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.     

Short communication: Adipocyte sizes in the digital fat pad and their relationship to body condition in dairy cows

Lameness and body condition are closely related. Recent studies have shown that cows with low body condition score (BCS) have a greater risk for developing lameness than cows with higher BCS. Among other reasons, this relationship might be related to the reduced thickness of the digital fat cushion in lean cows. The digital cushion is not a homogeneous structure but consists of different fat pads and connective tissue. We hypothesized that either high or low BCS will result in concordant adipocyte sizes in the fat pads of the digital cushion and subcutaneous tailhead fat irrespective of the localization of the latter. Right front claws were collected from 18 Holstein Friesian cows. Cows were selected according to their BCS: 9 cows with BCS <3 (low BCS) and 9 cows with BCS ≥3 (high BCS). After dissecting the horn capsule of the lateral claw, samples of the axial and abaxial fat pads were prepared for histomorphological examinations (adipocyte size measurement) and protein abundance of vascular endothelial growth factor A (VEGF-A) via Western blotting. In addition, fat samples were excised from the tailhead of all cows and used for the same purposes. Adipocyte size in tailhead fat was greater in high-BCS than in low-BCS cows. Similar differences between the BCS groups were apparent for adipocytes from the axial fat pad, although adipocytes in tailhead fat were larger than those in the digital cushion. In contrast to that in the axial fat pad and tailhead fat, adipocyte size in the abaxial fat pad was similar in cows from both BCS groups. A relationship between adipocyte size and VEGF-A protein was only confirmed for the axial fat pad, not for the other fat depots. When comparing BCS groups, differences in VEGF-A protein abundance between high-BCS and low-BCS cows were also limited to the axial fat pad, being absent in tailhead fat and the abaxial fat pad. Taken together, our results show that the fat pads from the digital cushion should not be considered uniform adipose tissue locations but rather discrete units reacting differently to fat mobilization.     

Effects of alley and stall surfaces on indices of claw and leg health in dairy cattle housed in a free-stall barn

A 15-wk 2 x 3 factorial trial in a university dairy herd compared the effects of two alley surfaces and three free-stall beds on indices of lameness. Alley surfaces were grooved concrete (Ct) or 1.9-cm-thick interlocking rubber mats (R). Stalls were deep sand (S), rubber mattresses (M), or concrete (C). Mattress and concrete stalls were bedded with sawdust. At wk 1 and 15, the hind claws and hocks of 120 primi- (n = 69) and multiparous (n = 51) cows were scored for lesions and three claw measurements (dorsal wall length, heel depth, and toe angle) were recorded. Rates of lateral and medial claw growth and wear were calculated by measuring the migration of a reference mark away from the coronet. Digital photographs of claw surfaces were used to rescore claw lesions. Clinical lameness was evaluated by assigning a locomotion score from 1 to 4 to each cow during wk 1, 5, 10, and 14. Digital dermatitis (present/not present) and interdigital dermatitis (mild, moderate, or severe) were recorded at wk 15. The number of days that cows spent in a hospital barn was recorded. Before assignment, cows were professionally foot trimmed, sorted by initial claw lesion score, and then randomized in consecutive blocks of three to stall treatments. Photograph scores were highly repeatable. Nonparametric statistical techniques were used for analyses of rank data. Claw lesion score increased significantly for all treatment groups except RC and RS; however, when early lactation cows were excluded, no differences were found between treatment groups. Hock scores increased significantly more for cows in CtC than in CtS or RS. Significantly more animals from RC spent more than 10 d in the hospital pen compared with RM and RS. Groups did not significantly differ for clinical lameness. Cows in RS and RC had significantly lower rates for lateral claw net growth than those in CtM. Having moderate or severe interdigital dermatitis at wk 15 was associated with greater increases in claw lesion score and more treatments for digital dermatitis. All claw measurements were correlated; however, toe angle was most strongly correlated with the other two. In this experiment, stall and alley configurations did not lead to significant differences in several indices of lameness.     

