Fetal infection of bovine viral diarrhea virus (BVDV) before d 125 to 150 of gestation results in the birth of immunotolerant, persistently infected (PI) calves. Infection of BVDV during late gestation results in transient fetal infections (TI). Unvaccinated, yearling Hereford heifers (n = 25), seronegative for antibodies to BVDV1 and BVDV2, were bred by artificial insemination with X chromosome-bearing sperm from an Angus sire to examine the impact of TI on postnatal growth, estimated dry matter digestibility, blood glucose concentrations, and carcass characteristics. On d 175 of pregnancy, heifers were intranasally inoculated with either DMEM + 2% horse serum (sham control) to generate control calves or 4.0 log TCID50 noncytopathic type2 BVDV to generate TI calves. All sham-inoculated control dams remained seronegative, and all BVDV-inoculated dams seroconverted by d 14 post-inoculation. Sham-inoculated control dams (n = 12) and BVDV-inoculated dams (n = 12) gave birth to live calves. 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 feedlot research facility, housed in one group feedlot pen, and transitioned to a high-energy concentrate-based diet until reaching an approximate BW of 600 kg. Upon arrival at the feedlot, all animals received a standard heifer growth implant, a modified live viral vaccine containing IBR-BRSV-PI3 and were dewormed. Heifer BW and jugular blood samples were collected every 28 d. On d 84 of the feeding period, titanium dioxide was added to the diet of 12, age-paired, individually fed, heifers (3 control and 3 TI heifers; approximately 1 yr of age) for 28 d and used to estimate dry matter digestibility. After approximately 280 d on feed heifers were transported to a USDA-inspected abattoir and harvested. The TI heifers had lighter birth weights (P < 0.03) and final BW (P < 0.04) when compared with control heifers. Average daily gain was greater (P < 0.01) in control compared with TI heifers. Blood glucose concentrations were similar between control and TI heifers at all sampling time points. Dry matter intake of individually fed heifers was similar across treatments. TI heifers had a 2.2% lesser (P < 0.05) dry matter digestibility and lighter (P < 0.01) hot carcass weights compared with controls. These data suggest that TI fetal BVDV infection negatively impacts growth throughout the feeding period, possibly by impacting gastrointestinal tract function. This research was supported by USDA-NIFA Grant # 2019-67015-29866.

中文翻译：

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PSIV-15 一过性胎牛病毒性腹泻病毒感染对出生后生长、估计干物质消化率、葡萄糖浓度和胴体特性的影响


妊娠 125 至 150 天前胎儿感染牛病毒性腹泻病毒 （BVDV） 会导致免疫耐受、持续感染 （PI） 的犊牛出生。妊娠晚期感染 BVDV 会导致短暂性胎儿感染 （TI）。未接种疫苗的一岁赫里福德小母牛 （n = 25），BVDV1 和 BVDV2 抗体血清反应阴性，通过来自安格斯公牛的携带 X 染色体的精子进行人工授精繁殖，以检查 TI 对出生后生长、估计干物质消化率、血糖浓度和胴体特征的影响。在怀孕第 175 天，小母牛鼻内接种 DMEM + 2% 马血清（假对照）以生成对照犊牛或 4.0 log TCID50 非细胞病变性 2 型 BVDV 以生成 TI 犊牛。所有假接种的对照水坝保持血清阴性，所有 BVDV 接种的水坝在接种后第 14 天进行血清转化。假接种的对照母牛 （n = 12） 和接种 BVDV 的母牛 （n = 12） 生下了活犊牛。所有对照后代均呈血清阴性，所有 TI 后代出生时 2 型 BVDV 抗体血清反应阳性。所有后代都在牧场上饲养，直到断奶。断奶时，所有犊牛都被运送到我们的饲养场研究设施，饲养在一个饲养场群中，并过渡到以高能量精料为基础的日粮，直到达到大约 600 公斤的体重。到达饲养场后，所有动物都接受了标准的小母牛生长植入物，这是一种含有 IBR-BRSV-PI3 的改良活病毒疫苗，并进行了驱虫。每 28 d 收集 Heifer BW 和颈静脉血样。 在饲喂期的第 84 天，将二氧化钛添加到 12 头年龄配对、单独饲喂的小母牛（3 头对照小母牛和 3 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。大约 280 天后，将小母牛运送到经 USDA 检查的屠宰场并收获。与对照小母牛相比，TI 小母牛的出生体重 （P < 0.03） 和最终体重 （P < 0.04） 较轻。与 TI 小母牛相比，对照组的平均日增重更高 （P < 0.01）。在所有采样时间点，对照小母牛和 TI 小母牛的血糖浓度相似。单独饲喂的小母牛的干物质摄入量在不同处理中相似。与对照组相比，TI 小母牛的干物质消化率降低了 2.2% （P < 0.05），热胴体重量较轻 （P < 0.01）。这些数据表明，TI 胎儿 BVDV 感染可能通过影响胃肠道功能，在整个喂养期间对生长产生负面影响。这项研究得到了 USDA-NIFA Grant # 2019-67015-29866 的支持。