title: Effects of malate on diet digestibility, microbial protein synthesis, plasma metabolites, and performance of growing lambs fed a high-concentrate diet.
abstract: The objective of this study was to evaluate the effects of malate supplementation on growth rate, feed efficiency, and diet digestibility in growing lambs. Twenty-four Merino lambs with a mean BW of 15.3 +/- 0.22 kg were divided into 3 homogenous groups. Each group was randomly allocated to 1 of 3 malate (16% disodium malate:84% calcium malate) levels: 0 (control), 4 (MAL-4), or 8 (MAL-8) g/kg of concentrate. Lambs were fed concentrate and barley straw ad libitum for 35 d. After a 20-d period, diet digestibility was determined, and microbial N flow at the duodenum was estimated from the urinary excretion of purine derivatives. Blood samples were taken on d 0, 20, and 35. On d 35, lambs were slaughtered and ruminal fluid samples were collected. There were no effects (P = 0.18 to P = 0.95) of malate on concentrate or straw intake, ADG, carcass yield, and apparent digestibility of OM, CP, NDF, or ADF. Malate supplementation did not influence (P = 0.80) the daily urinary excretion of total purine derivatives, and therefore there were no treatment effects (P = 0.77) on estimated microbial N flow at the duodenum. No differences (P > 0.05) among treatments were observed for plasma concentrations of glucose, cholesterol, triglycerides, urea-N, lactate, or VFA, but malate addition increased (P = 0.003) the molar proportion of butyrate in ruminal fluid (4.29, 6.14, and 5.45% of total VFA for control, MAL-4 and MAL-8, respectively). The use of malate as a feed additive under the conditions of the current study did not influence diet intake or digestion, and consequently did not improve lamb performance.
authors.affiliation: Departamento de Producción Animal I, Universidad de León, 24071, Spain. dp1mct@unileon.es
authors.forename: M D
authors.initials: MD
authors.lastname: Carro
authors.forename: M J
authors.initials: MJ
authors.lastname: Ranilla
authors.forename: F J
authors.initials: FJ
authors.lastname: Giráldez
authors.forename: A R
authors.initials: AR
authors.lastname: Mantecón
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001774:Blood Chemical Analysis / Q000662:veterinary; D001835:Body Weight; D004032:Diet / Q000662:veterinary; D004063:Digestion / Q000187:drug effects*; D004386:Duodenum / Q000378:metabolism; D004435:Eating / Q000187:drug effects*; D006128:Growth / Q000187:drug effects; D001467:Hordeum / Q000378:metabolism; D008293:Malates / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D017672:Nitrogen Compounds / Q000652:urine; D011897:Random Allocation; D012417:Rumen / Q000737:chemistry; D012756:Sheep / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D008293:Malates; D017672:Nitrogen Compounds; C030298:malic acid