Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract only
Publication Acceptance Date: 9/1/1997
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: When fed pine needles(PN), elk do not abort and do not have increased vasoconstrictive activity (VA) in plasma as do cattle. These experiments were conducted to determine if transferring ruminal fluid (RF) from elk to cattle or if diets high in fat (HF) will prevent PN abortions in cattle or if in vitro incubation of elk RF with PN will decrease VA of PN. In Exp. 1, pregnant cattle were assigned to receive RF collected from steers (S) or female elk (E). Ruminal contents were collected via ruminal fistula, filtered through cheese cloth, and the RF (1-2 L) transferred by gavage to pregnant (247 d) cattle at -13, -10, -7, -4, and 0 d from the start of PN feeding (2 kg/d). In Exp. 2, the treatments and protocols from Exp 1 were repeated with the addition of a group that was fed a diet high in fat (HF) for 30 d before PN feeding started. In Exp. 3, RF from 5 different collections from S and E were incubated in vitro with 0 or 25% PN in the substrate for 48 hr. Methylene dichloride extracts of these incubates were assayed for VA . In Exp. 1, ERF delayed parturition in 2 of 4 cows as compared to 0 of 8 in the SRF group (interval to parturition = 11.3 vs 6.5 d, P = .1). In Exp. 2, there was no effect of HF or ERF on interval to parturition (HF = 4.5, ERF = 6.5, and SRF = 4.8 d; P > .2). In Exp. 3, ERF reduced VA (change between 0 and 25% PN in baseline perfu- sion pressure, SRF = 6.25%, ERF = 0%; P < .05 and in perfusion pressure after membrane depolarization, SRF = 60%, ERF = -21%; P < .1). We conclude dietary fat does not affect abortifacient effects of PN, that ERF decreases VA of PN, and that in vivo transfer of ERF to cattle elicited some response, but it was not sufficient to affect a majority of cattle.