Heritability and genetic correlations between rumination time and production traits in Holstein dairy cows during different lactation phases

So far, rumination has been used as a proxy for monitoring dairy cow health at farm level. However, investigating its genetic aspects as well as its correlation with other important productive traits may turn this management tool into a new informative selection criterion. However, scientific evidences on genetic correlation among rumination time (RT) and milk production and milk composition are still scarce. Therefore, the objective of this study was to estimate the heritability of RT across three lactation phases and its genetic correlation with milk production, milk composition and somatic cell count (SCC). Results of our study showed that heritability for RT was 0.34 and was constant across lactation. The mean genetic correlations between RT and milk production and composition traits were 0.07 (milk production), ?0.07 (protein yield), ?0.31 (fat yield), and ?0.32 (fat/protein ratio). The mean genetic correlation between RT and the SCC was 0.05.     

Bovine foetal sex determination—Different DNA extraction and amplification approaches for efficient livestock production

Foetal sex determination using polymerase chain reaction (PCR) in mammals is based on the amplification of gender‐specific foetal DNA sequences circulating in maternal blood. The bovine synepitheliochorial placenta does not allow a direct contact between the trophoblast and the maternal blood, resulting in difficult passage of foetal DNA and, consequently, its very small amounts in maternal bloodstream. Circulating cell‐free foetal DNA (ccffDNA) encompasses short nucleotide fragments (300–600 bp) in maternal circulation. The aim of this study was to assess this non‐invasive method in accurate prenatal sexing in early and late gestational periods in comparison with ultrasound diagnostics. As various DNA isolation and amplification methods were tested, their success in obtaining reliable results was evaluated. Two groups were tested, each consisting of 20 pregnant cows. Blood of a bull and a non‐pregnant heifer was the controls. Extraction of foetal DNA was accomplished by three different methods: using tubes with silicone membranes, a single‐tube extraction without silicone membranes and phenol–chloroform extraction. Following each extraction method, foetal DNA was amplified using PCR and real‐time PCR with both bAML and TSPY primers in a separate reaction. Positive results were obtained only after amplification of foetal DNA extracted with a single‐tube extraction kit. In comparison with ultrasound examination results and foetal gender recorded at birth, the sensitivity of the PCR test was 90% in Group I, but the technique failed to detect male foetuses in Group II. The real‐time PCR test sensitivity in Group I was 90% and in Group II 91.6%.     

Endocannabinoids as endometrial inflammatory markers in lactating Holstein cows

The objective of this study was to consider endocannabinoid system as inflammatory markers in bovine endometrium to better understand the role of this system in regulating many of the functions that are related to inflammatory condition. At day 26 post‐partum, fourteen cows were divided into two groups depending on the inflammatory condition: 1‐ subclinical endometritis (n = 7, with purulent or mucopurulent uterine discharge detectable in the vagina) and 2‐ healthy (n = 7, No (muco)) purulent discharge. Blood samples were collected at 26 and 30 days relative to calving to determine plasma tumour necrosis factor (TNF) and lipopolysaccharide‐binding protein (LBP) concentrations; moreover, uterine biopsy was carried out on day 26 post‐partum to measure mRNA abundance of TNF, interleukin‐1B (IL1B), interleukin‐6 (IL‐6), C‐X‐C motif chemokine ligand 8 (CXCL8), endocannabinoid receptor (CNR2), N‐acyl phosphatidylethanolamine phospholipase D (NAPEPLD), fatty acid amide hydrolase (FAAH), N‐acylethanolamine acid amidase (NAAA) and monoglyceride lipase (MGLL) by real‐time PCR. Results showed mean plasma concentrations of TNF and LBP were lower in healthy cows compared to subclinical endometritis cows (p < .05). Relative mRNA expression for NAAA and FAAH was decreased (p < .05), and relative mRNA expression for CNR2 and NAPEPLD increased in cows with subclinical endometritis compared to healthy cows. In conclusion, relative mRNA expression of TNF, IL1B and CXCL8 and plasma concentration of LBP increased during inflammatory condition along with decreased endocannabinoids hydrolyzing enzyme (NAAA and FAAH), increased enzymes that synthesize endocannabinoids (NAPEPLD) and relative gene expression of the endocannabinoid receptor; together, these contribute to increased endocannabinoids levels during inflammation. Overall, we provide evidence that endocannabinoid system is altered in endometrium tissue during inflammation through increased mRNA expression of CNR2 and synthesis enzyme and decreased mRNA expression of hydrolyzing enzymes interfere with pro‐cytokine production and signalling, which may interfere with the onset and progression of inflammation.     

彭水县烟叶化学成分协调性不同年份间变异分析

为掌握重庆市彭水县烟叶协调性的时间变异特征,对2005—2014年上(B2F)、中(C3F)、下(X2F)部烟叶的协调性指标进行分析。结果表明:在彭水烟区烟叶钾氯比和两糖差变异系数较大,两糖比年度间变异最小,而其他化学成分含量的变异幅度在30%以内。从不同年份部位间变异来看,各化学成分及协调性指标均有逐渐稳定的趋势。从不同部位间对比来看,上部叶各化学成分协调性指标年度间变异总体上大于中、下部叶。     

一类具有饱和发生率的虫媒传染病模型研究

考虑虫媒传染病具有潜伏期的特征,研究了一类具有饱和发生率的时滞传染病模型的动力学行为,确定了疾病是否流行的阈值R_0.当R_01时,无病平衡点全局渐近稳定,疾病将最终灭绝;当R_01时,唯一地方病平衡点条件稳定,系统会产生Hopf分支.     

