Effects of supplementation with fibrolytic enzymes in dairy goats

Eliel González García

ABSTRACT
Twenty-four multiparous Murciano-Granadina dairy goats in mid lactation (weeks 13 to 26) were used in a single cross-over design to evaluate the effect of supplementation with an exogenous fibrolytic enzyme complex (Promote®) on feed intake, milk yield and composition, live-weight and body condition score change. At the end of lactation trial, eight goats (four per treatment) were selected to measure the total tract digestibility from week 27 to 30 of lactation. Degradability of DM and NDF, as well as gas production, were also studied under in vitro conditions. Goats received an ad libitum total mixed ration composed of 65% forage (dehydrated mixture of 50% alfalfa and 50% maize-whole plant) and 35% concentrate to which the enzyme was added. Treatments were according to concentrate: Control (C; without enzyme) and Enzyme (E; Promote®, included at 0.47 % in the concentrate). Feed intake (2.02 kg DM/d), milk yield (1.51 l/d), 4% ECM (1.80 l/d), and milk composition (TS, 13.9%; fat, 5.25%; CP, 3.75%; true protein, 3.54%) were not affected by enzyme supplementation, although CN tended to decrease in Enzyme treatment (Control, 2.87%; Enzyme, 2.81%; P< 0.09). Body weight change (Control, -0.1 kg; Enzyme, +1.90 kg; P< 0.10) and body condition score change (Control, +0.09; Enzyme, +0.19; P<0.14) tended to be higher with enzyme treatment. Digestibilities of DM (Control, 68.9%; Enzyme, 71.9%) and OM (Control, 70.4%; Enzyme, 72.9%) were higher (P<0.05) with enzyme supplementation, CF digestibility tended to decrease (Control, 41.9%; Enzyme, 37.6%; P<0.14), while those of CP (61.9%), NDF (54.3%) and ADF (48.8%) were not affected with the enzyme addition. Total tract digestibility results could not be supported by the in vitro trial on which similar effects were observed both for degradability (DM, 51.8%; NDF, 37.7%) and gas production (143 ml/gDM) at 48h. Supplementing dairy goat diets with Promote®, under the conditions of this trial, did not affect lactation performance but enhanced DM and OM digestibility.