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Effects of supplementing a Saccharomyces cerevisiae fermentation product on the prevention and control of digital dermatitis in lactating dairy cows

      ABSTRACT

      Objective

      The aim of the study was to evaluate the effects of supplementing a Saccharomyces cerevisiae fermentation product (SCFP, NutriTek, Diamond V) on the prevention and control of digital dermatitis (DD) in lactating dairy cows.

      Materials and Methods

      A blinded randomized, controlled field study on a commercial robot-milking farm was performed for 5 mo using the first 2.5 mo for the base phase and the last 2.5 mo for the test phase. A total of 968 lactating cows were enrolled in the trial distributed over 4 pens. The SCFP and control supplements were fed in their respective partial mixed ration. GoPro (https://gopro.com) images of the cows’ hind feet in the milking robots were scored to identify the presence of DD using an M-stage DD classification system.

      Results and Discussion

      Pen-level analysis revealed no statistically significant differences in M-stage groups between the control and SCFP group during the base and test phases of the study. Cow level analysis indicated that the relative risk for having M2M2P lesions (ulcerated/active) versus having M0M4H lesions (healthy/contained) in the control group during the test phase was 1.8 times greater compared with the SCFP group. The transition from M0M4H to M2M2P lesions occurred more rapidly in the control group compared with the SCFP group.

      Implications and Applications

      The supplementation of SCFP warrants further research as a potential DD prevention and control strategy in dairy cattle.

