<i>Trichostrongylus colubriformis</i> and <i> Haemonchus contortus</i> infections in light bodyweight Merino lambs

McClure, S.J.; Emery, D.L.

doi:10.1111/j.1751-0813.2007.00221.x

Cited by 8 publications

(4 citation statements)

References 27 publications

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“…The ability to exclude nematodes from tissues is acquired during the second phase and, in 3-4 month, old, previously naïve 30 kg lambs this occurs after about 8 weeks of infection (Symons et al, 1981;Sykes & Coop, 1976;Kimambo et al, 1988) and, as indicated earlier may be dependent on body maturity (McLure & Emery, 2007).…”

Section: The Immune Response and Productivitymentioning

confidence: 98%

Host immune responses to nematodes: benefit or cost? Implications for future development of sustainable methods of control

Sykes

2010

R. Bras. Zootec.

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The nutritional and production costs associated with the development of a competent immune response against nematode parasites is described, based on data from sheep. Anorexia and changes in metabolism are considered to be driven by the host immune response itself and the question is raised about the wisdom of seeking to strengthen immune responses by genetic selection. Several phases of the immune response are identified with different implications for loss of productivity and opportunity for moderation of immune responses and production losses by nutrition. Many animals are able to manage nematode infections with little loss of productivity. In an era when attempts are being made to reduce anthelmintic use and create refugia to reduce the rate of development of drench resistance, treatments based on individual animal performance relative to production targets set by assessment of the prevailing nutritional environment will become more common. These developments, have already occurred in relation to the haematophagic nematodes, for example the "Famacha" technique. Computer-aided weighing and drafting has potential for use with the less pathogenic nematodes prevalent in temperate regions though we need to know more about the pathophysiology and nutritional costs of infections with Nematodirus spp.

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Section: The Immune Response and Productivitymentioning

confidence: 98%

Host immune responses to nematodes: benefit or cost? Implications for future development of sustainable methods of control

Sykes

2010

R. Bras. Zootec.

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“…What is less clear is whether this is an effect of physical age alone or whether it is influenced by stage of maturity and thus an effect of live weight. In one of the few studies to report on the importance of live weight on development of immunity, a minimum weight of 23 kg was required in Merino lambs at the start of infection with T. colubriformis to successfully reduce worm burdens during a secondary infection . Ultimately, age and weight in a growing animal are confounded and it is plausible that age effects on development of immunity reflects the importance of live weight or the stage of their growth trajectory.…”

Section: Factors Influencing the Development Of Immunitymentioning

confidence: 99%

“…A summary of reported mean live weights at the time immunity developed from sources in the literature and estimates of the expected mature weight for each breed are given in Table . In the previously mentioned studies involving a truncated T. colubriformis infection of Merino lambs , an initial live weight of 23 kg was required for lambs to have developed the capacity to limit the size of the parasite burden during a secondary infection, representing an expected relative maturity of 42%. Concurrent decline in FEC and resumption of normal growth indicating immune development and transition to the expression phase in Coopworth lambs has been observed during infection with T. circumcincta or T. colubriformis at relative maturities of 49%, 46% and 44% .…”

Section: Importance Of Relative Maturitymentioning

confidence: 99%

Relative maturity and the development of immunity to gastrointestinal nematodes in sheep: an overlooked paradigm?

Greer

Hamie

2016

Parasite Immunology

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Sheep display considerable variation in both the timing and magnitude of development of immunity to gastrointestinal nematodes (GIN). Onset of immunity is dependent on a number of factors, including antigenic stimulus, nutrition supply, age and size of the animals, the latter of which are confounded. Here, we review the factors associated with the development of immunity to GIN in sheep, particularly in the context of the role that relative maturity may have through applying the rules of genetic size scaling based on examples from published literature. Comparing animals based on their metabolic age, rather than chronological age, may provide an explanation for the timing of immune development and may reduce the variation in immune development that frequently is observed both between and within breeds. Further, this approach may help explain the phenotypic differences in animal performance between animals of varying immunological capacity to GIN through influences on mature body weight. As such, when considering factors influencing immune development to GIN, physiological age or relative maturity may be considered an overlooked paradigm. We propose it may be worthwhile to consider metabolic age when comparing the immune competence of animals to ensure the subjects are at an analogous stage of physiological development.

