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Research was conducted on commercial swine operations to determine whether plasma urea concentrations could be used as an indicator of the protein requirement of growing-finishing pigs. The research consisted of a 30-question survey and an on-farm visit to collect blood and feed samples. The survey included questions about genetics, nutrition, housing and health. Results showed that when plasma urea concentrations were analyzed across all phases of production, barrows had greater plasma urea concentrations than gilts. Plasma urea concentrations varied between the different phases of production, with nursery pigs having the lowest plasma urea concentrations, followed by growing and finishing pigs, respectively. An increase in dietary crude protein resulted in an increase of plasma urea in barrows and gilts in all phases of production. The comparison of dietary crude protein concentrations and age of the pigs at the time of blood collection indicates that the majority of the diets were over-formulated for crude protein. The effects of sex, crude protein, and phase of production on plasma urea concentrations in pigs raised on commercial operations were similar to those in a research setting. These results suggest that within an individual swine operation, plasma urea is a useful indicator of the protein requirement of growing-finishing pigs.