Influence of repeated regrouping on reproduction in gilts.

It is generally assumed that stress around oestrus and during early pregnancy reduces reproductive performance of pigs. In our experiment, late prepuberal gilts (age at arrival 225+/-6 days) were housed in groups of four. Stress treatment consisted of once weekly regrouping and twice weekly feed competition of the 28 Stress gilts during 6 consecutive weeks, starting 13 days after arrival. Control gilts (n=28) were not treated. During the 0.5-1.5h after regroupings, Stress animals fought consistently more than the Control animals; up to 13 of the Stress animals fought for at most 60% of the time compared to one Control animal fighting for at most 3.3% of the time. The day before first regrouping, gilts had on average 4.0+/-0.9 skin scratches. By week 6, this number had reduced to 2.1+/-1.0 in Control, but remained 4.0+/-1.3 in Stress gilts (P<0.05). In the afternoon after regroupings, skin scratches increased up to 6.3+/-1.6 in the Stress gilts. Saliva cortisol in the afternoon before regrouping did not differ between weeks 1, 3 and 6, nor did it differ between Stress and Control. In Stress gilts, saliva cortisol was increased in the afternoon of first regrouping, in Batch 2 only (from 1.8+/-0.4 to 4.1+/-0.9 ng/ml; P<0.05). Animals showing a second oestrus within 5 weeks after arrival were inseminated. Duration of second oestrus of these animals was 2.48+/-0.66 days in the Stress gilts (n=24) and 2.21+/-0.58 days in the Control gilts (n=22; P>0.10). At Day 35 after insemination, pregnancy rate was 100% in both groups. Ovulation rate and number of total and vital fetuses was similar (P>0.10). The Stress treatment during a 6-week period around insemination consistently resulted in fighting but did not result in long term effects on cortisol levels and did not impair reproductive performance.

Low molecular weight Cooperia oncophora antigens. Potential to discriminate between susceptible and resistant calves after infection.

The recognition of low molecular weight proteins by sera obtained during a single oral (primary) infection with 100,000 3rd-stage Cooperia oncophora larvae was studied in calves. Three groups of 6 or 7 calves were selected based on different egg excretion patterns. SDS-gel electrophoresis of adult Cooperia antigen under reducing conditions, followed by Western blotting, revealed that resistance of individual calves to C. oncophora might be related with antibody responses (42 days post infection) against at least 2 protein fragments (14-16 kDa and 27 kDa). The 14-16-kDa protein complex was bound, to some extent, by individual sera from all calves. The intensity of staining was negatively correlated with egg excretion on Day 42 p.i. Calves with high egg counts on Day 21 p.i. either did not or only weakly recognized the 27-kDa band. It has to be established whether the 14-16 kDa (or recombinant 14.2 kDa) provides a tool for immunodiagnostics and whether the 27-kDa fragment can help further unravel immune-mediated resistance to Cooperia.

Recognition of low molecular weight Cooperia oncophora antigens after primary and trickle infection of calves with third-stage infective larvae.

Recognition of low molecular protein fragments of adult Cooperia oncophora of calves was studied using sera obtained after a single oral (primary) infection with 100,000 infective 3rd-stage C. oncophora larvae, and after a 10-week period of trickle infection with moderate doses of these larvae. SDS-gel electrophoresis under reducing conditions, followed by western blotting, revealed that a complex of 14-16 kDa protein fragments, a 27 kDa and a 31.6 kDa band of Cooperia oncophora adult antigen were recognized by sera from calves both after primary and trickle infection. A 19 kDa and 30 kDa protein fragment were additionally bound by sera from calves after trickle infection. The data suggest that the systemic humoral immune response of calves to Cooperia oncophora after trickle infection is more pronounced (14-16, 27, 31.6 kDa) and extended (19, 30 kDa) than after primary infection with Cooperia.

Production of dairy replacement stock in relation to level of exposure to gastrointestinal nematode infection in the first grazing season: second-year calves and heifers.

In two experiments, groups of calves which had been exposed to different levels and patterns of infection with Ostertagia and Cooperia spp. in a simulated first grazing season (FGS), were followed throughout a natural second grazing season (SGS). Milk yields in the subsequent first lactation period were also recorded. The results suggest that although there had been differences in immune status among groups, which had been infected in the FGS, prior to the SGS, weight gain among these groups was not significantly different during the SGS. Apparently, resistance to the pathogenic effects of reinfection had developed more strongly and at lower levels of exposure to infection than resistance against establishment of larvae as shown after an experimental challenge. The groups of calves not infected during the FGS did gain less than all other groups during the SGS. Further, infection-induced differences in weight gain among the infected groups in the FGS appeared to be permanent, at least up to the end of the SGS. Finally, first lactation yield was positively correlated with body weight at calving. On average, approximately 10 kg less milk was produced for each kg of lower body weight at calving. With respect to the implications for preventive control strategies in the FGS, it is suggested that parasite control should not be applied beyond a level at which weight gain reduction is prevented.

Low molecular weight Cooperia oncophora antigens: characterization and humoral immune responses in calves mono-infected with 100,000 infective larvae.

