QTLs affecting kernel size and shape in a two-rowed by six-rowed barley cross.

The suitability of barley ( Hordeum vulgare L.) grain for malting depends on many criteria, including the size, shape and uniformity of the kernels. Here, image analysis was used to measure kernel size and shape attributes (area, perimeter, length, width, F-circle and F-shape) in grain samples of 140 doubled-haploid lines from a two-rowed (cv Harrington) by six-rowed (cv Morex) barley cross. Interval mapping was used to map quantitative trait loci (QTLs) affecting the means and within-sample standard deviations of these attributes using a 107-marker genome map. Regions affecting one or more kernel size and shape traits were detected on all seven chromosomes. These included one near the vrs1 locus on chromosome 2 and one near the int-c locus on chromosome 4. Some, but not all, of the QTLs exhibited interactions with the environment and some QTLs affected the within-sample variability of kernel size and shape without affecting average kernel size and shape. When QTL analysis was conducted using data from only the two-rowed lines, the region on chromosome 2 was not detected but QTLs were detected elsewhere in the genome, including some that had not been detected in the analysis of the whole population. Analysis of only the six-rowed lines did not detect any QTLs affecting kernel size and shape attributes. QTL alleles that made kernels larger and/or rounder also tended to improve malt quality and QTL alleles that increased the variability of kernel size were associated with poor malt quality.

Diversity of Salmonella serotypes in cull (market) dairy cows at slaughter.

OBJECTIVE: To determine the diversity of Salmonella serotypes isolated from a large population of cull (market) dairy cows at slaughter. DESIGN: Cross-sectional study. SAMPLE POPULATION: Salmonella organisms isolated from the cecal-colon contents of 5,087 market dairy cows. PROCEDURE: During winter and summer 1996, cecal-colon contents of cull dairy cows at slaughter were obtained from 5 US slaughter establishments. Specimens were subjected to microbiologic culturing for Salmonella spp at 1 laboratory. Identified isolates were compared with Salmonella isolation lists published by the Centers for Disease Control and Prevention (CDC) and the National Veterinary Services Laboratory (NVSL) for approximately the same period. The Simpson diversity index was used to calculate the likelihood that Salmonella isolates selected randomly by establishment were different. RESULTS: Of 58 Salmonella serotypes identified, Salmonella ser. Montevideo was the most prevalent. Two of the top 10 CDC serotypes identified from in 1996, Salmonella ser. Typhimurium and S Montevideo, appeared on our top 10 list; 8 of the top 10 were found on NVSL listings. Thirty-one of 59 S. Typhimurium isolates were identified as DT104 and found at a west slaughter establishment, 30 during the winter and 1 during the summer. The greatest diversity of serotypes was at a southeast establishment during the summer; the least diversity was at a central establishment in the winter. CONCLUSIONS AND CLINICAL RELEVANCE: 58 Salmonella serotypes were isolated from market dairy cows at slaughter and could pose a threat for food-borne illness. Salmonella Montevideo was the most frequently isolated serotype and may contribute substantially to salmonellosis in dairy cattle.

Prevalence of Salmonella spp in cull (market) dairy cows at slaughter.

OBJECTIVE: To determine the prevalence of Salmonella spp in the cecal-colon contents of cull (market) dairy cows at slaughter because of potential public health ramifications. DESIGN: Survey study. SAMPLE POPULATION: Cecal-colon contents collected from 5,087 cull (market) dairy cows at slaughter at 5 slaughter establishments across the United States. PROCEDURE: During 2 periods of the year, winter (January and February) and summer (July through September), 5 cull (market) cow slaughter establishments in the United States--west (WE), southeast (SEE), central (CE), north central (NCE), and south central (SCE)--establishments were visited, and cecal-colon contents of cull dairy cows were obtained at the time of slaughter. Samples were examined by microbiologic culture at a single laboratory for Salmonella spp. RESULTS: Salmonella spp were detected in 23.1% of cecal-colon content samples from cull dairy cows across the 5 slaughter establishments. The highest site prevalence (54.5%) was detected at the WE during the summer period, whereas the lowest was found at the CE during the summer (4.3%) and at the NCE during the winter (4.5%). Considerable variation in the daily prevalence of Salmonella spp was found, particularly at the WE and the SCE. Salmonella spp were isolated from 93% of cecal-colon contents collected on a summer day at the WE. CONCLUSIONS AND CLINICAL RELEVANCE: Results strongly suggest that there is a high prevalence of Salmonella spp in cull dairy cows at slaughter, which could burden Hazard Analysis Critical Control Point programs implemented in slaughter establishments. Procedures to reduce Salmonella load at the dairy farm and during transport to slaughter could reduce the risk of spread during the slaughter process.

