Abstract

The aim of this study was to investigate the variation of gross composition, somatic cell count, urea content, and fatty acids (FA) composition of bulk milk from single-breed and multi-breed farms in alpine area, keeping either Brown Swiss (BS), Holstein Friesian (HF), Simmental (SI), or their combinations. Gross milk composition, urea content, and FA composition were predicted using mid-infrared spectroscopy. Observations were grouped in 7 combinations consisting of 3 singlebreed and 4 multi-breed types of herd. A mixed linear model was used for data analysis, accounting for the fixed effects of herd composition (7 combinations), month of sampling, year of sampling, and the interactions between herd composition and month of sampling, and between herd composition and year of sampling. Farm was included as random effect. Results highlighted that about two thirds of South Tyrolean farms were single-breed and herds with more than 20 lactating cows changed herd structure over time, switching from multi- to single-breed. Single-breed BS farms produced milk with greater fat, protein, casein, lactose, and FA content than single-breed HF and SI farms. Further, multi-breed herds including BS cows produced milk with greater fat, protein, casein, and polyunsaturated FA content than multi-breed HF+SI herds. Overall, single-breed SI farms produced milk with lower somatic cell count than other herd combinations. Despite the number of BS cows in South Tyrol has decreased in favor of SI in the last years, this breed is still the most interesting for alpine dairy farming to achieve optimal milk quality in both single- and multi-breed scenarios. The tendency to move to SI is mainly related to good milk performance of SI cows coupled with their robustness, high carcass value, high market value of calves, and adaptability to mountain farming system.

中文翻译：

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山区牛群组成对散装奶品质的影响

抽象的

这项研究的目的是调查高山地区单品种和多品种农场散装奶的总成分，体细胞计数，尿素含量和脂肪酸（FA）组成的变化，并保持棕色瑞士（BS ），荷斯坦·弗里斯兰（HF），西门塔尔（SI）或它们的组合。使用中红外光谱可以预测牛奶的总成分，尿素含量和FA成分。将观察结果分为7种组合，其中包括3种单犬种和4种多犬种类型的牛群。使用混合线性模型进行数据分析，考虑了羊群组成（7种组合），采样月份，采样年份以及羊群组成与采样月份之间，以及羊群组成与采样年份之间的相互作用的固定影响。 。农场作为随机效应包括在内。结果表明，南蒂罗尔州大约三分之二的农场是单犬种，有超过20头泌乳母牛的牛群随着时间的推移改变了牛群的结构，从多品种改为单品种。单品种BS农场生产的牛奶中脂肪，蛋白质，酪蛋白，乳糖和FA含量高于单品种HF和SI农场。此外，包括BS奶牛在内的多品种牛群所生产的牛奶具有比多品种HF + SI牛群更高的脂肪，蛋白质，酪蛋白和多不饱和FA含量。总体而言，单品种SI农场生产的牛奶的体细胞数低于其他牧群组合。尽管最近几年南蒂罗尔的BS奶牛数量有所减少，转而支持SI，但这种品种仍然是高山奶牛场最感兴趣的，能够在单品种和多品种情况下实现最佳牛奶质量。