果味剂对奶风味及奶牛生产性能的影响

试验选择了24头泌乳前中期的同一胎次、健康无病、具有相近体重、产奶量与泌乳期的荷斯坦奶牛,将其分为4组,每组6头牛,在奶牛日粮中添加苹果味果味剂、香蕉味果味剂、混合香型果味剂,并设置对照组(不添加果味剂)进行奶牛饲养试验。对奶牛的生产性能以及奶样中风味物质进行评定。试验结果表明:①在奶牛生产性能方面,与对照组相比,3种果味剂都有减缓产奶量下降的趋势,其中香蕉味的作用效果最好(产奶量下降:香蕉味0.5%,苹果味11.9%,混合味8.86%,对照13.5%)。②对奶样进行感官评价,在单独的色泽、组织状态、奶香味、果香味、甜味、酸味、苦味、涩味、饲草味和牛体味中,4种样品基本没有差异,4个样品的综合风味存在显著差异(P<0.05),在风味的总得分上,混合风味>苹果风味>香蕉风味=对照组。     

Changes in the milk composition of okapi (Okapia johnstoni) during the first 6 months of lactation

We collected 17 milk samples at 1 day to 6 months post partum from one captive okapi (Okapia johnstoni). Milks were examined for nutrient composition, including water, fat, crude protein, carbohydrates, ash and five minerals. The average values of the concentrations were 79.2 ± 3.0% SD water, 8.5 ± 3.4% fat, 7.5 ± 1.1% crude protein, 3.6 ± 0.6% carbohydrate, 1.2 ± 0.1% ash, 263.7 ± 47.3 mg/100 g calcium, 183.0 ± 40.0 mg/100 g phosphorus, 95.2 ± 17.6 mg/100 g sodium, 74.4 ± 34.3 mg/100 g potassium and 28.4 ± 4.4 mg/100 g magnesium, respectively. The protein concentration increased at late lactation (P < 0.01). The contents of sodium and potassium were rather high in the early lactation period, while those of calcium and phosphorus were rather low in the early lactation period. During the course of lactation in the first week post partum and the protein concentration was high at 1 day post partum. We compare our findings with the American Association of Zoos & Aquariums's Okapi Species Survival Plan Hand‐rearing Protocol, and recommend that nutrient composition of the formula for okapi calves is developed using the present study as a guide.     

牛奶质量安全主要风险因子分析 Ⅲ .兽药残留

作者对主要乳品贸易国家和国际组织所规定的牛奶中兽药最大残留限量、检测方法、风险评估模式进行了综述,分析了中国与其他国家和组织在兽药限量规定上的异同及原因,并就完善中国牛奶中兽药残留限量规定和风险控制提出了建议。     

生乳的质量安全及其影响因素的研究进展

生乳的质量安全一直以来是人们关注的焦点,加强生乳质量安全监管,确保生乳质量安全,保障消费者身体健康显得尤为重要。作者对优质安全生乳的内涵、影响因素、管理与控制措施等方面进行了综述,以期为生产和管理提供参考。     

饲料中适量添加小苏打对牦牛产奶性能的影响

研究在牦牛饲料中适量添加小苏打后,对牦牛产奶量及相关指标的影响。试验结果表明,与对照组相比,3个试验组牦牛产奶量变化不显著,试验前后牦牛奶的pH值也变化不显著,但是试验1组、试验2组、试验3组牦牛乳中的乳脂率有显著提高,分别提高了2.52%、2.95%、3.08%。     

Preparation and Properties of Plywood Adhesives with Soy Protein Isolate Modified by SDS

The effects of mass concentration,the reaction temperature and the reaction time of soy protein isolate(SPI) and sodium dodecyl sulfate (SDS) on the adhesive strength of the modified SPI adhesives has been studied through orthogonal experiments.And the adhesive mechanism of the modified SPI adhesives was discussed.The results show that the optimum formula conditions are as follows:mass concentration of SPI was 14%,that of SDS 1%,reaction temperature 35℃and the reaction time 3 h.Under the optimum conditions, the dry adhesive strength of the modified SPI adhesives was 1.82 MPa,the wet adhesive strength was 0.82 MPa,the viscosity was 5.8 Pa·s,the solid content was 12.96%.After SDS was added into SPI, the composites of SDS-SPI were formed,the internal hydrophobic groups among the SPI molecule structure were turned out and the water resistance of the modified SPI adhesives was enhanced with an increase of the modification time.When the concentration of SDS was over a defined value,the disulfide bond was broken and the modification effect of SDS went bad.     

