Associations of Herd- and Cow-level Factors, Cow Lying and Standing Behavior, and Risk of Elevated Somatic Cell Count in Free-stall Housed Lactating Dairy Cows

摘要

Mastitis is the most economically significant disease impacting the global dairy industry (Seegers et al., 2003). Thus, understanding those management practices which reduce the incidence of mastitis is essential. Evidence suggests that encouraging cows to remain standing post-milking may reduce the risk of mastitis as there will be an increased likelihood of the teat canals being closed prior to the udder contacting the stall surface when a cow lies down, thus decreasing the odds of bacterial penetration of the teat (Tyler et al., 1997). The presence of feed around milking times encourages longer post-milking standing times (Tyler et al., 1997; DeVries and von Keyserlingk, 2005; DeVries et al., 2010). A study of tie-stall farms showed that when cows lay down for the first time 40 to 60 min after milking they tended to have decreased odds of acquiring a new environmental IMI compared to those cows which lay down sooner (DeVries et al., 2010). In that study the mean post-milking standing time of thecows was 79 min, which is much longer than that previously reported for free-stall housed cows (35 min: Tyler et al., 1997; 55 min: DeVries and von Keyserlingk, 2005). These averages indicate that in free-stall housing systems a large percentage of cows are lying down very quickly after milking. It is possible that these cows may have greater demands on standing time due to the time required to stand to access feed as well as increased standing times associated with milking.