Performing Department
Veterinary Population Medicine
Non Technical Summary
Lameness is a painful, prevalent disease in the US dairy industry. Regular hoof trimming to remove overgrowth and rebalance the claws is viewed as an essential part of a lameness prevention program and is regularly practiced by the US dairy industry. Unfortunately, there is very little scientific evidence on which to base recommendations on the timing and technique of hoof trimming. The goal of this project is to provide sound scientific evidence for this. The overall hypothesis of this project is that by modifying the timing and hoof trimming technique the incidence of foot lesions and lameness will be reduced, thereby improving longevity, well-being and productivity. We will evaluate this hypothesis by recruiting four commercial dairy farms that will enroll a total of 1800 2nd lactation animals. These animals will be enrolled at time of dry-off in 2 different treatment groups. Each treatment group will contain 900 animals and followed until they are 100-150 DIM. The 2 trimming techniques evaluated will be the functional trimming method and an adaptation that removes more horn underneath the flexor tuberosity on the lateral claw. At 100-150 DIM cows will be reassigned into a trimmed and not trimmed group to evaluate the impact of trimming twice per lactation. Outcomes evaluated in this study will include: time to lameness, time to culling and lesion prevalence. Our objectives of evaluating the timing and technique of hoof trimming will provide evidence for preventive practices that will reduce animal stress and improve animal well-being through reduced lameness.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
Based on the widespread use of hoof trimming in the US dairy industry (NAHMS, 2009) and the lack of evidence for the effectiveness of hoof trimming techniques and timing, the goal of this project is to evaluate 2 different methods and schedules of hoof trimming in Holstein dairy cows.The overall hypothesis of this project is that by modifying the timing and trimming technique of dairy cows the incidence of foot lesions and lameness will be reduced, thereby improving longevity, well-being and productivity.The specific objectives of this project are:Compare the effects of 2 different methods of functional hoof trimming on hoof lesion incidence, lameness, and culling risk.Compare the effects of an additional hoof trimming at 100 days in milk on hoof lesion incidence, lameness, and culling risk.
Project Methods
To meet our objectives we will enroll 1800, 2nd lactation animals at time of dry-off. These animals will initially be randomly assigned into 2 different treatment groups. Animals with hoof horn lesions such as sole ulcers and white line disease at the time of enrollment will not be enrolled in the study. Animals with the infectious disease, digital dermatitis will be treated according to standard farm protocol and enrolled in the study. All cows will be evaluated at 100-150 DIM for hoof lesions in the hoof trimming chute and then randomly be assigned to a TRIM or NOTRIM group. At the end of their 3rd lactation all cows will then be trimmed at time of drying off.The sample size of 900 animals in each initial treatment group was used to allow a total of 588 animals in each treatment group to finish their 3rd lactation. With this sample size we would be able to detect a 7-8% difference in lesions incidence between treatment groups in 3rd lactation (assuming an alpha of 0.05% and a power of 80% at a control lesion incidence of 30%). This lesion reduction was based on the preliminary data generated by a member of our group (Gomez et al., 2013). Since the data from Gomez et al. (2013) looked at first lactation only and lesion incidence is higher in 3rd lactation (Chapinal et al., 2013b) it is expected that the difference between lesion incidence between our treatment groups will be higher and our sample size is appropriate. To account for higher culling in early lactation it was assumed that 20% of the cows would be culled before the mid lactation hoof trimming and the remaining 15% of cows would be culled the later stages of lactation. Figure 1 below illustrates the study allocation.The project will use 4 different farms located within 1-4 hours drive of Saint Paul, MN. Participating farms will be recruited through the use of hoof trimmers who are have previously been trained in the modelling technique. Farms will be required to subscribe to dairy herd improvement services and use unique individual identification. Farm characteristics will be standardized to be mainly Holstein, have >1000 cows and using sand bedding.Sand bedding has been showing to influence lameness prevalence (Espejo and Endres, 2007; Cook, 2003). This potentially limits the external validity of this study but, if a significant effect of trimming method and timing can be found in an environment that fosters a lower lesion incidence this would be a bias towards the null. It is therefore highly probable that if we find an effect of our interventions in these herds, a greater effect would exist in non-sand bedding herds. We chose the herd size selection criteria to allow us to complete study in a short time frame and reduce procedural drift.Figure 1: Schematic of study allocation and sample sizes, initial n assumes a 35% cull rate across the 3rd lactation.Hoof trimmers will have been trained previously about the MODEL technique will receive training at the beginning of the study to standardize the trimming technique among the different farms. The NOMODEL trimming technique will be the standard functional trimming technique (Shearer and van Amstel, 2001; E. Toussaint Raven, 1985) The MODEL trimming technique used is an adaptation of this technique and will be the same as described by (Gomez et al., 2013). This method is an adaptation of the method described by (Ouweltjes et al., 2009). Hoof trimmers will be provided with an electronic recording device to facilitate data recording and extraction. Other than recording cow identification and date of trimming the hoof trimmers will records the lesions in a standardized manner.After the initial training session the farm will be visited monthly for locomotion scoring using a 4-point scoring system (Cook, 2003), to determine an objective measurement of lameness prevalence between the treatment groups. Productivity data like milk production and culling data will be retrieved from on farm records and dairy herd improvement data.Methods of analysis and interpretation:To evaluate the efficacy of trimming method on lesion incidence, lameness and productivity of each treatment group they will be compared to each other. The measures used as primary outcomes in this study include clinical lameness incidence as recorded by on farm personnel, and lesion incidence as recorded by the hoof trimmer at the time of trimming. Lesions of primary interest are digital dermatitis (DD), sole ulcers (SU) and white line disease, (WLD). The frequency of the remaining lesions such as thin soles or inter-digital hyperplasia will likely be too low for a separate analysis, but these lesions will be screened to ensure no difference exists between the treatment groups.To evaluate if a difference exists between the MODEL and NOMODEL treatment groups time to occurrence of lameness, first lesion and culling will be evaluated using survival analysis. This analysis will be done after all animals have been evaluated at 100-150 DIM for lesions in the hoof trimming chute. Animals without a lesion will be right censored at the time of evaluation. Time to occurrence of the first DD, SU or WLD lesion will be calculated from time of enrolment in the study. In addition, logistic regression will be used to evaluate the odds of lameness and lesions between treatment groups at the 100-150 DIM evaluation. Additional variables that will be considered for inclusion in all models will be age at enrolment, and milk production. Herd effects will be accounted for by using fixed effects and if the data includes repeated measures they will be accounted for by using an appropriate correlation matrix (Ian Robert Dohoo, 2009). A similar analysis will be done for the TRIM and NOTRIM group and for this analysis prior treatment group assignment will be included as a fixed effect.