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DNA methylation is an important factor for the regulation of gene expression in early embryos. It is well known that the satellite I sequence is more heavily methylated in bovine somatic cell nuclear transfer (NT-SC) embryos than in embryos derived from in vitro fertilization (IVF). However, the methylation status of bovine embryos obtained by other procedures is not well known. To clarify DNA methylation levels of bovine embryos obtained from various procedures, we examined satellite I sequences in bovine blastocyst (BC) embryos derived from NT-SC, NT using embryonic blastomeres (NT-EM), in vivo (Vivo), IVF and parthenogenetic treatment (PA). Furthermore, in order to evaluate the efficacy of DNA demethylation by the NT procedure, we determined the DNA methylation levels in bovine embryos in which NT was recapitulated (Re-NT). Although the DNA methylation levels in the NT-SC embryos were higher than those in the other embryos, the NT-EM embryos exhibited lower DNA methylation levels. The satellite I sequence in the NT-SC embryos was more demethylated than that in the donor cells. Although the DNA methylation level in the individual NT-SC embryos showed variation, the full-term developmental efficacy of these embryos were not different. These findings suggest that the methylation level of the satellite I sequence at the BC stage is not related to the abnormalities of bovine embryos produced by NT-SC. There was no difference in methylation levels between Re-NT and NT-SC embryos. Our results indicated that the DNA methylation status differed among embryos produced by various methods and that at least some of the demethylation of the donor cell genome occurred in the recipient cytoplast after NT-SC, but the demethylation ability of the NT procedure was noted in the first NT but not in the second NT.

We recently reported the intraspecies transmission of L-type atypical bovine spongiform encephalopathy (BSE). To clarify the peripheral pathogenesis of L-type BSE, we studied prion distribution in nerve and lymphoid tissues obtained from experimentally challenged cattle. As with classical BSE prions, L-type BSE prions accumulated in central and peripheral nerve tissues.

application/pdf, Theileria orientalis is one of the benign species of Theileria that is widely distributed in Japan and is sometimes responsible for serious economic losses in the livestock industry. In the present study, we surveyed the current status of T. orientalis infection in grazing cattle in the eastern areas of Hokkaido (Taiki, Otofuke, Shintoku, and Shin-Hidaka districts) using molecular methods, as well as traditional methods, of diagnosis. The genes encoding the major piroplasm surface protein (MPSP) and p23 of T. orientalis were identified using highly detectable polymerase chain reaction (PCR). Results of the MPSP-PCR assay indicated that grazing cattle in these districts, after about 1.5 months pasturage, showed high rates of infection, ranging from 10.0-64.8%. Although the main MPSP and p23 genotypes detected were the Ikeda-or Chitose-types, an MPSP gene closely relating to that found in Okinawa prefecture, and a p23 gene closely relating to the Australian (Warwick) Buffeli-type gene, were found in the cattle in Shintoku and Shin-Hidaka districts. The present survey indicated that there were at least five types of T. orientalis classified by their MPSP genes in Hokkaido, Japan, and that T. orientalis infection rates are still high in this region.

Band 3 deficiency with hereditary spherocytosis and hemolytic anemia in Japanese black cattle, band 3(Bov.Yamagata), is caused by a total lack of band 3 protein with an autosomal dominant inheritance. Genotyping for band 3 deficiency and sexing were successfully achieved in biopsied embryo cells with efficiencies of 98.4% and 97.4%, respectively. Transfer of the embryo that was determined as homozygous for the mutant allele into a recipient cow resulted in the production of a fetus exhibiting the genotype and red cell phenotypes characteristic of band 3(Bov.Yamagata). These results demonstrate that our procedure is reliable and applicable to produce animals free from or homozygous for the mutant allele by breeding carrier animals.

Loop-mediated isothermal amplification (LAMP) is a novel DNA amplification method that amplifies a target sequence specifically under isothermal conditions. The product of LAMP is detected by the turbidity of the reaction mixture without electrophoresis. The objective of this study was to develop a rapid sexing method for bovine preimplantation embryos using LAMP. The first experiment was conducted to optimize the DNA extraction method for LAMP-based embryo sexing. The DNA of single blastomeres was extracted using three methods: heat, NaOH, and proteinase K-Tween 20 (PK-TW) treatments. Sexing was performed with two LAMP reactions, male-specific and male-female common reaction, after DNA extraction. The rates of correct determination of sex were 88.9-94.4%, with no difference among methods. The sensitivity and accuracy of LAMP-based embryo sexing were evaluated in the next experiment. The proportion of samples in which the sex was correctly determined was 75-100% for one to five biopsied cells. Lastly, in vivo-derived embryos were examined to verify the usefulness of LAMP-based embryo sexing, and some of these fresh, sexed embryos were transferred into recipient animals. The time needed for sexing was

