The effect of left displacement of abomasum corrected by toggle-pin suture on lactation,reproduction, and health of Holstein dairy cows

Our objectives were to evaluate the effect of left displacement of abomasum (LDA) after correction by toggle-pin suture (TPS) on lactation performance, reproduction and health in Holstein dairy cows in a commercial dairy farm. Cows diagnosed with LDA and corrected by the TPS procedure (188 cows) during the first 70 d postpartum were matched with control herd-mates (186 controls) according to lactation number, calving date, and previous lactation 305-d mature equivalent milk yield. Cows were grouped according to parity and days in milk and fed the same total mixed ration throughout a 321-d lactation. Data collected included yields of milk and 3.5% fat-corrected milk (FCM), concentration and yields of milk fat, somatic cell count, incidence of mastitis, abortion, death and culling, in addition to reproductive measures. Cows affected with LDA corrected by the TPS procedure produced less milk and tended to produce less 3.5% FCM than control cows, but the decrease in production occurred only during the first 4 mo of lactation. Left displacement of abomasum did not affect the interval from calving to conception and conception rates, but it extended the period from calving to first postpartum artificial insemination. Incidences of abortions and mastitis were not influenced by LDA. Cows affected with LDA remained in the study for a shorter period than their control herdmates, and higher proportions of cows with LDA were sold or died. Death and culling were more pronounced immediately after the diagnosis of LDA and the TPS procedure.     

Effect of interval between induction of ovulation and artificial insemination (AI) and supplemental progesterone for resynchronization on fertility of dairy cows subjected to a 5-d timed AI program

Objectives were to investigate 2 intervals from induction of ovulation to artificial insemination (AI) and the effect of supplemental progesterone for resynchronization on fertility of lactating dairy cows subjected to a 5-d timed AI program. In experiment 1, 1,227 Holstein cows had their estrous cycles presynchronized with 2 injections of PGF_2α at 46 and 60 d in milk (DIM). The timed AI protocols were initiated with GnRH at 72 DIM, followed by 2 injections of PGF_2α at 77 and 78 DIM and a second injection of GnRH at either 56 (OVS56) or 72 h (COS72) after the first PGF_2α of the timed AI protocols. All cows were time-inseminated at 72 h after the first PGF_2α injection. Pregnancy was diagnosed on d 32 and 60 after AI. In experiment 2, 675 nonpregnant Holstein cows had their estrous cycles resynchronized starting at 34 d after the first AI. Cows received the OVS56 with (RCIDR) or without (RCON) supplemental progesterone, as an intravaginal insert, from the first GnRH to the first PGF_2α. Pregnancy diagnoses were performed on d 32 and 60 after AI. During experiment 2, subsets of cows had their ovaries scanned by ultrasonography at the first GnRH, the first PGF_2α, and second GnRH injections of the protocol. Blood was sampled on the day of AI and 7 d later, and concentrations of progesterone were determined in plasma. Cows were considered to have a synchronized ovulation if they had progesterone <1 and >2.26 ng/mL on the day of AI and 7 d later, respectively, and if no ovulation was detected between the first PGF_2α and second GnRH injections during resynchronization. In experiment 1, the proportion of cows detected in estrus at AI was greater for COS72 than OVS56 (40.6 vs. 32.4%). Pregnancy per AI (P/AI) did not differ between OVS56 (46.4%) and COS72 (45.5%). In experiment 2, cows supplemented with progesterone had greater P/AI compared with unsupplemented cows (51.3 vs. 43.1%). Premature ovulation tended to be greater for RCON than RCIDR cows (7.5 vs. 3.6%), although synchronization of the estrous cycle after timed AI was similar between treatments. Timing of induction of ovulation with GnRH relative to insemination did not affect P/AI of dairy cows enrolled in a 5-d timed AI program. Furthermore, during resynchronization starting on d 34 after the first AI, supplementation with progesterone improved P/AI in cows subjected to the 5-d timed AI protocol.     

Proteome profiling of exosomes derived from plasma of heifers with divergent genetic merit for fertility

The current study evaluated exosomes isolated from plasma of heifers bred to have high or low fertility through developing extreme diversity in fertility breeding values, however, key animal traits (e.g., body weight, milk production, and percentage of North American genetics) remained similar between the 2 groups. The exosomes were isolated by a combined ultracentrifugation and size exclusion chromatography approach and characterized by their size distribution (nanoparticle tracking analysis), morphology (transmission electron microscopy), and presence of exosomal markers (immunoblotting). In addition, a targeted mass spectrometry approach was used to confirm the presence of 2 exosomal markers, tumor susceptibility gene 101 and flotillin 1. The number of exosomes from plasma of high fertility heifers was greater compared with low fertility heifers. Interestingly, the exosomal proteomic profile, evaluated using mass spectrometry, identified 89 and 116 proteins in the high and low fertility heifers respectively, of which 4 and 31 were unique, respectively. These include proteins associated with specific biological processes and molecular functions of fertility. Most notably, the tetratricopeptide repeat protein 41-related, glycodelin, and kelch-like protein 8 were identified in plasma exosomes unique to the low fertility heifers. These proteins are suggested to play a role in reproduction; however, the role of these proteins in dairy cow reproduction remains to be elucidated. Their identification underscores the potential for proteins within exosomes to provide information on the fertility status and physiological condition of the cow. This may potentially lead to the development of prognostic tools and interventions to improving dairy cow fertility.     

