Riboflavin requirement of gestating swine

Forty crossbred gilts (9 to 10 mo of age) were used to determine the riboflavin requirement for gestating swine. Upon mating, gilts were assigned to one of five levels of dietary riboflavin (.77, 1.77, 2.77, 3.77 or 4.77 ppm) and individually fed 2.0 kg daily of the assigned diet throughout gestation. Gilts were bled on d 7, 24, 30, 35, 40, 56, 70, 84, 90 and 97 postcoitum. On d 1 postpartum, all sows and their live piglets were bled. Hemolysates of isolated, washed erythrocytes were prepared from blood samples and assayed to establish the erythrocyte glutathione reductase activity coefficient (EGRAC) as an indicator of the riboflavin status of each animal. The higher the EGRAC, the greater the severity of the riboflavin deficiency. During gestation, the EGRAC of gravid gilts increased with time in a manner dependent upon the level of dietary riboflavin. Postpartal EGRAC were elevated in dams fed the three lowest levels of dietary riboflavin during gestation. Of the six gravid gilts fed .77 ppm riboflavin, four gilts gave birth, approximately 7 d prematurely, to stillborn litters while two gilts failed to farrow by 121 d postcoitum. Litter weights at birth and gestation weight gains of these gilts were less than those of gilts fed the higher levels of riboflavin. Postnatal mortality of piglets was greater for those litters from sows fed 1.77 ppm riboflavin than for those from sows fed higher levels of riboflavin. The riboflavin status of newborn piglets was similar to that of their dams as determined by EGRAC.(ABSTRACT TRUNCATED AT 250 WORDS)