摘要
Beef producers are looking to alternative feed sources due to competition for starch sources among ethanol and livestock producers and with human food needs. Limited research is available on blended by-product feeds as alternative sources of starch and protein for backgrounding cattle. Three trials were conducted to evaluate the performance and effect on rumen fermentation and nutrient digestibility in growing cattle fed blended by-product pellets (BP). Pellets were based on by-products from the oilseed and grain sectors and were formulated to be isonitrogenous (17.0% CP) and isocaloric (1.92 and 1.28 Mcal kg-1 NEm and NEg, respectively). In Trial 1, four pellets were evaluated. The pellets were formulated to be either high starch (HS 45% DM basis) or high fat (HF 8.8% DM basis) and either low or high in soluble protein (LSP 27% of CP; HSP 37% of CP DM basis). In Trial 2, only the two HF pellets were evaluated. In Trial 1, 300 cross-bred steers (320 ± 21.6 kg, mean ± SD) were randomly assigned to one of 25 pens and fed one of 5 diets in a completely randomized block design. The control diet consisted of 46.9% forage and 53.1% barley-based concentrate. The four treatment diets consisted of 48.4% forage and 51.6% BP (DM basis). All diets were formulated to 1.63 and 1.02 Mcal kg-1 NEm and NEg, respectively (DM basis). In Trial 2, 180 cross-bred steers (326 ± 20.3 kg, mean ± SD) were randomly assigned to one of 15 pens with each pen randomly assigned to one of three treatments in a completely randomized design. Treatments included a control diet consisted of 54.3% forage and 45.7% barley-based concentrate and the two HF BP treatment diets which consisted of 55.6% forage and 43.4% of one of the two HF BP used in Trial 1 (DM basis). In Trial 1, no (P>0.05) effect of treatment was observed on ADG, however, DMI was reduced (P<0.01) with the HS treatment relative to the control and HF treatment. No significant differences (P=0.16) were observed in DMI between steers fed the control and HF BP diets. Gain:feed (G:F) was the poorest (P<0.01) for the HF diets. In Trial 2, ADG was lower (P=0.04) and DMI was higher (P=0.04) for HF BP (Control vs. HF), therefore cattle fed the control diet had superior feed efficiency (P<0.01). Dietary NEg content (Mcal kg-1 DM) as calculated from animal performance was 7.5 and 8.3% lower (P<0.01) for cattle fed the HF diets relative to the control cattle in Trial 1 and 2, respectively. Trial 3 used 5 crossbred heifers (631 ± 31 kg, mean ± SD) in a Latin square design. Diets were the same as that used in Trial 1. Heifers fed HF BP had higher (P=0.05) mean pH values than those fed the control diet and trended (P=0.07) to have higher mean pH than those fed the HS BP. Feeding HF BP caused a decrease (P<0.05) in propionate concentration, without affecting acetate or total VFA concentration. Rumen ammonia-N levels and digestibility of CP was highest (P<0.05) for HS, intermediate for HF, and the lowest for the control. Feeding HF BP relative to both the control and HS diets reduced (P<0.05) GE, DE and EE digestibility. Total nitrogen excretion (% of total N excretion) was not affected (P>0.05) by treatment. Feed costs per kg of gain were reduced by feeding HF BP due to cost of ingredients and relative excellent cattle performance. These results indicate that BP are a viable and economic alternative for supplementing energy and protein in backgrounding diets with no adverse effects on rumen fermentation. Moreover, feeding BP does not increase the potential of having nutrient excretion issues in the environment.
摘要译文
由于乙醇和畜牧生产商和人类食物需求，牛肉生产者正在寻求替代饲料来源。在混合的副产品饲料中提供有限的研究，作为淀粉和蛋白质的替代品，用于背景牛。进行三次试验以评估生长牛喂养副产品颗粒（BP）的生长牛中瘤胃发酵和营养消化率的性能和效果。粒料基于来自油籽和晶粒部门的副产物，配制成等异源（17.0％CP）和异蜂鸣（1.92和1.28 MCAL KG-1 NEM和Neg）。在试验1中，评估四个颗粒。将粒料配制成高淀粉（HS 45％DM基础）或高脂肪（HF 8.8％DM基础），可溶性蛋白质中的低或高（LSP 27％; HSP 37％的CP DM基础）。在试验2中，只评估两个HF颗粒。在试验1中，300个交叉繁殖带（320±21.6千克，平均值±SD）随机分配到25只笔中的一个，并以完全随机化的块设计中的5个饮食中的一个。控制饮食由46.9％的饲料和53.1％的大麦浓缩物组成。四种治疗饮食由48.4％的饲料和51.6％BP（DM基础）组成。将所有饮食均配制成1.63和1.02 MCAL KG-1 NEM和NEG（DM基础）。在试验2中，180个交叉繁殖带（326±20.3kg，平均值±SD）随机分配给15个钢笔中的一个，每支笔随机分配到完全随机设计中的三种处理中的一个。治疗剂包括对照饮食，包括54.3％的牧草和45.7％的大麦浓缩物，两种HF BP治疗饮食，其饲料55.6％，占试验中使用的两种HF BP中的一个（DM基础）中的一个。在试验1中，没有（p> 0.05）在ADG上观察到治疗的效果，然而，DMI减少（P <0.01），相对于对照和HF处理。在加入对照和HF BP饮食中的阉牛之间，在DMI中观察到没有显着差异（p = 0.16）。收益：饲料（g：f）是HF饮食中最贫穷的（p <0.01）。在试验2中，ADG较低（P = 0.04），DMI较高（P = 0.04），用于HF BP（对照与HF），因此饲喂对照饮食的牛具有优异的饲料效率（P <0.01）。从动物性能计算的饮食Neg含量（MCAL KG-1 DM）分别为7.5％和8.3％（P <0.01），饲喂HF饮食相对于试验1和2中的对照牛。试验3在拉丁方形设计中使用了5次杂交的小母牛（631±31千克，平均值±SD）。饮食与试验中使用的饮食相同。喂养HF BP的小型母牛的平均pH值比加入对照饮食和趋势（P = 0.07）具有更高的平均pH值的pH值比喂养HS BP的那些。饲料HF BP在丙酸盐浓度下导致降低（P <0.05），而不会影响乙酸盐或总VFA浓度。 HS，HF中间体的瘤胃氨-N水平和CP的消化率最高（P <0.05），以及对照的最低。相对于对照和HS饮食喂养HF BP（P <0.05）GE，DE和EE消化率。通过治疗不受氮排泄（总N排泄的百分比）（p> 0.05）。由于成分的成本和相对优异的牛绩效，通过喂养HF BP，降低了每千克收益的饲料成本。这些结果表明，BP是一种可行的和经济替代的替代品，用于补充背景中的能量和蛋白质，而不是对瘤胃发酵没有不利影响的饮食。此外，饲料BP不会增加在环境中具有营养排泄问题的可能性。
Zenobi, Marcos. COMPARISON OF STRATEGICALLY BLENDED BY-PRODUCT FEED PELLETS ON PERFORMANCE, RUMEN FERMENTATION AND NUTRIENT DIGESTIBILITY OF GROWING CATTLE[D]. CA: University of Saskatchewan, 2013