Virginia Agricultural Experiment Station

Laboratory equipment and techniques which have been developed for the production of highly reduced media and for the handling and inoculation of large numbers of fastidiously anaerobic bacteria are described. With these techniques over 150 cultural and biochemical characteristics have been routinely determined on several hundred strains of anaerobes with a minimum of effort.

Evidence that lecithin, rather than butter fat, may be the constituent of milk affected when oxidized flavor develops, was presented in the first of this series of studies on oxidized flavor (7). In continuing a study of the probable relation of lecithin to oxidized flavor development it was considered that processes which disturb the adsorbed layers on the fat globules might have some effect on the susceptibility of the milk to the development of this flavor.

SummaryShading cv Biscoe peach scaffold limbs 30–40, 35–45 and 40–50 days after full bloom (AFB) caused greater fruit abscission than shading from 15–25, 20–30, 25–35 or 50–60 days AFB. Terbacil, applied to peach limbs at 400 ppm thinned fruit at a similar timing as shading (35 and 40 days AFB). Whole tree airblast sprays of terbacil (300 ppm) applied 35 days AFB to cv Redhaven peach trees induced fruit abscission, but c. 25 % of the leaves showed marginal yellowing at harvest. Flower buds were produced at the nodes of leaves bearing symptoms. Shading of cv Starkrimson Delicious limbs from 16–26 days AFB caused significant fruit abscission. Shading 6–16, 26–36 and 36–46 days AFB did not induce fruit drop. Terbacil (400 ppm) applied to limbs at 6 and 16 days AFB significantly reduced fruit set, but applications 26 and 36 days AFB were ineffective. Whole tree airblast applications of terbacil (200 ppm) defruited spur cv Delicious trees when applied 16 days AFB. Limb treatments of terbacil at rates twice those of the airblast treatments caused much less fruit abscission. No leaf symptoms were observed with the airblast treatments (200 ppm), but some yellowing of leaves occurred on the limb treatments that were applied with a hand sprayer to the point of drip at 400 ppm. Apple and peach fruit from shaded or terbacil-thinned limbs or trees were similar or larger than from hand thinned.

Shading (92%) of `Redchief Delicious' apple (Malus domestics Borkh.) trees for 10-day periods from 10 to 20, 15 to 25, 20 to 30, and 25 to 35 days after full bloom (DAFB) caused greater fruit abscission than shading from 5 to 15, 30 to 40, 35 to 45, or 47 to 57 DAFB. Fruit 8 to 33 mm in diameter (10 to 30 DAFB) were very sensitive to 10 days of shade, even though fruit sizes of 6 to 12 mm are considered the most sensitive to chemical thinners. In a second test, shading for 3 days caused fruit thinning; 5 days of shade in the periods 18 to 23, 23 to 28, and 28 to 33 DAFB caused greater thinning than 11 to 16 or 33 to 38 DAFB. Shading reduced photosynthesis (Pn) to about one-third that of noncovered trees. Terbacil (50 mg·liter -1 ) + X-77 surfactant (1250 mg·liter -1 ) applied with a hand-pump sprayer 5, 10, or 15 DAFB greatly reduced fruit set and caused some leaf yellowing, particularly in the earliest treatments. Terbacil reduced Pn by more than 90% at 72 hours after application. Shoot growth of trees defruited by shade or terbacil was equivalent to defruited or deblossomed trees; ethephon (1500 mg·liter -1 ) inhibited tree growth and defruited trees. No terbacil residues were dectected in fruit at harvest from applications made 5, 15, 20, 25, or 30 DAFB. Eleven of 12 photosynthesis-inhibiting herbicides were also found to thin `Redchief Delicious' apple trees. Shading caused more thinning than terbacil at the later applications, which may reflect poorer absorption and/or lesser photosynthetic inhibition than when terbacil was applied to older leaves.

Effect of density and size of particles on their rate of passage through the digestive tract of cattle and humans was estimated with inert plastic particles. The particles that passed most rapidly had a density of about 1.2 gm./cm2 and a size of 20 to 30 10 -8 cm. ~ Editor.

