奶山羊乳房炎抗氧化性微量元素质量浓度的变化

为探讨奶山羊泌乳期乳房炎抗氧化性微量元素质量浓度的变化,实验测定了乳房炎奶山羊血清和乳腺组织中的Se,Zn,Cu的质量浓度.结果表明,患病奶山羊血清和乳腺组织中Se和Zn质量浓度明显低于正常对照组(P<0.05,P<0.01),Cu含量高于正常对照组(P>0.05).患病奶山羊血清和乳腺组织中Se和Zn质量浓度的减少降低了抗氧化能力及机体抵抗力,铜质量浓度升高的机理目前尚不十分清楚.     

中草药添加剂对泌乳期奶山羊抗氧化能力的影响

为探讨中草药添加剂对泌乳期奶山羊抗氧化能力的影响,实验测定了奶山羊血清和乳腺组织中的超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）、过氧化氢酶（CAT）活性和丙二醛（MDA）质量分数。结果表明,中药组奶山羊血清和乳腺组织中SOD、GSH-Px和CAT活性高于或显著高于正常对照组（P〉0．05,P〈0．05,P〈0．01）,MDA质量分数低于或显著低于正常对照组（P〉0．05,p〈0．05,P〈0．01）。中草药添加剂能减少脂质过氧化产物MDA的生成,同时提高奶山羊抗氧化酶活性,增强了奶山羊的抗氧化能力。     

蛋白质羰基含量与蛋白质氧化损伤

本文讨论了蛋白质羰基含量与蛋白质氧化损伤的关系及其在抗氧化领域中的应用，以便为进一步完善抗氧化保健食品功能检测方法提供理论依据。     

甘谷二肽的抗氧化活性及氧化损伤的保护作用

以N-叔丁氧羰基-甘氨酸和N′-三苯甲基-L-谷氨酰胺为原料,以氯甲酸异丁酯为酸酐,采用混合酸酐法合成甘谷二肽,利用红外光谱进行表征,并探究甘谷二肽的还原能力、对DPPH·、·OH、·O^-₂的清除能力及对线粒体和蛋白质氧化损伤的保护作用。结果表明：合成产物在1 699.67 cm^-1处出现酰胺键C═O的伸缩振动,为甘谷二肽;甘谷二肽具有较强的·OH和·O^-₂清除能力,其·OH和·O^-₂的IC₅₀分别为0.625、5.108 mg/mL,但对DPPH·的清除能力及还原能力效果较差;甘谷二肽能够抑制线粒体氧化损伤和蛋白质氧化损伤。     

山核桃加工过程脂肪酸氧化及抗氧化能力变化研究

试验选取浙江临安山核桃加工过程样品。研究了山核桃原料脂肪酸组成和相对质量分数以及加工过程中4种主要脂肪酸氧化规律及抗氧化能力变化情况。结果表明:山核桃脂肪酸组分共确认13种,其中油酸(C18∶1)、亚油酸(C18∶2)、棕榈酸(C16∶0)、亚麻酸(C18∶3)为山核桃中最主要的4种脂肪酸;加工过程4种主要脂肪酸含量均呈缓慢下降趋势,其中亚油酸、亚麻酸在蒸煮阶段下降速度最快,棕榈酸则在第一次炒制阶段含量下降最快;蒸煮工序对抗氧化能力影响最大;山核桃细胞脂滴在蒸煮后即发生破裂,之后随着加工过程扩散融合。试验结果显示山核桃脂肪酸氧化在加工过程持续发生,长时间高温促进氧化加剧,自身抗氧化能力则逐渐下降,细胞结构破坏。     

乳房炎和体细胞的计数

乳房炎概述乳房炎是引起乳牛产奶量大大降低的一种疾病,它是一种由不同形式的致病菌引起的乳房感染。造成乳房炎的致病菌百分之九十从属于下列菌群: 1.金黄色葡萄球菌(Staphaureus) 2.无乳链球菌(Strepagalactiae) 3.停乳链球菌(Strepdysgalactioae)     

油脂氧化与抗氧化技术

对油脂贮存过程中的氧化机理、氧化反应历程和产物进行了分析,介绍了油脂抗氧化技术的原理和常用抗氧化剂的性能,提出应科学合理地使用抗氧化剂,减缓油脂氧化,保证油脂的食用安全。     

