Search

The concentration of Co in the herbage of a large proportion of grassland farms in Ireland is lower than that required by sheep. The effects of supplementing ewes with Co, and method of supplementation, on ewe and offspring performance, were evaluated over 2 years. The ewes (359 in year 1, 241 in year 2), representing 3 genotypes, were allocated to one of 3 treatments. The treatments were: Control - no supplementation; Drench – Co supplementation via oral drench (31.5 mg Co as CoSO4•7H2O) administered every 14 days; Bolus – Co supplementation via rumen bolus (effective life of ∼6 months) that only contained Co as CoSO4•7H2O with an expected Co release rate of 0.6 mg/day in year 1 and 1 mg/day in year 2. Drench treatment was administered from 7 weeks pre joining, until 6 weeks prior to expected lambing date (early – to mid - March). One bolus was administered to ewes on the bolus treatment at the start of the study (day 0) each year. The ewes were managed as one flock in a rotational-grazing system until housing in early December each year; they were shorn at housing and offered grass silage ad libitum plus a concentrate supplement during late pregnancy. Ewes and lambs were put to pasture within 3 days of lambing. Supplementation with Co, via drench or bolus, increased the concentration of Co (p 0.05) on ewe BW or body condition score at joining (day 49), mid-pregnancy, lambing, 5 weeks post lambing or weaning. Likewise, supplementation had no effect (p > 0.05) on litter size, lamb mortality or number of lambs reared per ewe joined, or on lamb BW at birth or weaning. The only significant animal-performance difference detected between the Bolus and Drench treatments concerned the incidence of lambs classified as ‘born dead or died within 24 h of birth’ (3.1% for Drench, 6.5% for Bolus; p

Cobalt and selenium are essential trace elements required for ruminants. There are many different methods of supplementation available to sheep including boluses, in feed, free access minerals, pasture dressing and oral drenches. Recent changes in European legislation have resulted in a reduction in the maximum permitted level (MPL) of cobalt to be included in ruminant diets from 2 mg/kg at 88% DM to 1 mg/kg at 88% DM with a suggested supplementary rate of 0.3 mg Co/kg at 88% DM. This study aimed to determine the efficacy of cobalt plus/minus vitamin B₁₂ and selenium supplementation from oral drenching over a 13 day time period. Seven groups of grass silage fed Suffolk cross mule lambs (n=56) were randomly allocated to one of 7 treatments, a 5 ml oral drench containing 700, 2300, 12000 mg Co/l, with or without 2300 mg vitamin B₁₂/l in a factoral design, with an additional control group which received no drench. All drenches also contained selenium at 625 mg/l. Lambs were weighed on days 0 and 13. The lambs were sampled by jugular venepuncture on days 0, 1, 2, 3, 4, 5, 6, 7, 9, 11 and 13, with samples analysed for plasma selenium and cobalt by ICP-MS, erythrocyte glutathione peroxidase by colourimetric assay and vitamin B₁₂ by immunoassay. The results showed that cobalt via a drench was able to raise plasma cobalt in a dose dependent manner, with each dose level significantly higher than the previous level at all post drenching time points (P

Zinc, cobalt and selenium are essential trace elements for ruminants and all have roles in immune function. The delivery of these elements to grazing livestock can be problematical. The aim of this trial is to determine the effect of the administration of an intraruminal soluble glass bolus to supply zinc, cobalt and selenium to growing lambs at pasture and to determine the effect on humoral immune response via the administration of a novel keyhole limpet haemacyanin (KLH) antigen. On days 0, 17 lambs each had a zinc (15.1% w/w), cobalt (0.52% w/w) and selenium (0.15% w/w) soluble glass bolus (∼33 g) administered (bolused), whilst the 17 lambs received no bolus (control). All of the lambs were grazed together throughout the trial. Trace element status (selenium—erythrocyte glutathione peroxidise activity; cobalt—serum vitamin B12 concentration; zinc—plasma zinc concentration) and live weights were assessed on days 0, 20, 42 and 63, with immunisation with KLH on day 34 and assessment of IgG response by direct ELISA on days 20, 42, 49, 63. Lambs were slaughtered when commercially fit on either day 86 or 121 and livers analysed for copper and zinc concentrations and boluses recovered from the bolus group to assess dissolution rates. The bolused lambs had significantly increased serum vitamin B 12 concentrations ( p p p p p p In conclusion, administration of a zinc, cobalt and selenium soluble glass bolus resulted in an increased antibody response and fulfilled the daily requirements for cobalt, selenium and zinc with an elevated status of these elements compared to unsupplemented controls grazing the same pasture.