Metabolic and microbial responses in western crossbred and Meishan growing pigs fed a high-fiber diet

Four Duroc x White composite crossbred (21.8 +/- 1.0 kg BW) and four 12-wk-old Meishan purebred (20.7 +/- 1.6 kg BW) growing barrows were used to determine the relative breed differences in metabolic and microbial responses to a high-fiber diet. The pigs were trained to consume 700 g of a diet containing 35% (as-fed basis) dehydrated alfalfa meal once daily. The pigs' daily intakes of DM, N, GE, NDF, and ADF were 610 g, 16.6 g, 2.64 Mcal, 150 g, and 88 g, respectively. On d 12 after surgical catheterization of the portal vein, ileal vein, and carotid artery, a 3-d total urine and feces collection was conducted. On d 24 after surgery, each pig was placed in an open-circuit calorimeter, and its catheters were connected to a system for simultaneous measurements of oxygen consumption by portal-drained viscera and by whole body, and the net portal absorption of VFA after a 24-h fasting and during a 5-h postprandial period. The VFA measured included acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids. A second 3-d total urine and feces collection was conducted on d 30 after surgery. There were no differences (P = 0.13) between the first and second collections in apparent total-tract digestibility coefficients for nutrients and N retention of pigs. Compared with Duroc x White composite crossbred pigs, Meishan pigs had lower (P = 0.05) apparent digestibility coefficients for DM, N, NDF, hemicellulose, and N retention, but their portal-drained viscera used a greater (P = 0.05) fraction of whole-body oxygen consumption. No differences (P = 0.12) were found between Duroc x White composite crossbred and Meishan pigs in total viable bacteria and cellulolytic bacteria from fecal samples, in vitro digestibility of alfalfa NDF fractions by fecal inocula, whole-body oxygen consumption, net portal absorption of VFA, total energy of absorbed VFA, and the potential of absorbed VFA for meeting the energy needs for whole-body heat production. These results indicate that, in contrast to previous beliefs, the ability of Meishan growing pigs to utilize a high-fiber diet is not superior to that of Duroc x White composite crossbred growing pigs.     

Mutations in the juxtamembrane domain of c-KIT are associated with higher grade mast cell tumors in dogs

Mast cell tumors are among the most commonly seen tumors of the skin in dogs and are more highly aggressive than mast cell tumors of other species. Some breeds display a markedly higher incidence of mast cell tumor development than others and appear to have some genetic predisposition. Recently, mutations have been found in canine mast cell tumor tissues and cell lines within the juxtamembrane domain of the protooncogene c-KIT In previous studies utilizing a small number of cases, no association between the presence of a mutation and the breed of dog or grade of the tumor could be identified. An expanded study with a larger sample set was performed to explore this possibility. The juxtamembrane domain of c-KIT was amplified using the polymerase chain reaction from genomic DNA preparations of 88 paraffin-embedded mast cell tumors from selected breeds. Mutations, consisting of duplications and deletions, were found in 12 of the tumors. A significant association was found between the presence of a mutation and a higher grade of tumor but not between breed and grade or between breed and the presence of a mutation.     

Phylogenetic analysis of Trypanosomatina (Protozoa: Kinetoplastida) based on minicircle conserved regions

Phylogenetic relationships within the suborder Trypanosomatina were inferred from the kinetoplast DNA minicircle conserved region sequences. Trees built using distance-matrix (Neighbor-Joining) and maximum parsimony methods showed that the minicircle conserved regions (CRs) provide a sensitive and specific molecular marker suitable for phylogenetic analyses of subspecies and strains of trypanosomatid flagellates, as testified by the subdivision of the genus Leishmania into the subgenera Leishmania. Viannia and Sauroleishmania. However, since Phytomonas and monogenetic parasites of insects represent the earliest diverging groups, the CRs do not seem to be useful for inference of relationships among major lineages of the order Kinetoplastida.     

Effect of virginiamycin supplementation on the performance of young grazing cattle

Three experiments have been conducted to study the effect of virginiamycin in young grazing-bulls (Experiment 1) and heifers (Experiments 2 and 3). Rotational grazing on permanent grassland was practised and animals were supplemented with 1 kg dried sugarbeet pulp per head daily. Control groups did not receive virginiamycin via the supplement, while it was incorporated at 120, 300 and 200 mg kg⁻¹ for the treatment groups in Experiments 1 to 3 respectively.
Average daily liveweight gain was significantly increased from 0·59 to 0·72 kg in Experiment 1 and from 0·73 to 0·81 kg in Experiment 3, but was not affected in Experiment 2 (0·51 vs 0·55 kg). Virginiamycin also increased liveweight gain per ha by 12, 7 and 13%, respectively, for the three experiments. Grazed area per animal was not enlarged to the same extent as the calculated daily energy allowances, which may suggest an improved digestibility and/or rumen fermentation.     

Resistance to benzimidazole and macrocyclic lactone anthelmintics in cattle nematodes in Argentina

In April 2003, persistent scouring and ill-thrift that was reported in calves form an intensive beef rearing operation in central Argentina despite treatments with benzimidazole and ivermectin. In order to conduct a controlled faecal egg count reduction test on this herd, 40 calves 5-8-months-old were selected on the basis that they had a nematode eggs per gram (epg) of faeces count greater than 150. Animals were divided into four groups (1-4) of 10 calves. Calves of groups 1-3 were treated, respectively, with subcutaneous injection of ivermectin (200 mcg/kg), ricobendazole (4 mg/kg) and levamisole (7.5 mg/kg), while calves of group 4 remained as untreated controls. The egg count reductions carried out 10 days later were lower than 15% in calves treated with ivermectin and ricobendazole, but 100% in animals receiving levamisole. Pooled post-treatment faecal cultures showed larval percentages of 92 and 95 for Haemonchus and 8 and 5 for Cooperia in the faeces of calves treated with ivermectin and ricobendazole, respectively. This is the first reported case of Haemonchus parasiting cattle showing simultaneous resistance to avermectins and benzimidazole type anthelmintics.