Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523, USA.
Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
J Anim Sci. 2024 Jan 3;102. doi: 10.1093/jas/skae334.
Fetal infection with bovine viral diarrhea virus (BVDV) after 150 d results in transient fetal infections (TI). Twenty-five unvaccinated, yearling Hereford heifers, seronegative for antibodies to BVDV1 and BVDV2, were bred by artificial insemination with X chromosome-bearing sperm from 1 Angus sire to examine the impact of TI on postnatal growth, estimated dry matter digestibility, blood parameters, and carcass characteristics. On day 175 of pregnancy, dams were intranasally inoculated with either sham control or 4.0 log median tissue culture infectious dose noncytopathic type2 BVDV to generate control or TI offspring, respectively. All control dams remained seronegative and all BVDV-inoculated dams seroconverted by day 14 post-inoculation. All control offspring were seronegative and all TI offspring were seropositive for antibodies to type 2 BVDV at birth. All offspring were raised on pasture until weaning. At weaning, all calves were transported to our research feedlot facility, housed in 3 pens, and transitioned to a high-energy concentrate-based diet. Heifer body weights (BW) and jugular blood samples were collected every 28 d. On day 84 of the feeding period, titanium dioxide was added to the diet of 12, age-paired, individually fed, heifers (6 control and 6 TI heifers; approximately 1 yr of age) for 28 d and used to estimate dry matter digestibility. On days 105 and 240 ruminal fluid (approximately 900 mL) was collected from every animal using a stomach pump and analyzed for short-chain fatty acids (SCFA). After approximately 287 d on feed, heifers were transported to a USDA-inspected abattoir and harvested. TI heifers had lighter final BW (P < 0.04) when compared to control heifers. Average daily gain was greater (P < 0.01) in control compared to TI heifers. TI heifers had a 2.2% lesser (P < 0.05) apparent dry matter digestibility, lighter (P < 0.01) hot carcass weights, but similar ruminal SCFA compared to controls. Blood glucose concentrations were similar (P > 0.8) between control and TI heifers. Ceruloplasmin activity (P < 0.03) and the oxidized form of glutathione (GSSG; P < 0.01), indicators of chronic inflammation, were increased in plasma from TI heifers compared to controls. Other indicators of oxidative stress were not impacted (P > 0.10) by TI status. These data suggest that fetal BVDV transient infection negatively impacts growth throughout the feeding period, possibly by impacting gastrointestinal tract function and increasing systemic inflammation.
牛病毒性腹泻病毒（BVDV）在 150 天后感染胎儿会导致短暂性胎儿感染（TI）。25 头未经免疫、年龄为 1 岁的海弗特小母牛，对 BVDV1 和 BVDV2 的抗体呈血清阴性，通过人工授精与来自 1 头安格斯种公牛的携带 X 染色体的精子交配，以检查 TI 对产后生长、估计干物质消化率、血液参数和胴体特征的影响。在妊娠 175 天时，用假对照或 4.0 log 中位数组织培养传染性剂量非细胞病变型 2 BVDV 对母羊进行鼻内接种，分别产生对照或 TI 后代。所有对照母羊仍保持血清阴性，所有 BVDV 接种母羊在接种后 14 天内血清转化。所有对照后代在出生时均对 2 型 BVDV 抗体呈血清阴性，所有 TI 后代均呈血清阳性。所有后代都在牧场上饲养，直到断奶。断奶时，所有小牛都被运送到我们的研究饲料场设施，关在 3 个畜栏中，并过渡到高能浓缩饲料为主的饮食。每隔 28 天采集一次小母牛的体重（BW）和颈静脉血样。在饲养期的第 84 天，将二氧化钛添加到 12 头年龄匹配、单独饲养的、小母牛（6 头对照和 6 头 TI 小母牛；大约 1 岁）的饮食中，持续 28 天，用于估计干物质消化率。在第 105 天和第 240 天，用胃泵从每只动物身上采集约 900 毫升瘤胃液，并分析短链脂肪酸（SCFA）。在饲料中约 287 天后，小母牛被运送到美国农业部检查的屠宰场并进行屠宰。与对照小母牛相比，TI 小母牛的最终 BW 较轻（P<0.04）。与 TI 小母牛相比，控制小母牛的平均日增重更大（P<0.01）。TI 小母牛的表观干物质消化率低 2.2%（P<0.05），热胴体重轻（P<0.01），但与对照相比，瘤胃 SCFA 相似。与 TI 小母牛相比，对照小母牛的血糖浓度相似（P>0.8）。TI 小母牛的血浆铜蓝蛋白活性（P<0.03）和氧化型谷胱甘肽（GSSG；P<0.01）升高，这是慢性炎症的标志物，与对照相比升高。其他氧化应激指标不受 TI 状态影响（P>0.10）。这些数据表明，胎儿 BVDV 短暂感染会在整个饲养期内对生长产生负面影响，可能是通过影响胃肠道功能和增加全身炎症。
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