THE POTENTIAL OF IMMUNO-NEUTRALIZATION OF SOMATOSTATIN FOR IMPROVING PIG PERFORMANCE

Immuno-neutralization of somatostatin (SRIF) has shown some promise as a technique for the enhancement of growth and lactation performance i n sheep and cattle. In pigs, active immunization against SRIF has fail ed to promote growth. While a more consistent GH response to GRF injec tions in SRIF-immunized pigs has been described, the effects of this a pproach on mean plasma GH, IGF-I and thyroxine levels are equivocal. S ince reproductive functions in the pig are affected by GH as well and since the existence of SRIF-like immunoreactivity has been proven in p orcine ovaries, the influence of immuno-neutralization of SRIF on repr oductive performance has also been investigated. In one report ovulati on rates and first litter size tended to be higher, while own work onl y describes adverse effects on ovarian activity. Although passive tran sfer of immunity against SRIF through colostrum to litters has been sh own, preweaning survival and mean pig weaning weight were not improved . In conclusion, so far there is no indication to suggest that in the near future immuno-neutralization of SRIF might become a practical too l to improve pig performance, possibly because of the poor antibody re sponse in pigs. In addition evidence exists in vivo and in vitro, that SRIF besides its well known negative effect, may also stimulate GH re lease providing another possible explanation why all attempts to impro ve pig performance through immuno-neutralization of SRIF have failed s o far.