Sandi L. Parr

Document Type

Thesis - University Access Only

Award Date

2007

Degree Name

Master of Science (MS)

Department / School

Animal Science

Abstract

Two experiments were used to test the effect of implant dose and delivery pattern. In Exp. I effect of delivery pattern was tested in steers (n= l92; BW=372 kg). Overall, all implant treatments (IMP) except control (CON) provided 24 mg estradiol-17~ (E2) and 120 mg trenbolone acetate (TBA). The following doses of E2 and TBA in milligrams were given; 2) 8E2!'40TBA on d 0, 42, and 84; 3) 12E2/60TBA on d O and 63; and 4) 24E2/120TBA on d 0. Steers were split into two frame sizes (FS; FSL = larger; FSS = smaller). Blood was collected on d -1 , 41, 62, 83 , and 125 for plasma urea-N (PUN) analysis as a relative indicator of anabolism. No IMP x FS interaction occurred for steer performance or carcass traits. Cumulatively (133 d) implants caused higher ADG (1.42 vs. 1.58 kg; P < 0.05) and improved G:F (0.139 vs. 0.150 kg/kg; P < 0.05) compared to CON. Steers on IMP 3 had lower DMI (10.3 vs. 10.83 kg; P < 0.05) and higher G:F (0.155 vs. 0.145 kg/kg; P < 0.05) compared to IMP 4. Delivery pattern did not affect cumulative ADG but the pattern of growth differed. During 1 to 63 d, the change in ADG relative to CON was 6.8, 5.0, and 11.8% for IMP 2, 3 and 4, respectively. From d 64 to 133, the response in ADG was 19.5, 16.6, and 11.3%, respectively. Implanting increased (P < 0.05) HCW vs. CON and marbling was not affected by IMP. Plasma urea-N increased with time and was subject to an IMP x FS interaction. In FSL, CON PUN tended (P < 0.10) to be higher at d 41 and 62 vs. IMP 3 and 4. In FSS CON and IMP 4 caused higher (P < 0.05) PUN vs. IMP 2 and 3 throughout the experiment. In Exp. II the effect of implant dosage was determined using steers (n=64; BW=368 kg) which received the following anabolic dosages; 1) no implant; 2) 8:Ei/40TBA; 3) 16:Ei/80TBA; 4) 24:Ei/120TBA. Blood was drawn (n=40) on d 0, 2, 7, 14, 21, 28, 42, and 70 for PUN testing. Implants increased 136 d ADG (1.2c, 1 .4\ 1 .4\ and 1.6a kg/d; P < 0.05) and HCW (330\ 347\ 345\ and 362a kg; P < 0.05). At d 21 , 28, and 42 CON and IMP 3 resulted in higher (P < 0.05) PUN compared to IMP 2 and 4. At d 70 CON had higher (P < 0.05) PUN compared to IMP 2, 3, and 4. Steers in lMP 3 had twice the anabolic dose vs. IMP 2, but PUN was lower for IMP 2. Plasma urea-N were similar between IMP 2 and 4 despite dosage differences. In Exp. I, multiple, low doses of~ and TBA caused a slower decline in growth vs. cattle receiving a single high dose. Smaller framed steers had increased response to multiple low doses via PUN analysis.

Library of Congress Subject Headings

Beef cattle

Anabolic steroids

Growth factors

Format

application/pdf

Number of Pages

72

Publisher

South Dakota State University

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