Molecular epidemiological analysis of Mycoplasma bovis isolates from the Pennsylvania Animal Diagnostic Laboratory showing genetic diversity

We have examined the genetic variability of Mycoplasma bovis strains submitted to the Pennsylvania Animal Diagnostics Laboratory, University Park (PA-ADL), between December 2007 and December 2008. Of 4,868 total samples submitted for Mycoplasma testing, 302 were determined to be culture positive. Mycoplasma bovis (63.6%), Mycoplasma californicum (7.3%), Mycoplasma bovirhinis (2.7%), Mycoplasma bovigenitalium (0.7%), Mycoplasma alkalescens (4.9%), Mycoplasma putrefaciens (0.3%), and Mycoplasma dispar (1.3%) and unidentified Mycoplasma sp. (19.2%) were identified using PCR. Mycoplasma bovis represented the largest portion of the positive samples submitted. Each of the 192 M. bovis isolates was examined for variations in the BglII and MfeI restriction sites of the DNA using amplified fragment length polymorphism fingerprinting and subsequently compared with the M. bovis type strain PG45 (ATCC 25523). Similarity between strains was calculated using the Dice similarity coefficient, which ranged from approximately 0.7 to 1.0. When clustering the isolates at greater than 95% similarity, it was determined that 11 distinct clusters were present. The results are consistent with the existence of at least 2 clonally distinct groups. No clear geographical, month of isolation, or source origination relationship was identified, indicating that a currently unclassified characteristic is responsible for the strain heterogeneity. These data indicate strong heterogeneity of M. bovis isolates submitted to PA-ADL. Additionally, multiple sites throughout Pennsylvania had isolates of separate clonal lineages present concomitantly, indicating the ability of multiple overlapping outbreaks to occur at a single location. Mycoplasma bovis represents the largest portion of Mycoplasma species isolated from PA-ADL samples. We propose that amplified fragment length polymorphism may serve as a valuable tool for molecular characterization of M. bovis strains from the United States.     

Short communication: evidence for a major gene by polygene interaction for milk production traits in German Holstein dairy cattle

The present study investigated putative interaction effects between the DGAT1 K232A mutation and the polygenic term (i.e., all genes except DGAT1) for 5 milk production traits in the German Holstein dairy cattle population. Mixed models were used, and the test for interaction relied on the comparison of polygenic variance components depending on the sire's genotypes at DGAT1 K232A. Substitution effects were highly significant for all traits. Significant interaction effects were found for milk fat and protein percentage.     

Short communication: statistical models for the analysis of coagulation traits using coagulating and noncoagulating milk information

Aims of this study were to propose statistical models for the analysis of rennet coagulation time (RCT) suitable for making use of coagulating and noncoagulating (NC) milk information, to estimate heritabilities and to obtain rank correlations for sire merit. A total of 1,025 Holstein cows (progeny of 54 sires) reared in 34 herds were milk-sampled once. Data were analyzed using 4 alternative models: a standard linear (SLM), a right-censored linear Gaussian (CLM), a survival (SUM), and a threshold (THM) model. Model SLM analyzed coagulated milk records only, whereas analysis with CLM or SUM considered information of NC samples as censored records. Model THM analyzed occurrence of milk coagulation as a dichotomous trait. An artificial censoring scenario with an endpoint at 18 min (SET18) was considered after the rearrangement of the timeframe originally used for the observation of RCT (SET31). Heritabilities ranged from 0.12 to 0.25. Correlations of sire rankings ranged from 0.23 to 0.92. Differences in sire rankings between SLM and CLM or SUM increased when the proportion of NC records increased. Correlations between sire rankings obtained for SET31 and SET18 were high for CLM and SUM, indicating that rankings provided by these models tended to be stable even when a large fraction of samples with observed RCT was re-classified as NC milk. Results indicate that CLM and SUM are more suitable than SLM and THM for the analysis of coagulation ability when data contain NC milk information.     

