饲喂不同配比油脂饲料对肉鸡肉品质及肌肉中脂肪酸组成的影响

研究日粮中添加不同配比油脂对肉鸡肉品质、肌肉胆固醇含量及脂肪酸组成的影响。选取648只1日龄AA肉鸡,随机分成6组,CON为对照组(饲喂基础日粮),SO为正对照组(日粮中添加豆油),LO为负对照组(日粮中添加猪油),COP、COC、COV组分别在日粮中添加以棕榈油为主的配比油脂、以椰子油为主的配比油脂、多种植物油组成的配比油脂,实验期为42d。结果表明：COP组胸肌24h的滴水损失显著升高(P＜0.05);COC组腿肌烹饪损失显著降低(P＜0.05)。LO组胸肌不饱和脂肪酸/饱和脂肪酸得到提高(P＜0.05);SO、LO、COP、COC组n-3多不饱和脂肪酸含量均得到提高(P＜0.05);SO、COC组n-6多不饱和脂肪酸含量高于CON组(P＜0.05);除COV组外,各组n-6/n-3低于CON组(P＜0.05)。SO组胸肌胆固醇含量低于除LO组外的各组(P＜0.05)。结论：配比油脂组提高了肉鸡肌肉中多不饱和脂肪酸(PUFA)含量,对肉鸡肉品质没有产生不良的影响,豆油组改善了胸肌中脂肪酸比例并降低胆固醇含量,以椰子油为主的配比油脂次之。     

日粮中添加亚麻籽和双低菜籽混合原料提高鸡蛋中N-3PUFA含量的研究

选取健康25周龄农大三号粉壳蛋鸡180只,按体重一致的原则随机分成5组,每组6个重复,每个重复6只鸡.第1组为对照组,饲喂玉米-豆粕型基础日粮,其他几个处理组分别在基础日粮中添加10%亚麻籽+1%鱼油(2组),10%亚麻籽+5%去皮双低菜籽(3组),5%亚麻籽+10%未去皮双低菜籽(4组),5%亚麻籽+10%去皮双低菜籽(5组),旨在研究每组中的两种不同原料的配比对鸡蛋中n-3PUFA含量和蛋鸡生产性能的影响.饲料和鸡蛋中脂肪酸采用气相色谱分析.试验结果表明:10%亚麻籽+1%鱼油组n-3PUFA含量显著高于对照组和其他处理组(P<0.01),10%亚麻籽+5%去皮双低菜籽n-3PUFA富集量低于鱼油组(P<0.01),但显著高于对照组和其他两组(P<0.01);10%亚麻籽+1%鱼油组鸡蛋中DHA含量明显高于其他几组(P<0.01),其他3个处理组间无显著性差异(P>0.01);各处理组中添加的两种混合n-3PUFA原料对蛋鸡生产性能无显著性影响(P>0.05);感官评分结果表明:10%亚麻籽+1%鱼油可使鸡蛋产生鱼腥味,降低鸡蛋的感官评分.综合考虑蛋中n-3PUFA富集量和人们对鸡蛋的可接受性,本试验认为日粮中添加10%亚麻籽+5%去皮双低菜籽可用于高富集量n-3PUFA鸡蛋的生产.     

摄入有机硒与亚麻籽油对猪肉及其肉制品品质的影响

研究日粮添加有机硒和亚麻籽油对猪背长肌中硒含量、脂肪酸组成、肌原纤维蛋白特性及加工肉制品的影响。选取192头"杜×长×大"三元杂交猪,随机分为4组,设为C组(0.3 mg/kg亚硒酸钠+1.5%大豆油),S1组(0.3 mg/kg酵母硒+1.5%大豆油),S2组(0.5 mg/kg酵母+1.5%大豆油)及SL组(0.3 mg/kg酵母硒+1.5%亚麻籽油)。研究发现有机硒能显著提高猪背长肌中的硒贮存量(P0.05);亚麻籽油能改善肉品的n-6/n-3比例;亚麻籽油相比大豆油能显著提高肌原纤维蛋白的溶解性和凝胶强度(P0.05);0.5mg/kg有机硒在7~12d的储藏期内能减少香肠的脂质氧化(P0.05),但是香肠的微观结构和感官评价不受有机硒和亚麻籽油的影响。因此在日粮中添加亚麻籽油和有机硒有益于富硒富n-3PUFA猪肉的生产和加工。     

