Hormonal growth-promotant effects on grain-fed cattle maintained under different environments

Gaughan, J. B., Kreikemeier, W. M. and Mader, T. L. (2005) Hormonal growth-promotant effects on grain-fed cattle maintained under different environments. International Journal of Biometeorology, 49 6: 396-402. doi:10.1007/s00484-005-0254-6

Author Gaughan, J. B.
Kreikemeier, W. M.
Mader, T. L.
Title Hormonal growth-promotant effects on grain-fed cattle maintained under different environments
Journal name International Journal of Biometeorology   Check publisher's open access policy
ISSN 0020-7128
Publication date 2005-01-01
Year available 2005
Sub-type Article (original research)
DOI 10.1007/s00484-005-0254-6
Open Access Status Not yet assessed
Volume 49
Issue 6
Start page 396
End page 402
Total pages 7
Editor Masaaki Shibata
Place of publication New York
Publisher Springer
Language eng
Subject C1
630103 Beef cattle
300406 Animal Growth and Development
Abstract Six steers (3/4 Charolaisx1/4 Brahman) (mean body weight 314 +/- 27 kg) and six spayed heifers (3/5 Shorthornx2/5 Red Angus) (mean body weight 478 +/- 30 kg) were used to determine the effects of climatic conditions and hormone growth promotants (HGP) on respiration rate (RR; breaths/min), pulse rate (beats/min), rectal temperature (RT; degrees C), and heat production (HP; kJ). Cattle were exposed to the following climatic conditions prior to implantation with a HGP and then again 12 days after implantation: 2 days of thermoneutral conditions (TNL) [21.9 +/- 0.9 degrees C ambient temperature (T-A) and 61.7 +/- 22.1% relative humidity (RH)] then 2 days of hot conditions [HOT; 29.2 +/- 4 degrees C (T-A) and 78.3 +/- 13.2% (RH)], then TNL for 3 days and then 2 days of cold conditions [COLD; 17.6 +/- 0.9 degrees C (T-A) and 63.4 +/- 1.8% (RH); cattle were wet during this treatment]. The HGP implants used were: estrogenic implant (E), trenbolone acetate implant (TBA), or both (ET). Both prior to and following administration of HGP, RRs were lower (P < 0.05) on cold days and greater (P < 0.05) on hot days compared to TNL. On hot days, RTs, were 0.62 degrees C higher after compared to before implanting. Across all conditions, RTs were > 0.5 degrees C greater (P < 0.05) for E cattle than for TBA or ET cattle. On cold days, RTs of steers were > 0.8 degrees C higher than for the heifers, while under TNL and HOT, RTs of steers were 0.2-0.35 degrees C higher than those of heifers. Prior to implantation, HP per hour and per unit of metabolic body weight was higher (P < 0.05) for cattle exposed to hot conditions, when compared to HP on cold days. After implantation, HP was greater (P < 0.05) on hot days than on cold days. Under TNL, ET cattle had the lowest HP and greatest feed intake. On hot days, E cattle had the lowest HP, and the highest RT; therefore, if the potential exists for cattle death from heat episodes, the use of either TBA or ET may be preferred. Under cold conditions HP was similar among implant groups.
Keyword Beef Cattle
Environmental Stress
Hormone Growth Promotants
Environmental Sciences
Meteorology & Atmospheric Sciences
Feedlot Cattle
Thermoregulatory Responses
Trenbolone Acetate
Roughage Diets
Q-Index Code C1
Institutional Status UQ
Additional Notes (DOI) 10.1007/s00484-005-0254-6

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Created: Wed, 15 Aug 2007, 16:04:34 EST