该实验比较了narasin和莫能菌素作为自然感染艾美球虫的小牛的抗球虫药。二十四个断奶,将未cast割的雄性小牛(Bosindicus×B.taurus杂交)分配到该实验中(第-8至42天)。所有小牛均被艾美球虫感染。根据在第-8天和第-7天收集的粪便样本的每克卵囊计数(OPG)(平均1,059±101卵囊/g)。小牛被安置在单独的围栏中,收到玉米青贮,矿物混合物,和随意饮用的水,除了每天200克/头的谷物补充剂。在第-2天和-1天收集粪便样本用于OPG,并将结果平均为初始OPG值。根据最初的OPG,小牛被封闭成八个小牛,每个小牛三只,根据第-1天记录的体重(BW)在每个区块内排名,并分配接受narasin(NAR;0.8mg/kgBW),莫能菌素(MON;1mg/kgBW),或无离子载体(CON;阴性对照)。离子载体被添加到谷物补充剂中,并从实验的第0天到第42天提供。在第7、14、21、28、35和42天记录小牛BW。在第6天和第7天、第13天和第14天、第20天和第21天、第26天和第27天、第34天和第35天以及第41天和第42天收集粪便样品用于OPG分析,对连续几天收集的样品的结果进行平均。也将来自相同处理和收集日的小牛的粪便样本汇总,并用于确定艾美球虫个体的患病率。未检测到小牛体重或生长率的治疗效果(P≥0.51)。OPG的治疗×日相互作用检测(P<0.01),因为从第7天开始,与CON小牛相比,NAR和MON小牛的OPG较少(P<0.01)。与第7、14和28天的NAR小牛相比,MON中的OPG也较少(P≤0.03),但在第21、35和42天没有差异(P≥0.48)。在所有艾美球虫属物种中计算时,NAR和MON的抗球虫功效没有差异(P≥0.16)。,或根据牛E.Bovis和E.alabamensins的患病率。检测到治疗×日相互作用(P=0.04)的抗球虫功效。MON小牛在第7天和第14天更大(P<0.01),之后没有差异(P≥0.40)。总的来说,完成42天研究后,两种离子载体在控制球虫病方面同样有效,尽管莫能菌素的抗球虫作用已在实验早期指出。尽管如此,这些结果证实narasin是一种有效的抗球虫离子载体,用于自然感染的小牛。
This experiment compared narasin and monensin as anticoccidials for calves naturally infected with Eimeria spp. Twenty-four weaned, non-castrated male calves (Bos indicus × B. taurus cross) were assigned to this experiment (days -8 to 42). All calves were infected by Eimeria spp. according to oocyst count per gram (OPG) from fecal samples collected on days -8 and -7 (average 1,059 ± 101 oocysts/g). Calves were housed in individual pens, received corn silage, mineral mix, and water for ad libitum consumption, in addition to a grain-based supplement at 200 g/head daily. Fecal samples were collected on days -2 and -1 for OPG, and results averaged as initial OPG value. Calves were blocked according to initial OPG into eight blocks of three calves each, ranked within each block according to body weight (BW) recorded on day -1, and assigned to receive narasin (NAR; 0.8 mg/kg of BW), monensin (MON; 1 mg/kg of BW), or no ionophore (CON; negative control).
Ionophores were added to the grain-based supplement, and offered from days 0 to 42 of the experiment. Calf BW was recorded on days 7, 14, 21, 28, 35, and 42. Fecal samples were collected on days 6 and 7, 13 and 14, 20 and 21, 26 and 27, 34 and 35, and 41 and 42 for OPG analysis, and results from samples collected on consecutive days were averaged. Aliquoted fecal samples were also pooled across calves from the same treatment and collection days, and used to determine the prevalence of individual species of Eimeria. No treatment effects were detected (P ≥ 0.51) for calf BW or growth rate. A treatment × day interaction was detected (P < 0.01) for OPG, as NAR and MON calves had less (P < 0.01) OPG compared with CON calves beginning on day 7. The OPG was also less (P ≤ 0.03) in MON compared with NAR calves on days 7, 14, and 28, but did not differ (P ≥ 0.48) on days 21, 35, and 42. The anticoccidial efficacy of NAR and MON did not differ (P ≥ 0.16) when calculated across all Eimeria spp., or according to prevalence of E. bovis and E. alabamensins. A treatment × day interaction was detected (P = 0.04) for anticoccidial efficacy to E. alabamensis, which was greater (P < 0.01) in MON calves on days 7 and 14 and did not differ (P ≥ 0.40) afterward. Collectively, both
ionophores were similarly effective in controlling coccidiosis upon completion of the 42-d study, although the anticoccidial effects of monensin were noted earlier in the experiment. Nonetheless, these results corroborate narasin as an efficient anticoccidial ionophore for naturally infected calves.