No abstract

Agricultural ruminants usually harbour mixed infections of gastrointestinal nematodes. A specific diagnosis is important because distinct species can differ significantly in their fecundity and pathogenicity. Haemonchus spp. and Cooperia spp. are the most important gastrointestinal nematodes infecting ruminants in subtropical/tropical environments. In Brazil, C. punctata is more adapted to cattle than sheep. Additionally, C. spatulata appears to be more adapted to cattle, whereas C. curticei is more adapted to sheep. However, infection of sheep with C. punctata is common when cattle and sheep share the same pasture. Although morphological analyses have been widely used to identify nematodes, molecular methods can overcome technical limitations and help improve species-specific diagnoses. Genetic markers in the first and second internal transcribed spacers (ITS-1 and ITS-2, respectively) of nuclear ribosomal DNA (rDNA) have been used successfully to detect helminths. In the present study, the ITS-1 region was analysed and used to design a species-specific oligonucleotide primer pair to identify C. curticei. The polymerase chain reaction (PCR) product was sequenced and showed 97% similarity to C. oncophora partial ITS-1 clones and 99% similarity to the C. curticei sequence JF680982. The specificity of this primer pair was corroborated by the analysis of 17 species of helminths, including C. curticei, C. punctata and C. spatulata. Species-specific diagnosis, which has implications for rapid and reliable identification, can support studies on the biology, ecology and epidemiology of trichostrongylid nematodes in a particular geographical location.

To evaluate the effects of Diet and corticosteroid-induced immune suppression during infection by Haemonchus contortus, 28 lambs were allocated to one of four groups treated as follows: Group Basal Diet - Normal; Group Basal Diet - Immune-Suppressed; Group Supplemented Diet - Normal; and Group Supplemented Diet - Immune-Suppressed. The Basal Diet contained Cynodon dactylon (cv. coast cross) hay with 82 g crude protein (CP)/kg dry matter (DM), which was provided to the lambs in all groups ad libitum. In addition, animals on the Supplemented Diet received daily a commercial concentrate containing 171 g CP/kg DM, which was offered in an amount corresponding to 3% of the animal's live weight. The Immune-Suppressed groups received treatments with the glucocorticoid methylprednisolone sodium succinate (1.33 mg/kg of body weight), administered weekly. All lambs received a single infection with 4000 H. contortus infective larvae (L3) and were euthanised 28 days post-infection. Differences in pH and in the short-chain fatty acid (SCFA) concentrations occurred in rumen as a result of the distinct Diets offered to lambs. Such changes, however, did not have any apparent effect on larvae exsheathment and/or larvae survival inside the rumen, with all groups presenting similar worm burdens. However, animals on the Supplemented Diet presented reductions in worm growth and faecal egg counts. There was a significant effect of the Diet on the IgG levels against total antigens of H. contortus L3 from 7 to 27 days post-infection, with supplemented animals showing higher overall mean values (P<0.05). The immunosuppressive treatments had no effect on worm burden despite the reduction in the numbers of inflammatory cells in the abomasal mucosa of the Immune-Suppressed groups. These groups showed longer worms and females with more eggs in comparison with their counterparts fed each Diet; however, only the length of males was significantly affected (P<0.05). In conclusion, the changes caused in the rumen contents by supplementation with concentrate did not impair H. contortus establishment.

This study aimed to determine the occurrence of gastrointestinal and pulmonary parasites in calves and to evaluate seasonal and age patterns in parasitism. For this, we used 140 clinically healthy crossbreed calves (two to 12 months old) that belonged to two private farms in the municipalities of Botucatu (n=53) and Manduri (n=87), São Paulo state, Brazil. The calves were monitored for 12 months (from September 2014 to August 2015). Fecal samples were collected directly from the rectum every three months. Fecal egg counts were determined using the modified McMaster technique with a sensitivity of 50 eggs per gram of feces (EPG). Coproculture was performed on pooled samples to identify Strongylida infective larvae. First-stage larvae of Dictyocaulus viviparus were extracted by a modified Baermann method. The data showed non-normal distribution (Shapiro-Wilk) and the nonparametric Kruskall-Wallis test was employed to evaluate the EPG data by seasons and age groups. Dunn’s post-test was used for multiple comparisons (P<0.05). The calves from Manduri farm showed significantly higher fecal egg counts (P<0.0001) in the winter when compared to other seasons. At Botucatu farm, young calves (2-3 months old) showed significantly higher EPG than old calves (8-12 months) (P=0.01). The prevalence and overall mean of animals positive for Strongylida type-eggs were 81.1% and 340 in Botucatu, respectively, versus 83.9% and 854 in Manduri, respectively. Furthermore, we found Strongyloides spp., Moniezia spp., and Trichuris spp. eggs and Eimeria spp. oocysts. The prevalent genera in all coprocultures in decreasing order were: Cooperia spp., Haemonchus spp., Oesophagostomum spp., and Trichostrongylus spp. First-stage larvae of Dictyocaulus viviparus were found only in Botucatu farm samples throughout the year, except in spring.

The effect of four diets on the performance of Dorper lambs that were artificially mix-infected with 1000 infective larvae (L3) of Haemonchus contortus and 1000 L3 of Trichostrongylus colubriformis every three days for 12 weeks was evaluated. For each diet, one infected group (n = 7) and one control group (n = 4) were set up. The four diets contained the following proportions of hay (H) and concentrate (C): Diet 1 - 100%H; Diet 2 - 75%H:25%C; Diet 3 - 50%H:50%C; Diet 4 - 25%H:75. All the infected groups showed decreases in mean packed cell volume (PCV) and total plasma protein, especially the Diet 1-infected, which was also the group with the highest fecal egg count. The diets and infection had significant effects (P < 0.05) on daily body weight gain (DBWG), cold carcass weight and daily food consumption. The control and infected groups had mean DBWG (in kg), respectively, of 0.048 and 0.025 with Diet 1; 0.082 and 0.067 with Diet 2; 0.188 and 0.189 with Diet 3; and 0.303 and 0.221 with Diet 4. In conclusion, the infection affected the productive performance regardless of the diet; however, with increased metabolizable protein and energy, the risk of occurrence of anemia and hypoproteinemia diminished.