亚麻籽和茶多酚对肉鸭生长性能、屠宰性能、血液抗氧化能力和肌肉不饱和脂肪酸含量的影响

研究以亚麻籽为n-3 PUFA来源的肉鸭饲粮中添加茶多酚(TP),对其生长性能、屠宰性能、抗氧化能力和肌肉不饱和脂肪酸含量的影响。选用240只1日龄樱桃谷肉鸭,随机分为4组,其中对照组饲喂基础饲粮,实验组一、二、三分别饲喂含3%亚麻籽、3%亚麻籽+100 mg/kg TP、3%亚麻籽+200 mg/kg TP的实验饲粮。实验期为40d。结果表明:实验组一的平均日采食量(ADFI)和料重比(F/G)显著高于对照组(P 0.05);实验组二、三的ADFI和F/G与对照组差异不显著(P 0. 05)。屠宰率、半净膛率和全净膛率各组间均差异不显著(P 0. 05)。实验组三血浆的总抗氧化能力(T-AOC)、总超氧化物歧化酶(T-SOD)活力显著高于对照组(P 0. 01),丙二醛(MDA)含量显著低于对照组(P 0. 01)。各实验组腿肌中n-3 PUFA的含量均显著高于对照组(P 0. 05)。因此,饲粮中添加3%亚麻籽会显著增加樱桃谷肉鸭的料重比,以及肌肉中n-3PUFA的含量,但对屠宰性能无显著影响。在肉鸭饲粮中添加3%亚麻籽用于生产富含n-3 PUFA肉产品时加入200 mg/kg TP对肉鸭生长性能及机体抗氧化效果最佳。     

饲料及饲养试验烟酸铬对肉鸡生产性能、胴体品质及血液生化指标的影响

选择1日龄艾维茵商品肉鸡360羽,随机分成3组,每组3个重复,每个重复40羽,试验期为6周.研究了在日粮中分别添加0,0.2,0.4 mg/kg铬量的烟酸铬对肉鸡生产性能、胴体品质及血液生化指标的影响.结果表明:在0～6周龄的肉鸡日粮中添加不同水平的烟酸铬对肉鸡生产性能无显著影响(P＞0.05).但添加烟酸铬可明显改善胴体品质,显著提高胸肌率(P＜0.05)、降低腹脂率(P＜0.01),对肝脂率、屠宰率、净膛率却无显著影响(P＞0.05).当添加0.4 mg/kg铬量的烟酸铬时, 却能显著降低血清中葡萄糖(P＜0.05)、总胆固醇(P＜0.05)及甘油三酯的含量(P＜0.01),并显著提高血清中高密度脂蛋白-胆固醇的质量浓度(P＜0.05).     