      Key words

      INTRODUCTION

      Bovine digital dermatitis (DD) is a worldwide infectious disease causing lameness in the cattle industry (
      • Holzhauer M.
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      Herd- and cow-level prevalence of digital dermatitis in the Netherlands and associated risk factors..
      ;
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      • Phillips G.J.
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      Deep sequencing analysis reveals temporal microbiota changes associated with development of bovine digital dermatitis..
      ;
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      Prevalence of digital dermatitis in young stock in Alberta, Canada, using pen walks..
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      • Demirkan A.Ç.
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      • Altındiş M.
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      Isolation and identification of Treponema pedis and Treponema phagedenis-like organisms from bovine digital dermatitis lesions found in dairy cattle in Turkey..
      ;
      • Moreira T.F.
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      • Carvalho A.U.
      • Strube M.L.
      • Nielsen M.W.
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      Pathology and bacteria related to digital dermatitis in dairy cattle in all year round grazing system in Brazil..
      ;
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      • Zhang A.J.
      • van Schaik G.
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      Bovine digital dermatitis in Victoria, Australia..
      ;
      • Staton G.J.
      • Sullivan L.E.
      • Blowey R.W.
      • Carter S.D.
      • Evans N.J.
      Surveying bovine digital dermatitis and non-healing bovine foot lesions for the presence of Fusobacterium necrophorum, Porphyromonas endodontalis and Treponema pallidum..
      ). This incurable disease includes inflammation and skin damage characterized by circumscribed ulcerated and often proliferative lesions typically located on the plantar aspect of the hoof (
      • Blowey R.W.
      • Sharp M.W.
      Digital dermatitis in dairy cattle..
      ;
      • Read D.H.
      • Walker R.L.
      Papillomatous digital dermatitis (footwarts) in California dairy cattle: clinical and gross pathologic findings..
      ). Digital dermatitis has a wide range of severities and clinical stages resulting in chronically affected skin lesions (
      • Döpfer D.
      • Koopmans A.
      • Meijer F.A.
      • Szakáll I.
      • Schukken Y.H.
      • Klee W.
      • Bosma R.B.
      • Cornelisse J.L.
      • van Asten A.J.
      • ter Huurne A.A.
      Histological and bacteriological evaluation of digital dermatitis in cattle, with special reference to spirochaetes and Campylobacter faecalis..
      ;
      • Berry S.L.
      • Read D.H.
      • Famula T.R.
      • Mongini A.
      • Döpfer D.
      Long-term observations on the dynamics of bovine digital dermatitis lesions on a California dairy after topical treatment with lincomycin HCl..
      ). The inflammation caused by DD involves a strong infiltration of neutrophils and neutrophil chemotactic and antimicrobial factors (
      • Wilson-Welder J.H.
      • Alt D.P.
      • Nally J.E.
      Digital dermatitis in cattle: Current bacterial and immunological findings..
      ;
      • Watts K.M.
      • Fodor C.
      • Beninger C.
      • Lahiri P.
      • Arrazuria R.
      • De Buck J.
      • Knight C.G.
      • Orsel K.
      • Barkema H.W.
      • Cobo E.R.
      A differential innate immune response in active and chronic stages of bovine infectious digital dermatitis..
      ). Local inflammatory cells may contribute to the nonhealing course of the disease (
      • Wilson-Welder J.H.
      • Alt D.P.
      • Nally J.E.
      Digital dermatitis in cattle: Current bacterial and immunological findings..
      ;
      • Evans N.J.
      • Murray R.D.
      • Carter S.D.
      Bovine digital dermatitis: Current concepts from laboratory to farm..
      ). The consequences of DD are decreased animal welfare and economic loss due to reduced milk production, decreased reproductive performance, and premature culling (
      • Hernandez J.
      • Shearer J.K.
      • Webb D.W.
      Effect of lameness on the calving-to-conception interval in dairy cows..
      ;
      • Bruijnis M.R.N.
      • Hogeveen H.
      • Stassen E.N.
      Assessing economic consequences of foot disorders in dairy cattle using a dynamic stochastic simulation model..
      ,
      • Bruijnis M.R.N.
      • Beerda B.
      • Hogeveen H.
      • Stassen E.N.
      Assessing the welfare impact of foot disorders in dairy cattle by a modeling approach..
      ;
      • Relun A.
      • Lehebel A.
      • Chesnin A.
      • Guatteo R.
      • Bareille N.
      Association between digital dermatitis lesions and test-day milk yield of Holstein cows from 41 French dairy farms..
      ;
      • Gomez A.
      • Cook N.B.
      • Socha M.T.
      • Döpfer D.
      First-lactation performance in cows affected by digital dermatitis during the rearing period..
      ).
      Research has identified that DD is a multifactorial, polymicrobial disease with an essential bacterial component among which spirochetes, particularly treponemes, play a key role (
      • Rasmussen M.
      • Capion N.
      • Klitgaard K.
      • Rogdo T.
      • Fjeldaas T.
      • Boye M.
      • Jensen T.K.
      Bovine digital dermatitis: Possible pathogenic consortium consisting of Dichelobacter nodosus and multiple Treponema species..
      ;
      • Evans N.J.
      • Murray R.D.
      • Carter S.D.
      Bovine digital dermatitis: Current concepts from laboratory to farm..
      ;
      • Beninger C.
      • Naqvi S.A.
      • Naushad S.
      • Orsel K.
      • Luby C.
      • Derakhshani H.
      • Khafipour E.
      • De Buck J.
      Associations between digital dermatitis lesion grades in dairy cattle and the quantities of four Treponema species..
      ). The interaction of the causative and risk factors, which include the host, spirochetes, and an unhygienic environment, are thought to result in DD lesions and outbreaks of lameness. Topical treatment for DD generally focuses on the application of an antimicrobial (tetracycline or oxytetracycline) (
      • Shearer J.K.
      • Plummer P.J.
      • Schleining J.A.
      Perspectives on the treatment of claw lesions in cattle..
      ). Formalin and copper sulfate are routinely used as foot bath chemicals to help control DD; however, these agents are problematic to the environment and workers safety (
      • Salam D.
      • El-Fadel M.
      Mobility and availability of copper in agricultural soils irrigated from water treated with copper sulfate algaecide..
      ;
      • Doane M.
      • Sarenbo S.
      Exposure of farm laborers and dairy cattle to formaldehyde from footbath use at a dairy farm in New York State..
      ). Therefore, the search for alternative preventive measures to disinfectants and antibiotics is ongoing. Micronutrient supplementation including minerals, vitamins, amino acids, and fatty acids have been hypothesized to be beneficial for general bovine hoof hygiene and health (
      • Langova L.
      • Novotna I.
      • Nemcova P.
      • Machacek M.
      • Havlicek Z.
      • Zemanova M.
      • Chrast V.
      Impact of nutrients on the hoof health in cattle..
      ). Recently, there has been significant interest in the importance of micronutrient supplementation for hoof health and lameness. Studies have demonstrated that micronutrient supplementation of Zn, Cu, Mn, iodine, and biotin improved hoof health by enhancing the immune response and reducing the number and size of DD lesions (
      • Lean I.J.
      • Rabiee A.R.
      Effect of feeding biotin on milk production and hoof health in lactating dairy cows: A quantitative assessment..
      ;
      • Gomez A.
      • Bernardoni N.
      • Rieman J.
      • Dusick A.
      • Hartshorn R.
      • Read D.H.
      • Socha M.T.
      • Cook N.B.
      • Döpfer D.
      A randomized trial to evaluate the effect of a trace mineral premix on the incidence of active digital dermatitis lesions in cattle..
      ;
      • Zhao X.-J.
      • Li Z.-P.
      • Wang J.-H.
      • Xing X.-M.
      • Wang Z.-Y.
      • Wang L.
      • Wang Z.-H.
      Effects of chelated Zn/Cu/Mn on redox status, immune responses and hoof health in lactating Holstein cows..
      ).
      Saccharomyces cerevisiae fermentation products (SCFP) have been widely used in the dairy industry to enhance production performance and animal health (
      • Eastridge M.L.
      Major advances in applied dairy cattle nutrition..
      ;
      • Poppy G.D.
      • Rabiee A.R.
      • Lean I.J.
      • Sanchez W.K.
      • Dorton K.L.
      • Morley P.S.
      A meta-analysis of the effects of feeding yeast culture produced by anaerobic fermentation of Saccharomycescerevisiae on milk production of lactating dairy cows..
      ). Studies have indicated that SCFP are capable of enhancing immune capacity and reducing inflammatory responses (
      • Jensen G.S.
      • Patterson K.M.
      • Yoon I.
      Yeast culture has anti-inflammatory effects and specifically activates NK cells..
      ;
      • Knoblock C.E.
      • Shi W.
      • Yoon I.
      • Oba M.
      Effects of supplementing a Saccharomycescerevisiae fermentation product during the periparturient period on the immune response of dairy cows fed fresh diets differing in starch content..
      ). Because DD is characterized by destructive inflammation with neutrophil infiltration perpetuating lesion growth, we hypothesized that supplementation of SCFP may modulate the immune response to DD. The SCFP used in this study contains vitamins, antioxidants, β-glucan, and other yeast cell components and metabolites that have demonstrated immune modulating capabilities by initiating the innate and adaptive immune response through activation of immune cells and increasing leukocyte function (
      • Jensen G.S.
      • Patterson K.M.
      • Yoon I.
      Yeast culture has anti-inflammatory effects and specifically activates NK cells..
      ;
      • Volman J.J.
      • Ramakers J.D.
      • Plat J.
      Dietary modulation of immune function by β-glucans..
      ;
      • Al-Qaisi M.
      • Horst E.A.
      • Mayorga E.J.
      • Goetz B.M.
      • Abeyta M.A.
      • Yoon I.
      • Timms L.L.
      • Appuhamy J.A.
      • Baumgard L.H.
      Effects of a Saccharomyces cerevisiae fermentation product on heat-stressed dairy cows..
      ;
      • Mahmoud A.H.A.
      • Slate J.R.
      • Hong S.
      • Yoon I.
      • McGill J.L.
      Supplementing a Saccharomyces cerevisiae fermentation product modulates innate immune function and ameliorates bovine respiratory syncytial virus infection in neonatal calves..
      ;
      • Vailati-Riboni M.
      • Coleman D.N.
      • Lopreiato V.
      • Alharthi A.
      • Bucktrout R.E.
      • Abdel-Hamied E.
      • Martinez-Cortes I.
      • Liang Y.
      • Trevisi E.
      • Yoon I.
      • Loor J.J.
      Feeding a Saccharomyces cerevisiae fermentation product improves udder health and immune response to a Streptococcus uberis mastitis challenge in mid-lactation dairy cows..
      ). We hypothesized that supplementation with SCFP would reduce the prevalence of DD, and therefore, the study aimed to evaluate the effects of SCFP supplementation on the prevention and control of DD in lactating dairy cows.

