亚急性瘤胃酸中毒耐受性不同的奶牛血浆和乳中脂肪酸及代谢物组成分析

The present study aimed to explore the differences in plasma and milk metabolism of dairy cows with different subacute rumen acidosis (SARA) tolerance. Twelve fistulated Holstein dairy cows in mid lactation[days in milk=(114±22) d] were selected and fed the same diet consisting of 60% forage and 40% concentrate mixture. On days 20 and 21 of the trial period, the rumen pH was monitored at 0, 2, 4, 6, 8, and 12 h after morning feeding. Milk samples were collected before feeding in the morning and evening. Blood samples were collected from the jugular vein 6 h after morning feeding. All the milk and blood samples were stored in liquid nitrogen for subsequent fatty acid composition and metabolome analysis. Cows with the lowest and highest ruminal pH were assigned into the susceptible (SUS, n=4) and tolerant (TOL, n=4) groups, respectively. The fatty acid composition results showed that the proportions of ≤C16 fatty acids in the blood and milk were significantly increased in the SUS group (P< 0.05), while the proportions of > C16 fatty acids were significantly decreased (P< 0.05). The levels of the saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) in the milk were significantly decreased in the SUS group (P< 0.05). The LC-MS metabolomics results revealed that the L-phenylpyruvate was significantly reduced, while the levels of remaining MG (18: 0/0: 0/0: 0), 9-HODE, niacinamide, isovalerylcarnitine, phosphocreatine, L-glutamic acid, and 12(13) Ep-9-KODE were substantially increased in the SUS group. The results of milk metabolome analysis indicated that the levels of 1-stearoylphosphoglycerolserine and sphingosine were significantly increased, while the levels of 14 different metabolites were significantly decreased in the SUS group (P< 0.05), including glyceryl-phosphoryl-ethanolamine, glycerol 3-phosphate, and orotic acid. These differential metabolites were mainly involved in glycerophospholipid metabolism (P< 0.05), glycerolipid metabolism, and pantothenate and CoA biosynthesis. In conclusion, the fatty acids and metabolic profiles in the plasma and milk of cows with different tolerance to SARA were different. For the SUS group, the amino acid metabolism and the de novo synthesis ability of milk fat was enhanced in the plasma, while the ability to absorb long chain fatty acids from blood was weakened. At the same time, the levels of phospholipid, orotic acid and other nutrients were decreased in the milk, which indicated that the quality of milk was reduced for the SUS cows. © 2021, Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

日粮添加脂肪对牛奶产量及品质的影响

本文综述了日粮添加脂肪对奶牛产奶量、乳蛋白率和乳脂率的影响。     

亚急性瘤胃酸中毒对泌乳奶牛血浆生化指标及代谢组的影响研究

本试验旨在探究亚急性瘤胃酸中毒（subacute rumen acidosis, SARA）对泌乳奶牛血液生化指标和血浆代谢组的影响。试验选用8头装有永久性瘤胃瘘管的泌乳中期奶牛,随机分成对照组（CON）（n=4）和处理组（SARA）（n=4）,CON组与SARA组分别饲喂精粗比为4∶6和6∶4的全混合日粮,试验周期为3周。于试验期每周最后一天晨饲后0、2、4、6、8和12 h进行瘤胃pH的测定,同时在pH测定当天晨饲后6 h采集颈静脉血样,用于血液生化指标和代谢组的分析。结果表明,与CON组相比,SARA组的瘤胃pH显著降低（P=0.002）,两组干物质采食量没有显著差异（P=0.524）。血浆生化指标结果显示,与CON组比较,SARA组奶牛的β-羟丁酸浓度显著降低（P=0.007）,甘油三酯浓度显著升高（P=0.014）。采用液相-质谱（LC-MS）联用技术对血浆进行代谢组学分析,主成分分析（PCA）和偏最小二乘法分析（PLS-DA）结果显示,SARA组奶牛血浆代谢物组成较CON组发生明显变化,两组间共检测到26种差异代谢物（VIP>1 & FDR<0.05）,与CON组相比,SARA组奶牛血浆中的7-酮脱氧胆酸、脱氧胆酸、胆酸、12-酮脱氧胆酸、12（13）Ep-9-KODE、12,13-DHOME和L-天冬酰胺代谢物含量显著升高（FDR<0.05）,而十一烷二酸、十六烷二酸、9-HODE、血氧烷B3、PGE2、L-精氨酸、L-色氨酸、L-苏氨酸、异丁酰甘氨酸、异戊酰甘氨酸、马尿酸、4-羟基马尿酸和6-磷酸-2-脱氢-D-葡萄糖酸酯等代谢物含量显著降低（FDR<0.05）。综上,与CON组比较,SARA组奶牛的脂代谢、氨基酸代谢和糖代谢发生显著变化,这些物质可作为SARA潜在的生物标志物。     

