Effect of Mycobacterium XXXX on production, reproduction, and health traits in US Holsteins.

@entity281 @entity291 @entity3068
Our objective was to estimate the effect of Mycobacterium @entity281 on milk, fat, and protein yield deviations, pregnancy rate, lactation somatic cell score, and projected total months in milk (productive life). A serum ELISA and fecal culture for M. @entity3068 were performed on 4375 Holsteins in 232 DHIA herds throughout the US. Primarily first through third lactation @entity291 (99% of total) were assayed for @entity281 . Trait information (except productive life) was obtained for the lactation concurrent with disease tests. Productive life was total months in milk through a @entity291 's life, which was projected if a @entity291 was still milking. For most analyses, case definition for M. @entity281 was defined as either an ELISA S/P ratio>or=0.25 or a positive fecal culture for M. @entity3068 or both. To determine if diagnostic test affected estimates, case definition was redefined to include only @entity291 with ELISA S/P ratios>or=0.25 or only fecal culture-positive @entity291 . Linear models were used to estimate effect of M. @entity281 on traits. M. @entity281 @entity291 (7.89% of @entity291 ) produced 303.9 kg less milk/lactation, 11.46 kg less fat/lactation, and 9.49 kg less protein/lactation (P<or=0.003). Infected @entity291 had higher pregnancy rates (1.39%) (P=0.0385) and lower productive life (2.85 months) (P<or=0.0001). M. @entity281 did not affect somatic cell score. Effect of @entity281 on milk and protein yields was larger in first lactation M. @entity3068 -positive @entity291 relative to @entity291 that tested positive in later lactations. Fecal culture-positive @entity291 had consistently larger effects on all traits than ELISA-positive @entity291 . M. @entity281 , and not just clinical @entity3068 , decreases milk, fat, and protein yields, thus increasing the estimated cost of @entity3068 to the US dairy industry.
