Kostovska Renata, Horan Brendan, Drouin Gaetan, Tobin John T, O'Callaghan Tom F, Kelly Alan L, Gómez-Mascaraque Laura G
Food Chemistry and Technology Department, Teagasc, Fermoy, Co. Cork, Ireland P61 C996; School of Food and Nutritional Sciences, University College Cork, Co. Cork, Ireland T12 Y337; VistaMilk SFI Research Centre, Teagasc, Fermoy, Co. Cork, Ireland P61 C996.
Animal and Grassland Research and Innovation Centre, Teagasc, Fermoy, Co. Cork, Ireland P61 C996.
J Dairy Sci. 2024 Dec;107(12):10256-10267. doi: 10.3168/jds.2024-24975. Epub 2024 Jul 14.
In recent years, significant emphasis has been placed on the composition of pasture-based cow feed and the potential benefits of incorporating multispecies swards to improve sustainability and biodiversity. This study compared the effects of a conventional perennial ryegrass (PRG) monoculture supported by high-chemical N usage with a low-chemical-N application multispecies sward system (MSS) on the composition and quality of milk across lactation using spring-calving Holstein-Friesian (HF) and Jersey Holstein-Friesian (JFX) cows. Bulk milk samples (n = 144) were collected from each group at morning and evening milking on a weekly basis (n = 36) throughout lactation and analyzed for gross composition and physicochemical properties. Cow breed had a significant effect on milk profile, with milk from HF cows having significantly smaller milk fat globule (MFG) size, higher instability index values, higher yield, and lower total solids levels, compared with JFX cows. Notably, HF cows had increased milk total solids and fat levels when fed on MSS, as opposed to the PRG-fed HF cows. Feeding MSS pasture increased creaming velocity values in mid and late lactation, and resulted in similar milk gross composition to PRG. In comparison to PRG, MSS-fed groups showed significantly increased total solids yield, including higher levels of protein and fat yield. In late lactation, MSS feeding was associated with reduced MFG size. All physicochemical properties studied (MFG size, creaming velocity, instability index) showed decreasing values from early to late lactation stages. Overall, these findings demonstrate the significant effects of cow diet, breed, and stage of lactation on compositional and physicochemical characteristics of milk, with important implications for milk processing and dairy product quality.
近年来，人们十分重视以牧场为基础的奶牛饲料组成以及采用多物种草皮来提高可持续性和生物多样性的潜在益处。本研究比较了高化学氮肥用量支持的传统多年生黑麦草（PRG）单一栽培与低化学氮肥施用量的多物种草皮系统（MSS）对春季产犊的荷斯坦-弗里生（HF）奶牛和泽西荷斯坦-弗里生（JFX）奶牛整个泌乳期牛奶成分和质量的影响。在整个泌乳期，每周早晚挤奶时从每组采集大量牛奶样本（n = 144）（n = 36），并分析其总体成分和理化性质。奶牛品种对牛奶特征有显著影响，与JFX奶牛相比，HF奶牛的乳脂肪球（MFG）尺寸明显更小，不稳定指数值更高，产量更高，总固体水平更低。值得注意的是，与饲喂PRG的HF奶牛相比，饲喂MSS的HF奶牛的牛奶总固体和脂肪水平有所提高。饲喂MSS牧场可提高泌乳中期和后期的乳脂上浮速度值，并使牛奶总体成分与PRG相似。与PRG相比，饲喂MSS的组总固体产量显著增加，包括蛋白质和脂肪产量更高。在泌乳后期，饲喂MSS与MFG尺寸减小有关。所研究的所有理化性质（MFG尺寸、乳脂上浮速度、不稳定指数）从泌乳早期到后期均呈现下降值。总体而言，这些发现证明了奶牛饮食、品种和泌乳阶段对牛奶成分和理化特性的显著影响，对牛奶加工和乳制品质量具有重要意义。
