a spray-dried polyclonalantibody preparationon ruminal fermentationpatterns and digestibilityof cows fed highconcentrate diets

摘要

The present study aimed to evaluate theeffects of different doses of a spray-dried polyclonalantibody preparation against specificruminal bacteria on rumen fermentationparameters as well as protozoa counts, in situdegradability of sugarcane neutral detergentfibre (NDF) and total tract apparent digestibilityof total diet in cows fed high concentratediets. Eight ruminally-cannulated cows wereused in a replicated 4-4 Latin square designwith four experimental periods of 21 days. Thetreatments were: T1 (control), 0.0 g/d of multivalentpolyclonal antibody preparation (PAPMV);T2, 1.5 g/d of PAP-MV; T3, 3.0 g/d of PAPMV;T4, 4.5 g/d of PAP-MV. Sample collectionfor rumen fermentation parameters was carriedout the last day of each period at 0, 2, 4, 6,8, 10 and 12 h after morning meal. For protozoacounts, samples were collected the last dayof each period at 0 and 4 h after feeding. Insitu degradability of sugarcane NDF was performedthe last 5 days of each period, while total tract apparent digestibility of total dietwas assessed the last 10 days of each period.Regardless of sampling time, there was no linearor quadratic effect on rumen pH, total concentrationof short chain fatty acids, molarproportion of acetate, propionate and butyrate,ammonia nitrogen (NH3-N) or lactate. Notreatment effects were detected for protozoacounts, in situ degradability of sugarcane NDFand total tract apparent digestibility of totaldiet. In conclusion, different levels of spraydriedPAP-MV were not sufficient to alterrumen environment.