Animal Nutrition Group, Wageningen University, Marijkeweg 40, 6709 PG Wageningen, the Netherlands.
J Dairy Sci. 2011 Dec;94(12):6078-91. doi: 10.3168/jds.2011-4617.
The effects of an increasing proportion of crushed linseed (CL) in combination with varying forage type (grass or corn silage) and forage to concentrate ratio (F:C), and their interactions on milk fatty acid (FA) profile of high-producing dairy cows was studied using a 3-factor Box-Behnken design. Sixteen Holstein and 20 Swedish Red cows were blocked according to breed, parity, and milk yield, and randomly assigned to 4 groups. Groups were fed different treatment diets formulated from combinations of the 3 main factors each containing 3 levels. Forage type (fraction of total forage dry matter, DM) included 20, 50, and 80% grass silage, with the remainder being corn silage. The F:C (DM basis) were 35:65, 50:50, and 65:35, and CL was supplied at 1, 3, and 5% of diet DM. Starch and neutral detergent fiber content (DM basis) of the treatment diets ranged from 117 to 209 g/kg and 311 to 388 g/kg, respectively. Thirteen treatment diets were formulated according to the Box-Behnken design. During 4 experimental periods of 21 d each, all treatment diets were fed, including a repetition of the center point treatment (50% grass silage, 50:50F:C, 3% CL) during every period. Intake, production performance, and milk FA profile were measured, and response surface equations were derived for these variables. Shifting from 80% grass silage to 80% corn silage in the diet linearly increased dry matter intake (DMI), net energy for lactation (NE(L)) intake, cis-9,cis-12-C18:2 (C18:2n-6) intake, and milk yield, and linearly decreased cis-9,cis-12,cis-15-C18:3 (C18:3n-3) intake and milk fat content. Shifting from a high forage to a high concentrate diet linearly increased DMI, NE(L) intake, C18:2n-6 intake, and milk yield, and decreased milk fat content. Supplementation of CL linearly increased C18:3n-3 intake, but had no effect on DMI, NE(L) intake, milk yield, or milk fat content. Shifting from 80% grass silage to 80% corn silage linearly increased proportions of trans-10-C18:1 and C18:2n-6 in milk fat, whereas the proportions of trans-11,cis-15-C18:2 and C18:3n-3 linearly decreased. Significant interactions between CL supplementation and F:C were found for proportions of trans-10-C18:1, trans-15-C18:1, cis-15-C18:1, trans-11,cis-15-C18:2, and C18:3n-3 in milk fat, with the highest levels achieved when the diet contained 5% CL and a 35:65F:C ratio. The effect of supplementing CL on several milk FA proportions, including C18:2n-6 and C18:3n-3, depends significantly on the F:C ratio and forage type in the basal diet.
采用三因子 Box-Behnken 设计研究了随着亚麻籽压片（CL）比例的增加（结合不同的饲草料类型（干草或青贮玉米）和饲草料与精料比例（F:C））及其互作对高产奶牛乳脂肪酸（FA）谱的影响。根据品种、胎次和产奶量将 16 头荷斯坦奶牛和 20 头瑞典红牛分成 16 个组，并随机分配到 4 个组。各组分别饲喂由 3 个主要因素组合而成的不同处理日粮，每个因素有 3 个水平。饲草料类型（总饲草料干物质的比例，DM）包括 20%、50%和 80%的青贮玉米，其余为青贮玉米。F:C（DM 基础）为 35:65、50:50 和 65:35，CL 分别占日粮 DM 的 1%、3%和 5%。处理日粮的淀粉和中性洗涤纤维含量（DM 基础）分别为 117-209 g/kg 和 311-388 g/kg。根据 Box-Behnken 设计共配制了 13 种处理日粮。在每个 21d 的 4 个试验期内，饲喂了所有处理日粮，包括每个时期重复中心处理（50%青贮玉米、50:50F:C、3%CL）。测定了采食量、生产性能和乳 FA 谱，并为这些变量推导出响应面方程。饲粮中 80%青贮玉米转变为 80%青贮玉米，干物质采食量（DMI）、泌乳净能（NE(L)）采食量、顺式-9，顺式-12-十八碳二烯酸（C18:2n-6）采食量和产奶量线性增加，而顺式-9，顺式-12，顺式-15-十八碳三烯酸（C18:3n-3）采食量和乳脂含量线性下降。高饲草料向高精料饲粮的转变线性增加了 DMI、NE(L)采食量、C18:2n-6 采食量和产奶量，降低了乳脂含量。CL 补充线性增加了 C18:3n-3 的摄入量，但对 DMI、NE(L)采食量、产奶量或乳脂含量没有影响。饲粮中 80%青贮玉米转变为 80%青贮玉米，乳脂中反式-10-十八碳-1 酸和 C18:2n-6 的比例线性增加，而反式-11，顺式-15-十八碳-2 酸和 C18:3n-3 的比例线性降低。CL 补充与 F:C 之间存在显著的互作，对乳脂中反式-10-十八碳-1 酸、反式-15-十八碳-1 酸、顺式-15-十八碳-1 酸、顺式-11，顺式-15-十八碳-2 酸和 C18:3n-3 的比例有显著影响，当饲粮中含有 5%CL 和 35:65F:C 比例时，这些脂肪酸的比例最高。CL 对 C18:2n-6 和 C18:3n-3 等几种乳 FA 比例的补充作用，显著依赖于基础饲粮中的 F:C 比例和饲草料类型。