Renal tubular dysplasia is an autosomal recessively inherited disorder in Japanese black cattle that is due to deletion mutations in the claudin-16 gene and causes chronic renal failure and death of affected animals. Here, we report a multiplex-PCR procedure to determine the genotype for claudin-16 deficiency in preimplantation embryos. The presence or absence of the wild-type and mutant allele(s) was precisely detected with the multiplex-PCR using as little as 5 pg of genomic DNA from leukocytes. When biopsied embryo cells were examined for claudin-16 deficiency, 97.2% of genotypes were consistent with the PCR results obtained for the corresponding embryos. In addition, sexing of embryos by PCR was performed using an aliquot of DNA extracted from biopsied embryo cells, and determination of claudin-16 genotype and sex was successfully achieved with an efficiency of 91.7% for claudin-16 genotyping and 83.3% for sexing. The production of a 100-day fetus that was male and homozygous for claudin-16 deficiency, as expected from the analysis of biopsied embryo cells, gave evidence of the reliability and applicability of this procedure for preventing the transmission of this disease and for enabling advances in animal breeding.

We evaluated the usefulness of loop-mediated isothermal amplification (LAMP) in detecting specific gene sequences of Mycobacterium avium subsp. paratuberculosis (MAP). A total of 102 primer sets for LAMP was designed to amplify the IS 900 , HspX, and F57 gene sequences of MAP. Using each of two primer sets (P-1 and P-2) derived from the IS 900 fragment, it was possible to detect MAP in a manner similar to that used with nested PCR. The sensitivity of LAMP with P-1 was 0.5 pg/tube, which was more sensitive than nested PCR. When P-2 was used, 5 pg/tube could be detected, which was the same level of sensitivity as that for nested PCR. LAMP with P-1 was specific. Although only 2 Mycobacterium scrofulaceum strains out of 43 non-MAP mycobacterial strains were amplified, the amplification reaction for these strains was less efficient than for MAP strains, and their products could be distinguished from MAP products by restriction digestion. LAMP with P-2 resulted in very specific amplification only from MAP, the same result obtained with nested PCR. Our LAMP method was highly specific, and the white turbidity of magnesium pyrophosphate, a by-product of the LAMP reaction, allowed simple visual detection. Our method is rapid, taking only 2 h, compared with 4 h for nested PCR. In addition, the LAMP method is performed under isothermal conditions and no special apparatus is needed, which makes it more economical and practical than nested PCR or real-time PCR. These results indicate that LAMP can provide a rapid yet simple test for the detection of MAP.

The changes in ganglioside composition of bovine erythrocytes associated with Theileria sergenti infection were investigated using the erythrocytes before and after the infection. The erythrocytes before infection with T. sergenti had GM3, sialosylparagloboside (SPG), i-active, and I-active ganglioside as predominant gangliosides. After infection with T. sergenti merozoites, the contents of SPG and i-active ganglioside were slightly less, and I-active ganglioside content was much less in the erythrocytes, though GM3 content did not so vary. The decreased I-active ganglioside content showed a recovery as the parasitemia waned to low level in the infected cattle. The total amount of lipid-bound sialic acid also decreased in the erythrocytes after the infection. Similar changes were also caused by the incubation of liposomes containing ganglioside fraction obtained from bovine erythrocytes with T. sergenti piroplasms. These results suggest that the reduction of the contents of SPG, i-active, and I-active ganglioside on the erythrocytes was related to the T. sergenti infection.

A pair of synthetic oligonucleotide primers, designed from the gene encoding a 32-kDa intraerythrocytic piroplasm surface protein of Theileria sergenti, were used to amplify parasite DNA from the blood of T. sergenti-infected cattle by means of the polymerase chain reaction (PCR). PCR-amplified DNA was examined by electrophoresis and by dot blot or microplate hybridization using a parasite-specific cDNA probe. PCR was specific for T. sergenti, since no amplification was detected with DNA from Anaplasma centrale, Babesia ovata, uninfected erythrocytes, and leukocytes. This method was sensitive enough to detect about 4.5 parasites per microliters of blood with a 10-microliters sample volume. Moreover, of 66 specimens from grazing cattle, 40 were microscopically positive, whereas PCR revealed that 54 samples were positive. Therefore, PCR provides a useful diagnostic tool for detecting T. sergenti-infected cattle, and it is significantly more sensitive than the current methods.

