The aim of the study was to assess the effect of four energy supplements (two highly fermentable; two starch-based carbohydrates) on blood urea nitrogen (BUN), urinary urea excretion, and milk yield, in dual-purpose cows fed foliage of Leucaena leucocephala (Leucaena). Five Holstein-Zebu cows with 450 kg body weight in their second third of lactation were used in a 5 × 5 Latin square design. Cows were fed (dry basis) a mixture of 45% Leucaena and 55% Pennisetum purpureum grass. Treatments were supplementation with (i) sugarcane molasses (Mo), (ii) sorghum grain (So), (iii) fresh citrus pulp (CitP) or (iv) rice polishing (RP), all of them incorporated into the diet at 25 MJ of ME/cow/day. There was a control group (Cont) without energy supplementation. The study comprised five periods of 20 days (15 days adaptation, 5 days measurements). Dry matter intake (kg/day) was lower (P < 0.05) for Cont (9.4) compared with Mo (12.1), So (12.0), CitP (11.9) and RP (11.9) but no difference was observed among energy supplements (P > 0.05). Milk yield (kg/day) was higher (P < 0.05) in cows supplemented with starch supplements (4.7 for So; 4.9 for RP) compared with Cont (3.3). Milk yield from highly fermentable supplements (Mo and CitP) did not differ (P > 0.05) from Cont or other treatments. Milk protein, fat and lactose were not different among treatments (P > 0.05). Blood urea nitrogen and urinary urea excretion were both reduced (P < 0.05) by energy supplementation. Urinary urea excretion was not different (P > 0.05) among cows fed different sources of energy. It is concluded that in dual-purpose cows fed Leucaena foliage, supplementation with sugarcane molasses, citrus pulp or rice polishing reduced blood urea nitrogen and urinary urea excretion. Milk yield was increased by sorghum and rice polishing whereas energy supplementation did not affect milk composition.

该研究的目的是评估饲喂Leucaena叶子的两用奶牛的四种能量补充剂（两种高度可发酵；两种基于淀粉的碳水化合物）对血尿素氮（BUN），尿尿排泄和产奶量的影响。白脑（白头翁）。在5 x 5拉丁方形设计中，使用了五头荷斯坦奶牛，它们在哺乳期的第二部分体重为450公斤，体重为450公斤。给母牛喂食（干基）45％银合欢和55％狼尾草的混合物草。治疗方法是补充（i）甘蔗糖蜜（Mo），（ii）高粱谷物（So），（iii）新鲜柑橘果肉（CitP）或（iv）稻米精制（RP），所有这些都在25岁时纳入饮食ME /牛/天的MJ。有一个对照组（续），没有补充能量。该研究包括20天的五个时段（适应15天，测量5天）。 Cont（9.4）的干物质摄入量（kg / day）低于Mo（12.1），So（12.0），CitP（11.9）和RP（11.9）（P <0.05），但补充能量之间没有差异（P  > 0.05）。牛奶产量（kg /天）较高（P 与Cont（3.3）相比，补充了淀粉补充剂的母牛（So的4.7； RP的4.9）的<0.05。来自高发酵补充剂（Mo和CitP）的牛奶产量与 Cont或其他处理方法没有差异（P > 0.05）。乳蛋白，脂肪和乳糖之间无差异（P  > 0.05）。 补充能量可降低血尿素氮和尿素排泄率（P <0.05）。尿中尿素排泄率无差异（P > 0.05）喂养不同能量来源的奶牛。结论是，在饲喂Leucaena叶子的两用母牛中，补充甘蔗糖蜜，柑橘果肉或大米抛光会减少血液尿素氮和尿素排泄量。高粱和大米的抛光增加了牛奶的产量，而能量补充并没有影响牛奶的成分。