      MATERIALS AND METHODS

      Animals, Diet, and Experimental Design

      All animal care and management procedures for the trial were approved by the University of Wisconsin-Madison Institutional Animal Care and Use Committee (A005122-R01-A02). The randomized controlled field study was conducted on a commercial dairy farm (Midwest, US) milking 3,000 Holstein cows using Astronaut A4 milking systems (Lely Inc.). Assuming an endemically affected herd, the sample size of 725 cows was calculated to detect a 50% disease reduction in acute DD lesions (M2), for an initial prevalence of 30% of DD cases at cow level in the control population, considering a 5% significance level and a statistical power of 80%. It was anticipated that approximately 33% of cows would be lost to follow-up during the project; therefore, 33% more cows were enrolled into the trial. A total of 968 lactating Holstein cows (15 primiparous and 953 multiparous, equally distributed among the control and SCFP groups) in early to mid lactation (average of 188 DIM, 120 SD) were enrolled in the trial distributed over 4 pens, 2 supplement and 2 control pens. Cows remained in the respective pens unless they were removed to be dried off and new cows could enter the pens after calving and be enrolled. All cows were housed in a freestall barn with sand-bedded stalls. The alleyways were scraped with an automated alley scraper system. Lame cows were identified by herdsmen during pen walks once per day. Cows exhibiting signs of lameness were separated and examined for the presence of DD lesions. Active DD lesions were treated using QuickHit Gel (SSI Corporation), a nonantibiotic chelated copper gel under a light wrap that was removed after 1 to 2 d. All cows underwent hoof trimming by a trained hoof trimmer at least once every 6 mo and went through a preventive footbath with 5% copper sulfate weekly.
      Investigators were blinded to the supplement and control groups. The SCFP supplement (NutriTek, Diamond V) was fed in the partial mixed ration (Table 1). The SCFP group was supplemented at 19 g of SCFP per cow daily for the entire duration of the trial. The trial was performed for 5 mo from June 20, 2018, to November 21, 2018. The first 2.5 mo were used as the base phase (adaptation to the supplement and baseline measurements) and the last 2.5 mo represented the test phase.
      Table 1Ingredient composition of the partial mixed ration
      Corn gluten pellet fed at the robotic milker.
      IngredientGroup
      ControlSCFP
      SCFP = Saccharomyces cerevisiae fermentation products.
      Ingredient, % of DM
       Corn silage shredlage45.045.0
       Alfalfa hay4.54.5
       Wet corn gluten feed14.614.6
       Ground shelled corn8.58.5
       Soybean meal7.67.6
       Canola meal3.13.1
       Soy hulls3.63.6
       Commercial AA
      Dairy Amino Shot (Synergy Feeds LLC).
      2.02.0
       Commercial premix
      Formulated to provide 1.1% Ca, 0.8% Na, 0.5% Mg, 1.7% K, 0.3% S, 68 mg/kg Zn, 61 mg/kg Mn, 17 mg/kg Cu, 213 mg/kg Fe, 0.5 mg/kg I, 0.3 mg/kg Co, and 0.5 mg/kg Se, 6,867 IU of vitamin A/kg, 1,717 IU of vitamin D3/kg, 58 IU of vitamin E/kg.
      4.94.9
       Control liquid molasses6.30.0
       SCFP liquid molasses0.06.3
      Formulated nutrient, % of DM
       CP16.316.3
       ADF19.619.6
       NDF31.531.5
       Ether extract3.63.6
       Starch21.621.6
       Sugars6.86.8
      1 Corn gluten pellet fed at the robotic milker.
      2 SCFP = Saccharomyces cerevisiae fermentation products.
      3 Dairy Amino Shot (Synergy Feeds LLC).
      4 Formulated to provide 1.1% Ca, 0.8% Na, 0.5% Mg, 1.7% K, 0.3% S, 68 mg/kg Zn, 61 mg/kg Mn, 17 mg/kg Cu, 213 mg/kg Fe, 0.5 mg/kg I, 0.3 mg/kg Co, and 0.5 mg/kg Se, 6,867 IU of vitamin A/kg, 1,717 IU of vitamin D3/kg, 58 IU of vitamin E/kg.

      Digital Dermatitis Image and Data Collection

      Investigators made 12 visits, 1 every 2 wk (so-called H-visit), to the farm to collect GoPro images of the cows’ hind feet in the milking robots to identify the presence of DD. The first H-visit was not included in the data set because image quality was insufficient for DD scoring due to poor lighting. The H2–H6-visits (5 H-visits) were used as the base phase, and H7–H12-visits (6 H-visits) were used as the test phase. Images of hind feet were taken with GoPro Hero 5 Black cameras (https://gopro.com). The cameras were mounted on wooden pedestals and placed in the back of the 12 robotic milkers (3 per pen) for 14 h (2 times 7 h each at 1300–2000 h and 0630–1330 h the following day; Figure 1). The lenses of the cameras were wiped clean using disposable paper towels at intervals of 30 min during the visits. Manure was removed from the robot standing surfaces using a water hose on the same occasions to improve visibility of feet and DD lesions. The time stamps of the JPG images (Figure 2) were merged with the time stamps of the back-up files from the robots to identify the cows on the images using ffmpeg (https://ffmpeg.org/download.html), Python 3.6 (Python Software Foundation), and R version 3.5.1 software (

      R Core Team. 2017. R: A language and environment for statistical computing. R Foundation for Statistical Computing.