Methane emissions from dairy cows measured using the sulfur hexafluoride (SF6) tracer and chamber techniques

Our study compared methane (CH₄) emissions from lactating dairy cows measured using the sulfur hexafluoride (SF₆) tracer and open-circuit respiration chamber techniques. The study was conducted using 16 lactating Holstein-Friesian cows. In each chamber, the cow was fitted with the SF₆ tracer apparatus to measure total CH₄ emissions, including emissions from the rectum. Fresh ryegrass pasture was harvested daily and fed ad libitum to each cow with a supplement of 5 kg of grain/d. The CH₄ emissions measured using the SF₆ tracer technique were similar to those using the chamber technique: 331 vs. 322 g of CH₄/d per cow. The accuracy of the SF₆ tracer technique was indicated by considering the ratio of the CH₄ emission measured using the SF₆ tracer to the emission measured using the chamber for each cow on each day. The calculated ratio of 102.3% (SE = 1.51) was not different from 100%. A higher variability within cow between days was found for the SF₆ tracer technique [coefficient of variation (CV) = 6.1%] than for the chamber technique (CV = 4.3%). The variability among cows was substantially higher than within cows, and was higher for the SF₆ technique (CV = 19.6%) than for the chamber technique (CV = 17.8%). Our CH₄ emission data were compared with whole-animal chamber studies conducted in Canada and Ireland. In the Canadian study the SF₆ technique did not measure CH₄ emissions from the rectum and emissions were 8% lower than those measured using the chamber, indicating that emissions from the rectum may be greater than previously measured (1%). The relationship between CH₄ emission and dry matter intake was examined for our data and for that reported in the Canadian study. There was a difference in the slopes of the regressions derived from our data and that from Canada; 17.1 vs. 20.8 g of CH₄/kg of dry matter intake. A difference between the 2 locations was expected based on the difference in diet composition for these 2 studies. The SF₆ tracer technique is reasonably accurate for inventory purposes and for evaluating the effects of mitigation strategies on CH₄ emissions.     

剖白湿皮制作黄牛软面革工艺

本文讨论了采用白湿皮工艺生产黄牛软面革的主要技术措施，并对复鞣、加脂剂进行了筛选。     

Prediction of daily and lactation yields of milk, fat, and protein using an autoregressive repeatability test day model

We evaluated the accuracy of an autoregressive multiple-lactation test day (ATD) model to predict missing test day yields of milk, fat, and protein to obtain cumulative 305-d records for cows with incomplete or in-progress lactations. The data consisted of more than one million observations of daily yields on test days in the first 3 lactations of over 75,000 Portuguese Holstein cows. Differences between actual (estimates from complete lactations using the test interval method) and ATD-predicted 305-d yields were negligible and smaller than those predicted by the test interval method. The ATD procedure tended to slightly underestimate cumulative lactation yields, whereas the test interval method substantially overestimated them. Smaller differences obtained by the ATD procedure resulted in less biased estimates of lactation yield, which also implies greater accuracy. As expected, the correlations between actual and predicted lactation yields increased with the number of test days from 0.831 to 0.997. Average correlations (by parity) between actual and ATD-predicted yields ranged from 0.977 to 0.984. Correlations between actual test day yields and corresponding predicted yields exceeded 0.5 for up to 7 time-intervals from the last test day yield used to predict cumulative yield of projected lactations. These correlations indicate the good predictive ability of the ATD method. From a producer's viewpoint, these advantages underwrite management because most on-farm selection decisions are based on the producing abilities of cows. Implementation of ATD methodology does not require special computing capability and is easily transferable to the farm level.     