The educational implications of reproductive problems identified during investigations at Michigan dairy farms.

This study constitutes the review of 44 dairy herd investigations that were initiated because of complaints relating to decreased reproductive efficiency. Each investigation was conducted at the request of the veterinary practitioner who provided the routine reproductive examinations and consultations at the farm. Thus the types of problems identified were those not resolved by routine veterinary care and management practices. A total of 4.5, 27.3 and 31.8% of the farms, respectively, failed to keep reproductive records, failed to maintain accurate records on events such as breeding dates, or failed to evaluate available summary reports with the local veterinary practitioner. Of the 44 farms, 50.0, 38.6, 54.5 and 11.4%, respectively, reported problems related to estrus detection rate, number of days to first service (for reasons other than estrus detection), conception rate and early embryonic death. Within each of these reproductive parameters specific problems were defined and discussed. Reproductive inefficiency was found to be most commonly associated with ineffective estrus detection and decreased conception rate. Most importantly, farm managers and employees frequently misunderstood the relationship between the accuracy of estrus detection and the conception rate (61.4% of the farms). We therefore identified factors which have an impact on dairy herd reproductive efficiency to suggest topics for training programs for producers and practicing veterinarians as well as for elective courses for veterinary students in the area of theriogenology.

Comparative study of the knowledge, attitudes, and behaviors of large animal veterinarians, dairy farmers, and dairy processors in Michigan on bovine somatotropin.

A cross-sectional epidemiologic study was conducted to evaluate two objectives. The first was to determine the knowledge, attitudes, and behaviors of large animal (dairy) veterinarians, dairy farmers, and dairy processors in Michigan toward the use of bovine somatotropin (BST). The second was to compare and contrast the data from the large animal veterinarians, dairy farmers, and dairy processors according to the knowledge, attitude, and behavior variables. A written questionnaire was used as an instrument to collect data relating to the objectives. Three basic types of questions were asked of each group: (1) how much do you know about BST? (knowledge-based question), (2) how do you feel about BST? (attitude-based question), and (3) how would you use BST or use dairy products produced through BST biotechnology (behavior-based question)?

N-acetyl-beta-D-glucosaminidase as a predictor of milk loss and recovery after clinical mastitis.

Milk samples were collected at onset of 508 episodes of clinical mastitis on a 1,700-cow dairy farm in Michigan. Daily milk production and disease events were recorded for all cows in the herd. Despite statistical association with severity of mastitis, this association was too weak for N-acetyl-beta-D-glucosaminidase (NAGase) activity to be of great value as a prognostic test for clinical mastitis. High milk NAGase activity was significantly (P less than 0.0001) associated with: increased duration of treatment; increased duration of clinical signs of mastitis; decreased daily milk production; and increased risk of the cow being culled because of mastitis. The NAGase value was combined with days in milk production, baseline milk production before mastitis onset, parity, and season of onset to predict the outcome of clinical cases as measured by the first 3 aforementioned variables. Statistical models explained little of the variability among cows in duration of treatment (R2 = 0.11), duration of clinical signs of infection (R2 = 0.11), and milk production change (R2 = 0.09).

Whole blood quality assurance control samples for forensic toxicology.

Pilot studies were undertaken to examine the feasibility of preparing freeze-dried whole blood samples containing drugs of interest to be used as assay controls. The availability of such samples will enable analysts and laboratory managers to monitor analytical performance. A pilot batch of freeze-dried blood containing five compounds of forensic significance and a blank blood sample were prepared for reconstitution to 2.5-mL aliquots. Samples of each of these preparations were distributed to 55 laboratories in the USA and UK for analysis. A summary of the results is presented along with comments on the feasibility of producing freeze-dried whole blood samples for use in forensic toxicology.

The effect of age at calving on reproduction, milk production and disease incidence in the first lactation of dairy heifers.

