Relationship between the stockperson's attitudes and dairy productivity in Japan

The aim of this study is to identify the factors that comprise farmer attitudes toward dairy cows and jobs in Japan, and examine the relationship between these attitudes and dairy productivity. At first, we executed a questionnaire survey to determine factors that comprise attitudes of farmers toward their jobs and dairy cows, and three factors were extracted. These were named as ‘Positive beliefs to cows’, ‘Negative beliefs to cows’ and ‘Job satisfaction’, respectively. Second, we examined the relationships between attitude and dairy productivity in 35 dairy farms. The positive beliefs scores correlated positively both with milk yield and milk urea nitrogen concentration. We found there to be three farm groups by cluster analysis using three attitude score. The group B farms showed significantly higher positive beliefs scores and job satisfaction scores; on the other hand, the group C farms showed significantly lower positive beliefs scores and higher negative belief scores. The milk yield in group B was significantly higher than that in group C. This study showed that Japanese farmers' attitudes toward cows considerably resemble those seen in previous studies in Western cultures. Positive attitudes toward cows could enhance stockmanship, and could improving animal welfare and productivity.     

Reduction of dietary lysine increases free glutamate content in chicken meat and improves its taste

Taste is a crucial factor of meat quality, and amino acids are important taste‐active components in meat. Here, the effects of dietary lysine (Lys) content on taste‐active components in meat, especially free glutamate (Glu), were investigated. Twenty‐eight‐day‐old broilers (Gallus gallus) were fed diets with graded Lys content of 90% or 100% of the recommended Lys requirement, (according to the National Research Council, 1994 ) for 10 days. Free amino acid content in meat and sensory scores of meat soup were estimated. Free Glu content, the main taste‐active component of meat, was significantly increased by a reduction of dietary Lys. Compared with the Lys 100% group (control), free Glu concentrations of meat were increased by 35.7% in the Lys 90% group (P < 0.05). In addition, free glycine, valine, isoleucine, leucine, histidine and threonine concentrations of meat were significantly increased in the Lys 90% group (P < 0.05). Sensory evaluation of meat soup made from the Lys 100% and 90% groups indicated different meat tastes. Sensory scores of taste intensity, umami and kokumi tastes were significantly higher in the Lys 90% group. These results suggest that a reduction of dietary lysine increased free glutamate content in meat and improved its taste.     

Association between preoperative characteristics and risk of anaesthesia-related death in dogs in small-animal referral hospitals in Japan

Objective

To explore the major risk factors linking preoperative characteristics and anaesthesia-related death in dogs in referral hospitals in Japan.

Optimal timing for canine artificial insemination with frozen semen and parentage testing by microsatellite markers in superfecundency

Parentage testing was performed in sixteen litters by canine artificial inseminations with frozen semen from different sires on Days 5 and 7 after the LH surge. It became apparent that only 25% of dams had superfecundation, but 43.8% of dams were whelped after insemination only on Day 5 after the LH surge and 31.3% of dams after insemination only on Day 7. Of the total 87 puppies, 46% were born after insemination on Day 5 after the LH surge and 54% after insemination on Day 7. This result strongly suggested that canine artificial insemination with frozen semen could be sufficiently successful also on Days 5 and 7 after the LH surge.     

Expression analyses of sex steroid-regulated genes in neonatal rat hypothalamus

Estrogen plays an important role in sexual differentiation of the brain in rats during the perinatal period. To elucidate molecular mechanisms underlying sexual differentiation of the brain, in this study we investigated genes differentially expressed between sexes or induced to express by estrogen in neonatal rat hypothalamus using DNA microarray analysis in combination with real-time RT-PCR. It was found that the levels of expression of the genes encoding glutamic acid decarboxylase 65 and coronin 1b were higher in male than female hypothalamus on postnatal day (PN) 5 and those of collagen type 3 alpha1 and thioredoxin reductase 2 genes in female hypothalamus on PN5 were decreased and increased, respectively, by treatment with estradiol on PN2. Then the developmental changes in the expression of these 4 genes were examined from 1 day before the parturition to PN9, and they all showed sexual dimorphic patterns. In addition, dependence of the expression of these genes on either estradiol, testosterone or dihydrotestosterone during the neonatal period was confirmed. These results suggest that these four genes are involved in sexual differentiation of the rat brain, and that androgen per se as well as estrogen may take part in the processes.     

Generation of transgenic rats expressing enhanced green fluorescent protein in gonadotropin-releasing hormone neurons

Hypothalamic gonadotropin-releasing hormone (GnRH) neurons govern reproductive function by controlling the release of gonadotropins from the pituitary. To facilitate identification of living GnRH neurons, here we attempted to generate transgenic rats that express enhanced green fluorescent protein (EGFP) in GnRH neurons. About 3 kb of rat GnRH promoter region was inserted into the EGFP reporter cassette, and the expression of EGFP fluorescence was confirmed in several cell lines following transient transfection. Then we successfully generated a transgenic rat by injecting linearized GnRH-EGFP transgene into the pronuclei of fertilized oocytes. The GnRH-EGFP transgenic rats expressed EGFP in the brain, but not in the ovary, testis or thymus. Immunohistochemical examination revealed that detectable EGFP fluorescence was confined to the cell body of GnRH-immunoreactive neurons in the septum and preoptic area, while no EGFP signal was discernible in the median eminence where abundant GnRH-immunoreactive fibers were observed. The mean percentage of EGFP-positive cells in the GnRH-positive cells was 76.3%. The GnRH-EGFP transgenic rats generated in the present study will enable characterization of properties of individual GnRH neurons.     

