No abstract

Data were collected prospectively for 1.5 yr on two New York dairy farms to investigate the effect of lameness on milk production. The numbers of study cows (percentages treated at least once for lameness) in each herd were 1796 (52%) and 724 (40%), respectively. Lame cows were identified and treated by farm employees or a professional hoof trimmer. Weekly averages of total milk production per day were recorded based on automated milk weight measurements at each milking. The effect of lameness on milk production was analyzed separately for each herd using repeated measures ANOVA. In both herds, milk production decreased significantly for cows diagnosed lame. Milk production was 1.5 kg/d lower > or = 2 wk after lameness compared with cows that had not yet been diagnosed lame in the current lactation in the larger herd. In the second herd, milk production of lame cows was 0.8 kg/d lower in the first and second wk after lameness and 0.5 kg/d lower > or = 3 wk after diagnosis. The decrease in milk production associated with lameness was larger for cows in second or greater lactation and for more severe cases. In one herd, the decrease in milk production was greater for cows with sole ulcers or foot abscesses than for foot rot or foot warts. Cows with abscesses or foot rot tended to have larger decreases in milk production in the other herd. The inconsistent results between farms may have resulted from differences in the relative frequencies of specific causes of lameness in the two herds and in the way lame cows were identified and defined for the study.

The purpose of this study was to assess the effect of lameness on dairy cow survival. Cox's proportional hazards regression models were fitted to single-lactation data from 2520 cows in 2 New York State dairy herds. Models were controlled for the time-independent effects of parity, projected milk yield, and calving season, and for the time-dependent effects of lameness and culling. Other common diseases were found to be nonconfounding and so were not included in any of the final models. Survival was measured as the time from calving until death or sale. Cows were censored if they reached the start of the next lactation or end of the study, whichever occurred first. All models were stratified by herd. For all lameness diagnoses combined, survival in the herd decreased for those cows becoming lame during the first half of lactation, with a hazard ratio of up to 2 times that of a nonlame cow. Foot rot diagnosed during the second or third months of lactation decreased survival during the same time period (hazard ratio=5.1; 95% confidence interval=1.6 to 16.2). Sole ulcers diagnosed in the first 4 mo of lactation decreased survival in several subsequent periods in which the strongest association was between diagnosis in the third and fourth months of lactation and exit from the herd during that same period (hazard ratio=2.7; 95% confidence interval=1.3 to 6.0). Foot warts were not associated with decreased survival in this analysis. Lameness was never associated with increased survival in any of the models.

Bovine digital dermatitis (DD) is the most important infectious disease associated with lameness in cattle worldwide. Since the disease was first described in 1974, a series of Treponema species concurrent with other microbes have been identified in DD lesions, suggesting a polymicrobial etiology. However, the pathogenesis of DD and the source of the causative microbes remain unclear. Here we characterized the microbiomes of healthy skin and skin lesions in dairy cows affected with different stages of DD and investigated the gut microbiome as a potential reservoir for microbes associated with this disease. Discriminant analysis revealed that the microbiomes of healthy skin, active DD lesions (ulcerative and chronic ulcerative) and inactive DD lesions (healing and chronic proliferative) are completely distinct. Treponema denticola, Treponema maltophilum, Treponema medium, Treponema putidum, Treponema phagedenis and Treponema paraluiscuniculi were all found to be present in greater relative abundance in active DD lesions when compared with healthy skin and inactive DD lesions, and these same Treponema species were nearly ubiquitously present in rumen and fecal microbiomes. The relative abundance of Candidatus Amoebophilus asiaticus, a bacterium not previously reported in DD lesions, was increased in both active and inactive lesions when compared with healthy skin. In conclusion, our data support the concept that DD is a polymicrobial disease, with active DD lesions having a markedly distinct microbiome dominated by T. denticola, T. maltophilum, T. medium, T. putidum, T. phagedenis and T. paraluiscuniculi. Furthermore, these Treponema species are nearly ubiquitously found in rumen and fecal microbiomes, suggesting that the gut is an important reservoir of microbes involved in DD pathogenesis. Additionally, the bacterium Candidatus Amoebophilus asiaticus was highly abundant in active and inactive DD lesions.