饲粮中添加不同水平油菜花粉对蛋黄和鸡肉组织脂肪酸组成的影响

目的分析饲粮中添加不同水平油菜花粉对蛋黄和鸡肉组织脂肪酸组成的影响。方法选用210日龄的海兰褐壳蛋鸡540只,随机分为4组,基础饲粮中分别添加0%(A组)、3%(B组)、5%(C组)、8%(D组)的油菜花粉,预饲1周后,连续饲喂50 d后改喂基础饲粮,观察至第70 d。结果实验前期(0~50 d)蛋黄中ω-3PUFA、α-ALA、DHA含量随着饲粮中油菜花粉添加量的增加而增加,D组增加极显著(P0.01)。蛋黄中ω-6/ω-3PUFA比值随着花粉添加量的增加而降低,其中D组在第5d至30d降低极显著(P0.01)。实验后期(50~70d)蛋黄中ω-3 PUFA、α-ALA、DHA含量和ω-6/ω-3PUFA比值逐渐恢复至对照组水平。添加花粉对脑组织中脂肪酸组成无显著影响(P0.05);胸肌中ω-3PUFA含量随着花粉添加量的增加而明显降低,其中C组差异极显著(P0.01),D组差异显著(P0.05);各花粉添加组鸡肝中ω-3PUFA含量分别为1.96%、1.89%、3.11%和3.28%,D组差异极显著(P0.01),脂肪组织中ω-3PUFA含量分别为1.61%、1.84%、1.86%、2.27%,D组差异显著(P0.05)。结论饲粮中添加油菜花粉能够提高蛋黄、肝脏和脂肪组织中ω-3PUFA的含量,在3%、5%和8%三个花粉添加水平中以8%花粉添加水平效果最好。     

沸石对肉鸭肝脏抗氧化性能和组织中金属元素含量的影响

研究沸石对樱桃谷肉鸭肝脏抗氧化性能和组织中金属元素含量的影响.结果表明:添加3％、5％和7％沸石能不同程度地提高肉鸭肝脏SOD活性(P＞0.05),降低MDA含量(P＞0.05),显著降低肉鸭肝脏中的镉含量(P＜0.05),还能一定程度上提高肝脏、胸肌、腿肌中铜、铁、锌的含量;其中1％沸石组能显著提高肝脏中铁和.锌的含量(P＜0.05),5％沸石组能显著提高肝脏铁的含量和胸肌中铁和锌的含量(P＜0.05).     

金针菇菇脚对肉鸡血清生化指标和脂肪沉积的影响

目的：研究金针菇菇脚（Flammulina velutipes stembase,FVS）对Arbor Acres（AA）肉鸡血清生化指标、腹脂沉积、肝脏以及肌肉中脂肪含量的影响。方法：选用1 日龄AA肉鸡270 羽,随机分为5 个处理组（每个处理组3 个重复,每个重复18 只）：空白组（饲喂基础日粮）、抗生素组（基础日粮＋5 mg/kg黄霉素）、3 个水平的FVS组（基础日粮＋2%、4%、6% FVS,均为质量分数,下同）,实验期为42 d。结果：1）与空白组相比,日粮中添加2%和6%的FVS可显著降低肉鸡血清中甘油三酯（triglyceride,TG）含量（P＜0.05）;2）各剂量的FVS均可降低21 日龄肉鸡血清中总胆固醇（total cholesterol,TC）含量（P＜0.05）,显著提高21 日龄肉鸡血清中瘦素（leptin,LEP）含量（P＜0.05）,而对高密度脂蛋白胆固醇（high density lipoprotein cholesterol,HDL-C）和低密度脂蛋白胆固醇（low density lipoprotein cholesterol,LDL-C）水平无显著影响（P＞0.05）;3）与空白组相比,FVS可显著提高肉鸡体质量（P＜0.05）,各剂量的FVS可明显降低胸肌、腿肌、肝脏脂肪含量,而各组肉鸡粪便中脂肪含量无显著差异（P＞0.05）;4）与空白组相比,日粮中添加4%和6%的FVS可显著降低42 日龄肉鸡腹脂率（P＜0.05）,日粮中添加2%和6%的FVS可显著提高42 日龄肉鸡的激素敏感脂肪酶（hormone-sensitive lipase,HSL）活力（P＜0.05）。结论：在肉鸡饲粮中添加FVS能够促进肉鸡生长,同时起到一定的降血脂和减少机体脂肪沉积的作用。     

