Ceconi Irene, Viano Sergio A, Méndez Daniel G, González Lucas, Davies Patricio, Elizalde Juan C, Bressan Elbio, Grandini Danilo, Nagaraja T G, Tedeschi Luis O
National Institute of Agricultural Technology (INTA), General Villegas, Buenos Aires, B6230DCB, Argentina.
Elizalde & Riffel Private Consultants, Rosario, Santa Fe, S2000ACD, Argentina.
Transl Anim Sci. 2022 Dec 1;6(4):txac154. doi: 10.1093/tas/txac154. eCollection 2022 Oct.
Monensin and virginiamycin are included in beef cattle finishing diets as prophylaxis to minimize the incidence of ruminal acidosis and liver abscesses. Due to different and probably complementary modes of action, this study aimed to determine the effects of a combination of monensin and virginiamycin, both included in the diet at recommended doses, on ruminal health, the occurrence of liver abscesses, and growth performance of feedlot-finished cattle. One hundred and forty-four steers (6 animals/pen) were fed 1 of 3 corn-based finishing diets containing 30 mg of monensin (), 25 mg of virginiamycin (), or 30 and 25 mg of monensin and virginiamycin (), respectively, per kilogram of dry matter. Ruminal pH probes were inserted into two animals per pen and set to record pH every 10 min. On d 100, animals were slaughtered, and rumens and livers were recovered, on which occurrence and degree of ruminal damage, prevalence and number of liver abscesses, and liver scores (A-: livers with no more than two small abscesses; A+: livers with at least one large abscess or more than four medium abscesses; A: any other abscessed liver) were determined. Simultaneous inclusion of monensin and virginiamycin resulted in a 4.3% decrease ( < 0.04) in dry matter intake (; 8.8, 9.2, and 9.2 ± 0.19 kg/d for MN + VM, MN, and VM-fed animals, respectively) and similar ( > 0.13) average daily body weight gain (; 1.49 ± 0.021 kg/d) and hot carcass weight (; 269 ± 1.7 kg), compared with feeding diets containing one additive or the other. Therefore, in terms of ADG, a 9.4% improvement ( < 0.01) in feed efficiency was observed in MN + VM-fed animals. Backfat thickness (5.6 ± 0.08 mm) and ribeye area (69.9 ± 0.53 cm) remained unaffected ( ≥ 0.74), as well as the minimum (4.98 ± 0.047), mean (6.11 ± 0.037), and maximum ruminal pH (7.23 ± 0.033) values and the time (125 ± 22.3 min/d), area (57.67 ± 12.383 pH × h), and episodes (22 ± 3.8 bouts) of pH below 5.6 ( ≥ 0.12). Overall, prevalence (24 ± 3.4%) and the number of liver abscesses (1.6 ± 0.14 abscesses/abscessed liver), liver scores (20 ± 3.1% of A- and 4 ± 1.8% of A livers), and prevalence (67 ± 3.5%) and degree of damage to the ruminal epithelium (2.5 ± 0.22% affected surface) were similar ( ≥ 0.18) across treatments; however, the occurrence of ruminal lesions tended ( ≤ 0.07) to be associated with that of liver abscesses and reduced ADG when feeding monensin alone.
莫能菌素和维吉尼霉素被添加到肉牛育肥日粮中作为预防措施，以尽量减少瘤胃酸中毒和肝脓肿的发生率。由于作用方式不同且可能具有互补性，本研究旨在确定按推荐剂量同时添加莫能菌素和维吉尼霉素对育肥牛瘤胃健康、肝脓肿发生情况及生长性能的影响。144头阉牛（每栏6头）分别饲喂3种以玉米为基础的育肥日粮中的一种，日粮每千克干物质分别含30毫克莫能菌素（MN）、25毫克维吉尼霉素（VM）或30毫克莫能菌素与25毫克维吉尼霉素（MN + VM）。每栏插入瘤胃pH探头至2头牛体内，并设置为每10分钟记录一次pH值。在第100天，屠宰动物，取出瘤胃和肝脏，测定瘤胃损伤的发生情况和程度、肝脓肿的发生率和数量以及肝脏评分（A -：肝脏脓肿不超过2个小脓肿；A +：肝脏有至少1个大脓肿或超过4个中脓肿；A：其他有脓肿的肝脏）。与单独添加一种添加剂的日粮相比，同时添加莫能菌素和维吉尼霉素使干物质采食量降低了4.3%（P < 0.04）（MN + VM、MN和VM组动物的干物质采食量分别为8.8、9.2和9.2±0.19千克/天），但平均日增重（P > 0.13）（1.49±0.021千克/天）和热胴体重（P > 0.13）（269±1.7千克）相似。因此，就平均日增重而言，MN + VM组动物的饲料效率提高了9.4%（P < 0.01）。背膘厚度（5.6±0.08毫米）和眼肌面积（69.9±0.53平方厘米）不受影响（P ≥ 0.74），瘤胃最低pH值（4.98±0.047）、平均pH值（6.11±0.037）和最高pH值（7.23±0.033）以及pH值低于5.6的时间（125±22.3分钟/天）、面积（57.67±12.383 pH×小时）和次数（22±3.8次）也不受影响（P ≥ 0.12）。总体而言，各处理间肝脓肿的发生率（24±3.4%）和数量（1.6±0.14个脓肿/有脓肿的肝脏）、肝脏评分（A -肝脏占20±3.1%，A肝脏占4±1.8%）以及瘤胃上皮损伤的发生率（67±3.5%）和程度（2.5±0.22%受影响面积）相似（P ≥ 0.18）；然而，单独饲喂莫能菌素时，瘤胃病变的发生与肝脓肿的发生呈趋势性相关（P ≤ 0.07），且平均日增重降低。
