title: Meta-analysis of the effects of sometribove zinc suspension on the production and health of lactating dairy cows.
abstract: OBJECTIVE
  To provide an updated evaluation of the efficacy and safety of sometribove zinc suspension (rbST-Zn), a form of recombinant bovine somatotropin, in lactating dairy cows.
  
  
  METHODS
  Meta-analysis.
  
  
  METHODS
  26 studies published in peer-reviewed journals or reviewed by a regulatory agency.
  
  
  METHODS
  To be included, a study had to involve the use of the rbST-Zn formulation available to US producers in accordance with the label instructions for treatment initiation (57 to 70 days postpartum), dose (500 mg, q 14 d), and route (SC).
  
  
  RESULTS
  For cows treated with rbST-Zn, mean milk, 3.5% fat-corrected milk, fat, and protein yields were increased by 4.00, 4.04, 0.144, and 0.137 kg/d (8.8, 8.89, 0.32, and 0.30 lb/d), respectively; however, the concentration of milk components did not change. Pregnancy proportion for the first 2 breeding cycles was increased by 5.4%, and pregnancy proportion for the duration of the trial was reduced by 5.5% for rbST-Zn-treated cows, compared with proportions for untreated cows. Mean body condition score (1 to 5 scale) was reduced by 0.06 points during the period of rbST-Zn use for treated cows. Administration of rbST-Zn had no effect on milk somatic cell count, the number of days to pregnancy, or inseminations per pregnancy; rates of fetal loss, twins, cystic ovaries, clinical lameness, lameness lesions, or traumatic lesions of the integumentary system; and odds of clinical mastitis or culling.
  
  
  CONCLUSIONS
  Results indicated that rbST-Zn administration to dairy cows effectively increases milk production with no adverse effects on cow health and well-being.
authors.affiliation: Department of Animal Science, College of Food Agricultural and Environmental Sciences, The Ohio State University, Columbus, OH 43210.
authors.forename: Normand R
authors.initials: NR
authors.lastname: St-Pierre
authors.forename: George A
authors.initials: GA
authors.lastname: Milliken
authors.forename: Dale E
authors.initials: DE
authors.lastname: Bauman
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Collier
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Hogan
authors.forename: Jan K
authors.initials: JK
authors.lastname: Shearer
authors.forename: K Larry
authors.initials: KL
authors.lastname: Smith
authors.forename: William W
authors.initials: WW
authors.lastname: Thatcher
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000139:chemically induced*; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D007774:Lactation / Q000187:drug effects*; D008892:Milk; D011994:Recombinant Proteins
chemical_list: D011994:Recombinant Proteins; D013006:Growth Hormone; C108583:sometribove