Anthelmintic resistance in Australian sheep nematode populations

SUMMARY The resistance status of gastro–intestinal nematodes to anthelmintics was evaluated on 881 sheep farms throughout Australia during 1991–92. Resistance was shown to be widespread. Overall, 85% of farms had sheep infected with nematodes resistant to benzimidazole, 65% to levamisole and 34% to combination (benzimidazole + levamisole) products. Resistance to ivermectin was not detcted. On only 9% of farms did all anthelmintic groups reduce egg counts by greater than or equal to 95%. The culture of faeces from untreated sheep showed Telodorsagia circumcincta, Trichostrongylus spp, Chabertia ovina and Haemonchus contortus to be the principal species. The nature and prevalence of resistance was not significantly correlated with stocking rate. However, resistance to combination products was almost twice as prevalent on farms in areas with an average annual rainfall of greater than 500 mm.     

Effect of some electrolytes on in vitro rumen microbial protein synthesis in buffaloes.

In vitro studies were carried out to examine the effect of MnCl2, MgCl2, CoCl2 and CaCl2 on protein synthesis by rumen microorganisms obtained from fistulated buffalo calves (Bubalus bubalis). The concentration of the electrolytes in stained rumen fluid (SRF) ranged from 1 to 20, 1 to 20, 0.25 to 5 and 1 to 20 mM, respectively. MnCl2 (15 mM), MgCl2 (10 mM), CoCl2 (2.5 mM) and CaCl2 (20 mM) increased the protein content in the incubation mixture (IM) by 501, 230.8, 537.6 and 84% and the per cent incorporation of 35S from (NH4)2 35SO4 into microbial protein by 125.6, 108.5, 113.4 and 40.3, respectively, over the control values, when the incubation lasted 8 h. The NH3-N content in IM decreased by 8, 14, 43 and 16% when 10 mM MnCl2, 20 mM MgCl2, 1 mM CoCl2 and 1 mM CaCl2, respectively, was added and the incubation lasted 6 h. The reasons for increased protein biosynthesis by rumen microorganisms in the presence of the above electrolytes are discussed.     

Comparison of two methods for determining in vitro intestinal absorption of nutrients using rats fed different diets

Absorption of sucrose, glucose, leucine and aspartate was studied using intestinal everted sac of rats fed on french bean diets namely PDR-14, HUR-137 and HUR-15 using casein as a control. Absorption of nutrients was monitored spectrophotometrically and by¹⁴C radio assay of metabolites using scientillation counting. The absorption pattern of amino acids was found to be similar but of glucose and sucrose differed. Glucose was found to be more absorbed than sucrose in spectrophotometer assay and the pattern reversed in radio assay. Absorption of sucrose and leucine were higher by rats fed on HUR-137 diet and similarly, more aspartate was absorbed when fed on HUR-15 diet as demonstrated by both the methods. Rats fed on HUR-137 diet exhibited higher glucose absorption as shown by spectrophotometric assay, but rats on HUR-15 diet by radio assay. Absorption of nutrients differed significantly between casein and french beans.