[The efficiency of and requirements for selected amino acids in growing female pigs. 3. Threonine].

With the help of an N utilization model by Gebhardt (1963) and its further development the threonine efficiency coefficients (kThr) of wheat, barley, maize, rye and peanut oil meal of different charges with a supply of L-lysine monohydrochloride, DL-methionine and DL-tryptophan was ascertained with a total of 59 female pigs of the local breed (35-45 kg live weight) by means of an N balance method. The variation range of kThr was between 0.61 and 0.87 based on a threonine effectivity of wheat gluten with lysine as standard. The derived threonine requirement for 100 g daily protein retention with a live weight of 40 kg was ascertained as 6.9 g (kThr = 1) and 9.6 kg (kThr = 0.71 as mean values of the protein sources studied). The proof of threonine limitation in the protein sources was provided by the supplementation of DL threonine.