山楂不同溶剂提取物的抗氧化活性及对DNA和蛋白质氧化损伤的保护作用

研究山楂甲醇、乙醇、丙酮、乙酸乙酯、氯仿、石油醚等不同极性溶剂提取物的总多酚、总黄酮含量及其成分组成,并分析比较不同提取物的体外抗氧化活性及其对DNA和蛋白质氧化损伤的保护效果。结果表明,山楂的不同溶剂提取物中总多酚、总黄酮含量及其生物活性不同。其中,甲醇提取物中总多酚和总黄酮含量均最高,清除DPPH自由基、ABTS自由基能力和铁还原能力最强,对蛋白质和DNA氧化损伤的保护作用亦优于其他提取物。山楂甲醇提取物主要活性成分为表儿茶素、原花青素B2、绿原酸和槲皮素。山楂提取物的总多酚、总黄酮含量与其抗氧化活性、DNA和蛋白质氧化损伤的保护效果均具有较高的相关性。     

水飞蓟油的体外抗氧化活性及对氧化损伤小鼠的保护作用

目的：研究水飞蓟油的体外抗氧化活性及其对D-半乳糖氧化损伤小鼠的保护作用。方法：通过测定水飞蓟 油对二苯基苦味酰基苯肼自由基、羟自由基的清除能力及其总抗氧化力,研究其体外抗氧化活性;通过测定水飞蓟 油对氧化损伤小鼠血清抗氧化酶活力以及其对小鼠肝组织形态的影响,研究其对氧化损伤小鼠的保护作用。结果： 水飞蓟油具有一定的体外抗氧化能力,并与其质量浓度呈一定的正相关关系;水飞蓟油可显著提高小鼠血清中超氧 化物歧化酶和谷胱甘肽过氧化物酶的活力及总抗氧化能力,可以保护小鼠肝细胞形态的完整性。结论：水飞蓟油具 有一定的体外抗氧化活性,对D-半乳糖氧化损伤小鼠具有明显的保护作用。     

Quantification of milk yield and composition changes as affected by subclinical mastitis during the current lactation in sheep

The aim of this work was to quantify, on a half-udder basis, the changes in ewe milk yield and composition caused by unilateral subclinical mastitis within the current lactation. Fluctuations due to production level, infection severity, time from the onset of infection, and lactation curves were also studied. Yield and composition of milk from half-udders of unilateral infected ewes were compared between them and with a set of healthy halves using a mixed model. The experiment was completed with a whole-udder approach on the same animals. To test the effect of intramammary infection (IMI) in the 7 wk following the onset of infection, 20 ewes that acquired unilateral subclinical mastitis during lactation and 40 healthy ewes were used. Another group of 20 unilaterally infected ewes from wk 1 of lactation and other 40 healthy ewes were studied to test the effect of IMI on lactational milk yield and composition. The individual milk loss in ewes infected during lactation was 15% for the 7 wk following the onset of infection, and 6.6% more milk was produced by the uninfected half to compensate milk lost by the infected half. Lactational milk yield loss in ewes infected from wk 1 postpartum was 17%. The changes in milk yield were noticed from the week of infection diagnosis. The production level of animals influenced the milk yield changes caused by IMI in such a way that the more productive ewes lost more milk, although these losses were proportional to their production level. On the other hand, infection severity affected milk loss between glands, being more pronounced as somatic cell count increased. A clear decrease of lactose content and casein:protein ratio due to subclinical IMI was observed and it remained throughout the postinfection period. Improving udder health status is necessary to maintain milk production and quality in dairy ewes during lactation.     