Herd health and production records of 1161 Holstein-Friesian heifers from 22 Michigan dairy herds were utilized to study the effect of age at first calving upon reproductive efficiency, milk production and the incidence of disease in the first lactation. Age at first calving was not significantly related to either milk production or reproductive efficiency. Heifers displaying dystocia were significantly older at calving than those that calved without problems. Additionally, the incidence of ketosis was associated with a significantly greater age at first calving. Heifers with diarrhea and those that aborted were significantly younger at calving than their herdmates. Incidence of 12 other common dairy diseases was not related to age at first calving. It would, therefore, appear that the dairy producers we studied could inseminate their heifers at an earlier age, and thereby increase production per day of life, without suffering serious detrimental effects in lactational milk production, reproductive efficiency or overall disease incidence.

DNA-binding factors of B lymphoid cells are susceptible to limited proteolytic cleavage during nuclear extract preparation.

DNA-binding proteins that interact with the 3' end of the mouse mu immunoglobulin heavy chain gene were identified by the electrophoretic mobility shift assay. Complexes of distinctly different mobilities were formed by extracts prepared from B lymphoid lines representing different stages of maturation. The apparent stage-specific differences are shown to be due to proteolytic events that occurred during extract preparation.

Analysis of delta mRNA in the immature B lymphocytes of neonatal liver and spleen.

The production of mu m and delta m mRNA was assessed by measuring the relative levels of the two species in nuclear RNA isolated from neonatal liver and from spleen cells obtained from mice of differing ages. These analyses showed that the lack of IgD expression in the immature B cells of neonatal liver is due to an absence of delta mRNA. The presence of high mol. wt species which hybridize to a delta probe indicates that the delta coding regions are transcribed and suggest that post-transcriptional events account for the lack of delta expression. Little change in the mu m-delta m mRNA ratio was observed in nuclear RNA isolated from spleen cells of mice aged from 5 days to 4 months. Thus, variations in the levels of mRNA synthesis play an insignificant role in the changes in IgM and IgD expression seen during B cell maturation in neonatal spleen.

Descriptive epidemiology of anestrus in Michigan Holstein-Friesian cattle.

Twenty-two Michigan Holstein-Friesian herds were studied to determine the incidence and epidemiology of anestrus. In 3,309 lactations studied, 42% were classified as having exhibited preservice anestrus (no estrus detected by 70 d after calving). Organic reasons (pyometra, cystic follicles, static ovaries) were identified by palpation per rectum for 237 (23%) of the cows with preservice anestrus that were examined by a veterinarian. Postservice anestrus, defined as failure to show estrus within 35 d after an unsuccessful insemination, was identified in 790 (47%) of 1,691 lactations. Veterinary examination identified 104 (20%) of postservice anestrous cows as having this condition because of organic causes. The average cow with preservice anestrus had an increase of 30 d open compared to her herdmates, and the average cow with postservice anestrus had an increase of 37 d open. Anestrous cows produced more milk than their unaffected herdmates in both the current and the previous lactation. Analysis of composite lactation curves indicates that, for preservice anestrus, this additional milk production was obtained gradually over the entire lactation. Anestrous cows were culled at a significantly higher rate than their herdmates. Cows with preservice anestrus were more likely to have begun their lactation in the spring months.

Repeated insemination in Michigan Holstein-Friesian cattle: Incidence, descriptive epidemiology and estimated economic impact.

Twenty-two Michigan dairy herds participating in a computerized herd-health program were studied to determine the incidence and epidemiologic characteristics of repeat-breeder syndrome. A cow with repeat-breeder syndrome was defined as having been inseminated three or more times within the same lactation. Repeat-breeder syndrome was observed in 24% of 3,309 lactations. Cost components associated with unsuccessful inseminations included costs of delayed conception, extra inseminations, extra veterinary service and losses due to culling. Lactations with repeat-breeder syndrome were associated with a loss of approximately $385. An estimated extra cost of $140 was associated with a second insemination, $279 with three inseminations, $429 with four inseminations and $612 with five inseminations.

Mode of regulation of immunoglobulin mu- and delta-chain expression varies during B-lymphocyte maturation.

