A history of lameness and low body condition score is associated with reduced digital cushion volume,measured by magnetic resonance imaging,in dairy cattle

Claw horn lesions (CHL) are the result of a failing of the functional anatomy of the hoof in dairy cows. The digital cushion is understood to be a vital structure in the prevention of CHL. Claw horn lesions have previously been shown to lead to pathological change to the pedal bone; however, their effects on the digital cushion are unknown. The primary aim of this study was to examine associations between the history of CHL through an animal's life and the structure of the digital cushion at slaughter using magnetic resonance imaging. The retrospective cohort study resulted in the scanning of 102 pairs of hindfeet, collected from adult Holstein dairy cows culled from a research herd, using a 3-Tesla research-grade magnetic resonance imaging scanner. Volume and fat measurements were calculated for each digital cushion within each claw from a modified Dixon Quant sequence. Animal-level variables were constructed around the animals' lactating lifetime, with lameness scores and body condition score collected at least every 2 wk. The combined volume of digital cushion in the lateral claws was used as the outcome variable in multivariable linear models. The volume of the digital cushion was negatively associated with the number of lameness events or CHL recorded. Furthermore, animals with body condition score >3, culled later in lactation, or of a greater body weight were more likely to have a higher volume of digital cushion in the lateral claws. We propose that the observations made in the current study are the effects of a range of factors broadly associated with genetic, developmental, and disease-related inputs. Our understanding of how we can select for genetically more robust animals and how we can precondition the hoof before first calving needs to be improved to reduce the risk of future CHL in adult dairy cattle. Furthermore, understanding optimal treatment regimens and their effect on hoof anatomy may reduce the recurrence of CHL in the current lactation and future lactations.     

Genetic parameters and genome-wide association study of digital cushion thickness in Holstein cows

The digital cushion is linked to the development of claw horn lesions (CHL) in dairy cattle. The objectives of this study were to (1) estimate genetic parameters for digital cushion thickness (DCT), (2) estimate the genetic correlation between DCT and CHL, and (3) identify candidate genes associated with DCT. A cohort of 2,352 Holstein dairy cows were prospectively enrolled on 4 farms and assessed at 4 time points: before calving, immediately after calving, in early lactation, and in late lactation. At each time point, CHL was recorded by veterinary surgeons, and ultrasonographic images of the digital cushion were stored and retrospectively measured at 2 anatomical locations. Animals were genotyped and pedigree details extracted from the national database. Genetic parameters were estimated following a single-step approach implemented in AIREMLF90. Four traits were analyzed: the 2 DCT measurements, sole lesions (sole hemorrhage and sole ulcers), and white line lesions. All traits were analyzed with univariate linear mixed models; bivariate models were fit to estimate the genetic correlation between traits within and between time points. Single-marker and window-based genome-wide association analyses of DCT traits were conducted at each time point; candidate genes were mapped near (<0.2 Mb) or within the genomic markers or windows with the largest effects. Heritability estimates of DCT ranged from 0.14 to 0.44 depending on the location of DCT measurement and assessment time point. The genetic correlation between DCT and sole lesions was generally negative, notably between DCT immediately after calving and sole lesions in early or late lactation, and between DCT in early or late lactation and sole lesion severity in early or late lactation. Digital cushion thickness was not genetically correlated with white line lesions. A polygenic background to DCT was found; genes associated with inflammation, fat metabolism, and bone development were mapped near or within the top markers and windows. The moderate heritability of DCT provides an opportunity to use selective breeding to change DCT in a population. The negative genetic correlation between DCT and sole lesions at different stages of production lends support to current hypotheses of sole lesion pathogenesis. Highlighted candidate genes provide information regarding the complex genetic background of DCT in Holstein cows, but further studies are needed to explore and corroborate these findings.     

