蓝莓贮藏保鲜技术研究进展

本文介绍了蓝莓的营养成分和保健功效，并综述了国内外贮藏保鲜技术的研究进展，包括冷藏、预温处理、气调、涂膜、熏蒸、UV-C辐射和高压静电场等保鲜方式。鉴于我国蓝莓市场的广阔前景，提出了其产业的发展方向和研究着重点。     

麦棉套种对预留棉行光合有效辐射的影响

对东西行向、预留棉行为１００ｃｍ的三二式麦棉套种方式研究表明，在小麦抽穗后的麦棉共生期间，预留棉行上的平均光合有效辐射仅为一熟棉田的５０％～８０％，株高低和叶片枯黄时光照削弱较小；在麦棉间距相同的情况下，北行棉花接受的ＰＰＦＤ较多，而正午前后南行棉花易受荫蔽，南行棉花适当北移，保持麦棉间距在３０ｃｍ以上，降低小麦群体株高，防止小麦旺长，起垄种棉，都有利于棉花生长发育。     

汉中盆地低山丘陵茶叶生产生态气候分析

通过对汉中盆地现有茶区生态气候状况的分析及与同纬度东部平原茶区比较，找出了汉中茶区生态气候和品质的比较优势与存在问题，提出：在退耕还茶中宜建生态茶园；生态园、老茶园和林区应根据局地小气候条件合理布局交错种植；宜推广无性繁殖和无污染管理技术。     

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.     

Influence of amount and frequency of protein supplementation to ruminants consuming low-quality cool-season forages: efficiency of nitrogen utilization in lambs and performance of gestating beef cows

We evaluated the influence of amount and crude protein (CP) supplementation frequency (SF) on nitrogen (N) use by wethers and the performance of late-gestation beef cows. In exp. 1, seven Western whiteface wethers (31.8 ± 1.4 kg) were used in an incomplete 7 × 4 Latin square to evaluate intake and N use. Wethers received one of the seven treatments in a 2 × 3 factorial design containing two levels of supplemental soybean meal offered at a rate of 100% (F) or 50% (H; 50% of F) of the estimated CP requirement daily, once every 5, or once every 10 d, plus a non-supplemented control (CON). Low-quality cool-season forage (4.9 % CP; dry matter [DM] basis) was provided daily for ad libitum intake. Experimental periods lasted 30 d. In exp. 2, 84 Angus × Hereford cows (560 ± 35 kg) were stratified by age, body condition score (BCS), and expected calving date and allocated to 1 of the 21 feedlot pens (three pens per treatment). Pens were randomly assigned to receive the same treatments as in exp. 1 and cows had free access to low-quality cool-season forage (2.9% CP; DM basis). Cow body weight (BW) and BCS were measured every 14 d until calving and within 24 h after calving. In exp. 1, supplementation did not alter total DM and organic matter (OM) intake (P ≥ 0.26), but both parameters linearly decreased as SF decreased (P = 0.02). Supplementation increased DM, OM, and neutral detergent fiber (NDF) digestibility (P ≤ 0.02). Additionally, F feeding linearly increased DM, OM, and NDF digestibility as SF decreased (P ≤ 0.04). Digestibility of N, N balance, and digested N retained were greater with supplementation (P < 0.01), and N digestibility linearly increased as SF decreased (P = 0.01). Mean plasma urea-N concentration was not only greater (P < 0.01) for supplemented vs. CON wethers but also greater (P = 0.03) for F vs. H. In exp. 2, pre-calving BCS change was greater (P = 0.03) for supplemented cows. A linear effect of SF × supplementation rate for pre-calving BCS change was noted (P = 0.05), as F-supplemented cows lost more BCS compared with H as SF decreased. When considering supplementation intervals greater than 5 d, reducing the quantity of supplement provided, compared with daily supplementation, may be a feasible management strategy to maintain acceptable nutrient use and animal performance while reducing supplement and labor costs.     

褪黑素的添加减轻猪精原干细胞的氧化损伤

旨在研究褪黑素（melatonin,MT）对体外培养猪精原干细胞（spermatogonial stem cells,SSCs）的作用机制。本研究采集3头7日龄健康大白公猪睾丸,利用差速贴壁法获得SSCs。后经形态学观察、碱性磷酸酶染色、标记基因检测及免疫荧光染色鉴定后以SSCs作为试验材料,设置MT浓度梯度（0、50、250、500、1 000 μmol·mL^-1）组处理SSCs,每组设3个重复（n=3）,空白对照组加入0.1% DMSO处理,分别检测添加MT后猪SSCs的细胞活力、活性氧（reactive oxygen species,ROS）水平、谷胱甘肽（glutathione,GSH）含量及凋亡基因表达变化。结果显示：1）分离的克隆团细胞具有SSCs的生长特性,可被碱性磷酸酶染色并表达干细胞标志基因OCT4、SOX2和SSCs标志基因NANOG、PLZF、UCHL1;2）50 μmol·mL^-1以上的MT在处理48 h后可显著提高SSCs的细胞活力（P<0.05）;3） MT可显著降低猪SSCs内ROS水平（P<0.05）,极显著增加细胞内GSH含量（P<0.01）;4） MT可显著抑制猪SSCs内凋亡蛋白Bax和Caspase3的表达（P<0.05）。MT具有清除猪SSCs中的ROS,提高总GSH含量,抑制凋亡基因表达进而提高细胞活力的作用,可为养殖过程中提高公猪繁殖性能提供参考。     

性控奶山羊精液X和Y精子分离比例检测方法的建立

旨在建立可以定量计算奶山羊精液中X、Y精子数量的双重TaqMan荧光定量PCR方法,用以检测经过分离的奶山羊精液X和Y精子的数量和比例,为性控技术的开发和生产应用提供技术支撑。本研究选择X、Y染色体中特异基因F9及ZFY片段设计引物,建立标准曲线,优化荧光定量PCR反应体系和条件。通过对阳性标准品梯度稀释以及对60支已知纯度的性控精液进行测定（3次重复）来检验方法的敏感性和可靠性。结果显示,所建立的双重TaqMan荧光定量PCR方法特异性和重复性好,X和Y精子检测灵敏性分别为47和51 copies·μL^-1;利用该方法对商品化的奶山羊性控冷冻精液中X和Y精子的数量和比例进行计算,其结果与销售公司提供的X和Y精子的纯度无显著差异（P>0.05）,表明该方法结果可靠。本研究建立的计算奶山羊X、Y精子数量的双重TaqMan荧光定量PCR方法特异性和重复性好,灵敏度高,结果可靠,为计算奶山羊精液分离后X、Y精子数量及比例提供了快速可靠的方法。     

一种适用于单胎动物多品种选择的基因组关系矩阵

旨在提出一种新型基因组关系矩阵并验证其在多品种联合群体中的模拟应用效果。本研究利用QMsim软件模拟牛的表型数据和基因型数据;利用Gmatrix软件构建常规G阵;利用R语言构建新型G阵,新型G阵在常规G阵的基础上,将多品种联合群体的非哈代-温伯格平衡位点考虑在内;利用DMU软件使用“一步”法模型计算基因组估计育种值（estimated genomic breeding value,GEBV）;比较不同情况下使用两种G阵的GEBV预测准确性。结果表明,在不同遗传力及QTL数下,不对新型G阵使用A₂₂阵加权就能达到常规G阵使用A₂₂阵加权时的GEBV预测准确性。在系谱部分缺失时,新型G阵不加权较常规G阵加权时GEBV预测准确性高。证明,在系谱有部分缺失时,新型G阵对多品种GEBV的预测有一定优势。