Effects of initial handling and training on autonomic nervous function in young Thoroughbreds

OBJECTIVE: To determine the effects of initial handling and training on autonomic nervous functions in young Thoroughbreds. ANIMALS: 63 healthy Thoroughbreds. PROCEDURE: All horses were trained to be handled and initially ridden in September of the yearling year and then trained until the following April by conventional training regimens. To obtain the heart rate (HR), electrocardiograms were recorded in the stable before initial handling and training and following 7 months of training; variations in HR were then evaluated from the power spectrum in terms of the low frequency (LF; 0.01 to 0.07 Hz) power and high frequency (HF; 0.07 to 0.6 Hz) power as indices of autonomic nervous activity. To evaluate the fitness, the V200 (velocity at HR of 200 beat/min), which is reflective of the aerobic capacity of the horse, was measured. RESULTS: Mean (+/- SE) resting HR decreased significantly from 41.5 +/- 0.8 to 38.7 +/- 0.4 beat/min following 7 months of training. The LF power of horses increased significantly from 1,037 +/- 128 milliseconds2 in September of the yearling year to 2,944 +/- 223 milliseconds2 in the following April. Similarly, the HF power increased significantly from 326 +/- 30 milliseconds2 to 576 +/- 39 milliseconds2 at the corresponding time points. The V200 increased significantly following training. CONCLUSIONS AND CLINICAL RELEVANCE: Increases in LF and HF powers indicate that parasympathetic nervous activity increases in horses by 7 months of training. The decrease in resting HR may be dependent on the training-induced increase of parasympathetic nervous activity in Thoroughbreds.     

Rumen fermentation,milk production and conjugated linoleic acid in the milk of cows fed high fiber diets added with dried distillers grains with solubles

The effects of corn dried distillers grains with solubles (DDGS) feeding on rumen fermentation and milk production in cows were evaluated using diets high in neutral detergent fiber (NDF, 45.9–46.6%). The control diet (Control) consisted mainly of hay, corn silage and concentrates. In the experimental diets, the concentrates were replaced with DDGS as 10% dry matter (DM) (10%DDGS) and 20% DM (20%DDGS). Eight cows were used for each 14‐day treatment period. Effect of DDGS feeding on DM intake was not significant. Ruminal volatile fatty acids and ammonia‐N at 5 h after feeding of 20%DDGS were decreased compared to Control, whereas protozoal count at 2 h after feeding of 20%DDGS was higher than that of 10%DDGS. Milk yield of cows fed DDGS diets was greater than that of Control, although percentages of milk protein and solids‐not‐fat were decreased by DDGS diets. The proportions of C10:0, C12:0, C14:0 and C16:0 in the milk fat decreased, and those of C18:0, C18:1, C18:2 and cis‐9, trans‐11 conjugated linoleic acid (CLA) increased markedly with elevated DDGS. Increase in trans‐11 C18:1 was observed in the rumen fluid at 5 h after feeding. These findings suggest that DDGS feeding enhanced milk yield, as well as CLA synthesis under a high dietary NDF condition.     

Changes of multi-drug resistance pattern in Salmonella enterica subspecies enterica serovar typhimurium isolates from food-producing animals in Japan

A total of 153 isolates of Salmonella Typhimurium derived from food-producing animals in Japan between 2002 and 2005 were investigated for antimicrobial resistance and phage types related to definitive phage type 104 (DT104). The predominant resistance type was resistance to ampicillin, dihydrostreptomycin, kanamycin, and oxytetracycline in bovine (45.2%, 48/104) and resistance to dihydrostreptomycin and oxytetracycline in porcine isolates (58.7%, 27/48). DT104-related phage type was found in 32 of 104 bovine isolates, two of 48 porcine isolates, and one of eight isolates from poultry, showing that the proportion of the phage type in S. Typhimurium isolates from cattle and pigs significantly (P<0.01) decreased from 71.9% and 31.4% in 1999-2001 to 30.8% and 4.1% in 2002-2005, respectively.     

