Selection of Merino sheep for increased and decreased resistance to Haemonchus contortus: Peri-parturient effects on faecal egg counts

1992 ◽  
Vol 22 (7) ◽  
pp. 947-953 ◽  
Author(s):  
R.R. Woolaston
Keyword(s):  
Haemonchus Contortus ◽  
Merino Sheep ◽  
Faecal Egg Counts ◽  
Selection Of

Variation in resistance to haemonchosis: selection of female sheep resistant to Haemonchus contortus

1999 ◽  
Vol 73 (2) ◽  
pp. 137-142 ◽  
Author(s):  
V. Hooda ◽  
C.L. Yadav ◽  
S.S. Chaudhri ◽  
B.S. Rajpurohit
Keyword(s):  
Weight Loss ◽  
Haemonchus Contortus ◽  
Total Serum Protein ◽  
Total Serum ◽  
Serum Pepsinogen ◽  
Mean Values ◽  
Faecal Egg Counts ◽  
Female Sheep ◽  
Eosinophil Counts ◽  
Selection Of

Seventy female lambs (6–7 months old) which were exposed to natural infections of Haemonchus contortus were designated as responders or non-responders on the basis of 10 weekly cumulative faecal egg counts. Selected responder and non-responder lambs were treated with ivermectin, housed separately and 6 weeks post-housing, seven lambs from each group were given a trickle infection of Haemonchus contortus at 1000 L3 daily for 5 days per week up to 2 weeks and examined weekly for 10 weeks after first infection. Analysis of data revealed significantly lower mean faecal egg counts and non-significantly less weight loss in responder than non-responder lambs. Mean values of haemoglobin, packed cell volume, total serum protein and peripheral eosinophil counts were significantly higher in responders than non-responders. In contrast, serum pepsinogen concentration was significantly less in responders than in non-responders. At 10 weeks post-infection, there were fewer pathological lesions and significantly lower worm burdens in responders than in non-responders. These results demonstrate a distinct resistance in responders to Haemonchus contortus infection.

PSXII-2 Identification of candidate SNPs associated with high prolificacy in Romanov sheep

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 254-255
Author(s):  
Alexey V Shakhin ◽  
Arsen V Dotsev ◽  
Tatiana E Deniskova ◽  
Gottfried Brem ◽  
Natalia A Zinovieva
Keyword(s):  
Higher Education ◽  
Genetic Basis ◽  
Reference Genome ◽  
Unique Property ◽  
Candidate Snps ◽  
Merino Sheep ◽  
Sheep Breeds ◽  
Important Trait ◽  
Very High ◽  
Selection Of

Abstract Prolificacy is a very important trait in sheep. Romanov sheep, the well-known Russian sheep breed, are characterized by very high prolificacy; however, the genetic basis of this unique property of Romanov sheep is still unknown. It was reported that Ovine BMPR1B gene, located on the OAR6, is associated with prolificacy in several sheep breeds. The aim of our study was to identify candidate SNPs within BMPR1B gene, related to prolificacy. To achieve this goal, using NGS technology, we sequenced ovine BMPR1B gene in Romanov sheep (n = 6), which are characterized by high prolificacy (about 270 lambs per 100 ewes). The sequences of BMPR1B gene of Noire du Velay, Tan, Southdown and Australian Horned Merino sheep breeds as well as Asiatic mouflon (n = 1), which are characterized by significantly lower prolificacy (from 110 to 180 lambs per 100 ewes) were derived from publicly available sources and used for comparison. FST analysis performed in PLINK 1.9 program revealed 10 SNPs with values higher than 0.8. The majority of candidate SNPs under putative selection were localized in the region from 29,382,098 to 29,430,387 on OAR6 of Ovine reference genome (Oar_v3.1 (Ensembl release 98). Thus, we can suggest, that this region of the BMPR1B gene can be considered as the putative region, associated with high prolificacy of Romanov sheep. Additional studies will be needed to confirm the effect of identified candidate SNPs on prolificacy traits. The research results will be useful for artificial selection of sheep with higher prolific capacity, including the introduction of desired alleles in sheep populations using genome editing technologies. This work was supported by the Russian Ministry of Science and Higher Education No. 0445-2019-0024 and RFBR No. 20-516-56002.

