Effects of growth rate during the early fattening period on growth, carcass characteristics and circulating hormones in the different growth hormone genotypes of Japanese black steers

One of the bovine growth hormone (GH) genetic variants is a substitution of leucine (Leu) to valine (Val) at amino acid position 127 of the protein. The GH genotypes of 14 Japanese black steers used in the present study were Leu/Leu (A, n = 7) and Val/Val (B, n = 7). The steers in each genotype group were divided into two groups based on intended growth rate (high, 1.0 kg/day; low, 0.6 kg/day) during 10–17 months of age. The overall mean concentration of plasma GH was higher (P < 0.05) in the A group than in the B group. The serum concentration of insulin‐like growth factor‐I was higher (P < 0.05) in the B group than in the A group. The carcass weight of the A group was greater (P < 0.01) than that of the B group. However, there was no significant difference in carcass weights between the 1.0 kg/day and 0.6 kg/day groups (P > 0.05). The rib thickness of the 1.0 kg/day group was greater (P < 0.05) than that of the 0.6 kg/day group. The crude fat content of longissimus muscle was greater (P < 0.05) for the 0.6 kg/day group compared with the 1.0 kg/day group.     

Inhibitory effects of isoleucine and antagonism of the other branched-chain amino acids on fermentation parameters by mixed ruminal microbes in batch cultures and rumen simulating fermenters (Rusitec)

The inhibitory effect of isoleucine (Ile) and antagonistic effect of leucine (Leu) and valine (Val) against the inhibition by Ile were investigated using simple batch and semicontinuous cultures of mixed ruminal microbes under feeding conditions using ordinary feed (timothy hay and corn grain). In the batch culture experiment, supplementation with Ile inhibited digestion and fermentation at 8–24 h of incubation as the concentration of Ile increased up to 5 mmol/L, but these inhibitions diminished at 48 h. The inhibition caused by Ile was mitigated by the addition of Leu and Val. In a semi‐continuous culture experiment using Rusitec, digestion and fermentation of the diet was suppressed by the administration of 1 and 5 mmol/L of Ile. The daily yield of microbial‐N was also reduced by Ile, but the density of the protozoa was not. The presence of Leu and Val alleviated the inhibition by Ile. These results suggest that the dietary inclusion of Ile possibly represses the bacterial growth, feed digestion and fermentation in the rumen in ordinary feeding situations by feedback inhibition, which could be diminished in the presence of other branched‐chain amino acids. The influences of the passage and level of supplementation on inhibition by amino acids are discussed.     

Scanning electron microscopic observation of the architecture of collagen fibres in chicken M. iliotibialis lateralis

1. The collagen architecture of M. iliotibialis lateralis in chicken was observed under the scanning electron microscope after muscle maceration in NaOH. 2. Immunohistochemical methods showed Type I and III collagens to be distributed over both perimysium and endomysium. 3. Thick perimysium around secondary myofibre fasciculi was composed of many large longitudinal collagen bundles and a few small circumferential bundles. In contrast, thin perimysium around primary myofibre fasciculi showed mainly circumferential bundles. 4. Endomysium had a honeycomb-like structure and consisted of a fine collagen mesh, its main fibre striation being circumferential. 5. It is suggested that functional demand differs between thick perimysium and thin endomysium.     

Granulocyte colony-stimulating factor has no adverse effects on atherosclerotic lesions in high cholesterol-fed miniature Swine

Granulocyte colony-stimulating factor (G-CSF) is widely used to mobilize peripheral blood stem cells, and expected to restore cardiac function for patients with coronary artery diseases as a consequence of progression of atherosclerosis. Safety issues related to the administration of G-CSF to these patients, however, are still under study. The animal model for atherosclerosis was produced by feeding miniature swine a high-cholesterol diet for 3 months. G-CSF (5 or 10 microg/kg/day) was given to the animal model by daily subcutaneous injections for 10 days and 20 main arteries were evaluated pathologically. In addition, the general toxicological effects were studied on clinical signs, body weight, hematology, blood chemistry and pathology. In the G-CSF-treated groups, a variety of changes related to the major pharmacological activity of G-CSF including an increase in white blood cell (WBC) counts were observed. In many arteries, atherosclerotic lesions similar to Type I-V of the proposed classification by the American Heart Association were observed. No effects of the G-CSF treatment were seen on the histopathological findings, incidence, severity or distribution of atherosclerotic lesions. In addition, no infiltration of neutrophils to the lesions was observed. These findings suggest that the administration of G-CSF causes neither exacerbation or modification of atherosclerotic lesions nor adverse changes despite that a sufficient increase in WBC counts could be achieved in the peripheral blood.     

