Abstract:
Use of low-test-weight corn in swine diets and the lysine/protein relationship in corn
Lee J. Johnston, PhD
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Poor growing conditions throughout the corn belt in recent years have produced a high proportion of low-test-weight (bulk density) corn. Nutritionists expect low-test-weight corn to be higher in protein and lower in energy compared with corn of normal test weight (72 kg per hl; 56 lb per bu). Recently, several research groups have evaluated the effect of low-test-weight corn on performance of growing-finishing pigs. Researchers at South Dakota State University reported an inverse relationship between the test weight of corn and digestibility of protein and dry matter with no effect on digestibility of acid detergent fiber (ADF) and neutral detergent fiber (NDF). In a companion study, daily weight gain was not different between pigs fed low (59 kg per hl; 46 lb per bu) compared with normal test weight corn. Four additional studies have reported no detrimental effects on growth performance of pigs when corn with test weight as low as 40 lb per bu was fed. No studies hove investigated the effects of low-test-weight corn on performance of breeding swine. Assuming that mycotoxins and such factors as molds and overheating are not compromising corn quality, low-test-weight corn seems to be comparable in feeding value to normal-test-weight corn for pigs.
Several researchers have attempted to predict Iysine content of corn using crude protein concentration. However, the poor relationship between Iysine and crude protein concentration (r = .64 to . 73) of corn limits the utility of this application. In most practical situations, reformulating swine diets to account for higher protein content of low-test-weight corn is of limited value.
Keywords: feed, corn, lysine, protein
Cite as: Johnston LJ. Use of low-test-weight corn in swine diets and the lysine/protein relationship in corn. J Swine Health Prod 1995;3(4):161-164.
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