Physiological changes and digestive capabilities of newly received feedlot cattle

S. C. Loerch, F. L. Fluharty

Research output: Contribution to journalArticlepeer-review

109 Scopus citations


Newly arrived feedlot calves undergo numerous stressors that result in 1) transient endocrine responses, 2) altered products of energy and protein metabolism, 3) changes in appetite and growth rate, 4 ) possible limited compromise of digestive and rumen function, and 5) a challenged immune system. The most consistent endocrine and metabolic responses to marketing, transport, and feedlot adaptation are seen with cortisol and epinephrine. In contrast to earlier work done with indirect in vitro gas production measurements, recent research has shown that the ruminal microbial population is able to effectively digest available substrate immediately following a calf s weaning, trucking, and 24 h of feed and water deprivation. Additionally, a period of feed and water deprivation up to 72 h coupled with 8 h of trucking does not reduce the concentration or total numbers of either the viable cellulolytic or total bacteria present in the rumen of newly weaned or feedlot-adapted calves. However, ruminal volume, DM, total weight of ruminal contents, and total protozoal numbers decrease as duration of feed deprivation increases. To compensate for the reduced DMI that occurs in the first 2 wk after arrival at the feedlot, increased nutrient density is needed to meet an animal's requirements for nutrients. Limited data suggest that newly arrived calves prefer a diet that is similar in moisture and texture to feeds with which they are familiar. Additionally, modification of the stress-associated behavior using trainer animals may improve the feed intake of newly received calves and may reduce calf morbidity.

Original languageEnglish (US)
Pages (from-to)1113-1119
Number of pages7
JournalJournal of animal science
Issue number5
StatePublished - May 1999

All Science Journal Classification (ASJC) codes

  • Food Science
  • Animal Science and Zoology
  • Genetics


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