Association of digital cushion thickness with sole temperature measured with the use of infrared thermography

The main objective of this study was to investigate the association between digital cushion thickness and sole temperature measured by infrared thermography. Data were collected from 216 lactating Holstein cows at 4 to 10 d in milk (DIM). Cows were locomotion scored and sole temperature was measured after claw trimming (a minimum delay of 3 min was allowed for the hoof to cool) using an infrared thermography camera. Temperature was measured at the typical ulcer site of the lateral digit of the left hind foot. Immediately after the thermographic image was obtained, the thickness of the digital cushion was measured by ultrasonography. Rumen fluid samples were collected with a stomach tube and sample pH was measured immediately after collection. Additionally, a blood sample was obtained and used for measurements of serum concentrations of β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and haptoglobin. To evaluate the associations of digital cushion thickness with sole temperature, a linear regression model was built using the GLIMMIX procedure in SAS software (SAS Institute Inc., Cary, NC). Sole temperature was the response variable, and digital cushion thickness quartiles, locomotion score group, rumen fluid pH, rumen fluid sample volume, environmental temperature, age in days, and serum levels of NEFA, BHBA, and haptoglobin were fitted in the model. Only significant variables were retained in the final model. Simple linear regression scatter plots were used to illustrate associations between sole temperature (measured by infrared thermography at the typical ulcer site) and environmental temperature and between NEFA and BHBA serum levels and haptoglobin. One-way ANOVA was used to compare rumen fluid pH for different locomotion score groups and for different digital cushion quartiles. Results from the multivariable linear regression model showed that sole temperature increased as locomotion scores increased and decreased as digital cushion thickness increased. These results were adjusted for environmental temperature, which was significantly associated with sole temperature. Serum levels of NEFA, BHBA, and haptoglobin were not associated with sole temperature. However, significant correlations existed between serum levels of NEFA and haptoglobin and between serum levels of BHBA and haptoglobin. Rumen fluid pH was not associated with either locomotion score or digital cushion thickness. In conclusion, we show here that digital cushion thickness was associated with sole temperature in cows at 4 to 10 DIM.     

Morphology,adipocyte size,and fatty acid analysis of dairy cattle digital cushions,and the effect of body condition score and age

The digital cushion is an essential part of maintaining a healthy foot, working to dissipate foot strike and body weight forces and lameness from claw horn disruption lesions. Despite the importance of the digital cushion, little is known about the basic anatomy, adipocyte morphology, and fatty acid composition in relation to age, limb position, and body condition score. In total, 60 claws (from 17 cows) were selected and collected from a herd, ensuring that body condition score data and computed micro-tomography were known for each animal. Digital cushion tissue underwent histological staining combined with stereology, systematic random sampling, and cell morphology analysis, in addition to lipid extraction followed by fatty acid analysis. The results describe digital cushion architecture and adipocyte sizes. Adipocyte size was similar across all 4 claws (distal left lateral and medial and distal right lateral and medial) and across the ages (aged 2–7 yr); however, animals with body condition score of 3.00 or more at slaughter had a significantly increased cell size in comparison to those with a score of less than 2.50. Of 37 fatty acid methyl esters identified, 5 differed between either the body condition score or different age groups. C10:0 capric acid, C14:0 myristic acid, C15:0 pentadecanoic acid, and C20:0 arachidic acid percentages were all lesser in lower body condition score cows, whereas C22:1n-9 erucic acid measurements were lesser in younger cows. Saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acid percentages were not altered in the different claws, ages, or body condition score groups. Triglyceride quantities did not differ for claw position or age but had decreased quantities in lower body condition score animals. Digital cushion anatomy, cellular morphology, and fatty acid composition have been described in general and also in animals with differing ages, body condition scores, and in the differing claws. Understanding fat deposition, mobilization, and composition are essential in not only understanding the roles that the digital cushion plays but also in preventing disorders and maintaining cattle health and welfare.     