Lameness in dairy cattle: A debilitating disease or a disease of debilitated cattle? A cross-sectional study of lameness prevalence and thickness of the digital cushion

Lameness is the most significant challenge for the dairy industry to overcome, given its obvious disruption of animal welfare and severe economic losses. Sole ulcers and white line abscesses are ubiquitous chronic diseases with the highest associated economic losses among all foot lesions. Their underlying causes are still not fully understood. An observational cross-sectional study was carried out to investigate the association between claw horn lesions and the thickness of the digital cushion. The thickness of the digital cushion was evaluated by ultrasonographic examination of the sole at the typical ulcer site. A total of 501 lactating Holstein dairy cows were enrolled in the study. The prevalence of sole ulcers was 4.2 and 27.8% for parity 1 and parity >1, respectively. The prevalence of white line disease was 1.0 and 6.5% for parity 1 and >1, respectively. The prevalence of lameness (visual locomotion score ≥3) was 19.8 and 48.2% for parity 1 and >1, respectively. The prevalence of sole ulcers and white line diseases was significantly associated with thickness of the digital cushion; cows in the upper quartile of digital cushion thickness had an adjusted prevalence of lameness 15 percentage points lower than the lower quartile. Body condition scores were positively associated with digital cushion thickness. The mean gray value of the sonographic image of the digital cushion had a negative linear association with digital cushion thickness (R² = 0.14), indicating that the composition of the digital cushion may have changed with its thickness. Furthermore, digital cushion thickness decreased steadily from the first month of lactation and reached a nadir 120 d after parturition. These results support the concept that sole ulcers and white line abscesses are related to contusions within the claw horn capsule and such contusions are a consequence of the lesser capacity of the digital cushion to dampen the pressure exerted by the third phalanx on the soft tissue beneath.     

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.     

A prospective cohort study of digital cushion and corium thickness. Part 1: Associations with body condition,lesion incidence,and proximity to calving

Claw horn disruption lesions (CHDL) are a major cause of lameness in dairy cattle and are likely a result of excessive forces being applied to the germinal epithelium that produces the claw horn. The digital cushion is a connective tissue structure, containing depots of adipose tissue, that sits beneath the distal phalanx and has been shown to be thicker in fatter cows. Body condition score (BCS) loss is a risk factor for CHDL, and one possible explanation is that fat is mobilized from the digital cushion during negative energy balance, causing the digital cushion to thin and lose force-dissipating capacity, leading to disruption of claw horn growth. This prospective cohort study investigated the association between measures of body fat and sole soft tissue (SST) thickness (a combined measure of the corium and digital cushion beneath the distal phalanx) in a longitudinal manner. The SST of 179 cows in 2 high-yielding dairy herds were measured at 5 assessment points between 8 wk before and 35 wk postcalving. The BCS, back fat thickness (BFT), and lesion incidence were recorded. Data were analyzed in a 4-level mixed effects regression model, with the outcome being SST thickness beneath the flexor tuberosity of the distal phalanx. Data from 827 assessment points were available for analysis. The overall mean of SST was 4.99 mm (standard deviation: 0.95). The SST was thickest 8 wk before calving (5.22 mm, standard deviation: 0.91) and thinnest 1 wk postcalving (4.68 mm, standard deviation: 0.87), suggesting an effect of calving on SST. The BFT was positively correlated with SST in the model with a small effect size (a 10 mm decrease in BFT corresponded with a 0.13 mm decrease in SST), yet the nadir of BFT was 11.0 mm at 9 to 17 wk postcalving (when SST was ～4.95 mm), rather than occurring with the nadir of SST immediately after calving. The SST also varied with other variables [e.g., cows that developed a sole ulcer or severe sole hemorrhage during the study had thinner SST (?0.24 mm)], except when a sole ulcer was present, when it was thicker (+0.53 mm). Cows that developed lesions had a thinner digital cushion before the lesion occurrence, which became thickened with sole ulcer presence, perhaps representing inflammation. Furthermore, although BFT was correlated with SST over time, SST may also have been influenced by other factors such as integrity of the suspensory apparatus, which could have a major effect on CHDL. Measures of body fat likely contributed to having thin SST, but other factors including calving, herd, and lesion presence also had an effect.     

