SOMATOSTATIN IMMUNIZATION AND GROWTH OF LAMBS

Abstract

Twenty cross-bred lambs were used in a replicated design to measure the growth-promoting effect of immunization against somatostatin. The lambs were immunized against human alpha-globulin (control) or against somatostatin coupled to human alpha-globulin in a 1:3.75 ratio (wt/wt) (SI). The first immunization occurred when the lambs were 27 d old, followed by three additional immunizations at 2-wk intervals. Growth was monitored from first immunization until the lambs were 103 d old. At the age of 103 d the SI lambs were heavier than the control lambs (33.2 ± 1.1 (mean ± standard error) vs. 30.1 ± 1.4 kg, P < 0.05). The average daily gain after first immunization of the SI lambs was 17% greater than that of the control lambs (310 ± 10 vs. 265 ± 10 g day −1 , P < 0.05). Growth hormone and insulin secretory responses to glucose and arginine, glucose tolerance and somatomedin levels in plasma were not different between groups. Somatostatin immunization increased growth in lambs, but the mechanisms through which this occurs are not clear. Key words: Somatostatin, immunization, growth, lambs