      ). Back-up files from robots were generated using scripts from customized Lely International protocols transferred into Excel version 16.36 spreadsheets (Microsoft Corp.). The highest clarity images per cow were selected and evaluated by a trained investigator for the presence of DD and scored based on DD lesion type using the M-stage DD classification system described by
      • Döpfer D.
      • Koopmans A.
      • Meijer F.A.
      • Szakáll I.
      • Schukken Y.H.
      • Klee W.
      • Bosma R.B.
      • Cornelisse J.L.
      • van Asten A.J.
      • ter Huurne A.A.
      Histological and bacteriological evaluation of digital dermatitis in cattle, with special reference to spirochaetes and Campylobacter faecalis..
      and
      • Berry S.L.
      • Read D.H.
      • Famula T.R.
      • Mongini A.
      • Döpfer D.
      Long-term observations on the dynamics of bovine digital dermatitis lesions on a California dairy after topical treatment with lincomycin HCl..
      . M-stages were used together with signs of chronicity compiled into the following stages: M0 or M4H, M4P, M2, and M2P. Based on the M-stage DD classification system, cattle with normal digital skin being classified as M0; chronic lesions characterized by a thickened epithelium (hyperkeratosis) were classified as M4H; chronic lesions characterized by proliferative growth of the epithelium were classified as M4P; active ulcerative or granulomatous lesions ≥20 mm in diameter were classified as M2 lesions; and active ulcerative or granulomatous lesions with proliferative growth were classifieds a M2P (Figure 3). The letter H represents hyperkeratotic and the letter Prepresents the proliferative aspect of the lesion surfaces. The investigators had no means to discern which group of cows received which supplement before, during, or after the scoring of DD lesions.
      Figure 1
      Figure 1Setup for the wooden pedestal, light source, and extended battery pack for GoPro Hero 5 Black cameras (https://gopro.com) for image collection at cow foot level in the back of a milking robot. The white ovals depict the position of the camera setup in the milking robot.
      Figure 2
      Figure 2GoPro Hero 5 Black camera (https://gopro.com) image at cow foot level in the back of a milking robot.
      Figure 3
      Figure 3M-stages for the clinical stages of digital dermatitis (DD) used in this study: (A) hoof trimming chute view images and (B) robot view images. M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The letter H represents hyperkeratotic and the letter P represents the proliferative aspect of the lesion surfaces.
      Given the suboptimal hygiene status of the legs and feet of the cows, DD stages were likely to be underreported equally in the control and SCFP groups of cows. Because of the hygiene problems and difficulty of scoring the M-stages with smaller diameters, the decision was made to merge the scores of M0 and M4H stages and to contrast them to M4P and M2M2P classification scores.
      • Cernek P.
      • Bollig N.
      • Anklam K.
      • Döpfer D.
      Hot topic: Detecting digital dermatitis with computer vision..
      previously merged the M0 and M4H stages because the M0 and M4H lesions were unable to be distinguished with certainty. The most severe DD score per cow and visit was identified as DDMax using the following severity hierarchy of M-stages: M0 < M4H < M4P < M2 < M2P. If M2 lesions were detected by herdsmen in between H-visits, cows were topically treated and recorded in DairyCOMP 305 (VAS). A total of 49 individual lameness treatments for DD (base/test phase: 13/12 in the control group and 12/12 in the SCFP group) were recorded in DairyCOMP 305 during the study period and were used to adjust the M-stage score of the closest H-visit to time of treatment. No additional observations were created, only the M-stages were modified to M2 based on records of DD lameness treatments that were recorded closest to the respective visit date.

      Statistical Analysis

      Descriptive analysis of frequencies and proportions of observations was accomplished using histograms and frequency tables. Averages were calculated for numeric variables and tabulated. All statistical analysis was conducted using R version 3.5.1 software (

      R Core Team. 2017. R: A language and environment for statistical computing. R Foundation for Statistical Computing.

      ). Relative risks and their 95% confidence intervals were used for bivariate analysis to quantify associations between outcomes and exposure to potential risk factors (

      Dohoo, I., W. Martin, and H. Stryhn. 2009. Veterinary Epidemiologic Research. VER Inc.

      ).
      The regression models were fitted at the pen level as an unit of observation using the glmmPQL package in R. Logistic regressions for rates of DD lesions at the pen level for the base and test phase were weighted by the number of observations per H-visit, and pen was fitted as a random effect on the intercept. The regression equation used for the subset of data from the base and the test phase respectively was
      Proportion positive for M0M4H,M4MP,or M2M2P~groupMstage2+(1|pen)+error.
      [model equation 1]


      The variable definitions are as follows: group = control or SCFP group; Mstage2 = the lesions and signs of chronicity grouped as M0M4H, M4P, M2M2P; and pen = pen number.
      Cow level data analysis was the next step of evaluation. The outcome of the SCFP supplement group was compared with the control group at the cow level using the potential risk factors from equation 2, as described below. Multivariable logistic regression analysis associated with potential DD risk factors and interaction terms were used to correct for the presence of potential confounders. Because the models did not converge using CowID or pen number as random effects, repeated measures per cow were best corrected for using a fixed effect represented by the cow type variable assigned based on history of numbers of M2M2P lesions recorded per cow during the study period (
      • Gomez A.
      • Cook N.B.
      • Socha M.T.
      • Döpfer D.
      First-lactation performance in cows affected by digital dermatitis during the rearing period..
      ). An error level of α < 0.05 was used to declare statistical significance of effects. Backward stepwise elimination was used to transition from the full model equation in equation 2 to the final model (equation 3) listed in the results section. Backward step elimination was based on the P-value being greater than 0.05 for the association between predictor and outcome.
      group~intercept+Mstage2+Lact_cat+cDIMpd+cMilkpd+cow type+cMilkpd+cDIMpd+Mstage2phase+error.
      [model equation 2]


      The variable definitions are as follows: Mstage2 = the lesions and signs of chronicity grouped as M0M4H, M4P, M2M2P; Lact_cat = first-lactation heifers compared with 2+ lactation cows; cDIMpd = days in milk centered around the mean; cMilkpd = average daily milk production centered around the mean; cow type = assigned based on history of M2M2P lesions (type 1: no M2M2P lesion; type 2: single M2M2P lesion; type 3: multiple M2M2P lesions during study period); and phase = base or test phase of the trial. Milk yield per day and DIM were log-transformed to normalize their distributions and then centered around the mean. Centering around the mean was done by subtracting the mean milk yield or DIM from each milk yield or DIM value in the data set. The interaction terms of the model equation are cMilkpd × cDIMpd and Mstage2 × phase. Goodness of fit evaluation was accomplished using decreasing Akaike information criterion values during backward stepwise elimination.