Bovine claw and limb disorders at claw trimming related to milk yield

As part of a cross-sectional study of Norwegian Red Cattle, associations of lameness, lesions at the tarsus, claw shapes, claw lesions, and claw trimming with milk yield were examined. Fifty-five tie-stall herds and 57 free-stall herds were sampled by computerized systematic selection, and 2,665 cows were trimmed and limb and claw disorders recorded. After exclusions, 2,599 cows were included in this study. Monthly recordings of milk were extracted from the Norwegian Dairy Herd Recording System. Most claw lesions were mild (score 1). The prevalence of moderate and severe lesions (score 2 and 3) did not exceed 5% for any of the lesions. Associations with test-day milk yield were identified using regression analyses (Proc Mixed) with repeated measurements within lactation and herd as random effect. Lactation curves were fit to visualize differences in changes in milk yield throughout the lactation. Milk yield was generally higher in cows with lesions at the tarsus, heel-horn erosions, and hemorrhages of the white line and the sole than in cows without these lesions, whereas cows with dermatitis yielded less than cows without dermatitis. Cows in lactation 1 with corkscrewed claws had reduced milk yield, whereas cows in lactations 2 and above had increased milk yield compared with cows without corkscrewed claws in respective lactations. Cows in lactation 1 yielded 0.47 ± 0.15 kg and cows in later lactations yielded 0.51 ± 0.15 kg more milk on test days after claw trimming than they did before when adjusted for days in milk. In this study, where most disorders were mild, the most evident results were higher milk yield in cows with lesions at the tarsus, heel-horn erosions, and hemorrhages of the white line and the sole than in cows without these lesions. Cows yielded more milk after claw trimming than they did before trimming.     

Moisture content, thickness, and lesions of sole horn associated with thin soles in dairy cattle

Thin soles and resulting lameness are often associated with increased culling rates in large dairy operations. The moisture content of the sole horn may cause the horn to be softer, thus predisposing it to an increased rate of wear. For that reason, the first objective of this study was to determine the moisture content of the sole horn of thin-soled cows. The second objective was to document physical changes of the claw associated with thin soles. Twenty-six adult Holstein cows showing signs of thin soles, and 16 normal cows were used in the study. Selection criteria for thin-soled cows included a dorsal wall length of less than 7.5 cm and the following clinical signs: painful gait, arched back, and specific leg lameness. Sixteen normal adult cows with dorsal wall length in excess of 7.5 cm were randomly selected. For thin-soled cows, the moisture contents of sole horn were 37.1 +/- 0.7% for front claws and 40.5 +/- 0.7% for rear claws. These values were significantly different from each other. Moisture contents of sole horn from normal cows were 31.08 +/- 0.93% for front claws and 33.1 +/- 0.9% for rear claws, which were significantly different from each other and different from thin-soled cows. Rear claws had higher moisture contents than front claws. Mean sole horn thickness was 4.23 +/- 0.18 mm for the rear lateral claws and 5.15 +/- 0.18 mm for the rear medial claws. The average dorsal wall lengths were 66.8 +/- 3.94 mm for rear lateral claws and 69.1 +/- 7.25 mm for rear medial claws. Thirty percent of rear feet with thin soles had pathological claw horn lesions including sole/white line separation (72%) and sole ulcers (28%). Of the affected claws, 13% had more than one lesion. Seventy-seven percent of claw lesions occurred in the lateral claw.     

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.     

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.     

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.     