Effect of dietary fish oil on milk yield, fatty acids content and serum metabolic profile in dairy cows

The aim of the study was to evaluate the effects of dietary unprotected fish oil on milk yield, fatty acids content and serum metabolic profile in dairy cows. Forty lactating Polish Holstein-Friesian cows were assigned to two groups. The cows were fed a control basal diet (C group), or a basal diet containing 2% addition of fish oil on mineral carrier (FOM group) during a 8-week period. Supplementing FOM diet of dairy cows had no significant effect on milk fat, milk protein, milk lactose concentration and somatic cells count, but increased the milk yield (36.5 kg/d), (p < 0.05) compared with the control cows (34.28 kg/d). We observed an increase (p < 0.05) in body condition scoring between C and FOM groups. Additionally, higher levels of non-esterified fatty acids and β-hydroxybutyrate acid were noticed in FOM group after 8 weeks of the experiment; however, these serum parameters still were in the reference range. Concentration of insulin was higher (30.40 μU/ml; p < 0.01) in the FOM group compared with the control group (14.03 μU/ml). In the FOM group, significant increase (p < 0.01) in long-chain fatty acids, mainly cis-9, trans-11 CLA and n-3 fatty acids (eicosapentaenoic and docosahexaenoic acids) was observed. The obtained results demonstrated that addition of fish oil to cows' diet could profitably modify the fatty acids in cow's milk.     

Effect of linseed oil supplementation on performance and milk fatty acid composition in dairy cows

Thirty‐six Holstein‐Friesian crossbred lactating dairy cows were used to determine the effects of linseed oil supplementation on performance and milk fatty acid (FA) profile. Three treatments were as follows: basal diet (56:44 Roughage:concentrate [R:C] ratio, dry matter basis) supplemented with 500 g of palm oil as control (PO), 500 g mixture (1:1, w/w) of palm oil and linseed oil (POLSO) and 500 g of linseed oil (LSO). The LSO supplementation had no effects on total dry matter intake (DMI), milk yield and milk composition. Compared to control cows, cows supplemented with LSO increased milk concentrations of cis‐9,trans‐11 conjugated linoleic acid (CLA) and n‐3 FA (P < 0.05), particularly C18:3n‐3, C20:5n‐3 and C22:6n‐3. Feeding LSO reduced concentrations of milk short‐ and medium‐chain saturated fatty acids (P < 0.05) while it increased concentration of milk unsaturated fatty acids (P < 0.05). Milk proportions of n‐3 FA increased, whereas n‐6/n‐3 ratio decreased in the LSO as compared with the control (P < 0.05). In conclusion, supplementing dairy cows' diet based on corn silage with LSO at 500 g/day could improve the nutritional value of milk with potential health‐beneficial FA without detrimental effect on milk composition or cow's performance.     