      RESULTS AND DISCUSSION

      In this study, we explored the effect of SCFP supplementation on the prevention and control of DD in lactating dairy cows. We hypothesized that SCFP supplementation would reduce the prevalence of DD as compared with the control group.
      A total of 968 lactating cows were evaluated during 12 H-visits to a commercial dairy farm. The H1-visit, the first of 12 visits, was deleted from the data set because image quality was insufficient for DD scoring. This resulted in 6,920 observations analyzed for the trial. Table 2 lists the number of cow observations recorded at the group and pen level per H-visit, averaging 7.2 (3.2 SE) visits per cow. The trial used a novel approach for detecting and identifying DD lesions in lactating cows from a commercial robotic milking dairy by evaluating images from GoPro cameras attached to the milking robots (
      • Cernek P.
      • Bollig N.
      • Anklam K.
      • Döpfer D.
      Hot topic: Detecting digital dermatitis with computer vision..
      ). By using the GoPro images, we were able to efficiently evaluate approximately 600 cows per H-visit for DD lesions. Not all enrolled cows were evaluated during each H-visit because the recording of cows was dependent on whether cows entered the robot to be milked during the recording times per H-visit. Images generated by the cameras in the back of the milking robots showed both hind feet of the cow and each was scored for DD lesions at the cow level. This required a hierarchy of M-stages based on severity that assigned the most severe DD lesion among the 2 hind feet as the final cow record (
      • Gomez A.
      • Anklam K.S.
      • Cook N.B.
      • Rieman J.
      • Dunbar K.A.
      • Cooley K.E.
      • Socha M.T.
      • Döpfer D.
      Immune response against Treponema spp. and ELISA detection of digital dermatitis..
      ;
      • Kopke G.
      • Anklam K.
      • Kulow M.
      • Baker L.
      • Swalve H.H.
      • Lopes F.B.
      • Rosa G.J.M.
      • Dopfer D.
      The identification of gene ontologies and candidate genes for digital dermatitis in beef cattle from a genome-wide association study..
      ). The hierarchy of M-stages (M0 < M4H < M4P < M2 < M2P) was the result of ranking the diameter of the DD lesion in addition to the degree of ulceration and proliferation. The necessity for grouping of M0 and M4H lesions together resulted from poor leg hygiene reducing the visibility to identify M0M4H lesions at times, leading to the underestimation of M4H lesions. Although M4H lesions are not a sign for healthy skin, they are a sign for a contained or inactive DD stage compared with M2, M2P, and M4P lesions (
      • Zinicola M.
      • Lima F.
      • Lima S.
      • Machado V.
      • Gomez M.
      • Döpfer D.
      • Guard C.
      • Bicalho R.
      Altered microbiomes in bovine digital dermatitis lesions, and the gut as a pathogen reservoir..
      ). The suboptimal leg hygiene throughout the study’s duration was associated with the farm facility and herd management practices. Scoring lesions using images from the cameras was essential because the farm facility had no headgates to restrain the cows during scoring.
      Table 2Frequencies of cows evaluated supplemented with or without Saccharomyces cerevisiae fermentation products (SCFP
      SCFP: NutriTek (Diamond V).
      ) during the trial for each H-visit (1 visit every 2 wk), n = 6,920 observations
      Cows were evaluated during 12 biweekly H-visits for the trial. The H1-visit (data not shown), the first of 12 visits, was deleted from the data set because image quality was insufficient for digital dermatitis scoring.
      Group and penH2H3H4H5H6H7H8H9H10H11H12
      Control pen 1145164150151167165164154153151147
      Control pen 2131155162159152167161156154150147
      SCFP pen 3151155166165171171177162160158157
      SCFP pen 4134153160166167167166151157155146
      Total561627638641657670668623624614597
      1 SCFP: NutriTek (Diamond V).
      2 Cows were evaluated during 12 biweekly H-visits for the trial. The H1-visit (data not shown), the first of 12 visits, was deleted from the data set because image quality was insufficient for digital dermatitis scoring.

      Bivariate Analysis

      Table 3 displays the frequencies and relative percentages of aggregated M-stage lesions (Mstage2) during the base and test phases by intervention group at the pen and cow level. The base phase prevalence for M4P and M2M2P lesions in the control and SCFP groups was 24.0% and 26.6%, respectively. The prevalence for M4P and M2M2P lesions during test phase in the control and SCFP groups was 27.2% and 26.4%, respectively. The relative percentages of M4P lesions increased slightly from the base to the test phase in both the control and SCFP groups. The relative percentages of the M2M2P lesions in the SCFP group decreased considerably from the base phase (7.2%) to the test phase (2.8%), whereas the control group maintained above 5% for both the base (6.1%) and test (5.1%) phases. The associations were explored using relative risks initially. The relative risk for having M2M2P lesions versus having M0M4H lesions in the control group during the test phase was 1.8 (1.3–2.5 95% CI) times greater (P < 0.05) compared with the SCFP group. The statistical significance of these findings was further explored in detail and corrected for multiple other risk factors using the multivariable regression analysis.
      Table 3Frequencies and relative percentages of digital dermatitis (DD) lesions (Mstage2) in cows supplemented with or without Saccharomyces cerevisiae fermentation products (SCFP
      SCFP: NutriTek (Diamond V).
      ) during the base (first 2.5 mo of trial) and test (last 2.5 mo of trial) phases of the trial for each pen, n = 6,920 observations
      Mstage2
      Mstage2 = the DD lesions and signs of chronicity grouped as M0M4H, M4P, M2M2P. M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The letter H represents hyperkeratotic and the letter P represents the proliferative aspect of the lesion surfaces.
      Base phase control groupTest phase control group
      Pen 1Pen 2TotalPen 1Pen 2Total
      M0M4H5875801,1676617001,361
      (75.6%)(76.4%)(76.0%)(70.8%)(74.9%)(72.8%)
      M4P140135275225187412
      (18.0%)(17.8%)(17.9%)(24.1%)(20.0%)(22.0%)
      M2M2P504494484896
      (6.43%)(5.8%)(6.1%)(5.1%)(5.1%)(5.1%)
      Total7777591,5369349351,869
      (100%)(100%)(100%)(100%)(100%)(100%)
      Base phase SCFP groupTest phase SCFP group
      Pen 3Pen 4TotalPen 3Pen 4Total
      M0M4H5705961,1667097101,419
      (70.5%)(76.4%)(73.4%)(72.0%)(75.4%)(73.6%)
      M4P166142308245210455
      (20.6%)(18.2%)(19.4%)(24.9%)(22.3%)(23.6%)
      M2M2P7242114312253
      (8.9%)(5.4%)(7.2%)(3.2%)(2.3%)(2.8%)
      Total8087801,5889859421,927
      (100%)(100%)(100%)(100%)(100%)(100%)
      1 SCFP: NutriTek (Diamond V).
      2 Mstage2 = the DD lesions and signs of chronicity grouped as M0M4H, M4P, M2M2P. M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The letter H represents hyperkeratotic and the letter P represents the proliferative aspect of the lesion surfaces.

