种子产量对鼠类扩散栓皮栎坚果的影响

为了解林木种子产量对鼠类种子扩散行为的影响,于2008 年和2009 年,在国有济源市愚公林场调查了栓皮栎的种子雨;在每年的种子雨结束后,选择次生林生境,研究了鼠类对人工释放栓皮栎坚果的扩散,旨在探讨种子产量与种子扩散间的关系。结果表明:1)取食栓皮栎坚果的鼠类主要有大林姬鼠、社鼠和岩松鼠,2008 年的鼠类捕获率(2% )低于2009 年(10%),其差异并未达到显著性水平;2)栓皮栎的种子雨构成和产量存在年际差异,2008 年以完好种子为主且产量高于2009 年,而2009 年以败育种子为主;3)2008 年人工释放栓皮栎坚果的中位存留时间显著高于2009 年;4)2008 年鼠类对栓皮栎坚果的平均扩散距离显著低于2009 年,且两年的搬运距离几乎都集中在9 m 以内;5)2008 年鼠类对栓皮栎坚果的埋藏比例显著高于2009 年。结果提示,在种子高产年份,可能有较多的种子逃脱动物的取食,从而增加种子萌发和幼苗建成的机会,最终促进植物的更新。     

Development of recombinant antibody-based enzyme-linked immunosorbent assay (ELISA) for the detection of skatole

The occurrence of boar taint and the European Commission recommendation to discontinue the surgical castration of pigs by the year 2018 creates an urgent need for new analytical methods that are simple, affordable, and suitable for field testing. We describe the generation and engineering of a skatole-specific antibody derived from a synthetic antibody library and the development of ELISA for its detection. The immunoassay is capable of detecting skatole with IC50 of 222 μg L⁻¹, which is within the analytical threshold level suggested for skatole, and with low cross-reactivity interference from other indolic compounds.     

Biotin interference in immunoassays based on biotin-strept(avidin) chemistry: An emerging threat

Biotinylated antibodies/antigens are currently used in many immunoassay formats in clinical settings for diversified analytes and biomarkers to offer high detection selectivity and sensitivity. Biotin cannot be synthesized by mammals and must be taken as an essential supplement. Normal intake of biotin from various foods and milk causes no effect on the streptavidin/biotin-based immunoassays. However, overconsumption of biotin (daily doses 100–300 mg) poses a significant problem for immunoassays using the biotin-strept(avidin) pair. Biotin interferences are noted in immunoassays of thyroid markers, drugs, hormones, cancer markers, the biomarker for cardiac function (β–human chorionic gonadotropin), etc. The biotin level required for serious interference in test results varies significantly from test to test and cannot easily be predicted. Immunoassay manufacturers with technologies based on strept(avidin)-biotin binding must investigate the interference from biotin (up to at least 1200 ng/mL or 4.9 μM of biotin) in various formats. There is no concrete solution to circumvent the biotin interference encountered in blood samples, short of biotin removal. Considering the short half-life of biotin in the human body, patients must stop taking biotin supplements for >48 h before the test. However, this scenario is not considered for patients in emergency situations or those with biotinidase deficiency, mitochondrial metabolic disorders or multiple sclerosis. Apparently, a rapid analytical procedure for biotin is urgently needed to quantify for its interference in immunoassays using strep(avidin)-biotin chemistry. To date, there is no quick and reliable procedure for the detection of biotin at below nanomolar levels in blood and biological samples.Traditional lab-based techniques including HPLC/MS-MS cannot process an enormous number of public samples. Biosensors with high detection sensitivity, miniaturization, low cost, and multiplexing have the potential to address this issue.     