In this study, the plasma glucose concentrations of cows carrying a somatic cell clone fetus during late pregnancy and placental glucose transporter (GLUT) mRNA levels at parturition were examined. Parturition was induced using dexamethasone, prostaglandin F(2α) and estriol in cows bearing a clone (Clone) or a fetus fertilized in vivo as a control (DEX). Plasma glucose concentrations were measured in the cows (days 257 and 271 of pregnancy and at parturition) and newborn calves. Cotyledon and caruncle tissues removed just after parturition were used for mRNA extraction. Expression of mRNA was also analyzed in control cows that were induced to undergo parturition without dexamethasone (PG) or that spontaneously delivered (SP). The glucose concentrations of the Clone group were significantly low at all points examined, but those of the calves were normal. The increase in the maternal glucose concentration from day 257 to parturition was significantly lower in the Clone group. Glucose concentrations were negatively correlated with birth weight for clones (day 257; r=-0.584, day 271; r=-0.286, parturition; r=-0.549). There was no difference in mRNA levels in the cotyledons among the animals examined. In the caruncles, the Clone and PG groups showed significantly higher GLUT1 and GLUT3 mRNA levels than the SP group, and the GLUT3 mRNA level was significantly higher in the Clone group than in the DEX group. The glucocorticoid receptor α mRNA level was significantly lower in the SP group than in the DEX group. Although spontaneous parturition and administration of dexamethasone suppressed the placental GLUT mRNA levels, the action was not observed in clone pregnancy. These results raise the possibility of facilitation of glucose transportation through the placenta to meet increased nutritional requirements of overgrown clone fetuses.

It has been assumed that the agent causing BSE in cattle is a uniform strain (classical BSE); however, different neuropathological and molecular phenotypes of BSE (atypical BSE) have been recently reported. We demonstrated the successful transmission of L-type-like atypical BSE detected in Japan (BSE/JP24 isolate) to cattle. Based on the incubation period, neuropathological hallmarks, and molecular properties of the abnormal host prion protein, the characteristics of BSE/JP24 prion were apparently distinguishable from the classical BSE prion and closely resemble those of bovine amyloidotic spongiform encephalopathy prion detected in Italy.

The present study was conducted to evaluate the effect of accessory sperm cells that adhered to the zona pellucida or blastomeres on the accuracy of genetic diagnosis of preimplantation embryos. The properties of sperm cells as a template for DNA amplification were examined using bovine sperm cells frozen-thawed or incubated in PBS after thawing for 7 days at 39 C. Sexing by loop-mediated isothermal amplification (LAMP) and claudin-16 genotyping by polymerase chain reaction (PCR) were performed using 10, 50 and 100 sperm cells. When sexing based on LAMP was performed, no amplified DNA was detected in 10 sperm-derived samples, whereas male-specific (10-60%) and gender-natural DNA (30-100%) sequences were detected in 50 and 100 sperm-derived samples. The detection rates for gender-natural DNA sequences were higher in incubated sperm samples than in sperm samples immediately after freeze-thawing. The detection rates for claudin-16 were low (7-13%) regardless of the concentration of sperm cells and the period of incubation after thawing. The present results showed that male-specific DNA, gender-natural DNA and claudin-16 sequences were not usually amplified from a small number of sperm cells (or =10 cells). However, when a large number of sperm cells (or =50 cells) were present, male-specific and gender-natural DNA sequences were amplified at a high rate, and claudin-16 DNA sequences were also occasionally detected. These results raise the possibility that accessory sperm cells may reduce the accuracy of the genetic diagnosis of bovine embryos. Therefore, steps to prevent the contamination of sperm cells, such as removal of the zona pellucida and washing of sample blastomeres, are necessary to obtain an accurate result.