Mechanical properties of the bovine claw horn during lactation

Claw horn disorders are one of the main causes of lameness in dairy cows globally. This study aimed to develop material testing techniques to assess changes in the mechanical properties of bovine claw horn (BCH) and to compare these mechanical properties with existing methods of assessing claw horn disorders during lactation. Lameness was also measured through locomotion scoring to assess the clinical significance of changes observed in the scoring for lesions. Experiment 1 used 8 claws collected from four 12 to 18 mo old beef heifers, to develop BCH sample storage methods and techniques to test the mechanical properties of BCH (puncture resistance and elastic modulus). The increase in the moisture content of BCH had a significant negative exponential effect on the elastic modulus of the sole and white line claw horn and a linear reduction in the puncture resistance of BCH. Placing BCH samples in sealed plastic bags and storing them either at 2°C or by freezing samples at -22°C did not alter the dry matter content and, consequently, the mechanical properties of the claw horn tissue. In experiment 2, BCH was collected from 36 lactating dairy cows and mechanical properties were tested using puncture resistance. Puncture resistance of the sole area of the claw horn decreased significantly when hemorrhages in the tested area increased. The puncture resistance of the sole and white line areas decreased at d 160 postpartum when the cows exhibited higher lesion scores and was lower in hind claws that had higher lesion scores when compared with the fore claws. The highest puncture resistance was found at 270 d postpartum, when the animals were at pasture. Puncture resistance was found to be an effective technique for assessing the effect of period of lactation and increasing hemorrhage levels on the mechanical properties and structural strength of bovine claw horn. It was found to be a good method of comparing changes and differences in mechanical properties and structural strength of BCH from the sole and white line areas within each claw and differences between claws. White line BCH consistently had significantly lower puncture resistance compared with the sole. Bovine claw horn with greater levels of hemorrhage or lower puncture resistance, or both, may provide less protection and increase the risk of foreign body penetration, trauma, and secondary infection of the corium of the claw.     

Altering the fatty acids in milk fat by including canola seed in dairy cattle diets

The objective was to evaluate the effects of feeding ground canola seed on the fatty acid profile, yield, and composition of milk from dairy cows. Twenty-four multiparous Holstein cows (548.3 ± 11.9 kg body weight and 28 ± 9 d in lactation) were randomly assigned to 1 of 2 treatments: Control (CON) or ground canola seed treatment (GCS) with 14% [of diet dry matter (DM)] of the total ration as ground canola seed containing 34% lipid. Diets contained 20% crude protein, but varied in net energy as a result of fat content differences of 2.5% and 6.4% (DM) for CON and GCS, respectively. Diets were composed of corn, corn silage, alfalfa (50:50 ground hay and haylage, DM basis), soybean and blood meal, and vitamins and minerals. Mechanically extruded canola meal was used in the CON diet to adjust for the protein from canola seed in the GCS diet. Cows were housed in tie-stalls and fed and milked twice daily for 10 wk. The inclusion of ground canola seed did not alter DM intake, weight gain, or body condition score of cows. Milk fat from GCS cows had greater proportions of long-chain fatty acids (≥18 carbons) and a lower ratio of n-6 to n-3 fatty acids. Feeding GCS reduced the proportion of short- and medium-chain fatty acids. Milk fat from cows fed GCS had a greater proportion of vaccenic acid and tended to have a higher proportion of cis-9,trans-11 conjugated linoleic acid. Actual and 3.5% fat-corrected milk yields were similar between treatments. The milk fat and protein percentages were lower for GCS cows, but total yield of these components was similar between treatments. Milk urea nitrogen was lower and serum urea nitrogen tended to be lower in cows fed canola seed. Serum glucose, insulin, and nonesterified fatty acids were not altered, but serum triglycerides were higher in GCS cows. Ammonia and total volatile fatty acids tended to be lower in ruminal fluid from GCS cows; rumen pH was unchanged. Feeding canola seed to lactating dairy cows resulted in milk fat with higher proportions of healthful fatty acids without affecting milk yield or composition of milk.     

Effect of isoflupredone acetate with or without insulin on energy metabolism, reproduction, milk production, and health in dairy cows in early lactation