A Hepatocellular Adenoma in a Diet-induced Obese Mouse

A hepatic nodule was noted in a C57BL/6J mouse with diet-induced obesity at 53 weeks of age. Macroscopically, a protruding yellowish white nodule was observed on the visceral surface of the left lateral lobe. Light microscopy demonstrated clear demarcation from the compressed adjacent parenchyma, with loss of the distinct lobular pattern. The proliferating cells of the lesion varied in shape and showed cellular atypia and prominent nucleoli along with vacuoles of various sizes. Some of the cells contained various-sized eosinophilic inclusion bodies in their cytoplasm, and electron microscopy revealed the presence of lipid droplets in the rough endoplasmic reticulum. Eosinophilic inclusions were observed as electron dense granular material in the rough endoplasmic reticulum, with one or a few low density central cores. A diagnosis of hepatocellular adenoma was made based on these findings.     

Establishment of embryo transfer in the musk shrew (Suncus murinus)

The present study established techniques to induce pseudopregnancy, in vitro oocyte cultures from pronuclear to 2- to 4-cell stages, and embryo transfer in musk shrews, a reflex ovulator. Offspring were subsequently obtained by transferring in vivo-developed or in vitro-cultured embryos. Female musk shrews received human chronic gonadotropin (hCG), with or without mating stimuli, from vasectomized males to produce pseudopregnant recipients. Embryos at the 2- to 4-cell stage were collected 44–48 h after mating. Another set of embryos was collected 26–27 h after mating and then cultured for 20 h from the pronuclear to 2- to 4-cell stages. Subsequently, embryos were transferred into the oviducts of pseudopregnant recipients 24 or 48 h after the induction of pseudopregnancy. Offsprings were successfully obtained from recipients that received hCG 24 h before embryo transfer, regardless of mating stimuli. These techniques may be valuable for producing transgenic musk shrews.     

Detection of rickettsial DNA in ixodid ticks recovered from dogs and cats in Japan

DNA from ticks recovered from 1137 dogs and 133 cats from all over Japan were examined for Rickettsia infection by citrate synthase gene (gltA)-based PCR and partial nucleotide sequencing. A total of 91 dog tick samples and 18 cat tick samples showed a single band of the appropriate size in the nested PCR. Sequence analysis was successfully performed on 102 samples. DNA of Rickettsia japonica or closely related Rickettsia spp. strains were detected from 38 ticks in 16 prefectures mainly in western Japan. The other 33, detected from 13 prefectures including Hokkaido and Okinawa, were found to be Rickettsia helvetica or closely related strains. A total of 29 DNA that showed highest homology with Rickettsia akari or closely related strains were detected in 19 prefectures, widespread throughout Japan. Rickettsia canada-like DNA was detected from Haemaphysalis sp. removed from a dog in Fukuoka, and ;Candidatus Rickettsia tarasevichiae'-like DNA was from Ixodes sp. removed from a dog in Hokkaido.     

Serological survey of Rhodococcus equi infection in horses in Hokkaido.

Serological survey of Rhodococcus equi infection in horses in Hokkaido was performed using ELISA. Of 2,879 horse sera, 318 (11.0%) gave antibody-positive (OD greater than or equal to 0.3) reactions. The antibody-positive rate of female was significantly higher (p less than 0.01) than that of male, and no statistical difference between Anglo-Arab and thoroughbred was detected in the antibody-positive rate. The maximum antibody-positive rate (27.1%) was shown at 14 years of age. The antibody-positive rates on the 160 farms were found to vary widely from 0 to 78.9%. A significant difference (p less than 0.01) in the antibody-positive rate was detected among horse farms. It was elucidated that 100 (62.5%) out of 160 horse farms had an antibody-positive horse. These results indicate that R. equi was widespread on horse farms, and the level of environmental contamination with R. equi differed among horse farms.