Meat quality of Nguni steers supplemented with Acaciakarroo leaf-meal

The objective of the study was to determine the meat quality of Nguni steers supplemented with Acaciakarroo leaf-meal. Thirty 19-month old steers were randomly assigned to A.karroo leaf-meal (AK), sunflower cake (SF) and a control (CN) diets. Steers on the AK and SF diets were given an additional 150 g of protein per day for 60 days. The steers were slaughtered at 21 months and the m.longissimusthoracisetlumborum was sampled for meat quality measurements. Steers that received SF diet had lighter-coloured (L*) (P < 0.05) meat than those on AK and CN diets. The highest redness (a*) (17.3 ± 0.29) values were recorded in steers supplemented with AK compared to those that received SF and CN diets. Diet had no effect on pH, drip loss, water holding capacity, sarcomere length, muscle bundle areas, myofibrillar fragment length, Warner–Bratzler shear force and cholesterol values. Steers supplemented with AK (22.4 ± 0.08%) and SF (22.5 ± 0.08%) had higher (P < 0.05) meat protein content than those on the CN (20.2 ± 0.08%) diet. Highest muscle fibre area (3472.6 ± 119.51 μm²), fat content (1.2 ± 0.11%) and cooking loss (25.2 ± 0.73%) of meat aged for 2 days were recorded in steers given the SF diet compared to those on the AK and CN diets. Supplementing Nguni cattle with A.karroo leaf-meal produced beef of comparable quality to natural pasture alone but with a fresher appearance and higher protein content.     

鲁西黄牛皮组织结构的研究

采用组织显微切片技术对鲁西黄牛皮组织结构进行了研究。研究结果表明，鲁西黄牛皮的特点是毛细、毛孔小，张幅大，皮板较厚，乳头层薄，网状层厚，汗腺、肌肉、弹性纤维较发达，网状层胶原纤维束粗大，编织较紧密，皮内毛根底部毛球，少数呈钩形状，脂腺不甚发达，没有游离脂肪细胞，但皮下组织内脂肪细胞较多。因此．在生产过程中应加强机械去肉，采用缓和的碱膨胀，适当加强酶软化和复鞣填充处理，以制得优质的黄牛皮轻革。     

Preparation of ceramic foams suitable for aircraft arresting by the airport runway based on a protein foaming agent

Crushable ceramic foams are more suitable to be used as an arrestor material applied in engineered materials arresting system(EMAS) for airport runway for their properties of widely controllable strength, negligible crushing-rebounding behavior, durability, and chemically-inert composition, comparing with traditional concrete foams. The synthesis of ceramic foams adopted direct-foaming method and used an animal protein as foaming agent. Kaolin, talc powder and alumina were the main raw materials. Effects of the ratios of raw materials, calcination temperatures, heating rates, holding time, viscosities of polyvinyl alcohol(PVA) solution as well as the amounts of protein foaming agent and water on microscopic structure, densities, compressive strength and open porosities of ceramic foams were investigated systematically. The results indicate that ceramic foams with typical pore sizes 100-300 μm, open porosities from 73.1% to 91.5%, densities from 0.25 to 0.62 g·cm-3, compressive strength from 0.19 to 4.89 MPa, are obtained by properly adjusting the parameters mentioned above. And the mechanical strength meets the requirement for the EMAS for airport runway. In addition, good correlations are observed among compressive strength, open porosity, microscopic structure, and crystal phase. Furthermore, the possibility of producing the general dimensions of such aircraft arresting components with the proposed method was also discussed.     

Cattle and Amblyomma variegatum Odors Used in Host Habitat and Host Finding by the Tick Parasitoid, Ixodiphagus hookeri

The response of mated naive Ixodiphagus hookeri females to cattle and Amblyomma variegatum nymphal odors was tested in a Y-tube olfactometer. I. hookeri females were attracted to cattle urine, dung, and odors from tick-free feeding sites of A. variegatum nymphs on cattle, e.g., dewlaps, front heels, and hind heels. Tick-free scrotal odors did not attract the parasitoids. Furthermore, odors from off-host unfed and fed A. variegatum nymphs did not attract the parasitoids, despite an increase in the number of the nymphs to amplify any odor signal. A blend of odors from feeding on-host nymphs and cattle scrota attracted the parasitoids. In T-tube bioassays, I. hookeri females were attracted to hexane washes and fecal extracts of A. variegatum nymphs.