A review of the effect of energy intake on pregnancy rate and litter size-discussed in relation to group-housed non-lactating sows

The number of group-housed non-lactating sows is increasing rapidly in Europe as a consequence of changed legislation initiated by elevated public concern of animal welfare. Lower litter size and pregnancy rate in group compared to individually housed non-lactating sows have been observed in several on-farm experiments. The overall aim of this paper is to consider whether the variation in energy intake in a group of non-lactating sows can influence variation in litter size and pregnancy rate. A review of existing literature with main emphasis on publications after 1980 was carried out to clarify whether pregnancy rate and litter size may be influenced by energy intake. The studies reviewed indicate that low energy intake compared to high energy intake before mating may impair litter size in gilts and in sows that experienced severe weight loss during lactation. Furthermore, moderate energy intake compared to low energy intake in the first 3 days after mating may reduce litter size in the gilt but not in the sows. Both pregnancy rate and litter size might be influenced by very low energy intake in the first 4 weeks of pregnancy. Based upon studies indicating that low ranking sows may consume considerably less than high ranking sows (e.g., 50-80%) in group-housed systems, it is suggested that the variation in feed intake in a group of restricted fed pregnant female pigs may be large enough to influence pregnancy rate and litter size.     

Relation between reproduction performance and indicators of feed intake, fear and social stress in commercial herds with group-housed non-lactating sows

Group-housing of non-lactating sows is becoming increasingly widespread in commercial sow herds in European countries as a result of changed legislation. Group-housing may lead to individual variation in feed intake, stress and fear, which may impair the reproduction performance. However, whether the individual variation in feed intake and the level of stress and fear under commercial conditions is severe enough to impair the reproduction performance is not known. In a detailed farm study including 14 herds with different layouts the relations between various indicators of feed intake, stress and fear and reproduction performance were studied based on 553 focal sows. Twelve percent of all mated sows were re-mated and average litter size was 14.8 born piglets per litter. Chance of pregnancy (P < 0.05) and litter size (P = 0.08) correlated positive with back fat gain from weaning to 3 weeks after mating. Sows eating in less than 20% of all observations at feeding had significant higher risk of returning to oestrus compared to sows eating more frequently. Number of skin lesions correlated positively (P = 0.07) with interval from weaning to first mating. No relations between reproduction performance and lying behaviour, aggressions after mixing or the outcome of three fear tests were found. The results indicate that the unintended individual variation in feed intake in sows group-housed in commercial herds may be large enough to affect the reproduction performance. This calls for management initiatives to reduce unequal feed intake in group-housed sows.     

Genetic determination of individual birth weight, litter weight and litter size in Mukota pigs

Genetic parameters for individual birth weight (IBWT), total number of pigs born (NBT), number of pigs born alive (NBA), number of pigs born dead (NBD) and litter weight at birth (LBWT) were estimated using 1961 Mukota pigs kept at the University of Zimbabwe Farm, Harare, Zimbabwe. Variance components were estimated for IBWT based on a direct-maternal genetic effects model. The genetic relationships among NBT, NBA, NBD and LBWT were assessed using a multi-trait direct effects model. For LBWT, the direct, maternal and common environmental litter proportions on the phenotypic variance were 0.090, 0.033 and 0.009, respectively. After adjustment of IBWT for NBA, phenotypic fractions were 0.091, 0.034 and 0.011 for direct, maternal and litter effects. The correlation between the direct and maternal genetic effects of IBWT was − 0.354 and − 0.295, with and without adjustment for NBT. Heritabilities for NBT, NBA, NBD and LBWT were 0.020, 0.030, 0.088 and 0.196, respectively. Differences in the maternal heritability and the heritability for LBWT, a trait of the dam, are different due to accumulation of observations per litter. Maternal genetic effects are, therefore, of less importance than in highly selected European breeds.     

