Effects of a mixed nematode infection on net calcium and phosphorus absorption in lambs : A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science with Honours at Lincoln College

Abstract

1. Twelve 4 month old lambs, raised on pasture and given an anthelminitic drench, were allocated to 4 pair feeding blocks. Within each block the treatments given were zero larval dose (PFC) , a daily dose of 2000 Trichostrongylus colubriformis larvae (TC), and a daily dose of 2000 T. colubriformis larvae and 4000 ostertagia circumcincta larvae (TC+ OC). Group TC+ OC lambs were fed ad libitum a fresh herbage diet cut daily from a parasite free paddock. PFC and TC lambs were pair fed the same diet to the TC + OC intakes. Digestibility and apparent absorption studies were done weekly . Lambs were slaughtered on day 66 of infection.

2. Digesta flow was measured using the radioactive markers (51cr) EDTA and (103Ru)- Phenanthroline, continually infused over the last 7 days . Feed was given in equal amounts every 2 hours during the infusion period. Whole sampling of the digesta contents of the abomasum and terminal ileum was done at slaughter. Ca and P flows were determined.

3. There were no consistent differences in the apparent absorption of Ca and P throughout the whole period. Differences that did occur were attributed to the difficulty of sampling diarrhoeic lambs.

4. There were no significant differences (P> 0.05) in any of the Ca or P parameters measured between treatments. This was due to large individual variation of which the causes are discussed.

5. There was a trend for a lower net absorption in the small intestine of infected lambs (6.2, 1.5 and 1.5 g P/day for the PFC, TC and TC+ OC lambs respectively). Salivary P flow also appeared to be reduced (6.2, 3.0 and 2.6 g/day for the PFC, TC and TC + OC lambs respectively).

6. Plasma P levels (45 mg P/1, TC; 52 mg P/1, TC+ OC) were significantly lower (P<0.05) than the 70 mg P/l maintained in PFC lambs up to week 10. The cumulative liveweight gain was higher for PFC lambs from weeks 8 to 10. Consequently empty body weights of PFC lambs were higher (P<(0 .05) at slaughter (25.2 kg, PFC; 23.3 kg, TC; 22.2 kg , TC+ OC).

7. There was no additive effect of a concurrent infection of o. circumcincta with T. colubriformis infection on any of the Ca and P parameters or on the observed weight changes.