Trichostrongylosis and wool growth. 2. The wool growth response of infected sheep to parenteral and duodenal cystine and cysteine supplementation

Abstract

Two experiments are reported. In experiment 1, light infections with the intestinal nematode Trichostrongylus colubriformis reduced wool growth of sheep by 42 per cent compared with pair-fed controls. There was no significant difference in wool growth between those sheep given a cystine supplement as an intraperitoneal pellet and those given a daily intra-duodenal injection of cystine, although cystine was poorly absorbed from the peritoneal cavity. In experiment 2, fifteen sheep were fed a maintenance ration and their wool growth rates defined. When six of the sheep were given a daily intra-duodenal drip containing 2 g cysteine hydrochloride, and six sheep were given the same drip intravenously, their wool growth rate increased by a mean of 33 per cent compared with the wool growth of the three untreated sheep, irrespective of the route of administration of the cysteine. Three sheep in each group of six were then lightly infected with Trichostrongylus colubriformis and the wool production of all sheep was measured in the presence and absence of the daily cysteine supplement via the two routes. The infection depressed wool growth, but did not influence the wool growth response to either route of cysteine supplementation. It was concluded that the reduced wool growth induced by trichostrongylosis could not be attributed to malabsorption of cysteine. Evidence was obtained that sheep resistant to Trichostrongylus colubriformis produced less wool when subjected to a larval challenge.

Protein supply influences the nutritional penalty associated with the development of immunity in lambs infected with Trichostrongylus colubriformis

“…Tentative support for this hypothesis can be obtained from the greater reductions in both muscle deposition and wool production in L-R animals in the present work and amelioration of the reduction in wool growth in animals infected with T. colubriformis following cysteine supplementation (Barger et al, 1973). Clearly, further elucidation of the potential trade-off between animal performance and IgA production is required before strong conclusions can be drawn.…”

Metabolic consequences of intestinal parasitism

“…Interestingly, Barger et al (1973) observed that sheep resistant to T. colubriformis produce 17-18% less wool when subjected to a larval challenge; wool is rich in cysteine (10% of the total amino acid mixture, approximately fourfold higher than that in most other body components; see MacRae & Lobley, 1991). Also, in the experiments of Kimambo et al (1988a), once the lambs had developed resistance they started to regain weight, but, although they received the same quantity of feed daily as the pair-fed controls which were several kilograms heavier, the resistant animals exhibited no catch-up growth, implying some kind of nutritional penalty associated with their immunological status.…”

The effects of natural trichostrongylid larval challenge on 2-year-old Freisian steers

“…Barger et al (1973) and Barger & Southcott (1975) obtained up to 18070 reduction in wool growth in sheep resistant to Trichostrongylus colubriformis when such sheep were exposed for further infection either indoors or on pasture. Bryan (1976) attributed an increase in weight gain of beef calves to the reduced stimulation of the host immune response as a consequence of a reduction in larval nematode challenge.…”

“…Some overseas studies, however, have associated production losses in older, resistant animals, with larval challenge per se and the apparent stimulation of the host immune response Anderson 1972Anderson , 1973Barger et al 1973;Barger & Southcott 1975;Reid & Armour 1975;Bryan 1976;Armour et al 1979;Yakoob et al 1983;Brunsdon et al 1986). As most incoming parasties do not establish and grow in the resistant host, the observed production losses have been attributed to allergic-type reactions of the host in response to larval challenge.…”