Linked Life Data

16699120

Source:http://linkedlifedata.com/resource/pubmed/id/16699120

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2006-5-15
pubmed:abstractText
An 84-d grazing experiment was conducted in 2 growing seasons to evaluate interactions of stocking rate and steroidal implants with BW gain and symptoms of toxicosis in yearling steers grazing endemic endophyte-infected (E+) tall fescue (Festuca arundinacea Schreb.). A 4 x 2 factoral design was used to evaluate 4 stocking rates (3.0, 4.0, 5.0, and 6.0 steers/ ha) with or without steroidal implants (200 mg of progesterone + 20 mg of estradiol benzoate). Treatment combinations were randomly assigned to eight 1-ha pastures of E+ Kentucky-31 tall fescue (i.e., treatments were not replicated). Treatment effects were analyzed for ADG, total BW gain per hectare, forage availability, and hair coat ratings. At the conclusion of grazing in the second year (22 June), steers were placed on a bermudagrass [Cynodon dactylon (L.) Pers.] pasture, and rectal temperatures and serum prolactin concentrations were monitored for 10 d to assess carryover effects of stocking rate and steroidal implants on recovery from toxicosis-related heat stress. Forage availability differed (P < 0.001) between years, but there were no year x treatment interactions (P > 0.10). There was an implant x stocking rate interaction (P < 0.05) on ADG. Differences between the slopes in the regression equations indicated that ADG responded to implantation when stocking rates were low, but the response diminished as stocking rate increased. Stocking rate did not influence (P = 0.89) postgraze rectal temperature, but the regression intercept for implanted steers was 0.4 degrees C greater (P < 0.05) than for nonimplanted steers, and the difference was consistent across the entire 10-d fescue-free grazing period. Concentrations of prolactin increased during the 10-d fescue-free grazing period, but trends differed due to an implantation x stocking rate interaction (P < 0.05). Results indicate that implantation with progesterone + estradiol benzoate increases ADG with lower stocking rates, but the effect diminishes with increased grazing intensity. Implantation with steroid hormones increased rectal temperatures, but during a fescue-free grazing period rectal temperatures and serum prolactins for implanted and nonimplanted steers returned to values indicative of a stable and healthy status in a 192- to 240-h (i.e., an 8- to 10-d) period. However, because the treatments used in this study were not replicated, these observations need to be confirmed with replicated studies.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1525-3163
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
84
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1626-32
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Influence of stocking rate and steroidal implants on growth rate of steers grazing toxic tall fescue and subsequent physiological responses.
pubmed:affiliation
Forage-Animal Production Research Unit, USDA-ARS, Lexington, KY 40546, USA. geaiken@ars.usda.gov
pubmed:publicationType
Journal Article, Randomized Controlled Trial