title: Physiological changes in rumen fermentation during acidosis induction and its control using a multivalent polyclonal antibody preparation in heifers.
abstract: Physiological changes in rumen fermentation during acidosis induction and its control using a multivalent polyclonal antibody preparation (PAP) were studied in a completely randomized experiment using 12 crossbred heifers (452 +/- 20 kg of BW). Treatments were control (CTR) or PAP. The acidosis induction protocol consisted of 3 periods: 3 mo of 100% fescue hay fed for ad libitum intake, 10 d (from d 1 to 10 of the experiment) of adaptation to the treatment (100% forage feeding + 10 mL/d of PAP top-dressed to the treatment group), and 5 d (from d 11 to 15 of the experiment) of transition, which consisted of increasing the concentrate (16.5% CP) 2.5 kg/d up to 12.5 kg/d while maintaining ad libitum intake of fescue and providing 10 mL/d of PAP to the treated heifers. Concentrate feeding of 12.5 kg/d was maintained until heifers developed acidosis (from d 16 to 22 of the experiment). When an animal was considered acidotic, it was changed to a 50:50 forage:concentrate diet, monitored for 4 d, and removed from the experiment. Samples of ruminal fluid were collected before and 6 h after feeding to determine pH, VFA, lactate, protozoa counts, and DNA extraction for quantitative real-time PCR and denaturing gradient gel electrophoresis analyses. Only samples collected during adaptation to the treatment, at 3 and 1 d before acidosis, on the acidosis day, and at 1 and 4 d after acidosis were analyzed. Differences were declared at P < 0.05. Heifers (83% for CTR, and 50% for PAP) entered into acidosis 5.25 +/- 0.17 d after the beginning of the transition. The fermentation profile of animals with acidosis was similar between treatments. From 3 d before acidosis to acidosis day, decreases in pH and in acetate-to-propionate ratio and increases in total VFA, butyrate, and entodiniomorph counts were observed. However, the greatest concentrations of Streptococcus bovis and Megasphaera elsdenii (79 +/- 54 and 104 +/- 73 ng of DNA/mL of ruminal fluid, respectively) and a decrease in DMI (10.6 vs. 6.46 kg, respectively) were recorded 1 d after acidosis. Compared with CTR heifers, heifers fed PAP had greater pH before feeding on d 6 (6.70 vs. 6.11), 8 (6.54 vs. 5.95), and 9 (7.26 vs. 6.59) after the beginning of the feeding challenge. Heifers fed PAP tended to have greater total VFA concentrations than CTR (124 and 114 +/- 4.0 mM, respectively). These results indicate that PAP may be effective in controlling acidosis of heifers during a rapid transition to a high-concentrate diet.
authors.affiliation: Grup de Recerca en Nutrició, Maneig i Benestar Animal, Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, 08193-Bellaterra, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Blanch
authors.forename: S
authors.initials: S
authors.lastname: Calsamiglia
authors.forename: N
authors.initials: N
authors.lastname: DiLorenzo
authors.forename: A
authors.initials: A
authors.lastname: DiCostanzo
authors.forename: S
authors.initials: S
authors.lastname: Muetzel
authors.forename: R J
authors.initials: RJ
authors.lastname: Wallace
mesh_terms: D000138:Acidosis / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D000818:Animals; D000907:Antibodies, Bacterial / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D001419:Bacteria / Q000187:drug effects; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000382:microbiology; D016000:Cluster Analysis; D056890:Eukaryota / Q000187:drug effects / Q000302:isolation & purification; D005260:Female; D005285:Fermentation / Q000187:drug effects; D005766:Gastrointestinal Contents / Q000737:chemistry / Q000382:microbiology / Q000469:parasitology; D006863:Hydrogen-Ion Concentration; D011897:Random Allocation; D012417:Rumen / Q000378:metabolism* / Q000382:microbiology / Q000469:parasitology
chemical_list: D000907:Antibodies, Bacterial