Somatic cell count distributions during lactation predict clinical mastitis

This research investigated somatic cell count (SCC) records during lactation, with the purpose of identifying distribution characteristics (mean and measures of variation) that were most closely associated with clinical mastitis. Three separate data sets were used, one containing quarter SCC (n = 1444) and two containing cow SCC (n = 933 and 11,825). Clinical mastitis was defined as a binary outcome, present or absent, for each lactation, and SCC were log (base 10) transformed. A generalized linear mixed model within a Bayesian framework was used for analysis. Parameters were estimated using Markov Chain Monte Carlo with Gibbs sampling. Results from the 3 data sets were similar. Increased maximum and standard deviation log SCC during lactation, rather than increased geometric mean, were the best overall indicators of clinical mastitis. Distributions of SCC were also investigated separately for different mastitis pathogens. Increased maximum log SCC was associated with clinical mastitis caused by all pathogen types. Increased standard deviation log SCC was associated with Staphylococcus aureus, and Streptococcus uberis clinical mastitis and increased coefficient of variation log SCC (standard deviation divided by mean) was associated with Escherichia coli clinical mastitis. Increased geometric mean lactation SCC was associated with an increased risk of Staph. aureus clinical mastitis but a reduced risk of E. coli clinical mastitis. Our results suggest that using measures of variation and maximum cow SCC would enhance the accuracy of predicting clinical mastitis, compared with geometric mean SCC, and therefore improve genetic programs that aim to select for clinical mastitis resistance. The results are also consistent with low SCC increasing susceptibility to some mastitis pathogens.     

Developmental changes in proteins of casein micelles in goat milk using data-independent acquisition-based proteomics methods during the lactation cycle

Casein micelles (CM) play an important role in milk secretion, stability, and processing. The composition and content of milk proteins are affected by physiological factors, which have been widely investigated. However, the variation in CM proteins in goat milk throughout the lactation cycle has yet to be fully clarified. In the current study, milk samples were collected at d 1, 3, 30, 90, 150, and 240 of lactation from 15 dairy goats. The size of CM was determined using laser light scattering, and CM proteins were separated, digested, and identified using data-independent acquisition (DIA) and data-dependent acquisition (DDA)-based proteomics approaches. According to clustering and principal component analysis, protein profiles identified using DIA were similar to those identified using the DDA approach. Significant differences in the abundance of 115 proteins during the lactation cycle were identified using the DIA approach. Developmental changes in the CM proteome corresponding to lactation stages were revealed: levels of lecithin cholesterol acyltransferase, folate receptor α, and prominin 2 increased from 1 to 240 d, whereas levels of growth/differentiation factor 8, peptidoglycan-recognition protein, and 45 kDa calcium-binding protein decreased in the same period. In addition, lipoprotein lipase, glycoprotein IIIb, and α-lactalbumin levels increased from 1 to 90 d and then decreased to 240 d, which is consistent with the change in CM size. Protein–protein interaction analysis showed that fibronectin, albumin, and apolipoprotein E interacted more with other proteins at the central node. These findings indicate that changes in the CM proteome during lactation could be related to requirements of newborn development, as well as mammary gland development, and may thus contribute to elucidating the physical and chemical properties of CM.     

Influence of subclinical mastitis during early lactation on reproductive parameters.

Our objective was to determine the effects of mastitis during early lactation on the reproductive performance of Jersey cows. From 1986 to 1997, quarter foremilk samples were collected every 4 to 8 wk during lactation, at drying off, near calving, and when clinical mastitis was diagnosed and were evaluated microbiologically to identify causative bacteria. Services per conception, days open, and days to first service were obtained from DHIA records on 752 cows. Cows were separated by mastitis type (clinical, n = 186; subclinical, n = 240; control, uninfected or infected after confirmed pregnancy, n = 326). Cows were reclassified based on the time of clinical or subclinical mastitis as follows: period 1, before first service (n = 374); period 2, between first service and pregnancy (n = 52); and period 3, after confirmed pregnancy or uninfected (control; n = 326). Milk production did not differ for any group separations. Reproductive performance did not differ between gram-negative or gram-positive mastitis pathogens. Cows with clinical or subclinical mastitis before first service had increased days to first service (77.3+/-2.7 and 74.8+/-2.7 d), days open (110.0+/-6.9 and 107.7+/-6.9 d), and services per conception (2.1+/-0.2 and 2.1+/-0.2) compared with controls (67.8+/-2.2 d, 85.4+/-5.8 d, 1.6+/-0.2; P < 0.05). Days to first service were not increased in cows with clinical or subclinical mastitis during period 2 (70.6+/-3.3 and 61.2+/-7.8 d). However, days open (143.6+/-8.5 d) and services per conception (3.0+/-0.2) were increased (P < 0.05) in cows with clinical mastitis during period 2, but not in cows with subclinical mastitis (90.9+/-20.2 d and 2.1+/-0.5). Cows initially diagnosed subclinical that became clinical during period 2 exhibited increased days to first service (93.9+/-10.1 d), days open (196.0+/-26.2 d), and services per conception (4.3+/-0.7) compared with control animals (P < 0.05). In conclusion, subclinical mastitis reduced reproductive performance of lactating cows similar to clinical mastitis. Subclinical mastitis followed by clinical mastitis resulted in the most severe loss in reproductive performance.     

