying behavior in dairy cows. Rumination time was monitored electronically using HR-Tags (SCR Engineers Ltd., Netanya, Israel). Feeding time and dry matter intake (DMI) were monitored using Insentec feed bins (Insentec BV, Marknesse, the Netherlands). All measures were collected in 2-h periods for 42 mature Holstein cows for a minimum of 9 d in the early dry period. Pearson correlation was used to describe associations, among 2-h periods within cow, first examining the relationship within a single period, and then modeling how this relationship changes when a lag of 2, 4, or 6h was imposed. Periods when cows spent more time ruminating were associated with lower feeding times and lower DMI (r = -0.71 and r = -0.72, respectively), likely because cows were unable to feed and ruminate simultaneously. The correlations with rumination time changed from negative to positive when lags of 2, 4, and 6h were modeled (r = -0.09, 0.24, and 0.15, and r = -0.16, 0.23, and 0.17 for feeding time and DMI at lags of 2, 4, and 6h, respectively). These results indicate that following periods of high feeding times and intakes, cows spent more time ruminating. This relationship peaks at approximately 4h after feeding. Periods of rumination were also associated with time spent lying down. Cows that spent more time ruminating per day, spent less time feeding (r = -0.34) and rumination times did not relate to DMI (r = 0.11). These data indicate that rumination time can be used to estimate within-cow variation in feeding behavior and intake, but daily summaries of rumination behavior are a poor indicator of DMI.     

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 (R² ≥ 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.     

Effect of analgesia during hoof trimming on gait, weight distribution, and activity of dairy cattle

Sixty-six lactating cows were either injected with flunixin meglumine (2.2 mg/kg of BW) immediately before hoof trimming (n = 28), injected with a saline solution immediately before hoof trimming (n = 28), or injected with a saline solution immediately before sham hoof trimming (control; n = 10). Gait scores, time spent lying down, frequency of steps, and how cows distributed their weight among their legs when standing before, during, and after injections were measured to assess whether automated measures of activity and weight distribution can detect lameness and the effects of pain mitigation during hoof trimming. The overall gait score was positively correlated with the variability of the weight applied the rear legs (r = 0.32) and negatively correlated with the rear leg weight ratio (LWR; r = −0.52) and the frequency of steps (r = −0.43). The rear LWR was the best predictor of cows being lame (NRS >3), accounting for 27% of the variation in the likelihood of a cow being lame and 11% of the variation in the likelihood of a cow having an infectious hoof lesion. For each 5% increase in the rear LWR, the likelihood of being lame decreased by 30% (odds ratio = 0.71; 95% confidence interval = 0.56, 0.90) and the likelihood of being afflicted with an infectious hoof disease decreased by 20% (odds ratio = 0.81; 95% confidence interval = 0.67, 0.98). Neither hoof trimming nor a combination of hoof trimming and analgesia significantly affected gait score or any measure of weight distribution. Daily lying time increased during the 2 d following hoof trimming independently of the flunixin meglumine injection. However, this increase was not sustained for longer than 2 d when cows were injected with flunixin meglumine. Measures of weight shifting between legs while cows are standing and measures of activity show great potential as automated methods of detecting lameness and may also provide a tool for future evaluation of lameness therapies, such as hoof trimming and pain mitigation.     

Automated methods for detecting lameness and measuring analgesia in dairy cattle

The objective was to assess gait, automated measures of weight distribution among the legs, and daily activity as methods for detecting lameness in dairy cows and measuring pain mitigation by nonsteroidal antiinflammatory drugs. Fifty-seven lactating cows (28 of which were lame) were injected twice with ketoprofen (3.0 mg/kg i.m.) or isotonic saline solution. Gait scores (numerical rating system, NRS), time spent lying down, frequency of steps, and weight distribution among legs when standing before, during, and after injections were measured to assess whether automated measures of activity can detect lameness and the effect of analgesic drugs in cows. Lame cows (NRS >3) shifted weight between contralateral legs more often (SD of the weight applied: 31.1 ± 2.1 vs. 24.5 ± 1.9 kg), had a greater asymmetry in the weight applied to the rear legs (leg weight ratio = 0.78 ± 0.02 vs. 0.87 ± 0.02), had longer lying bouts (94.0 ± 4.9 vs. 78.2 ± 5.8 min), and walked slower (1.28 ± 0.3 vs. 1.42 ± 0.3 m/s) than nonlame cows. Variability over time (SD) of the weight applied to the rear legs was the most accurate predictor of whether a cow was lame or not (area under the curve = 0.71). The SD of the weight applied to the rear legs decreased on the days when ketoprofen was given compared with the day before and after (18 and 12% decrease for lame and nonlame cows, respectively). Ketoprofen did not affect any other measure. Measures of weight shifting between legs while cows are standing have potential as an automated method of detecting lameness and analgesia.     