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“…In the case of endoparasitism of sheep, a considerable body of work has investigated the interactions between nutrition and resistance, concentrating largely on proteins 7 , 8 , 9 , 10 . Two studies on the effect of age, liveweight and diet on susceptibility of lambs to the gastrointestinal nematode Trichostrongylus ( T. ) colubriformis demonstrated that lambs weighing less than 23 kg at the time of first exposure and thus lacking body reserves have an impaired ability to develop protective gut immunity against a secondary infection 11 unless fed a diet high in total (19.5%) and bypass protein and energy (9.9 MJ metabolizable energy (ME) per kg dry matter) 12 . These studies also found that diets deficient in one of a number of nutrients, including readily available carbohydrate (raCHO), resulted in a reduced (six‐ to ninefold) or retarded resistance of lambs against a secondary infection.…”

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confidence: 99%

Dietary modulation of the mucosal immune response to a parasite

McClure

2008

Immunol Cell Biol

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This study investigated the hypothesis that dietary deficiency of readily available carbohydrate (raCHO) modifies the immune response of lambs to the gastrointestinal nematode Trichostrongylus colubriformis. Sixty helminthologically naive Merino lambs were fed throughout the experiment diets containing three levels of raCHO that provided adequate, moderate or low intakes according to recommended standards and were given primary or both primary and secondary infections of T. colubriformis. A further 20 uninfected lambs received the low diet for 9 weeks, after which they were returned to the standard diet. Immune status was assessed by the measurement of plasma and jejunal antibody concentrations and blood and jejunal cell numbers and function. Diets low in carbohydrate resulted in a failure of the lambs to gain weight and decreases in plasma glucose concentration, blood lymphocytes expressing CD8 or Tcrcd, monocytes, eosinophils, platelets and red blood cells, jejunal and plasma antibody concentrations, lymphocyte proliferation to worm antigen and numbers of jejunal CD8 + and Tcrdc + lymphocytes, eosinophils and CD1b + dendritic cells. Thus, a low dietary concentration of raCHOs impaired the constitutive availability of lymphocytes and antigen-presenting cells, and the cellular and humoral immunological responses. A hypothesis is suggested for the mechanism and for the possible wider implications. In addition to determining the precipitating cause, the control and prevention of many diseases requires the understanding of the predisposing factors and the mechanism by which they allow the precipitating causes to act. Host resistance and immunity are pivotal to infectious disease prevention, and many chronic diseases involve immune dysfunction, irrespective of the precipitating cause. 1,2 A major predisposing cause of immune dysfunction is inadequate or unbalanced nutrient intake. There is a very basic expectation that adequate nutritional status is necessary for resistance of animals, including humans, to infectious diseases. 3,4 However, in practice it is largely ignored, possibly because within the umbrella of malnutrition, the specific nutrients and their pathogenesis are inadequately defined. Malnutrition deserves attention for at least two reasons. It occurs with a significant frequency in both livestock and human populations, and in the latter in both low and high socio-economic conditions. 5,6 Also, malnutrition is a factor that, if adequately understood, is practically and economically avoidable.In the case of endoparasitism of sheep, a considerable body of work has investigated the interactions between nutrition and resistance, concentrating largely on proteins. [7][8][9][10] Two studies on the effect of age, liveweight and diet on susceptibility of lambs to the gastrointestinal nematode Trichostrongylus (T.) colubriformis demonstrated that lambs weighing less than 23 kg at the time of first exposure and thus lacking body reserves have an impaired ability to develop protective gut immunity against a second...

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Trichostrongylus colubriformis and Haemonchus contortus infections in light bodyweight Merino lambs

Abstract: If the goal is to ensure that lambs develop immunity before weaning, then every endeavour should be made to achieve the combination of critical bodyweight and exposure to moderate levels of nematode infection as soon as possible.

Cited by 8 publications

References 27 publications

Host immune responses to nematodes: benefit or cost? Implications for future development of sustainable methods of control

Host immune responses to nematodes: benefit or cost? Implications for future development of sustainable methods of control

Relative maturity and the development of immunity to gastrointestinal nematodes in sheep: an overlooked paradigm?

Dietary modulation of the mucosal immune response to a parasite

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