A. Kloosterman

Detection of antibodies to Cooperia ssp. and Ostertagia ssp. in calves with the enzyme linked immunosorbent assay (ELISA)

Abstract The ELISA technique was found to be very useful for the detection and monitoring of anti-Cooperia and anti-Ostertagia antibodies in calves. Six differens antigens were used; saline extracts from third- and fourth-stage larvae and from adult worms of both genera. Some degree of genus specificity was found when using L4 or adult antigens but not when L3 antigens were used. Stage-specificity could be observed for Cooperia L4 antigen for a limited period after primary single infection. These findings were supported by the results of immuno-electrophoresis.

Effect of naturally occurring nematode infections in the first and second grazing season on the growth performance of second-year cattle.

Antibody titres against Ostertagia spp., Cooperia spp. and Dictyocaulus viviparus as well as pepsinogen values, reflecting exposure to nematode infection, differed significantly among herds of second-year cattle on 87 farms. Faecal examinations revealed that gastrointestinal nematode infections were present in all herds. Similar results were found in yearling-herds on the same farms a year earlier. Liveweight of yearlings per herd deviated from -64.7 kg to +94.4 kg from an age-adjusted population mean after the second grazing season. This mean herd weight deviation was significantly related negatively to antibody titre against Ostertagia spp. (linear regression, P less than 0.05; segmented curvilinear regression, P less than 0.01) and to antibody titre against Cooperia spp. (segmented curvilinear regression, P less than 0.05), both measured in the second grazing season. Antibody titre against Ostertagia spp. measured in the first grazing season, when yearlings were calves, was significantly correlated positively to age-adjusted body weights at the end of the second grazing season. The results suggested that immunity built up during the first year had a positive effect on growth performance in the second year, but that on average the acquired immunity was insufficient to prevent reduced weight gains in the second grazing season.

Effect of anthelmintic treatment of dairy cattle on milk production related to some parameters estimating nematode infection.

On 31 farms, blood samples were taken from adult dairy cattle in September 1985, when pastured, and in November-December 1985, when stabled, to assess serum pepsinogen levels and level of nematode antibody titres. Faecal samples taken in September were examined to establish the presence of parasites by means of egg counts and larval identification. During the stabling period, dry cows were either treated with ivermectin or with a placebo in alternate sequence of expected calving date. As a result, 285 cows were treated with ivermectin while 242 cows served as controls. Anthelmintic treatment resulted in a significant increase in the 305-day milk production of 205.1 kg (P less than 0.01). Fat and protein percentages were not significantly influenced by anthelmintic treatment. There was a significant between-herd variation in nematode antibody titres and in pepsinogen values. The mean herd milk-production response to treatment correlated positively with the mean herd Ostertagia antibody titre measured in September 1985 (r = 0.364, P less than 0.05).

Breeding cattle and sheep for resistance to gastrointestinal nematodes

Gastrointestinal nematodes are an important cause of reduced production of meat, milk and wool in domestic livestock. It is generally believed that problems caused by these parasites have increased owing to the intensification of animal husbandry(1-3) of resistance to anthelmintics, current research is focussed on alternative control strategies that do not rely on anthelmintics. Here, Bram Kloosterman, Henk Parmentier and Harm Ploeger review work on the genetic resistance of domestic ruminants to these nematodes and discuss the practicality of breeding programmes.

Genetic variation among calves in resistance to nematode parasites

Abstract Dutch Friesian male calves, which received a dose of 100 000 Cooperia spp. larvae at an age of 3 months, displayed a great variability in reaction, measured by number and length of worms, egg output, serum antibodies and liveweight gain. In an experiment with half-sib groups from randomly chosen sires, only the antibody response was significantly different between sire-groups. In a further experiment with half-sibs from two selected sires, egg output, worm numbers, worm length and antibody response differed. A third trial with half-sib groups of the same two sires was carried out under natural conditions of grazing. It is concluded that, within this breed, genetical variation exists in resistance to Cooperia spp.

Milk yield increase after anthelmintic treatment of dairy cattle related to some parameters estimating helminth infection.

