Responses of pregnant ewes and young lambs to ovalbumin immunization, antiovalbumin antibody transfer to lambs, and temporal changes in antiovalbumin antibody

Authors: LEWIS, GREGORY - Retired ARS Employee; Wang, Shiquan; Taylor, Joshua - Bret

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2017
Publication Date: 12/1/2017
Citation: Lewis, G.S., Wang, S., Taylor, J.B. 2017. Responses of pregnant ewes and young lambs to ovalbumin immunization, antiovalbumin antibody transfer to lambs, and temporal changes in antiovalbumin antibody. Journal of Animal Science. 1:585-591.

Interpretive Summary: Newborn lambs are born without a fully developed immune system. In order for newborn lambs to have optimal health and the greatest chances of survival, they must acquire “passive immunity” by consuming their mother’s (i.e., the ewe’s) colostrum soon after birth. Colostrum is rich in important antibodies that protect lambs from common diseases found in lambing systems. Factors that affect how long these passive-transfer antibodies will protect a newborn lamb against disease are not well understood. Furthermore, the age that a lamb should be before it can respond to a vaccination is not exactly known. Therefore, our aim was to identify a management strategy that would result in the best antibody protection in newborn lambs. We compared vaccination of pregnant ewes before lambs were born with vaccination of lambs immediately after birth or at 28 days of age. We found that the ewe’s antibodies that were produced in response to vaccinations during late pregnancy were transferred to lambs via colostrum. However, vaccinating lambs immediately after birth may interfere with the ewe’s antibodies that the lamb acquired from the colostrum. When considering the optimal time to vaccinate a lamb, waiting until the lamb was 28 days of age was far superior to vaccinating the lamb at birth for initiating antibody production by the lamb. Overall, the results of this study support the recommendations to vaccinate ewes against common pathogens during late pregnancy and to ensure that lambs receive adequate colostrum soon after birth. The results of this study do not support the notion of vaccinating lambs immediately after birth, instead of inoculating late pregnant ewes and gaining the colostrum-mediated advantages of passive immunity.

Technical Abstract: Factors affecting the decay of maternally derived IgG and ability of neonatal lambs to produce protective amounts of their own IgG are not well understood. Thus, we conducted 3 experiments to quantify the 1) response of pregnant ewes to ovalbumin immunization, 2) antiovalbumin antibody (OV-IgG) transfer to lambs, 3) changes over time in OV-IgG in lambs, and 4) response of young lambs to ovalbumin immunization. In Exp. 1, ewes (n = 10/group) either received control (adjuvant + saline) or ovalbumin (ovalbumin + adjuvant + saline) injections at ˜ 42 and 14 d prepartum. Ovalbumin increased (P < 0.001) ewe serum and colostrum OV-IgG. Serum OV-IgG was greater (P < 0.0001) in lambs from ovalbumin-treated than in lambs from control ewes. In Exp. 2, lambs (n = 20/group), which were from ewes that had received ovalbumin prepartum, were given either control or ovalbumin injections on d 1 and 15 of age. From d 1 to 15, maternally derived OV-IgG was less (P < 0.04) in ovalbumin-treated than in control lambs. After d 15, OV-IgG was greater (P < 0.001) in ovalbumin-treated than in control lambs. In Exp. 3, lambs (n = 20/group), which were from ewes naïve to ovalbumin, received 1 of 4 treatments: 1) d-1 + d-15 control injections; 2) d-1 + d-15 ovalbumin; 3) d-28 + d-42 control; 4) d-28 + d-42 ovalbumin. In d-1 + d-15 ovalbumin lambs, OV-IgG increased (P < 0.001) from d 7 to 21 after treatment and then decreased (P < 0.004) after d 28. In d-28 + d-42 ovalbumin lambs, OV-IgG increased (P < 0.001) steadily until d 21 after treatment and then stabilized after d 21. At ˜ 159 d of age, these lambs received injections consistent with their original type. After the d-159 treatment, ovalbumin injection increased (P < 0.0001) OV-IgG, and the injection type × time interaction was significant (P < 0.0001). In d-28 + d-42 ovalbumin lambs, OV-IgG, just before the d-159 injections, was greater (P < 0.006) than that in the other groups. In this study, late pregnant ewes produced OV-IgG after ovalbumin injections and then transferred OV-IgG to lambs via colostrum. Ovalbumin treatment of young lambs reduced circulating maternally derived OV-IgG, but it also induced an immune response in the lambs. Overall, our results support recommendations to vaccinate ewes against common pathogens during late pregnancy and to ensure that lambs receive adequate colostrum soon after birth.