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The use of additives such as ractopamine (RAC) in sows during early-mid gestation is an alternative to increase fetal growth and litter performance. However, although RAC supplementation in finishing pigs has the potential to improve the rate and efficiency of lean muscle growth, it can lead to behavioral and physiological changes similar to the typical stress responses. Therefore, the aim of the present study was to evaluate the effects of dietary supplementation with RAC in gestating sows from day 25 to 50 of gestation (pre-hyperplastic stage) on piglet’s vitality, blood parameters, muscle fibers parameters in semitendinosus muscle and developmental characteristics of piglets from birth towards weaning. For that purpose, a total of forty-one hybrid sows were divided into three dietary treatments: (1) control diet without RAC (CON), (2) control diet supplemented with of 10 mg/kg of RAC (RAC10) and (3) control diet supplemented with of 20 mg/kg of RAC (RAC20).
As a result, higher numbers of low-vitality piglets were observed in RAC-fed sows, regardless of the dose, compared with the control group. Regarding blood parameters, very low-density lipoprotein (VLDL) levels were lower in the RAC10 group when compared with the RAC20 group at day 21. The hematocrit was greater and the mean corpuscular hemoglobin concentration was lower in piglets from RAC-fed sows. As for litter performance, no significant statistical differences were detected regarding piglets’ body weight, average daily gain, blood gasometry or complete blood count. Moreover, no differences between treatments were observed in muscle fiber measurements in semitendinosus muscle.
In conclusion, the use of RAC in gestating sows reduced the vitality parameters of piglets and did not improve the performance from birth until weaning. Moreover, RAC did not negatively influence the hematological parameter and lipid metabolism. As the use of ractopamine is being restricted for pig production and no beneficial effects were observed in the present study, further research for alternative replacements is necessary.
Martinez CHG, Ravagnani GM, Muro BBD, Mendonça MV, Passarelli MS, Nakasone DH, Carnevale RF, Strefezzi RF, Martins SMMK, Andrade AFC. Dietary ractopamine supplementation of pregnant sows: what are the impacts on the neonate?. Animal. 2020; 14(1): 50-58. https://doi.org/10.1017/S1751731119001496