The transcription, processing, and accumulation of mu and delta mRNA was studied in several cell lines representing different stages of B-lymphocyte maturation. Our results indicate that the relative content of mu and delta mRNA is the major determinant of the IgM versus IgM + IgD phenotype and that the production of delta mRNA is regulated at distinctly different levels of gene expression in early and later developmental stages. In B cell lymphomas typical of early stages, transcription extends over the entire 25 kb of the mu- delta locus and the relative content of mu and delta mRNA is determined at the level of mRNA processing. In contrast, in cells typical of mature IgM secretors, transcription is terminated abruptly between the mu and delta genes, precluding the production of delta mRNA. We propose a model that accounts for qualitative and quantitative changes in mu-delta expression in the developing B lymphocyte.

Lipopolysaccharide-induced transcription of the kappa immunoglobulin locus occurs on both alleles and is independent of methylation status.

The transcriptional activity of the kappa immunoglobulin genes in a B-cell lymphoma line, 7OZ/3 was measured before and after stimulation by lipopolysaccharide (LPS). Analyses of accumulated nuclear RNA components and of nascent transcripts showed that LPS induces transcription of both the productively rearranged (kappa+) and the unrearranged (kappa) allele in these cells. This pattern of transcriptional activation correlates well with the LPS induced appearance of a DNAase I hypersensitive site on both alleles in the vicinity of a putative enhancer element (Parslow and Granner, Nucl. Acids Res. 11, 4775, 1983). However, the transcriptional activation is not accompanied by detectable hypomethylation at Hha I and Hpa II sites which are normally undermethylated when kappa genes are constitutively expressed. These findings have enabled us to evaluate the relative importance of various structural parameters to the transcriptional competence of the kappa locus.

Methylation status and DNase I sensitivity of immunoglobulin genes: changes associated with rearrangement.

Immunoglobulin V kappa genes are transcriptionally silent in their germline context and become transcriptionally active upon fusion to the J kappa-C kappa region (kappa locus). To elucidate the role of chromosomal structure in this regulatory phenomenon we have investigated the DNase I sensitivity and methylation status of the kappa locus and selected V kappa genes in a variety of alleles exhibiting different rearrangement configurations and different levels of transcriptional activity. Our findings indicate that the kappa locus in either germline or rearranged contexts maintains a distinctive DNase I-sensitive, hypomethylated structure in plasmacytomas and hybridomas, irrespective of its level of transcriptional activity. In contrast, the germline V kappa genes are in less accessible regions of chromatin and more highly methylated regions of DNA. Upon fusion to the kappa locus, V kappa genes become DNase I-sensitive and hypomethylated. This effect extends several kilobases upstream of the transcriptional initiation site but does not extend to the adjacent V kappa gene or to the identical V kappa allele on the other chromosome, indicating that the structural alteration is a localized cis-acting phenomenon.

Transcription of the unrearranged mouse C kappa locus: sequence of the initiation region and comparison of activity with a rearranged V kappa-C kappa gene.

In cells of the B-lymphocyte lineage, 8.4 kb transcripts are constitutively produced from unrearranged kappa constant region (kappa 0) loci. To help elucidate the molecular basis of this phenomenon, we have determined the nucleotide sequence surrounding the site of transcriptional initiation. The kappa 0 transcripts are initiated within a unique Eco RI fragment located about 8 kb upstream from the C kappa gene. The start site is about 36 nucleotides downstream from a Hogness consensus sequence (TGTAAAT) and nearly 200 nucleotides upstream from a sequence that is similar to those encoding the signal peptides of kappa light chains. These features, which are usually found in the 5' flanking regions of kappa variable region genes, suggest that the kappa 0 initiation sequence may be an evolutionary relic of some common ancestral 5' element. In contrast, there is no discernible V kappa-encoding element in 780 nucleotides of sequence downstream from the initiation site. From pulse-chase-labeling experiments with a pre-B-cell hybridoma line and direct measurements of transcriptional activity in isolated nuclei, we have estimated that the rate of transcription of the kappa 0 locus is significantly lower than that of a rearranged V kappa-C kappa gene. This result, together with the fact that unrearranged V kappa genes are transcriptionally silent, suggests that structural features of both the V kappa and C kappa loci contribute to the overall transcriptional efficiency of a rearranged V kappa-C kappa gene. The 8.4 kb transcripts are not processed into any stable RNA products, despite the fact that they contain some apparently normal splice junctions; rather, they are degraded within the nucleus at about half the rate with which a kappa mRNA precursor is processed. Conceivably, the transcriptional activity of the kappa 0 locus might be a prerequisite for its recombinatorial activity.