Abstract Corn was harvested for silage at soft, medium, and hard dough and fed ad libitum to three groups of lactating Holstein cows (six per group) as the only forage in two trials. Each trial consisted of two periods. During one period cows received soybean meal as the only supplemental feed. Concentrate mixture (containing 16% crude protein) was fed at 1lb per 3.5lb milk during the other period. Dry matter content of the respective maturities averaged 25.4, 30.3, and 33.3%. Milk yields increased significantly with dry matter content of the silages. Dry matter intakes of silage were significantly increased with advancing maturity and were probably responsible for the higher production. Differences due to maturity were greatest when cows were supplemented with only soybean meal. No significant effect due to maturity of silage was noted in milk composition, body weight gains, efficiency of milk production, or TDN content of silage dry matter.

The ability to detect a specific organism from a complex environment is vitally important to many fields of public health, including food safety. For example, tomatoes have been implicated numerous times as vehicles of foodborne outbreaks due to strains of Salmonella but few studies have ever recovered Salmonella from a tomato phyllosphere environment. Precision of culturing techniques that target agents associated with outbreaks depend on numerous factors. One important factor to better understand is which species co-enrich during enrichment procedures and how microbial dynamics may impede or enhance detection of target pathogens. We used a shotgun sequence approach to describe taxa associated with samples pre-enrichment and throughout the enrichment steps of the Bacteriological Analytical Manual's (BAM) protocol for detection of Salmonella from environmental tomato samples. Recent work has shown that during efforts to enrich Salmonella (Proteobacteria) from tomato field samples, Firmicute genera are also co-enriched and at least one co-enriching Firmicute genus (Paenibacillus sp.) can inhibit and even kills strains of Salmonella. Here we provide a baseline description of microflora that co-culture during detection efforts and the utility of a bioinformatic approach to detect specific taxa from metagenomic sequence data. We observed that uncultured samples clustered together with distinct taxonomic profiles relative to the three cultured treatments (Universal Pre-enrichment broth (UPB), Tetrathionate (TT), and Rappaport-Vassiliadis (RV)). There was little consistency among samples exposed to the same culturing medias, suggesting significant microbial differences in starting matrices or stochasticity associated with enrichment processes. Interestingly, Paenibacillus sp. (Salmonella inhibitor) was significantly enriched from uncultured to cultured (UPB) samples. Also of interest was the sequence based identification of a number of sequences as Salmonella despite indication by all media, that samples were culture negative for Salmonella. Our results substantiate the nascent utility of metagenomic methods to improve both biological and bioinformatic pathogen detection methods.

The objective of this study was to determine intake and site and extent of nutrient digestion of lactating cows grazing pasture with or without energy supplementation. Four dual-cannulated (rumen and proximal duodenum) cows were randomly assigned to two groups to graze mixed cool season grass legume pasture with either no supplement or with 6.4 kg of cracked corn and mineral mix daily in a switchback design with three 2-wk periods. Markers (Cr2O3 and Co-EDTA) were used to estimate intake, duodenal flow, fecal output, and fractional rates of passage from the rumen. Daily OM intake was similar between diets, but OM intake of pasture was lower when cows were fed corn. Apparent OM and NDF digestibilities in the rumen and total digestive tract were lower when cows were supplemented with corn than when they consumed pasture only. Supplemental corn decreased ruminal NH3 N (22 vs. 17 mg/dl) and increased N recovery at the duodenum (86% vs. 75% of N intake). Nonammonia, nonmicrobial N flowing to the duodenum was 67% of the total NAN flow. Corn increased energy intake of grazing cows, but decreased herbage intake and digestibility.

