Evaluation of the Effects of Colostrum Substitutes on IgG Levels and Humoral Immune Development in Polypay Lambs

This study investigated colostrum source impact on passive immunity transfer and humoral immune development in Polypay lambs. Newborn lambs (4.80 ± 0.33 kg BW) were assigned to four groups: fresh ewe colostrum (FrC; <i>n</i> = 10), frozen ewe colostrum (FZ; <i>n</i> = 11), frozen cattle colostrum (CC; <i>n</i> = 11), or artificial cattle colostrum (AC; <i>n</i> = 11). Lambs received 65 mL/kg colostrum within 4 h post-parturition and were raised on milk replacer, creep feed, and hay until weaned (28 days of age [d]). Immunoglobulin G concentrations were measured at birth and then weekly until 28 d. Lambs were immunized with 1 mL ovalbumin (2 mg/mL PBS) at 35 and 63 d. Ovalbumin-specific antibodies were quantified. A tendency (<i>p</i> = 0.06) suggested FrC yielded higher relative IgG at later time points (7, 14, 21, and 28 d) compared to FZ. Frozen cattle colostrum resulted in significantly (<i>p</i> = 0.02) higher IgG concentrations than AC at 24 h, 7, 14, and 21 d. Fresh ewe colostrum and AC showed a faster (1 week-post-immunization) and more robust (>175%; <i>p</i> ≤ 0.07) ovalbumin humoral response compared to CC lambs 2 to 8 weeks-post-immunization. Fresh ewe colostrum seems to provide the best passive and adaptive immunity compared to other colostrum sources. Moreover, our results suggest that the best colostrum alternative for newborn lambs is frozen ewe colostrum.