The epigenetic reprogramming of the donor cell nucleus is an important factor in the development of embryos and production of normal offspring derived by somatic cell nuclear transfer (NT-SC). During early development, a dramatic reduction in methylation levels occurs in mouse. In early embryos, this process makes it possible to erase gamete-specific methylation patterns and induce de novo methylation at defined developmental time-points. To clarify changes in DNA methylation in bovine NT-SC embryos, we examined satellite I sequences in bovine embryos derived in vivo (Vivo) and by NT-SC at the blastocyst (BC) and elongated (EL) stages. Because the EL stage embryo consists of the embryo disc (ED) and trophectoderm (TE), the methylation status of each part was analyzed with respect to the progress of differentiation. DNA methylation levels in Vivo embryos were increased during the elongation stage. In contrast, DNA methylation levels in NT-SC embryos remained unchanged in the ED and significantly decreased in the TE. Real-time PCR analysis showed that Dnmt-1 expression in BC embryos derived by NT-SC was significantly lower than that in Vivo embryos; thus, differences in the DNA methylation status may reflect transcript levels of Dnmt-1. Our results suggest that the aberrant methylation level of bovine NT-SC embryos in the satellite I region is corrected as a result of demethylation and retention of methylation as the embryo develops and differentiates.

Fecal and nasal samples were collected from 180 calves with diarrhea and 36 clinically normal co-habitants, and tested for virus using HRT-18 cell cultures derived from human rectal adenocarcinoma. A cytopathic virus was isolated from 5 fecal and 56 nasal samples obtained from diarrheic calves. All calves in which the virus was isolated from diarrheic feces were positive for virus isolation from nasal swabs. The virus was also isolated from the nasal swabs of 10 clinically normal calves that were co-habitants with diarrheic calves. Because they were morphologically similar to coronavirus, agglutinated mouse erythrocytes and serologically identical with the Nebraska calf diarrhea coronavirus, new isolates were identified as bovine coronavirus. The demonstration of viral antigens in nasal epithelial cells by a direct immunofluorescence was in close agreement with the virus isolation in HRT-18 cell cultures. This is the first report on the isolation of bovine coronavirus from newborn calves with diarrhea in Japan. The evidence that the virus was frequently isolated from nasal swabs is of great interest for understanding the pathogenesis of bovine coronavirus infection.

The objective of this study was to determine changes in the transcription of insulin-like growth factor (IGF)-related genes in blastocyst (BC)- and elongated (EL)-stage embryos produced by nuclear transfer using somatic cells (NT-SC). Bovine BC (day 7)- and EL (day 15)-stage embryos were obtained from NT-SC or in vivo production (Vivo). The relative abundance of mRNA was examined by RT- real-time PCR. The transcript of IGF-II was only detected at the EL stage in both the NT-SC and Vivo embryos. The level of transcription of the IGF-I receptor (r) in the NT-SC embryos was decreased at the EL stage and was significantly (P

We attempted to apply an embryo sexing kit with Loop-mediated Isothermal Amplification (LAMP) to sex chromosomal chimerism analysis in heterosexual twin female calves. Peripheral blood was used for the amplification of male-specific DNA, derived from XY leukocytes. When blood samples were diluted 1:1000 in LAMP reaction mixture, hemoglobin or blood coagulation did not influence the turbidity measurement of the reaction mixture for detection of amplified DNA. This procedure detected the existence of XY leukocytes of 0.01% in female blood. Furthermore, all heterosexual twin female calves, bearing sex chromosomal chimerism based on karyotyping and PCR, showed male-specific DNA from peripheral blood by LAMP. These results indicated that the embryo sexing kit with LAMP was available for sensitive detection of sex chromosomal chimerism. This procedure made it possible to detect easily Y-chromosome specific DNA in a short interval compared with PCR, and was convenient for field application of freemartin diagnosis.

To assess relationships between nucleotide polymorphisms of the prion protein (PRNP) gene and susceptibility to bovine spongiform encephalopathy (BSE), we investigated polymorphisms in the open reading frame (ORF) and 2 upper regions of the PRNP gene from 2 Japanese cattle breeds: 863 healthy Holstein cattle, 6 BSE-affected Holstein cattle, and 186 healthy Japanese Black (JB) cattle. In the ORF, we found single-nucleotide polymorphisms (SNPs) at nucleotide positions 234 and 576 and found 5 or 6 copies of the octapeptide repeat, but we did not find any amino acid substitutions. In the upper region, we examined 2 sites of insertion/deletion (indel) polymorphisms: a 23-bp indel in the upper region of exon 1, and a 12-bp indel in the putative promoter region of intron 1. A previous report suggests that the 23-bp indel polymorphism is associated with susceptibility to BSE, but we did not find a difference in allele frequency between healthy and BSE-affected Holstein cattle. There were differences in allele frequency between healthy Holstein and JB cattle at the 23- and 12-bp indels and at the SNPs at nucleotide positions 234 and 576, but there was no difference in allele frequency of the octapeptide repeat. We identified a unique PRNP gene lacking a 288-bp segment (96 amino acids) in DNA samples stocked in our laboratory, but this deletion was not found in any of the 1049 cattle examined in the present study. The present results provide data about variations and distribution of the bovine PRNP gene.