Impact of fat and selected profiles of fatty acids contained in the colostrum and milk of sows of native breeds on piglet rearing

The aim of this study was to evaluate the effect of the level of fat and selected fatty acids found in the milk of sows on the rearing of native breed piglets. Simultaneously, in order to improve the accuracy of the performed analyses, atomic absorption spectrometry was employed in the applied analytic methodology. The experimental animal material comprised 60 sows of the indigenous White Z?otnicka breed. Colostrum and milk were collected on the first and 14th days of lactation. In all, 240 samples were collected. The following parameters were determined in the course of the experiment: number and weight of piglets, body weight gains as well as deaths of piglets. A total of 1270 born piglets was subjected to investigations. The performed experiments demonstrated that, with the progress of the lactation period, the content of fat and saturated fatty acids (SFA) turned out to be statistically significant and showed a growing tendency. Fat increased by about 2% and palmitic acid (C16:0) increased most, that is by 5%. Linolic (C18:2) and linolenic (C18:3) acids revealed decreasing trends. Irrespective of the day of lactation, the level of unsaturated fatty acids (UFA) determined in sows' colostrum and milk was higher in comparison with that of SFA, and the UFA to SFA ratio ranged from 1.84% to 1.33%. Proportions of n‐6 to n‐3 fatty acids were determined at the level of about 1.6:1.0 in the colostrum and 1.3:10 in milk. The highest daily body weight gains were recorded in the case of piglets derived from sows with the highest fat level – 294 g, while in the case of stearic acid (C18:0), the smaller its concentration in the colostrum and milk of the experimental sows, the better body weight gains of piglets – 262 g. At the same time, stearic acid (C18:0) was found to exert a statistically significant effect on piglet mortality at the level of P ≤ 0.05. Its highest concentration caused the highest proportion of deaths among piglets ‐ 16.23%. The performed analysis of correlations that occurred between fat, fatty acids and traits associated with piglet rearing confirmed that linolic acid (C18:2; n‐6) was highly significantly correlated with piglets' body weights (r = 0.456**) and was negatively correlated with piglets' deaths (r = ?0.312). On the other hand, fat revealed correlation with body weight gains of piglets (r = 0.333*_ and a negative correlation with deaths of piglets (r = ?0344*). Recapitulating, the results of the performed experiments revealed that differences in the levels of fat and fatty acids found in sows' colostrum and milk influenced results of piglet rearing. Together with the increase in the content of fat and UFA in sows' colostrum and milk, piglets were characterized by the best body weight, growth rate, as well as by small mortality.     

Diet-induced milk fat depression: Association with changes in milk fatty acid composition and fluidity of milk fat

This experiment was designed to examine changes in milk fatty acids during fish oil-induced milk fat depression (MFD) and to test the theory that these changes are related to milk fat fluidity. The experiment was divided into three periods: 1) Baseline: all cows (n = 12) received a high fiber diet without fish oil (FO) for 12 days; 2) Treatment: 4 cows/group received the following treatments for 21 days: a) Low fiber diet without FO (LF), b) High fiber diet + FO (HF + FO) and c) Low fiber diet + FO (LF + FO); 3) Post-treatment: cows returned to the baseline diet and were monitored for 12 days. FO was included at 1.6% DM and HF and LF diets had 40 and 26% NDF, respectively. Milk fat content and yield were unchanged by the LF diet, but were reduced by FO diets at both dietary fiber levels and recovered in the post-treatment period. FO diets caused a pronounced reduction in stearic and oleic acid concentrations in milk fat and an equally pronounced increase in trans-18:1 fatty acid concentrations. Milk fat mean melting point (MMP) was correlated with MFD (r = 0.73) and with milk oleic acid concentration (r = − 0.92). The ratio of oleic:stearic in milk fat increased gradually and consistently in response to FO. Trans-C18:1 isomers with double bounds at carbon ≤ 10 increased with greater MFD and those with double bonds at carbon ≥ 11 decreased with greater MFD. Trans-9 cis-11 CLA explained more than 80% of MFD and was strongly correlated with trans-10 C18:1. Maintenance of MMP below 39–40 °C suggests that the mammary gland was able to secrete only milk fat with adequate fluidity and that MFD could be an adaptation mechanism to prevent secretion of milk with higher MMP.     

Challenges in enriching milk fat with polyunsaturated fatty acids

Milk fatty acid composition is determined by several factors including diet. The milk fatty acid profile of dairy cows is low in polyunsaturated fatty acids, especially those of the n-3 series. Efforts to change and influence fatty acid profile with longer chain polyunsaturated fatty acids have proven challenging. Several barriers prevent easy transfer of dietary polyunsaturated fatty acids to milk fat including rumen biohydrogenation and fatty acid esterification. The potential for cellular uptake and differences in fatty acid incorporation into milk fat might also have an effect, though this has received less research effort. Given physiological impediments to enriching milk fat with polyunsaturated fatty acids, manipulating the genome of the cow might provide a greater increase than diet alone, but this too may be challenged by the physiology of the cow.     

