Heligmosomoides bakeri: a model for exploring the biology and genetics of resistance to chronic gastrointestinal nematode infections

SUMMARYThe intestinal nematodeHeligmosomoides bakerihas undergone 2 name changes during the last 4 decades. Originally, the name conferred on the organism in the early 20th century wasNematospiroides dubius, but this was dropped in favour ofHeligmosomoides polygyrus, and then more recentlyH. bakeri, to distinguish it from a closely related parasite commonly found in wood mice in Europe.H. bakeritypically causes long-lasting infections in mice and in this respect it has been an invaluable laboratory model of chronic intestinal nematode infections. Resistance toH. bakeriis a dominant trait and is controlled by genes both within and outside the MHC. More recently, a significant QTL has been identified on chromosome 1, although the identity of the underlying genes is not yet known. Other QTL for resistance traits and for the accompanying immune responses were also defined, indicating that resistance toH. bakeriis a highly polygenic phenomenon. Hence marker-assisted breeding programmes aiming to improve resistance to GI nematodes in breeds of domestic livestock will need to be highly selective, focussing on genes that confer the greatest proportion of overall genetic resistance, whilst leaving livestock well-equipped genetically to cope with other types of pathogens and preserving important production traits.

Download Full-text

Genetic resistance of different genotypes of sheep to natural infections with gastro-intestinal nematodes

Animal Science ◽

10.1017/s1357729800015599 ◽

1997 ◽

Vol 64 (1) ◽

pp. 97-104 ◽

Cited By ~ 6

Author(s):

Endang Romjali ◽

V. S. Pandey ◽

R. M. Gatenby ◽

M. Doloksaribu ◽

H. Sakul ◽

...

Keyword(s):

First Generation ◽

Genetic Resistance ◽

The Body ◽

Birth Season ◽

Weaning Weight ◽

Intestinal Nematode ◽

Faecal Samples ◽

Breeding Programmes ◽

Nematode Eggs ◽

Mcmaster Method

AbstractDuring a 3-year period, from April 1991 to December 1993, in a flock with four lambing periods annually, faecal samples from lambs at weaning at the age of 3 months (no. = 1756), were examined for gastro-intestinal nematode eggs by the McMaster method. Faecal samples were also examined at the age of 9 (no. = 170), 12 (no. = 157), 15 (no. = 253) and 18 (no. = 85) months from the females only. From June to December 1993 packed cell volume (PCV) was also examined from lambs at weaning. Seven genotypes were used in this study.The faecal egg counts were affected by genotype, birth season, type of birth and rearing, sex and age. First generation cross of Sumatra × Barbados Blackbelly had lowest eggs per g of faeces (EPG) followed by Sumatra, St Croix, Sumatra × St Croix Fl and F2 and Sumatra × Java Fat tail. Lambs born in February-March when rainfall was low had lower EPG (V < 0·05) than those born in May-June or August-September. The EPG of lambs born and reared singly were significantly lower (P < 0·001) than those born twin, triplet or quadruplet. Female lambs had lower EPG than male lambs (P < 0·001). The EPG of lambs at 3 months were higher than at 9, 12, 15 or 18 months (P < 0·001).PCV was affected by genotype, sex, type of birth and rearing and season of birth. There was a positive correlation between PCV and weaning weight of lambs and a negative correlation between EPG and weaning weight. These results show that the crosses of St Croix and Barbados Blackbelly with local Sumatra sheep are at least as resistant or more resistant to gastro-intestinal nematodes than pure Sumatra breed and therefore these breeds can be used in cross breeding programmes to improve the body size of local Sumatra sheep.

Download Full-text

Genetic Basis of Mastitis Resistance in Dairy Cattle – A Review / Podstawy Genetyczne Odporności Krów Mlecznych Na Zapalenie Wymienia – Artykuł Przeglądowy

Annals of Animal Science ◽

10.2478/aoas-2013-0043 ◽

2013 ◽

Vol 13 (4) ◽

pp. 663-673 ◽

Cited By ~ 17

Author(s):

Grażyna Sender ◽

Agnieszka Korwin-Kossakowska ◽

Adrianna Pawlik ◽

Karima Galal Abdel Hameed ◽

Jolanta Oprządek

Keyword(s):

Dairy Cattle ◽

Association Studies ◽

Genetic Resistance ◽

Clinical Mastitis ◽

Future Research ◽

Complex Nature ◽

Candidate Gene Approach ◽

Genome Wide Association Studies ◽

Polygenic Control ◽

Breeding Programmes

Abstract Mastitis is one of the most important mammary gland diseases impacting lactating animals. Resistance to this disease could be improved by breeding. There are several selection methods for mastitis resistance. To improve the natural genetic resistance of cows in succeeding generations, current breeding programmes use somatic cell count and clinical mastitis cases as resistance traits. However, these methods of selection have met with limited success. This is partly due to the complex nature of the disease. The limited progress in improving udder health by conventional selection procedures requires applying information on molecular markers of mastitis susceptibility in marker-assisted selection schemes. Mastitis is under polygenic control, so there are many genes that control this trait in many loci. This review briefly describes genome-wide association studies which have been carried out to identify quantitative trait loci associated with mastitis resistance in dairy cattle worldwide. It also characterizes the candidate gene approach focus on identifying genes that are strong candidates for the mastitis resistance trait. In the conclusion of the paper we focus our attention on future research which should be conducted in the field of the resistance to mastitis.

