The experiment aimed to establish a high-performance liquid chromatography-tandem mass spectrometry method for the determination of three thiazolinone drugs in fmixed feed additive. The sample was extracted with acetonitrile and purified by primary HLB solid-phase extraction column. Agilent SB-C18 (100 mm × 3.0 mm,1.8 μm) gradient elution separation was used,and quantitative analysis was performed using external standard method.The results showed that the three isothiazolinone drugs had a good linear relationship within the concentration range of 0.25～500 ng/mL,with correlation coefficients (r2)>0.99. The recovery rates of three isothiazolinone drugs at different spiking levels ranged from 64.7％ to 88.3％,with a relative standard deviation (RSD) of 2.6％～10.3％. This method was easy to operate,had good accuracy and high sensitivity,and was suitable for the detection of three isothiazolinone drugs in mixed feed additives.
In order to select suitable silage maize varieties for multiple cropping with autumn-sown triticale in the eastern area of Gansu Province,this experiment conducted a 2-year study on the agronomic traits,fresh yield,and hay yield of 12 silage maize varieties,in order to select the best silage maize varieties suitable for multiple cropping with autumn-sown triticale.This provided a theoretical basis for promoting the efficient production technology of"two crops a yea"forage for silage maize after autumn-sown triticale stubble in the region.The results showed that the fresh yields of Heyu 36 and Beinong Silage 208 after autumn sowing of small black wheat stubble were 74.83 t/hm2and 72.58 t/hm2,respectively,and the hay yields were 24.59 t/hm2 and 22.85 t/hm2,respectively.Moreover,both years showed advantages in high and stable yields.Therefore,Heyu 36 and Beinong Silage 208 could be the main recommended varieties for the production of high-quality forage through multiple cropping of autumn-sown triticale in the the eastern area of Gansu Province.
随黑水虻培育日龄变化其蛋白质、油脂含量也显著改变,5龄幼虫是最佳收获时期,并且培养基类型对黑水虻幼虫蛋白质、油脂含量有直接性的影响.黑水虻幼虫可以以鲜活或冷冻幼虫、黑水虻虫粉、黑水虻脱脂虫粉、黑水虻酶解浆、黑水虻油脂等产品形式添加至水产饲料中.不同的黑水虻饲料产品在不同种类的水产饲料中有不同的适宜添加量.水产饲料中添加适宜量的黑水虻产品,有促进水产动物生产性能、提高水产动物健康状态的效果,而过量添加或黑水虻产品中油脂氧化后对水产动物生产性能和健康状态表现为负面效果.因此,黑水虻作为一类新型的蛋白质和油脂原料,应该了解其培养基类型和产品开发工艺,这是黑水虻饲料产品质量的基础;针对不同的养殖对象应该选择不同的黑水虻饲料产品和适宜的添加量,以获得最佳的效果.而对于黑水虻培育和饲料产品开发,也应该充分利用黑水虻幼虫资源特性开发出不同的饲料产品,以满足水产饲料工业的需求.
本文对修订的GB/T 13087-2020《饲料中异硫氰酸酯的测定方法》进行解读.本次修订增加了方法检出限和定量限、异硫氰酸酯混合标准溶液的配制和应用,更改了方法的适用范围、白芥子酶的制备和用量、气相色谱条件和测定结果计算公式,删除了银量法.经实验验证,修订后标准的方法检出限为2mg/kg,定量限为5 mg/kg;在0～2.0 mg/mL内,丙烯基异硫氰酸酯、丁烯基异硫氰酸酯和戊烯基异硫氰酸酯峰面积与内标物峰面积比值均与质量浓度比值呈良好线性关系,相关系数均大于0.9999;精密度实验RSD为1.53％～9.96％;方法回收率为83.6％～106.9％、RSD为0.30％～8.67％,修订后的国家标准适用于配合饲料、浓缩饲料、精料补充料和饲料原料中异硫氰酸酯的测定.
为研究饲料中添加固定化微生物内源酶(MEE)对采食不同能量水平饲粮肉仔鸡生长性能、屠宰性能、血清生化指标和肠道微生物的影响,选用360只1日龄雄性Cobb-500肉仔鸡,随机分为5组:分别为正常代谢能的基础饲粮组(PC组),在基础饲粮中添加750 mg/kgMEE组(PCE组),较基础降低100 kcal/kg的低能饲粮组(NC组),低能饲粮中添加750、1000 mg/kg MEE组(NCE组、NCH组),试验期42 d.结果表明:(1)低能饲粮中添加MEE可使肉仔鸡生长期的体重、平均日增重和饲料效率达到与正常代谢能组相当的水平,饲粮中添加MEE可显著改善饲料效率(P＜0.05).(2)低能饲粮添加MEE可显著降低肉仔鸡21 d血清尿酸含量,显著提高42 d总蛋白含量(P＜0.05).(3)MEE对肉仔鸡的屠宰率、胸肌率、腿肌率和腹脂率均无显著差异(P＞0.05).(4)基础饲粮添加MEE使肉鸡肠道多尔氏菌、罗斯氏菌等益生菌相对丰度增加,链球菌等有害菌的相对丰度显著降低,低能饲粮中添加MEE会使乳酸杆菌等益生菌相对丰度增加,假单胞菌、肠球菌等有害菌的丰度则相对降低.(5)通过多变量线性回归模型对肠道微生物和血液生化进行分析,结果表明,多尔氏菌与血液中尿酸、肌酐和总蛋白含量呈显著正相关,罗斯氏菌属与血液中肌酐的含量呈显著正相关.不同能量水平饲粮添加MEE均可提高肉仔鸡生长性能,低能饲粮导致的生长受阻在添加MEE后可恢复至正常代谢能组水平;饲粮添加MEE可改善肉仔鸡肠道微生物组成,可能有利于营养物质吸收和提高能量利用率,从而改善饲料效率.