定苗时间对峦大杉1年生苗木生长的影响

探究定苗时间对峦大杉苗期生长动态与生长节律影响,优化定苗时间,为育苗提供理论与技术支持。以当年生峦大杉幼苗为试验材料,开展不同定苗时间试验,采用定株观测并应用Logistic方程拟合生长动态的方法,分析定苗时间对苗木生长动态和生长节律的影响效应。研究结果表明,定苗时间影响苗高地径生长效应随处理时间推移而显现,是个动态过程。Logistic方程能够很好地拟合峦大杉苗木生长。定苗时间显著影响苗高、地径线性生长速率、最大线性生长速率和线性生长量,但对苗高地径线性生长始期、终期、线性生长持续期无显著性影响;苗高生长初期定苗较其他处理显著提高苗高和地径的线性生长量线性生长速率、最大线性生长速率,建议增加速生期的养分和水分供给以提高苗木质量。峦大杉合理定苗时间是苗高生长初期（6月30日）。     

Effect of allele combinations at Ppd-1 loci on durum wheat grain filling at contrasting latitudes

Flowering time is the most critical developmental stage in wheat, as it determines environmental conditions during grain filling. Thirty-five spring durum genotypes carrying all known allele variants at Ppd-1 loci were evaluated in fully irrigated field experiments for three years at latitudes of 41°N (Spain), 27°N (northern Mexico) and 19°N (southern Mexico). Relationships between weight of central grains of main spikes (W) and thermal time from flowering to maturity were described by a logistic equation. Differences in flowering time between the allele combination causing the earliest (GS100/Ppd-B1a) and the latest (Ppd-A1b/Ppd-B1a) flowering were 7, 20 and 18 days in Spain, northern Mexico and southern Mexico, respectively. Flowering delay drastically reduced the mean grain filling rate (R) and W at all sites. At autumn-sowing sites, an increase of 1°C in mean temperature during the first half of the grain filling period decreased W by 5.2 mg per grain. At these sites, W was strongly dependent on R. At the spring-sowing site (southern Mexico), W depended on both R and grain filling duration. Our results suggest that incorporating the allele combinations GS100/Ppd-B1a and GS105/Ppd-B1a (alleles conferring photoperiod insensitivity) in newly released varieties can reduce the negative effects of climate change on grain filling at the studied latitudes.     

不同采收期对余甘果实品质和耐贮性的影响

以福建余甘主栽品种‘粉甘’果实为材料，研究不同采收期对余甘果实品质和耐贮性的影响。结果表明：随着采收期的延迟和果实成熟度的提高，余甘果皮颜色由青绿色逐渐变成黄绿色，果核颜色由深绿色变成棕褐色，果实重量和大小逐渐增加，果实可食率和营养品质提高。可用果实重量和大小、果形指数、果实可溶性固形物、可滴定酸、维生素C含量、果实可食率作为确定余甘果实采收成熟度的参数。同时，不同采收期对余甘果实的耐贮性影响不同，盛花期后179 d采收的果实耐贮性最好，在常温25±1℃下贮藏16 d后，好果率为91%，失重率为3.51%。     

Some Agronomic Strategies for Organic Quinoa (Chenopodium quinoa Willd.)

Quinoa is a potential new seed crop for protein feed and human consumption in Europe, with tolerance to a range of abiotic stresses. For this purpose the study was planned to analyse the effect of important agronomic strategies like nitrogen level, N application strategy, row spacing and harvest time on yield and quality of quinoa. The experiments took place in the field of the experimental station of the Faculty of Science, University of Copenhagen. Three levels of organic nitrogen from slurry was used (60, 120 and 180 kg N ha^?1), supplied either all at once at sowing, or split between sowing and beginning of the reproductive phase. The effect of row spacing and harvest time was studied by harvesting seeds at seed maturity, which occurred 2–3 weeks prior to the mechanical harvest by threshing, and a couple of months after. Yield increased significantly (P ≤ 0.05) with an application up to 180 kg N ha^?1, reaching 2200 kg ha^?1. Increasing N also caused a significantly increased seed weight (up to 3.3 mg) and protein content (up to 17 %). N level did not affect number and amount of weeds. Split application with part of the N applied at bud formation did not have a significant effect on yield. Delayed harvest had a negative influence on seed weight, whereas protein content was stable after harvesting even a month after seed maturity. A late harvest significantly reduced seed germination, being reduced by 50 % after a 2‐month delay. A conclusion from this study is that both yield and protein content of seed can be manipulated by N level and application strategy. Harvest time is important for securing a high seed quality measured as seed germination, seed weight and protein content. A fast germination of quinoa is an important characteristic demonstrating that the crop has good possibilities for being well‐established in the field when free from weeds at the time of sowing. The choice of row spacing is important and depends on weed control method. Weed control strategy should be developed based on modern precision tools.