RANK ANALYSIS OF INCOMPLETE BLOCK DESIGNS: III. SOME LARGE-SAMPLE RESULTS ON ESTIMATION AND POWER FOR A METHOD OF PAIRED COMPARISONS Get access RALPH ALLAN BRADLEY RALPH ALLAN BRADLEY Virginia Agricultural Experiment Station of the Virginia Polytechnic Institute Search for other works by this author on: Oxford Academic Google Scholar Biometrika, Volume 42, Issue 3-4, December 1955, Pages 450–470, https://doi.org/10.1093/biomet/42.3-4.450 Published: 01 December 1955

IN RECENT years there has been considerable interest in the effects of crowding on broiler production. Tomhave and Seegar (1945) found that decreased floor space resulted in lower body weight, increased mortality and poorer feed conversion. Heishman et al. (1952) reported no significant differences in the number of culls, mortality, cannibalism or dressed quality as area was reduced from 1.0 to 0.5 square foot per bird, but body weights were reduced as population density increased. Although viability was good in New Hampshires and crossbreds, Hartung (1955) noted a reduction in “Grade A” carcasses in more concentrated flocks. Siegel and Coles (1958) found no significant differences in the weights or feed conversions of broilers grown at floor space levels ranging from 0.5 to 1.25 square feet per bird. It seems probable that much of the contradictory nature of these reports may be the result of differences in genetic stock and management …

Our national data and infrastructure security issues affecting the ‘bioeconomy’ are evolving rapidly. Simultaneously, the conversation about cybersecurity of the U.S. food and agricultural system (cyberbiosecurity) is incomplete and disjointed. The food and agricultural production sectors influence over 20% of the nation’s economy ($6.7T) and 15% of U.S. employment (43.3M jobs). The food and agricultural sectors are immensely diverse and they require advanced technologies and efficiencies that rely on computer technologies, big data, cloud-based data storage, and internet accessibility. There is a critical need to safeguard the cyberbiosecurity of our bioeconomy, but currently protections are minimal and do not broadly exist across the food and agricultural system. Using the food safety management Hazard Analysis Critical Control Point system concept as an introductory point of reference, we identify important features in broad food and agricultural production and food systems: dairy, food animals, row crops, fruits and vegetables, and environmental resources (water). This analysis explores the relevant concepts of cyberbiosecurity from food production to the end product user (such as the consumer) and considers the integration of diverse transportation, supplier and retailer networks. We describe common challenges and unique barriers across these systems and recommend solutions to advance the role of cyberbiosecurity in the food and agricultural sectors.

SUMMARY The present study of the fermentation characteristics of 20 species of clostridia has shown that the relative proportions and concentrations of the acids and alcohols produced by these cultures may be very useful in their characterization and identification. The chromatographic methods described are rapid and the patterns are highly reproducible among strains of the same species.

FOR many years the results of our experimental work with Escherichia coli seemed to lack the consistency that we desired. At times the same inoculum given to different groups of birds resulted in varying numbers of birds with pericarditis. Healthy uninoculated birds were raised in many batteries in an isolated building. When needed, birds were placed in the experimental cages from one or more batteries. Frequently birds from several battery sources remained in small experimental cages for from 1–7 days before being exposed to E. coli. Davis and Reed (1958) infected two groups of mice with Trickinella spiralis. The individuals in one group were isolated in individual cages while the others were allowed to fight in small groups for 4 hrs. daily. Isolated mice had fewer mature trichina than those which were allowed to fight. Newcomer (1958) found that chickens which were stressed by shaking or restraint had an…

DURING the past few years it has been observed that the usual chronic respiratory disease of chickens (CRD) and infectious sinusitis (IS) of turkeys has been complicated by fibrinous periphepatitis, pericarditis, and aerosacculitis. Losses when this complication occurs range from less than one to over 40 percent and many birds become difficult to finish for market. The disease can occur in any age group but usually occurs between 6 and 11 weeks of age. Salpingitis, peritonitis and hypopyon have been observed in association with the pericarditis. Wasserman et al. (1954) reported that Escherichia coli was isolated from 22 of 22 birds with pericarditis. Of 14 attempts at virus isolation from these cases, infectious bronchitis virus (IBV) was isolated from nine; the CRD agent from two, Newcastle disease virus (NDV) from one, and two were negative. Fahey (1955) reports that various bacteria and other diseases are associated with this condition. Pericarditis …

Records of 572 straightbred and crossbred matings of Angus, Hereford and Shorthorn cattle, collected over a 5-year period, were analyzed by least squares procedures to estimate the amount of heterosis from breed crosses. This procedure adjusted calf measurement data for the environmental effects of sex, year and age of dam (year, age of dam and parity were completely confounded), as well as for age in the case of weaning weight. The number of cows exposed to mating varied from 118 during the first season to 112 during the last season. The most important finding was a 10% advantage in calves weaned from crossbred matings, indicating heterosis for fertility and livability. There was evidence of heterosis in birth weight, preweaning growth rate and weaning weight. Feeder grade at weaning was slightly but not significantly lower among the crossbred calves. Differences existed among breeds in maternal environment in some breed combinations for growth rate, weaning weight and feeder grade at weaning.

