Research conducted by USDA's Agricultural Research Service and the University of Missouri shows pigs injected with dexamethasone grew 12% faster in their first 18 days of life. Dexamethasone is a synthetic version of a type of hormone called corticoid that is naturally produced by animals under stress.
In the research, 40 crossbred pigs were assigned by birth weight and sex to either sterile saline (10 boars and 10 gilts) or dexamethasone treatment (10 boars and 10 gilts).
Pigs were injected with 0.45 mg. of dexamethasone or saline per lb. of body weight within one hour of birth.
Weights were recorded on days 0, 7, 14 and 18. On day 17, pigs were fitted with a jugular catheter for blood sampling.
Birth weights (3.37 0.09 lb.) did not differ between the control and treatment pigs.
The researchers found a 12.2% increase in average daily gain (ADG) for the dexamethasone pigs. Dexamethasone-treated pigs gained 0.63 lb./day, compared to control group gains of 0.56 lb./day.
Weights at 18 days averaged 15.5 lb. for the dexamethasone pigs and 14.1 lb. for the control pigs.
Blood samples were taken at 15-minute intervals to determine serum concentration of growth hormone (GH), insulin-like growth factor (IGF-1) and IGF-2.
Then, pigs were sacrificed for tissue collection for RNA samples from the pituitary, liver and longissimus dorsi muscle.
The researchers found higher concentrations of IGF-1 and lower concentration of GH and IGF-2 in dexamethasone-treated pigs.
Based on the results, dexamethasone treatment at birth enhances growth during the first 18 days of life.
The researchers find that the early neonatal period may be an opportune time to alter physiological factors that influence growth.
Current research projects are investigating if the dexamethasone effect is maintained throughout the grow/finish phase and if there are changes in carcass quality.
Researchers: Jeffery Carroll, ARS, Columbia, MO; Tim Safranski and Johnna Seaman, both from the University of Missouri.
Contact Carroll at (573) 884-4798 or carrollja@missouri.edu.