Detection of quantitative trait loci affecting lameness and leg conformation traits in Danish Holstein cattle

Lameness is an important factor for culling animals. Strong legs and feet improve herd life of dairy cows. Therefore, many countries include leg and feet conformation traits in their breeding programs, often as early predictors of longevity. However, few countries directly measure lameness related traits to include these in a breeding program. Lameness indices in 3 different lactations and 5 leg conformation traits (rear legs side view, rear legs rear view, hock quality, bone quality, and foot angle) were measured on granddaughters of 19 Danish Holstein grandsires with 33 to 105 sons. A genome scan was performed to detect quantitative trait loci (QTL) based on the 29 autosomes using microsatellite markers. Data were analyzed across and within families for QTL affecting lameness and leg conformation traits. A regression method and a variance component method were used for QTL detection. Two QTL each for lameness in the first [Bos taurus autosome (BTA); BTA5, BTA26] and second (BTA19, BTA22) lactations were detected. For the 5 different leg conformation traits, 7 chromosome-wise significant QTL were detected across families for rear legs side view, 5 for rear legs rear view, 4 for hock quality, 4 for bone quality, and 1 for foot angle. For those chromosomes where a QTL associated with 2 different traits was detected (BTA1, BTA11, BTA15, BTA26, and BTA27), a multitrait-1-QTL model and a multitrait-2-QTL model were performed to characterize these QTL as single QTL with pleiotropic effects or distinct QTL.     

Seasonal incidence of lameness and risk factors associated with thin soles, white line disease, ulcers, and sole punctures in dairy cattle

Lameness is a multifactorial condition with many causes. In this study, cow lifetime records were used to quantify the incidence of specific lameness-causing lesions and investigate factors associated with those lesions. Of primary interest were the effects of seasonality and the effects of thin soles (TS). Thin sole-induced toe ulcers (TSTU) occurring adjacent to the white line in the apical portion of the weight-bearing surface were distinguished from white line disease (WLD) occurring in the region of the abaxial heel sole junction. Sole (SU), heel (HU), and toe (TU) ulcers; TS; sole punctures (SP); leg injuries (INJ); and other (OTH) lesions (e.g., infectious diseases, laminitis, unclassified hemorrhage) were also considered. Data were collected from May 2004 through October 2007 and included records for 4,915 cows of which 1,861 had at least one recorded lameness event. Of these, 20% were TSTU, 20% OTH, 16% SU, 13% TS, 10% WLD, 8% HU, 6% INJ, 4% SP, and 2% TU. Annual incidence risk for lameness was 49.1%. Overall incidence rate for lameness was 1.41/1,000 cow-days, and rates for all lesions were highest in the summer. As parity increased, so did incidence rates for TS, SU, WLD, HU, and INJ. For TS, TSTU, and WLD, incidence rates were lowest in early lactation (16 to 60 DIM), whereas for SU, HU, TU, incidence rates were highest in mid lactation (61 to 150 DIM). Cox proportional hazard models for TS, TSTU, WLD, SU, HU, TU, and SP included age and year of first calving and milk production capacity. Prior/concurrent lameness events, season, parity, and stage of lactation were included as time-dependent effects. Prior/concurrent TS increased the hazard for all other lesions, particularly TSTU, and HU. Having any other prior claw lesion also increased the hazard for all lesions. Hazard was highest in summer for all lesions except TU. Stage of lactation was a significant effect in hazard of TSTU, which was lowest in mid lactation (61 to 150 DIM).     

Effects of routine treatment with nonsteroidal anti-inflammatory drugs at calving and when lame on the future probability of lameness and culling in dairy cows: A randomized controlled trial

