title: Hulled and hull-less barley grains with the genetic trait for low-phytic acid increased the apparent total-tract digestibility of phosphorus and calcium in diets for young swine.
abstract: A 35-d experiment was conducted using 63 crossbred pigs (35 barrows and 28 gilts) with an initial average BW of 7.0 kg and age of 28 d to evaluate the efficacy of the low-phytic acid (LPA) genetic trait in hulled or hull-less barley in isocaloric diets. Hulled barleys were the normal barley (NB) cultivar Harrington and the near-isogenic LPA mutant 955 (M955) with P availabilities of 36 and 95%, respectively. Hull-less lines were produced by crossing NB and the LPA mutant 422 line with a hull-less line, producing hull-less NB (HNB) and hull-less mutant 422 (HM422) with P availabilities of 41 and 66%, respectively. Pigs were in individual metabolism cages or pens for Phase 1 (d 0 to 14) and Phase 2 (d 14 to 35). Diets defined as NB, HNB, HM422, or M955 with no added inorganic P (iP) had available P (aP) concentrations of 0.27, 0.28, 0.35, and 0.40% for Phase 1 and 0.15, 0.17, 0.23, and 0.31% for Phase 2, respectively. Only diet M955 was adequate in aP. Therefore, iP was added to the P-deficient diets to make diets NB + iP, HNB + iP, and HM422 + iP with aP equal to that in diet M955. Overall (d 0 to 35), ADG and G:F were greater ( < 0.01) for pigs fed diet M955 or the diets with added iP than for pigs fed the NB diet. Serum tartrate-resistant acid phosphatase activity on d 34 was greater ( < 0.01) for pigs fed the NB or HNB diets than for pigs fed the other diets. Bone breaking strength and P absorption (g/d) were greater ( < 0.01) for pigs fed diet M955 or the diets with iP than for pigs fed the NB or HNB diets. Pigs fed diet M955 absorbed greater ( < 0.01) percentages of P and Ca and had less ( < 0.01) fecal excretion of P (g/d and %) and Ca (%) than pigs fed the other diets. In conclusion, the LPA genetic trait was effective in hulled and hull-less barley in isocaloric diets fed to young pigs. Pigs fed the diet with LPA M955 consumed 31% less P and excreted 78% less fecal P and 30% less fecal Ca than pigs fed the diet with NB + iP that was equal to diet M955 in aP. Therefore, LPA barley, especially M955 with 95% aP, will reduce the use of iP in swine diets, reduce P pollution from swine manure, and support the goal of achieving global P sustainability.
authors.forename: T L
authors.initials: TL
authors.lastname: Veum
authors.forename: V
authors.initials: V
authors.lastname: Raboy
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002136:Calcium, Dietary / Q000378:metabolism; D004032:Diet / Q000662:veterinary*; D005260:Female; D041981:Gastrointestinal Tract / Q000378:metabolism; D001467:Hordeum / Q000737:chemistry*; D008297:Male; D010758:Phosphorus / Q000378:metabolism; D016226:Phosphorus, Dietary / Q000378:metabolism; D010833:Phytic Acid / Q000378:metabolism*; D013552:Swine / Q000502:physiology*
chemical_list: D002136:Calcium, Dietary; D016226:Phosphorus, Dietary; D010758:Phosphorus; D010833:Phytic Acid; D002118:Calcium