Which clinical sign is associated with fetal exposure to mimosine in ruminants?

The correct answer is associated with congenital defects such as goitre, which can arise from fetal exposure to mimosine in ruminants. Mimosine is a toxic amino acid found in certain plants, particularly in the Leucaena species, which can disrupt normal thyroid function in animals. When pregnant ruminants ingest mimosine, it can lead to interference in the synthesis of thyroid hormones in the developing fetus. This disruption can result in conditions such as goitre, a swelling of the thyroid gland, due to inadequate levels of thyroid hormone.

In contrast, the other options do not directly correlate with the effects of mimosine exposure. Enlarged kidney size is not a known consequence of mimosine toxicity; rather, it may relate to different conditions or toxins affecting renal function. Increased muscle mass has no established link to mimosine toxicity and would not typically be a recognized outcome of fetal exposure to this compound. Nervous system abnormalities, while potentially connected with other toxins or stresses, are not specific consequences of mimosine exposure in ruminants. Consequently, the relationship between mimosine and congenital defects such as goitre is well-documented, affirming that option highlighting these defects is indeed the correct choice.