Claw horn lesions (CHL) are reported as the most common cause of lameness in intensive dairy systems. Despite their prevalence, the underlying pathological mechanisms and preventive strategies for CHL remain poorly understood. Recent advances have pointed to the role of inflammation in disease aetiopathogenesis. Moderating inflammation from first calving may lead to long-term benefits and a viable intervention for treating and preventing disease. We conducted a 34-mo randomized controlled trial to investigate the effects of routine treatment with the nonsteroidal anti-inflammatory drug ketoprofen at calving and during treatment for lameness, on the future probability of lameness and culling, caused by exposure to normal farm conditions. A cohort of dairy heifers were recruited from a single, commercial dairy herd between January 8, 2018, and June 22, 2020, and randomly allocated to one of 4 treatment groups before first calving. The lactating herd was lameness scored every 2 wk on a 0 to 3 scale, to identify animals that became lame (single score ≥2a) and hence required treatment. Animals in group 1 received a therapeutic trim and a hoof block on the sound claw (if deemed necessary) every time they were treated for lameness. Animals in group 2 received the same treatment as group 1 with the addition of a 3-d course of ketoprofen (single dose daily) every time they were treated for lameness. Animals in group 3 received the same treatment as group 2 with the addition of a 3-d course of ketoprofen (single dose daily) starting 24 to 36 h after each calving. Animals in group 4 received a 3-d course of ketoprofen (single dose daily) every time they were identified with lameness. No therapeutic trim was administered to this group, unless they were identified as severely lame (a single score ≥3a). Animals were followed for the duration of the study (ending October 23, 2020). Probability of lameness was assessed by a lameness outcome score collected every 14 d. Data on culling was extracted from farm records. One hundred thirty-two animals were recruited to each group, with data from 438 animals included in the final analysis (111 in group 1, 117 in group 2, 100 in group 3, and 110 in group 4). Mixed effect logistic regression models were used to evaluate the effect of treatment group on the ongoing probability of lameness. Compared with the control group (group 1), animals in group 3 were less likely to become lame (odds ratio: 0.66) and severely lame (odds ratio: 0.28). A Cox proportional hazards survival model was used to investigate the effect of treatment group on time to culling. Compared with group 1, animals in groups 2 and 3 were at reduced risk of culling (hazard ratios: 0.55 and 0.56, respectively). The lameness effect size we identified was large and indicated that treating a cohort of animals with the group 3 protocol, would lead to an absolute reduction in population lameness prevalence of approximately 10% and severe lameness prevalence of 3%, compared with animals treated in accordance with conventional best practice (group 1).     

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.     

Gait pattern of heifers before and after claw trimming: a high-speed cinematographic study on a treadmill

The manner in which the claws contacted the ground at the walk was evaluated in 18 healthy heifers. The animals were filmed before and after claw trimming while walking on a treadmill using high-speed cinematography (500 frames/s). For each limb, 4 consecutive steps were recorded from a side and a frontal plane. The objectives of the study were to evaluate 1) the order of claw contact with the treadmill surface, 2) the initial claw contact area, and 3) the effect of trimming on claw contact patterns. The heifers placed their front feet on the ground in a plane sagittal to the shoulders, whereas the hind feet were advanced more toward the median plane. Before trimming, the lateral claws contacted the ground before the medial in 83% of front and 100% of hind limbs. Trimming changed the percentage to 92% in the front and to 97% in the hind limbs. The percentage with which the heel of the lateral claws became the region of initial contact with the ground increased from 47 to 64% in the front feet and from 50 to 78% in the hind feet. In the medial claws of the forelimbs, claw trimming shifted the region of initial contact from the toe to the abaxial wall and heel. In the hind limbs, the main region of initial contact of the medial claws became the abaxial wall. Weight bearing by the medial claw became visibly apparent only during the midstance, propulsion, and push-off phases. “Heel first” contact of the lateral claws in the front and hind limbs may be the normal gait pattern in cattle. On hard surfaces, this pattern may lead to overload and predispose to disease, especially in the hind limbs.     

Effects of prolonged nutrient restriction on baseline and periprandial plasma ghrelin concentrations of postpubertal Holstein heifers