Glucocorticoids are commonly used to treat cows with clinical ketosis and fatty liver disease, but their use is controversial. The objectives of the present study were to investigate the effects of isoflupredone acetate alone or with insulin on the energy metabolism of dairy cows in early lactation in a large double-blind, randomized clinical trial. A total of 1,162 Holstein cows and first-lactation heifers were randomly assigned to receive 1 of 3 treatments between the day of parturition and 8 DIM: group A, 20 mg i.m. injection of isoflupredone and 100 units of insulin; group B, 20 mg i.m. injection of isoflupredone; group C (control group), 10 mL i.m. injection of sterile water. Treatments were randomized across 24 dairy farms located near Guelph, Ontario, Canada. Serum samples obtained at the time of treatment and at wk 1 and 2 following treatment were analyzed for β-hydroxybutyrate, nonesterified fatty acids, glucose, calcium, potassium, sodium, and chloride. Cows were assigned a body condition score at the time of enrollment. Data were analyzed using a repeated-measures mixed model that accounted for the effects of parity and body condition score, and the random effects of cow and farm. Cows that received isoflupredone with insulin and isoflupredone alone had higher β-hydroxybutyrate and nonesterified fatty acid concentrations 1 wk after treatment compared with control cows. Cows that received isoflupredone acetate plus insulin had lower glucose concentrations at 1 wk after treatment. Calcium concentrations 1 wk after treatment were lower for cows that received isoflupredone and insulin or isoflupredone only compared with control cows. Serum sodium, potassium, and chloride concentrations were not influenced by treatment. The effect of treatment on the proportion of cows with subclinical ketosis was evaluated with a logistic regression model. Over the 2 wk following treatment, a significant increase in the prevalence of subclinical ketosis was observed in the isoflupredone plus insulin group relative to the control group. Among 972 cows that were not ketotic at enrollment, cows that received isoflupredone acetate plus insulin or isoflupredone acetate only were, respectively, 1.72 and 1.59 times more likely than control cows to develop subclinical ketosis 1 wk after treatment. There were no treatment effects on test-day milk production, milk fat and protein percentages, or the intervals from calving to first insemination or pregnancy.     

Genetic parameters for claw disorders in Dutch dairy cattle and correlations with conformation traits

Impaired claw health is one of the major problems causing production loss and reduced animal welfare in dairy cattle. In response, the Dutch Animal Health Service (GD) Ltd. initiated this study, in which claws of lactating and near-term cows and heifers in 430 herds were trimmed by hoof trimmers and the health status of the rear claws recorded. Only herds with >75% of the animals having feet trimmed were considered, resulting in records on 21,611 animals. Eight claw disorders were scored: digital dermatitis (DD), interdigital dermatitis/heel horn erosions (IDHE), sole hemorrhage (SH), chronic laminitis (CL), sole ulcer (SU), white line disease (WLD), interdigital hyperplasia (HYP), and interdigital phlegmona (IP). The prevalence varied from 0.6% (IP) to 39.9% (SH). More than 70% of the animals had at least one claw disorder. Conformation traits and locomotion were recorded once during the animal's first lactation by trained classifiers of the Royal Dutch Cattle Syndicate and completely independent of the moment of claw trimming. Heritabilities were estimated using a sire model, and ranged from <0.01 (IP) to 0.10 (DD and HYP). Genetic correlations of incidences of claw disorders with locomotion were variable, ranging from 0.13 (SH) to −0.91 (CL). Genetic correlations with the rear leg conformation traits were lower, ranging from 0.04 (ID with rear leg side view) to −0.69 (IP with rear leg rear view).     

Hepatic fatty acid composition in periparturient dairy cows with fatty liver induced by intake of a high energy diet in the dry period

The present study compared the hepatic fatty acid composition of cows that were fed a high energy diet during the dry period to induce fatty liver after parturition with that of control cows. Treated cows had higher concentrations of plasma nonesterified fatty acids as a result of greater lipolysis after parturition than did control cows; consequently, the treated cows accumulated greater amounts of triacylglycerols in the liver. Before parturition, treated cows had lower percentages of oleic acid and higher percentages of linoleic acid than did control cows, but percentages of other fatty acids were similar for both groups. After parturition, percentages of each fatty acid were changed substantially, particularly the four major fatty acids (palmitic, stearic, oleic, and linoleic acids). For treated cows, the percentages of palmitic and oleic acids were higher at 0.5 wk after parturition than at 1 wk before parturition; percentages of stearic and linoleic acids decreased. Unlike treated cows, the percentages of both oleic and linoleic acids in the control cows did not change during that time. Moreover, we found that when lipolysis decreased, as indicated by lower plasma nonesterified fatty acid concentrations, the percentages of each fatty acid gradually rebounded toward the concentrations measured before parturition; this observation indicates that the shift in hepatic fatty acid composition is influenced by lipolysis. The increased lipolysis after parturition led to a vast increase in the hepatic triacyglycerol concentration and to a shift in hepatic fatty acid composition.     

