This study investigated the effect of, and interactions between, US Brown Swiss (BS) genetics and season on milk yield, basic composition and fatty acid profiles, from cows on low-input farms in Switzerland. Milk samples (n = 1,976) were collected from 1,220 crossbreed cows with differing proportions of BS, Braunvieh and Original Braunvieh genetics on 40 farms during winter-housing and summer-grazing. Cows with more BS genetics produced more milk in winter but not in summer, possibly because of underfeeding potentially high-yielding cows on low-input pasture-based diets. Cows with more Original Braunvieh genetics produced milk with more (i) nutritionally desirable eicosapentaenoic and docosapentaenoic acids, throughout the year, and (ii) vaccenic and α-linolenic acids, total omega-3 fatty acid concentrations and a higher omega-3/omega-6 ratio only during summer-grazing. This suggests that overall milk quality could be improved by re-focussing breeding strategies on cows’ ability to respond to local dietary environments and seasonal dietary changes.

这项研究调查了美国布朗瑞士（BS）遗传学和季节对瑞士低投入农场奶牛的牛奶产量，基本成分和脂肪酸谱的影响以及它们之间的相互作用。在40个农场的冬季饲养和夏季放牧期间，从1,220头不同比例的BS，Braunvieh和原始Braunvieh遗传学的杂种母牛中收集了牛奶样本（n = 1,976）。具有BS遗传基因的奶牛在冬季而不是夏季生产更多的牛奶，这可能是因为低投入的牧场饲喂低产高产奶牛的缘故。拥有Braunvieh原始遗传学特征的奶牛全年生产的牛奶含（i）营养上理想的二十碳五烯酸和二十二碳五烯酸，以及（ii）痘苗酸和α-亚麻酸，仅在夏季放牧期间，总的omega-3脂肪酸浓度和较高的omega-3 / omega-6比值。这表明，通过将育种策略重新集中于母牛对当地饮食环境和季节性饮食变化的反应能力，可以改善整体牛奶质量。