title: Malic acid or orthophosphoric acid-heat treatments for protecting sunflower (Helianthus annuus) meal proteins against ruminal degradation and increasing intestinal amino acid supply.
abstract: The protection of sunflower meal (SFM) proteins by treatments with solutions of malic acid (1 M) or orthophosphoric acid (0.67 M) and heat was studied in a 3 × 3 Latin-square design using three diets and three rumen and duodenum cannulated wethers. Acid solutions were applied to SFM at a rate of 400 ml/kg under continuous mixing. Subsequently, treated meals were dried in an oven at 150°C for 6 h. Diets (ingested at 75 g/kg BW0.75) were isoproteic and included 40% Italian ryegrass hay and 60% concentrate. The ratio of untreated to treated SFM in the concentrate was 100 : 0 in the control diet and around 40 : 60 in diets including acid-treated meals. The use of acid-treated meals did not alter either ruminal fermentation or composition of rumen contents and led to moderate reductions of the rumen outflow rates of untreated SFM particles, whereas it did not affect their comminution and mixing rate. In situ effective estimates of by-pass (BP) and its intestinal effective digestibility (IED) of dry matter (DM), CP and amino acids (AAs) were obtained considering both rates and correcting the particle microbial contamination in the rumen using 15N infusion techniques. Estimates of BP and IED decreased applying microbial correction, but these variations were low in agreement with the small contamination level. Protective treatments increased on average the BP of DM (48.5%) and CP (267%), mainly decreasing both the soluble fraction and the degradation rate but also increasing the undegradable fraction, which was higher using orthophosphoric acid. Protective treatments increased the IED of DM (108%) and CP, but this increase was lower using orthophosphoric acid (11.8%) than malic acid (20.7%). Concentrations of AA were similar among all meals, except for a reduction in lysine concentrations using malic acid (16.3%) or orthophosphoric acid (20.5%). Protective treatments also increased on average the BP of all AA, as well as the IED of most of them. Evidence of higher increases for those AA showing a high resistance to degradation in the untreated meal were also observed. The total supply of metabolisable AA was increased by 3.87 times for sulphur-containing AA, whereas that of lysine was increased by 2.5 times, mainly because of lysine losses with heat treatments. These treatments and especially that with malic acid would be useful to increase the protein value of these meals but their combined use with lysine-rich protein concentrates would improve the metabolisable protein profile.
authors.affiliation: Departamento de Producción Animal, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain. josemaria.arroyo.martinez@alumnos.upm.es
authors.forename: J M
authors.initials: JM
authors.lastname: Arroyo
authors.forename: J
authors.initials: J
authors.lastname: González
authors.forename: M
authors.initials: M
authors.lastname: Ouarti
authors.forename: J M
authors.initials: JM
authors.lastname: Silván
authors.forename: M L
authors.initials: ML
authors.lastname: Ruiz del Castillo
authors.forename: F
authors.initials: F
authors.lastname: de la Peña Moreno
mesh_terms: D000596:Amino Acids / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena / Q000187:drug effects; D000818:Animals; D004044:Dietary Proteins / Q000008:administration & dosage*; D005285:Fermentation / Q000187:drug effects; D005766:Gastrointestinal Contents / Q000737:chemistry / Q000187:drug effects; D006368:Helianthus / Q000737:chemistry*; D006358:Hot Temperature; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000187:drug effects; D008293:Malates / Q000494:pharmacology; D008297:Male; D010756:Phosphoric Acids / Q000494:pharmacology; D010940:Plant Proteins / Q000008:administration & dosage / Q000737:chemistry*; D011489:Protein Denaturation; D012417:Rumen / Q000187:drug effects / Q000378:metabolism; D034561:Sheep, Domestic / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins; D008293:Malates; D010756:Phosphoric Acids; D010940:Plant Proteins; C030298:malic acid; C030242:phosphoric acid