Welfare of entire male pigs is improved by socialising piglets and keeping intact groups until slaughter

In today's production systems, pigs raised for slaughter are mixed many times, resulting in stress and fighting. The negative consequences of mixing are probably more severe with entire males than with castrates, as they fight more. In this project, we studied a system without castration where entire male pigs met unfamiliar pigs only once. Piglets from two litters were allowed to visit each other from circa 2 weeks of age through an opening between the farrowing pens. Entire males from these litters were kept in intact groups from weaning and onwards, and they were slaughtered pen-wise in intact groups. Control pigs were raised and weaned in their litters and mixed with unknown pigs when moved to the growing–finishing unit. They were slaughtered by split marketing based on individual weight. In total, 96 entire males from 24 litters were studied. Activity and social interactions of pigs were studied by direct observations on three observation occasions per pen for pigs kept in intact groups and four occasions for control pigs. All pigs were inspected for skin lesions during raising and at slaughter. Results showed that fewer pigs in intact groups were resting (17.1% v. 28.5%; P = 0.044) and they showed less aggressive behaviour (16.1 v. 27.7 number of interactions per hour; P = 0.001) than control pigs when moved to the growing–finishing unit. They also got fewer skin lesions compared with control pigs (15 v. 35; P < 0.001). Consequently, control pigs tended to grow slower during the 1st week after mixing; however, growth rate during the whole growing–finishing phase did not differ between treatments (P = 0.205). Control pigs directed more aggressive behaviour towards non-litter mates than towards litter mates during the whole growing–finishing phase, whereas pigs from the other treatment made no difference between litter mates and other familiar pigs. At 67 kg, there was more sexual behaviour (mounting) among control pigs (7.6 v. 3.4; P = 0.033), but after slaughter no differences were found in testis weight or boar taint compounds. At slaughter, more entire males that were slaughtered pen-wise and kept in intact groups were without skin lesions compared with the mixed control pigs (74% v. 13%; P < 0.001). This study shows that the welfare of entire male pigs can be improved by socialising piglets and by keeping them in intact groups during raising and at slaughter.     

Effects of hydroxy‐delta‐5‐steroid dehydrogenase, 3 beta‐ and steroid delta‐isomerase 1 polymorphisms on fat androstenone level and gene expression in Duroc pigs

A high level of androstenone in porcine adipose tissue is a major factor contributing to boar taint. Porcine hydroxy‐delta‐5‐steroid dehydrogenase, 3 beta‐ and steroid delta‐isomerase 1 (3β‐HSD, also known as HSD3B1) plays a key role in the hepatic metabolism that catalyzes androstenone to β‐androstenol. Therefore, 3β‐HSD is a candidate gene for boar taint. This study aimed to investigate functional 3β‐HSD polymorphisms in Duroc pigs. We found eight single nucleotide polymorphisms (SNPs) in the full‐length porcine 3β‐HSD. Four of the SNPs had restriction enzyme sites, and we genotyped them in 147 uncastrated male Duroc pigs using a polymerase chain reaction–restriction fragment length polymorphism method. Pigs with the GG genotype at the g.165262G>A locus (SNP5) had significantly lower androstenone levels than did those with other genotypes (P = 0.030). SNP5 also was associated with differences in 3β‐HSD mRNA levels: pigs with the GG genotype had higher levels than those with other genotypes (P = 0.019). The SNP5 polymorphism could affect the hepatic catabolism of androstenone and consequently impact androstenone accumulation in the adipose tissue. Therefore, SNP5 in the 3β‐HSD of Duroc pigs could be a useful selective marker for decreasing boar taint.     

Effect of a gonadotropin-releasing factor vaccine on follicle-stimulating hormone and luteinizing hormone concentrations and on the development of testicles and the expression of boar taint in male pigs

