Trichostrongyle worm infection in cattle: Ostertagiasis and concurrent infections in dairy calves: Seasonal patterns of occurrence, pathology and diagnosis

The potential role of pasture management in the control of trichostrongyle worm infection in calves with observations on the diagnostic value of plasma pepsinogen determinations

“…In earlier papers, the writer (Brunsdon, 1969(Brunsdon, , 1971) summarized available evidence regarding the value of plasma pepsinogen dete,rminations in the diagnosis of disease caused by abomasal, trichostrongyle infections in cattle. The results (Brunsdon.…”

“…In a recent Wallaceville study (Brunsdon, 1972), using previously worm~free "tracer" calves it was found that infections of up to approximately 330,000 worms were acquired in a fortnight's grazing. As the principal lesions of ostertagiasis occur 18 to 21 days post-infection when the adult worms emerge from the, abomasal mucosa (Jarrett, 1966), it will be appreciated that, at times of heavy pasture infestation, considerable production losses can result from infection acquired in the interval betwe.en monthlv drenches.…”

“…The mean worm count for the seven Group 1 animals, slaughtered between September 2 and September 16, 1971, was as follows: Ostertagia spp., 181,000 (62% to 95 % in the early 4th larval stage); Trichostrongylus axei,18,000; Cooperia spp., 9,000 (0% to 50% in early 4th larval stage). Details of these counts were published separately (Brunsdon, 1972). DISCUSSION In the British Isles, Michel (1969) has shown that, in the case of Ostertagia ostertagi, the time which elapses between contamination of pasture and the, appearance of infective larvae on pasture is long for pastures contaminated in spring and that this interval decreases as the season advances.…”

“…(1) Although, as pointed out previously (Brunsdon, 1969(Brunsdon, , 1971, plasma pepsinogen values provide an indication of the degree of abomasal damage per se, which in turn is directly related to the level of abomasal infection, the pathogenici ty of a particular level of infection will vary according to the age, size and condition of the host.…”

“…The worm counting technique was as described previously (Brunsdon, 1969) except that a 350 mesh sieve (mesh aperture 45 r.L) was used. As part of the worm counting procedure, peptic digests (Herlich, 1956) were carried out on all abomasa.…”