Dos Santos Neto J M, Worden L C, Boerman J P, Bradley C M, Lock A L
Department of Animal Science, Michigan State University, East Lansing, MI 48824.
JDS Commun. 2024 Dec 16;6(2):206-211. doi: 10.3168/jdsc.2024-0627. eCollection 2025 Mar.
Our objective was to compare abomasal infusions of linoleic (18:2n-6) and α-linolenic (18:3n-3) acid on the incorporation of n-6 and n-3 fatty acids (FA) into the milk fat of dairy cows and to evaluate their potential carryover effects. Six rumen-cannulated multiparous Holstein cows (252 ± 33 DIM) were fed the same diet and assigned to 1 of 2 treatments in a completely randomized design with repeated measures. Treatments were abomasal infusions (67 g/d total FA) of (1) n-6 FA blend (N6) to provide ∼43 g/d 18:2n-6 and 8 g/d of 18:3n-3; or (2) n-3 FA blend (N3) providing 43 g/d 18:3n-3 and 8 g/d 18:2n-6. The treatment period lasted from d 1 to 20, and the carryover period lasted from d 21 to 36. Compared with N6, the N3 treatment increased the yields of total n-3 FA, 18:3n-3, and eicosapentaenoic acid (20:5n-3) from d 4 to 20, decreased total n-6 FA from d 8 to 20 and 18:2n-6 from d 8 to 16, and tended to decrease arachidonic acid (20:4n-6) from d 12 to 16. During the treatment period, n-3 FA transfer efficiency to milk for N3 was 47%, whereas n-6 FA transfer efficiency to milk for N6 was 39%. A similar pattern was observed for milk FA content, with N3 increasing the contents of total n-3 FA, 18:3n-3, and 20:5n-3 from d 4 to 20; and decreasing total n-6 FA from d 4 to 20, 18:2n-6 from d 4 to 16, and 20:4n-6 from d 12 to 16 compared with N6. We only observed positive carryover effects for N3, with the treatment increasing or tending to increase the yield of n-3 FA until d 28 and increasing the content of total n-3 FA until d 26. We observed no carryover effects for N6. In addition, we did not detect 22:6n-3 either during the treatment or carryover periods. In conclusion, abomasally infusing N3 and N6 for 20 d increased the yields and contents of n-3 and n-6 FA in milk fat, respectively. Interestingly, the increases were more pronounced in n-3 than in n-6 milk FA, with a transfer efficiency of 47% and 39% during the treatment period, respectively. Furthermore, a positive carryover effect was observed only for n-3 FA.
我们的目标是比较向皱胃输注亚油酸（18:2n - 6）和α - 亚麻酸（18:3n - 3）对奶牛乳脂中n - 6和n - 3脂肪酸（FA）掺入情况的影响，并评估它们潜在的残留效应。选用6头装有瘤胃瘘管的经产荷斯坦奶牛（产犊后252 ± 33天），给它们饲喂相同的日粮，并采用完全随机设计和重复测量的方法将其分配到2种处理中的1种。处理方式为向皱胃输注（总FA 67克/天）：（1）n - 6 FA混合物（N6），提供约43克/天的18:2n - 6和8克/天的18:3n - 3；或（2）n - 3 FA混合物（N3），提供43克/天的18:3n - 3和8克/天的18:2n - 6。处理期从第1天持续到第20天，残留期从第21天持续到第36天。与N6相比，N3处理从第4天到第20天提高了总n - 3 FA、18:3n - 3和二十碳五烯酸（20:5n - 3）的产量，从第8天到第20天降低了总n - 6 FA，从第8天到第16天降低了18:2n - 6，并且从第12天到第16天有降低花生四烯酸（20:4n - 6）的趋势。在处理期内，N3的n - 3 FA向牛奶中的转移效率为47%，而N6的n - 6 FA向牛奶中的转移效率为39%。在乳脂FA含量方面也观察到类似模式，与N6相比，N3从第4天到第20天提高了总n - 3 FA、18:3n - 3和20:5n - 3的含量；从第4天到第20天降低了总n - 6 FA，从第4天到第16天降低了18:2n - 6，从第12天到第16天降低了20:4n - 6。我们仅观察到N3有正向残留效应，该处理使n - 3 FA产量在第28天前一直增加或有增加趋势，使总n - 3 FA含量在第26天前一直增加。我们未观察到N6有残留效应。此外，在处理期或残留期内均未检测到22:6n - 3。总之，向皱胃输注N3和N6 20天分别提高了乳脂中n - 3和n - 6 FA的产量和含量。有趣的是，n - 3 FA的增加比n - 6 FA更明显，处理期内转移效率分别为47%和39%。此外，仅观察到n - 3 FA有正向残留效应。
