ROLE OF DIETARY LIPIDS ON FETAL TISSUE FATTY-ACID COMPOSITION AND FETAL SURVIVAL IN SWINE AT 42 DAYS OF GESTATION

Eighty-six crossbred (Duroc x Yorkshire) gilts were used in two trials to assess the effect of supplemental dietary fats during early gestation on fetal survival, fetal development, and fatty acid (FA) composition in gilt plasma and fetal head and body at d 37 to 45 after breeding. Three diets contained 4% (wt/wt) added fat either as coconut, soybean (SO), or menhaden oils (MO). A fourth diet containing corn starch approximately isoenergetic to the quantity of the oils was used as a control. Across both trials, fetal survival percentage did not differ (P >.10) according to treatment, but in Trial 2 fetal survival was higher (P <.06) for gilts fed the MO diet than for gilts fed the control diet. The FA composition of plasma of gilts at slaughter and the conceptus tissues were similar; both were influenced by the FA composition of the diets. The ratio of n-3:n-6 FA was higher in conceptus tissue than in maternal plasma and the ratio was higher (P <.05) for the MO diet than for, the other diets. Subsequently, a total of 46 multiparous females were used in three trials to further evaluate the effects of MO on percentage of fetal survival relative to the corn starch control diet; the results demonstrated no differences (P >.10) in percentage of fetal survival due to the addition of MO. The high percentage of fetal survival observed in gilts on all the treatments and the unequal ovulation rate in sows on different oil diets precluded definitive conclusions regarding the effects of supplemental oil on fetal survival. Further research is necessary to determine whether an altered dietary FA composition, and the resultant altered FA composition of fetal tissues, contributes to improved fetal survival; however, SO, a supplier of the 18-carbon omega-3 FA alpha-linolenic acid, did not provide the same FA composition in plasma and conceptus tissue that MO, a supplier of preformed long-chain omega-3 FA (20:5n-3 and 22:6n-3), provided.