Effect of daily infection withOstertagia circumcinctalarvae on food intake, milk production and wool growth in sheep

Abstract

SUMMARYForty pregnant sheep were allocated to four groups and maintained indoors in individual pens on a pelleted diet. During the last 6 weeks of pregnancy and the first 6 weeks of lactation groups were infected daily with 4000 larvae of Ostertagia circumcincta or remained as controls in a cross-over design. Thus groups were either not infected (CC), infected only during pregnancy (IC), during lactation (CI) or during both pregnancy and lactation (II). Food was offered on the basis of body weight at the beginning of pregnancy and lactation. Food intake, body-weight change, faecal egg counts, plasma pepsinogen and milk production were measured weekly, wool growth and fibre diameter during 21-day periods and tensile strength of wool over the whole experimental period.Eggs were seen in faeces of only three sheep infected during pregnancy, but in all sheep infected during lactation; maximum mean values were 467 ± 144 and 222 ± 58 eggs/g fresh faeces in CI and II sheep, respectively. Pepsinogen concentrations rose after 1 week of infection during pregnancy and lactation; peak values were 868 + 57 and 1104 ± 146 m-u/l, respectively.Infection reduced food intake by 16% during lactation but had no effect during pregnancy. There were significant interactions between pregnancy and lactational treatments on intake during lactation. Infection during lactation increased bodyweight loss; mean values were 57, 40, 114 and 78 g/day for groups CC, IC, CI and II respectively. Milk production was decreased during weeks 4–6 of lactation, mean values being 1·59 and 1·32 kg/day in control and infected groups, respectively.Infection reduced wool growth and wool fibre diameter by 20 and 7%, respectively, during the final 3 weeks of infection during lactation. The staple strength of wool grown during the experiment was reduced by 14, 45 and 23% in IC, CI and II groups, respectively. Infection moved the point of greatest wool tenderness from parturition in control sheep to a time during the period of infection, particularly when infection occurred during lactation.

Epidemiology and effects of gastrointestinal nematode infection on milk productions of dairy ewes

“…The first available studies with quantitative data were carried out on experimentally infected lactating wool-meat breed ewes and all showed significant effect of nematode infections on production. Sheep infected with 28,000 larvae of T. circumcincta showed a 17 % reduction in the milk production (Leyva et al, 1982) compared to worm free controls. Likewise, Thomas & Ali (1983), who compared the milk yield of ewes orally infected weekly with 2,500 H. contortus larvae during pregnancy and lactation, reported a marked weight loss and reduction of 23 % in milk yield.…”

“…There is little information worldwide on the epidemiology (Papadopoulos et al, 2003) and risk factors (Hoste et al, 2006) of GIN in dairy sheep, even though gastrointestinal parasites are a major cause of sheep production losses in the world and Argentina (Armour, 1980;Suarez, 2007), including losses that may amount to 5 %, 24 % and 25 % for wool, meat and mortality respectively (Suarez et al, 1990) in the Semiarid Pampeana Region. A small number of investigations show the detrimental effects of nematode experimental infections in lactating ewes on both woolled and meat breeds (Leyva et al, 1982;Thomas & Ali, 1983;Sykes & Juma, 1984) and on dairy sheep systems of Europe (Fthenakis et al, 2005;Cringoli et al, 2008). Milk production systems in the Pampeana region are different of those of Europe and also predominant sheep GIN species have differences, in view of the fact that Haemonchus contortus is the most dangerous nematode for sheep production (Suarez & Busetti, 1995).…”

Genetic parameters for resistance to trichostrongylid infection in dairy sheep

“…Additionally, there are indirect losses due to a reduction in performance -E-mail: jjarrs@unileon.es (Nieuwhof and Bishop, 2005), which is in many cases caused by the subclinical effects of the infections. Several studies have shown that subclinical diseases can result in a reduction in live weight (Coop et al, 1985;Mackay et al, 1998), wool weight (Donald, 1979) and milk production (Leyva et al, 1982;Thomas and Ali, 1983).…”

Effect of supplementary feeding on the gastrointestinal strongylid eggs shedding in grazing pregnant Merino ewes

“…The increase of strongylid eggs output during late pregnancy and 6 to 8 weeks immediately post-partum caused by transient lose of resistance to helminth parasites is well documented (Leyva et al, 1982;McKellar, 1993). The periparturient rise of strongylid eggs in ewe faeces is the most important source of infection for a lamb and, as results in Figure 3 show, supplementation reduced periparturient strongylid eggs output and could diminish the risk of strongylid infection in lambs.…”