      Analysis at Pen Level

      Table 4 displays the base and test phase logistic regression analysis results for each M-stage group’s positive proportions as an outcome variable using the data shown in Table 3. Analysis results at the pen level revealed that there were no statistically significant differences in rates of positivity of the M-stage groups between the SCFP and control group during the base phase of the study (Table 4). This indicates that the SCFP and control groups started the study with similar levels of DD lesions.
      Table 4Logistic regression
      The base and test phase regressions are weighted by the number of observations per H-visit, and pen was fitted as a random effect on the intercept.
      of digital dermatitis (DD) lesions (Mstage2
      Mstage2 = the DD lesions and signs of chronicity grouped as M0M4H, M4P, M2M2P. M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The letter H represents hyperkeratotic and the letter P represents the proliferative aspect of the lesion surfaces.
      ) in cows supplemented with or without Saccharomyces cerevisiae fermentation products (SCFP
      SCFP: NutriTek (Diamond V).
      ) during the base (first 2.5 mo of trial) and test (last 2.5 mo of trial) phases of the trial at the pen level, nbase = 3,124 observations and ntest = 3,796 observations
      Variable
      The variable definitions are as follows: SCFP = the SCFP supplement group compared with the control group. Mstage2(M4P) = M4P lesions and signs of chronicity group (reference = M0M4H, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M2M2P) = M2M2P lesions and signs of chronicity group (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M4P):SCFP = the M4P lesions and signs of chronicity group for the base or test phase (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M2M2P):SCFP = the M2M2P lesions and signs of chronicity group for the base or test phase (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions).
      ValueSEt-valueP-valueOR
      Parameter estimates were transformed in odds ratios (OR) and 95% CI by exponentiation.
      2.50%
      Parameter estimates were transformed in odds ratios (OR) and 95% CI by exponentiation.
      97.50%
      Parameter estimates were transformed in odds ratios (OR) and 95% CI by exponentiation.
      Base phase
       (Intercept)1.150.1011.720.003.162.613.84
       SCFP−0.140.14−1.000.420.870.581.32
       Mstage2(M4P)−2.670.15−18.180.000.070.050.09
       Mstage2(M2M2P)−3.880.20−19.3380.000.020.010.03
       Mstage2(M4P):SCFP0.230.201.150.311.260.851.88
       Mstage2(M2M2P):SCFP0.310.271.120.331.360.792.32
      Test phase
       (Intercept)0.990.0812.270.002.682.143.35
       SCFP0.040.110.370.751.040.641.70
       Mstage2(M4P)−2.250.12−19.080.000.110.760.15
       Mstage2(M2M2P)−3.900.18−21.260.000.020.010.03
       Mstage2(M4P):SCFP−0.050.160.290.791.050.661.66
       Mstage2(M2M2P):SCFP−0.690.29−2.370.080.500.221.13
      1 The base and test phase regressions are weighted by the number of observations per H-visit, and pen was fitted as a random effect on the intercept.
      2 Mstage2 = the DD lesions and signs of chronicity grouped as M0M4H, M4P, M2M2P. M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The letter H represents hyperkeratotic and the letter P represents the proliferative aspect of the lesion surfaces.
      3 SCFP: NutriTek (Diamond V).
      4 The variable definitions are as follows: SCFP = the SCFP supplement group compared with the control group. Mstage2(M4P) = M4P lesions and signs of chronicity group (reference = M0M4H, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M2M2P) = M2M2P lesions and signs of chronicity group (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M4P):SCFP = the M4P lesions and signs of chronicity group for the base or test phase (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M2M2P):SCFP = the M2M2P lesions and signs of chronicity group for the base or test phase (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions).
      5 Parameter estimates were transformed in odds ratios (OR) and 95% CI by exponentiation.
      The pen level test phase logistic regression analysis indicates a reduced proportion of positive M2M2P lesions in the SCFP group compared with the control group (P = 0.08). The M2M2P lesions in the SCFP group had a lower rate according to the slope for transitioning from M0M4H to M2M2P compared with the control group indicated by an odds ratio of 0.5 (0.2–1.1 95% CI). In addition, the descriptive statistics for the test phase indicated that M2M2P lesions in the SCFP group (2.8%) were lower compared with the M2M2P lesions in the control group (5.1%) (Table 3). The main effect from the logistic regression using the pen level test phase data reveals a decreased proportion of positive M2M2P lesions in the SCFP group. The analysis also indicated that M4P lesions in the SCFP group (23.6%) were slightly increased compared with the M4P lesions in the control group (22.0%); however, the regression analysis did not result in a significant difference (P = 0.78) for this association (Table 4). The effects found during the test phase were attributed to the SCFP supplementation.

