Practical swine grower rations should contain adequate levels of choline, particularly for heavyweight hogs. Research has shown that feeding pregnant sows supplemental choline generally increases numbers of pigs born and, in some experiments, pigs weaned. Vitamin B 12 is required for growth, hemoglobin and red blood cell formation. It is available in animal byproducts and commercial preparations. Plant products are deficient, and where rations are formulated based primarily on corn and soybean-oil meal, supplemental sources need to be supplied.
Folic acid is an essential B-vitamin for swine.
Green leafy plants are an excellent source. Bacteria in the pigs' lower gut also can synthesize folic acid, making feces a source of this vitamin. Confinement practices of raising hogs has reduced both of these vitamin sources so research now indicates supplemental sources of folic acid should be added to the feed. Recent research has shown a mild increase in pigs born when folic acid is added to sow rations. Table 3 lists clinical and sub-clinical symptoms of vitamin deficiencies.