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.
Keywords: apparent digestibility; epigenetics; oxidative stress; transient infection.
Fetal infection with bovine viral diarrhea virus (BVDV) after 150 d of gestation results in transient fetal infections (TI). Once the TI calf is born, it is negative for BVDV RNA but positive for BVDV-specific antibodies in blood. To investigate the effect of fetal TI on postnatal growth performance, blood parameters, and apparent dry matter digestibility, TI (n = 11) and control (n = 12) heifer calves were generated by inoculating pregnant heifers with a medium containing noncytopathic BVDV type 2 or a sham control medium on day 175 of pregnancy. Following weaning (approximately 7 mo of age), calves were fed a standard high concentrate finishing feedlot diet for approximately 287 d. Body weights and jugular blood samples were collected every 28 d. An indigestible feed marker was also added to the diet to estimate apparent dry matter digestibility. The average daily gain was greater in control compared to TI heifers. Apparent dry matter digestibility and hot carcass weights were reduced in TI heifers compared to controls. Indicators of chronic inflammation (ceruloplasmin activity and reduced glutathione) were increased in blood from TI compared to control offspring. These data indicate that BVDV infection initiated during the second trimester of pregnancy reduces offspring performance which could impact overall profitability.
© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.