Bauer M L, Schimek D E, Reed J J, Caton J S, Berg P T, Lardy G P
Department of Animal and Range Sciences, North Dakota State University, Fargo 58105, USA.
J Anim Sci. 2007 Sep;85(9):2290-7. doi: 10.2527/jas.2006-652. Epub 2007 May 15.
The objectives of this experiment were to determine a NE value for pressed beet pulp and the value of concentrated separator by-product (de-sugared molasses) as a ruminal N source in growing and finishing diets for beef cattle. One hundred forty-four cross-bred beef steers (282 +/- 23 kg of initial BW) were used in 2 experiments (growing and finishing). A randomized complete block design was used, with a 3 x 2 factorial arrangement of treatments (level of pressed beet pulp and inclusion of concentrated separator by-product) for both studies. Steers were blocked by BW and allotted randomly to 1 of 6 treatments. In the growing study, the control diet contained 49.5% corn, 31.5% corn silage, 10.0% alfalfa hay, and 9.0% supplement (DM basis). Pressed beet pulp replaced corn at 0, 20, or 40% of dietary DM, and concentrated separator by-product replaced corn and urea at 10% of dietary DM. The growing study lasted for 84 d. Initial BW was an average of 2-d BW after a 3-d, restricted (1.75% of BW) feeding of 50% alfalfa hay and 50% corn silage (DM basis), and final BW was an average of 2-d BW after a 3-d, restricted (1.75% of BW) feeding of 31.5% corn silage, 10.0% alfalfa hay, 25.0% dry-rolled corn, 20.0% pressed beet pulp, 5.0% concentrated separator by-product, and 8.5% supplement (DM basis). After the growing study, the steers were weighed (415 +/- 32 kg), rerandomized, and allotted to 1 of 6 finishing diets. The control diet for the finishing study included 45% dry-rolled corn, 40% high-moisture corn, 5% brome hay, 5% pressed beet pulp, and 5% supplement. Pressed beet pulp replaced high-moisture corn at 5.0, 12.5, and 20.0% of the dietary DM, and concentrated separator by-product replaced high-moisture corn and supplement at 10.0% of diet DM. Steers were slaughtered on d 83 or 98 of the study. In the growing study, the addition of pressed beet pulp to growing diets linearly decreased (P = 0.001) DMI and ADG and inclusion of 10% concentrated separator by-product decreased (P = 0.001) G:F. Increased levels of pressed beet pulp in the finishing diets caused a linear decrease (P = 0.001) in ADG and tended (P = 0.06 and 0.07 for kg/d and % of BW, respectively) to quadratically decrease DMI, whereas addition of concentrated separator by-product increased (P = 0.02 and 0.001 for kg/d and % of BW, respectively) DMI. Apparent NEg of pressed beet pulp was 94.2% of that of corn in the growing study and 81.5% of that of corn in the finishing study.
本试验的目的是确定压榨甜菜粕的净能值以及浓缩分离器副产品（脱糖糖蜜）作为肉牛生长育肥日粮瘤胃氮源的价值。144头杂交肉牛（初始体重282±23千克）用于两项试验（生长和育肥）。两项研究均采用随机完全区组设计，处理采用3×2析因排列（压榨甜菜粕水平和浓缩分离器副产品的添加）。肉牛按体重进行分块，并随机分配到6种处理中的一种。在生长试验中，对照日粮含有49.5%的玉米、31.5%的玉米青贮、10.0%的苜蓿干草和9.0%的补充料（干物质基础）。压榨甜菜粕以日粮干物质的0%、20%或40%替代玉米，浓缩分离器副产品以日粮干物质的10%替代玉米和尿素。生长试验持续84天。初始体重是在按体重的1.75%限制饲喂50%苜蓿干草和50%玉米青贮（干物质基础）3天后连续2天体重的平均值，最终体重是在按体重的1.75%限制饲喂31.5%玉米青贮、10.0%苜蓿干草、25.0%干碾压玉米、20.0%压榨甜菜粕、5.0%浓缩分离器副产品和8.5%补充料（干物质基础）3天后连续2天体重的平均值。生长试验结束后，对肉牛称重（415±32千克），重新随机分组，并分配到6种育肥日粮中的一种。育肥试验的对照日粮包括45%干碾压玉米、40%高水分玉米、5%雀麦干草、5%压榨甜菜粕和5%补充料。压榨甜菜粕以日粮干物质的5.0%、12.5%和20.0%替代高水分玉米，浓缩分离器副产品以日粮干物质的10.0%替代高水分玉米和补充料。在试验的第83天或98天对肉牛进行屠宰。在生长试验中，在生长日粮中添加压榨甜菜粕使干物质采食量（DMI）和平均日增重（ADG）呈线性下降（P = 0.001），添加10%浓缩分离器副产品使料重比（G:F）下降（P = 0.001）。育肥日粮中压榨甜菜粕水平的提高使ADG呈线性下降（P = 0.001），并使DMI有二次下降的趋势（分别以千克/天和体重百分比计，P = 0.06和0.07），而添加浓缩分离器副产品使DMI增加（分别以千克/天和体重百分比计，P = 0.02和0.001）。在生长试验中，压榨甜菜粕的表观净能（NEg）为玉米的94.2%，在育肥试验中为玉米的81.5%。
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