Effects of pre- and postnatal testosterone treatments on growth and carcass traits of heifers used in a single-calf heifer system

Reiling, Bryan Alan

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https://hdl.handle.net/2142/19981 Copy

Description

Title

Effects of pre- and postnatal testosterone treatments on growth and carcass traits of heifers used in a single-calf heifer system

Author(s)

Reiling, Bryan Alan

Issue Date

1996

Doctoral Committee Chair(s)

Berger, Larry L.

Department of Study

Animal Sciences

Discipline

Animal Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Biology, Animal Physiology
• Agriculture, Animal Culture and Nutrition

Language

eng

Abstract

Three studies evaluated growth and carcass traits of heifers in a single-calf heifer system. In Study 1, 24 prenatally androgenized (PA) heifers and 27 control (C) heifers were fed a finishing diet postpartum and slaughtered at 1.1 cm s.c. fat. Calves were weaned at 117 d of age. Preweaning, PA heifers gained 22.5% faster $(P<.01)$ and were 17.3% more efficient $(P<.01)$ than C heifers. Calf gain was not affected. The PA and C pairs gained 2.88 and 2.53 kg/d, respectively, and efficiency improved $(P<.01)$ 10.8%. Pre- and postweaning, PA heifers gained 23% faster $(P<.01)$ and were 16% more efficient $(P<.02)$ than C heifers. At slaughter, PA and C heifers averaged 853 and 865 d of age, respectively. Skeletal (B$\sp0)$ and lean (A$\sp{60})$ maturity scores were similar between treatments. One carcass was C-maturity. Marbling scores exceeded Small$\sp{50},$ and sensory traits were similar. In Exp. 1 of Study 2, 33 yearling (16 C and 17 PA) and 39 once-calved (20 C and 19 PA) heifers were used to evaluate effects of age and PA. Once-calved heifers gained 11% faster $(P<.08),$ but had similar $(P=.44)$ gain to feed ratios (.138 vs..131) as yearlings. Growth was not affected by PA. Yearling and once-calved heifers averaged 707 and 1080 d of age, respectively, at slaughter. Despite maturity differences $(P<.01),$ marbling scores $(P=.26)$ and percentage of choice carcasses $(P = .27)$ were similar. Organoleptic properties did not differ. Experiments 2 and 3 evaluated the effect of melengestrol acetate (MGA) and Synovex-H on feedlot traits of once-calved heifers. In Exp. 2, 48 once-calved Simmental cross heifers were fed to possess.8 cm s.c. fat. In Exp. 3, 52 moderately sized heifers were fed for 116 d. Performance in Exp. 2 was not affected by MGA, but heifers fed MGA in Exp. 3 gained 9% faster $(P<.05)$ than C heifers. In Exp. 2, Synovex-H improved ADG $(P<.09)$ and feed efficiency $(P<.07),$ but did not affect performance in Exp. 3. Carcass traits were not affected. In Study 3, 12 C and 12 PA L and five (2 C and 3 PA) nonlactating (NL) heifers were used to assess effects of PA and L on metabolic activity of s.c. adipose tissue (AT). The NL heifers gained.22 kg/d (13.9%) faster $(P=.20)$ than L heifers and had greater fat deposition, and PA heifers were fatter but gained 14.6% faster than C heifers, preweaning. Calves were weaned at 112 $\pm$ 1 d of age, and AT was biopsied at 77 and 126 d postpartum. Epinephrine (E) and norepinephrine (NE) increased in vitro fatty acid (IVFA) release 25 $(P<.01)$ and 15% $(P<.06),$ respectively. Near-maximal lipolytic release of IVFA as estimated by E with theophylline and adenosine deaminase (ETAD) stimulation was 73% greater $(P<.01)$ than basal rates. Basal IVFA release was not affected by PA, but ETAD-stimulated rates decreased $(P<.04).$ Basal, E-$(P=.22),$ and NE-stimulated $(P=.31)$ IVFA release rates were similar between C and PA. (Abstract shortened by UMI.)

Type of Resource

text

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http://hdl.handle.net/2142/19981

Copyright and License Information

Copyright 1996 Reiling, Bryan Alan

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