Loop-mediated isothermal amplification (LAMP) is a novel DNA amplification method that amplifies a target sequence specifically under isothermal conditions. The objective of this study was to identify a Y chromosome-specific sequence in water buffalo and to establish an efficient procedure for embryo sexing by LAMP. The homologues of a Y chromosome-specific sequence, bovine repeat Y-associated.2, in swamp and river buffalo were cloned, and designated swamp buffalo repeat Y-associated.2 and river buffalo repeat Y-associated.2, respectively. Sexing by LAMP was performed using primers for swamp buffalo repeat Y-associated.2. A 12S rRNA was also amplified by LAMP as a control reaction in both male and female. The minimal amount of the template DNA required for LAMP appeared to be 0.1-10 pg. The sensitivity was further examined using swamp buffalo fibroblasts as templates. When fibroblasts were lysed with NaOH, the minimal cell number required for detection of both male-specific and male-female common DNA appeared to be two cells, whereas correct determination of sex could not be achieved using fibroblasts lysed by heat denaturation. Embryo sexing was also performed using blastomeres from interspecies nuclear transfer embryos. The sex determined by LAMP for blastomeres corresponded with the sex of nuclear donor cells in analyses using four or five blastomeres as templates. The LAMP reaction required only about 45 min, and the total time for embryo sexing, including DNA extraction, was about 1 h. In conclusion, the present procedure without thermal cycling and electrophoresis was reliable and applicable for water buffalo embryos.

The low efficiency of animal production using somatic cell nuclear transfer procedures is considered to be the result of an incomplete reprogramming of donor cell nucleus, which leads to abnormal expression of developmentally important genes. The objective of this study was to determine the abundance of gene transcripts of insulin-like growth factor (IGF)-related genes in cloned bovine embryos reconstructed with somatic cells. Single embryos derived from nuclear transfer reconstructed with somatic cells (NT-SC) or embryo blastomeres (NTEM), in vitro fertilization (IVF), in vivo production (Vivo), and parthenogenetic treatment (PA) were analyzed. The relative abundance of mRNA was examined by real-time PCR. Transcripts of the IGF-1 receptor (r) and IGF binding protein (BP)-2 were detected in all embryos, regardless of origin. IGF-IIr and IGFBP-3 transcripts signals in NT-SC embryos were detected with significantly lower frequencies of 25 and 50%, respectively. Although IGF-Ir and IGFIIr transcript levels were not significantly different in NT-SC, NT-EM, IVF, Vivo, and PA embryos, the relative abundance in individual embryos indicated large variation in NT-SC. IGFBP-2 and IGFBP-3 levels were high in the Vivo embryos compared with NT-SC, NT-EM, IVF, or PA embryos. These results suggest differences in levels of transcripts of IGF-related genes in the bovine embryos produced by NT compared with IVF, Vivo, and PA.

A rapid method to determine the allelic variants of the sheep PrP gene was developed. DNA samples from 128 Suffolk sheep (39 rams and 89 ewes) were screened by using polymerase chain reactions and dot-blot hybridization with 32P-labeled nine allele-specific oligonucleotide probes corresponding to the polymorphic PrP codons 112, 136, 154 and 171. Three allelic variants of the PrP gene, PrP(MARQ), PrP(TARQ) and PrP(MARR), were found in the flocks. Among those variants, nearly half of the ewes had alleles of the 171-Arg variant that is closely associated with resistance to natural scrapie. Assessments of allelic mutations of the PrP gene may help to select the scrapie-resistant progenitors in the flocks.

Theileria sergenti piroplasms were purified from different parasitemia peaks of cattle infected with parasitized erythrocytes or sporozoites during persistent infection. Their activities with monoclonal antibodies 13F5 and C9, which recognize 23 kDa and 32 kDa piroplasm surface proteins, respectively, were analyzed. Antigenic differences were observed among parasites from different parasitemia peaks during persistent infection when cattle were infected with sporozoites. Results of two-dimensional polyacrylamide gel electrophoresis showed that the 23 and 32 kDa proteins were expressed in all samples tested, regardless of their reactivities with the monoclonal antobodies. In contrast, parasites obtained from cattle inoculated with parasitized erythrocytes showed no antigenic alteration over a 2 month observation period. The results suggest that antigenic alteration of T. sergenti during persistent infection is related to whether the parasites proliferate through extraerythorocytic schizont stage in cattle or sporozoite and other sexual stages in tick vector.