Characteristics of the humoral immune response of Cooperia oncophora-infected calves to low molecular weight antigens of C. oncophora were studied. Immunoblotting with sera obtained from calves 6 weeks after a single oral infection with 100,000 third-stage (L3) C. oncophora larvae revealed several corresponding antigenic fragments between adult worms and the fourth-stage (L4) larvae. No reactivity in the immune sera was found against the L3 stage. A previously defined complex of low molecular weight proteins (12-15 kDa) was found on both L4 and adult Cooperia stages, but not on the L3 stage. C. oncophora adults differed from the L4 larvae at the 31/32 and 37 kDa level. Several adult and L4 proteins were bound by biotinylated Concanavalin A, as was also true for L3 proteins. A 31/32 kDa glycoprotein of adult worms was recognised by a monoclonal antibody with specificity for phosphorylcholine. Using monoclonal antibodies in ELISA and Western blotting, the serum antibody response of C. oncophora-infected calves to adult worm antigen was almost entirely IgG1. Binding of the IgG1 antibodies was restricted to a complex of reduced 12-15 kDa protein(s) and a 27 kDa fragment of adult worms. The data suggest that the systemic humoral immune response of calves during a primary infection with C. oncophora consists mainly of an IgG1 response, and is directed to a non-glycosylated Cooperia protein (molecular weight estimated at 12-15 kDa under reducing conditions and 18 kDa under nonreducing conditions). This protein is probably present in both L4 larvae and adults. Since it was not bound by immune sera from calves mono-infected with several other nematodes, the 12-15 kDa protein complex may represent a Cooperia-specific component that can be used for serodiagnosis.

Acquired immunity against Cooperia spp. and Ostertagia spp. in calves: effect of level of exposure and timing of the midsummer increase.

In two experiments, groups of calves were exposed to different levels and patterns of infection with Ostertagia spp. and Cooperia spp. The experimental design simulated the stereotypic pattern of herbage infestation, including both as normal and a delayed midsummer increase, under conditions of set-stocking. After this simulated 'first grazing season', calves were followed during the subsequent winter housing. At the end of that housing period some calves were challenged with 100,000 L3 Cooperia spp. and 40,000 L3 Ostertagia spp. and slaughtered 23 days later. All previously infected calves were protected against the establishment of the challenge infection with Cooperia spp., but not against Ostertagia spp. For the latter a significant negative correlation was found between worm count and previous level of exposure to infection. During the simulated first grazing season, changes in the ratio of Cooperia to Ostertagia eggs in the faecal egg output and the genus-specific egg count were influenced by both the level of exposure and the timing of the midsummer increase. It is concluded that acquired immunity against both parasite genera develops depending on the level of exposure to infection during a first grazing season, and that delaying the midsummer increase results in a delay of the acquisition of an effective immunity as measured by faecal egg counts and the ratio of Cooperia to Ostertagia egg output.

Weight gain and the course of some estimators of gastrointestinal nematode infection in calves during winter housing in relation to the level of exposure during the previous grazing season.

In two experiments groups of calves were exposed to different levels and patterns of infection with Ostertagia spp. and Cooperia spp. The experimental design simulated the stereotypic pattern of herbage infestation, including a normal or a delayed midsummer increase, under conditions of set-stocking. After this simulated 'first grazing season', calves were monitored throughout the subsequent winter housing period. No continuing negative effects of previous infection on growth performance were observed. Calves in all groups gained on average over 0.7 kg day-1, irrespective of previous level of exposure. Differences between the experiments with respect to either level or pattern of infection during the preceding 'first grazing season' were all, to a greater or lesser extent, reflected in faecal egg counts, pepsinogen values, gastrin values and antibody titres against Cooperia spp. or Ostertagia spp. Depending on the time of sampling, pepsinogen values and antibody titres against Ostertagia spp. particularly were useful variables for assessing differences in levels of infection to which groups of calves had been exposed.

Quantitative estimation of the level of exposure to gastrointestinal nematode infection in first-year calves.

In two experiments groups of calves were exposed to different levels and patterns of infection with Ostertagia spp. and Cooperia spp. The experimental design simulated the stereotypic pattern of herbage infestation, including a normal or a delayed midsummer increase, under conditions of set-stocking. The purpose of the experiments was to investigate the accuracy of egg counts, pepsinogen and gastrin values and antibody titres as estimators of the level of exposure to infection. Faecal egg counts significantly reflected levels of exposure during the first half of the simulated grazing season. Antibody titres and pepsinogen values reflected levels of exposure best during August and September, partly depending on the pattern and range of levels of exposure. Antibody titres against Cooperia spp. were particularly useful when levels of exposure to gastrointestinal nematode infection were low. Gastrin values were elevated only at high levels of exposure, which caused large weight gain reductions, in the later part of the simulated first grazing season. It is suggested that antibody titres and pepsinogen values can be used for prognostic diagnosis, indicating whether or not control measures should be taken. Both estimators of infection correlated significantly with the realised weight gain at the end of the simulated grazing season. Egg counts in the second month after the initial infection (turnout) also may be of significant value to support decisions concerning control measures. Comparisons with data from field trials and experiments conducted by others under various conditions suggested that the conclusions of the present experiments are also valid under field conditions. Furthermore, the results supported the conclusions drawn from previous field work, that levels of exposure are often very low on commercial farms in the Netherlands.

The role of A-O-incompatible blood transfusions in porcine orthotopic liver transplantations.

The consequences of administrations of A-O-incompatible blood transfusions during porcine orthotopic liver transplantations (OLT) are described. Two series, both subjected to the same standard procedure except for the administration of compatible or incompatible blood, are compared. The striking differences in peroperative and direct post-operative morbidity, mortality, and causes of death between the two series are presented. Although not generally applied, blood transfusions in experimental surgery should undergo the same precautionary measures as blood transfusions in humans.