title: Tryptophan needs of lactating sows fed diets supplemented with crystalline lysine.
abstract: Large White x Landrace primiparous and multiparous sows (n = 115) were used to evaluate the tryptophan needs of lactating sows fed diets supplemented with crystalline lysine to contain .75% lysine. Sows were fed 1.8 kg of their allotted diets from d 110 of gestation until parturition and then were allowed ad libitum access to diets analyzed to contain either .12 (n = 58) or .17% (n = 57) tryptophan during a 21-d lactation. Diets were created by crystalline tryptophan and lysine additions to a corn-soybean meal basal diet that contained .12% tryptophan. Tryptophan level in the lactation diet did not affect number or weight of pigs at 21 d (P > .10). Sows fed .17% tryptophan were heavier at d 21 of lactation than those fed .12% tryptophan (P = .09) due to less weight loss during the 21-d lactation (P = .09). Feed intake was greater (P < .05) for sows fed .17% tryptophan than for sows fed .12% tryptophan. A reference diet analyzed to contain .11% tryptophan and .63% lysine was fed to an additional 11 sows only as a baseline for measuring plasma urea nitrogen and amino acids. Plasma tryptophan concentrations were higher (P < .05) for sows fed .17% tryptophan than for sows not fed added L-tryptophan. Among sows fed the low-tryptophan diets, sows fed the reference diet (.60% lysine) had higher (P < .05) plasma phenylalanine and valine concentrations than sows fed .75% lysine. Diet did not affect plasma concentrations of any other essential amino acid (P > .10). Plasma urea N levels were lower (P = .11) for sows fed the diet supplemented with tryptophan. Lactating sows allowed ad libitum access to diets containing .75% lysine benefited from higher feed intake and lower weight loss when dietary tryptophan levels were increased from .12 to .17%.
authors.affiliation: Department of Animal and Range Sciences, South Dakota State University, Brookings 57007-0392, USA.
authors.forename: G W
authors.initials: GW
authors.lastname: Libal
authors.forename: D J
authors.initials: DJ
authors.lastname: Uttecht
authors.forename: C R
authors.initials: CR
authors.lastname: Hamilton
mesh_terms: D000601:Amino Acids, Essential / Q000097:blood; D000818:Animals; D003460:Crystallization; D004032:Diet / Q000662:veterinary*; D005260:Female; D005527:Food, Fortified; D007774:Lactation / Q000502:physiology*; D008098:Litter Size; D008239:Lysine / Q000008:administration & dosage / Q000494:pharmacology*; D013552:Swine / Q000097:blood / Q000502:physiology*; D013997:Time Factors; D014364:Tryptophan / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D014508:Urea / Q000097:blood; D015431:Weight Loss / Q000502:physiology
chemical_list: D000601:Amino Acids, Essential; D014364:Tryptophan; D014508:Urea; D008239:Lysine