Seed consumption by millipedes

Seed predation is a key mortality factor for plants that reproduce by seeds. We investigated seed consumption by Cylindroiulus caeruleocinctus (Wood, 1864), an abundant representative of an unrecognised group of seed predators - the millipedes (Diplopoda: Julidae). The consumption of small seed species by millipedes was measured in the absence (41 species) and in the presence (11 species) of alternative food sources (dead leaves). We examined whether millipedes would consume seeds at all and if so whether there were any seed size constraints that determined millipede seed acceptance (i.e., the proportion of millipedes that ate seeds) and seed consumption (i.e., the mass of the seeds eaten). Our results indicated that C. caeruleocinctus readily accepted seeds with 75% of seed species accepted in a no-choice experiment and 100% of seed species in a choice experiment. Seed acceptance decreased with increasing seed mass but increased with increasing millipede mass. Seed consumption increased with the size of the offered seed species but was found to be independent of millipede mass. After the millipedes were given dead leaves to consume, the acceptance slightly decreased, and the consumption of the more preferred seed species decreased. Seeds form a small part of the millipede diet but are consumed regularly. Because of millipedes’ foraging preferences and their patchy distribution they may notably contribute to the local mortality of some seed species in their natural environment.     

抗性家蚕血液中与BmNPV抗性相关铜化合物的分离方法研究

[目的]探究家蚕血淋巴中与BmNPV抗性相关铜化合物的分离方法。[方法]选取对BmNPV具有抗性的家蚕品种和非抗性品种为研究对象,对它们进行添食BmNPV病毒处理。提取家蚕的血淋巴,运用SEC-ICP-MS对2组样品中Cu化合物进行分离和检测。[结果]筛选出优化的体积排阻色谱分离条件:Yarra TM SEC-2000分离柱,30 mmol/L Tris-醋酸为流动相(pH 7.4),流速0.5 mL/min。建立了分离与检测家蚕血液中Cu化合物的SEC-ICP-MS联用技术。BmNPV抗性和非抗性家蚕血液中Cu化合物主要的差异是位于7.6 min的组分。[结论]制备了葡聚糖G100凝胶柱分离并收集可能与BmNPV抗性相关的家蚕血液分离液,为家蚕金属蛋白的分离提供更简便有效的方法。     

天童常绿阔叶林砍伐后凋落物层跳虫群落生态学研究

[目的]了解不同砍伐处理对常绿阔叶林凋落物层跳虫群落结构的影响以及各处理样地跳虫群落恢复状况。[方法]于2009年12月至2010年9月在浙江天童地区常绿阔叶林5个砍伐7年后的恢复样地进行四季采样,对浙江森林公园不同砍伐处理下常绿阔叶林土壤动物优势类群跳虫群落进行调查。样地处理分别为:(Ⅰ)去除大树保留萌枝、(Ⅱ)去除地表植物保留枯枝落叶层、(Ⅲ)去除地表植物和10 cm表土、(Ⅳ)清除下木层保留大树、(Ⅴ)对照。[结果]各处理样地各科跳虫类群组成相差不大,密度从大到小依次为Ⅱ号样地(28.79%)、Ⅳ号样地(21.03%)、Ⅰ号样地(20.75%)、Ⅴ号样地(17.09%)、Ⅲ号样地(12.33%),表现为适度地干扰处理能够让跳虫保持较高密度。不同季节跳虫群落组成不同,且跳虫密度在不同样地季节变化存在差异,总体上夏秋季明显高于春冬季。不同砍伐程度下,各样地凋落物有机碳、总氮和总磷均存在显著差异,随着砍伐程度的加剧,凋落物有机碳和总氮含量逐渐降低。结合不同砍伐程度处理中跳虫群落密度,虽然各处理样地经过了7年的恢复,但不同处理间跳虫群落差异仍较为明显。[结论]跳虫群落对环境变化非常敏感,可作为评价土壤环境受干扰程度的指示种。     

Effect of Various Litter Amendments on Ammonia Volatilization and Nitrogen Content of Poultry Litter