Download Full-text

Selective Diversification of Aquaculture Stocks: A Proposal for Economically Sustainable Genetic Conservation

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f91-313 ◽

1991 ◽

Vol 48 (S1) ◽

pp. 148-154 ◽

Cited By ~ 12

Author(s):

R. W. Doyle ◽

N. L. Shackel ◽

Z. Basiao ◽

S. Uraiwan ◽

T. Matricia ◽

...

Keyword(s):

Genetic Diversity ◽

National Level ◽

Economic Benefits ◽

Conservation Strategy ◽

Environment Interaction ◽

Production Traits ◽

Local Environments ◽

Genotype Frequencies ◽

Genetic Impact ◽

Breeding Programmes

The genetic diversity of aquaculture stocks can be maintained, and their genetic impact on wild stocks minimized, by breeding programmes that deliberately generate genetic diversity. Current animal breeding practices are likely to reduce the diversity of domestic stocks if they are extended to aquaculture. It is proposed that national breeding programmes for aquaculture should, instead, try to develop numerous breeds specially adapted to local environments and aquaculture systems. An economic model is presented of decision-making by individual farmers who, in choosing which breed to produce, determine the "fitness" of the breeds in a meta-population that includes all breeds. As long as strong genotype-environment interaction for production traits is maintained by artificial selection, the economic self-interest of farmers should ensure the stability of genetic polymorphisms among breeds. Genetic variation would be conserved (in the among-breed component of genetic diversity) but not the primordial distribution of gene and genotype frequencies. Economic benefits to farmers, plus a high return on investment at the national or supra-national level, makes breed diversification an attractive conservation strategy even though it is admittedly a compromise from a purely genetic viewpoint.

Download Full-text

Effect of pasture species on internal parasites of lambs

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.1996.58.2217 ◽

1996 ◽

pp. 59-62 ◽

Cited By ~ 1

Author(s):

T.L. Knight ◽

R.A. Moss ◽

T.J. Fraser ◽

J.S. Rowarth ◽

R.N. Burton

Keyword(s):

White Clover ◽

Tall Fescue ◽

Festuca Arundinacea ◽

Plantago Lanceolata ◽

Gastrointestinal Nematode ◽

Gastrointestinal Nematodes ◽

Grass Species ◽

Adult Nematode ◽

Intestinal Nematode ◽

Nematode Parasites

Increasing resistance of gastro-intestinal nematode parasites to anthelmintics and consumer resistance to the possibility of residues in animal products have prompted research on the effect of pasture species on nematodes and animal performance. Lambs (either infected with high rates of gastrointestinal nematodes or maintained nematode-free) were grazed on pure swards of chicory, high- or low-endophyte ryegrass, cocksfoot, tall fescue, lucerne, lotus, white clover or plantain. Infected lambs that grazed chicory had lower faecal egg counts and adult nematode populations, and higher carcass weights, than lambs grazed on plantain or the grass species; lambs that grazed legumes generally had intermediate counts, populations and weights. When kept parasite-free, carcass weights were up to 48% greater than in the nematodeinfected treatments. On farmlets run over 3 years, substituting 30% of the ryegrass area with lucerne or replacing the ryegrass with a multi-species mix consisting predominantly of bromes, tall fescue, phalaris, timothy and red and white clover, had no effect on gastrointestinal nematode larvae, lamb faecal worm egg or adult nematode numbers. It is concluded that a diet of pure chicory affects internal parasite populations but the small proportion included in the farmlet studies had no effect. Keywords: Cichorium intybus, Dactylis glomerota, Festuca arundinacea, gastro-intestinal nematodes, lambs, Lolium perenne, Lotus corniculatus, Medicago sativa, pasture species, Plantago lanceolata, Trifolium repens

Download Full-text

Are Scottish Blackface ewes more resistant to nematode parasite infection than Greyface ewes?

