Effects of carcass weight,sex and breed composition on meat cuts and carcass trait in finishing pigs

Pork cutting is a very important processing in promoting economic appreciation across the swine business chain. The goal of this research is to determine the proportion and weight of meat cuts, as well as to analyze the effects of carcass weight, sex and breed composition on meat cuts. Simultaneously, we investigate the correlation between meat cuts, carcass traits and meat quality traits. To assess 17 meat cut traits, 12 carcass traits and 6 meat quality traits, we sample 2 012 pigs from four breeds, including Landrace (LD), Yorkshire (YK), Landrace Yorkshire (LY), and Duroc Landrace Yorkshire (DLY). The results showed that carcass weight, sex and breed composition have significant effects on the weight and proportion of most meat cuts. The proportion of cuts for muscle and bone decrease as carcass weight grows, whereas the proportion of cuts for fat increases. Moreover, the thickness of four-point backfat was significantly increasing (P<0.001) with increase of carcass weights, indicating that large amount of intaking energy in the late finishing stage was used for fat deposition. Besides, the proportion of Shoulder cut (SC) and Back fat (BF) in barrows was significantly higher (P<0.001) than that in sows, whereas the Leg cut (LC) showed the opposite trend. The Loin (LO) proportion and Loin muscle area (LMA) of barrows were significantly lower (P<0.001), but the proportion of fat areas in the image (PFAI) and visual marbling score (VMS) were significantly higher (P<0.001) than those of sows, respectively. In terms of breeds, LD had the longest straight carcass length, significantly longer (P<0.001) than the other three breeds, which partially explains why LD had the largest proportion of the Middle cut (MC). Moreover, the proportion of SC in DLY was the highest. Last but not least, the correlations between the proportions of most meat cuts, and also between meat cuts and meat quality or carcass traits were low or not significant (P>0.05). The effects of carcass weight, sex and breed composition on the meat cuts, meat quality and carcass traits are breed and growth stage dependent. It also reflects the asynchrony of the growth curve between different sexes. Our results laid an important foundation for breeding pig carcass cuts and composition.     

不同品种茶花在干旱胁迫下叶 片气孔和蜡质的差异化表现

摘要：以茶花品种?十八学士''和?情人节''为研究对象，在塑料大棚室温15～25℃下，采用盆栽控水法进行干旱胁迫，利用扫描电子显微镜观测叶片的表皮结构。研究不同品种在干旱胁迫下，叶片表皮结构的差异对抗旱性的影响，为茶花的栽植管护推广和造景应用提供基础性的理论依据。 结果表明，茶花叶片仅有下表皮具有气孔，上、下表皮都有不同程度量的蜡质附着物。随干旱胁迫程度的加重，气孔开合及蜡质积累出现差异性变化。抗旱性较差的品种，主要通过利用蜡质的合成、堆积来堵塞气孔，降低蒸腾作用。抗旱性较强的品种，气孔的保卫细胞在干旱早期就启动闭合响应机制，叶片上表面的蜡质堆积程度更强，能更好的保护叶片免受光照和有害物质的伤害，说明叶片表皮结构对于茶花抗旱性强弱的决定作用较大。     

减氮配施中微量元素肥对冬瓜产量和品质的影响

以铁柱冬瓜为试验材料，采用随机区组田间小区试验，设置CK(不施氮肥)、T1(习惯施肥)、T2(习惯施肥基础上减氮30%)、T3(减氮30%+配施硼钼肥)、T4(减氮30%+配施钙镁肥)和T5(减氮30%+配施钙镁硼钼肥)6种处理，在广东佛山市三水区连续开展两年田间试验，旨在探究减氮配施中微量元素肥对冬瓜产量及品质的影响。结果表明，与T1相比，T2的冬瓜产量下降了8.76%，但未达到显著水平；与T2相比，T4和T5处理显著增加冬瓜产量，分别提高了21.3%和32.2%，且T5处理下的冬瓜产量超过了T1；品质结果显示，T5处理提高了50.0%的VC含量，且与T1相比降低了34.2%亚硝酸盐含量；减施30%氮肥基础上配施钙镁肥的土壤pH显著提高，配施硼钼肥的土壤B含量得到显著提高，配施中微量肥处理的冬瓜植株中Ca和Mo含量较T2均有所提高。综上所述，在华南热带地区冬瓜种植过程中，减氮配施中微肥可保证冬瓜品质和产量，其中中微量肥配施处理的效果最好。上述结果为广东地区露地蔬菜化肥氮的科学减施提供了科学依据。     