On 81 farms blood samples were taken from adult dairy cattle, on pasture in October 1986 and after stabling in December 1986, to measure antibody titres against the nematodes Dictyocaulus viviparus, Cooperia spp. and Ostertagia spp., and the trematode Fasciola hepatica, and serum pepsinogen values. Faecal samples, collected in October, were examined to confirm the presence of parasites by means of egg counts and larval identifications. From December until the end of the stabling period, dry cows were either treated with albendazole or left untreated in alternate sequence of calving date. Treated cows produced 132.9 kg milk per cow per lactation more than untreated cows (P less than 0.01). Fat and protein percentage were not significantly influenced by anthelmintic treatment. The mean herd milk yield response to treatment varied from -889 to +1231 kg milk per cow per lactation. There was a significant between-herd variation in antibody titres against nematodes and in pepsinogen values. However no significant correlations between these parameters and the mean herd milk yield response to treatment were found.

Negative interactions between Ostertagia ostertagi and Cooperia oncophora in calves

The interactions between Ostertagia ostertagi and Cooperia oncophora were studied in calves by concurrent and sequential infections. A reciprocal negative interaction between the 2 species was found in sequential, but not in concurrent infections. This result was supported by the finding of serological cross-reactions. It is suggested that the negative interaction is immunologically mediated. The depression of weight gain found after infection was similar for O. ostertagi- and C. oncophora-infected calves.

The value of bulk milk ELISA Ostertagia antibody titres as indicators of milk production response to anthelmintic treatment in the dry period

An experiment was done to study whether estimation of the herd infection level, by assessing Ostertagia antibodies in bulk milk samples can serve to predict the effect of anthelmintic treatment on milk production. Bulk milk samples were collected from 134 farms at monthly intervals on three occasions prior to the start of the study. The ELISA titres to Ostertagia found in October at the end of the grazing season served as a basis to select 16 and 18 farms as having high and low levels of parasitism respectively. Heifers and cows within each herd were ranked by expected calving date, paired and randomly allocated to be treated with ivermectin or a placebo. Records of milk production and composition were collected for all the trial animals. The response to treatment expressed as the 305 day corrected milk yield of anthelmintic treated animals minus that of placebo treated animals was not statistically significant and amounted to 78 kg for multiparous cows and 124 kg for heifers. For cows as well as heifers the response to treatment was larger in the high antibody level herds than in low antibody level herds, but these differences also lacked statistical significance.

Gastrointestinal nematode infections and weight gain in dairy replacement stock: first-year calves

For the evaluation of control strategies against, and economic impact of gastrointestinal nematode infection, the quantitative relationship between level of exposure to infection and growth performance is important. Available data in the literature are summarised. Based on questions derived from earlier work concerning the relationships between infection, growth performance and acquired immunity during the entire rearing period, two experiments were set up. In these experiments, groups of calves were exposed to different levels and patterns of infection with Ostertagia ostertagi and Cooperia oncophora. The experimental design simulated the stereotypic pattern of herbage infestation under conditions of set-stocking. A significant negative linear relationship between the level of exposure and growth performance was found (P < 0.001). The time sequences observed for body weight changes in response to infection and the magnitudes of the effects of infection on weight gain in both experiments suggested a good predictability of the relationship between infection and growth performance. By comparison, it is also suggested that in the Netherlands parasite control is excessive in the first grazing season. A more limited use of anthelmintic treatments is proposed.

Age resistance in calves to Ostertagia ostertagi and Cooperia oncophora.

Calves were infected repeatedly during a period of 6 weeks with Ostertagia ostertagi and Cooperia oncophora, at an age of 3, 6 or 9 months. The inoculations were performed during three periods, February-March, May-June and August-September, to account for possible seasonal effects or effects of larval batches. Observations were done on faecal egg output, antibody titres and weight gains. Calves were slaughtered for post mortem examinations 9 weeks after the start of infections. The influence of age on worm populations and egg output was significant for C. oncophora but not for O. ostertagi. The effect of season or larval batch on worm populations was significant for O. ostertagi but not for C. oncophora. The correlations between worm numbers and several other parameters found for Cooperia were strongly indicative of a process of worm expulsion taking place at the stage of infection (9 weeks after the start of infections) when post mortem examinations were done. Such correlations were absent for Ostertagia. It is concluded that within the range of ages examined here (the range to which first season grazing calves belong), there is no influence of age on Ostertagia populations but a clear effect of age on Cooperia. This difference strongly influences the total faecal egg output of grazing calves and its interpretation.