Horton Lucas M, Depenbusch Brandon E, Dewsbury Diana M, McAtee Taylor B, Betts Nick B, Renter David G
The Center for Outcomes Research and Epidemiology, Department of Diagnostic Medicine and Pathobiology, Kansas State University College of Veterinary Medicine, Manhattan, KS 66506, USA.
Innovative Livestock Services, Inc., Great Bend, KS 67530, USA.
Vet Sci. 2023 Jan 17;10(2):67. doi: 10.3390/vetsci10020067.
The objectives were to evaluate the effects of metaphylaxis (META) and pull-and-treat (PT) programs on health, antimicrobial use, beef production, economics, and greenhouse gas emissions in cattle at medium risk for bovine respiratory disease (BRD). A randomized complete block design was used at two US commercial feedlots. Steers and heifers [2366 total; 261 (±11.0) kg initial weight] were blocked by sex and feedlot arrival, and allocated to one of two pens within a block (16 pens total, eight blocks). Pens were randomly assigned to treatment: META, tulathromycin injection at initial processing; or PT, tulathromycin injection only for first clinical BRD treatment. Data were analyzed with linear and generalized linear mixed models. There was greater BRD morbidity in PT than META cattle (17.2% vs. 7.3% respectively; < 0.01), and greater total mortality (2.5% vs. 1.1% respectively; = 0.03). Per animal enrolled, 1.1 antimicrobial doses were used for META compared to 0.2 for PT ( < 0.01). Per animal enrolled, final live ( = 0.04) and carcass ( = 0.08) weights were greater for META than PT; however, net returns ($/animal) were not significantly different ( = 0.71). Compared to PT, total lifetime estimated CO equivalent emissions from production were reduced by 2% per unit of live weight for META ( = 0.09). While antimicrobial use was reduced with PT, there may be substantial negative impacts on other outcomes if META was not used in this type of cattle population.
目的是评估群体预防（META）和发现即治疗（PT）方案对患牛呼吸道疾病（BRD）中度风险牛的健康、抗菌药物使用、牛肉生产、经济效益和温室气体排放的影响。在美国的两个商业饲养场采用了随机完全区组设计。阉牛和小母牛[共2366头；初始体重261（±11.0）千克]按性别和进入饲养场的时间进行分组，并分配到一个区组内的两个围栏之一（共16个围栏，8个区组）。围栏被随机分配到以下处理：META，在初次处理时注射土拉霉素；或PT，仅在首次临床BRD治疗时注射土拉霉素。数据采用线性和广义线性混合模型进行分析。PT组的BRD发病率高于META组（分别为17.2%和7.3%；P<0.01），总死亡率也更高（分别为2.5%和1.1%；P = 0.03）。每头入组动物，META使用1.1剂抗菌药物，而PT使用0.2剂（P<0.01）。每头入组动物，META的最终活重（P = 0.04）和胴体重（P = 0.08）均高于PT；然而，净收益（美元/头）无显著差异（P = 0.71）。与PT相比，META每单位活重的生产过程中估计的总终身二氧化碳当量排放量降低了2%（P = 0.09）。虽然PT减少了抗菌药物的使用，但如果在这类牛群中不使用META，可能会对其他结果产生重大负面影响。
