Arkfeld E K, Carr S N, Rincker P J, Gruber S L, Allee G L, Dilger A C, Boler D D
J Anim Sci. 2015 Oct;93(10):5028-35. doi: 10.2527/jas.2015-9314.
The objective was to evaluate the effect of feeding narasin (Skycis; Elanco Animal Health, Greenfield, IN) on growth performance and carcass characteristics of finishing pigs sold in a 3-phase marketing system. Pigs ( = 1,232) were housed in 56 single-sex pens (22 pigs/pen) divided into 2 even blocks based on initiation of treatment. Each treatment × sex combination was replicated 14 times. Pigs were fed either 0 mg/kg narasin (control) or 15 mg/kg narasin for up to 85 d of finishing (initiated at an average of 52.95 kg BW). In each pen, 18% (4 pigs per pen) of pigs were sold in the first marketing group (Day 64 of dietary treatment), 50% (11 of the original 22) were sold in the second marketing group (Day 78), and 32% (the remaining 7 pigs) were sold in the third marketing group (Day 85). Data were analyzed as a randomized complete block design with pen as the experimental unit. The model included the fixed effects of diet, sex, and their interaction. Block and replicate nested within block were random variables. Carcass data from pigs in marketing group 3 of block 2 was not collected due to inclement weather. Narasin had no effect on growth performance traits ( ≥ 0.15) in phases 1 (Days 1-28) or 2 (Days 29-56), regardless of sex. Barrows fed narasin had a 2.0% greater overall (Day 0-85) ADG than barrows fed the control diet ( < 0.01), but ADG of gilts was not different due to diet ( = 0.69). Regardless of sex, narasin improved ( = 0.03) feed efficiency (G:F) by 1.3% throughout the 85-d feeding period. There were no effects ( ≥ 0.21) of narasin on carcass composition in marketing groups 1 and 2. Narasin-fed barrows in marketing group 3 had 0.9 percentage units lower ( < 0.01) estimated carcass lean compared with barrows fed control diets (51.0 vs. 52.0%); no difference existed in gilts ( = 0.21). This is likely due to narasin-fed barrows of marketing group 3 tending ( = 0.06) to have 7.7% greater fat depth than control barrows of marketing group 3. Pooled effects (across all 3 marketing groups) of feeding narasin tended ( = 0.08) to reduce loin depth by 1.1% (60.00 vs. 60.66 mm), but there were no effects on fat depth ( = 0.24) or estimated carcass lean ( = 0.11). Overall, narasin can be used during the last 85 d of feeding to increase feed efficiency of barrows and gilts with minimal impact on carcass composition.
本研究旨在评估在三阶段销售体系中，饲喂那拉菌素（速百治；美国礼来动物保健公司，格林菲尔德，印第安纳州）对育肥猪生长性能和胴体特性的影响。试验猪（(n = 1232)头）饲养在56个单性别猪栏中（每栏22头猪），根据处理起始时间分为2个均衡区组。每个处理×性别组合重复14次。猪只在育肥期（平均体重52.95 kg开始）最多85天的时间内，分别饲喂0 mg/kg那拉菌素（对照）或15 mg/kg那拉菌素。每个猪栏中，18%（每栏4头猪）的猪只在第一个销售组（日粮处理第64天）出售，50%（最初22头中的11头）在第二个销售组（第78天）出售，32%（其余7头猪）在第三个销售组（第85天）出售。数据采用以猪栏为实验单位的随机完全区组设计进行分析。模型包括日粮、性别及其交互作用的固定效应。区组以及区组内的重复为随机变量。由于恶劣天气，未收集第2区组第3销售组猪只的胴体数据。那拉菌素对第1阶段（第1 - 28天）或第2阶段（第29 - 56天）的生长性能指标无影响（(P≥0.15)），无论性别如何。饲喂那拉菌素的阉公猪在整个育肥期（第0 - 85天）的平均日增重比饲喂对照日粮的阉公猪高2.0%（(P < 0.01)），但日粮对小母猪平均日增重无影响（(P = 0.69)）。无论性别如何，那拉菌素在整个85天的饲喂期内提高了（(P = 0.03)）饲料效率（料肉比）1.3%。那拉菌素对第1和第2销售组的胴体组成无影响（(P≥0.21)）。与饲喂对照日粮的阉公猪相比，第3销售组中饲喂那拉菌素的阉公猪估计胴体瘦肉率低0.9个百分点（(P < 0.01)）（分别为51.0%和52.0%）；小母猪之间无差异（(P = 0.21)）。这可能是因为第3销售组中饲喂那拉菌素的阉公猪的脂肪厚度比第3销售组中饲喂对照日粮的阉公猪厚7.7%（(P = 0.06)）。饲喂那拉菌素的综合效应（涵盖所有3个销售组）倾向于（(P = 0.08)）使腰椎深度降低1.1%（分别为60.66 mm和60.00 mm），但对脂肪厚度（(P = 0.24)）或估计胴体瘦肉率无影响（(P = 0.11)）。总体而言，那拉菌素可在育肥期的最后85天使用，以提高阉公猪和小母猪的饲料效率，同时对胴体组成影响最小。