全棉籽对奶牛生产性能及血清生化指标的影响

本试验旨在研究饲粮中添加全棉籽对奶牛生产性能及血清生化指标影响.试验采用4×4拉丁方设计,选择8头泌乳早期的经产中国荷斯坦奶牛,随机分为4组,每组2个重复,每个重复1头牛.A组为对照组,饲喂基础饲粮;B、C和D组分别饲喂含5％、10％和15％全棉籽的试验饲粮.共进行4期试验,每期试验28 d,其中预试期7d,正试期21 d.结果表明:1)随着全棉籽比例的增加,奶牛产奶量有提高趋势,奶牛的乳脂率和4％标准乳产量显著提高(P＜0.01),但全棉籽对乳蛋白率、乳糖率和乳非脂固形物率无显著影响(P＞0.05).2)全棉籽对粗蛋白质、粗脂肪、酸性洗涤纤维的表观消化率无显著影响(P＞0.05),但含有全棉籽饲粮的中性洗涤纤维的表观消化率均高于对照组(P＜0.05),其中C组比对照组提高了8.4％(P＜0.05).3)全棉籽对奶牛血清中白蛋白、血糖含量无显著影响(P＞0.05),对血清胆固醇和尿素氮含量影响显著(P＜0.05).C组奶牛血清中胆固醇含量显著低于其他各组(P＜0.01).B、C组的血清尿素氮含量显著低于对照组和D组.4)随着饲粮中全棉籽比例的提高,血清和乳中游离棉酚含量也显著提高(P＜0.01),乳中游离棉酚含量在各试验组间差异不显著(P＞0.05).结果提示,全棉籽在奶牛泌乳早期饲粮中的最适添加量为10％.     

TMR中物理有效中性洗涤纤维对奶牛产奶性能的影响

本文旨在研究不同物理有效中性洗涤纤维水平的TMR日粮对奶牛瘤胃消化性能的影响。选取3头体重为（650±10）kg的荷斯坦奶牛,采用3×3拉丁方试验设计,三种试验日粮精料补充料完全相同,粗饲料由长度不同的玉米青贮和羊草配制而成的三种peNDF水平的日粮,即I组（长度为5cm-7cm）、II组（长度为3cm-5cm）、III组（长度为1cm-2cm）。试验分三期,每期试验共17天。试验结果表明：随着物理有效中性洗涤纤维含量的增加,I组、Ⅱ组、Ⅲ组的产奶量差异不显著,I组、Ⅱ组的乳脂率与4％标准乳显著高于Ⅲ组,I组与Ⅱ组之间差异不显著。结果显示,荷斯坦奶牛TMR日粮中不同物理有效中性洗涤纤维的含量对奶牛的产奶量影响不大,但是会影响到奶牛的乳脂率及4％标准乳的含量,综合本试验结果建议奶牛TMR日粮中粗饲料的长度在3cm-5cm较为适宜。     

Searching for DNA markers for milk production and composition on chromosome 6 in sheep

Several milk protein polymorphisms are potential tools for selection in dairy ruminants. However, research results for dairy sheep are not as conclusive as those for goats or cattle and are often controversial. The main objective of this study was to find and later use molecular genetic markers in selection to improve milk production and milk composition in Awassi ewes. Chromosome 6 was chosen because several studies have reported the presence of significant quantitative trait loci (QTL) affecting milk production traits on ovine and bovine chromosome 6. Altogether, genotypes for 13 microsatellite loci were determined for 258 ewes, which were purebred Awassi or Awassi-Merino crosses. Phenotypic data were lactation yield of milk, milk fat, protein and lactose (kg), average milk protein and fat percentage and average somatic cell count. Five out of the 13 microsatellites showed significant association with at least one of the examined traits.     

The evaluation of the curd forming ability of milk replacers

Inadequate milk curd formation in the abomasum of newborn calves causes malnutrition and diarrhea. In order to define the factors of inadequate curd formation, we compared the curd forming ability among 9 kinds of milk replacers, bulk milk (raw milk), and skim milk both in vitro and in vivo . When rennet was added, the raw milk and one milk replacer formed firm curds. The rest of the milk replacers and skim milk did not form any curd. When a solution of HCl was added, raw milk, three milk replacers and skim milk formed the curd at pH 4.5, but the other milk replacers did not. When HCl was added following the rennet, raw milk, one milk replacer and skim milk formed the curd. In vivo , raw milk, two milk replacers and skim milk showed good curd formation whereas the other milk replacers showed poor curd formation inside the abomasums of the calves. This study showed that most of the milk replacers sold in Japan could not form the curd with rennet.