Abstract: Sachet and strip of sachets for packaging a biological liquid substance, such as animal semen. The sachet is formed by two coupled and welded films of supple plastic material, delimiting a reception pouch of the substance, which has at one of its ends an opening for filling the empty sachet by means of a hollow cylindrical needle. These films have a pair of welding lines which form tabs starting out from said opening and axially and symmetrically penetrating the internal space of the sachet by converging towards the interior of the latter, their free ends being spaced apart by a value “e” which is substantially equal to ?d/2, “d” being the value of the diameter of said needle, thus preventing the foam produced during filling from exiting the bag as the needle is withdrawn (F). Artificial insemination in breeding.