谷氨酰胺对22-28日龄热应激肉鸡骨骼肌氧化损伤的改善作用

本试验旨在研究谷氨酰胺(Gln)对热应激肉鸡骨骼肌抗氧化能力的影响。选用300只22日龄AA肉鸡,随机分为5个处理组:常温对照组和4个热应激组(基础日粮分别添加0%、0.5%、1%和1.5%Gln),试验期为22～28日龄。结果表明:与对照组相比,热应激组肉鸡胸肌和腿肌丙二醛(MDA)含量显著升高,胸肌抗超氧阴离子能力、总抗氧化能力(T-AOC)、谷胱甘肽(GSH)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和谷胱甘肽巯基转移酶(GST)显著降低,腿肌GSH和SOD显著降低(P0.05)。与热应激组相比,日粮添加1.5%Gln显著降低肉鸡胸肌和腿肌MDA含量,胸肌T-AOC、GSH、CAT和GST显著升高,腿肌GSH和SOD含量显著升高(P0.05)。Gln能缓解热应激肉鸡的肌肉氧化损伤,提高肌肉抗氧化能力。     

大豆异黄酮对樱桃谷鸭生长和屠宰性能的影响

选用健康1日龄樱桃谷SM2商品代雏鸭128只,随机分为4组,公、母各半.对照组饲喂基础日粮,试验I、Ⅱ、Ⅲ组日粮是在基础日粮中分别添加5、10和15 mg/kg的大豆异黄酮,于42日龄屠宰.结果表明:①试验组公鸭、母鸭每周平均体重均显著高于或高于对照组,试验Ⅱ组的平均体重显著高于其他各组(P＜0.05).大豆异黄酮对樱桃谷鸭母鸭和公鸭的生长具有明显的促进作用,而且其作用效果呈现剂量效应,以10 mg/kg添加水平效果最为明显.②试验Ⅱ组母鸭的屠宰率和胸肌率高于其他各组(P＞0.05);母鸭和公鸭的腹脂率均显著低于其他各组(P＜0.05).试验Ⅲ组母鸭的腿肌率显著高于其他各组(P＜0.05).试验组间母鸭的皮脂率差异不显著(P＞0.05);但均显著低于对照组(P＜0.05),试验Ⅲ组母鸭的皮脂率最低.试验Ⅲ组公鸭的屠宰率、胸肌率和腿肌率高于其他各组(P＞0.05),试验I、Ⅲ组公鸭的腹脂率也显著低于对照组(P＜0.05),试验Ⅱ组公鸭的皮脂率显著低于其他各组(P＜0.05).大豆异黄酮发挥了降脂作用,且以10 mg/kg的作用最为明显.     

高脂日粮中n-6、n-3脂肪酸配比对小鼠机体抗氧化能力及血脂的影响

为了了解不同n-6、n-3系多不饱和脂肪酸配比对小鼠机体抗氧化能力和血脂的影响,通过测定饲喂6周不同饲料C57小鼠血浆中总抗氧化能力(T-AOC)、超氧化物岐化酶(SOD)、丙二醛(MDA)、总胆固醇(TC)、甘油三酯(TC)、高密度脂蛋白胆固醇(HDL)、低密度脂蛋白胆固醇(LDL)和致动脉粥样硬化指数(A11并进行统计分析.实验结果表明,从改善血脂、提高机体抗氧化能力来看,n-6、n-3不饱和脂肪酸比例10:1组效果好于5:1组,若添加抗氧化剂LA,有利于改善机体脂质过氧化产生的不良影响,对预防动脉粥样硬化会起到积极的作用.     

有机溶剂中酶促酯化合成n-3 PUFA甘油酯的研究

利用脂肪酶催化游离型的n-3PUFA与甘油发生酯化反应生成甘油酯,研究了多种因素对酯化程度的影响.研究结果表明：利用脂肪酶Novozym435,在6mL的正己烷中,反应温度40℃,甘油用量2g,n-3PUFA0.4g,初始水分含量0.5%,在反应1h后添加1g分子筛,酶添加量25mg,震荡频率150r/min,在此条件下反应24h酯化度可达90%以上.n-3 PUFA甘油酯中以甘油二酯（56.06%）为主,其次是甘油三酯（31.25%）和甘油一酯（12.07%）,游离脂肪酸（0.39%）的含量比较低.n-3 PUFA甘油酯的脂肪酸组成以DHA（73.36%）和EPA（13.49%）为主,单不饱和脂肪酸的含量仅有1.69%,几乎不合饱和脂肪酸.     