Associations among patterns in daily body weight, body condition scoring, and reproductive performance in high-producing dairy cows

The objective was to investigate the associations between body condition scores (BCS) and daily body weight (BW) in the first 150 d of lactation (DIM) and reproductive performance in high-producing dairy cows. Data included automated daily BW measurements and BCS of 2,020 Israeli Holstein cows from 7 commercial farms. Individual BW series were smoothed using penalized cubic splines, and variables representing BW patterns were generated. The presence of 7- and 21-d cycles in BW was determined using time-series analysis. Associations between BW and BCS and conception at first artificial insemination (AI) were analyzed using generalized estimating equations. Multivariate survival analysis was used for associations between BW and BCS and the calving-to-first AI interval, first AI-to-conception interval, and calving-to-conception interval. First-parity cows that lost ≥12% and second-parity cows that lost ≥15% of their BW from calving to nadir BW were less likely to conceive at first AI. Cows without 7-d cycles in BW were 1.48 times more likely to conceive at first AI relative to cows with 7-d cycles. The odds of conceiving at first AI increased by 53% for each additional unit in BCS from 40 to 60 DIM. In the multivariate survival analysis, a BCS of ≤2.5 between 40 and 60 DIM, the percentage of BW lost from calving to nadir BW, and a BW loss of ≥7% from calving to 10 DIM were associated with reduced reproductive performance. The presence of 21-d cycles in BW was associated with high reproductive performance in first-parity [odds ratio (OR) = 1.18] and second-parity cows (OR = 1.22). The presence of 7-d cycles in BW was associated with low reproductive performance in first-parity cows (OR = 0.77), but not in older cows. Based on previous findings and on the associations found in this study, we postulate that 21-d cycles are probably related to the sexual cycle and could be used as a proxy for assessing ovarian activity. Variables representing relative BW loss (%) were better predictors for impaired reproductive performance than those representing absolute BW loss (kg) and may be more suitable for estimating individual adaptation to negative energy balance in herds for which automated daily BW is available.     

Short communication: Genetic characterization of digital cushion thickness

Dairy cow lameness is a serious animal welfare issue. It is also a significant cause of economic losses, reducing reproductive efficiency and milk production and increasing culling rates. The digital cushion is a complex structure composed mostly of adipose tissue located underneath the distal phalanx and has recently been phenotypically associated with incidence of claw horn disruption lesions (CHDL); namely, sole ulcers and white line disease. The objective of this study was to characterize digital cushion thickness genetically and to investigate its association with body condition score (BCS), locomotion score (LOCO), CHDL, and milk production. Data were collected from 1 large closely monitored commercial dairy farm located in upstate New York; 923 dairy cows were used. Before trimming, the following data were collected by a member of the research team: BCS, cow height measurement, and LOCO. Presence or not of CHDL (sole ulcer or white line disease, or both) was recorded at trimming. Immediately after the cows were hoof trimmed, they underwent digital sonographic B-mode examination for the measurement of digital cushion thickness. Factors such as parity number, stage of lactation, calving date, mature-equivalent 305-d milk yield (ME305MY), and pedigree information were obtained from the farm’s dairy management software (DairyCOMP 305; Valley Agricultural Software, Tulare, CA). Univariate animal models were used to obtain variance component estimations for each studied trait (CHDL, BCS, digital cushion thickness average, LOCO, height, and ME305MY) and a 6-variate analysis was conducted to estimate the genetic, residual, and phenotypic correlations between the studied traits. The heritability estimate of DCTA was 0.33 ± 0.09, whereas a statistically significant genetic correlation was estimated between DCTA and CHDL (−0.60 ± 0.29). Of the other genetic correlations, significant estimates were derived for BCS with LOCO (−0.49 ± 0.19) and ME305MY (−0.48 ± 0.20). Digital cushion thickness is moderately heritable and genetically strongly correlated with CHDL.     

The effect of claw horn disruption lesions and body condition score at dry-off on survivability, reproductive performance, and milk production in the subsequent lactation