The objective of this study was to determine the effect of using a gonadotropin-releasing factor (GnRF) vaccine on follicle-stimulating hormone (FSH) and luteinizing hormone (LH) concentrations in plasma, the size of testicles, and the expression of boar taint in male pigs. Vaccinated pigs were compared with surgically castrated pigs and entire males. Pigs were randomly assigned to three treatment groups: surgically castrated during the first week of life (T01, n = 274), immunized twice during the fattening period with a GnRF vaccine, the first when 13 to 14 wk of age and the second when 20 to 21 wk of age (T02, n = 280), and entire males (T03, n = 56). From a subgroup of both T01 and T02 and from all pigs of group T03, blood samples were collected immediately before second vaccination (T02) and again before slaughter at either 24 to 25 or 26 to 27 wk of life to determine the plasma concentrations of LH and FSH. Testicles were removed after slaughter and their size was determined. Meat and fat samples from all pigs of T02 and T03 as well as 25% of the pigs of T01 were examined with the cold cooking and fat melting test. Immediately before the second vaccination (T02 only), LH and FSH concentrations were not significantly different between T02 and T03. However, LH and FSH concentrations were significantly higher in T01 compared with T02 and T03. Before the first slaughter date, LH and FSH concentrations were significantly lower in T02 than in T03. Testicle size was significantly lower in T02 compared with that in T03. In T02, 98% (235 of 239) of the samples were rated negative for boar taint by the cooking test, whereas in T03, 94% (48 of 51) were rated positive. In the fat melting test, 97% of T02 were rated negative and 3% (7 pigs) were rated positive, including the pigs tested positive in the cold cooking test. In T03, 94% were rated positive. All pigs (7 of 239) in T02 that were positive for boar taint in the cooking or melting test and that were tested had androstenone and skatole concentrations in backfat below threshold levels of 1 μg/g and 0.2 μg/g, respectively.     

A survey of helminth infection in Eurasian badgers (Meles meles) in relation to their foraging behaviour in a Mediterranean environment in southwest Portugal

This study provides the first data on the helminth fauna of the Eurasian badger in the southwestern edge of its range (Grândola Mountain, Portugal) and interprets the results in relation to badger diet and feeding behaviour. By examination of 163 badger faecal samples, faecal developmental stages (eliminative forms) of four helminth species and one genus were identified: one cestode (Atriotaenia incisa) and four nematodes (Mastophorus muris, Molineus patens, Uncinaria criniformis and Strongyloides sp.). The overall prevalence of parasites was 62%, with limited seasonal variation. Single parasite excretions were dominant and Strongyloides sp. excretion was the most common. Diet assessment based on 450 faecal samples revealed that badgers consumed mainly insects and fruits. No correlation was detected between helminth prevalence and diet. Apparently, diet (mainly insects) and feeding behaviour (fossorial), together with the species’ social behaviour (anal scent marking of group members), facilitate the infection with helminths. The helminth fauna of Eurasian badgers in Grândola Mountain has isolationist characteristics, apparently indicating low host colonisation.     

Evaluation of various boar taint detection methods

The aim of this study was to evaluate the performance of various boar taint detection methods, measure the relationship between them and identify possible points of improvement for boar taint detection. The methods used to evaluate boar taint in the carcasses of 448 entire male pigs and 17 barrows were the hot iron method (n = 442), a standardised (n = 323) and home (n = 58) consumer meat-evaluation panel, an expert panel assessment of meat and fat (n = 464) and laboratory analysis of skatole, androstenone and indole in fat (n = 464). The axillary odour of a number of slaughtered entire male pigs was also investigated (n = 231). As correlation coefficients were generally weak, a positive result for one of these detection methods did not per se result in a positive result for all other methods. Results of one detection method could not be generalised. The choice to use one or more detection methods deserves consideration depending on the aim of the study. In this paper, we suggest some possible improvements for evaluating boar taint with a consumer panel based on our results and experience. The home consumer evaluation was correlated with the concentration of indole (r = 0.27) but not with skatole or androstenone. We therefore recommend that lab analyses include indole testing. The hot iron method seems to be an easy and fast detection method, which yields comparable or better correlation coefficients with the other detection methods than an expert panel evaluating fat samples. However, the reliability of the hot iron method depends on the training and reliability of one or two assessors. Efforts should be made to further optimise this method by evaluating the effect of testing conditions. The axillary odour score was moderately correlated with the other detection methods (up to 0.32). More research is needed to evaluate the possibilities of axillary odour as a boar taint detection method.