Nucleotide sequence polymorphisms of beta1‐, beta2‐, and beta3‐adrenergic receptor genes on Jinhua,Meishan, Duroc and Landrace pigs

The full amino acid coding sequences of adrenergic receptor genes beta1, beta2, and beta3 (ADRB1, ADRB2, and ADRB3)were determined for Jinhua, Meishan, Duroc and Landrace pigs. Non‐synonymous substitution of Arg458Pro was found in the porcine ADRB1 gene, resulting in a 469 amino acid sequence. Continuous substitutions of Asn29Asp and Glu30Gln were found in the porcine ADRB2 gene, resulting in a 418 amino acid sequence. Additionally, a Lys30 polymorphism of the ADRB2 gene was found in the Jinhua pigs. There were three non‐synonymous substitutions of Asn24Thr, Arg264Gln and Asn398Asp on the porcine ADRB3 gene. A thymine insertion in the ADRB3 gene, resulting in a protein with two fewer amino acids, was found in the Jinhua and Meishan pigs. To assess the effect of ADRB polymorphisms on porcine subcutaneous fat layer thickness, we calculated the genetic frequency of the variants in fatty and lean groups, each consisting of 24 pigs that were crossbreds of Duroc and Jinhua pigs. The effect of the ADRB3 gene polymorphism was not evaluated, because there was insufficient variation on the ADRB3 gene in the examined groups. Although Fisher's exact test showed no significant difference in the frequency of ADRB1 and ADBR2 variants between the two groups, the Arg458 variant of ADRB1 was higher (P = 0.11) in the lean group, and pigs in that group had a thinner fat layer than did those with the Pro458 variant. These results imply a possibility of ADRB1 polymorphism as a minor factor in porcine fat layer thickness. The Asp29 variant of ADRB2 was higher in the lean group (P = 0.11), and the Glu30 variant was higher in the fatty group (P = 0.15), but the Asp29 variant was found only in the Chinese pigs. Thus, the effect of ADRB2 polymorphisms was not clear in this study.     

Low pathogenicity H5N2 avian influenza outbreak in Japan during the 2005-2006

At the end of May 2005, a low-pathogenicity avian influenza (LPAI) virus of subtype H5N2 was isolated for the first time from chickens in Japan. Through active and epidemiological surveillance, 5.78 million chickens on 41 farms were found to be affected and 16 H5N2 viruses were isolated. Antigenic analysis revealed antigenic similarity of these isolates. Phylogenetic analysis showed that they originated from a common ancestor and clustered with the H5N2 strains prevalent in Central America that have been circulating since 1994. Experimental infection of chickens with the index isolate (A/chicken/Ibaraki/1/05) demonstrated that this virus replicated efficiently in the respiratory tract without clinical signs, and dust-borne and/or droplet-borne transmission was considered as a possible mode of transmission. These results suggested that the H5N2 LPAI viruses isolated in Japan were highly adapted to chickens.     

Regulation of free glutamate content in meat by dietary lysine in broilers

Regulation of taste is important for improving meat quality and glutamate (Glu) is one of the important taste‐active components in meat. Here, the effects of dietary lysine (Lys) content on taste‐active components in meat, especially free Glu, were investigated. Fourteen‐day‐old broiler chicks (Gallus gallus) were fed on diets containing 100% or 150% of the recommended Lys content for 10 days. Concentrations of free amino acids in plasma, muscle and liver were measured. The levels of messenger RNAs (mRNAs) for enzymes related to Glu metabolism were determined in muscle and liver. The concentration of muscle metabolites was also determined. The free Glu content in muscle of chicks fed the Lys150% diet was increased by 44.0% compared with that in chicks fed the Lys100% diet (P < 0.01). The mRNA level of lysine α‐ketoglutarate reductase, which is involved in Lys degradation and Glu production, was significantly increased (P < 0.05) in the Lys150% group. Metabolome analysis showed that the Lys degradation products, muscular saccharopine, pipecolic acid and α‐aminoadipic acid, were increased in the Lys150% group. Our results suggest that free Glu content in muscle is regulated by Lys degradation. These results suggest that a short‐term feeding of high‐Lys diet could improve the taste of meat.     

Pathogenicity of border disease virus FNK2012-1 strain isolated from a pig in the natural host,sheep

A first isolation of border disease virus (BDV) in Japan was from a pig on a farm without keeping any ruminants. Our previous study showed that this BDV, termed the FNK2012-1 strain, replicated inefficiently in swine-derived cells compared with those of ruminant origin. Pigs inoculated with this virus showed neither clinical symptoms nor viremia. In this study, we evaluated the pathogenicity of the FNK2012-1 strain in sheep, its natural host. The inoculated sheep showed clinical symptoms and transient viremia. Seroconversion was observed in the inoculated sheep. These results suggest that the FNK2012-1 strain was introduced from sheep and has not yet adapted to swine. Therefore, surveillance of border disease in Japan is necessary among both the swine and ruminant populations.