RESUMO
Automatic Milking System (AMS) installations are increasing in the USA despite the higher investment cost than conventional systems. Surveys on AMSs conducted outside the USA focused on small-medium herds, specific regions, or aspects of AMS milking. This study described farmers' perceptions about the decision-making process of adopting an AMS in the USA's large dairies (≥7 AMS boxes) regarding changes in technology, housing, management practices, labor, herd performance, and health. After being contacted, 27 of 55 farmers from large AMS herds completed the survey. The main reasons for adopting an AMS were labor costs, cows' welfare, and herd performance. Most farms constructed new barns, used a free-flow traffic system, and changed their feed management. Increases in water and energy use were perceived by 42% and 62% of farmers, respectively. Farmers estimated decreases in labor costs of over 21%, and AMS employees worked 40-60 h/week. Milk production increases were reported by 58%, with 32% observing higher milk fat and protein content. Easier sick cow detection, better mastitis management, and improvements in pregnancy rates were reported. Thus, farmers transitioning to AMSs perceived altered resource utilization, labor cost savings, and improvements in employee quality of life, animal welfare, and farm management. While 54% of respondents would recommend an AMS to other farms, 38% suggested considering additional aspects prior to adoption.
RESUMO
Dry-off, and the period around parturition, are associated with increased susceptibility to intramammary infections in dairy cows. The immunological profiles of mammary gland secretions during these periods are not well described. The objective of the present study was to better characterize association(s) between chronic subclinical Environmental Streptococci infections at dry-off and relative levels of mRNA transcripts encoding multiple immunologic mediators present in cells derived from mammary gland secretions at dry-off and continuing through parturition. The chronic subclinical bacterial infections in the present study were characterized by multiple isolations of Streptococcus species and elevated SSC for a minimum of three weeks prior to dry-off. The majority of differences between principal and control quarters were identified at dry-off. Transcript levels of IL-17, IL2Rα and iNOS were increased while pro-inflammatory cytokine IL-6, and the regulatory cytokine IL-10, were reduced. Following antibiotic treatment of mammary glands, IL-17 transcripts remained elevated over the course of the study, indicative of a persistent insult. IL-4 transcript levels were modestly elevated at 7 days following dry-off and significantly elevated at 14 days, consistent with activated T(H)1 and T(H)2 lymphocytes in the principal quarters, respectively. From a temporal perspective, transcript levels of IL-8 decreased in all animals through the dry-off period animals and returned to pre-dry-off levels at parturition; levels of iNOS peaked at parturition. Five of the six principal cows experienced recurrent bacterial mastitis during the subsequent lactation; four were in the same quarter as was initially infected with Streptococcus and three of these four were due to coliforms. Taken together, this apparent chronic susceptibility of select mammary glands to bacterial infection would suggest a physiologic and/or immunologic dysfunction. Identification of factor(s) that contribute to the predisposition of mammary glands to developing mastitis should facilitate development of new control strategies.
