Call conferences of co-operative associations of producers of farm products organized under or subject to the provisions of chapter seventy-seven of the consolidated laws   1 for discussion of cost of production, transportation and marketing, of market conditions and prices for sale of farm products to the end that the marketing operating operations for such co-operative associations may be facilitated, made more efficient and the producers may obtain the reasonable cost of production, plus cost of compliance with sanitary regulations affecting production or marketing.  Such conferences shall be held under the supervision of the commissioner.  Neither such conferences nor any agreements or arrangements resulting therefrom, if such agreements or arrangements are approved by the commissioner, shall be deemed or construed to be acts, conspiracies, agreements or arrangements in restraint of trade or commerce or injurious to public welfare.  The powers hereby conferred may also be exercised in conjunction with officials or representatives of the federal government.