Circulating low-density lipoprotein ceramide concentrations increase in Holstein dairy cows transitioning from gestation to lactation

Low-density lipoprotein (LDL) ceramide causes insulin resistance in obese diabetic nonruminants. Because previous work suggests that liver-derived ceramide may impair insulin action in postpartum cows, our objectives were to characterize peripartal changes in lipoprotein ceramides. We further studied the effects of prepartum adiposity on lipoprotein ceramide levels. Twenty-eight pregnant Holstein cows (parity = 3.65 ± 1.62) with lean (body condition score, BCS = 2.97 ± 0.16; body weight, BW = 630 ± 55.2 kg; n = 15) or overweight (BCS = 3.93 ± 0.27; BW = 766 ± 46.1 kg; n = 13) body condition 28 d before expected parturition were evaluated. Sampling occurred on d ?20.5 ± 1.74, ?13.8 ± 1.71, ?7.84 ± 4.07, ?6.71 ± 1.00, ?3.92 ± 0.64, and ?1.28 ± 0.61 (before parturition); daily until d 8 postpartum; and on d 10, 12, 14, 21, and 28. Adipose tissue and liver were biopsied on d ?7.84 ± 4.07 and 10. Postpartum insulin sensitivity was assessed using the hyperinsulinemic-euglycemic clamp. Lipoprotein fractions were isolated using liquid chromatography. Sphingolipids were quantified using mass spectrometry. Data were analyzed using a mixed model with repeated measures. Overweight cows had a higher BCS and BW at enrollment relative to lean cows, but BCS and BW were similar postpartum. Overweight cows lost more body condition (0.97 ± 0.36 vs. 0.55 ± 0.16 BCS units) and BW (291 ± 67.3 vs. 202 ± 54.5 kg) during transition relative to lean cows. Adipocyte volume and counts declined from prepartum to postpartum (50.4 and 13.7%, respectively), and adipocyte volume was greater (48.2%) in overweight cows prepartum relative to lean cows. Although DMI was comparable between BCS groups, milk yield tended to be greater in overweight cows. Plasma free fatty acid and β-hydroxybutyrate and liver lipid levels were 40, 16, and 37% greater, respectively, in overweight cows compared with lean cows. Glucose infusion rate during the hyperinsulinemic-euglycemic clamp tended to be lower in overweight cows. Ceramide levels within triacylglycerol-rich lipoprotein fractions declined postpartum, whereas LDL ceramide increased postpartum. Overweight cows had lower triacylglycerol-rich lipoprotein C16:0-ceramide levels relative to lean cows. Prepartum LDL C24:0-ceramide levels were greater in overweight cows relative to lean cows. Independent of prepartum adiposity, we concluded that serum LDL ceramide levels are elevated in early-lactation cows experiencing adipose tissue free fatty acid mobilization and hepatic steatosis.     

Effects of induced weight shift in the hind limbs on claw loads in dairy cows

The modern dairy industry is plagued by a high prevalence of claw horn lesions in cows, which cause lameness, affect well-being, limit milk production, and are responsible for premature removal of cows from the herd. The lateral hind claws are primarily affected, and this has been linked to a relatively higher load being exerted on the lateral claws when cows shift weight from one hind limb to the other. The vertical ground reaction forces and mean and maximum pressures under the claws were measured in 40 nonlame dairy cows before and during a shift in weight from one hind limb to the other, which was accomplished by applying pressure manually to one side of the pelvis. During square standing on firm ground, about two-thirds of the entire hind limb load was exerted on the 2 lateral claws, and the remaining one-third was exerted on the medial claws combined. At the moment of maximum weight shift, the lateral claw of the loaded limb bore almost two-thirds of the entire load of both hind limbs, with the heel zone bearing almost half of the load of both hind limbs. Subsequently, the load of the lateral claw of the contralateral hind limb decreased, as did the load of both medial claws. Thus, the weight redistribution had occurred predominantly between the lateral hind claws. The high load exerted on a lateral hind claw during weight shift and at maximum weight shift is assumed to play a role in the pathogenesis of claw horn lesions, particularly when accentuated by a softened claw horn and hard flooring.     

