title: Characteristics and management practices associated with milk production in dairy herds in Ohio enrolled in official Dairy Herd Improvement Association programs.
abstract: OBJECTIVE
  To determine herd characteristics and management practices associated with milk production in dairy herds enrolled in official Dairy Herd Improvement Association (DHIA) programs in Ohio.
  
  
  METHODS
  186 dairy farms in Ohio.
  
  
  METHODS
  All herds in official DHIA programs in 9 counties were invited to participate. Information regarding herd characteristics and management practices was obtained, using a standardized questionnaire. Bulk-tank milk samples were obtained for bacteriologic culture. Official DHIA test-day records were obtained, and associations were identified, using multivariable ANOVA procedures.
  
  
  RESULTS
  Of 479 eligible producers, 186 (39%) participated, and consecutive bulk-tank milk samples were available for culture from 172 (36%). Streptococcus agalactiae and Mycoplasma spp were not recovered from bulk-tank milk samples, but Staphylococcus aureus was recovered from 64 (37%) herds. Mean (+/- SD) number of lactating cows in participating herds was 97+/-66, with 123 (66%) herds milking < 100 cows. The RHA was significantly associated with number of cows in milk, estimated percentage of herd detected in estrus, reported annual percentage of heifer calves born alive that died before 8 weeks old, percentage days in milk, use of bovine somatotropin during the preceding 2 years, and sex of the person completing the questionnaire.
  
  
  CONCLUSIONS
  In this study, the strongest indicator of milk production was number of cows in milk. However, merely adding cows to a herd should not be considered to guarantee increased milk production, because other management traits could be confounded with increased number of cows in a herd.
authors.affiliation: Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus 43210-1092, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Khaitsa
authors.forename: T E
authors.initials: TE
authors.lastname: Wittum
authors.forename: K L
authors.initials: KL
authors.lastname: Smith
authors.forename: J L
authors.initials: JL
authors.lastname: Henderson
authors.forename: K H
authors.initials: KH
authors.lastname: Hoblet
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D002417:Cattle / Q000502:physiology*; D003612:Dairying / Q000379:methods*; D005260:Female; D006801:Humans; D007774:Lactation; D008892:Milk / Q000378:metabolism* / Q000382:microbiology; D009820:Ohio; D013211:Staphylococcus aureus / Q000302:isolation & purification; D011795:Surveys and Questionnaires