ABSTRACT
Precise normalization with reference genes is necessary, in order to obtain reliable relative expression data in response to gastrointestinal nematode infection. By using sheep from temperate regions as models, three reference genes, viz., ribosomal protein LO (RPLO), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and succinate dehydrogenase complex subunit A (SDHA), were investigated in the abomasum, abomasal lymph nodes and small intestine of Brazilian Somalis sheep, either resistant or susceptible to gastrointestinal nematodes infections. Real time PCR was carried out by using SYBR Green I dye, and gene stability was tested by geNorm. RPLO was an ideal reference gene, since its expression was constant across treatments, presented lower variation, and was ranked as the most stable in abomasum and lymph node tissues. On the other hand, SDHA was the most stable in the small intestine followed by RPLO and GAPDH. These findings demonstrate the importance of correctly choosing reference genes prior to relative quantification. In addition, we determined that reference genes used in sheep from temperate regions, when properly tested, can be applied in animals from tropical regions such as the Brazilian Somalis sheep.
ABSTRACT
Eprinomectin is the only avermectin approved for use to control gastrointestinal nematodes in lactating cows. Some studies in the USA and Europe have also demonstrated that this drug is highly effective in small ruminants. The aim of the present work was to evaluate the anthelmintic efficacy of pour-on eprinomectin in Anglo-Nubian goats at the end of lactation. Twenty-four goats were used, naturally infected with gastrointestinal nematodes, and divided into two groups: control and treated with eprinomectin (Eprinex, Merial, pour-on 0.5%) at a dose of 850 microg/kg. Counts were made of the eggs per gram (EPG) of feces, along with coprocultures, on days -7, 0, 4, 8, 11, 15, 18, 22, 25 and 29. The milk production of each group was recorded throughout the experiment. The coprocultures detected 98% Haemonchus contortus and 2% Oesophagostomum. There was no statistically significant difference (P > 0.05) in daily milk output between the two groups. Eprinomectin at the tested dosage was not effective (P > 0.05) in reducing the EPG. Positive results would serve as basis for use of an avermectin without residues in dairy goats, providing a scientific basis for greater food safety.
