ELUCIDATING DIFFERENT CLOSTRIDIUM PERFRINGENS TYPE D VACCINE PROTOCOLS IN EWES AND LAMBS

Enterotoxemia caused by Clostridium perfringens type D epsilon toxin (CptD ETX) is a major cause of sudden mortality in lambs. Protection of neonatal lambs relies heavily on maternally derived antibodies (MDA) transferred through colostrum; however, these antibodies may also influence the lamb’s immune response to vaccination. Therefore, the present study aimed to: (1) evaluate the effect of pre-lambing booster vaccination timing on ewe antibody responses and colostrum antibody transfer, (2) evaluate the transfer of passive immunity (TPI) in lambs, and (3) determine how lamb age at vaccination and maternal booster timing influence lamb vaccine antibody responses. Three trials were conducted in ewes and lambs, using a multivalent clostridial vaccine (Glanvac® 6, Zoetis Canada Inc., Kirkland, QC, Canada). In ewes, booster vaccinations were performed as follows: in trials 1 and 3, ewes were boosted 42-or-14 days (42d or 14d) pre-lambing; in trial 2, ewes were boosted 14d pre-lambing or received no booster. All ewes had a known primary and booster CptD vaccination history in previous years. A competitive ELISA was used to determine serum CptD ETX titers as inhibition %. CptD ETX were measured pre-vaccination, 14-days (-14d), and 7 days (-7d) pre-lambing, and at lambing (d 0). Lambs born to ewes in each trial were vaccinated at 3, 14, or 33/35 days (3d, 14d, 33/35d) of age, and serum CptD ETX antibody responses were monitored longitudinally up to 8-12 weeks from the day of vaccination. In ewes, booster at 42 d significantly (p<0.01) increased serum antibody titers at -7d compared with no booster (88.60% vs. 61.23%), although there was no difference at d 0 (p=0.34). Antibody responses were comparable between 42d and 14d groups (in trial 1 and 3) at both -7d and at d 0 (p=0.15 and p=0.07, respectively), and titer fold change from vaccination to -7d and d0 were also similar between booster groups (p=0.43 and p=0.13, respectively). Colostrum quality, assessed using Brix refractometry, was not influenced by any vaccination treatment (Brix % range: 28.53(± 4.75) to 31.52(± 3.17); lowest p=0.59). Likewise, TPI in lambs, evaluated at 36-48 hours of age, was not significantly different between lambs from different maternal booster groups in any trial, measured as serum total protein (TP) (lowest p=0.23), Brix% (lowest p=0.24), and ETX inhibition % (lowest p=0.08). Within each maternal booster group, lamb age (3 or 33 d in trials 1 and 2; 14 or 35d in trial 3) at primary vaccination did not significantly influence antibody titers at vaccination (lowest p trial 1: p=0.16; trial 2: p=0.36; trial 3: p=0.50) or over time (lowest p trial 1: p=0.36; trial 2: p=0.17; trial 3: p=0.39). However, among lambs from non-boosted ewes, antibody response trajectories differed between those vaccinated at 3d and 33d of age (p=0.02). When comparisons were made to see the effect of maternal booster timing, in trial 1 and 2, lambs vaccinated at 3d of age had a significantly lower antibody titers at pre-vaccination however, these lambs had a significant immune response following vaccination compared to lambs vaccinated at 3d but born to ewes booster-vaccinated at 42d (largest p=0.02, p<0.01, respectively). Interestingly, in 5 out of 6 comparisons, lambs from 42d boosted ewes had significantly higher circulating antibody concentrations pre-vaccination (largest p=0.04) compared to lambs from ewes boosted closer to lambing or not boosted at all. Pre-lambing booster vaccination enhanced maternal antibody responses regardless of timing. Colostrum quality and transfer of passive immunity were not affected by booster timing, providing producers with evidence-based flexibility in ewe vaccination scheduling. Importantly, maternal antibody levels influenced lamb vaccine responses in a dose-dependent manner: lambs with high pre-vaccination titers (>88% inhibition) showed minimal active responses, while those with moderate titers (~70%) mounted significantly stronger responses when vaccinated early (3 days of age). These findings support prioritizing ewe booster vaccination at 42 d pre-lambing as the cornerstone strategy, while early lamb vaccination (3 d) is recommended when maternal booster coverage is incomplete, allowing producers to tailor vaccination programs to their specific flock circumstances

Name thesis:degree_name

Master of Science (M.Sc.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Large Animal Clinical Sciences

Grantor

University of Saskatchewan

Year dc:date.issued

2026

Author dc:creator

• Muthukumara, Suren

Advisor dc:contributor.advisor

• Uehlinger, Fabienne Dominique

Committee members dc:contributor.committeemember

• Dadrwal, Dinesh
• de Oliveira Costa, Matheus
• Van Cleef, Eric

• sheep
• Clostridium perfringens type D
• booster vaccination
• antibody concentrations

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10388/18807

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/18807