Citation of this paper

Effect of brewers’ grain as replacement of wheat bran on feed intake, growth performance, digestibility and nitrogen balance of sheep fed barley straw

Niguse Gebru Weldemariam

Adigrat University department of Animal Production and Technology, P O B. 50, Adigrat, Ethiopia
niguseg41@gmail.com

Abstract

An experiment was conducted to evaluate the effect of substitution of wheat bran by brewers’ grains on feed intake, growth performance, digestibility and nitrogen balance of sheep. Thirty sheep with initial body weight of 9.54 ± 1.12 kg were used for a 90 day feeding and 7-day digestibility trial. The intake and digestibility of DM , the retention of nitrogen, and the liveweight gain and feed conversion efficiency, were improved when the brewers’ grain replaced wheat bran.

Key words: byproduct, bypass protein, Ethiopia

Introduction

Ethiopia possesses a large number (30.7 million) of sheep (Central Statistics Authority 2017). But the productivity is low due to different problems, of which feed is the basic challenge. Wheat bran is a common supplemental feed in Ethiopia; but the cost is challenging. Thus, it is high time to find other cost effective and nutritional options that will improve performance and make better use of local feed resources. Brewery waste (brewers’ grains) is a cheap and nutritionally rich feed (Nicory et al 2015). Currently in Ethiopia, new breweries are being launched and are producing huge quantities of byproducts that are a challenge for the environment. It is suggested that these byproducts can play a significant role as animal feed and should be considered as one of the strategies to solve the feed scarcity with effective cost. Therefore, this study was aimed to evaluate the effect of dried brewers’ grain as replacement of wheat bran on feed intake, body weight change, digestibility and nitrogen balance of sheep fed barley straw.

Materials and methods

Study area

The study was conducted in Adigrat town, Tigrai Regional State having 500mm annual average rain fall and 13.9^OC average temperature. The altitude of the area is 2800 meters above sea level.

Animals, experimental design and diet

Thirty yearling male Tigrai highland sheep with mean body weight of 9.54 ± 1.12 kg were used for the experiment. The sheep were held in quarantine for 21 days, dewormed and vaccinated for ovine pasteurellosis. Animals were arranged on the basis of their initial body weight into six blocks of five animals in a randomized design. Animals from each block were randomly allocated to the five treatment groups (Table 1). There was an adaptation period of 15 days before data collection. Barley straw was used as a basal diet. Wheat bran was purchased from the local market. Brewers’ grains were purchased from Raya beer factory and sun-dried. The diets were offered twice per day at 0800 and 1600 hours. Water and mineral licks were offered free choice. Feed offered and corresponding refusals were recorded daily. At the end of the 90 days, daily refusal and offered samples were mixed for each animal and each feed, respectively and sub-sampled for further chemical analysis.

Table 1. Experimental treatments
	Barley straw	Supplements, g DM
	Barley straw	WB	BG

BG₀	Ad libitum	400	0
BG₁₀₀	Ad libitum	300	100
BG₂₀₀	Ad libitum	200	200
BG₃₀₀	Ad libitum	100	300
BG₄₀₀	Ad libitum	0	400
BG = Brewers’ grain; WB= Wheat bran

Feed intake and body weight change

The daily feed offered and refusals were weighed and recorded and sub-samples taken for proximal analysis. Body weight of the animals was taken at the beginning of the feeding trial after and every 15 days. Feed conversion efficiency (FCE) was calculated as ADG/DM intak e. At the end of the feeding trial, all the sheep were harnessed with bags to collect feces. After three days adjustment, feces were collected for seven consecutive days. Daily feed offered and refusal per sheep was recorded. The total fecal output was collected and sub-samples stored frozen at -20^oC and pooled over the collection period to be dried in an oven at 60⁰C for 72h.

Apparent digestibility was calculated as:

Nitrogen retention was calculated as the difference between total N intake and sum of fecal and urine nitrogen. The rates of nitrogen absorbed and retained were calculated by the following two formulae, respectively:

Chemical analysis

Samples of feed offered, refusals and feces were analyzed for DM, N and ash according to AOAC (1990). ADF, NDF and ADL were determined according to Van Soest et al (1991).

Table 2. Chemical composition of feeds
	BG₀	BG₁₀₀	BG₂₀₀	BG₃₀₀	BG₄₀₀	Straw

DM, %	90.6	91.3	91.8	91.9	93.0	94
% in DM
Ash	6.21	5.6	5	4.4	4.41	4.7
CP	17.1	19.5	22	23.6	25.2	3.1
EE	5	4.7	4.5	4.2	3.8	0.9
NDF	58.1	53.2	49.5	47.4	45.2	47.6
ADF	14.7	20	24.5	24.6	27.5	18.5
ADL	4.11	4.8	6.1	6.2	6.41	3.9
ADF= acid detergent fiber; ADL= acid detergent lignin; BG= brewer grain; CP= crude protein; DM=dry matter; EE = ether extract; NDF = neutral detergent fiber; NFC= non fiber carbohydrate; WB= wheat bran

Statistical analysis

Data were analyzed using the general linear model procedure of SAS (2002)version 9.1. The model was: Y_ij = µ + T_i + B _j +e_ij. Where: Y_ij = response variable; µ = overall mean; T_i = treatment effect; B _j = block effect; eij = random error.