The objective of this study was to evaluate the effects of claw horn disruption lesions (CHDL; sole ulcers and white line disease) and body condition score (BCS) at dry-off on survivability, milk production, and reproductive performance during the subsequent lactation. An observational prospective cohort study was conducted on a large commercial dairy in Cayuga County, New York, from September 2008 until January 2009. A total of 573 cows enrolled at dry-off were scored for body condition and hoof trimmed; digits were visually inspected for the presence of CHDL. The BCS data were recategorized into a 3-level variable BCS group (BCSG), with cows with BCS <3 placed in BCSG 1 (n = 113), cows with BCS = 3 placed in BCSG 2 (n = 254), and cows with BCS >3 placed in BCSG 3 (n = 206). Cows in BCSG 2 were 1.35 and 1.02 times more likely to conceive than cows in BCSG 1 and 3, respectively. The cull/death hazard for BCSG 1 cows was 1.55 and 1.47 times higher than for cows in BCSG 2 and BCSG 3, respectively. Milk yield for cows in BCSG 2 (44.6 kg/d, 95% CI 43.4-45.8) was significantly greater than that for cows in BCSG 1 (41.5 kg/d, 95% CI 39.8-43.3). Cows with previous lactation days open ≤91 had 1.6 times higher odds of being classified into BCSG 1 at dry-off; cows with previous lactation mature-equivalent 305-d milk >14,054 kg had a similar 1.6 times higher odds of being classified into BCSG 1. Claw horn disruption lesions were found in 24.4% of the cows (n = 140) at dry-off. Cows without CHDL were 1.4 times more likely to conceive than cows with CHDL. Additionally, lesion cows were 1.7 times more likely to die or be culled than nonlesion cows. Absence of CHDL did not have a significant effect on milk yield. These findings highlight the importance of claw health and BCS at the end of lactation on future survival and performance.     

Associations between housing and management practices and the prevalence of lameness,hock lesions,and thin cows on US dairy operations

The objective of this study was to determine the association among different housing and management practices on the prevalence of lameness, hock lesions, and thin cows on US dairy operations. This study was conducted as part of the National Animal Health Monitoring System's Dairy 2014 study, which included dairy operations in 17 states. Size categories were assigned as follows: small (30–99 cows), medium (100–499 cows), and large (≥500 cows). Trained assessors visited 191 dairy operations from March through July 2014 and recorded locomotion and hock scores (on a 3-point scale), and the number of thin cows (body condition score ≤2.25) from a total of 22,622 cows (average 118 cows per farm). The majority of cows (90.4%) were considered to be sound (locomotion score = 1), 6.9% were mild/moderately lame (locomotion score = 2), and 2.7% were severely lame (locomotion score = 3). Similarly, most cows (87.3%) had no hock lesions (hock score = 1), 10.1% had mild lesions (hock score = 2), and 2.6% had severe hock lesions (hock score = 3). A low percentage of cows (4.2%) were thin. Univariate comparisons were performed using PROC LOGLINK, which accounts for study design and weighting. Variables meeting the univariate screening criterion of P < 0.20 were eligible for entry into multivariable models. Statistical significance in the multivariable models was declared at P < 0.05. Large operations had a lower within-herd prevalence of cows with locomotion score ≥2 and locomotion score = 3 compared with small or medium-sized operations. Operations on which cows were kept primarily on pasture had a lower percentage of locomotion score = 3 than those housed in freestall or open/dry lot operations. The use of sand bedding was associated with a lower within-herd prevalence of locomotion score ≥2 than straw/hay or dry/composted manure as the primary bedding material. Sand bedding was also associated with a lower within-herd prevalence of locomotion score = 3 than other bedding types except for rubber mats or mattresses. Operations that housed cows in an open/dry lot had a lower percentage of hock score ≥2 and hock score = 3 than other housing types. Providing sprinklers for heat abatement and having a nutritionist balance rations for cows was associated with a lower percentage of thin cows. Results from this study highlight management practices that may reduce the prevalence of lameness, hock lesions, and thin cows on dairy operations in the United States.     

The contribution of previous lameness events and body condition score to the occurrence of lameness in dairy herds: A study of 2 herds