Effect of different flooring systems on claw conformation of dairy cows

The effect of different flooring surfaces in walking and standing areas on claw conformation, claw horn growth, and wear was studied in 2 experiments during 2 consecutive housing seasons in a research dairy herd of 170 cows. In experiment 1, the flooring systems tested were solid rubber mats, mastic asphalt with and without rubber-matted feed-stalls, and aged concrete slats. In experiment 2, slatted concrete flooring was compared with slatted rubber flooring. The cows were introduced to the respective flooring systems in early lactation and their claws were trimmed before the exposure period. Toe length, toe angle, sole concavity, and claw width, as well as claw growth and wear rates were recorded for lateral and medial claws of the left hind limb. Claw asymmetry calculations were based on these claw measurements and on differences in sole protrusion between lateral and medial soles. Asphalt floors caused shorter toe length and steeper toe angle. They also increased wear on rear claws (5.30 ± 0.31 and 5.95 ± 0.33 mm/mo for lateral and medial claw, respectively; LSM ± SE) and horn growth rate (5.12 ± 0.36 and 5.83 ± 0.31 mm/mo of lateral and medial claws, respectively). Rubber mats instead of asphalt in walking areas reduced wear (1.36 ± 0.19 and 2.02 ± 0.20 mm/mo for lateral and medial claw, respectively) and claw growth (3.83 ± 0.23 and 3.94 ± 0.17 mm/mo for lateral and medial claw, respectively). Rubber-matted feed-stalls together with asphalt walkways decreased claw wear (3.29 ± 0.31 and 4.10 ± 0.32 mm/mo for lateral and medial claw, respectively). The concavity of claw soles was reduced on asphalt, especially in the lateral rear claws. Rubber matting in feed-stalls prevented loss of sole concavity compared with asphalt. Claw asymmetry did not differ between flooring systems. While different access to abrasive flooring affected claw conformation, there was no evidence that flooring system influenced the disproportion between lateral and medial claws.     

Objective determination of claw pain and its relationship to limb locomotion score in dairy cattle

We hypothesized that claw and foot pain could be objectively determined and have a strong effect on limb locomotion. Claw pain was measured using hoof testers equipped with a pressure gauge. Soft tissue pain was evaluated with an algometer. Pain was determined as the maximum pressure recorded at the time the limb was withdrawn following claw or soft tissue compression with the hoof tester or algometer. Locomotion scores and claw and soft tissue pain were determined on 263 Holstein cows from 2 commercial dairy farms. The frequency and the magnitude of pain had an effect on locomotion score in the ipsilateral limb for lateral, but not medial, claws. The magnitude of the lateral claw pain index for limbs with locomotion scores 1 to 5 was 0.95 ± 0.01, 0.90 ± 0.02, 0.67 ± 0.04, 0.65 ± 0.05, and 0.45 ± 0.11, respectively. The magnitude of the medial claw pain index for limbs with locomotion scores 1 to 5 was 1.0 ± 0.00, 0.99 ± 0.01, 0.98 ± 0.01, 1.0 ± 0.00, and 1.0 ± 0.00, respectively. The frequency of painful claws (n = 208) in limbs with locomotion scores 1, 2, and ≥3 was 0.529, 0.173, and 0.298, respectively. The frequency of painless claws (n = 318) in limbs with locomotion scores 1, 2, or ≥3 was 0.792, 0.088, and 0.120, respectively. The frequency of pain (27.1%) and total lesions (85.6%) was greater in lateral claws (n = 524) than that of pain (2.1%) and total lesions (14.4%) in medial claws (n = 524). Yet the magnitude of the pain index in sore claws was similar for medial (0.73 ± 0.09) and lateral claws (0.64 ± 0.02). The magnitude and frequency of claw pain in one hind limb was inconsistently and weakly affected by locomotion score or claw pain in the contralateral limb. The prevalence of unilateral (32.8%) and bilateral (23.3%) pain was similar and lower than the occurrence of bilaterally nonpainful claws (43.9%) in the study group. Painful claws (n = 78) occurred on sound limbs (n = 332) with a pain index (0.72 ± 0.02) indicative of less pain than the pain index (0.61 ± 0.02) of painful claws (n = 130) on lame limbs (n = 192). The results showed that lateral claw pain was related to ipsilateral limb locomotion score and subclinical pain was a relatively common occurrence. Objective measures of pain may provide a more reliable, continuous measure of clinical events used in modeling lameness.