Sheltering behaviour of lambing Merino sheep in relation to grass hedges and artificial windbreaks

1977 ◽  
Vol 28 (4) ◽  
pp. 691 ◽  
Author(s):  
JJ Lynch ◽  
G Alexander
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Random Distribution ◽  
Tall Grass ◽  
Merino Sheep ◽  
Selection Of

This study extends previous findings that recently shorn, lambing ewes made extensive use of the shelter provided by hedges of a tall grass (Phalaris hybrid) and that the provision of such windbreaks was associated with a reduction in lamb mortality. The study compares phalaris hedges with fences of a polyethylene garden-mesh (Sarlon; 60% porosity) and examines the effect of different spacings between Sarlon shelters. The phalaris reduced wind speed over the lee 20 m to a greater extent than Sarlon. In contrast to the marked concentration of ewes immediately adjacent to the lee of the phalaris (0–2 m), ewes were dispersed over a greater distance (0-6 m) from the lee of the Sarlon; at night about 12% more of the flock were found within 6 m of the lee of the phalaris than within the same distance of the Sarlon. In addition to the proportion of shorn ewes that were expected to be in shelter on the basis of random distribution alone, c. 35% were found within 6 m of the shelter at night, and 15% during the day regardless of whether Sarlon shelters were 20, 40 or 80 m apart. Unshorn ewes made very little use of the shelters, and lambs from shorn and unshorn ewes made more use of shelters and particularly of the phalaris than their mothers. Ewes tended to congregate at one end of the paddock regardless of wind direction and the presence of shelter, which indicated a role for strategic selection of sites for shelters. As in the previous study, lamb mortality was lower in the sheltered than in the unsheltered group, especially amongst twins.

Laboratory Selection of Haemonchus contortus for Resistance to Ivermectin

1988 ◽  
Vol 74 (4) ◽  
pp. 614 ◽  
Author(s):  
J. R. Egerton ◽  
D. Suhayda ◽  
C. H. Eary
Keyword(s):  
Haemonchus Contortus ◽  
Laboratory Selection ◽  
Selection Of

The value of production from a clipped measured area as an index of fleece weight.

1955 ◽  
Vol 6 (1) ◽  
pp. 91 ◽  
Author(s):  
FHW Morley ◽  
LW Lockart ◽  
EC Davis
Keyword(s):  
Body Weight ◽  
Correlation Coefficient ◽  
Unit Area ◽  
Multiple Correlation Coefficient ◽  
Multiple Correlation ◽  
Merino Sheep ◽  
Wool Production ◽  
Fleece Weight ◽  
Selection Of

The correlation between greasy wool production per unit area, obtained by clipping and measuring an area of about 100 cm² on the midside, and greasy fleece weight at shearing was about 0.58. Wool production from such an area over periods of 7½ or 3½ months was almost as useful as production for 11 months for predicting greasy fleece weight. The multiple correlation coefficient between greasy fleece weight as the dependant variable and production per unit area and 11-months' body weight was 0.79 in 66 rams and 0.71 in 82 ewes. The inclusion of fold score did not improve prediction appreciably. The equation W = P/110 + B1 /12 may be used to predict greasy fleece weight (lb), W, where P is production over 11 months of greasy wool (mg/cm²) and B1 is 11-months' body weight (Ib). A table of this function is included so that values may be read directly. The technique may be a useful aid to selection of Merino sheep if recording of actual fleece weights is difficult or impossible. Nevertheless it should not be regarded as more than a moderately accurate substitute for actual fleece-weighing.

Feed resource selection of Criollo goats is the result of an interaction between plant resources, condensed tannins and Haemonchus contortus infection

2018 ◽  
Vol 208 ◽  
pp. 49-55 ◽  
Author(s):  
Rafael Arturo Torres-Fajardo ◽  
Pedro Geraldo González-Pech ◽  
Javier Ventura-Cordero ◽  
Guadalupe Isabel Ortíz-Ocampo ◽  
Carlos Alfredo Sandoval-Castro ◽  
...  
Keyword(s):  
Haemonchus Contortus ◽  
Condensed Tannins ◽  
Resource Selection ◽  
Plant Resources ◽  
Selection Of
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