It has been demonstrated that low body condition and previous occurrence of lameness increase the risk of future lameness in dairy cows. To date the population attributable fraction (PAF), which provides an estimate of the contribution that a risk factor makes toward the total number of disease events in a population, has not been explored for lameness using longitudinal data with repeated measures. Estimation of PAF helps to identify control measures that could lead to the largest improvements on-farm. The aim of this study was to use longitudinal data to evaluate the proportion of lameness that could be avoided in 2 separate herds (2 populations) through (1) reduced recurrence of previous lameness events, (2) and moving body condition score (BCS) into more optimal ranges. Data were obtained from 2 UK dairy herds: herd A, a 200-cow herd with 8 yr of data from a total of 724 cows where lameness events were based on weekly locomotion scores (LS; 1 to 5 scale), and herd B, a 600-cow herd with data recorded over 44 mo from a total of 1,040 cows where treatment of clinical cases was used to identify lameness events. The PAF for categories of BCS were estimated using a closed equation appropriate for multiple exposure categories. Simulation models were used to explore theoretical scenarios to reflect changes in BCS and recurrence of previous lameness events in each herd. For herd A, 21.5% of the total risk periods (cow-weeks) contained a lameness event (LS 3, 4, or 5), 96% of which were repeat events and 19% were recorded with BCS <2 (3 wk previously; 0 to 5 scale). When lameness events were based on 2 consecutive weeks of LS 4 or 5, 4% of risk periods were recorded as lame, of which 89.5% were repeat events. For herd B, 16.3% of the total risk periods (consecutive 30 d) contained a lameness event (72.6% were repeat events) and 20% were recorded with BCS ≤2 (0 to 120 d previously). The median PAF for all previous lameness was between 79 and 83% in the 2 herds. Between 9 and 21% of lameness events could be attributed to previous lameness occurring >16 wk before a risk period. The median PAF estimated for changes in BCS were in the region of 4 to 11%, depending on severity of lameness. Repeated bouts of lameness made a very large contribution to the total number of lameness events. This could either be because certain cows are initially susceptible and remain susceptible, due to the increased risk associated with previous lameness events, or due to interactions with environmental factors. This area requires further research.     

Effects of vitamin E supplementation on and the association of body condition score with changes in peroxidative biomarkers and antioxidants around calving in dairy heifers

The objective of this study was to investigate the effect of vitamin E supplementation on oxidative status in blood, liver, milk, and ovarian follicular fluid in periparturient heifers. Vitamin E supplementation started 8 wk before calving and continued until 8 wk postpartum. Grass silage was the main forage fed during the experiment. In addition, supplemented heifers (n = 9) received 3,000 IU of vitamin E daily on a carrier food; control heifers (n = 9) consumed only the carrier food. Blood samples and liver biopsies were taken frequently throughout the study and ovarian follicular fluid was sampled at 8 wk postpartum. Body condition score was scored weekly and milk yield was measured daily. A marker of oxidative damage, determinable reactive oxygen metabolites (d-ROM), and a set of antioxidants were measured in blood, liver, milk, and ovarian follicular fluid. Control heifers had a low vitamin E status, and selenium status was marginal in control and supplemented heifers. Vitamin E supplementation increased vitamin E concentrations in blood, liver, and ovarian follicular fluid and increased triacylglycerol in liver. Serum d-ROM were not reduced by vitamin E supplementation. Superoxide dismutase and glutathione peroxidase activity in red blood cells and liver and glutathione peroxidase activity in ovarian follicular fluid were not affected by vitamin E supplementation and they were not increased around calving. Protein thiol groups and ratio of reduced glutathione to oxidized glutathione were also not increased around calving. These results suggest that heifers around calving experience a low level of oxidative processes. This might be caused by lower than expected milk production attributed to a low forage intake. Serum d-ROM were negatively correlated with protein thiol groups and positively correlated with the activity of glutathione peroxidase in red blood cells, oxidized glutathione, and the ratio of reduced glutathione and oxidized glutathione in serum. The lack of treatment effects allowed estimation of the effects of body condition 4 wk before calving and the loss of body condition on markers of lipid peroxidation and antioxidants. A trend that a body condition of ≥3 might result in more oxidative damage measured by serum d-ROM was observed, but fatter heifers had a significantly higher ratio of reduced glutathione to oxidized glutathione.     