N3系多不饱和脂肪酸膳食参考摄入量的研究进展

近年来n-3系多不饱和脂肪酸(N-3 Polyunsaturated Fatty Acids,n-3 PUFAs)在提高婴幼儿认知及视力发育、增强免疫及预防精神疾病、癌症、炎症、心血管疾病(Cardiovascular Disease,CVD)等方面的作用倍受人们的重视,n-3PUFAs的膳食参考摄入量也成为这些研究领域的重要关注焦点之一。为了更好地发挥n-3 PUFAs在促进人体营养、发育、健康以及疾病预防等方面的重要作用,本文综述了世界上许多知名的研究机构及官方组织关于对不同人群的n-3 PUFAs推荐摄入量(Recommended Nutrient Intake,RNI)及适宜摄入量(Adequate Intake,AI),以及它们对n-6/n-3脂肪酸的摄入比例以及n-3 PUFAs的可耐受最高摄入量(Tolerable Upper Intake Level,UL)进行的科学研究、探讨,同时还对n-3 PUFAs在使用过程中的不稳定性及注意事项进行了阐述,可以为我国不同人群的n-3 PUFAs膳食参考摄入量、普通食品中应用添加n-3 PUFAs以及n-3 PUFAs摄入补充方面提供更加充分、完整的科学依据和参考。     

Use of milk fatty acids composition to discriminate area of origin of bulk milk

The fatty acid composition of cow milk, collected in a survey from 19 dairy farms in the border area between Italy and Slovenia, was investigated for 2 consecutive years (2005 and 2006) to assess the possibility of discriminating the area of the origin of the milk. Farms were selected based on diet, animal breed, and farm management to represent the local variability of the systems. In Slovenian farms, grass silage and hay prevailed over corn silage and concentrate feeds, whereas in Italian farms, hay and concentrates were the predominant components of the diet. Fifty-three fatty acids were separated and quantified in Italian and Slovenian milks. Saturated fatty acids represented the most abundant class, followed by monounsaturated and polyunsaturated fatty acids. Significant differences were observed between Italian and Slovenian milks for the concentration of 40 fatty acids, whereas significant differences were observed between years of production for 15 fatty acids. Discriminant analysis was used to identify a classification criterion of milk, using country and year of production as grouping variables. Considering statistical results and the scatter plot of the scores of the first 2 functions, the best discriminant criteria were those based on unsaturated fatty acids and on fatty acids with several carbon atoms ≥18.     

Milk from cows fed a diet with a high forage:concentrate ratio improves inflammatory state,oxidative stress,and mitochondrial function in rats

Excessive energy intake may evoke complex biochemical processes characterized by inflammation, oxidative stress, and impairment of mitochondrial function that represent the main factors underlying noncommunicable diseases. Because cow milk is widely used for human nutrition and in food industry processing, the nutritional quality of milk is of special interest with respect to human health. In our study, we analyzed milk produced by dairy cows fed a diet characterized by a high forage:concentrate ratio (high forage milk, HFM). In view of the low n-6:n-3 ratio and high content of conjugated linoleic acid of HFM, we studied the effects of this milk on lipid metabolism, inflammation, mitochondrial function, and oxidative stress in a rat model. To this end, we supplemented for 4 wk the diet of male Wistar rats with HFM and with an isocaloric amount (82 kJ, 22 mL/d) of milk obtained from cows fed a diet with low forage:concentrate ratio, and analyzed the metabolic parameters of the animals. Our results indicate that HFM may positively affect lipid metabolism, leptin:adiponectin ratio, inflammation, mitochondrial function, and oxidative stress, providing the first evidence of the beneficial effects of HFM on rat metabolism.     