Ammonia volatilization from poultry manure contributes to atmospheric N pollution, negatively affects poultry performance, and decreases the fertilizer value of manure. The objective of this study was to evaluate the effects of alum [Al₂(SO₄)₃·14H₂ O], liquid alum, high acid alum (A7), aluminum chloride (AlCl₃·6H₂ O), fly ash, Poultry Litter Treatment (PLT), and Poultry Guard (PG) litter amendments on NH₃ volatilization and N contents in litter. Two laboratory studies were conducted for 42 d each. The treatments in experiment 1, which were mixed in the upper 1 cm of litter, were 4 g of alum, 8 g of alum, 8.66 g of liquid alum, 17.3 g of liquid alum, 11.2 g of A7, 22.4 g of A7, 4 g of PG, 4 g of PLT, 4 g of fly ash, and 4 g of AlCl₃/100 g of litter. The treatments for experiment 2 were identical to experiment 1, except the fly ash treatment was dropped and an additional 4 g of alum/100 g of litter treatment was added, which was incorporated totally within the litter. The various rates of dry alum, liquid alum, and A7 significantly decreased NH₃ volatilization compared with the controls, with reductions ranging from 77 to 96% for experiment 1 and from 78 to 96% for experiment 2, respectively. Poultry Litter Treatment decreased NH₃ volatilization by 76 and 87% for experiment 1 and 2, respectively. Aluminum chloride decreased NH₃ volatilization by 48 and 92% for experiment 1 and 2, respectively. Litter treated with alum, liquid alum, A7, PLT, and AlCl₃ had a lower pH and a greater N content than the controls in experiment 1 and 2. In contrast, PG and fly ash resulted in a greater pH and were ineffective in decreasing NH₃ volatilization and increasing N contents in experiment 1. However, in experiment 2, PG was effective in reducting NH₃ loss. In this study, the decreased NH₃ volatilization was chiefly associated with reduction in litter pH.     

饲料粉碎机环流分布的试验研究

设计了一套直接测取粉碎机环流运动状态环流分布数据的装置。用数理统计的方法分析所测数据，初步揭示了粉碎机环流运动状态，粒度分布，密度分布，并提出了提高粉碎机效率的几条重要途径。     

新疆玛纳斯河湖积平原中砂物质的特征与环境意义

在野外调查的基础上,利用粒度分析和扫描电镜分析方法研究了新疆玛纳斯河下游湖积平原兴农农场剖面中砂的特征。结果表明,其粒度组成特点与现代沙丘相似。石英砂表面特征为磨圆较差,有蝶形坑和水下磨光面,说明玛纳斯河湖积平原沉积环境在气候干燥时曾出现过为风力堆积。     

Comparison of size vs. life-state classification in demographic models for the terrestrial orchid Cleistes bifaria

Recent studies using capture-recapture modelling in terrestrial orchids have shown relationships among survival, life-state, climate and dormancy, but to date, there has been no rigorous study of the effects of size on demographic rates. Here we use multistate capture-recapture models to investigate the relationships between survival, ramet size, life-state, and propensity for extended dormancy of Cleistes bifaria in two populations in Florida and West Virginia. Using estimated leaf area as a measure of ramet size, we investigated relative fit to the data of models in which ramets were classified by life-state alone (dormant, vegetative, and flowering), size alone (dormant, small, and large), or by a combination of size and state (dormant, small vegetative, large vegetative, small flowering, and large flowering ramets). This scheme allowed us to compare the effects of a size versus state classification on survival and transition probabilities, including the propensity for dormancy. For survival rates, the size-classified model was preferable in terms of parsimony (AIC) to models classified either by state or by a combination of size and state. In C. bifaria, annual survival rate for large ramets was close to 1.0 and for small and dormant ramets, 0.91 and 0.76, respectively. This highlights the importance of protecting large plants. In contrast, a model combining life-state with ramet size was most parsimonious for explaining variation in transition rates. As the ‘size + state’ classification is convenient, holds more information, and seems more closely tied to fitness than classification by either size or life-state alone, it may be particularly useful in planning and assessing conservation management of orchids.