放养密度对泌乳奶牛氧化应激状态和乳腺通透性的影响

研究旨在探讨放养密度对早期泌乳奶牛氧化应激状态和乳腺通透性的影响。试验选择32头泌乳期奶牛,根据奶次和产奶量随机为为2组,每组16头牛,每个重复1头牛。奶牛采用两种放养方式,即75%的放养密度和100%放养密度,试验共开展8周,且试验期间两组奶牛饲喂相同的饲料。结果显示:75%较100%放养密度组显著提高了泌乳量、能量校正乳和4%脂肪校正乳产量(P<0.05),同时75%放养密度组显著降低了乳中尿素氮含量(P<0.05),显著提高了整个试验期间乳中蛋白质含量(P<0.05),而100%放养密度组较75%放养密度组显著提高了奶牛乳中体细胞数量(P<0.05)。75%放养密度组血清乳糖含量显著低于100%放养密度组(P<0.05),75%放养密度组较100%放养密度组显著提高了血清SOD和T-AOC活力(P<0.05)。75%放养密度组血清胰岛素及胰岛素与胰高血糖素比值最低(P<0.05),但催乳素和生长激素最高(P<0.05)。结论:泌乳早期奶牛在75%放养密度条件下氧化应激水平较低,而100%放养密度导致氧化应激水平升高,同时乳腺通透性较高。因此建议泌乳早期奶牛的放养密度应该维持在较低水平,以防止氧化应激。

Effects of stocking density on oxidative stress and permeability of mammary gland in milk cow

The purpose of this study was to investigate the effects of stocking density on oxidative stress and breast permeability in early lactation cows.In this study,32 lactation cows were selected and randomly divided into two groups according to parity and milk yield.Each group had 16 cows,and each cow was regarded as 1 repeat.Cows were fed with two different feeding methods,namely 75%and 100%,for a total of 8 weeks,during which the two groups were fed the same feed.Results showed that compared with the 100%stocking density group,75%density group significantly increased the amount of lactation milk and 4%fat,energy calibration correction milk yield(P<0.05),while 75%stocking density group significantly decreased milk urea nitrogen content in the improved significantly(P<0.05),the experiments in the milk protein content(P<0.05),while 100%stocking density group significantly improved the cow milk in the number of somatic cells(P<0.05).The serum lactose content in 75%stocking density group was significantly lower than that in 100%stocking density group(P<0.05),and the serum SOD and T-AOC activity in 75%stocking density group was significantly increased compared with that in 100%stocking density group(P<0.05).Serum insulin and the ratio of insulin to glucagon were the lowest(P<0.05),but prolactin and growth hormone were the highest(P<0.05).Conclusion:in early lactation,the oxidative stress level of cows was low under 75%stocking density,but 100%stocking density led to the increase of oxidative stress level,and the permeability of mammary gland was high.Therefore,we suggest that the stocking density of early lactation cows should be maintained at a low level to prevent oxidative stress.