ASSESSMENT ON THE PRODUCTION, CONSERVATION AND UTILIZATION PRACTICES OF BREWERY SPENT GRAIN ACROSS SELECTED DESTRICTS IN ETHIOPIA, AND ITS SUPPLEMENTARY VALUE FOR DAIRY COWS
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Date
2019-08
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Abstract
he survey study was aimed at assessing the production; conservation practices and
utilization patterns of brewers’ grain from across selected dairy farms and all beer
factories in the country. The household survey was conducted in three selected
districts of which Sebeta and Bedele districts are located in Oromia regional state
while Debre-Berhan district is located in Amhara regional state. A total of 195
randomly selected household respondents were involved in the study. Key informants
working in each beer factory and survey locations in the country were also
considered for the study. Household respondent and key informant interview were the
kind of survey methodologies employed to conduct the field study. Data from the
household based survey was collected using a pre-tested fully structured checklist.
The result showed that brewery spent grain also called brewer’s grain (BSG) and
brewer’s spent yeast (BSY) were the major byproduct feeds produced by all beer
factories in Ethiopia. There were in total 12 factories producing an estimated
26722.8 tons BSG (DM basis) and 360,758.1 hectoliters (hl) of BSY in 2016 G.C.
Roughage feeds consumed by a lactating crossbred cow was estimated at 3.5 kg, d-1,
with higher intake (P<0.05) recorded for cows in Sebeta district. Similarly, daily
concentrate, BSG, mineral salt, and total DM intakes were also found to be higher
(p<0.05) for lactating cows in the Sebeta district. According to the view of the
respondents, heavy reliance and long term feeding of BSG could bring about feedrelated
metabolic, productive and reproductive problems in dairy cattle. These were:
reproductive and metabolic disorders, and blindness in newly born calves. Moreover,
a third of all household respondents across the studied districts claimed to have
observed milk with less fat yield (P<0.05). Soaking of salt treated fresh BSG in cold
water, sun drying and ensiling in that order of importance were the most commonly
used local BSG conservational practices and showed great variation (P<0.05) across
the surveyed districts. Some 77.3% and 61.4% of smallholder dairy farms in the
Sebeta and Debre Birhan districts had better access to BSG supply compared to
farms in the Bedele district (P<0.05). Contrary to this, the factory gate price per quintal of dried BSG was much cheaper for farmers in Bedele, medium and costly for
farmers in Debre Birhan and Sebeta districts, respectively (P<0.05). On the other
hand, the study also had two lab-based studies aimed at investigating the effects of
aerobic and anaerobic conservation practices on nutritional compositions and fungal
load dynamics of fresh and BSG samples conserved according to local storage
practices. Accordingly, in the first 3X3 factorial experiment, an attempt was made to
determine an optimum storage durations for fresh BSG samples conserved under
varying aerobic storage duration and temperature conditions. Thus, under local
conditions, it would be safe to store and feed fresh BSG provided that it is stored for
less than 6 and 2 days at 15°C and 20°C, respectively (P<0.05) without being
exposed to aerobic deteriorations. In a second lab-based trial where local
conservation practices identified from the survey study have been evaluated for their
major proximate compositions, digestible organic matter in the dry matter (DOMD),
in-situ crude protein (CP) and dry matter (DM) degradability characteristics, and
fungal load dynamics using the model for a completely randomized design. The
ensiling technique outperformed (P<0.05) the remaining local conservation practices
of soaking and sun drying techniques. Lastly, an in-vivo trial was conducted using
eight early lactating crossbred cows (50% BXF) with a major objective to identify
and recommend optimum level of ensiled BSG that iso-nitrogeneously replaced
increasing levels of cottonseed cake (0, 33, 66 & 100%) from on-station used dairy
formula feed. A 4X4 Double Latin Square design was used to analyze the data set
generated from the feeding and digestibility trials. It has been observed that ensiled
BSG has fully (100%) replaced cottonseed cake from the dairy formula feed
substantially improving (P<0.05) total ration’s apparent digestibility for DM, CP,
neutral detergent fiber (NDF) and acid detergent fiber (ADF), daily milk yield and
milk production efficiency. However, associated to lower estimated metabolizable
energy (EME) intakes, heavy reliance on BSG based diet should be balanced for
dietary energy rich feedstuffs and roughage sources rich in short and medium chain
fatty acids to avoid sustained body weight loss, lower milk fat, and total solids.
Description
PhD Thesis
Keywords
apparent digestibility, brewery spent grain, fungal