The effect of mineral supplementation on production parameters and gastrointestinal competence of calves on pasture: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science with Honours at Lincoln University

Abstract

Forty three, eight month old calves grazing pastures adequate of copper and cobalt status were allocated to four groups, - Group 1 ( 11 calves) copper plus selenium, - Group 2 ( 11 calves) vitamin B12 plus selenium - Group 3 ( 11 calves) copper plus vitamin B12 plus selenium - Group 4 (10 calves) selenium only. Pasture elemental levels, liveweights, plasma pepsinogens, faecal egg counts, and serum copper and cobalt levels were all measured prior to the administration of the treatment on 5 April. Following the initial measurements, liveweights were monitored regularly through out the trial. Plasma pepsinogen levels were again measured on 7 May and 2 August and serum copper and cobalt levels were measured on 2 August. The faecal egg count averaged 356 epg. Initial copper and cobalt serum levels were adequate, 13 umol/L and 355pmol/L respectively. Copper treatment in the form of COWP produced a significant difference in serum copper levels for group 3 only, and after treatment the mean serum copper levels of all groups declined from 13, 41 umol/L to 11.72 umol/L 5000ug of hydroxycobalamin failed to produce a significant difference between treatment groups, or a significant increase in vitamin B12 levels. The growth response declined over the period of the trial with growth rates for period 1, 2, 3 being 0.50, 0.36, -0.11 kg/d respectively. No significant difference between treatment groups following treatment was obtained ( for plasma pepsinogen levels. However, post treatment administration mean plasma pepsinogen levels were reduced significantly over the period of the trial, 1.68, 0.69, 0.95 IU/l for 5 April, 7 May, 2 August respectively, possibly as a result of regular anthelmintic treament. In conclusion, calves with adequate serum copper and cobalt levels did not produce a significant growth .response following supplementation. It was extremely difficult to raise serumt levels of calves with adequate copper and cobalt status. Ideally liver biopsies would be required required to produce more accurate measurements of the copper and cobalt status. From these results it is difficult to postulate whether the calves nematode burden is affected by low or a high copper or cobalt status.