Höglund Johan, Hessle Anna, Zaralis Konstantinos, Arvidsson-Segerkvist Katarina, Athanasiadou Spiridoula
Swedish University of Agricultural Sciences, Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, P.O. Box 7036, Uppsala, Sweden.
Swedish University of Agricultural Sciences, Department of Animal Environment and Health, Section of Production Systems, P. O. Box 234, SE-532 23 Skara, Sweden.
Vet Parasitol. 2018 Jan 15;249:88-91. doi: 10.1016/j.vetpar.2017.11.011. Epub 2017 Nov 24.
Body weight gain (BWG) and gastrointestinal nematode challenge (GIN) were investigated in two genetically diverse groups of cattle. Thirty-two dairy calves (D=Swedish Red/Holstein) and 31 dairy×beef crosses (C=Swedish Red/Holstein×Charolais) pairwise matched by dam breed and birth dates, were monitored for ≈20 weeks on a pasture grazed by cattle in the previous year. At turn-out, animals (between 6 and 12 months age) from each genotype were either infected with 5000 third stage (L3) Ostertagia ostertagi (50%) and Cooperia oncophora (50%) larvae (H, high-exposure); or treated monthly with 0.5mg ivermectin (Noromectin, Pour-on) per kg bodyweight to remove worms ingested (L, low-exposure). Animals were weighed every fortnight and individual BWG was calculated. Faecal and blood samples were collected every four weeks throughout the experiment for nematode faecal egg counts (FEC) and larvae cultures and serum pepsinogen concentrations (SPC), respectively. Nematode eggs were observed 29 days post turn-out in both H groups. FEC peaked to around 200 eggs per gram (epg) on days 58 and 85 respectively in both H groups. FEC were also observed in the L groups at the same time, but mean epg remained very low (<20epg) and constituted exclusively of C. oncophora. Although, there was no significant difference in SPC values in animals of the different genotypes, ten animals of CH showed a SPC >3.5 IU tyrosine whereas only six DH animals reached similar pepsinogen levels. The level of infection (H and L) significantly affected BWG in both genotypes. Even though there was no statistically significant genotype (C or D)×treatment (H or L) interaction, there was a larger difference in body weight of H and L in C (37kg) compared to D (17kg) genotypes at the end of the experiment. Our data collectively support the view crossbred (C) animals experience the impact of gastrointestinal parasitism more severely compared to pure dairy (D) first season grazers. The mechanisms that underpin this remains speculative.
在两组基因不同的牛群中研究了体重增加（BWG）和胃肠道线虫攻击（GIN）情况。32头奶牛犊牛（D = 瑞典红牛/荷斯坦牛）和31头奶牛×肉牛杂交牛（C = 瑞典红牛/荷斯坦牛×夏洛来牛），按母本品种和出生日期进行配对，在前一年牛群放牧过的牧场上监测了约20周。放牧开始时，每种基因型的动物（年龄在6至12个月之间）要么感染5000条第三期（L3）奥斯特他线虫（50%）和牛库珀线虫（50%）幼虫（H，高暴露组）；要么每月按每千克体重0.5毫克伊维菌素（诺莫菌素，浇泼剂）进行处理以清除摄入的蠕虫（L，低暴露组）。每两周对动物称重并计算个体BWG。在整个实验过程中，每四周采集粪便和血液样本，分别用于线虫粪便虫卵计数（FEC）、幼虫培养以及血清胃蛋白酶原浓度（SPC）检测。在放牧开始后29天，两个高暴露组均观察到线虫卵。两个高暴露组的FEC分别在第58天和第85天达到峰值，约为每克200个虫卵（epg）。在同一时间低暴露组也观察到了FEC，但平均epg仍然很低（<20 epg），且全部由牛库珀线虫构成。虽然不同基因型动物的SPC值没有显著差异，但10头杂交牛的SPC > 3.5 IU酪氨酸，而只有6头奶牛犊牛达到了类似的胃蛋白酶原水平。感染水平（高暴露和低暴露）对两种基因型的BWG均有显著影响。尽管在基因型（C或D）×处理（高暴露或低暴露）之间没有统计学上的显著交互作用，但在实验结束时，杂交牛（C）中高暴露组和低暴露组的体重差异（37千克）比奶牛犊牛（D）（17千克）更大。我们的数据共同支持了这样一种观点，即与纯种奶牛（D）第一季放牧动物相比，杂交（C）动物遭受胃肠道寄生虫感染的影响更为严重。其背后的机制仍具有推测性。
