Changes in serum related hormones levels in offspring lambs after immunisation of SS DNA vaccine. A, SS concentration (pg/ml) in T and C groups at week 9 of lactation; B, GH concentration (ng/ml) in T and C groups at week 9 of lactation; C, IGF-1 concentration (ng/ml) in T and C groups at week 9 of lactation; D, PRL concentration (uIU/ml) in T and C groups at week 9 of lactation, Data are shown as means ± SD. *P < 0.05.