To elucidate whether or not gangliosides on the bovine erythrocytes serve as a receptor for Theileria sergenti merozoites, the reactivities of the T. sergenti piroplasms with gangliosides were studied by the liposome agglutination test. The parasites reacted weakly with I-active ganglioside containing N-acetylneuraminic acid (NeuAc) and strongly with I-active ganglioside containing N-glycolylneuraminic acid (NeuGc). However, none of the other gangliosides expressed on the bovine erythrocytes, such as GM3 (NeuAc), GM3 (NeuGc), sialosylparagloboside (SPG) (NeuAc), SPG (NeuGc), i-active ganglioside (NeuAc), and i-active ganglioside (NeuGc), were recognized. After infection with T. sergenti, furthermore, the content of I-active ganglioside (NeuAc) was less (p0.05), and I-active ganglioside (NeuGc) content was much less in the erythrocytes (p0.01), though the contents of other NeuAc- and NeuGc-containing gangliosides did not so vary with T. sergenti infection. These results suggest that the parasites recognize the I-active ganglioside as their receptor and bind preferentially to NeuGc-carrying I-active ganglioside rather than to NeuAc-type in the target cell membranes, and that the reduction of the contents of I-active gangliosides (NeuAc and NeuGc) on the erythrocytes was related to T. sergenti infection.

Restriction fragment length polymorphisms (RFLPs) of Theileria sergenti DNA were analysed using probes of a genomic DNA fragment (pTs 2) and a cDNA corresponding to this genomic probe (C-Ts 2). Each of the probes detected RFLPs in DNA from different stocks of Theileria sergenti. Additionally, using these probes, alterations in hybridization patterns were observed in samples of the parasites harvested at different times after individual calves had been infected with Theileria sergenti. This result suggests that the Theileria sergenti stocks used were mixed parasite populations.

Background Prions, infectious agents associated with prion diseases such as Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE) in cattle, and scrapie in sheep and goats, are primarily comprised of PrPSc, a protease-resistant misfolded isoform of the cellular prion protein PrPC. Protein misfolding cyclic amplification (PMCA) is a highly sensitive technique used to detect minute amounts of scrapie PrPSc. However, the current PMCA technique has been unsuccessful in achieving good amplification in cattle. The detailed distribution of PrPSc in BSE-affected cattle therefore remains unknown. Methodology/Principal Findings We report here that PrPSc derived from BSE-affected cattle can be amplified ultra-efficiently by PMCA in the presence of sulfated dextran compounds. This method is capable of amplifying very small amounts of PrPSc from the saliva, palatine tonsils, lymph nodes, ileocecal region, and muscular tissues of BSE-affected cattle. Individual differences in the distribution of PrPSc in spleen and cerebrospinal fluid samples were observed in terminal-stage animals. However, the presence of PrPSc in blood was not substantiated in the BSE-affected cattle examined. Conclusions/Significance The distribution of PrPSc is not restricted to the nervous system and can spread to peripheral tissues in the terminal disease stage. The finding that PrPSc could be amplified in the saliva of an asymptomatic animal suggests a potential usefulness of this technique for BSE diagnosis. This highly sensitive method also has other practical applications, including safety evaluation or safety assurance of products and byproducts manufactured from bovine source materials.

ホルスタイン種の泌乳牛8頭を供試し,牧草サイレージ及びとうもろこしサイレージの給与量が養分摂取量,乳量及び乳組成にどのような影響を及ぼすかについて検討を行った.試験処理は,A)牧草サイレージ,B)牡草サイレージ+とうもろこしサイレージ15kg,C)牧草サイレージ+とうもろこしサイレージ30kg,D)とうもろこしサイレージ,の4区で,チモシーサイレージ(出穂期収穫)をA,B,C区で自由に摂取させ,とうもろこしサイレージ(黄熟期収穫)はA,B,C区でそれぞれ0,15,30kgを,D区では自由に摂取させた.また,全牛に1日2kgの乾草と乳量の1/5の濃厚飼料を給与した.その結果,次のような知見を得た.サイレージ総乾物摂取量及びTDN摂取量は,とうもろこしサイレージの給与量が増加するにしたがって上昇する傾向を示したが,DCP摂取量は,とうもろこしサイレージの多給によ低下する傾向を示した.実乳量及びFCM量は,牧草サイレージの単独給与区が最も低く,特にFCM量においては,他のとうもろこしサイレージ給与区に比して有意(P