Influence of pasture on fatty acid profile of goat milk

The effect of pasture on the fatty acid profile of milk was evaluated using 30 pluriparous goats, which were divided into two homogeneous groups (H and P) of 15 goats each after kidding. Group H (control) goats were housed in a stall and received alfalfa hay, while group P was led to pasture. The goats of both the groups received the same concentrate. Average milk yield did not differ statistically between the groups. The goats of the P group had significantly higher fat content in milk than those of group H (53.7 vs. 61.5 g/day, p < 0.01), while lactose content was significantly higher for group H (66.2 and 61.4 g/day, for groups H and P, respectively, p < 0.05). Among milk fatty acids, pasture significantly affected the percentages of C18:1 cis9, C18:1 trans11, octadecadienoic acid, mono-unsaturated fatty acid and polyunsaturated fatty acid. Pasture highly influenced the c9 t11 conjugated linoleic acid (CLA) (0.778 and 0.513 g/100 g of fat, for group P and H, respectively, p < 0.01), t10 c12 CLA (0.046 vs. 0.029 g/100 g of fat: p < 0.01, for group P and H, respectively, p < 0.01) and SigmaCLA (0.84 vs. 0.56 g/100 g of fat for group P and H, respectively, p < 0.01) concentrations of milk.     

营养水平对荣昌猪肌内脂肪、脂肪酸含量的影响研究

试验选用84头10 kg左右荣昌阉公猪,随机分成2组,每组6个重复,每个重复7头猪,在参照中国瘦肉型猪饲养标准(高营养水平组)、荣昌猪(GB 7223—1987)饲养标准(低营养水平组)配制的2种日粮饲喂条件下,研究日粮营养水平对生长肥育期荣昌阉公猪肌内脂肪、脂肪酸含量及组成的影响。结果表明:本试验条件下,营养水平对生长育肥阶段荣昌猪肌内脂肪含量无显著影响;高营养水平组显著提高荣昌猪35 kg时硬脂酸含量(P0.05)和20 kg时亚麻酸含量(P0.05);荣昌猪的饱和脂肪酸、不饱和脂肪酸和必需脂肪酸含量,高低营养水平组在各个体重阶段差异均不显著(P0.05)。     

亚急性瘤胃酸中毒耐受性不同的奶牛瘤胃上皮形态及功能差异研究

本试验旨在探究SARA（亚急性瘤胃酸中毒）耐受性不同奶牛的瘤胃上皮形态及其功能差异。选取12头装有永久性瘤胃瘘管的泌乳中期荷斯坦奶牛,饲喂精粗比为4∶6的日粮,并根据瘤胃pH值的高低,分为SARA易感组（SUS,n=4）和SARA耐受组（TOL,n=4）。瘤胃上皮形态及功能分析结果显示,与TOL组比较,SUS组奶牛瘤胃上皮的棘突层和基底层厚度明显增厚（P<0.05）,SUS组奶牛瘤胃上皮组织中参与挥发性脂肪酸（VFA）吸收的PAT1、MCT4和DRA基因表达量较TOL组显著下调（P<0.05）,而H+转运载体NHE1、NHE2、NHE3和调节胞内pH的vH+ATPase和Na+/K+ATPase的表达量显著升高（P<0.05）;对参与调控瘤胃VFA代谢的基因定量结果表明,SUS组PDHA1和SREBP2的表达量显著高于TOL组（P<0.05）,而HMGCL-2的表达量显著降低（P<0.05）;此外,SUS组CDK2、CDK6和Cyclin D1、Bad及Caspase-9等参与瘤胃上皮细胞增殖与凋亡的基因表达量显著高于TOL组（P<0.05）。结果说...     