Measurement of mastitis in first lactation heifers and third to fourth lactation cows

The influence of lactation stage on susceptibility to mastitis infection in Friesian dairy cows was investigated. The cattle studied included third to fourth lactation cows and both summer and autumn calving groups of heifers. No increase in vulnerability to invasion by mastitis pathogens in recently calved cattle was demonstrated. Analysis of raw milk samples using ATP bioluminescence produced variation in results, suggesting that further work to develop the technique is required.     

Deferoxamine reduces tissue damage during endotoxin-induced mastitis in dairy cows

The protective effects of 3 antioxidants on polymorphonuclear neutrophil-induced damage to mammary cells were evaluated in vivo using an endotoxin-induced mastitis model. Fifteen healthy, midlactation cows with no history of clinical Escherichia coli mastitis were randomly assigned to 1 of the 3 treatment groups corresponding to each modulator to be evaluated, that is, deferoxamine, catechin, and glutathione ethyl ester. Each cow had 1 quarter infused with saline and 1 quarter infused with the selected modulator; a third quarter was infused with lipopolysaccharides (LPS), whereas the fourth quarter received a combination of LPS and the modulator. Infusion of LPS caused acute mastitis as determined by visual observations and by large increases in milk somatic cell count, BSA, and proteolytic activity. These parameters were not affected by antioxidant administration. The extent of cell damage was evaluated by measuring milk levels of lactate dehydrogenase and N-acetyl-β-_D-glucosaminidase activity. Levels of these parameters were several times higher after LPS administration. Intramammary infusions of catechin or glutathione ethyl ester did not exert any protective effect, whereas infusion of deferoxamine, a chelator of iron, decreased milk lactate dehydrogenase and NA-Gase activity, suggesting a protective effect against neutrophil-induced damage. The protective effect of deferoxamine was also evidenced by a lower milk level of haptoglobin. The proteolytic activity of mastitic milk was not influenced by the presence of deferoxamine. Overall, our results suggest that local infusion of deferoxamine may be an effective tool to protect mammary tissue against neutrophil-induced oxidative stress during bovine mastitis.     

Diversity of dairy goat lactation curves in France

A high level of production at the peak of lactation may be associated with animal health disorders, high feeding costs, and reduced milk supply throughout the year. The objective of this study was to typologize the lactation curves in French dairy goats and analyze the influence of environmental and genetic factors on these curves. The data set consisted of 2,231,720 monthly test-day records of 213,534 French Saanen and Alpine goats recorded between September 2008 and June 2012. First, principal component analysis classified the shape of the lactation curves into 3 principal components: the first component accounted for milk yield level throughout lactation, the second component accounted for lactation persistency, and the third component accounted for milk yield in mid-lactation. Then, from the principal component scores, the lactations were clustered into 5 different groups. Most lactations had a similar shape to the mean curve, except 30% of the lactations that fell into 3 clusters that had a high production level at the peak and then a different persistency according to cluster. Estimated breeding value for milk yield and home region of breeding were the factors most related to lactation production level. Month of kidding, breed, and gestation stage had the biggest effect on persistency. Month of kidding was the factor most strongly linked to mid-lactation production. A herd effect was observed on all 3 principal components.     

Quality and microstructural changes in goat meat during heat treatment

Environmental scanning electron microscopy (ESEM) was used to study the structure of the semi-membranous muscle of goat meat during heat treatment. The four treatments examined were raw (control), conventional heating, domestic microwave heating and industrial microwave heating. The ESEM showed shrinkage and denaturation in muscle fibers after cooking by the various methods. No surface damage was observed in any image for conventional heating. More structural damage was observed in microwave heating at both domestic (700 W) and industrial (12,000 W) levels. The pattern of distribution in microwave heating caused surface damage to muscle fiber with separation of some portions and denaturation of collagen.