      Analysis at Cow Level

      Because the analysis at the pen level could be confounded by cow-level variables, such as milk production, DIM, and lactation number, an analysis at the cow level was conducted in addition to the pen-level analysis. For the purpose of cow-level analysis, the recurrence of active DD lesions (M2 or M2P) allows for cows to be assigned to cow types 1 (no M2M2P lesion), 2 (single M2M2P lesion), or 3 (multiple M2M2P lesions). Cow type frequencies by supplement group are shown in Table 5. The frequency tabulation for cow types per group did not reveal any obvious differences in frequencies. The statistical significance of associations was then further explored using multiple variable regressions.
      Table 5Cow type frequencies for cows supplemented with or without Saccharomyces cerevisiae fermentation products (SCFP
      SCFP: NutriTek (Diamond V).
      ), n = 6,920 observations
      GroupCow type
      Cow type was assigned to cows based on the reoccurrence of active digital dermatitis lesions (M2 or M2P). Cow type 1 = no M2M2P lesions during project duration; cow type 2 = single M2M2P lesion during project duration; and cow type 3 = multiple M2M2P lesions during project duration. M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The letter H represents hyperkeratotic and the letter P represents the proliferative aspect of the lesion surfaces.
      Type 1Type 2Type 3
      Control group2,531518356
      SCFP group2,606559350
      Total5,1371,077706
      1 SCFP: NutriTek (Diamond V).
      2 Cow type was assigned to cows based on the reoccurrence of active digital dermatitis lesions (M2 or M2P). Cow type 1 = no M2M2P lesions during project duration; cow type 2 = single M2M2P lesion during project duration; and cow type 3 = multiple M2M2P lesions during project duration. M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The letter H represents hyperkeratotic and the letter P represents the proliferative aspect of the lesion surfaces.

      Multiple Variable Analysis

      Multiple variable logistic regression analysis for potential DD risk factors and interaction terms associated with the SCFP supplement and control groups was performed to correct for the presence of potential confounders at the cow level associated with the outcome. Cow-level predictor variables include DIM, lactation number, and average weekly milk production. The average milk yield (kg/d) and DIM by phase and group, used as correction factors, are listed in Table 6. The model compared the control group with the SCFP group as the reference group. We were especially aware of the necessity for correcting for repeated measures by cow. Because the cow level regression models would not converge when fitted with random CowID or random pen effects, the cow type variable fitted as a fixed effect was the best alternative for correcting for repeated measures at the cow level. This type of correction for the repeated DD lesions per cow was used and reported by
      • Kulow M.
      • Merkatoris P.
      • Anklam K.S.
      • Rieman J.
      • Larson C.
      • Branine M.
      • Döpfer D.
      Evaluation of the prevalence of digital dermatitis and the effects on performance in beef feedlot cattle under organic trace mineral supplementation..
      . The Lact_cat variable from equation 1 fell out of the model during backward step elimination because it was not significantly associated with the outcome (P > 0.05). The final model equation for this logistic regression at the cow level was
      group~intercept+Mstage2+cDIMpd+cMilkpd+cow type+cMilkpdcDIMpd+Mstage2Phase+error.
      [model equation 3]