添加酸马奶源乳酸杆菌对犊牛肠道菌群和短链脂肪酸含量的影响

选取刚出生的健康荷斯坦犊牛20头,随机分为酸马奶组、正常组、腹泻组和抗生素组,每组5头。除正常组外,其他3组在相同哺乳的基础上均口服100 mL致病性E.coli O1菌悬液(2.5×10¹¹ CFU/mL)建立腹泻模型,抗生素组添加环丙沙星0.5 mg/kg,试验期15 d。结果表明：酸马奶组犊牛肠道微生物丰富度与多样性显著高于其他3组(P<0.05)。酸马奶源乳酸杆菌干预后显著提高了肠道内厚壁菌门、普雷沃氏菌科、毛螺菌科未确定菌属和拟普雷沃菌属的相对丰度,降低了拟杆菌门、变形菌门、梭杆菌门、放线菌门的相对丰度;酸马奶组犊牛粪便中乙酸、丙酸和丁酸含量显著高于其他3组(P<0.05)。由此可见,犊牛日粮中添加酸马奶源乳酸杆菌可显著提高肠道微生物多样性,增加肠道中有益菌的丰度,降低有害菌的丰度,并显著提高其粪便中乙酸、丙酸和丁酸的含量。     

Indicators of induced subacute ruminal acidosis (SARA) in Danish Holstein cows

Background

The prevalence of subacute ruminal acidosis (SARA) in dairy cows is high with large impact on economy and welfare. Its current field diagnosis is based on point ruminal pH measurements by oral probe or rumenocentesis. These techniques are invasive and inaccurate, and better markers for the diagnosis of SARA are needed. The goal of this study was to evaluate clinical signs of SARA and to investigate the use of blood, faecal and urinary parameters as indicators of SARA. Six lactating, rumen cannulated, Danish Holstein cows were used in a cross-over study with three periods. The first and second periods included two cows on control diet and two cows on nutritional SARA challenge. The third period only included two cows on SARA challenge. Control diet was a conventional total mixed ration [45.5% dry matter (DM), 17.8% crude protein, 43.8% neutral detergent fibre, and 22.5% acid detergent fibre (DM basis)]. SARA challenge was conducted by substituting control diet with grain pellets (50% wheat/barley) over 3 days to reach 40% grain in the diet. Ruminal pH was measured continuously. Blood samples were collected once daily at 7 h after feeding. Samples of faeces and urine were collected at feeding, and at 7 and 12 h after feeding. Blood samples were analysed for pCO2, pO2, pH, electrolytes, lactate, glucose, packed cell volume (PCV), and total plasma protein concentration. Milk composition, ruminal VFA, and pH of faeces and urine were measured.

Results

SARA was associated with decreased (P < 0.05) minimum ruminal, faecal and urinary pH. Daily times and areas of ruminal pH below 5.8, and 5.6 were increased to levels representative for SARA. Significant differences were detected in milk composition and ruminal VFAs. Blood calcium concentration was decreased (P < 0.05), and pCO₂ tended to be increased (P = 0.10). Significant differences were not detected in other parameters.

Conclusions

SARA challenge was associated with changes in faecal and urinary pH, blood calcium concentration and pCO₂. These may be helpful as indicators of SARA. However changes were small, and diurnal variations were present. None of these parameters are able to stand alone as indicators of SARA.     

Influence of dietary fat source on sow and litter performance,colostrum and milk fatty acid profile in late gestation and lactation

The objective of this study was to investigate the effects of dietary supplementation with various fat sources (3.8–3.9% of diet) during late pregnancy and lactation on the reproductive performance, fatty acids profile in colostrum, milk and serum of sow progeny. A total of 80 multiparous sows were randomly fed a control (adding no oil), palm oil (PO), fish oil (FO) or soybean oil (SO) supplemented diet from 90 days of pregnancy to weaning. Supplementation of FO increased litter size of weak piglets, compared with the control‐fed sows (P < 0.05). Dietary FO and SO supplementation, enhanced the weaning survival rate, litter weaning weight, litter weight gain and fat content in milk (P < 0.05). The highest immunoglobulin (Ig)G and IgM levels in colostrum and milk were observed in the FO group (P < 0.05). Meanwhile, the highest concentration of C22:5 (n‐3) and C22:6 (n‐3) in colostrum, milk and piglet serum was observed in the FO group (P < 0.05). Taken together, dietary inclusion of FO or SO improved growth performance of nursing piglets by increasing milk fat output, and FO consumption by sows might benefit the piglets via increasing n‐3 polyunsaturated fatty acid availability and immunoglobulins (IgG and IgM) secretion.     