Objectives of this study were to measure both daily and periprandial plasma ghrelin concentrations of postpubertal Holstein heifers during prolonged undernutrition. Following an acclimation period, Holstein heifers [n = 10; 339.5 ± 8.6 kg of body weight (BW)] were fed ad libitum [well fed (WF); n = 5] or restricted to 50% of ad libitum intake [underfed (UF); n = 5) for 8 wk. Body condition scores (BCS) were recorded at the beginning and end of the treatment period, and weekly measurements of BW, plasma ghrelin, progesterone, and nonesterified fatty acids (NEFA) concentrations were obtained. Ovarian follicular and luteal structures were measured twice weekly via transrectal ultrasonography. Plasma ghrelin concentrations were also measured during a periprandial window bleed conducted at the end of the experiment. During the window bleed, samples were collected every 15 min between 0500 and 0900 h, with feed offered at 0700 h. Underfed heifers lost BW and BCS, whereas WF heifers gained weight and either increased or maintained BCS. Chronic underfeeding increased circulating ghrelin and NEFA concentrations. By wk 4 of the treatment period, circulating ghrelin concentrations of the UF heifers reached a plateau. Periprandial fluctuations in ghrelin concentrations were apparent as plasma ghrelin concentrations changed over time. Overall differences in periprandial plasma ghrelin concentrations were primarily due to prefeeding effects of plane of nutrition. Plasma ghrelin concentrations and change in BCS were negatively correlated such that heifers that lost the most BCS had the highest concentrations of circulating ghrelin. Two of the 5 UF heifers became anestrus by wk 3 of the treatment period. Despite being of similar age, the heifers that became anestrus had lower BW and plasma ghrelin concentrations than the UF heifers that continued to ovulate. In the current experiment, long-term undernutrition elicited ghrelin responses similar to those reported for shorter durations of nutrient restriction in cattle and other ruminants. These results demonstrate that plane of nutrition is a chronic regulator of plasma ghrelin concentrations, and that these concentrations can be experimentally manipulated in postpubertal heifers for up to 8 wk with no evidence of an adaptive response.     

Nutrient utilization of differing forage-to-concentrate ratios by growing Holstein heifers

Traditionally, high-forage, low-concentrate diets fed ad libitum have been the primary system of feeding dairy heifers. However, high-concentrate diets can be fed at restricted intakes to reach desired rates of gain and increase nutrient efficiency. A total mixed ration containing high corn silage (CS; HCS: 77% CS, 23% concentrate) or low CS (LCS: 67% concentrate, 33% CS) was fed at restricted intakes in 2 trials to evaluate nutrient utilization by growing heifers. In the first trial, 4 ruminally cannulated heifers (298 ± 16 kg of body weight) were fed to study differences in rumen pH, volatile fatty acid and ammonia concentrations, and mass of rumen contents. In situ determinations were made on the total mixed ration and CS. Low CS rations were digested more rapidly in situ when compared with HCS (4.5 vs. 2.3 ± 0.3%/h), and no differences were observed in CS digestibility when incubated in the rumen of heifers fed either ration. Mean rumen pH tended to be lower for LCS than for HCS (5.9 vs. 6.2 ± 0.1). Individual and total rumen volatile fatty acid concentrations and rumen ammonia concentration were not different between treatments. Total mass of rumen contents was lower for LCS. In the second trial, four 6-mo-old heifers (172 ± 14 kg of body weight) and four 12-mo-old heifers (337 ± 10 kg of body weight) were used. Digestibility of dry matter was greater for the LCS than the HCS diet in both age groups (76.3 vs. 71.1% for 12-mo-old heifers; 71.4 vs. 68.9% for 6-mo-old heifers). Apparent digestibility of N was not different between treatments; however, retained N was higher for the LCS diets for both age groups. Fecal output was significantly reduced in the LCS diets for both age groups. Feeding low-forage, high-concentrate diets to growing dairy heifers at restricted intakes, although more highly digestible, resulted in few significant differences in rumen fermentation patterns and lower fecal output.     

Presynchronization with gonadotropin-releasing hormone does not improve fertility in Holstein heifers

Holstein dairy heifers were randomly assigned to 1 of 2 treatments to determine whether a presynchronization strategy using GnRH would improve reproductive performance after synchronization of ovulation and timed artificial insemination (TAI). Heifers (n = 82) in the first treatment (GPG) received a hormonal protocol for synchronization of ovulation and TAI (100 μg of GnRH, d 0; 25 mg of PGF_2α, d 6; 100 μg of GnRH + TAI, d 8); whereas heifers (n = 84) in the second treatment (GGPG) received GPG, but with the addition of a GnRH injection (100 μg) 7 d before initiation of the GPG protocol. The proportion of heifers receiving AI before d 8 was similar for GPG (4.9%) and GGPG (9.5%), and the proportion of heifers diagnosed pregnant 30 d after AI did not differ between treatments (45 vs. 51%, respectively). Treatment did not affect the proportion of heifers ovulating after the second GnRH injection or the proportion in which a corpus luteum regressed after treatment with PGF_2α. In conclusion, presynchronization with GnRH 7 d before initiation of synchronization of ovulation using GnRH and PGF_2α did not affect the proportion of heifers expressing estrus before TAI or improve synchronization response or fertility to the synchronization protocol.     

