Mechanisms of Infertility Associated with Clinical and Subclinical Endometritis in High Producing Dairy Cattle

Clinical and subclinical endometritis are common causes of infertility and subfertility in high producing dairy cattle, delaying the onset of ovarian cyclic activity after parturition, extending luteal phases and reducing conception rates. Escherichia coli and Arcanobacterium pyogenes cause endometrial damage and inflammation. Components of microbes, such as lipopolysaccharide (LPS), are detected by Toll-like receptors on endometrial cells, leading to secretion of cytokines, chemokines and antimicrobial peptides. Long luteal phases associated with endometritis are probably caused by a switch in endometrial prostaglandin production from prostaglandin F_2a (PGF) to prostaglandin E₂. In addition, LPS impairs the function of the hypothalamus and pituitary, and directly perturbs ovarian granulosa cells steroidogenesis, providing mechanisms to explain the association between uterine disease and anovulatory anoestrus. Cows with uterine disease that ovulate have lower peripheral plasma progesterone concentrations that may further reduce the chance of conception associated with endometritis.     

Indirect magnetic resonance lymphography of the head and neck of dogs using Gadofluorine M and a conventional gadolinium contrast agent: A pilot study

The purpose of this pilot study was to evaluate lymph node enhancement with an indirect magnetic resonance (MR) lymphography technique using 2 different contrast agents in the head and neck region of healthy dogs. Five dogs were imaged at various times after intradermal injection of gadoversetamide and Gadofluorine M (minimum of 1 week apart) in the right and left mandibular, temporal, and lateral neck regions. We observed consistent progressive enhancement with time in the mandibular, retropharyngeal, and superficial cervical lymph nodes. The node enhancement was comparable for both contrast agents. Contrast enhancement of the parotid lymph nodes was not seen. We conclude that this technique of indirect MR lymphography using either agent could be used to identify those lymph nodes at highest risk of metastatic disease in dogs with cancer, and to guide staging and treatment.     

非晶态木质纳米纤维素机械特性的建模

为提高对以木纤维为填充材料的复合材料的理解和性能分析,对木质纳米纤维素中的非晶态结构进行分子建模与拉伸变形仿真研究.通过对纳米纤维素非晶态结构进行周期性边界条件建模,在能量最小化和热平衡后,基于ReaxFF力场用开源代码程序LAMMPS对模型进行拉伸变形仿真,模拟原子间的相互作用,对其数据结果采用MATLAB进行后处理分析,并采用可视化开源软件Atomeye对变形过程进行监控.通过所建模型仿真研究数据,可以计算得到木质纳米纤维素纳观尺度的机械特性,求得纳观结构中应力一应变曲线,将其同实验数据相比较,用于预测材料宏观尺度各特性以及本构关系.该研究为今后分析高分子聚合物和纤维素的纳米微观界面相容性打下基础,能更好地理解高分子纤维聚合材料的力学性能.     

Genetic parameters for Oviposition time and interval in a white leghorn population of recent commercial origin

1. Heritabilities and phenotypic and genetic correlations were estimated for oviposition time and interval as well as for conventional measures of egg production in a White Leghorn population of recent commercial origin. Oviposition times were recorded under both a normal light‐dark cycle (NL) and continuous light regime (CL).

2. The heritabilities for oviposition interval, 0.54 in NL and 0.52 in CL, were much higher than those for egg number or rate of lay and the genetic correlation between intervals in the two lighting environments was 0.82, suggesting some interaction between genotype and lighting regimen.

3. The genetic correlations between mean oviposition interval in either environment and conventional measures of egg production were all high and negative and, together with the above heritability estimates, suggested a possible advantage of oviposition interval as a selection criterion for improvement of egg production.

4. In NL, mean and standard deviation of oviposition times showed moderate to high heritabilities and high genetic correlations with oviposition interval, as expected from their close physiological relations.     

Increase in Oviposition interval due to the sex‐linked dwarf gene in white leghorns and Australorps

1. Oviposition patterns in dwarf and normal pullets were compared after the dw gene had been introduced into a White Leghorn and an Australorp strain, which had been selected for reduced oviposition interval.

2. The dw gene increased oviposition interval by about 2 h and reduced clutch length by two‐thirds in both strains. It also decreased the occurrence of intervals shorter than 21 h and of membranous and soft‐shelled eggs in the White Leghorn strain, but had little effect on these traits in the Australorp. About two‐thirds of the 17% difference in rate of lay between dwarf and normal pullets could be attributed to the difference in oviposition interval.

3. It is suggested that the dw gene may be useful in overcoming certain physiological barriers when selecting for shorter oviposition interval.     

21世纪世界家禽科学研究与发展方向

家禽界在２１世纪的目标与挑战是满足全世界人们对动物蛋白的需求。解决这一问题的关键是需要生产更多的饲料粮－谷类、油子、荚豆类，给日益增长的家禽提供额外的饲料。在过去５０年里，已发生了很多改变；（１）２０世纪世界上５０％的人从家禽技术革命 中获益。（２）近年在遗传学、营养学、动物保健、舍饲及管理技术方面的提高，期待在生产中得到广泛应用。（３）目前在分子生物学、营养学、保健及繁殖方面的研究将在未来更广泛     

Design of diverter berms for soil erosion control and biorestoration along pipeline rights-of-way

Abstract Diverter berms are used to control soil erosion along restored pipeline corridors between the time the pipe is installed and the establishment of a vegetation cover. Current practice, based on standard design procedures, is often inadequate in areas of steep slopes and erosive rainfall because the resulting berm channels are too steeply graded and too widely spaced, and insufficient attention is given to their outlets. The Universal Soil Loss Equation provides a more flexible procedure for determining the spacing required to achieve a specified erosion target for given conditions of rainfall, soils and slopes. Where the required spacings are not feasible because they are too close, spacings should be based on ensuring that flow velocity does not exceed 80% of the maximum non-eroding velocity, and additional supporting erosion-control measures should be provided. Channels should be graded at 0.4% and the grade should never exceed 2%. The choice of type of outlet should be determined by the erodibility of the soil, the steepness of the slope, vegetation cover and whether the outlet slope is on undisturbed or made-up ground. Broad-based berms should be used as an alternative to narrow-based ones where there is a risk of damage from vehicles.