Genetic parameters for level and change of body condition score and body weight in dairy cows

(Co)variance components for body condition score (BCS), body weight (BW), BCS change, BW change, and milk yield traits were estimated. The data analyzed included 6646 multiparous Holstein-Friesian cows with records for BCS, BW, and(or) milk yield at different stages of lactation from 74 dairy herds throughout Southern Ireland. Heritability estimates for BCS ranged from 0.27 to 0.37, while those for BCS change ranged from 0.02 to 0.10. Heritability estimates for BW records varied from 0.39 to 0.50, while heritabilities for BW change were similar to those observed for BCS change (0.03 to 0.09). The genetic correlations between BCS and BW at the same days in milk deviated little from 0.50, and the genetic correlations between BCS change and BW change over the same period ranged from 0.42 to 0.55. BCS and BW directly postpartum were both phenotypically and genetically negatively correlated with both BW change and BCS change in early lactation. The genetic correlations between BCS and milk yield were negative. The results of the present study show that animals that lose most BCS in early lactation tend to gain most BCS in late lactation, a trend also exhibited by BW.     

Associations between body condition score,locomotion score,and sensor-based time budgets of dairy cattle during the dry period and early lactation

Lameness, one of the most important disorders in the dairy industry, is related to postpartum diseases and has an effect on dairy cow welfare, leading to changes in cows' daily behavioral variables. This study quantified the effect of lameness on the daily time budget of dairy cows in the transition period. In total, 784 multiparous dairy cows from 8 commercial Dutch dairy farms were visually scored on their locomotion (score of 1–5) and body condition (score of 1–5). Each cow was scored in the early and late dry period as well as in wk 4 and 8 postpartum. Cows with locomotion scores 1 and 2 were grouped together as nonlame, cows with score 3 were considered moderately lame, and cows with scores 4 and 5 were grouped together as severely lame. Cows were equipped with 2 types of sensors that measured behavioral parameters. The leg sensor provided number of steps, number of stand-ups (moving from lying to standing), lying time, number of lying bouts, and lying bout length. The neck sensor provided eating time, number of eating bouts, eating bout length, rumination time, number of rumination bouts, and rumination bout length. Sensor data for each behavioral parameter were averaged between 2 d before and 2 d after locomotion scoring. The percentage of nonlame cows decreased from 63% in the early dry period to 46% at 8 wk in lactation; this decrease was more severe for cows with higher parity. Cows that calved in autumn had the highest odds for lameness. Body condition score loss of >0.75 point in early lactation was associated with lameness in wk 4 postpartum. Moderately lame cows had a reduction of daily eating time of around 20 min, whereas severely lame cows had a reduction of almost 40 min. Similarly, moderately and severely lame dry cows showed a reduction of 200 steps/d, and severely lame cows in lactation showed a reduction of 600 steps/d. Daily lying time increased by 26 min and lying bout length increased by 8 min in severely lame cows compared with nonlame cows. These results indicate a high prevalence of lameness on Dutch dairy farms, with an increase in higher locomotion scores from the dry period into early lactation. Time budgets for multiparous dairy cows differed between the dry period and the lactating period, with a higher locomotion score (increased lameness) having an effect on cows' complete behavioral profile. Body condition score loss in early lactation was associated with poor locomotion postpartum, whereas lameness resulted in less eating time in the dry period and early lactation, creating a harmful cycle.     

Cow body shape and automation of condition scoring

The feasibility of including a body shape measure in methods for automatic monitoring of body reserves of cattle was evaluated. The hypothesis tested was that the body shape of a fatter cow is rounder than that of a thin cow and, therefore, may better fit a parabolic shape. An image-processing model was designed that calculates a parameter to assess body shape. The model was implemented, and its outputs were validated against ultrasonic and thermal camera measurements of the thickness of fat and muscle layers, and manual body condition scoring of 186 Holstein-Friesian cows. The thermal camera overcomes some of the drawbacks of a regular camera; the hooks and the tailhead nadirs of a thin cow diverged from the parabolic shape. The correlation between thermal camera's measurements and fat and muscle thickness was 0.47. Mean body condition scorings were 2.18, 2.15, and 2.23, with no significant difference found across the assessment methods. Further research is needed to achieve fully automatic, accurate body condition scoring.     