响应面法优化红曲米中凝乳酶高产菌株的发酵条件

对从红曲米中分离得到的产凝乳酶能力强的菌株M5传代菌株的液态发酵培养基及产酶条件进行优化。首先进行单因素实验得到适宜的氮源为(NH4)2SO4、酪蛋白,无机盐为FeSO4、KH2PO4,适宜的接种量为1%,培养温度为30℃,培养时间为5d,发酵培养基初始pH为6.0。在此基础上通过Plackett-Burman实验筛选出对酶活影响显著的三个因素:(NH4)2SO4含量、培养时间和培养温度。再用Box-Behnken响应曲面实验对三个显著因素进行优化。结果表明,产酶的最佳培养基组分:(NH4)2SO40.53%、FeSO40.05‰、KH2PO40.05%、干酪素0.5%、葡萄糖2%、接种量1%。最佳发酵条件为:培养温度31.3℃、摇床转速为180r/min、培养时间113h、pH6.0。基于响应曲面优化的产凝乳酶培养基组成与发酵条件效果显著,供试菌株M5传代菌株所产凝乳酶活性由45.34SU/mL提高到190.68SU/mL。     

利用影像统计信息选择适用的色域对映模式

色域对映是跨媒体色彩复制的关键处理流程之一,过去的研究显示色域对映算法的表现与原稿内容有密切的关系.前人企图发展一套能够满足不同影像需求的算法.然而对于内容相异的图像而言,这些复杂的算法仍各有长短.因此,提出一套根据影像内容分析,选择最适算法的机制,希望藉由影像最适算法的选择,提升色彩复制系统的整体表现.为了在原稿输入时作实时的影像分析,必须设法降低影像统计的参数数量.为此,提出一套萃取影像关键统计因素的方法.在影像的统计上,撷取愈小的面积,运算成本愈低.研究结果显示,只要在影像的一些重要区域上作关键参数的统计分析,就能够以较低的运算成本,准确预测各影像的最适色域对映算法.     

基于色阶重建的彩色图像增强算法

色阶重建技术已应用于高动态范围图像的处理中.应用色调映射技术和局部亮度适应性原理,提出了彩色图像增强的算法来改善彩色图像的可视性.使用一个参数自适应的可变基的对数函数对亮度图像进行变换,采用双边滤波技术来计算每一像素的局部适应亮度,再对彩色图像的对比度进行调整.实验结果显示,图像的暗区部分获得了较好的可视性和细节,同时对比度获得改善.     

Biology and integrated pest management of Tyrophagus putrescentiae (Schrank) infesting dry cured hams

The biology and physiology of Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae), also known as the ham, cheese or mold mite, is reviewed along with methods that have been evaluated for managing and controlling this pest. This review was conducted because the ham mite is an important target pest of the dry cured ham industry. Methyl bromide has been historically used to control mite infestations, but is now banned or being phased out of use in most countries because it is an ozone-depleting substance. Only commercially available stockpiles and quarantine and pre-shipment methyl bromide are available for use in countries that require such action. This review compares the effectiveness and feasibility of recently investigated methods to control mite infestations on dry cured ham and to discuss integrated pest management plans for ham mites. The review also proposes methods for conducting a prevention and monitoring-based integrated pest management program that relies on definitive mitigation such as fumigation only when mite numbers exceed a critical action threshold.     

Next-generation tools for evolutionary invasion analyses

Evolutionary invasion analysis is a powerful technique for modelling in evolutionary biology. The general approach is to derive an expression for the growth rate of a mutant allele encoding some novel phenotype, and then to use this expression to predict long-term evolutionary outcomes. Mathematically, such ‘invasion fitness’ expressions are most often derived using standard linear stability analyses from dynamical systems theory. Interestingly, there is a mathematically equivalent approach to such stability analyses that is often employed in mathematical epidemiology, and that is based on so-called ‘next-generation’ matrices. Although this next-generation matrix approach has sometimes also been used in evolutionary invasion analyses, it is not yet common in this area despite the fact that it can sometimes greatly simplify calculations. The aim of this article is to bring the approach to a wider evolutionary audience in two ways. First, we review the next-generation matrix approach and provide a novel, and easily intuited, interpretation of how this approach relates to more standard techniques. Second, we illustrate next-generation methods in evolutionary invasion analysis through a series of informative examples. Although focusing primarily on evolutionary invasion analysis, we provide several insights that apply to biological modelling in general.     

具有年龄阶段的离散SCIRS模型在我国流脑中的应用

本文主要研究了具有三个年龄阶段的离散SCIRS模型的动力学性态.首先,利用再生矩阵的方法定义了模型的基本再生数R0,证明了当R01时,模型存在唯一的无病平衡点并且是全局渐近稳定的,当R01时,除了无病平衡点,模型还存在唯一的地方病平衡点.其次,利用法定传染病报告的流脑数据,把模型应用到我国流脑的流行传播中.针对模型中很多参数的不确定性,对基本再生数中的参数进行了敏感性分析.最后,在模型的基础上考虑流脑发病的季节因素对模型加以改进,预测分析了我国流脑的发病情况,数值模拟的结果显示季节因素对疾病进展率的影响程度大于对疾病传染率的影响,为控制流脑在我国的流行传播提供建议.     

二维透明片无狭缝假彩色彩虹全息术

本文提出一种新的二维透明片无狭维彩虹全息技术.这种方法是利用一维光栅和玻璃棒代替实狭缝和通过对参考光编码来实现假彩色彩虹全息,从而可以有效地提高光能利用率,本文对这种新方法进行了理论分析和实验验证.