Result and discussion

Chemical composition of feeds

Replacing wheat bran with brewers’ grains reduced the ash, ether extract and NDF and increased the crude protein, ADF and ADL (Table 2).

Feed intake, live weight change, digestibility and N retention

DM intake was not affected but live weight gain and feed efficiency were improved with curvilinear trends as wheat bran was replaced by brewers’ grains (Table 3; Figures 1 and 2). This almost certainly reflects the bypass protein characteristics known to be possessed by brewers’ grain (Promkot and Wanapat 2003; Silivong et al 2013). These improvements in growth performance are supported by related effects showing superior digestibility and 50% higher N retention with increasing levels of brewers’ grains replacing wheat bran (Table 4). The biological value of the protein (>87%) was high on all combinations of wheat bran and brewers’ grains (Table 4).

Table 3. Feed intake and growth performance of the sheep
	BG₀	BG₁₀₀	BG₂₀₀	BG₃₀₀	BG₄₀₀	SEM	p

DM intake, g/d
Straw	483^ab	478^b	495^ab	500^a	493^ab	27.6	0.049
Supplement	387	380	386	387	377	17.4	0.712
Total	871	858	881	893	871	35.0	0.347
Growth performance
Init wt, kg	9.37	9.38	9.37	9.47	9.47	0.59	0.991
Fin wt, kg	12.4^d	12.7^cd	13.2^c	14.0^b	15.5^a	0.66	<0.0001
ADG, g/d	34.2^d	37.4^d	43.5^c	50.6^b	67.9^a	5.05	<0.0001
FCE	0.039^d	0.044^cd	0.049^c	0.057^b	0.078^a	0.0059	<0.0001


Figure 1. Daily live weight gain of sheep according to level of BG in the diet	Figure 2. Feed conversion efficiency of sheep according to to level of BG in the diet.

Table 4. DM intake and apparent digestibility by sheep supplemented with wheat bran replaced by brewers’ grain
	BG₀	BG₁₀₀	BG₂₀₀	BG₃₀₀	BG₄₀₀	LSD	SEM	p

Intake, g/d
DM	578	606^bc	632^ab	637^ab	655^a	40.64	1168.27	0.0058
CP	56.4^e	60.^d	73.4^c	80.7^b	85.6^a	3.87	10.60	<.0001
NDF	214^d	300^c	371^b	385^ab	391^a	15.4	167.75	<.0001
ADF	100^c	109^cb	115^abc	132^ab	134^a	358	22.51	0.0175
Coefficient of apparent digestibility
DM	0.66^c	0.71^b	0.72^b	0.71^b	0.75^a	0.0327	0.00076	0.0003
OM	0.67^c	0.71^b	0.72^ab	0.72^ab	0.75^a	0.00083	0.0343	0.0006
CP	0.69^d	0.68^d	0.73^c	0.75^b	0.77^a	0.0202	0.00029	<.0001
NDF	0.54^d	0.69^c	0.75^b	0.77^a	0.77^ab	0.0195	0.00027	<.0001
ADF	0.68	0.67	0.62	0.69	0.69	0.1129	0.00901	0.6257
^a,b,c = Means with different superscripts in the row are different at p<0.05; ADF = acid detergent fiber; CP = crude protein; DM = dry matter; NDF = neutral detergent fiber; OM= organic matter; SEM = standard error of mean

Table 5. Nitrogen balance of sheep supplemented with wheat bran replaced by brewers’ grain
	BG₀	BG₁₀₀	BG₂₀₀	BG₃₀₀	BG₄₀₀	LSD	SEM	p

N balance, g/d
Intake	12.99^d	14.25^c	16.05^b	17.15^a	17.69^a	0.632	0.2821	<.0001
Feces	3.96^c	4.52^a	4.30^ab	4.23^abc	3.99^bc	0.329	0.0765	<0.01
Urine	1.12^b	1.13^b	1.45^a	1.55^a	1.54^a	0.213	0.0322	<0.0001
Retention	7.91^d	8.59^d	10.29^c	11.37^b	12.16^a	0.695	0.3419	<.0001
Ret., % digested.	87.7	88.3	87.6	88.0	87.7	1.03	2.54	<0.051
^a,b,c,d = Means with different superscripts in the row are different at p<0.05

Figure 3. Effect of level of brewers’ grains in the diet on N retention in sheep

Conclusion

The intake and digestibility of DM , the retention of nitrogen, and the liveweight gain and feed conversion efficiency were improved when brewers’ grain replaced wheat bran as supplement to wheat straw fed to sheep

Acknowledgements

The author would like to acknowledge Adigrat University for financial support by the grant No AGU/CAES/033/08 and access to the necessary facilities.

References

AOAC 1990 Association of Official Analytical Chemists, Official Methods of Analysis, 15th Edition ed. Washington, DC.

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Received 8 November 2019; Accepted 16 November 2019; Published 2 January 2020

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