Effects of increasing amount of dietary Prosopis laevigata pods on performance,meat quality and fatty acid profile in growing lambs

A study with finishing lambs assessed the effect of dietary inclusion of Prosopis laevigata pods (PLPs) on performance, carcass characteristics, meat traits and fatty acid profile of subcutaneous fat. Twenty‐one Rambouillet lambs (27.0 ± 3.0 kg BW) were assigned to one of three experimental diets with 0, 150 and 300 g PLP/kg DM. Evaluation of growth performance lasted 49 days. The experimental design was completely randomized and analysed with a mixed model. Lambs fed diets with 0, 150 and 300 g PLP had similar growth performance. Lambs fed diets with 300 g PLP/kg DM had better (p < 0.05) carcass yield and classification, less (p < 0.05) fat deposition and lower lightness (L*) value (p < 0.05) in meat than lambs fed diets with 0 and 150 g PLP/kg DM. Saturated fatty acids (palmitic and stearic) decreased (p < 0.05) and unsaturated fatty acids (oleic and linoleic) increased (p < 0.05) in subcutaneous fat of lambs fed diets with 150 and 300 g pods as compared with lambs not fed PLP. Prosopis laevigata pods are a safe feedstuff that can replace a third of conventional ingredients and reduce feed costs in growing lambs. Addition of PLP reduced (p < 0.05) total feed cost by 21%.     

益生菌对奶牛亚急性瘤胃酸中毒的保护作用

亚急性瘤胃酸中毒对奶牛的生产性能有很大影响,使用益生菌来稳定奶牛分娩后-产奶过渡期瘤胃pH可以减轻这种代谢紊乱的症状。因此,本试验选择了体重(741±55)kg,产奶期在(212±19.5)d的奶牛4头,试验采用4×4拉丁方设计,共4种日粮:对照组饲喂基础日粮,处理1组为日粮添加0.5 g/d米曲菌,处理2组为日粮添加2.5 g/d米曲菌,处理3组为日粮添加2 g/d粪肠球菌和酿酒酵母菌的混合物。每组经过3 w的适应期、4 d酸中毒期以及3 d恢复期。结果显示:瘤胃最大pH范围在5.6～6.0,占比最高,与适应期和中毒期的结果相似。中毒期间,其他pH范围表现为显著差异(P <0.05)。中毒期,处理3组较对照组显著提高了瘤胃pH(P <0.05),同时处理3组瘤胃pH在5.6～6.0的占比也显著高于对照组(P <0.05)。日粮添加2.5 g/d米曲菌显著降低了产奶量(P <0.05)。奶牛遭受瘤胃酸中毒后,随着时间的推移,丙酸、丁酸和戊酸含量显著升高(P <0.05),而乙酸、异丁酸和异戊酸含量显著降低(P <0.05)。除了处理3组外,其他组瘤胃乳酸含量随时间的增加而升高(P <0.05)。饲喂12 d后,处理3组较对照组显著提高了乳酸含量(P <0.05)。瘤胃白球菌和大肠杆菌含量在饲喂2 h后显著升高(P <0.05),之后在6 h达到稳定。结论 :粪肠球菌和酿酒酵母菌复合物可以缓解奶牛亚急性瘤胃酸中毒的症状,米曲菌可以调控瘤胃pH,但高剂量米曲菌添加水平对瘤胃pH无显著影响。     

改善牛乳脂中共轭亚油酸含量的研究

自从发现共轭亚油酸特殊的生理作用以来,共轭亚油酸就一直是动物营养、药物及食品等研究领域的一个热点,目前对于含有共轭亚油酸的功能性食品的研究越来越受到关注和重视。文中阐述了现阶段改善牛乳脂中共轭亚油酸含量的各种方法和手段,为以后共轭亚油酸的深入研究提供一些参考。     

