title: Consumption of ground beef obtained from cattle that had received steroidal growth promotants does not trigger early onset of estrus in prepubertal pigs.
abstract: BACKGROUND
  The earlier onset of puberty seen in young American girls has led researchers to question if a causal relation exists between dietary sources of estrogenic compounds and precocious puberty.
  
  
  OBJECTIVE
  Using the prepubertal gilt (young female pig) as an animal model, our hypothesis is that feeding beef obtained from cattle receiving growth-promoting steroidal implants postweaning does not alter the onset of puberty or the peripubertal body composition of gilts compared with contemporaries fed nonimplanted "natural" beef or a common meat alternative, tofu.
  
  
  METHODS
  The base diet was formulated using canola meal replacing soybean meal to reduce diet estrogenicity. Feed intake was monitored and controlled to ensure similar intake. Gilts were assigned to treatments based on dam and initial body weight (mean: 24.5 ± 3.20 kg) at 61 d of age. The negative control base diet was supplemented with daily feedings of a cooked patty from nonimplanted steers (natural), from steers that had been treated with growth promotants [100 mg trenbolone acetate and 14 mg estradiol (E2) benzoate; implanted], or cooked tofu patty.
  
  
  RESULTS
  E2 equivalents (nanogram per kilogram, as fed as analyzed by E-Screen) of the tofu (a soy-based product) supplement were ∼570 times the natural and ∼170 times the implanted supplements. There were no observed differences across treatments in live weight gain (P = 0.90), longissimus muscle area developed at the 10th and 11th rib interface (P = 0.46), and subcutaneous fat deposition (P = 0.41) at the same location over time or in the number of days to reach estrus (P = 0.55).
  
  
  CONCLUSIONS
  Consumption of beef from growth implanted or natural steers or tofu at levels similar to those typically consumed by humans did not impact growth or onset of estrus in these prepubertal gilts.
authors.affiliation: Department of Animal Sciences, North Dakota State University, Fargo, ND;
authors.forename: James D
authors.initials: JD
authors.lastname: Magolski
authors.affiliation: USDA, Agricultural Research Service, Biosciences Research Laboratory, Fargo, ND.
authors.forename: Nancy W
authors.initials: NW
authors.lastname: Shappell
authors.affiliation: Department of Animal Sciences, North Dakota State University, Fargo, ND;
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Vonnahme
authors.affiliation: Department of Animal Sciences, North Dakota State University, Fargo, ND;
authors.forename: Giovana M
authors.initials: GM
authors.lastname: Anderson
authors.affiliation: Department of Animal Sciences, North Dakota State University, Fargo, ND;
authors.forename: David J
authors.initials: DJ
authors.lastname: Newman
authors.affiliation: Department of Animal Sciences, North Dakota State University, Fargo, ND; eric.p.berg@ndsu.edu.
authors.forename: Eric P
authors.initials: EP
authors.lastname: Berg
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002417:Cattle; D004958:Estradiol / Q000737:chemistry / Q000494:pharmacology*; D004971:Estrus / Q000187:drug effects*; D005260:Female; D005504:Food Analysis; D008297:Male; D008460:Meat / Q000032:analysis*; D012741:Sexual Maturation / Q000187:drug effects*; D045730:Soy Foods / Q000032:analysis; D013552:Swine / Q000502:physiology*; D014204:Trenbolone Acetate / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D004958:Estradiol; D014204:Trenbolone Acetate