Changes in the soft-tissue thickness of the claw sole in Holstein heifers around calving

Claw horn disruption lesions are a common cause of lameness in dairy cattle. It is commonly agreed that they develop due to excessive pressure from the distal phalanx on the horn-producing tissue in the sole. The distal phalanx is supported by the suspensory apparatus, a large proportion of which is made up of connective tissue. It has been hypothesized that increased laxity of the connective tissue due to hormonal changes around calving may lead to decreased support of the distal phalanx, resulting in a sinking of the bone and increased pressure on the horn-producing tissue. In this longitudinal study, our first objective was to determine whether the thickness of the soft tissue related to the claw sole (the combined depth of the digital cushion and corium; soft-tissue thickness, STT) in the weight-bearing hind claws of live heifers changed around calving (the period from approximately 3 wk before calving to 2 wk after calving). Our second objective was to evaluate the relationship between the body condition score (BCS) of recruited heifers and the STT estimates we obtained. We measured STT (defined as the distance between the distal phalanx and the sole horn) in the apex and the posterior part of the sole of the hind claws of 34 Holstein heifers 4 times over 3 to 4 wk around calving. We determined STT by ultrasonographic measurements through the sole horn on weight-bearing claws. The overall mean STT at site 1 was 3.3 mm [minimum–maximum (min–max): 1.8 to 5.2 mm], and the mean at site 2 was 3.7 mm (min–max: 2.2 to 5.8). The overall mean STT was thickest in the first examination before calving [site 1: 3.4 mm (min–max: 1.9 to 4.7); site 2: 4.1 mm (min–max: 2.7 to 5.8)] and thinnest at site 1 in the second examination after calving (3.2 mm, min–max: 1.8 to 5.2) and at site 2 at the first examination after calving (3.5 mm, min–max: 2.2 to 5.0). We observed an average reduction in STT of ?0.2 mm (min–max: 0.8 to ?0.9 mm) at site 1 during the study period, but we did not observe this reduction in all animals. At site 2, we found an average reduction in STT of ?0.6 mm (min–max: 0.8 to ?1.3 mm) from 10 d before calving to 5 d after calving, corresponding to a decrease of approximately 15% (min–max: 0 to 31%). We suggest that this reduction was caused by a rotation of the distal phalanx toward the posterior part of the sole horn in the weeks around calving. During the same period, heifer BCS decreased between 0.25 and 0.5 increments in the BCS scale, but we found no correlation between BCS and STT. However, the heifers experienced many changes related to management, feeding, and time budget during the study period, and the rotation of the distal phalanx and reduction of the STT might be explained not only by calving but also by other factors that affect heifers and their claws during the transition period.     

Short communication: Use of lameness scoring to genetically improve claw health in Austrian Fleckvieh,Brown Swiss,and Holstein cattle

The specific objective of this study was to evaluate the use of lameness scoring to genetically improve claw health in Austrian Fleckvieh, Brown Swiss, and Holstein cows based on data from the “Efficient Cow” project. In 2014, a 1-yr data collection was carried out. Data from 6,519 cows kept on 161 farms were recorded. At each time of milk recording, lameness scores were assessed by trained staff of the milk recording organizations. Hoof trimming on these farms was documented and recorded as well. Veterinarian diagnoses and culling due to foot and leg problems from these farms were available from the routine recording system. As repeated lameness records per cow and lactation were available, an overall lactation lameness score was calculated. Estimated heritabilities for lameness were 0.11, 0.05, and 0.09 for Fleckvieh, Brown Swiss, and Holstein, respectively; however, only heritability estimates for Fleckvieh were significantly different from zero. Breeding values for lameness were obtained, reversed in sign, and cows were ranked according to their breeding value. A low breeding value for lameness resistance (the bottom 10% of the cows) was associated with a significantly higher frequency of trimmed cows, which indicates that the cows selected by the farmer to be trimmed are not completely random. Additionally, a high breeding value for lameness resistance (the top 10% of the cows) was associated with lower frequencies of claw diseases recorded at trimming, claw and leg diagnoses, and culling due to foot and leg problems, which highlights the usefulness of lameness scoring for genetic improvement of claw health. Overall, selecting for a better lameness score has the potential to reduce claw diseases, especially the frequency of severe claw diseases that lead to culling.     

