Use of exogenous fibrolytic enzymes to improve the nutritive value of preserved forage for ruminants

This study was conducted to determine the effects of fibrolytic enzymes applied at baling, with or without ferulic acid esterase (FAE) producing bacterial inoculant, or to hay at feeding on digestibility and growth performance of lambs. Prior to starting the animal studies, two runs of replicated 24- and 48-h batch culture in vitro incubations were conducted using control alfalfa hay to select a suitable enzyme and dose. Eleven replicate bales of alfalfa-grass (93.8:6.2) hay (~500 kg) were produced with the application of one of three treatments: control (water), enzyme applied at baling (Eb; Econase RDE-L, AB Vista, Wiltshire, UK) and enzyme plus ferulic acid esterase producing bacterial additive applied at baling (EIb; 11 GFT, Pioneer HI-Bred Ltd., Chathan, ON, Canada). The mean internal bale temperature after 50 days of storage was greater (P<0.001) for Eb than control and EIb, as was the post-storage hemicellulose (P<0.05) concentration [mean bale temperature (°C), Eb = 26.8, EIb = 22.8, control = 17.8; hemicellulose concentration (g/kg dry matter), Eb = 127, control = 115, EIb = 114]. Two animal experiments using lambs were conducted after bales were stored for at least 90 days. The digestibility study was a replicated 4 × 4 Latin square design with 16 lambs and the animal performance study consisted of 32 lambs (8 per treatment) in a randomized complete block design. In both studies lambs received one of four treatments: control, Eb, EIb and enzymes added to control hay at feeding (Ef). In the digestibility study, total tract apparent organic matter (OM) (P=0.07) digestibility tended to be affected by treatment, with OM digestibilities greater for lambs fed Ef compared with lambs fed the other treatments, although differences were small (Ef vs. others; OM, 0.658 vs. 0.646). However, neutral detergent fiber (aNDF) and hemicellulose digestibilities were greatest (P<0.05) for lambs fed Eb, with no differences among the other treatments (aNDF, Eb = 0.480, control = 0.437, Ef = 0.430, EIb = 0.430; hemicellulose, Eb = 0.524, control = 0.460, Ef = 0.458, EIb = 0.446). In both studies there was no effect (P>0.05) of treatment on OM intakes. Average daily gain (ADG, g/d) of lambs in the performance study was greater (P=0.048) for EIb (233) than control (192) and Ef (202), and intermediate for Eb (206). Feed efficiency tended to be affected (P=0.07) by treatment; gain:feed for EIb was 18% greater than control and Eb and Ef were similar to the control. This study showed that applying enzymes to alfalfa hay at baling decreased aerobic stability, and increased fiber content and its digestibility, but ADG and gain:feed of lambs were not improved. Adding FAE producing bacterial inoculant with enzymes at baling improved aerobic stability of hay and ADG and gain:feed of lambs were increased relative to lambs fed control and enzymes applied at feeding. Applying enzymes at feeding increased apparent OM digestibilities but not fiber digestibilities, and had no effect on animal performance. We conclude that fibrolytic enzyme application with FAE producing bacterial inoculant at baling was the most promising method for enhancing performance of lambs fed baled alfalfa hay