Evaluation of a microplate agglutination test (MAT) for serological diagnosis of canine brucellosis

A microplate agglutination test (MAT) was compared with the tube agglutinin test (TAT), a standard test for the diagnosis of Brucella canis, in terms of the sensitivity and specificity. The results showed that MAT was more sensitive, simpler to perform and easier to read the results than TAT. On top of that the MAT allows us to handle a larger number of samples at once. Using this method we conducted sero-surveillance of the prevalence of B. canis in dogs kept in an Animal Shelter located in Kanagawa Prefecture. Twelve of 485 (2.5%) showed seropositive against B. canis. These results indicate that B. canis infection in dogs is still occurring in Japan.     

Colour Doppler sonography of cystic ovarian follicles in cows

The goals of the present study were to investigate whether colour Doppler sonography can be used to differentiate temporary from persistent ovarian follicles and follicles with luteal tissue from follicles without luteal tissue and to assess the response of follicular cysts to administration of a gonadotropin releasing hormone (GnRH) analogue. Fifty-four cows having ovarian follicular structures with a diameter of >15 mm but no corpus luteum were included. These cows were examined via B-mode and colour Doppler sonography. The same examinations were repeated 10 to 12 days later, and the cows with follicular cysts (n=17) received a GnRH analogue. Blood flow was measured before and 30 min after treatment. Ten to 12 days later, the response to treatment was assessed using B-mode sonography. While 31 of 54 follicles disappeared spontaneously (temporary follicles), 23 follicles persisted and were diagnosed as cystic ovarian follicles (COFs). There was no difference between temporary follicles and COFs in regard to total area, wall thickness or the perfused area. In the luteinized follicles (n=13), based on the plasma progesterone concentration, total area was twice as large, wall thickness was three times greater and the perfused area was 4.5 times larger than those of the non-luteinized follicles (n=41). The sensitivity of diagnosing luteinized follicles was 61.5% using B-mode sonography and 92.3% using colour Doppler sonography. Twelve cows responded to GnRH, and five cows did not. There was a trend (P=0.07) toward higher (59.3%) blood flow in the cyst wall 30 min after treatment in the responding cows compared with the non-responding cows. Our results showed that the perfused area more accurately reflects active luteal tissue than wall thickness. Thus, colour Doppler sonography is superior to B-mode sonography for differentiating follicular and luteal cysts and aids in the selection of treatment. However, exact prediction of COFs destined to regress or persist and the response of COFs to treatment with a GnRH analogue were not possible using colour Doppler sonography.     

Effect of suckling on the reproductive performance and metabolic status of obese Japanese black cattle during the early postpartum period

The aim of our study was to investigate the effects of suckling on reproductive performance and metabolic status of obese (mean body condition score of more than 4.0 on a scale of 1-5) maternal Japanese Black cows during early postpartum period. We used 7 postpartum Japanese Black cattle. Four cows were suckled ad libitum (suckled) until completion of their first artificial insemination (AI), while 3 cows were not suckled at all because they were separated from their calves immediately after parturition (non-suckled). Body weight and plasma concentrations of metabolites and hormones were measured from wk 1 to 9 postpartum. Ovarian activity was detected using plasma progesterone concentration, and all cows received their first AI after application of the Ovsynch protocol at approximately 4 months postpartum. Although body weights of non-suckled cows increased during experimental period (P<0.05), those of suckled cows remained unchanged. Plasma concentrations of glucose of non-suckled cows were higher at wk 2 postpartum (P<0.05) and their levels of non-esterified fatty acid tended to be lower at wk 1 and 2 postpartum compared with suckled cows (P<0.1); however, these differences between groups were not observed with progression of postpartum period. In addition, plasma insulin concentrations of non-suckled cows were higher than those of suckled cows during experimental period (P<0.05). During sampling period (wk 0 to 9 postpartum), onset of normal ovarian cycle was observed in all non-suckled and 2 of 4 suckled cows, and it was delayed in other 2 suckled cows compared with non-suckled cows; however, 3 suckled cows conceived at the first AI after application of the Ovsynch protocol; none of non-suckled cows conceived at this time. Overall, we suggest that suckling seems to reduce increase of body weight after parturition, although it does not improve obesity, and influences conception despite delay in resumption of normal ovarian cyclicity in obese Japanese Black cows.     