A multistate modeling approach to investigate long-term effects of claw horn disruption lesions and early lesion development in dairy cows

Claw horn disruption lesions (CHDL) are a leading cause of lameness in dairy cattle, and the development, effect, and pathology of these lesions remains an open area of interest within dairy cattle health. Current literature typically attempts to measure the effect of risk factors on the development of CHDL over a relatively short time period. Further understanding of the interaction of CHDL and the long-term effect of early CHDL in a cow's life remains an important area of research which is so far mostly unexplored. In this study 57,974 cows from 1,332 herds were selected and their regular claw trimming records containing important claw health information were used to model the long-term effect of lesions in a cow's lifetime in a 6-state multistate model. A multistate model predicts the time before transition from any one state to another and the probability of transition to a future state. The 6 lesion states that were modeled were as follows: never had a lesion, first recorded lesion event, no recorded lesion after first lesion event, second or subsequent recorded lesion event, no recorded lesion after second or subsequent lesion event, and culled. The effect of various cow level covariates on the transition probabilities between various states was tested. For the first time, this study shows the importance and effect of the first lesion and other cow level factors on long-term claw health. Model results showed that the timing and severity of the first recorded lesion event significantly influenced the likelihood of a future lesion being present. Cows with CHDL present within the 180 d of first calving had a short-term increased risk and long-term decreased risk of a future lesion, compared with cows that present with CHDL later than 180 d of first lactation. Moreover, presence of a severe first lesion increased a cow's risk of a future lesion being present. The model was used to evaluate the relative difference between high-risk cows (age of first calving ≥793 d, breeding values in the lowest quartile) and low-risk cows (age of first calving ≤718 d, breeding values in the highest quartile). Our results indicated that these low-risk cows present with a lesion on an average 3 mo later than high-risk cows. Furthermore, results from the model evaluation of a simulated herd with cows with breeding values in the higher quartile indicated that cows present with a CHDL on an average 7.5 mo later compared with a herd where cows have breeding values distributed in a lower quartile.     

Measures of weight distribution of dairy cows to detect lameness and the presence of hoof lesions

There is increasing interest in automated methods of detecting lame cows. Hoof lesion data and measures of weight distribution from 61 lactating cows were examined in this study. Lame cows were identified with different numerical rating scores (NRS) used as thresholds (NRS >3 and NRS ≥3.5) for lameness. The ratio of weight applied to a pair of legs (LWR) when the cow was standing was calculated using a special weigh scale, and the cows were gait scored using a 1 to 5 NRS. Hoof lesions were scored and the cows placed into 1 of 4 mutually exclusive categories of hoof lesion: a) no lesions, b) moderate or severe hemorrhages, c) digital dermatitis, and d) sole ulcers. Regression analysis and receiver operating characteristic (ROC) curves were used to analyze the relation between hoof lesions and LWR. A clear relationship was found between NRS and LWR for the cows with sole ulcers (R² = 0.79). The LWR could differentiate cows with sole ulcers from sound cows with no hoof lesions [area under the curve (AUC) = 0.87] and lame cows from nonlame cows with lameness thresholds NRS >3 (AUC = 0.71) and NRS ≥3.5 (AUC = 0.88). There was no relationship between LWR and NRS for cows with digital dermatitis. Measurement of how cows distribute their weight when standing holds promise as a method of automated detection of lameness.     

Technical note: Assessing lameness in tie-stalls using live stall lameness scoring