有机物料长期施用对稻田土壤养分的影响

通过2010—2021年连续12年的长期定位试验，研究了紫云英、水稻秸秆、商品有机肥等有机物料还田施用对稻田土壤养分的影响。结果表明：施用有机物料可以有效提高稻田土壤氮磷钾和有机质等含量。与单施化肥处理相比，紫云英还田土壤碱解氮含量增加6.97%，商品有机肥配施土壤有效磷含量增加49.30%，水稻秸秆还田土壤速效钾含量增加49.32%。3种有机物料处理土壤有机质增加相近(6.0%～7.5%)，可以改善土壤酸性但差异不显著。不同有机物料对土壤基础养分的增加差异显著，紫云英还田土壤固氮能力最强，商品有机肥配施土壤磷素增加最明显，秸秆还田土壤钾素提高最显著。可见，有机物料长期还田施用是一种培肥土壤的有效措施，有助于稻田土壤的可持续利用。     

玉米ZmFAR1基因的克隆与表达分析

FARs为脂酰辅酶A还原酶，在植物生长发育和抵御非生物胁迫过程中起着重要作用。为进一步研究FARs在玉米中行使的生物学功能，在玉米中克隆1个脂酰辅酶A还原酶1基因(ZmFAR1)，该基因全长1 883 bp，开放阅读框长1 491 bp，编码496个氨基酸，分子量为55.983 k Da。生物信息学分析表明，ZmFAR1蛋白的分子式为C₂₅₂₂H₄₀₁₀N₆₉₀O₇₀₁S₂₄，为稳定的碱性亲水蛋白，存在59个磷酸化位点，未发现信号肽，存在跨膜结构域，最大可能定位于细胞质。氨基酸残基组成中主要以α螺旋和无规则卷曲为主。系统进化树分析表明，ZmFAR1蛋白与南荻和高粱的FAR蛋白相似度最高。利用实时荧光定量PCR技术对ZmFAR1在模拟盐、干旱两种非生物胁迫条件下对根、茎、叶3种组织的表达模式进行研究，结果表明，ZmFAR1呈现组织特异性表达，在叶中的表达量最高。盐和干旱处理下，ZmFAR1的表达量出现明显变化，推测ZmFAR1可能在不同程度参与了玉米对非生物胁迫的应答。     

基于SLAF-seq技术分析甜、糯玉米种质遗传多样性

利用简化基因组测序技术SLAF-seq,对国内外引进选育的81份鲜食甜、糯玉米自交系进行遗传多样性分析。结果表明,共获得803 058个SLAF标签,其中,多态性SLAF标签373 764个。通过序列分析,获得169 128个有效单核苷酸(SNP)多态标记,利用这些SNP标记分析和构建了81份鲜食甜、糯玉米资源的群体结构和系统发生树,并将其分为2个群。结果表明,简化基因组测序技术SLAF-seq能高效、低廉地开发出大量SNP标记,是作物种质资源群体遗传分析的有效工具。研究结果为甜玉米不同基因的聚合、温-热种质杂交育种、鲜食甜、糯玉米亚种间杂交育种提供依据,有利于鲜食甜、糯玉米自交系的高效利用、品种选育及杂种优势群的建立。     

苹果果皮蜡质组分的GC-MS分析

为进一步给研究苹果果皮蜡质组分同苹果贮藏特性之间的关系提供有效的技术手段,以蜜脆和嘎拉苹果为试材,建立一套适合苹果果皮蜡质的气相色谱-质谱(GC-MS)分离和鉴定方法。通过硅胶和氧化铝柱将氯仿提取物分为非极性、弱极性和极性3个馏分,再进行GC-MS分析,并比较分析品种之间的组分。蜜脆鉴定出20种烷烃,18种脂肪酸,18种酯类和4种烯烃。嘎拉鉴定16种烷烃,21种脂肪酸,19种酯类和5种烯烃。蜜脆和嘎拉烷烃均以C29烷和C27烷为主,脂肪酸以饱和脂肪酸为主,嘎拉和蜜脆的烷烃和脂肪酸分别表现出奇数碳优势和偶数碳优势。不同品种间组分存在差异,嘎拉烷烃组分中缺少nC16、nC17、nC32和nC33烷烃,蜜脆中质量分数最高的脂肪酸为饱和脂肪酸十六烷酸,而嘎拉中质量分数最高的脂肪酸为不饱和脂肪酸亚油酸。酯类组分差异最大,仅有6种共有组分。