The association of serum metabolites with clinical disease during the transition period

The objective of this observational field study was to validate the relationship of serum concentrations of nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and calcium with disease in early lactation across different management systems. Fifty-five Holstein freestall dairy herds located across the United States and Canada were selected and visited weekly for blood sample collection from 2,365 cows. Only diseases that were consistently recorded across herds and blood samples collected before the disease occurred were considered. Metabolite concentrations in serum in wk −1 relative to calving were considered as predictors of retained placenta (RP) and metritis, and metabolite concentrations in serum in wk −1 and wk +1 relative to calving were considered as predictors of displaced abomasum (DA). For each disease, each metabolite, and week of sampling in the case of DA, a critical threshold was calculated based on the highest combined sensitivity and specificity and used to categorize the serum concentrations into high and low risk categories. Multivariable logistic regression models were built for each disease of interest and week of sampling, considering cow as the experimental unit and herd as a random effect. Cows with precalving serum NEFA concentrations ≥0.3 mEq/L were more likely to develop RP [odds ratio (OR) = 1.8; 95% confidence interval (CI) = 1.3 to 2.6] and metritis (OR = 1.8; 95% CI = 1.5 to 2.9) after calving than cows with lower NEFA concentrations. Precalving NEFA ≥0.5 mEq/L (OR = 2.4; 95% CI = 1.5 to 3.7), postcalving NEFA ≥1.0 mEq/L (OR = 2.7; 95% CI = 1.7 to 4.4), and postcalving calcium ≤2.2 mmol/L (OR = 3.1; 95% CI = 1.9 to 5.0) were associated with subsequent risk of DA. In conclusion, elevated serum NEFA concentrations within 1 wk before calving were associated with increased risk of RP, metritis, and DA after calving. Serum NEFA and calcium concentrations in the 2 wk around calving in combination were associated with the risk of DA.     

Short communication: The effects of experimentally induced Escherichia coli clinical mastitis on lying behavior of dairy cows

Clinical mastitis is a commonly occurring and economically important problem in the dairy industry. Researchers have suggested that changes in lying behavior could be useful as early indicators of cow discomfort and poor welfare. The objective of this study was to determine the associations between the onset of illness resulting from experimentally induced clinical mastitis and measures of lying behavior. Clinical mastitis was induced in 21 lactating dairy cows (parity=2.0±1.0, range=1 to 4; days in milk=61±18) by intramammary infusion of 25 or 100 μg of Escherichia coli lipopolysaccharide (LPS) into 1 uninfected mammary quarter. Lying behavior was monitored from 2 d before through 3 d after the LPS challenge by fitting each cow with a data logger. Calculated outcome measures were total lying time, lying time on the side of the intramammary infusion, number of lying bouts, and average lying bout duration. Cows spent less time lying down on the day of the challenge compared with the 2 d before (633.3 vs. 707.0 min/d; SE=29.6), particularly during the 4 to 7h following LPS infusion. However, no significant relationship was found between the mammary quarter challenged and cow preference for lying side throughout the episode of induced clinical mastitis. Given that lying is a high-priority behavior in dairy cows and that increased lying time is an adaptive sickness behavior to facilitate recovery, we infer that this reduction in lying time may present a concern for cows with clinical mastitis. Although additional studies with larger numbers of animals are needed, automated monitoring of lying behavior could be an important component of the on-farm early detection of health problems, such as mastitis, in the future.     

A 128×128 CMOS image sensor with analog memory forsynchronous image capture

A 128×128 CMOS imager that permits synchronous capture is presented. The sensor combines the best of CMOS imagers (low-power, random readout, nondestructive readout, single supply voltage...) and synchronous capture [available in high-end charge coupled device (CCD) imagers]. The key point in obtaining such characteristics is the separation of the photosensor and the storage element. Although some sensors with these characteristics have been reported, in this sensor, the storage capability has been brought a step further, having storage times of the order of tens of seconds, and being able to use the array itself as a random access memory (RAM). This could avoid the use of external RAM, making the system simpler, more compact, and of low-power consumption     

Short communication: Estimation of genetic parameters for gait in Canadian Holstein cows

Lameness is one of the most important welfare and economic problems in modern dairy herds. In addition to environmental factors, lameness is affected by genetics and thus, long-term improvement of lameness can be accomplished through genetic selection. The objective of the study was to estimate the genetic parameters of a validated gait score and specific gait attributes for Holstein cows from a university dairy research herd. Two hundred thirty-three cows were gait scored multiple times over time (n = 1,664 records) in different experiments using a 1-to-5 numerical rating system (NRS). One hundred seventy-two cows (n = 657 records) also had 6 gait attributes scored using a 100-unit continuous visual analog scale (back arch, head bob, tracking up, joint flexion, asymmetric gait, and reluctance to bear weight). Single-trait linear animal models were used to estimate the heritability of NRS and each gait attribute, whereas a multivariate linear animal model was used to estimate genetic correlations between traits. The NRS and the gait attributes deteriorated with parity, and the scores for NRS, back arch, joint flexion, and asymmetry of the steps increased rapidly in early lactation. The heritability estimate (±SE) for NRS was 0.09 ± 0.09. Four of the gait attributes (reluctance to bear weight, head bob, tracking up, and asymmetry of the steps) had higher heritability than NRS, ranging from 0.11 ± 0.13 to 0.42 ± 0.15, whereas back arch showed no genetic variation. However, the small sample of animals resulted in large standard error of the estimates. The genetic correlations between NRS and the gait attributes were > 0.70, whereas the genetic correlations among the different gait attributes ranged from 0.14 to 0.92. In conclusion, NRS and most gait attributes showed genetic variation, indicating the opportunity to improve gait through genetic selection. Some specific gait attributes were more heritable than NRS and were genetically correlated with NRS. Further research with a larger population is needed to assess whether specific gait attributes would be suitable candidate traits to consider in genetic evaluations in the future.