@conference {40551, title = {The relationship between internal parasite burden, faecal egg count, and mucosal mast cells in fleeceweight-selected and control sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {54}, year = {1994}, month = {Jan}, pages = {9-14}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Research has shown that sheep from a Massey University flock selected for increased fleece weight (FW) for thirty-six years have higher faecal egg counts (FEC) than unselected controls (C). The purpose of this trial was to determine whether differences in FEC between FW and C sheep accurately reflected differences in adult worm burdens. In addition levels of mucosal mast cells, and their relationship with worm burden in each line were examined. Thirteen one year-old rams from each flock were housed indoors and artificially infected with larvae of three species of nematode parasite: Haemonchus contortus, Ostertagia circumcincta, and Trichostrongylus colubriformis. FECs were monitored and adult worm burdens, and levels of mucosal mast cells, determined following slaughter 28 days after infection. FECs were higher in FW than C sheep (4204 vs 300 epg, p<0.0001), as were numbers of adult Haemonchus (1151 vs 249, p<0.01) and Ostertagi (2268 vs 600, p<0.05). Numbers of Trichostrongylus (5838 vs 5266) and total worm burden (9257 vs 6115) were not significantly different between lines. A {\textquoteright}Total Pathogenic Index{\textquoteright}, calculated from the number of parasites of each species present in the total burden, was higher in FW than C sheep (3.8 vs 1.5, p<0.005). The regression coefficient relating FEC to worm burden was larger in FW than C sheep (0.35 vs 0.05 eggs per g faeces/worm, p<0.01). Levels of mucosal mast cells did not differ significantly between lines, but were inversely related to number of worms in FW sheep. There was no such relationship in C sheep. It is concluded that while the large differences in FEC between lines overestimates the difference in total worm burden, FW sheep do carry significantly more worms of the abomasal species H. contortus and O. circumcincta than C sheep. FW sheep are able to maintain superior wool production in spite of this potentially more pathogenic worm burden. The mucosal mast cell response to parasitic infection also appears to have been changed by selection. }, issn = {1176-5283}, author = {Williamson JF and Blair HT and Garrick DJ and Pomroy WE and Douch PGC} } @conference {40219, title = {The sheep{\textquoteright}s immune response to nematode parasites and prospects for its exploitation}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {50}, year = {1990}, month = {Jan}, pages = {229-236}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Perennial ryegrass (RG) and Matua prairie grass swards of low (LMPG) and high (HMPG) pre-grazing herbage masses were compared in 8 grazing trials (2-3 weeks) during early spring, late spring, summer and autumn (1987/88 and 1988/89) to assess their feeding values. Pre- grazing masses were approximately 3000, 4000 and 5500kg DM/ha for RG, LMPG and HMPG treatments, respectively. Friesian cows (8 per treatment) were allowed 50 kg DM/cow/d. Mean concentrations of N (\% in OM) and OMD (\%) for RG, LMPG and HMPG herbage were 2.7, 2.6, 2.3 (s.e.lsm 0.04, P<0.001); and 74.7, 73.1 and 70.7 (s.e. 0.18, P<0.001), respectively, HMPG values were lowest during all seasons and were influenced by high compositions of dead material, low leaf:stem ratios and low compositions of clover in the swards. Daily yields of milk and protein on RG swards were 3\% higher (P<0.05) than LMPG yields, and 11 and 13\% higher (P<0.001), respectively than those of HMPG swards. Milkfat yields were similar on RG and LMPG swards, but were 11\% lower (P<0.001) on the HMPG treatment. The results indicate that leafy prairie grass and leafy ryegrass swards have similar feeding and productive values. Further research is needed on Matua{\textquoteright}s persistence under grazing. }, issn = {1176-5283}, author = {Douch PGC} }