The objective of this study was to evaluate the association between uterine disease and indicators of neutrophil (PMN) and systemic energy status in dairy cows. Peripheral blood (120 mL) was collected weekly from 84 Holstein cows for PMN isolation and plasma collection from calving until 42 d in milk (DIM). The final analysis included 80 cows. Of those, 20 cows were classified as having metritis (fetid uterine discharge and fever), 15 as having subclinical endometritis (SCE; >or=10% PMN on uterine cytology), and 45 as healthy controls. Plasma haptoglobin concentration was increased only in cows that developed metritis. Neutrophil glycogen content was reduced in cows developing metritis compared with healthy cows on the day of calving and at 7 and 42 DIM. Cows with SCE had lower PMN glycogen content than healthy cows at 7, 28, and 42 DIM. Blood glucose was affected by disease status within parity. Primiparous metritis cows had greater blood glucose concentrations than healthy primiparous cows. Multiparous metritis cows tended to have lower blood glucose concentration than multiparous SCE cows. Cows that developed metritis and SCE had or tended to have greater NEFA and BHBA than healthy cows, mainly around calving. At calving, cows that developed metritis had higher plasma estradiol concentration than healthy cows and greater plasma cortisol than cows that had SCE. Plasma insulin was not affected. Plasma glucagon was increased for SCE cows. Cows that developed uterine disease experienced a greater degree of negative energy balance and had decreased lower intracellular PMN glycogen levels, which could be a major predisposing factor for disease because of decreased availability of oxidative fuels.

The objectives of this cross-sectional study were to determine herd-level and cow-level prevalence estimates for 11 foot lesions in Ontario dairy cattle. Foot lesions were recorded by 5 hoof trimmers on 13,530 cows in 204 Ontario dairy herds from March 2004 to May 2005. Significant differences existed between free-stall and tie-stall housing. In free-stall housing systems, 46.4% of cows had a foot lesion, compared with 25.7% of cows in tie-stall barns. Digital dermatitis was the most common lesion in tie stalls, occurring in 9.3% of cows and 69.7% of the herds, whereas in free-stall herds, 22.7% of cows and 96.7% of the herds were affected. The most common hoof horn lesions were hemorrhages and ulcers, at 7.7 and 4.7% in tie-stall housing and 11.0 and 9.2% in free-stall housing, respectively. Foot blocks were used to treat 2.2% of cows in free stalls and 0.3% in tie stalls. Intraclass correlation coefficients ranged from 9.5 to 17.3 for hoof horn lesions and 28.0 to 38.7 for infectious lesions. In summary, foot lesions diagnosed at the time of hoof trimming are common in Ontario, and appropriate treatment for hoof horn lesions is low.

Path analysis was used to model the direct and indirect relationships among age, previous lactation yield or estimated transmitting ability for milk, body weight, days dry, reproductive disorders, milk fever, mastitis, reproductive performance, current milk yield, and culling. Prospective data were from 784 primiparous and 2,066 multiparous Holstein lactations from 33 herds. Heifers that were older, of lighter weight, or who had lower estimated transmitting ability for milk had more problems, less milk, and poorer survival. Dystocia in heifers had several detrimental consequences including 2.9 to 4 times more retained placenta, metritis, and culling and +7.4 d more to first service. Cystic ovaries were associated directly with 376 kg greater milk yield and with a 16.5-d delay in first service. Failure to conceive at first service and mastitis increased risk of culling 5.2 to 10 times. In multiparous cows, milk fever increased risk of reproductive disorders by 1.6 to 4.2 times and indirectly contributed to poor breeding performance and increased culling. Risk of culling was increased 2.1 to 3.7 times directly by mastitis and dystocia and by poor breeding performance.

The effect of clinical mastitis on milk yield was studied in 24,276 Finnish Ayrshire cows that 4 calved in 1993 and were followed for one lactation (i.e., until culling or the next calving). Only cows 5 that had mastitis, but no other diseases and cows that had no diseases (healthy cows) during the 6 lactation were included in the study.