― 1. In two experiments samples of blood and organs were taken from newborn and young lambs born to five groups of ewes that received different dietary iodine (I) levels. Dietary I contents (mg/kg dry matter [DM]) in pregnancy and lactation, respectively, were : Experiment 1 -0.36 and 0.26 for group C, 2.01 and 1.94 for group D; Experiment 2 -0.13 and 0.12 for group A, 0.22 and 0.20 for group B, 10.77 and 8.88 for group E. 2. I intake of ewes had no effect on birthweight, body weight gain, or

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... rtality between birth and wk 2 of life. No difference between the groups was recorded in the weights of brain, heart, lungs, and liver of lambs killed at birth. However, the weight of both the thyroid lobes in lambs from group E was lower than that of the other groups. The I content of the thyroid lobes of lambs from group A was 30-40% lower than that of the other groups. 3. The plasma inorganic iodine (PII) of lambs from birth to d42 of life was affected by ewe I intake, except for groups A and B, during the first 16 h of life. The Pll of lambs increased with the I intake via milk in each group. The ratio of Pil of lambs at birth/Pll of ewes at d7 prepartum was 3.77, 2.96, * Part 1 of this article was published in Reprod. Nutr. Develop. (1989) 29, 113. ** Present address : Station de Recherches Zootechniques, INRA, CRAAG, BP 1232, 97184 Pointeà-Pitre Cedex, Guadeloupe. ingérée par la brebis n'a pas modifié les poids du cerveau, du coeur des poumons et du foie des agneaux à la naissance. Le poids des lobes thyroïdiens des agneaux à la naissance du lot E était inférieur à ceux des autres lots. La teneur en iode des lobes thyroïdiens des agneaux du lot A était 30-40% inférieure à celle des autres lots. 3. La teneur en iodure du plasma des agneaux de la naissance au 42e jour de vie est sous la dépendance de la teneur en iode du régime des brebis excepté pour les lots A et B. Le rapport iodures plasmatiques des agneaux à la naissance sur iodures plasmatiques des brebis était égal à 3,77, 2,96, 1,68, 1,39 et 8,62 respectivement pour les groupes A, B, C, D et E. 4. L'ingestion d'iode en excès (lot E) a induit une augmentation de la thyroxinémie des agneaux à la naissance. Ceci a diminué le taux plasmatique d'immunoglobulines G des agneaux de ce lot. iodeagneaux nouveau-nésiodure plasmatiquethyroxinetriiodothyronineimmunoglobulines G