Dietary fiber in a low-protein diet during gestation affects nitrogen excretion in primiparous gilts,with possible influences from the gut microbiota

We investigated the effects of dietary fiber (DF) supplementation in normal or low crude protein (CP) diets on reproductive performance and nitrogen (N) utilization in primiparous gilts. In total, 77 Landrace × Yorkshire pregnant gilts were randomly allocated to four dietary treatments in a 2 × 2 factorial design. The groups comprised 1) equal intake of normal CP (12.82% and 0.61% total lysine), 2) low CP (LP) (10.53% and 0.61% total lysine), and 3) with or 4) without DF supplementation (cellulose, inulin, and pectin in a 34:10:1 ratio). A low-protein diet during gestation significantly reduced daily weight gain from days 91 to 110 of pregnancy (−162.5 g/d, P = 0.004). From N balance trials conducted at days 35 to 38, 65 to 68, and 95 to 98 of pregnancy, DF addition increased fecal N excretion at days 65 to 68 (+24.1%) and 95 to 98 (+13.8%) of pregnancy (P < 0.05) but reduced urinary N excretion (P < 0.05), resulting in greater N retention at each gestational stage. DF increased fecal microbial protein levels and excretion during gestation. An LP diet also reduced urinary N excretion at different gestational stages. An in vitro fermentation trial on culture media with nonprotein N urea and ammonium bicarbonate (NH₄HCO₃) as the only N sources revealed that microbiota derived from feces of gestating gilts fed the high DF diet exhibited a greater capacity to convert nonprotein N to microbial protein. Microbial fecal diversity, as measured by 16S rRNA sequencing, revealed significant changes from DF but not CP diets. Gilts fed an LP diet had a higher number of stillbirths (+0.83 per litter, P = 0.046) and a lower piglet birth weight (1.52 vs. 1.37 kg, P = 0.006), regardless of DF levels. Collectively, DF supplementation to gestation diets shifted N excretion from urine to feces in the form of microbial protein, suggesting that the microbiota had a putative role in controlling N utilization from DF. Additionally, a low-protein diet during gestation negatively affected the litter performance of gilts.     

Methyl donors dietary supplementation to gestating sows diet improves the growth rate of offspring and is associating with changes in expression and DNA methylation of insulin‐like growth factor‐1 gene

The study aimed to investigate the effects of maternal dietary methyl donors on the performance of sows and their offspring, and the associated hepatic insulin‐like growth factor‐1 (IGF‐1) expression of the offspring. A total of 24 multiparous sows were randomly fed the control (CON) or the CON diet supplemented with methyl donors (MD) at 3 g/kg betaine, 15 mg/kg folic acid, 400 mg/kg choline and 150 μg/kg VB₁₂, from mating until delivery. After farrowing, sows were fed a common lactation diet through a 28‐days lactation period and six litters per treatment were selected to be fed until at approximately 110 kg BW. Maternal MD supplementation resulted in greater birthweight (p < 0.05) and increased the piglet weights (p < 0.01) and litter weights (p < 0.05) at the age of day 28, compared with that in CON group. The offspring pigs in the MD group had greater ADG (p < 0.05) and tended to lower F:G ratio (p = 0.07) compared with that of CON group from day 28 to 180 of age. The offspring pigs from MD group had greater serum IGF‐1 concentrations and expressions of hepatic IGF‐1 gene and muscular IGF‐1 receptor (IGF‐1r) protein at birth (p < 0.05), and greater hepatic IGF‐1 protein (p = 0.03) and muscular IGF‐1r gene expressions (p < 0.05) at slaughter, than that from the CON group. Moreover, the methylation at the promoter of IGF‐1 gene in the liver of newborn piglets and finishing pigs was greater in the MD group than that of the CON group (p < 0.05). In conclusion, maternal MD supplementation throughout gestation could enhance the birthweight and postnatal growth rate of offspring, associated with an increased expression of the IGF‐1 gene and IGF‐1r, as well as the altered DNA methylation of IGF‐1 gene promotor.     

油葵含油率及脂肪酸组成与土壤盐含量的关系研究

通过盆栽试验研究不同土壤含盐量对油葵含油率及脂肪酸组成的影响，结果表明：子实含油率和籽仁含油率受土壤盐含量的影响下降明显，且籽仁含油率受到的影响大于子实含油率。土壤含盐量的增加，促进棕榈酸、亚油酸的生成，抑制油酸的生成，但硬脂酸、亚麻酸的变化受土壤盐含量的影响不明显。土壤盐含量对籽仁含油率组分的影响棕榈酸>油酸>亚油酸>硬脂酸>亚麻酸。     

广州园林亭廊与植物配置初探

通过对广州的余荫山房、云台花园、黄花岗公园、广州兰圃、流花湖公园等庭园的亭廊与植物配置关系的调查,总结出亭、廊的植物配置方法。     

荔枝体细胞胚胎发生早期的3种内源激素含量变化

采用高效液相色谱法（HPLC）测定了荔枝下番枝品种体细胞胚胎发生早期的内源激素含量的变化.结果表明：内源生长素IAA含量先降低,达到一个最低值,此时是荔枝体胚发生早期原胚Ⅰ阶段,随后就会逐渐上升,直到球形胚阶段时,达到一个最高值;从胚性愈伤组织到胚性愈伤组织II阶段,其内源脱落酸（ABA）含量总的变化趋势先升高,紧接着下降到一个低谷,此时是紧密结构阶段,随后在发育到球形胚阶段的过程中又逐渐升高;内源细胞分裂素（CTK）含量变化趋势呈“M”形.ABA与IAA和ABA与CTK的质量比增大,将有利于荔枝体细胞球形胚的形成.     

