Association of Mycobacterium avium subspecies paratuberculosis infection with milk production and calving interval in Iranian Holsteins |
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Authors: | Ansari-Lari Maryam Haghkhah Masoud Mahmoodi Fereshteh |
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Institution: | (1) Department of Food Hygiene and Public Health, Shiraz University, Shiraz, 71345, Iran;(2) Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, 71345, Iran |
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Abstract: | There are inconsistent results for the association of Mycobacterium avium subspecies paratuberculosis (MAP) infection with production and reproduction in dairy cows. Determination of these associations in each region is essential
to encourage participation of dairy cattle producers in disease control programs. This study was conducted in Shiraz, southern
Iran, to quantify the association of subclinical MAP infection with 305-day milk production and calving interval in Iranian
Holsteins. A total of 21 dairy herds were selected for the study and in each herd, quarter milk samples were collected from
ten to 12 dairy cows for PCR analysis. Data about parity, calving interval, length of lactation period, total milk production
and 305-day milk production were also provided for each animal. Overall, 252 individual milk samples were collected. Herd-
and individual-level prevalence of MAP infection were 23.8% (95% CI, 6.2–41.4%) and 3.2% (95% CI, 1.3–5.1%), respectively
based on IS900 nested PCR. The results for 305-day milk production revealed a 248 kg reduction in positive cows compared with
negative ones (P = 0.009). When cows from positive herds were compared with cows from negative herds, a 335-kg reduction in 305-day milk production
(P = 0.005) and a 30-day increase in calving interval (P = 0.057) were observed in the former group. These findings support the previous results that paratuberculosis infection is
negatively associated with the performance of the animals. |
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