Smock Taylor M, Samuelson Kendall L, Hergenreder Jerilyn E, Rounds P Whitney, Richeson John T
Department of Agricultural Sciences, West Texas A&M University, Canyon, TX.
Animal Nutrition and Health, Kemin Industries, Inc., Des Moines, IA.
Transl Anim Sci. 2020 Sep 3;4(3):txaa163. doi: 10.1093/tas/txaa163. eCollection 2020 Jul.
The study objective was to determine the effects of PB6 and/or chromium propionate supplementation on health, growth performance, and carcass characteristics of high-risk beef cattle during a 56-d feedlot receiving period and the subsequent finishing period. Four truckload blocks of crossbred beef bulls ( = 300) and steers [ = 84; body weight (BW) = 220 ± 16.2 kg] were sourced from regional auction markets and assigned randomly to treatments arranged in a 2 × 2 factorial. The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) placebo control (CON); 2) 13 g per animal daily of PB6 (CST); 3) 450 ppb dry matter (DM) chromium propionate (CHR); and 4) 13 g per animal daily of PB6 and 450 ppb DM chromium propionate (CST + CHR). Treatments were top dressed in feed bunks daily using 0.45 kg per animal ground corn carrier immediately following feed delivery. Data were analyzed using mixed models. During the receiving period, dry matter intake (DMI) increased ( ≤ 0.03) for CST during each interim period. Overall receiving period daily DMI was 0.35 kg per animal greater for CST ( = 0.01). Cattle fed CST had greater ( ≤ 0.06) BW on days 14, 28, and 56. Likewise, average daily gain (ADG) was improved for CST from day 0 to 14 ( = 0.04) and for the overall receiving period (days 0-56; = 0.04). From days 0 to 14, CST tended ( 0.08) to increase gain:feed. During the finishing period, CHR reduced ( = 0.02) final BW and ADG (day 56 to final; = 0.01) and ADG was less for CHR over the entire feeding period (day 0 to final; = 0.03). The main effect of both CST ( = 0.02) and CHR ( = 0.03) decreased the overall treatment rate for bovine respiratory disease (BRD), and CST reduced overall antimicrobial treatment cost by $3.50 per animal compared to CON ( 0.03). Hot carcass weight (HCW) decreased ( = 0.01) in cattle fed CHR. The percentage of edible livers tended to increase (CST × CHR; = 0.08) in the CST treatment. Feed intake and growth performance outcomes during the receiving period were improved by CST but not CHR supplementation. However, both CST and CHR supplementation decreased the BRD morbidity rate. During the finishing period, performance and HCW were reduced in cattle supplemented with CHR.
本研究的目的是确定在56天的育肥期及随后的育肥后期，补充PB6和/或丙酸铬对高危肉牛健康、生长性能和胴体特性的影响。从区域拍卖市场采购了4车杂交肉牛公牛（n = 300）和阉牛[n = 84；体重（BW）= 220±16.2千克]，并随机分配到按2×2析因设计安排的处理组中。广义完全区组设计包括每个处理12个栏舍重复，以栏舍作为实验单位。处理组分别为：1）安慰剂对照（CON）；2）每头动物每天13克PB6（CST）；3）450 ppb干物质（DM）丙酸铬（CHR）；4）每头动物每天13克PB6和450 ppb DM丙酸铬（CST + CHR）。每天在饲料槽中进行顶饲，饲料投喂后立即使用每头动物0.45千克的粉碎玉米作为载体。使用混合模型分析数据。在育肥期，CST在每个中期阶段干物质摄入量（DMI）增加（P≤0.03）。整个育肥期的每日DMI，CST组每头动物比CON组多0.35千克（P = 0.01）。在第14、28和56天，饲喂CST的牛体重更大（P≤0.06）。同样，从第0天到第14天，CST组的平均日增重（ADG）有所改善（P = 0.04），整个育肥期（第0 - 56天；P = 0.04）也是如此。从第0天到第14天，CST组的增重：饲料比有增加趋势（P = 0.08）。在育肥后期，CHR降低了最终体重（P = 0.02）和ADG（第56天至结束；P = 0.01），并且在整个饲养期（第0天至结束；P = 0.03）CHR组的ADG更低。CST（P = 0.02）和CHR（P = 0.03）的主要作用均降低了牛呼吸道疾病（BRD）的总体发病率，并且与CON组相比，CST组每头动物的总体抗菌治疗成本降低了3.50美元（P = 0.03）。饲喂CHR的牛热胴体重（HCW）降低（P = 0.01）。在CST处理组中，可食用肝脏的比例有增加趋势（CST×CHR；P = 0.08）。在育肥期，补充CST可改善采食量和生长性能指标，但补充CHR则无此效果。然而，补充CST和CHR均降低了BRD发病率。在育肥后期，补充CHR的牛的性能和HCW降低。