Production response of multiparous Holstein cows treated with bovine somatotropin and fed diets enriched with n-3 or n-6 fatty acids

Multiparous cows (n = 59) were blocked by expected calving date and previous milk yield and assigned randomly to treatments to determine the effects of bovine somatotropin (bST; Posilac, Monsanto Animal Agricultural Group, St. Louis, MO) and source of dietary fat on production responses. Diets were provided from calving and included whole, high-oil sunflower seeds [SS; 10% of dietary dry matter (DM); n-6:n-3 ratio of 4.6] as a source of linoleic acid (18:2) or a mixture of Alifet-High Energy and Alifet-Repro (AF; Alifet USA, Cincinnati, OH; 3.5 and 1.5% of dietary DM, respectively; n-6/n-3 ratio of 2.6) as a source of protected n-3 fatty acids. Diets contained 181 versus 188 g of crude protein and 183 versus 186 g of acid detergent fiber/kg of DM and 1.54 versus 1.66 Mcal of net energy for lactation at the actual DM intake for SS versus AF, respectively. Cows received 0 or 500 mg of bST every 10 d from 12 to 70 d in milk (DIM) and at 14-d intervals through 280 DIM. The 2 × 2 factorial combination of diet (SS or AF) with or without bST administration resulted in treatments designated as SSY, SSN, AFY, and AFN, respectively. Data were analyzed as repeated measures using mixed model procedures to determine the effects of diet, bST, and their interactions. Yield of 3.5% fat-corrected milk was not altered by diet, but was increased by 4.0 ± 1.9 kg/d from 12 to 70 DIM and by 5.1 ± 1.2 kg/d from 12 to 280 DIM by bST. Treatment did not affect DM intake or energy balance (EB) nadir. There was an interaction of bST and diet on EB because AF decreased the impact of bST on overall EB and allowed AFY cows to reach a positive EB earlier than SSY cows. Gross feed efficiency adjusted for body weight change was greater for bST-treated cows (1.03 vs. 1.15 ± 0.03 kg of fat-corrected milk/Mcal of net energy for lactation). Circulating insulin-like growth factor-I concentrations were increased by bST (85 vs. 125 ± 8 ng/mL). Body weight, body condition score, and backfat thickness were reduced by bST, but differences between treated and nontreated cows did not differ by 280 DIM. Results indicate cows responded to bST administration in early lactation, but the magnitude of the response was greater after 70 DIM. Source of dietary fat had a minimal effect on most production measurements, but relative to SS, AF decreased the impact of bST on overall EB. Results support the premise that bST administration prolongs the delay in postpartum tissue replenishment.     

Potentials to differentiate milk composition by different feeding strategies

To investigate the effect of the dietary intake of the cow on milk composition, bulk-tank milk was collected on 5 occasions from conventional (n = 15) and organic (n = 10) farms in Denmark and on 4 occasions from low-input nonorganic farms in the United Kingdom, along with management and production parameters. Production of milk based on feeding a high intake of cereals, pasture, and grass silage resulted in milk with a high concentration of α-linolenic acid (9.4 ± 0.2 mg/kg of fatty acids), polyunsaturated fatty acids (3.66 ± 0.07 mg/kg of fatty acids), and natural stereoisomer of α-tocopherol (RRR-α-tocopherol, 18.6 ± 0.5 mg/kg of milk fat). A milk production system using a high proportion of maize silage, by-products, and commercial concentrate mix was associated with milk with high concentrations of linoleic acid (LA; 19.7 ± 0.4 g/kg of fatty acids), monounsaturated fatty acids (27.5 ± 0.3 mg/kg of fatty acids), and a high ratio between LA and α-linolenic acid (4.7 ± 0.2). Comparing these 2 production systems with a very extensive nonorganic milk production system relying on pasture as almost the sole feed (95 ± 4% dry matter intake), it was found that the concentrations of conjugated LA (cis-9,trans-11; 17.5 ± 0.7 g/kg of fatty acids), trans-11-vaccenic acid (37 ± 2 g/kg of fatty acids), and monounsaturated fatty acids (30.4 ± 0.6 g/kg of fatty acids) were higher in the extensively produced milk together with the concentration of antioxidants; total α-tocopherol (32.0 ± 0.8 mg/kg of milk fat), RRR-α-tocopherol (30.2 ± 0.8 mg/kg of milk fat), and β-carotene (9.3 ± 0.5 mg/kg of milk fat) compared with the organic and conventional milk. Moreover, the concentration of LA (9.2 ± 0.7 g/kg of fatty acids) in milk from the extensive milk production system was found to approach the recommended unity ratio between n-6 and n-3, although extensive milk production also resulted in a lower daily milk yield.     