Quality and fatty acid profile of the milk of indigenous goats subjected to different local diets in Tunisian arid lands

The study tested the hypothesis that certain pastoral forages and olive by‐products, available in arid areas, may positively influence fatty acid composition and physicochemical properties of goat's milk. Thirty indigenous goats (body weight = 25.2 kg; age = 4.1 years) were allocated to three groups. During 60 days, the goats received ad libitum either dried olive leaves + Stipa tenacissima (group OL), khortane grass hay (group Ko) or oat hay (control diet, group OH). Milk samples were collected and analysed for total solids, fat, protein, lactose and ash content and fatty acid profile. Average milk yield did not statistically differ among groups. Milk total solids from OL group were higher in comparison with Ko and C groups (15.3, 14.7 and 14.5%, respectively; p < 0.05). Fat content was also higher for the OL group as compared to the other groups (5.44 vs. 5.01 and 4.66%, respectively, for Ko and OH). No significant differences were observed for the milk content of lactose, protein and ash. The percentage of saturated fatty acids of total milk fat was higher in OL and Ko groups compared to the C group (p < 0.001); the milk whereof was characterized by the highest percentage of monounsaturated (p < 0.01) and total unsaturated fatty acids. Milk fat of Ko and C groups showed significantly higher proportions of rumenic (CLA cis‐9 trans‐11) and vaccenic acids (C18:1 trans‐11) compared to OL milk. The feeding system based on Stipa tenacissima and dried olive leaves resulted in the milk lowest proportion of trans‐fatty acids and the highest proportion of polyunsaturated ω3‐fatty acids (p < 0.05).     

Potential protective effects of thiamine supplementation on the ruminal epithelium damage during subacute ruminal acidosis

In ruminants, the ruminal epithelium not only has the function of absorbing nutrients but also is an important tissue to prevent harmful substances in the rumen from entering the blood circulation. Thus, the normal function of ruminal epithelium is critical for ruminants. However, subacute ruminal acidosis induced by high-concentrate diets often damages the barrier function of ruminal epithelium in ruminants. Recently, many studies have shown that dietary supplementation with thiamine is an effective method to alleviate subacute ruminal acidosis. In order to provide theoretical reference for the in-depth study of subacute ruminal acidosis and the application of thiamine in the future, this review introduces the effects of subacute ruminal acidosis on morphological structure, inflammatory response, and tight junction of ruminal epithelium. In addition, this paper summarizes the role of thiamine in maintaining ruminal epithelial function of ruminants during subacute ruminal acidosis challenge.     

维生素E和脂肪来源对番鸭胸肌脂肪酸组成及脂质稳定性的影响

本试验旨在研究不同油脂(大豆油和鱼油)来源日粮添加不同水平的维生素E对番鸭生长和屠宰性能以及胸肌脂肪酸组成的影响。选择120只1日龄的雌性番鸭随机分为4个处理组,试验基础日粮维生素E水平为20 mg/kg,其中两个处理组分别添加20 g/kg的鱼油和大豆油,另外两个处理组在油脂日粮的基础上分别添加200 mg/kg维生素E,试验分为两个阶段,1~42 d和43~66 d,测定试验期间番鸭的体重、日增重和料比以及屠宰性能和胸肌脂肪酸组成。结果显示:日粮各处理对番鸭生长和屠宰性能均无显著影响(P> 0.05),同时对胸肌成分及屠宰24 h后pH值无显著影响(P> 0.05)。肌肉储存1和7 d后,高水平维生素E均显著降低了丙二醛含量(P <0.05)。鱼油组较大豆油组显著提高了胸肌二十碳五烯酸和二十二碳六烯酸比例(P <0.05),同时n-6脂肪酸比例显著降低(P <0.05),n-3脂肪酸比例显著升高(P <0.05),导致n-6/n-3显著降低(P <0.05)。结论:本试验条件下,番鸭与其他家禽品种一样,饲粮中脂肪酸成分的变化对其肌肉脂肪酸组成有显著的影响。此外,日粮添加的维生素E水平超过生理需要水平时可以延长肉的货架期。