Relationship of the bovine growth hormone gene to carcass traits in Japanese black cattle.

The bovine growth hormone gene (bGH) possesses three haplotypes, A, B and C, that differ by amino acid mutations at positions 127 and 172 in the fifth exon: (leucine 127, threonine 172), (valine 127, threonine 172) and (valine 127, methionine 172) respectively. The correlation between meat quality or carcass weight and these haplotypes was investigated in Japanese black cattle. Altogether, 940 bGH haplotypes were compared with respect to six carcass traits: carcass weight, longissimus muscle area, rib thickness, subcutaneous fat thickness, beef marbling score and beef colour. The frequency of the B haplotype was higher (0.421) than that of A (0.269) and C (0.311). High carcass weight and low beef marbling were associated with haplotype A (p < 0.05 and p < 0.01 respectively), whereas beef marbling was increased by haplotype C (p < 0.05). Estimated regression coefficient of the A haplotype substitution effect for carcass weight and beef marbling score were 5.55 (13.1% of the phenotypic SD) and -0.31 (17.0%) respectively. That of the C haplotype for beef marbling score was 0.20 (11.0%). The other traits showed no relationship to the haplotypes examined. The results of this investigation suggest that information pertaining to bGH polymorphisms in Japanese black cattle could be used to improve the selection of meat traits.     

A genome‐wide association study for fat‐related traits computed by image analysis in Japanese Black cattle

The objective of this study was to identify genomic regions associated with fat‐related traits using a Japanese Black cattle population in Hyogo. From 1836 animals, those with high or low values were selected on the basis of corrected phenotype and then pooled into high and low groups (n = 100 each), respectively. DNA pool‐based genome‐wide association study (GWAS) was performed using Illumina BovineSNP50 BeadChip v2 with three replicate assays for each pooled sample. GWAS detected that two single nucleotide polymorphisms (SNPs) on BTA7 (ARS‐BFGL‐NGS‐35463 and Hapmap23838‐BTA‐163815) and one SNP on BTA12 (ARS‐BFGL‐NGS‐2915) significantly affected fat percentage (FAR). The significance of ARS‐BFGL‐NGS‐35463 on BTA7 was confirmed by individual genotyping in all pooled samples. Moreover, association analysis between SNP and FAR in 803 Japanese Black cattle revealed a significant effect of SNP on FAR. Thus, further investigation of these regions is required to identify FAR‐associated genes and mutations, which can lead to the development of DNA markers for marker‐assisted selection for the genetic improvement of beef quality.     

Timing and uniformity of embryonic gene activation affect subsequent pre-implantation development of cloned bovine embryos

In the present study, we examined the timing of onset, intensity, and mosaicism of embryonic gene expression in bovine nuclear transfer (NT) embryos. The relationship between gene expression and early embryonic development was also examined. To monitor the gene expression of NT embryos, we produced NT embryos with bovine transfected fibroblasts carrying a firefly luciferase gene under the control of a chicken beta-actin promoter, an expression system that has previously been shown to be representative of embryonic gene expression in mice. Photon count imaging showed that luciferase luminescence began in NT embryos with fibroblasts 48 hours post fusion (hpf) and reached a plateau at the 4- to 8-cell stage at 60 hpf. Only 4- to 8-cell NT embryos luminescent by 60 hpf developed to the blastocyst stage. At 60 hpf, strongly luminescent embryos developed to the blastocyst stage at a higher rate (P<0.05) than embryos with weak or absent luminescence. However, embryos with mosaic luminescence developed at a much lower rate (P<0.05) than those with whole-embryo luminescence, even if the embryos exhibited strong luminescence. Our results indicate that precise and uniform embryonic gene expression at the 4- to 8-cell stage at 60 hpf may be closely related to development of bovine NT embryos to the blastocyst stage.