RRR-RRR Ⅱ级杆组的等效系统动力学建模

将等效的思想与有限元的方法结合起来,用等效元素法建立了RRR Ⅱ级杆组的动力学等效模型,给出了其动力学微分方程,将建模的关键归结为二阶张量Tia和三阶张量Tibc的建立以及等效质量阵的组装。对给定的RRR—RRR六杆机构进行了建模和求解,给出了其动力响应曲线。实例表明,此方法与传统方法比较,无论从微分方程的列写,还是由计算机进行的解算,都显示出强大优势,解题效率高。     

Effect of dietary protein and temperature on the growth and health of juvenile New Zealand black‐footed abalone (Haliotis iris)

The protein requirements for optimal growth and health of juvenile New Zealand black‐footed abalone (Haliotis iris) under different water temperatures were investigated. Six diets with different crude protein amounts (0, 10, 20, 30, 40 and 45%) and two temperature regimes (13–21 and 8–16 °C) were used to culture juvenile abalone over a 4‐month period. Growth (shell lengths and animal weights) and health (survival, activity and mucous production) parameters were recorded for animals within all protein and temperature combinations. Proximate analyses and amino acid profiles were also performed on the diets, soft bodies (including gonad), and shells to evaluate the overall nutrient contents (diet and animal) and requirements (animal). The results indicate that the protein requirements for juvenile H. iris are higher when the environmental temperatures are low. Thus, increasing the dietary protein level results in better growth [i.e. increase in soft body (including gonad) crude protein and mean protein gain] and health (i.e. more goblet cells and thicker epithelial layers). Results from amino acid profiles in abalone soft bodies (including gonad) and shells show that these parameters did not change considerably with different dietary protein levels, but temperature did affect the concentration of several amino acids in both soft bodies (including gonad) and shells.     

猪圆环病毒Ⅱ型ORF2基因的克隆与表达

猪圆环病毒II型(PCV2)是引起断奶后仔猪多系统衰竭综合症(PMWS)的重要病原。本研究用PCR方法扩增PCV2截短的ORF2基因并亚克隆至表达载体pGEX-6P-1,构建的重组表达质粒命名为pGEX-ORF2,将重组质粒转化大肠杆菌BL21 (DE3),在37℃经IPTG诱导4小时。PCV2的cap蛋白以包涵体形式得到有效表达。经SDS-PAGE及Western blot分析表明表达的重组蛋白分子量约为46KD,重组蛋白具有良好的免疫学活性。     

猪流行性腹泻病毒RT-PCR检测方法建立及初步应用研究

为建立一种特异、敏感的PEDV的检测方法。根据GenBank中公布的猪流行性腹泻病毒CV777株的M基因序列,设计了一对特异性引物,扩增长度为680 bp的片段。将PCR产物进行测序,与CV777株、SH5株M基因的同源性分别为99.2%和97.6%。试验表明：该方法具有较好的特异性和敏感性,并能检测到PEDV的RNA浓度下限为100 pg/μL。从福建省的3个地区共采集58份哺乳仔猪腹泻样品,并应用此方法进行检测,其阳性检出率为87.9%。     

黄土高原庆阳地区春玉米生育期对气候变化的响应

旨在研究黄土高原庆阳地区春玉米的生育期气候变化特征及物候变化规律,给粮食生产安全及情报服务提供理论依据。通过以黄土高原庆阳地区有代表性的物候观测站的春玉米生育期内的气温、降水、≥10℃的活动积温作为研究对象,来分析气候变化背景下春玉米生育期的气候资源及物候变化特征。结果表明:春玉米全生育期内平均气温呈上升趋势,上升速率为0.6℃/10a;平均降水量呈减少趋势,减少速率为8.7 mm/10a,但绝大多年份雨水能满足玉米生长发育需要;积温呈增加态势,变化速率为58.0℃/10a,热量资源充足;稳定通过10℃的日期为偏早出现趋势,变化速率为6.3 d/10a。春玉米全生育期日数呈现为缩短的响应特征,减少量为1.7 d/10a。因此,气候变化对春玉米种植较为有利,尤其热量资源增加,有利于拓展种植界限及提高产量。要充分利用气候资源,因地制宜,选择适合的品种及播期进行生产,同时要加强田间管理,充分挖掘气候增产潜力,提高玉米种植的经济效益,为精准脱贫提供决策依据。