Bacterial community analysis of purulent material from liver abscesses of crossbred cattle and Holstein steers fed finishing diets with or without tylosin

Liver abscesses in feedlot cattle are polymicrobial infections. Culture-based studies have identified Fusobacterium necrophorum as the primary causative agent, but a number of other bacterial species are frequently isolated. The incidence of liver abscesses is highly variable and is affected by a number of factors, including cattle type. Holstein steers raised for beef production have a higher incidence than crossbred feedlot cattle. Tylosin is the commonly used antimicrobial feed additive to reduce the incidence of liver abscesses. The objective of this study was to utilize 16S ribosomal RNA amplicon sequence analyses to analyze the bacterial community composition of purulent material of liver abscesses of crossbred cattle (n = 24) and Holstein steers (n = 24), each fed finishing diet with or without tylosin. DNA was extracted and the V3 and V4 regions of the 16S rRNA gene were amplified, sequenced, and analyzed. The minimum, mean, and maximum sequence reads per sample were 996, 177,070, and 877,770, respectively, across all the liver abscess samples. Sequence analyses identified 5 phyla, 14 families, 98 genera, and 102 amplicon sequence variants (ASV) in the 4 treatment groups. The dominant phyla identified were Fusobacteria (52% of total reads) and Proteobacteria (33%). Of the top 25 genera identified, 17 genera were Gram negative and 8 were Gram positive. The top 3 genera, which accounted for 75% of the total reads, in the order of abundance, were Fusobacterium, Pseudomonas, and Bacteroides. The relative abundance, expressed as percent of total reads, of phyla, family, and genera did not differ (P > 0.05) between the 4 treatment groups. Generic richness and evenness, determined by Shannon–Weiner and Simpson’s diversity indices, respectively, did not differ between the groups. The UniFrac distance matrices data revealed no clustering of the ASV indicating variance between the samples within each treatment group. Co-occurrence network analysis at the genus level indicated a strong association of Fusobacterium with 15 other genera, and not all of them have been previously isolated from liver abscesses. In conclusion, the culture-independent method identified the bacterial composition of liver abscesses as predominantly Gram negative and Fusobacterium as the dominant genus, followed by Pseudomonas. The bacterial community composition did not differ between crossbred and Holstein steers fed finishing diets with or without tylosin.     

Genetic Variation for Maize Epicuticular Wax Response to Drought Stress at Flowering

Drought stress is thought to promote epicuticular wax accumulation on maize leaves, which reduces plant water loss. We evaluated 62 maize inbred lines and their hybrid testcross progeny for epicuticular wax accumulation on flag leaves at flowering under full and limited irrigation regimes. Extracted wax was measured as a percentage of wax weight to leaf weight (WLW) and leaf area (WLA). Eleven genotypes had above average WLW as both inbred lines and hybrid testcrosses. Thirteen genotypes had above average WLA as either inbred lines or hybrid testcrosses. The drought treatment did not significantly alter WLW or WLA. Heritability of WLW was 0.17 (inbred lines) and 0.58 (hybrid testcrosses). Heritability of WLA was 0.41 (inbred lines) and 0.59 (hybrid testcrosses), suggesting it is a better trait than WLW for epicuticular wax screening. Correlations (r) between inbred lines and their testcross progeny were 0.44 and 0.18, for WLW and WLA, respectively. Heritability of grain weight per ear and plot yield was highest in hybrid testcrosses, with no correlation between inbred and hybrid germplasm. It is not warranted to evaluate epicuticular wax accumulation as the sole drought tolerance mechanism. However, it may be a good secondary trait to observe in relation to grain yield production in hybrids tested under water‐limiting conditions.     

Predicting percentage of intramuscular fat using two types of real-time ultrasound equipment