      Table 6Mean milk per day (kg) and mean DIM for cows supplemented with or without Saccharomyces cerevisiae fermentation products (SCFP
      SCFP: NutriTek (Diamond V).
      ) during the base (first 2.5 mo of trial) and test (last 2.5 mo of trial) phases of the trial, n = 6,920 observations
      PhaseGroupMean milk (kg/d)Mean DIM (d)
      BaseControl41.2192.9
      TestControl41.7195.0
      BaseSCFP42.5182.0
      TestSCFP42.4182.8
      1 SCFP: NutriTek (Diamond V).
      Table 7 displays the results of the multiple variable statistical analysis for associations between group, phase, milk yield, and DIM. The interaction term Mstage2(M2M2P):Phase(Test) was significant (P < 0.05) with an odds ratio of 2.2 (1.4–3.5 95% CI), indicating that during the test phase the cows in the control group developed M2 or M2P lesions 2.2 times faster compared with the cows in the SCFP group. This result was confirmed by the positive sign of the regression line slope from the interaction term shown in Table 7. This interpretation of the interaction term M-stage × phase is illustrated by the different regression line slopes separated by group in Figure 4. The regression line slopes indicate the rate of the transition from one lesion level to another in association with the outcome SCFP versus control group. The M2P lesions are highly infectious reservoirs of DD and preventing those lesions or even delaying them during the course of endemic DD represents an important gain in terms of time and resources to prevent further serious outbreaks of active lesions (
      • Gomez A.
      • Cook N.B.
      • Socha M.T.
      • Döpfer D.
      First-lactation performance in cows affected by digital dermatitis during the rearing period..
      ). The protective effect of the SCFP supplement may be due to the immune modulating effect of this product (
      • Jensen G.S.
      • Patterson K.M.
      • Yoon I.
      Yeast culture has anti-inflammatory effects and specifically activates NK cells..
      ;
      • Volman J.J.
      • Ramakers J.D.
      • Plat J.
      Dietary modulation of immune function by β-glucans..
      ), but this remains the subject of ongoing research. There was no significant association with either the SCFP or control groups for the cow type variable. The cow type variable was forced into the model to correct for repeated measures per cow.
      Table 7Multivariable logistic regression analysis for cows supplemented with or without Saccharomyces cerevisiae fermentation products (SCFP
      SCFP: NutriTek (Diamond V).
      ), n = 6,920 observations
      Variable
      The variable definitions are as follows: Mstage2(M4P) = M4P lesions and signs of chronicity group (reference = M0M4H, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M2M2P) = M2M2P lesions and signs of chronicity group (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). cDIMpd = days in milk centered around the mean. cMilkpd = average daily milk production centered around the mean. Cow type 2 = assigned to cows with a single M2M2P lesion during trial duration (reference = cow type 1; no M2M2P lesions during the duration of the trial). Cow type 3 = assigned to cows with multiple M2M2P lesions during trial duration (reference = cow type 1; assigned to cows no M2M2P lesions during the duration of the trial). Phase(Test) = test phase of the trial (reference = base phase of trial). Mstage2(M4P):Phase(Test) = the M4P lesions and signs of chronicity group for the test phase (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M2M2P):Phase(Test) = the M2M2P lesions and signs of chronicity group for the test phase (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). cMilkpd:Phase(Test) = average daily milk production centered around the mean for the test phase. M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The letter H represents hyperkeratotic and the letter P represents the proliferative aspect of the lesion surfaces.
      CoefficientSEz-valueP(>|z|)OR
      Parameter estimates were transformed in odds ratios (OR) and 95% CI by exponentiation.
      2.50%
      Parameter estimates were transformed in odds ratios (OR) and 95% CI by exponentiation.
      97.50%
      Parameter estimates were transformed in odds ratios (OR) and 95% CI by exponentiation.
      (Intercept)−0.000.04−0.030.981.000.921.09
      Mstage2(M4P)−0.090.10−0.920.360.920.761.10
      Mstage2(M2M2P)−0.180.16−1.100.270.840.621.15
      cDIMpd0.000.002.280.021.001.001.00
      cMilkpd−0.010.00−2.800.011.000.991.00
      Cow type 2
      The cow type variable was forced into the model to correct for repeated measures per cow.
      −0.060.07−0.830.410.940.821.08
      Cow type 3
      The cow type variable was forced into the model to correct for repeated measures per cow.
      0.040.090.380.701.040.861.24
      Phase(Test)−0.040.06−0.630.530.970.861.08
      Mstage2(M4P):Phase(Test)0.030.120.280.781.040.821.31
      Mstage2(M2M2P):Phase(Test)0.800.233.520.002.241.433.51
      cMilkpd:Phase(Test)0.000.001.440.151.001.001.01
      1 SCFP: NutriTek (Diamond V).
      2 The variable definitions are as follows: Mstage2(M4P) = M4P lesions and signs of chronicity group (reference = M0M4H, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M2M2P) = M2M2P lesions and signs of chronicity group (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). cDIMpd = days in milk centered around the mean. cMilkpd = average daily milk production centered around the mean. Cow type 2 = assigned to cows with a single M2M2P lesion during trial duration (reference = cow type 1; no M2M2P lesions during the duration of the trial). Cow type 3 = assigned to cows with multiple M2M2P lesions during trial duration (reference = cow type 1; assigned to cows no M2M2P lesions during the duration of the trial). Phase(Test) = test phase of the trial (reference = base phase of trial). Mstage2(M4P):Phase(Test) = the M4P lesions and signs of chronicity group for the test phase (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). Mstage2(M2M2P):Phase(Test) = the M2M2P lesions and signs of chronicity group for the test phase (reference = M0M4H group, where M0M4H are the M0 lesions combined with M4H lesions). cMilkpd:Phase(Test) = average daily milk production centered around the mean for the test phase. M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The letter H represents hyperkeratotic and the letter P represents the proliferative aspect of the lesion surfaces.
      3 Parameter estimates were transformed in odds ratios (OR) and 95% CI by exponentiation.
      4 The cow type variable was forced into the model to correct for repeated measures per cow.
      Figure 4
      Figure 4Effect plot for the interaction term Mstage2 × phase of the logistic regression model from (the digital dermatitis lesions and signs of chronicity grouped as M0M4H, M2M2P, M4P for the base and test phases). M0 = cattle with normal digital skin; M4H = chronic lesions characterized by a thickened epithelium (hyperkeratosis); M4P = chronic lesions characterized by proliferative growth of the epithelium; M2 = active ulcerative or granulomatous lesions ≥20 mm in diameter; M2P = active ulcerative or granulomatous lesions with proliferative growth. The effect plot illustrates the probability for having digital dermatitis lesions in the control group compared with the Saccharomyces cerevisiae fermentation product (SCFP) group. The interaction term Mstage2 (M2M2P) × phase (test) associated with the outcome of SCFP versus control group (circled in red) had an odds ratio of 2.2 (1.4–3.5 95% CI, P < 0.05). This indicates that during the test phase the control group cows had M2 or M2P lesions at a rate that was 2.2 times faster compared with the cows in the SCFP group. n = 6,920. The error bars represent the 95% CI for the point estimate for the probability.
      There was a slight odds ratio effect, 1.0 (1.000–1.001 95% CI), for the association between cDIMpd and the outcomes, whereas cows in the control group were more often (P < 0.02) above average DIM. As DIM increases above average, the development of M2 and M2P lesions is significantly faster in the control group compared with the SCFP group (P < 0.05). These are estimates of the direct effect of the potential confounder DIM on the outcome, not the total effect of DIM on the outcome variable. We infer from the results that during later lactation cows benefited from the SCFP intervention. This is an interesting finding because later DIM imply longer exposure to the infectious pressure of DD. Being protected from DD more efficiently during later lactation, particularly as cows mature, is an advantage for longevity and well-being in addition to a beneficial preparation for entering the dry cow period and the next lactation. Because DIM represents the passage of time, implying that cows later in their lactation are being affected and exposed to DD for a longer duration, the significant rapid increase of M2 and M2P lesions in the control group compared with the SCFP group suggests that SCFP supplementation has the potential to delay major outbreaks of DD.
      The suboptimal leg hygiene was a limitation of the study leading to possible underreporting of minor lesions such as M4H. Therefore, we joined the M0 and M4H stages. The study design likely led to low statistical power for data analysis at the pen level; however, this could not be altered.

      APPLICATIONS

      The DD prevalence at the pen level as measured as M2 or M4 stages of DD was not significantly altered by the SCFP supplementation in lactating cows during the current study. However, at the cow level, the SCFP supplementation revealed an odds ratio for having M2M2P lesions was roughly 2 times lower, and the rate for progression of M0M4H into M2M2P lesions was significantly reduced compared with the control supplementation. Enhanced protection from DD is advantageous to the longevity, performance, and well-being of cattle. Further research is warranted to determine if the cow level effect of SCFP supplementation on DD reduction could be enhanced by supplement level or earlier timing of supplementation during the cow’s life, such as before the first calving.

      ACKNOWLEDGMENTS

      The authors gratefully acknowledge the producers for their support with this study and Diamond V Inc. (Cedar Rapids, IA) for funding this trial.

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