Comparison of feeding management and body condition of dairy cows in herds with low and high mastitis rates

Feeding practices, ration composition, and body condition scores (BCS) were assessed in an observational case-contrast study of Norwegian dairy herds with low (n = 98) and high (n = 94) mastitis infection rates. Differences between the 2 groups of herds were associated with feeding practices and amount of roughage. More herds in the low-infection group were fed a reduced amount of roughage at drying off, and reduced rations during the dry period resulted in lower BCS at calving. Cows in the low-infection herds had significantly lower BCS in the last month before calving and the first month of lactation than cows in the high-infection herds. The significant associations between mastitis infection rates and BCS, frequency of concentrate feeding, and amount of roughage at drying off and during the dry period indicated that feeding practices may have an important influence on the risk of mastitis in Norwegian dairy cows.     

Short communication: An observational study investigating inter-observer agreement for variation over time of body condition score in dairy cows

Body condition score (BCS) is strongly correlated with energy reserves. The ease, rapidity of scoring, and high intra- and inter-observer repeatability make it a widely used herd management tool in bovine practice and in scientific studies. Loss or gain of BCS, rather than a single BCS measurement, is frequently used to monitor energy balance in dairy cows. It is unknown if the difference between 2 BCS measures taken at different moments (ΔBCS) would demonstrate inter-observer agreement similar to that of a single BCS measurement. The objective of this study was to compare inter-observer agreement of BCS and ΔBCS in dairy cows when multiple observers perform data collection. An observational study was conducted between April and September 2015; 3 observers independently assessed BCS of 73 Holstein cows from 1 commercial dairy herd. Body condition score assessments of the animals were performed between 1 and 20 d in milk (early lactation; exam 1) and again between 41 and 60 d in milk (peak of milk production; exam 2). Quadratic weighted kappa (κ_w) was computed to quantify agreement between observers for single BCS measurements and ΔBCS. For single BCS measurements, κ_w of 0.79 (95% CI: 0.69, 0.85) and 0.84 (95% CI: 0.77, 0.89) were obtained for exam 1 and exam 2, respectively. Such values would be interpreted as strong agreement and are consistent with the available literature on BCS repeatability. When computing agreement for ΔBCS, a κ_w value of 0.49 (95% CI: 0.32, 0.63) was obtained, suggesting moderate agreement between observers. These findings suggest that studies investigating single BCS measures could use many observers with a high degree of accuracy in the results. When ΔBCS is the parameter of interest, more reliable results would be obtained if one observer conducts all assessments.     

The effect of body condition score at calving and supplementation with Saccharomyces cerevisiae on milk production, metabolic status, and rumen fermentation of dairy cows in early lactation

The objective of this study was to examine the effects of live yeast (LY) supplementation and body condition score (BCS, 1-5 scale) at calving on milk production, metabolic status, and rumen physiology of postpartum (PP) dairy cows. Forty Holstein-Friesian dairy cows were randomly allocated to a 2 × 2 factorial design and blocked by yield, parity, BCS, and predicted calving date. Treatments were body condition at calving (low for BCS ≤3.5 or high for BCS ≥3.75; n = 20) and supplementation with LY (2.5 and 10 g of LY/d per cow for pre- and postcalving, respectively; control, no LY supplementation; n = 20). The supplement contained 10⁹ cfu of Saccharomyces cerevisiae/g (Yea-Sacc¹⁰²⁶ TS, Alltech Inc., Nashville, TN). Daily milk yield, dry matter intake, milk composition, BCS, body weight, and backfat thickness were recorded. Blood samples were harvested for metabolite analysis on d 1, 5, 15, 25, and 35 PP. Liver samples were harvested by biopsy for triacylglycerol (TAG) and glycogen analysis on d 7 precalving, and on d 7 and 21 PP. Rumen fluid was sampled by rumenocentesis for all cows on d 7 and 21 PP. Supplementation with LY had no effect on milk yield, dry matter intake, rumen fluid pH, or blood metabolites concentration of dairy cows with high or low BCS at calving. Feeding LY increased rumen acetate proportion and protozoal population, tended to increase liver glycogen, and decreased rumen ammonia nitrogen during early lactation. Over-conditioned cows at calving had greater body reserve mobilization and milk production and lower feed intake, whereas cows with a moderate BCS at calving had greater feed intake, lower concentrations of nonesterified fatty acids and β-hydroxybutyrate, lower liver TAG and TAG:glycogen ratio, and faster recovery from body condition loss. Additionally, the data suggest that concentrations of liver enzymes in blood might be used as an indicator for liver TAG:glycogen ratio. Results indicate that in the case of this experiment, where the control treatment was associated with an acceptable rumen pH, feeding yeast did not significantly improve indicators of energy status in dairy cows.     