In the present study, 500 steers were used to develop models for predicting the percentage of intramuscular fat (PIMF) in live beef cattle. Before slaughter, steers were scanned across the 11th and 13th ribs using Aloka 500V (AL-500) and Classic Scanner 200 (CS-200) machines. Four to five images were collected per individual steer using each machine. After slaughter, a cross-sectional slice of the longissimus muscle from the 12th rib facing was used for chemical extraction to determine actual carcass percentage of intramuscular fat (CPIMF). Texture analysis software was used by two interpreters to select a region for determination of image parameters, which included Fourier, gradient, histogram, and co-occurrence parameters. Four prediction models were developed separately for each of AL-500 and CS-200 based on images captured by the respective machines. These included models developed without transformation of CPIMF (Model I), models based on logarithmic transformation of CPIMF (Model II), ridge regression procedure (Model III), and principal component regression procedure (Model IV). Model R2 and root mean square error of AL-500 Models I, II, III, and IV were 0.72, 0.84%; 0.72, 0.85%; 0.69, 0.91%; and 0.71, 0.86%; respectively. The corresponding R2 and root mean square error values of CS-200 Models I, II, III, and IV were 0.68, 0.87%; 0.70, 0.85%; 0.64, 0.94%; and 0.65, 0.91%; respectively. Initially, AL-500 and CS-200 prediction models were validated separately on an independent data set from 71 feedlot steers. The overall mean bias, standard error of prediction, and rank correlation coefficient across the four AL-500 models were 0.42%, 0.84%, and 0.88, respectively. For the four CS-200 models, the corresponding overall mean values were 0.67%, 0.81%, and 0.91, respectively. In a second validation test, only Model II of AL-500 and CS-200 was evaluated separately based on data from 24 feedlot steers. The overall mean bias, absolute difference, and standard error of prediction of AL-500 Model II were 0.71, 0.92, and 0.98%. For CS-200 Model II, the corresponding values were 0.59, 0.97, and 1.03%. Both AL-500 and CS-200 equipment can be used to accurately predict PIMF in live cattle. Further improvement in the accuracy of prediction equations could be achieved through increasing the development data set and the variation in PIMF of cattle used.     

Cavity Formation in Thin Films of Viscous Liquids

High-speed photography was utilized to observe the dynamic growth behavior of a cavity in a viscous liquid. From these observations it has been shown that a relatively elementary analytical approach will reproduce the general cavity growth characteristics.     

Use of positive contrast rhinography and intranasal sinography for diagnosis of a nasofacial sinus tract in a dog

Twelve days after a dog fight, a 2-year-old sexually intact female Bulldog was evaluated because of subcutaneous emphysema of increasing severity throughout the dogs body. Thoracic radiography revealed severe pneumomediastinum from which free air had extended into the retroperitoneal space, resulting in pneumoperitoneum. Tracheoscopic examination did not reveal a discontinuity of the trachea, pharynx, or larynx. A breach between the nasal cavity and subcutaneous tissues of the nasal region was suspected. Further diagnostic investigations included positive contrast rhinography and intranasal sinography. Via an angiographic catheter inserted into the left naris, positive contrast intranasal sinography revealed a sinus tract extending between the left nasal cavity and the subcutaneous tissue of the dorsal aspect of the nasal planum. Resolution of subcutaneous emphysema, pneumomediastinum, and pneumoretroperitoneum began 1 day after surgical closure of the intranasal opening of the sinus tract. To the authors' knowledge, this radiographic technique has not been reported.     

Sperm Morphology in the Domestic Cat, and its Relation with Fertility: A Retrospective Study

Knowledge about normal ranges in semen quality and the association between sperm morphology and fertility in felids is limited. The aims of this retrospective study were to (1) define a normal spermiogram in cats; (2) evaluate possible effects of season, age and breed on sperm morphology; and (3) evaluate the relationship between sperm morphology and fertility. Semen samples collected by electroejaculation from 52 cats were evaluated for sperm morphology. The cats constituted two groups: a general population of cats (n = 48) and cats examined because of poor breeding records (n = 4). The general population was divided into household (n = 20), pedigree (n = 19) and colony cats (n = 9) and into three age classes, <12 months, 12-59 months and >or=60 months. The median percentage of normal spermatozoa in the general population was 44.0% (range 1.0-91.0%). Criteria were tentatively set for what was considered a normal spermiogram. The mean percentage of normal spermatozoa was higher during February to July than during August to January (p < 0.05). Pedigree cats had a lower mean percentage of normal spermatozoa than did household cats (p < 0.05). Age had no effect on the percentage of normal spermatozoa but was positively correlated with the percentage of proximal droplets. Of the cats with <40% normal spermatozoa (n = 19), all those with known breeding records (n = 11) had produced litters. The four cats examined because of poor breeding results had higher percentages of different sperm abnormalities than tentatively stipulated for the normal spermiogram. In two of these cats both sperm morphology and fertility changed over time.