Enhanced reproductive performance of ewes given a sustained-release multi-trace element/vitamin ruminal bolus

A sustained-release multi-trace element/vitamin bolus has been devised for administration to ewes in advance of mating. Each bolus contained 5.3 g Cu, 50 mg Se, 90 mg Co, 100 mg 1, 3.2 g Mn and 4.7 g Zn with 268 x 10(3) IU Vitamin A, 54 x 10(3) IU Vitamin D and 800 IU Vitamin E, About 50% of each nutrient is released during the first 6 weeks. Thereafter the release rate slows and over the remaining life of the bolus (about 6 months extending to lambing time) the daily release rates are about 15 mg: Cu, 0.1 mg Se, 0.2 mg Co, 0.3 mg 1, 9.4 mg Mn and 13 mg Zn with 775 IU Vitamin A, 156 IU Vitamin D and 2 IU Vitamin E, In one study the proportion of twins born to ewes given the bolus was very significantly (P < 0.001) higher than for the untreated ewes and greater than for those given a copper injection or copper oxide needles. In a second study the proportion of ewes given a bolus and having twin lambs was significantly (P < 0.01) greater than for untreated ewes and significantly (P < 0.05) fewer ewes were non-pregnant. Tn a third study, giving a bolus to shearling eu;es tended (P = 0.06) to result in fewer non-pregnant animals: than for those untreated. Blood copper and Vitamin B(12) concentrations and glutathione peroxidase activities were above normal values throughout. (C) 2001 Elsevier Science B.V. All rights reserved.