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71.
高精料日粮饲喂诱导泌乳奶牛发生乳脂抑制的机制 总被引:1,自引:0,他引:1
高精料饲喂导致奶牛乳脂率降低的相关机制目前还不清楚.本研究通过探究高精料饲喂对肝脏内乳脂前体代谢的影响,揭示奶牛(Bos taurus)发生乳脂抑制的相关机制,将10头泌乳期(25+5)d荷斯坦奶牛随机分为2组,分别饲喂精粗比4∶6(对照组)和6∶4(实验组)日粮.饲喂20周后实施肝脏血管瘘手术,护理4周,进行如下实验:1)统计奶牛产奶量,每周测定乳成分;2)采集空腹进出肝脏血液,检测甘油三酯(triglyceride,TAG)和游离脂肪酸(free fatty acid,FFA)的含量;3)活体穿刺取肝脏组织,qRT-PCR检测肝脏中脂代谢相关基因的表达.结果表明,高精料饲喂6~l8周可提高产奶量,18周后乳脂率显著降低(P<0.05).高精料组奶牛肝脏TAG和FFA的净输出含量显著(P<0.05)或极显著降低(P<0.01);肝脏中参与脂肪酸合成代谢的固醇调节元件结合蛋白-lc基因(sterol regulating element binding protein-1 c,SREBP-1c)、乙酰辅酶A羧化酶基因(acetyl-coa carboxylase,ACC)和脂肪酸合成酶基因(fatty acid synthetase,FAS)表达显著(P<0.05)或极显著(P<0.01)下调;参与脂肪酸分解代谢的过氧化物酶体增殖物激活受体α基因(peroxisome proliferators-activated receptor α,PPARα)和肉毒碱棕榈酰转移酶-1基因(carnitine palmitoyltransterase-1,CPT-1)表达显著上调(P<0.05).高精料饲喂导致奶牛肝脏脂肪酸合成代谢减弱而分解代谢增强,肝脏内乳脂前体物发生重分配,乳脂前体物输出减少,影响了乳脂合成.本研究揭示了高精料饲喂导致奶牛乳脂率降低的机制,为改善奶牛乳脂率提供了理论基础. 相似文献
72.
73.
脂肪作为一种重要的品质参数,在大西洋鲑鱼片中的分布很不均匀。为寻找一种能替代脂肪化学检测的快速无损的方法,该研究应用可见/近红外高光谱成像测定大西洋鲑鱼片的脂肪含量分布。分别采用可见/短波近红外(400-1100 nm)和近红外(900-1700 nm)系统获取大西洋鲑鱼片样本的高光谱图像。提取样本图像的平均光谱并与其相应的脂肪含量化学值采用偏最小二乘回归(partial least squares regression,PLSR)和最小二乘支持向量机(least-squares support vector machines,LS-SVM)建立相关性模型。为降低高光谱图像的共线性和冗余度,基于竞争性自适应重加权算法(competitive adaptive reweighted sampling,CARS)分别在可见/短波近红外和近红外光谱区间提取16个(468,479,728,734,785,822,863,890,895,899,920,978,1005,1033,1040,1051 nm)和15个(975,995,1023,1047,1095,1124,1167,1210,1273,1316,1354,1368,1575,1632,1661 nm)特征波长,并分别建立PLSR和LS-SVM模型。特征波长模型的性能优于全波段模型,且近红外区间的特征波长PLSR模型为最优,预测决定系数(R2p)为0.92,预测均方根误差(root mean square error of prediction,RMSEP)为0.92%,剩余预测偏差(residual predictive deviation,RPD)为3.50。最后,将最优模型用于预测高光谱图像上所有像素点的脂肪含量以展示样本上脂肪的分布。此外,还基于该技术对大西洋鲑整鱼片实现了脂肪分布可视化。结果表明高光谱成像技术结合化学计量学方法在大西洋鲑鱼片脂肪的定量和分布可视化上有一定的研究和应用前景。 相似文献
74.
Fatty acid composition of neutral lipids (NLs), phospholipids (PLs) and free fatty acids (FFAs) from intramuscular fat (IMF), lipid oxidation and lipase activity in muscle Semimembranosus (SM) and msucle Biceps femoris (BF) of dry-cured Xuanwei ham during the 90-d salting stages were analysed. The salt content increased from 0.34 to 3.52%in BF and from 0.10 to 5.42%in SM during the 90 d salting stage, respectively. PLs of IMF in both BF and SM decreased 54.70%(P〈0.001) and 34.64%(P〈0.05), furthermore, the saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) of PLs in both muscles were hydrolysed almost isochronously. FFAs were increased from 0.46 g 100 g-1 lipids to 2.92 g 100 g-1 lipids in BF at the end of salting, which was lower than SM (from 1.29 g 100 g-1 lipids to 9.70 g 100 g-1 lipids). The activities of acid lipase, neutral lipase and acid phospholipase all remained active in the 90 d. The thiobarbituric acid reactive substances (TBARS) was slowly increased to 1.34 mg kg-1 muscle in BF and to 2.44 mg kg-1 muscle in SM during the salting stage. In conclusion, the controlled salting process prompted the hydrolysis of PLs of IMF notably and increased the lipid oxidation of muscles within some limits. 相似文献
75.