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200028672 ◽

2009 ◽

Vol 2009 ◽

pp. 28-28

Author(s):

A Kidane ◽

J G M Houdijk ◽

B J Tolkamp ◽

S Athanasiadou ◽

I Kyriazakis

Keyword(s):

Genetic Resistance ◽

Gastrointestinal Nematode ◽

Parasite Infection ◽

Nematode Parasite ◽

Nutrient Demand ◽

Nematode Parasites ◽

Breed Differences ◽

Lower Extent ◽

Ad Libitum ◽

Per Se

The extent of periparturient relaxation of immunity (PPRI) to gastrointestinal nematode parasites is sensitive to metabolisable protein (MP) scarcity but also varies between breeds of sheep (Houdijk, 2008). For example, under ad libitum feeding, Scottish Blackface ewes had a lower extent of PPRI than Greyface ewes (Zaralis et al., 2008). Such between-breed variation in PPRI may not necessarily be associated with genetic resistance per se but could arise from a higher nutrient demand of the more productive Greyface ewes (Houdijk, 2008). This experiment was designed to test the hypothesis that if the extent of PPRI has only a nutritional basis, then the sensitivity of PPRI to MP scarcity will not differ between the breeds when MP feeding is adjusted for between-breed differences in MP demand.

Download Full-text

Current and future developments in dairy cattle breeding: a research viewpoint

BSAP Occasional Publication ◽

10.1017/s0263967x00031736 ◽

1995 ◽

Vol 19 ◽

pp. 1-7

Author(s):

W. G. Hill ◽

S. Brotherstone ◽

P. M. Visscher

Keyword(s):

Dairy Cattle ◽

Reproductive Technologies ◽

Production Traits ◽

Rapid Improvement ◽

Cattle Breeding ◽

Evaluation Procedures ◽

Selection Decisions ◽

Dairy Cattle Breeding ◽

Breeding Programmes ◽

Selection Intensities

AbstractRates of genetic improvement in dairy cattle breeding programmes have increased substantially in the last decade, not only in Europe where there has been substantial immigration of North American stock. More accurate statistical evaluation procedures, including the use of best linear unbiased prediction (BLUP) with the animal model, have been introduced; higher selection intensities have been achieved, particularly on production traits, through better organized and focused schemes; and developments in multiple ovulation and embryo transfer (MOET) have been both a stimulus and to some extent a cause. Continued rapid improvement can be expected as research and development enables more accurate and timely use to be made of recording data, because there is evidence that heritability values for milk production are rising, perhaps because of better cow management, and as competition among breeders internationally increases. There are a number of consequent challenges to geneticists and breeders. Attention will have to be given to maintaining the fitness of very high producing animals by recording health, fertility, longevity and parlour traits, and using the results of research to give them appropriate weight in selection decisions. Developments in molecular methods and in reproductive technologies present new opportunities, but are unlikely to do more for some time than complement progress from conventional selection on the important production traits.

Download Full-text

Genetic resistance to two Marek's disease viruses and its relationship to production traits in chickens

Canadian Journal of Animal Science ◽

10.4141/cjas92-028 ◽

1992 ◽

Vol 72 (2) ◽

pp. 213-225 ◽

Cited By ~ 4

Author(s):

H. Ameli ◽

J. S. Gavora ◽

R. W. Fairfull ◽

J. L. Spencer

Keyword(s):

Egg Production ◽

Genetic Correlations ◽

Genetic Resistance ◽

Total Mortality ◽

Marek's Disease ◽

Production Test ◽

Production Traits ◽

Marek’S Disease ◽

Genetic Groups ◽

Challenge Tests

Genetic variability of resistance to Marek's Disease (MD), and relationships between MD incidence and egg production traits were studied in 23 genetic groups of experimental and commercial meat and egg chickens. In the challenge tests, chickens were injected with either moderately virulent BC-1 MD virus (BC-1) or highly virulent RB-1B MD virus (RB-1B). In the 497-d egg-production test, sisters of challenged birds were vaccinated for MD on the day of hatch and there were no outbreaks of MD. Heritabilities for MD incidence, MD mortality, and total mortality in the challenge tests, based on data from three unselected control strains of Leghorns were generally low (0.06, 0.13 and 0.20) with BC-1. With RB-1B, the heritability estimates were significantly (P <.05) higher (0.62, 1.00 and 0.96). Intraclass correlations, based on variation between and within the genetic groups were also higher with RB-1B. In the test with BC-1 there were deaths from an early mortality syndrome (EMS) prior to development of MD. Losses from EMS in Leghorns were highest in 2 genetic groups most resistant to MD. Based on genetic group means, correlations between MD incidence and egg production and egg weight were high and negative. In contrast the correlations between MD incidence, age at first egg, total blood spots, and egg specific gravity tended to be positive. No consistent relationships were found with adult body weight. Key words: Marek's disease, genetic resistance, heritability, genetic correlations, production traits, chickens

Download Full-text