title: Use of a stair-step compensatory gain nutritional regimen to program the onset of puberty in beef heifers.
abstract: It was hypothesized that metabolic programming of processes underlying puberty can be shifted temporally through the use of a stair-step compensatory growth model such that puberty is optimally timed to occur at 11 to 12 mo of age. Forty crossbred beef heifers were weaned at approximately 3.5 mo of age and, after a 2-wk acclimation period, were assigned randomly to 1 of 4 nutritional groups: 1) low control (LC), restricted feed intake of a forage-based diet to promote BW gain of 0.5 kg/d until 14 mo of age, 2) high control (HC), controlled feed intake of a high-concentrate diet to promote BW gain of 1 kg/d until 14 mo of age, 3) stair-step 1 (SS-1), ad libitum feed intake of a high-concentrate diet until 6.5 mo of age followed by restricted access to a high-forage diet to promote BW gain of 0.35 kg/d until 9 mo of age, ad libitum feed intake of a high-concentrate diet until 11.5 mo of age, and restricted intake of a high-forage diet to promote BW gain of 0.35 kg/d until 14 mo of age, and 4) stair-step 2 (SS-2), reverse sequence of SS-1, beginning with restricted access to a high-forage diet. Body weight (every 2 wk) and circulating concentrations of leptin (monthly) were determined throughout the experiment. Concentrations of progesterone in blood samples collected twice weekly beginning at 8 mo of age were used to determine pubertal status. Body weight gain followed a pattern similar to that proposed in our experimental design. Circulating concentrations of leptin increased following distinct elevations in BW but decreased abruptly after feed intake restriction. Survival analysis indicated that the percentage of pubertal heifers in the LC group was lower (P < 0.05) than all other groups throughout the experiment. Although heifers in SS-1 were nutritionally restricted between 6.5 and 9 mo of age, the proportion pubertal by 12 mo of age did not differ (P = 0.36) from that of the HC group, with 80% and 70% pubertal in SS-1 and HC, respectively. In contrast, the proportion of heifers pubertal by 12 mo of age in the SS-2 group (40%) was lower (P < 0.05) than both HC and SS-1. However, by 14 mo of age, 90% of heifers in the SS-2 group had also attained puberty compared to only 40% of the LC group. In summary, these data provide evidence that changes in the nutritional and metabolic status during the early juvenile period can program the onset of puberty that occurs months later, allowing optimal timing of sexual maturation in replacement beef heifers.
authors.affiliation: Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102 Department of Animal Science, Texas A&M University, College Station 77843.
authors.forename: R C
authors.initials: RC
authors.lastname: Cardoso
authors.affiliation: Department of Animal Science, Texas A&M University, College Station 77843.
authors.forename: B R C
authors.initials: BR
authors.lastname: Alves
authors.affiliation: Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102 Department of Animal Science, Texas A&M University, College Station 77843.
authors.forename: L D
authors.initials: LD
authors.lastname: Prezotto
authors.affiliation: Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102 Department of Animal Science, Texas A&M University, College Station 77843.
authors.forename: J F
authors.initials: JF
authors.lastname: Thorson
authors.affiliation: Department of Animal Science, Texas A&M University, College Station 77843.
authors.forename: L O
authors.initials: LO
authors.lastname: Tedeschi
authors.affiliation: Division of Animal Sciences, University of Missouri, Columbia 65211.
authors.forename: D H
authors.initials: DH
authors.lastname: Keisler
authors.affiliation: Department of Animal Sciences, North Dakota State University, Fargo 58108.
authors.forename: C S
authors.initials: CS
authors.lastname: Park
authors.affiliation: Department of Animal Science, Texas A&M University, College Station 77843.
authors.forename: M
authors.initials: M
authors.lastname: Amstalden
authors.affiliation: Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102 Department of Animal Science, Texas A&M University, College Station 77843 glwilliams@tamu.edu.
authors.forename: G L
authors.initials: GL
authors.lastname: Williams
mesh_terms: D000367:Age Factors; D000821:Animal Feed; D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D002417:Cattle / Q000254:growth & development* / Q000502:physiology; D004032:Diet / Q000662:veterinary; D004435:Eating / Q000502:physiology; D005260:Female; D020738:Leptin / Q000097:blood; D009747:Nutritional Physiological Phenomena / Q000502:physiology*; D012741:Sexual Maturation / Q000502:physiology*; D015430:Weight Gain / Q000502:physiology
chemical_list: D020738:Leptin
keywords: beef heifers; compensatory gain; leptin; nutritional programming; puberty