Comparison of supplementation of n-3 fatty acids from fish and flax oil on cytokine gene expression and growth of milk-fed Holstein calves

The ability to reduce incidence of disease in calves and improve early vaccination strategies is of particular interest for dairy producers. The n-3 fatty acids have been reported to reduce inflammatory diseases in humans but limited research has been done in calves. The objective of this study was to compare supplementation of n-3 fatty acids from fish and flax oil on gene expression of whole blood cells and growth of milk-fed Holstein calves. Forty-eight Holstein bull calves from a commercial dairy were randomly assigned to 1 of 3 diets beginning at 4 d old: (1) control milk replacer (MR) with all pork fat, (2) MR with 2% flax oil, and (3) MR with 2% fish oil. All MR were 17% fat, 27% crude protein on a dry matter (DM) basis, with all protein from whey sources. Calves were each fed 654 g DM of MR daily for the first 25 d and then 327 g/d for d 26, 27, and 28. On d 28, calves were challenged with a Pasteurella vaccine and the temperature response to the vaccine was recorded. Milk and feed intake and fecal scores were recorded daily, and body weight and hip width were recorded weekly. Blood was collected from all calves on d 25. One tube of collected blood was incubated with endotoxin (lipopolysaccharide; LPS) for 2 h and frozen with a second tube of control blood. Quantitative real-time PCR was used to assess the effects of LPS stimulation on cytokine gene expression. During the 28 d, calves supplemented with flax oil had a greater growth rate and feed efficiency than calves fed fish oil (0.52 ± 0.02 vs. 0.48 ± 0.02 g of gain:g of feed). Fish oil tended to decrease LPS stimulation of tumor necrosis factor-α expression. Flax oil, but not fish oil, decreased the expression of IL-4 and tended to decrease expression of osteopontin and IL-8. Flax oil tended to reduce the increase in rectal temperature in response to a Pasteurella vaccine. In conclusion, our data support the idea that supplementation with n-3 fatty acids affects cytokine gene expression.     

Increasing dietary levels of docosahexaenoic acid-rich microalgae: Ruminal fermentation,animal performance,and milk fatty acid profile of mid-lactating dairy cows