Video stall lameness scoring (SLS) has been shown to be comparable to video locomotion scoring for evaluating lameness in dairy cows housed in tie-stalls and may be a more practical and easier method to measure lameness in a herd. We compared live SLS to video SLS and to live locomotion scoring. A total of 685 lactating cows subsampled from 27 commercial dairy herds were examined for lameness through live and video SLS. Cows scored with the live or video SLS system were scored for 4 behavioral indicators while still in their stall: weight shifting (shift), standing on the edge of the stall (edge), uneven weight bearing while standing (rest), and uneven weight bearing while moving from side to side (uneven). Two observers live scored and video scored for SLS. Lameness prevalence from video SLS and live SLS were similar (31 vs. 30%, respectively). Prevalence of the behavioral indicators varied from 0.59 to 58.2%. Sensitivity and specificity of live SLS was calculated using video SLS as the gold standard for lameness detection in tie-stalls. Sensitivity of live SLS was 0.83 and specificity was 0.94. False positives and false negatives for lameness were 14.4 and 16.8%, respectively. When comparing the prevalence of lameness measured through video or live SLS at the herd level, live SLS for lameness was correlated to video SLS (r = 0.91) with a Cohen's kappa coefficient of 0.79 (95% confidence limit = 0.73–0.84). Average exact agreement in the behavior indicators observed ranged from 80 to 100%. A subsample of 250 cows from 5 herds were scored for live SLS and live locomotion by a third observer. Intra- and interobserver reliability for live SLS and live locomotion scoring were found to have a kappa coefficient of 0.53 (95% confidence limit = 0.43–0.64) when determining a cow as lame through SLS or locomotion scoring. Live SLS was correlated with live locomotion scoring (r = 0.92). However, lameness prevalence was lower when using live SLS (28.4%) compared with locomotion scoring (38%). In summary, live SLS may be an acceptable method to replace video SLS to identify lame cows and rank tie-stall herds in terms of lameness prevalence without having to remove the cows from their stalls or view videos to score; however, it may underestimate lameness prevalence compared with locomotion scoring methods.     

Effects of breed and production system on lameness parameters in dairy cattle

The aim of the present study was to assess the effects of Holstein-Friesian (HF) and Norwegian (N) dairy cattle genotypes on lameness parameters in dairy cattle within different production systems over the first 2 lactations. Following calving, HF (n = 39) and N (n = 45) heifers were allocated to 1 of 3 systems of production (high level of concentrate, low level of concentrate, and grass-based). High- and low-concentrate animals were continuously housed indoors on a rotational system so that they spent similar amounts of time on slatted and solid concrete floors. Animals on the grass treatment grazed from spring to autumn in both years of the study, so that most animals on this treatment grazed from around peak to late lactation. Claw health was recorded in both hind claws of each animal at 4 observation periods during each lactation as follows: 1) −8 to 70 d postcalving, 2) 71 to 150 d postcalving, 3) 151 to 225 d postcalving, and 4) 226 to 364 d postcalving. Sole lesions, heel erosion, axial wall deviation, sole length of the right lateral hind claw (claw length), right heel width, and right lateral hind heel height were recorded as well as the presence of digital dermatitis. The N cows had lower (better) white line and total lesion scores than HF cows. Cows on the high- and low-concentrate treatments had better sole and total lesion scores than cows on the grass treatment. The HF cows had better locomotion scores than N cows. Breed and production system differences were observed with respect to claw conformation, including claw length, heel width, and heel height. Digital dermatitis was associated with worse sole lesion scores and interacted with production system to influence white line lesion scores and maximum heel erosion scores. This study shows that genetic, environmental, and infectious factors are associated with hoof pathologies in dairy cows.     

Including milk production,conformation, and functional traits in multivariate models for genetic evaluation of lameness

Lameness is a serious health and welfare issue that can negatively affect the economic performance of cows, especially on pasture-based dairy farms. However, most genetic predictions (GP) of lameness have low accuracy because lameness data are often incomplete as data are collected voluntarily by farmers in countries such as Australia. The objective of this study was to find routinely measured traits that are correlated with lameness and use them in multivariate evaluation models to improve the accuracy of GP for lameness. We used health events and treatments associated with lameness recorded by Australian farmers from 2002 to early 2019. The lameness incidence rates in Holstein and Jersey cows were 3.3% and 4.6%, respectively. We analyzed the records of 36 other traits (milk production, conformation, fertility, and survival traits) to estimate genetic correlations with lameness. The estimated heritability ± standard error (and repeatability ± standard error) for lameness in both Holstein and Jersey breeds were very low: 0.007 ± 0.002 (and 0.029 ± 0.002) and 0.005 ± 0.003 (and 0.027 ± 0.006), respectively, in univariate sire models. For the GP models, we tested including measurements of overall type to prediction models for Holsteins, stature and body length for Jersey, and milk yield and fertility traits for both breeds. The average accuracy of GP, calculated from prediction error variances, were 0.38 and 0.24 for Holstein and Jersey sires, respectively, when estimated using univariate sire models and both increased to 0.43 using multivariate sire models. In conclusion, we found that the accuracy of GP for lameness could be improved by including genetically correlated traits in a multivariate model. However, to further improve the accuracy of predictions of lameness, precise identification and recording incidences of hoof or leg disorder, or large-scale recording of locomotion and claw scores by trained personnel should be considered.     

