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The effects of oral drenching with Co or vitamin B12, drenching frequency and Co via rumen bolus on plasma vitamin B12 concentration in weaned lambs

Hession, D.V.; Kendall, N.R.; Hanrahan, J.P.; Keady, T.W.J.


D.V. Hession

J.P. Hanrahan

T.W.J. Keady


Weaned lambs (n = 88) were stratified by sex and body weight (BW) and allocated at random to 1 of 10 treatments for 12 weeks (consecutive 6-week periods), to evaluate the effects of supplementation with Co or vitamin B12 (B12) on the concentrations of B12 in blood plasma. The treatments were: no supplementation (Control); rumen bolus containing Co only (Bolus); and oral administration of a liquid solution (Drench) containing Co or B12 at intervals of 1, 2, 3 or 6 weeks. One bolus (expected Co release [by leaching] of 0.8 mg/day for 4 months) was administered to the bolus group at the initiation of the study (day 0). The lambs on the drench treatments received totals of 63 mg Co (as CoSO4·7H2O) or 34.5 mg B12 over each 6-week period; drench concentrations were 2.1 mg/ml and 2.3 mg/ml for Co and B12, respectively. The lambs were managed in a rotational-grazing system on predominately perennial ryegrass swards. Blood samples were collected weekly (immediately prior to treatment administration), starting on day 0, and plasma was analysed for B12 and Co. Lambs on the Co-drench treatments had higher B12 concentrations (P < 0.001) than the Control in both 6-week periods but the difference exhibited a quadratic decline in both periods as the drenching interval increased (P < 0.001). Drenching with B12 increased plasma B12 concentration in both periods but the difference only reached significance (P < 0.05) in the second period and the effect of drenching frequency was not significant in either period. Lambs on the Co-drench had higher (P < 0.01) plasma B12 concentrations than lambs on the B12-drench treatments, and the control. Bolus lambs had a higher plasma B12 concentration (P < 0.01) than lambs drenched with Co at 2-, 3- or 6-week intervals in the first 6-week period but did not differ (P > 0.05) from these treatments in the second period. Lambs on the Bolus treatment had a higher plasma B12 concentration than Control lambs over the first (P < 0.001) and second (P < 0.05) periods. It is concluded that drenching with Co is more effective than drenching with B12, in terms of the effect on plasma B12 concentration. Drenching with Co at intervals of 1 or 2 weeks was more effective than drenching at intervals of 3 or 6 weeks. While the bolus treatment was effective in increasing plasma B12 concentration compared to Control over weeks 1 to 12, the difference between these treatments declined significantly over time.


Hession, D., Kendall, N., Hanrahan, J., & Keady, T. (2022). The effects of oral drenching with Co or vitamin B12, drenching frequency and Co via rumen bolus on plasma vitamin B12 concentration in weaned lambs. Livestock Science, 266, Article 105108.

Journal Article Type Article
Acceptance Date Oct 21, 2022
Online Publication Date Oct 22, 2022
Publication Date 2022-12
Deposit Date Nov 23, 2022
Publicly Available Date Oct 23, 2023
Journal Livestock Science
Print ISSN 1871-1413
Publisher Elsevier BV
Peer Reviewed Peer Reviewed
Volume 266
Article Number 105108
Keywords General Veterinary; Animal Science and Zoology
Public URL
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