ALKALINE TREATMENT OF BARLEY STRAW AND ITS EFFECT ON DIGESTIBILITY, RUMEN FERMENTATION, FEEDLOT CATTLE PERFORMANCE AND PROFITABILITY
Date
2019-09-19
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0002-7620-8399
Type
Thesis
Degree Level
Masters
Abstract
Micro-machine technology may provide cost-savings to feedlot producers, but they are unable to deliver limestone and salt into feedlot rations. Two experiments were conducted to evaluate the effectiveness of treating barley straw with calcium oxide to improve forage quality and provide a calcium source in wheat-based finishing diets. Additionally, the impact of removing calcium (limestone) and salt from supplements was examined. Barley straw was treated with 5% CaO and hydrated to 50% moisture, then stored for 60 h before feeding or sampling in the trials. The first experiment examined in vitro and in situ trial improvements in forage digestibility associated with CaO treatment of barley straw and compared it to barley and corn silage. CaO did not improve (P=0.99) the in vitro NDFD of barley straw but did increase (P<0.01) in vitro DMD from 48.4% to 55.8%, however it remained lower than barley and corn silage. CaO treatment also reduced NDF content of barley straw from 77.8% to 65.8%. In situ effective rumen degradability of CaO straw was also improved (P<0.01) but remained lower than both silages. Indigestible NDF (uNDF) content was reduced with CaO treatment (38.9%; P<0.01) and was lower than barley straw (51.5%), barley silage (59.9%), and corn silage (56.3%). The second experiment examined feeding CaO treated straw (CaOS) in wheat-based finishing diets, as compared to barley silage and barley straw. An apparent digestibility trial examined nutrient digestibility and rumen parameters in cannulated heifers fed wheat-based diets with barley silage, barley straw or CaOS as the forage source. Two diets utilized CaOS and examined the impact of removing calcium and salt from the mineral and vitamin supplement. The same diets were fed to steers for 115 d prior to slaughter. A treatment was used to evaluate treating straw with CaO immediately before feeding. Apparent nutrient digestibility (DM, OM, ADF, NDF, starch) was not impacted by treatment (P>0.05). Rumen parameters (VFA, NH3, protozoa, rumen microbial N, pH) were not affected by treatment, with the exception of maximum rumen pH being reduced (P<0.001) in diets containing CaOS. Sodium intake was reduced (P<0.05) in the CaOS diet containing no supplemental salt or calcium and fecal Na excretion tended to be reduced (P<0.1) as well. However, the reduced excretion was not sufficient to result in improved Na retention (P>0.05). In the second trial, ADG and feed efficiency did not differ between steers fed barley silage and CaOS-no NaCl diets or straw+CaO diets, and was higher than barley straw and CaOS (with salt) diets (P<0.01). Carcass and liver abscess scores did not differ among diets, with the exception of a tendency for increased dressing percentage when barley silage was included in the diet (P<0.1). Economic analysis determined that feeding CaOS with no supplemental calcium or salt in wheat-based finishing diets reduced feed costs and cost of gain, making it an economically viable replacement for silage.
Description
Keywords
calcium oxide, alkaline treatment, beef cattle, straw, feedlot, digestibility
Citation
Degree
Master of Science (M.Sc.)
Department
Animal and Poultry Science
Program
Animal Science