Muscle Fiber Number and Growth Performance of Pigs from Sows Treated with Ractopamine

  • Hoshi, E.H. (Animal Science Department, Londrina State University) ;
  • Fonseca, N.A.N. (Animal Science Department, Londrina State University) ;
  • Pinheiro, J.W. (Animal Science Department, Londrina State University) ;
  • Bridi, A.M. (Animal Science Department, Londrina State University) ;
  • Silva, C.A. (Animal Science Department, Londrina State University)
  • Received : 2004.09.26
  • Accepted : 2005.03.25
  • Published : 2005.10.01


The goal of the trial was to evaluate the effects of ractopamine (20 ppm in the ration) given pregnant sows during three different pregnancy stages (T1: 25 to 50 d; T2: 50 to 80 d; T3: 25 to 80 d of gestation, and T4: control-no ractopamine) on fetal muscle development (through counts of the number of fibers of the semitendinosus muscle), on the growth and carcass characteristics of the progeny. Forty eight weaned piglets (12 per treatment) were assessed for number of muscle fibers, while performance and carcass characteristics were evaluated on a separate 48 animals (12 per treatment) grown to 100 kg. Animals produced by sows treated from 25 to 50 d of pregnancy (T1) resulted in non-significant increase of 6.85% in the number of muscle fibers in the semitendinosus muscle when compared to animals from the control group. Performance results were significantly different (p<0.05), and animals produced by sows from the T1 group gained more weight during the growth I stage (25 to 50 kg) and during the total period (6 to 100 kg) (991 vs. 903 grams, and 844 vs. 772 grams, respectively) when compared to controls. For carcass characteristics, results showed that animals produced by the T1 group of sows were heavier at slaughter (p<0.05) when compared to the controls (T4) (100.17 vs. 93.09 kg). There was a positive correlation between number of muscle fibers and bodyweights, carcass weights, Longissimus dorsi muscle depth and dressing out (0.80, 0.86, 0.67, and 0.50, respectively). Sows treated with ractopamine between 25 to 50 d of pregnancy produced piglets that performed better and had superior carcass characteristics than those produced by untreated sows. The ractopamine used for pregnancy sows (25 to 50 d) can be indicated as a device to increase the progeny performance.


Pigs;Muscle;Myofibers;Performance;Carcass;Beta-adrenergic Agonis


  1. Handel, S. E. and N. C. Stickland. 1987. Muscle cellularity and birth weight. Anim. Prod. 44:311-317.
  2. Kim, Y. S., R. D. Sainz, J. Ferlazzo and N. M. Tulloh. 1994. Effect of maternal administration of salbutamol to sows on postnatal growth and carcass characteristics in the progeny. Aust. J. Agric. 45(2):271-278.
  3. Miller, L. R., V. A. Garwood and M. D. Judge. 1975. Factors affecting porcine muscle fiber type, diameter and number. J. Anim. Sci. 41:66-77.
  4. Moody, D. E., D. L. Hancock and D. B. Anderson. 2000. Phenethanolamine repartitioning agents. In: CAB International. Farm animal metabolism and nutrition (Ed. J. P. F. D´Mello), Wallinford, Oxon. pp. 65-95.
  5. Irgang, R., A. L.Guidoni, D. Berlitz and C. Corso. 1997. Equa$\c{c}$$\~{o}$es para estimar rendimento e quantidade de carne em carca$\c{c}$as de su$\'{\i}$nos. Proceedings Congresso Brasileiro de Veterin$\'{a}$rios Especialistas em Su$\'{\i}$nos, Foz do Igua$\c{c}$u, Brazil. pp. 403-404.
  6. Dwyer, C. M., J. M. Fletcher and N. C. Stickland. 1993. Muscle cellularity and postnatal growth in the pig. J. Anim. Sci. 71:3339-3343.
  7. Dwyer, C. M., N. C. Stickland and J. M. Fletcher. 1994. The influence of maternal nutrition on muscle fiber number development in the porcine fetus and on subsequent postnatal growth. J. Anim. Sci. 72:911-917.
  8. SAS. 1998. SAS/$STA^{\circledR}$ User’s Guide. SAS Inst. Inc., Cary, NC.
  9. Wigmore, P. M. C. and N. C. Stickland. 1983. Muscle development in large and small pig fetuses. J. Anat. 137:235-245.
  10. National Research Council (NRC). 1998. Nutrient requirements of swine. 10th ed. Washington: National Academy Press. p. 189.
  11. Ricks, C. A., P. K. Baker and R. H. Dalrymple. 1984. Use of repartioning agents to improve performance and body composition of meat animals. Proc. Reciprocal Meat Conf. 37:5-11.

Cited by

  1. Increased sow nutrition during midgestation affects muscle fiber development and meat quality, with no consequences on growth performance1 vol.87, pp.2, 2009,