BACKGROUND: Contamination of tomatoes by Salmonella can occur in agricultural settings. Little is currently understood about how agricultural inputs such as pesticide applications may impact epiphytic crop microflora and potentially play a role in contamination events. We examined the impact of two materials commonly used in Virginia tomato agriculture: acibenzolar-S-methyl (crop protectant) and copper oxychloride (pesticide) to identify the effects these materials may exert on baseline tomato microflora and on the incidence of three specific genera; Salmonella, Xanthomonas and Paenibacillus. RESULTS: Approximately 186 441 16S rRNA gene and 39 381 18S rRNA gene sequences per independent replicate were used to analyze the impact of the pesticide applications on tomato microflora. An average of 3 346 677 (634 892 974 bases) shotgun sequences per replicate were used for metagenomic analyses. CONCLUSION: A significant decrease in the presence of Gammaproteobacteria was observed between controls and copper-treated plants, suggesting that copper is effective at suppressing growth of certain taxa in this class. A higher mean abundance of Salmonella and Paenibacillus in control samples compared to treatments may suggest that both systemic and copper applications diminish the presence of these genera in the phyllosphere; however, owing to the lack of statistical significance, this could also be due to other factors. The most distinctive separation of shared membership was observed in shotgun data between the two different sampling time-points (not between treatments), potentially supporting the hypothesis that environmental pressures may exert more selective pressures on epiphytic microflora than do certain agricultural management practices.

Abstract Varying amounts of lactose were fed to 24 male Holstein calves (six per group) from 3 to 77 days of age. Rations were: 1) Hay-grain (after weaning from whole milk at 5 wk); 2) whole milk; 3) whole milk plus 5% lactose (on a milk weight basis); and 4) whole milk plus 15% lactose. At biweekly intervals animals were fasted 14 hr and blood glucose responses to ingestion of lactose (2 g/lb body weight) were determined. Calves were sacrificed at 11 wk, small intestines were removed, separated from contents, and divided into three equal-length sections for determination of lactase activities. Total digestible nutrients required per pound of gain and incidence of diarrhea were highest for calves on high lactose (Group 4). Increases in blood glucose resulting from lactose ingestion were also greater for this group (particularly at 9 and 11 wk). Lactase activity (mg glucose released/g intestinal protein) in the proximal third of the small intestine amounted to 876, 1,399, 1,881, and 2,012 for the respective treatments. Even greater differences among treatments were noted for total lactase due to the direct relationship between dietary lactose and intestinal tissue protein.