Genomic merit for reproductive traits. II: Physiological responses of Holstein heifers

Fertility traits were recently added to the evaluation of genetic merit, allowing for the selection of Holstein cattle with improved reproductive performance. In the current study, we investigated the associations among genomic merit for daughter pregnancy rate (GDPR) and heifer conception rate (GHCR) and physiological responses during proestrus and diestrus. Holstein heifers (n = 99) were classified based on GDPR [high = 3.26 ± 0.76 (1.6 to 5.3), n = 48; low = ?0.17 ± 0.75 (?1.8 to 1.0), n = 51] and GHCR [high = 2.75 ± 0.77 (1.5 to 5.5), n = 49; low = 0.06 ± 0.67 (?2.1 to 1.2), n = 50]. Heifers were fitted with an automated estrous detection device, were treated with PGF_2α for synchronization of estrus, and received either artificial insemination or embryo transfer at detected estrus. Blood was sampled at the time of PGF_2α treatment, within 24 h of the onset of estrus (d 0), and on d 7, 14, 19 ± 2, 28, and 35. Blood samples from all heifers were analyzed for concentrations of estradiol (d 0) and progesterone (on the day of PGF_2α treatment and d 0, 7, and 14). Blood samples from heifers pregnant on d 38 ± 3 were analyzed for concentrations of progesterone (d 0, 7, 14, 19 ± 2, 28, and 35), pregnancy-specific protein B (d 19 ± 2, 28, and 35), and insulin-like growth factor 1 (d 0, 7, 14, 19 ± 2, 28, and 35). Expression of mRNA for interferon-stimulated gene 15 in peripheral leukocytes isolated from blood collected on d 19 ± 2 was determined. Ovaries were scanned by ultrasound daily from d 0 to 4 or until ovulation was detected. Heifers with low GHCR tended to be less likely to be detected in estrus (78.0 vs. 91.8%). Estradiol concentration on d 0 was greater for heifers with high GDPR (4.53 ± 0.23 vs. 3.79 ± 0.23 pg/mL). The ovulatory follicle was larger for heifers with high GDPR (16.28 ± 0.33 vs. 14.55 ± 0.35 mm), whereas heifers with high GHCR tended to have smaller ovulatory follicles (15.00 ± 0.31 vs. 15.83 ± 0.37 mm). Heifers with high GDPR tended to be more likely to ovulate within 96 h of the onset of estrus (90.7 vs. 75.0%). Among heifers pregnant on d 38 ± 3, GDPR and GHCR were not associated with mRNA expression for interferon-stimulated gene 15. Heifers with high GDPR had greater concentration of pregnancy-specific protein B from d 28 to 35 (3.03 ± 0.15 vs. 2.48 ± 0.1 ng/mL). Heifers with high GHCR tended to have greater insulin-like growth factor 1 concentration from d 7 to 35 (108.0 ± 3.2 vs. 97.7 ± 4.2 ng/mL). Our results suggest that selection for Holstein cattle for GDPR may have positive effects on reproductive performance through changes in ovarian follicle development and steroidogenesis. Although selection of Holstein cattle for GHCR may negatively affect estrous expression by affecting ovarian follicle growth, selection for GHCR may improve reproductive performance by altering the somatotropic axis.     

Claw hardness of dairy cows: relationship to water content and claw lesions

Lameness of dairy cows is a major welfare and economic problem. Degree of hardness of claws may influence chances for injury or for claw lesions, and exposure of claws to moisture may make them soft. To assess the relationship among hardness of the claw horn, quantity and rate of absorption of water, and incidence of claw lesions, 4 experiments were carried out. In the first 3 experiments, we soaked pieces of the claw horn in water for 12 to 24 h. Soaked claws gained weight and became significantly softer, indicating that water was absorbed. One-third of the total water absorbed in 24 h occurred during the first hour. Base of the abaxial and dorsal walls of the claw was harder than the sole, but became softer more rapidly when soaked in water. In the 4th experiment, significant negative correlations were detected between claw hardness of cows and severity of claw lesions, suggesting that cows with softer claws have the most severe claw lesions. Claw horn tissue absorbs water rapidly and claw hardness decreases with moisture content, suggesting that brief exposures to moist surfaces result in claws that absorb water and consequently become softer. The relationship between hardness and claw lesions indicates that cows with softer claws are at greater risk for lameness.     