An Abattoir Survey on the Frequency of Fatty Liver Syndrome in Dairy Cows from the Suburbs of Tehran
One hundred and six Holstein and Holstein x native cows were inspected before and after slaughter, and liver samples were taken. The fat content of all the liver samples was estimated by an extraction method (Soxhlet). The livers of 29 cows (27%) were classified as fatty. Seventeen of the animals were newly calved, 47 were non-pregnant, 33 were pregnant and 9 were dry, the median values for the fat content of their livers being 60.6, 34.4, 34.7 and 33.8 mg/g, respectively. The median concentration of liver fat in the first group was significantly different from that in each of the other groups (p < 0.01). 相似文献
76.
Agwunobi LN 《Tropical animal health and production》1999,31(6):383-389
Day-old Lohman broiler chicks (n = 120) were fed on five starting diets for 4 weeks in groups of 24 birds. The starting diets contained 0%, 9%, 18%, 27% and 36% sweet potato tuber as a replacement for maize. From the fifth week, the 120 birds were tested in groups of 30 on four finishing diets containing 0%, 15%, 30% and 45% sweet potato tuber as a replacement for maize. The carcass quality was significantly (p>0.05) improved due to a significant (p>0.05) reduction of abdominal fat in the birds fed on the 45% sweet potato finisher diets. However, the birds on the sweet potato diet continually passed wet dropppings, resulting in a significant (p>0.05) reduction in body weight and feed conversion efficiency. The optimum levels of inclusion of sweet potato in the diets were considered to be 27% and 30% for starting and finishing broiler chickens, respectively. Sweet potato diets may be a remedy for fatty broilers. 相似文献
77.
To study the accuracy and precision of intramuscular fat prediction by ultrasound (USIMF) in lean cattle, prediction models were developed based on 325 pure and crossbred beef and dual purpose bulls originating from I) commercial herds (n = 180) and II) a performance test station (n = 145). The bulls were scanned across the 12th thoracic vertebrae using a Pie 200 SLC scanner. Five images were collected per individual bull for later processing in the lab. After slaughter, a 2.5 cm cross-sectional sample located by the 13th thoracic vertebrae was used for chemical analysis to determine intramuscular fat % (CHIMF; Mean 1.25%, SD 0.6%) at the image site. The data were analysed sequentially involving 1) the Total Dataset, 2) Dataset I and 3) Dataset II. Prediction models were developed separately for each dataset, using stepwise regression procedures. The validation model R2, RMSE, overall mean bias, SEP, rP and rank correlations for CHIMF and USIMF based on the best prediction model (Dataset I) were 0.48, 0.46%, − 0.02%, 0.46%, 0.70 and 0.67, respectively. Further improvement in prediction accuracy can probably be achieved by increasing the size of datasets and the CHIMF variation. The results strongly indicate that ultrasound has potential for IMF prediction in lean cattle, although the value in indirect selection of breeding cattle for meat quality needs to be further evaluated. 相似文献
78.
79.
甲壳素、壳聚糖对家禽生产性能及脂肪代谢的影响 总被引:1,自引:0,他引:1
本文就甲壳素、壳聚糖的发现、来源、制备、结构和性质;甲壳素、壳聚糖对家禽生产性能及脂肪代谢的影响;甲壳素和壳聚糖的降脂机理及今后的研究发展方向进行综述。 相似文献
80.
猪肌肉组织LPL基因表达的发育性变化及其与肌内脂肪沉积关系的研究 总被引:4,自引:1,他引:4
以40-90 kg 6个体重组的莱芜猪和鲁莱黑猪共72头去势公猪为试验对象(每组6头),采用相对定量RT-PCR方法,以-βactin基因为内标,分析肌肉组织LPL基因表达的发育性变化及其与肌内脂肪沉积的关系。结果表明:莱芜猪与鲁莱黑猪肌肉组织中LPL基因表达的发育性变化趋势基本相似,随体重的增长,莱芜猪50-70kg阶段LPLmRNA表达丰度逐渐下降(P<0.05),80 kg阶段迅速回升出现一个峰值后再次下降;鲁莱黑猪LPLmRNA表达丰度随体重的增加呈缓慢下降趋势,70 kg以后变化不大并维持较低水平,其前期(40-60 kg)与后期(70-90 kg)的表达量差异显著(P<0.05)。总体上莱芜猪肌肉组织LPL基因表达量略高于鲁莱黑猪(P>0.05)。相关分析表明,莱芜猪和鲁莱黑猪肌内脂肪相对含量与肌肉组织LPLmRNA表达的发育性变化分别呈显著(P<0.05)和极显著(P<0.01)的正相关。研究结果提示:猪肌肉组织LPL是肌内脂肪沉积的重要参与者,其编码基因的表达具有明显的体重发育特征,并对肌内脂肪的沉积具有一定程度影响。 相似文献