Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 12/10/2007
Publication Date: 2/5/2008
Citation: Appeddu, L., Brown, M.A., Hart, S. 2008. Evaluation of parasite load in hair- or wool-type on pasture or drylot settings [abstract]. American Society of Animal Science Southern Section Meeting, February 4-5, 2008, Dallas, TX. p. 32. Available on-line: http://www.asas.org/southern/meetings_past.asp.
Interpretive Summary: Abstract Only.
Technical Abstract: Internal parasites are a major health issue in small ruminants and are responsible for significant economic losses. The objective of this research was to evaluate effects of breed type and diet on internal parasite infestation in purebred St. Croix (hair; H), Dorset (wool; W), and crossbred (HxW) fall-born lambs. In 2006, lambs were on drylot (H: n=6; W: n=6) and sampled early March and April and late April. In 2007, lambs grazed wheat (H: n=3; W: n=3; HxW: n=4) and were sampled in mid-February, early March, late March, and late April. In 2007, approximately half of the lambs in each breed type were supplemented with ground corn at 0.25% of body weight. Plasma was evaluated for red blood cell percentage (RBC%) in both years and serum protein (2007 only). A sugar flotation technique was used to count coccidian oocysts (Eimeria) and stomach worm eggs (Haemonchus, Ostertagia, Trichostrongylus) in feces (FEC). Prior to analysis, data for fecal parasite counts were normalized via log transformation, and geometric means were calculated on a per gram basis. In 2006, no differences (P>0.36) were found between H and W sheep for RBC% (35 vs 36 + 2.7%) or oocysts (2033 vs 1493, CV=245%). Oocysts decreased (P=0.02) from 2772 and 2218 to 861 over collection dates. In 2007, RBC% decreased (P<0.001) over the grazing season; time had no effect (P>0.28) on other measures. Neither supplement (P>0.61) nor breed type (P>0.40) affected RBC% and total serum protein. Fecal egg counts were higher (P=0.02) in supplemented (995 FEC, CV=113%) vs. unsupplemented lambs (357 FEC, CV=376%). Breed type affected oocyst (P=0.01) and FEC (P=0.12). The W lambs had higher parasite loads (2693 oocysts, CV=82%; 975 FEC, CV=208%) as compared to H (979 oocysts, CV=139%; 328 FEC, CV= 96%) and HxW (1005 oocyts, CV=162%; 644 FEC, CV=201%) lambs. In 2006, drylot lambs had a higher overall coccidian load which declined as lambs grew older. In 2007, close quarters of supplementation may have increased exposure of grazing lambs to stomach worm eggs, and hair-type breeds tended to have lower parasite counts. Results suggest genetics and diet may impact parasite load in weaned lambs.