Expression of worm resistance in sheep selected for low worm-egg counts fed at maintenance or above-maintenance level

2019 ◽  
Vol 59 (10) ◽  
pp. 1783 ◽  
Author(s):  
J. C. Greeff ◽  
S. M. Liu ◽  
D. G. Palmer ◽  
L. J. E. Karlsson
Keyword(s):  
Developmental Stages ◽  
Significant Decline ◽  
Control Line ◽  
Restricted Feeding ◽  
Trichostrongylus Colubriformis ◽  
Concomitant Change ◽  
Infective Larvae ◽  
Teladorsagia Circumcincta ◽  
Resistant Lines

The present study reports on changes in faecal worm-egg counts (WEC), larval composition, and the number of worms at different developmental stages in young sheep sourced from a flock selected for reduced faecal worm-egg counts over 15 years. The sheep were individually penned and fed a maintenance (1.0 M) or a 1.5 times maintenance (1.5 M) diet over two periods, namely, worm-free and infection phases. They were dosed weekly with 10000 Trichostrongylus colubriformis and 10000 Teladorsagia circumcincta L3 infective larvae for 11 weeks. Sheep on the 1.5 M diet had lower WEC and higher bodyweights than did sheep on the 1.0 M diet. A significant decline in the percentage T. colubriformis occurred during the experiment, but no concomitant change in T. circumcincta was noticed. Resistant sheep had significantly (P < 0.001) fewer worms at necropsy, and also shed significantly (P < 0.001) fewer worm eggs during the experiment. Restricted feeding reduced bodyweight significantly (P < 0.001) and had a small but significant (P < 0.04) effect on the faecal worm-egg output and on the number of T. colubriformis worms (P < 0.01) in both the control and resistant sheep. The study showed that sheep selected for low WEC resulted in significantly (P < 0.001) lower WEC than in an unselected control line fed at a maintenance (1.0 M) and at an above-maintenance (1.5 M) level. Restricted feeding reduced bodyweight and had a small negative, and inconsistent, effect on the faecal worm-egg output in both the control and resistant lines.

Lack of efficacy of monepantel against Teladorsagia circumcincta and Trichostrongylus colubriformis

2013 ◽  
Vol 198 (1-2) ◽  
pp. 166-171 ◽  
Author(s):  
I. Scott ◽  
W.E. Pomroy ◽  
P.R. Kenyon ◽  
G. Smith ◽  
B. Adlington ◽  
...  
Keyword(s):  
Trichostrongylus Colubriformis ◽  
Teladorsagia Circumcincta

scholarly journals Retrieval of Trichostrongylus colubriformis infective larvae from grass contaminated in winter and in spring

2014 ◽  
Vol 23 (4) ◽  
pp. 463-472 ◽  
Author(s):  
Raquel Abdallah da Rocha ◽  
Patrizia Ana Bricarello ◽  
Gilberto Pedroso da Rocha ◽  
Alessandro Francisco Talamini do Amarante
Keyword(s):  
Forage Grasses ◽  
Trichostrongylus Colubriformis ◽  
Fecal Samples ◽  
Infective Larvae ◽  
Retrieval Rate ◽  
Experimental Plots

The survival of infective larvae (L3) of Trichostrongylus colubriformis was evaluated on Brachiaria, Coast-cross and Aruana forage grasses. Feces of sheep parasitized exclusively by T. colubriformis were deposited in winter and spring on experimental plots whose grasses were cut at two heights: 5 cm and 30 cm. One, two, four, eight, 12 and 16 weeks after depositing the feces, fecal and forage samples were collected for the retrieval and quantification of L3. Retrieval of L3 from feces and forage was negligible in winter due to the dry weather, although a few larvae were retrieved in the last larval collections. However, L3 retrieval from fecal samples was greater in spring, especially two weeks after feces were deposited on 30 cm high grasses. At this time, the L3 retrieval rate from the three forage grasses differed significantly (P <0.05), with Aruana grass showing the highest average L3 retrieval rate, followed by Coast-cross and Brachiaria. In conclusion, the winter drought proved very unfavorable for the presence of L3 in the environment, and the microclimate of Aruana pastureland was generally the most favorable for the retrieval of infective larvae.

scholarly journals Recovery of Trichostrongylus colubriformis infective larvae from three grass species contaminated in the autumn

2012 ◽  
Vol 21 (4) ◽  
pp. 372-378 ◽  
Author(s):  
Raquel Abdallah da Rocha ◽  
Patrizia Ana Bricarello ◽  
Gilberto Pedroso da Rocha ◽  
Alessandro Francisco Talamini do Amarante
Keyword(s):  
Dry Matter ◽  
Cynodon Dactylon ◽  
Larval Survival ◽  
Grass Species ◽  
Panicum Maximum ◽  
Free Living ◽  
Trichostrongylus Colubriformis ◽  
Brachiaria Decumbens ◽  
Infective Larvae ◽  
Experimental Plots

This experiment aimed to assess the recovery of infective larvae (L3) of Trichostrongylus colubriformis from Brachiaria decumbens cv. Australiana, Cynodon dactylon cv. Coast-cross and Panicum maximum cv. Aruana. The experimental module comprised six plots, with two plots per herbage species. Larval survival was assessed from autumn to winter, under the effect of two herbage-paring heights (5 and 30 cm). TThe paring was carried out immediately before contamination with faces containing T. colubriformis eggs. The feces and herbage were collected at one, two, four, eight, 12 and 16 weeks after feces had been deposited in the experimental plots. In general, larvae were recovered from both herbage and feces until the 16th week. The longer persistence of these larvae in the environment was probably due to warmer temperatures. The number of L3 recovered from the pasture was not influenced by the height of plants, except for Brachiaria and Aruana herbage in the fourth week. Regarding the concentrations of larvae per kg of dry matter (L3/kg DM), recovery was higher from low pasture in all three herbage species. During the autumn, the development and survival of the T. colubriformis free-living stages were not affected by the different herbage species.

scholarly journals Effects of condensed tannins on established populations and on incoming larvae of Trichostrongylus colubriformis and Teladorsagia circumcincta in goats

2003 ◽  
Vol 34 (3) ◽  
pp. 331-339 ◽  
Author(s):  
Virginie Paolini ◽  
Audrey Frayssines ◽  
France De La Farge ◽  
Philippe Dorchies ◽  
Hervé Hoste
Keyword(s):  
Condensed Tannins ◽  
Trichostrongylus Colubriformis ◽  
Teladorsagia Circumcincta
Sign in / Sign up

Export Citation Format

Share Document