Abstract
The paper was designed to assess the influence of Mycobacterium avium subsp. paratuberculosis (MAP) infection status of cows at culling (antibody positive vs negative) on carcass traits: weight and conformation and fat cover scores. A generalized least squares linear model was used to assess the influence of MAP on weight. Subsequently, a random effects logistic regression was completed in order to model the relation between MAP and conformation score (fair vs poor carcasses). A random effects ordered logistic model was used to estimate the influence on fat cover. The results indicated that seropositives had carcass weights 58.45 (34.65-83.35) kg lower than seronegatives. Regarding conformation score, the odds of having poor conformation instead of fair was 3.85 (1.35-11.85) times higher in seropositives. The odds of seropositives achieving a higher fat cover was approximately 5 (1.41-9.09) times lower than the odds for seronegatives. The estimated effects could be useful when assessing the economic benefits of a paratuberculosis control program.
Highlights
Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of paratuberculosis Johne’s disease (JD), a chronic granulomatous enteric disease of domestic and wild ruminants
The paper was designed to assess the influence of Mycobacterium avium subsp. paratuberculosis (MAP) infection status of cows at culling on carcass traits: weight and conformation and fat cover scores
The main signs include progressive weight loss and chronic watery diarrhea in the most advanced stages; MAP bacteria slowly damage the intestines of infected animals and signs get worse with time because the digestive tissue becomes increasingly injured
Summary
Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of paratuberculosis Johne’s disease (JD), a chronic granulomatous enteric disease of domestic and wild ruminants. JD causes serious economic losses in dairy farming, mainly as a result of reduced milk production (Kudalh et al, 2004; Beaudeau et al, 2007; Aly et al, 2010), increased susceptibility to other diseases, especially mammary infections (Tiwari et al, 2005; Villarino & Jordan, 2005), loss of body weight (Johnson-Ifearulundu et al, 2001), and consequential premature culling and increased replacement costs. The main signs include progressive weight loss and chronic watery diarrhea in the most advanced stages; MAP bacteria slowly damage the intestines of infected animals and signs get worse with time because the digestive tissue becomes increasingly injured. Enteritis causes malabsorption of protein and essential nutrients across the intestinal epithelium and in the later stages results in net protein loss
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