This study aimed to evaluate the effects of increasing dietary levels of microalgae (ALG), rich in docosahexaenoic acid (DHA; All-G-Rich, Alltech, Nicholasville, KY), in isolipidic diets, on animal performance, nutrient digestibility, ruminal fermentation, milk fatty acid profile, energy balance, microbial protein synthesis, and blood serum metabolites in mid-lactating dairy cows. Twenty-four Holstein cows [130.3 ± 15.4 d in milk, and 30.8 ± 0.543 kg/d of milk yield (mean ± standard error)] were used in a 4 × 4 Latin square design experiment to evaluate the following treatments: control diet, without addition of ALG; and increasing levels of ALG [2, 4, and 6 g/kg of dry matter (DM)]. The ALG decreased DM intake and increased total-tract DM apparent digestibility. A tendency was observed for a quadratic effect on total-tract NDF digestibility by ALG inclusion, with peak value of the quadratic response at 4.13 g/kg of DM dose. Moreover, ALG increased ruminal pH and decreased acetate and total volatile fatty acid concentrations. Fat-corrected milk and energy-corrected milk were quadratically affected, and a tendency for a milk yield effect was observed when ALG levels increased, whereas maximal yields were observed with intermediate doses. Milk fat, protein, and lactose concentrations were diminished, whereas productive efficiency was improved by the increase of ALG levels. Saturated fatty acid proportions were decreased, whereas polyunsaturated fatty acid proportions were increased when ALG was fed. There was low DHA transfer into milk; however, ALG inclusion decreased C18:0, C18:1 cis-9, C18:2 cis-9,12, and C18:3 cis-9,12,15 proportions, and increased C18:2 cis-9,trans-11, C18:1 trans-9, and C18:1 trans-11 proportions. Gross energy intake was decreased, whereas no effect was observed on digestible, metabolizable, or net energy intake. The ALG inclusion quadratically affected the microbial protein synthesis, with maximal enhancement at 3.24 g/kg of DM dose, and also increased serum cholesterol concentration. Under the conditions of this experiment, the inclusion of ALG in diets for mid-lactating dairy cows decreased feed intake and increased nutrient digestibility, improving productive efficiency and modifying milk fatty acid profile. Estimated intermediate doses (1.22 to 2.90 g/kg of DM) of DHA-rich ALG may be beneficial to milk, fat-corrected milk, and energy-corrected milk yields, and is recommended for dairy cows.     

Plant polyphenols associated with vitamin E can reduce plasma lipoperoxidation in dairy cows given n-3 polyunsaturated fatty acids

Diets rich in n-3 polyunsaturated fatty acids (PUFA) improve the nutritional value of ruminant products but also increase the risk of lipoperoxidation in plasma and tissues. The relative effectiveness of dietary antioxidants such as vitamin E (vit E) given alone or with plant extracts rich in polyphenols (PERP) containing rosemary, grape, citrus, and marigold was investigated in the plasma of mid-lactation dairy cows given diets enriched in 18:3 n-3. For a 30-d period, the animals were given a maize silage-based diet (control group C, n = 6) or the same basal diet supplemented with extruded linseed rich in 18:3 n-3 [50 g of oil/kg of diet dry matter (DM); group L, n = 6], extruded linseed + vit E (375 international units/kg of diet DM; 7,500 IU/cow per day; group LE, n = 6), or extruded linseed + vit E + PERP (10 g/kg of diet DM; group LEP, n = 5). Plasma susceptibility to lipoperoxidation was evaluated using in vitro parameters of conjugated diene formation (lag phase and maximum oxidation rate). Plasma indicators of lipoperoxidation and antioxidant status were analyzed in the 4 experimental groups as well as the fatty acid (FA) composition of total plasma lipids. At d 30, group L significantly increased plasma cholesterol esters (+57%) and phospholipids (+35%) compared with group C. It also increased plasma n-3 PUFA (4.7-fold increase) to the detriment of n-6 PUFA (−30%), leading to a higher peroxidizability index (+20%). Plasma in vitro lipoperoxidation was higher in group L (rich in 18:3 n-3) than in group C. Vitamin E alone had no effect on lipoperoxidation, whereas vit E in association with PERP lowered lipoperoxidation by increasing the resistance time against peroxidation (+47%) and by decreasing the oxidation rate (−48%) compared with group L at d 30. Surprisingly, in vivo plasma lipoperoxidation estimated by the plasma level of the major lipoperoxidation product (malondialdehyde) was not significantly increased in group L. This study shows, for the first time, that PERP supplied in association with vit E were able to reduce lipoperoxidation in lactating cows given a diet rich in 18:3 n-3, thereby helping to protect cows against the deleterious consequences of lipoperoxidation and potentially ensuring antioxidant potential for 18:3 n-3–enriched dairy products.