Management Practices and Reported Antimicrobial Usage on Conventional and Organic Dairy Farms

Abstract

The primary objective was to compare reported antimicrobial usage between conventional and organic dairy farms. A secondary objective was to contrast selected management characteristics of conventional and organic dairy herds. A questionnaire was administered on site to selected dairy farmers located in Michigan, Minnesota, New York, and Wisconsin. Organic herds (n = 32) were smaller and produced less milk than conventional herds (n = 99). Lactating cows in organic dairies were more likely to be housed in tie stalls, whereas most conventional dairies housed cows in free stalls and milked in a parlor. Total mixed rations and purchased feeds were used on more conventional dairy farms compared with organic dairy farms. Conventional dairy producers were more likely to use advice from veterinarians for recommendations of treatment, and organic dairy producers were more likely to rely on advice from other farmers. Based on recall of antibiotic usage in the previous 60 d, 5.1, 84.9, 9.1, and 0.9% of farmers with conventional herds reported treatment of none, 1 to 10%, 11 to 25%, and >25% of milk cows, respectively. Most organic farmers (90.6%) reported no antibiotic treatments of milk cows, whereas 9.4% reported treating 1 to 10% of milk cows. Ceftiofur was the most commonly reported antibiotic for both farm types. Milk replacer containing antibiotics was reportedly used on 49.5% of conventional herds but only on one organic herd (3.1%). Antibiotics were used in heifer calves on 74.7% of conventional herds versus 21.9% of organic herds. Antibiotics to treat mastitis were used on 79.8% of conventional herds but on none of the organic herds. Most organic farms were in compliance with standards in advance of implementation of regulations.

The environmental impact of recombinant bovine somatotropin (rbST) use in dairy production

“…Annual milk yields are significantly decreased under organic management, and we used a value 20% lower than that of conventional systems, based on reported reductions in yield ranging from 14.3% to 26.2% (43,44,67,68). Because of a paucity of available data, the proportion of heifers and dry cow equivalents within the herd was assumed to be equal to those reported for conventional production.…”

Management Practices and Their Potential Influence on Johne’s Disease Transmission on Canadian Organic Dairy Farms—A Conceptual Analysis

“…The presence of deer on the farm has been associated with increased odds of being JD positive [79]. However, according to a study by Zwald et al [67], there is no difference in farmer reported contact rates with other farmed or wild animals between conventional and organic dairy farms. Nevertheless, it remains unclear how well rabbits or deer can be kept off the pastures at any time during the year.…”

“…While there are many other reasons why producers convert to organic farming, some smaller farms might see an opportunity to avoid the consolidation process and increase farm income by converting to organic milk production. More recent reports demonstrate that organic farms tend to be smaller than conventional farms [7,8,67,68] (Figure 2). Small farms have been shown to have decreased odds of being JD positive [30,38] and, thus, smaller organic farms might have a reduced JD herd level prevalence compared to larger conventional farms.…”

“…Similarly, Zwald et al [67] stated that JD was more commonly reported by producers on conventional than organic dairies based on a management questionnaire of a sample of farms from Michigan, Minnesota, New York, and Wisconsin, USA. However, the conventional herds were larger than the organic herds in this study.…”

“…Zwald et al [67] and Kijlstra [64] reported that organic farms use surface water more frequently than conventional farms as drinking water for livestock. This might pose the risk of spread of diseases that are transmitted by organisms that survive in the water or in the moisture around the water accesses, such as internal parasites (e.g., liver fluke).…”