A prospective cohort study of digital cushion and corium thickness. Part 2: Does thinning of the digital cushion and corium lead to lameness and claw horn disruption lesions?

The aim of this study was to determine whether a decrease in thickness of the sole soft tissues (SST) beneath the flexor tuberosity of the distal phalanx (i.e., the digital cushion and corium) predisposed a claw to develop claw horn disruption lesions (CHDL) or a leg to lameness. Data were analyzed from a longitudinal study of 179 cows, which had been examined at 5 assessment points ?8, +1, +9, +17, and +29 wk relative to their first, second, third, or fourth calving. At each assessment point, SST were measured using ultrasonography. Additional assessment point data included sole lesions and back fat thickness (BFT), and cows had been locomotion scored every 2 wk from calving. One hundred fifty-eight cows completed the study. Separate logistic regression survival analyses were constructed to assess the outcomes, either lameness on a leg or CHDL on a claw; combinations of lameness and lesions were tested as outcomes. Cow level variables tested included farm and lactation number. Variables were tested describing previous SST thickness, minimum previous SST thickness, BFT, and change in either variable between prior assessment points. Prior lesions/lameness strongly predicted repeat cases and the final models had the outcome first lesion or lameness on a claw or leg. In the reported lameness models, lameness was defined as a leg being recorded as lame twice within 3 consecutive scores, and in the reported lesion models, lesion was defined as the first presence of either a sole ulcer or a severe sole hemorrhage on a claw. Thin SST increased the likelihood of lesion occurrence; thin SST on the lateral claw predicted subsequent lameness on a leg. Thin BFT and thinning of BFT between previous assessment points increased the likelihood of future lesion occurrence. Thin SST and thinning of BFT had additional effects on the likelihood of lesion occurrence, suggesting that BFT and sole SST had independent effects on lesion occurrence. However, change in SST thickness between assessment points did not influence the likelihood of future lesions or lameness. This suggests that thin SST were not simply a result of depletion of body fat and challenges the theory that thinning of the digital cushion with body fat mobilization leads to CHDL. Other possible mechanisms by which SST become thin are discussed and could include changes in integrity of the suspensory apparatus with physiological events.     

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.     

Analysis of foot health records from 17 confinement dairies

Foot health records are useful in monitoring the degree of lameness within dairy herds and, perhaps more importantly, providing insight into the underlying factors causing lameness. A database containing the incidence of foot lesions on large confinement dairy operations is largely unavailable but could prove useful to demonstrate the importance of collecting and analyzing foot lesion data to reduce lameness. Our objective was to merge foot lesion records from several dairy herds and establish a database to demonstrate how to use such data to better understand when and why foot lesions occur as an important means to manage lameness in dairy herds. The database consisted of 12 mo of records from 17 dairies (14 freestall, 1 combination dirt lot and freestall, 2 dirt lot) representing 58,155 cows from herds ranging in size from 631 to 9,355 animals in 9 states from the United States and 2 herds located in the Southern Hemisphere. Data were partitioned and analyzed as 2 separate data sets: (1) herds recording only lame events (cows lame when examined; n = 8), and (2) herds recording both lame and routine trim events (n = 9). Data were analyzed using PROC FREQ (SAS Institute Inc., Cary, NC) and significance was determined using Chi-square. White line disease, sole ulcer, toe ulcer, digital dermatitis, and foot rot comprised 93 and 40% (excluding routine trim with no lesion, 55%) of lesions for herds recording only lame events and those recording lame and trim events, respectively. Ratio of infectious to noninfectious lesions decreased with increasing lactation number in both data sets. Digital dermatitis and foot rot were greatest in the first 60 d in milk and differed across lactation number. Noninfectious lesions were greatest following summer heat stress, whereas infectious lesions were greatest during the coolest quarter of the year. In conclusion, analysis of the foot health data from these dairies demonstrates that (1) infectious lesions of the foot skin and soft tissues predominate in early lactation and during cooler months of the year, and (2) noninfectious lesions predominate during the 3 mo following summer heat stress and their distribution follows a typical lactation curve.