Associations among body condition score, body weight, somatic cell count, and clinical mastitis in seasonally calving dairy cattle

The objective of this study was to determine if an association existed among body condition score (BCS), body weight (BW), and udder health, as indicated by somatic cell score (SCS) and cases of clinical mastitis (CM). The data consisted of 2,635 lactations from Holstein-Friesian (n = 523) and Jersey (n = 374) cows in a seasonal calving pasture-based research herd between the years 1986 and 2000, inclusive. Increased BCS at calving was associated with reduced SCS in first- and second-parity cows, and greater SCS in cows of third parity or greater. This relationship persisted for most BCS traits throughout lactation. Body weight was positively associated with SCS, although the effect was greater in Jersey cows than in Holstein-Friesians. Increased BCS and BW loss in early lactation were associated with lower SCS and a reduced probability of a high test-day SCC. Body condition score was not significantly related to CM with the exception of a curvilinear relationship between the daily rate of BCS change to nadir and CM in early lactation. Several BW variables were positively associated with a greater likelihood of CM. Nevertheless, most associations with udder health lacked biological significance within the ranges of BCS and BW generally observed on-farm. Results are important in assuring the public that modern dairy systems, where cows are subjected to substantial amounts of BCS mobilization in early lactation, do not unduly compromise cow udder health.     

Comparison of models to identify lame cows based on gait and lesion scores, and limb movement variables

Bovine lameness results in pain and suffering in cattle and economic loss for producers. A system for automatically detecting lame cows was developed recently that measures vertical force components attributable to individual limbs. These measurements can be used to calculate a number of limb movement variables. The objective of this investigation was to explore whether gait scores, lesion scores, or combined gait and lesion scores were more effectively captured by a set of 5 limb movement variables. A set of 700 hind limb examinations was used to create gait-based, lesion-based, and combined (gait- and lesion-based) models. Logistic regression models were constructed using 1, 2, or 3 d of measurements. Resulting models were tested on cows not used in modeling. The accuracy of lesion-score models was superior to that of gait-score models; lesion-based models generated greater values of areas under the receiving operating characteristic curves (range 0.75 to 0.84) and lower mean-squared errors (0.13 to 0.16) compared with corresponding values for the gait-based models (0.63 to 0.73 and 0.26 to 0.31 for receiving operating characteristic and mean-squared errors, respectively). These results indicate that further model development and investigation could generate automated and objective methods of lameness detection in dairy cattle.     

Lame cows on Australian dairy farms: A comparison of farmer-identified lameness and formal lameness scoring,and the position of lame cows within the milking order

On Australian pasture-based farms, where cows may often walk several kilometers and stand for several hours per day in a crowded concrete yard while they wait to be milked, the potential for lameness to negatively affect animal welfare is of ongoing concern. Several studies have shown that farmers tend to underestimate the incidence of lameness. Further, improving farmer diagnosis/identification of lameness is likely to result in more prompt treatment, which in turn will improve clinical and animal welfare outcomes. We scored 19,154 cows over 50 farms for lameness, in herd groups ranging from approximately 100 to 1,000 cows, as they left the milking parlor. We compared these results with farmer-diagnosed lameness records on the same day. We used a scoring system of 0, walks normally; 1, walks unevenly; 2, lame; and 3, very lame. All very lame cows had been detected by the farmer, but overall, farmers detected only 24% of cows identified by lameness scoring. An analysis of the position of lame cows within the milking order showed that lameness scoring of the entire herd was necessary to detect all the lame cows as only 60% of lame cows appeared in the last 30% of cows to be milked. However, lameness scoring only the last 200 cows to be milked could be used as a screening test to identify herds with a lameness prevalence below a given threshold.