IS STARCH AN ESSENTIAL NUTRIENT FOR GROWING PIGS?
ZENG, XIAN JIAN
Distiller’s dried grains with solubles (DDGS), a co-product of the ethanol industry, are widely used in the swine industry, partially to replace soybean meal as well as parent grain and phosphorus. The main difference between DDGS and the parent grain is the low starch content of the DDGS, which was converted to ethanol during fermentation. Diets formulated with high DDGS will therefore have reduced starch content. The overall objective of this experiment was to determine if low dietary starch impacts efficient meat production in growing pigs. Six diets, consisting of five semi-purified iso-nitrogenous and iso-caloric diets with increasing starch content (0.0, 5.5, 11.0, 16.5 and 22.0%) and one commercial reference diet were fed to growing pigs for 26 days. Diets were maintained iso-caloric with canola oil. Four blocks of 12 gilts (28±2 days, 9.8±0.2 kg) were randomly assigned within block to one of the six treatments. Two additional pigs from each block were slaughtered on d 0 for baseline carcass measurements. Pigs were fed ad libitum. Body weight and feed intake were recorded on d 0, 7, 14, 19 and 26. Fecal samples were collected on d 17 and 18. A catheter was inserted into the jugular of 4 pigs per treatment on d 20. Blood samples were taken at: -15, 0 (feeding), 15, 30, 45, 60, 90, 120, 150, 180, 240, 300, 360, 420 and 480 min on d 24. Pigs were euthanized on d 26 and carcass composition determined. Average daily gain and feed intake improved as starch content increased (P<0.05) while feed efficiency was similar (P>0.1) among treatments. Apparent gross energy and dry matter digestibility improved linearly and apparent ether extract digestibility decreased linearly with increasing starch (P<0.01). Apparent crude protein digestibility was not affected as the content of dietary starch content increased (P>0.1). C-peptide (pro-insulin) increased (P<0.01) with increasing starch level. Blood glucose and blood urea nitrogen (BUN) were not affected by increasing starch concentration. Carcass crude protein, lipid, moisture, and ash accretion increased with increasing dietary starch level (P<0.05). The efficiency of protein gain (crude protein accretion to energy intake ratio) tended to increase with increasing starch content (P=0.07). Crude protein utilization (crude protein accretion to crude protein intake ratio) increased with increasing starch level (P<0.05). In summary, carcass crude protein accretion improved in response to the increasing starch content from the diet. In conclusion, starch isn’t an essential nutrient for growing pigs but it does require level of dietary starch for optimal protein deposition. This implies that maximizing the inclusion of DDGS or other low starch co-products in swine diets may require a consideration of the starch content of the diet to maintain optimal protein deposition.
DegreeMaster of Science (M.Sc.)
DepartmentAnimal and Poultry Science
CommitteeSchmutz, Sheila; Scott, Tom; Drew, Murray; Gabert, Vince
Copyright DateAugust 2012
Swine, Starch, DDGS, C-peptide, BUN, protein deposition