Feeding trials were carried out to determine the influence of N. P and K fertilization on the intake, digestibility and palatability of Kentucky 31 tall fescue hay. The fertilized hays were fed to sheep in either a conventional trial, with digestibility determined at the ad libitum level, or under a cafeteria system, where the animals had a free choice of the different hays. In the conventional trials level of N fertilizer had a significant effect on protein digestibility in both the first and aftermath cuttings. There were no differences in dry matter or cellulose digestibility between fertilized and control treatments in the first cutting, but a significant depression in digestibility in the non-nitrogen fertilized aftermath hays was noted. Ad libitum intake levels for the fescue hays were not significantly different in either cutting, and intake and NVI values were generally lower than for a standard alfalfa. When the first-cutting hays were offered to sheep on a cafeteria basis, the animals showed a decided, and individual ability to discriminate among treatments. The sheep tended to select either one or two major choices and to maintain this selection pattern fairly consistently over a 40-day period. Individuals differed in their feeding behavior, but as a group the primary selection was for fescue treated with phosphate fertilizer, and the second selection was for fescue fertilized at a low (50 lb.) level of nitrogen. The sheep tended to reject the fescue hays fertilized with medium and high levels of nitrogen. While significant differences in preference patterns or palatability due to fertilizer treatment were obtained, these differences appeared to bear no consistent relationship to intake as determined in the conventional system. An attempt was made to relate intake and palatability values to chemical composition, rates of in vitro fermentation and production of VFA from the forages. Differences in ad libitum intake between the fescues and alfalfa were associated with differences in structural components, more particularly with the cell-wall and lignin fractions. These differences were also reflected in the rates of breakdown of cellulose under in virto conditions. The phosphate-fertilized fescue hay was degraded at a significantly faster rate during the early stages of fermentation than the other fescue hays. Molar ratios of VFA determined in rumen fluid from sheep in the conventional trials showed no significant changes due to fertilizer treatment, but the acetic:propionic acid ratio in rumen fluid from sheep on a standard alfalfa was markedly lower. Intake and NVI values showed a significant negative correlation with the acetic:propionic acid ratio in rumen fluid. Little explanation can be offered for the observed differences in palatability. Variations in the level of carbohydrate, nitrogen and mineral components of the experimental hays were not related consistently to selection behavior. There was some indication of a sub-optimum level of phosphorus nutrition in the cafeteria animals, but the theory of “nutritional compensation” which is suggested requires further investigation.

Multiparous Holstein cows (n = 24) were fed diets containing 34 or 41% ruminally undegradable protein (RUP) for 30 d before parturition; then each group was fed a basal diet supplemented with or without ruminally stable Met (10.6 g/d) and Lys (15.2 g/d) for 75 d in the subsequent lactation. Supplementation of Met and Lys increased the milk yield of cows previously fed the low RUP diet, but milk yields before and after amino acid (AA) supplementation were similar for cows previously fed the high RUP diet. Milk protein content (percentage) increased from 2.83 to 2.96 for cows previously fed the high RUP diet. Milk protein yield increased from 1.13 to 1.21 kg/d when Met and Lys were fed. Data on AA concentration in plasma and AA extraction by the mammary gland suggest that the supplementation of Met and Lys corrected a Met limitation. According to the Cornell Net Carbohydrate and Protein System, the lactation diet was limiting for Met for maximum milk yield and was corrected by AA supplementation. Based on limiting AA, allowable milk yield was 42.5 kg/d, and the observed yield was 40.9 kg/d averaged across treatments. The group with the greatest allowable milk yield (45.2 kg/d) had the greatest actual milk yield (43.0 kg/d). The regression equation of observed milk yield on allowable milk yield was Y = 3.4 + 0.8805X.

The purpose of this study was to evaluate the influence of age, sex, and season of birth of calf, and age of dam on the preweaning growth rate and type score of Virginia beef calves. The study included 6,173 calves, divided into two groups for analysis. One group included 4,166 non-creep-fed calves and the other included 2,007 creep-fed calves. The data were pooled over a four-year period (1953–1956, inclusive) and over 44 Angus, 19 Hereford, and 3 Shorthorn herds. The data were arranged into sets of normal equations, and least squares estimates of the various effects were computed. No significant differences were apparent in the growth rate of non-creep-fed calves from 90 to 210 days of age. There was a slight decline from 211 to 240 days and a rather sharp decline after 240 days. Creep-fed-calves under 150 and over 240 days of age appeared to be at a greater disadvantage than non-creep-fed calves in those same age groups. Type scores were not influenced sufficiently by age of calf to be of any practical importance. Sex of calf influenced growth rate significantly in both the creep-fed and non-creep-fed groups but had little effect on type score. Bull calves grew approximately 5% faster than steer calves, and steer calves grew approximately 8% faster than heifer calves. Season of birth had a significant influence on growth of non-creep-feed calves, but was of no practical importance on growth of creep-fed calves or type score in either group. Age of dam was the most important source of variation studied with the largest differences occurring among the younger age groups. Maximum production was obtained from cows in the six- to ten-year-old age group. The reliability of the estimates was checked by applying them to the performance records of 3,147 non-creep-fed calves weighed in 1957. They were found to be satisfactory for equalizing sub-class means.