Abstract
Effects of early weaning calves on serum metabolites and hepatic insulin-like growth factor-1 messenger RNA (IGF-1 mRNA) of first-calf heifers or mature cows was investigated. Treatments were arranged in a 2 x 2 factorial and included 14 crossbred first-calf heifers and 14 crossbred mature cows assigned randomly to one of two treatment regimens: early-weaned (EW, calves weaned at an average age of 114 d) or normal-weaned (NW, calves weaned at an average age of 197 d). Blood samples were collected from dams on d 114, 141, 197 and 205 postpartum via coccygeal venipuncture. Heifers with calves EW experienced a greater increase (parity x weaning; P = 0.02) in BW over heifers with calves NW, but no change in BW due to weaning was observed for mature cows (P>0.71). Early weaning (vs. NW) increased (P<0.05) body condition (BC) and change in BC of heifers and cows. Effects of weaning regimen or parity were not observed for ADG. There were no parity x weaning or parity x weaning x d interactions (P>0.16) observed for serum IGF-1, serum non-esterified fatty acids (NEFA), or serum urea nitrogen (SUN). A parity x d interaction (P<0.05) for hepatic IGF-1 mRNA, serum IGF-1 and SUN, and a trend for parity x d for NEFA (P<.0.10) were observed, but no differences were detected between first-calf heifers and mature cows within sampling d. Early weaning tended to decrease (P = 0.06) SUN compared with NW status. These results suggest that EW can increase BW and BC in first-calf heifers, and decrease SUN in both first-calf heifers and mature cows. However, no other differences in performance or serum chemistry were detected between first-calf heifers and mature cows with either weaning regimen applied, in open rangeland conditions of the arid southwest United States during drought.
Original language | English (US) |
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Pages (from-to) | 49-53 |
Number of pages | 5 |
Journal | Journal of Food, Agriculture and Environment |
Volume | 4 |
Issue number | 2 |
State | Published - Apr 2006 |
Keywords
- Beef cattle
- Cows
- Early weaning
- Grazing
- Heifers
- Insulin-like growth factor-1
- Livestock production
- Metabolism
- Parity
- Serum chemistry
ASJC Scopus subject areas
- Food Science
- Agricultural and Biological Sciences (miscellaneous)
- Environmental Science(all)