Supplementary value of sun dry brewer spent yeast as a replacement of cotton seed cake in the diet of lactating crossbred cows: intake, digestibility, milk yield and quality

Geberemariyam T, Mulugeta W, Getu K, Mesfin D, Aemiro K, Bethlehem M, Molla S and Yohannse H

Ethiopian Institute of Agricultural Research, P O Box 2003, Addis Ababa, Ethiopia
geberemom@gmail.com

Abstract

This study was aimed to evaluate the effect of dry brewery spent yeast (DBSY) substitution with cotton seed cake (CSC) on the performances of lactating dairy cows. A total of four mid lactating high grade (3/4 X Fresian X Borena) dairy cows with milk yield (8.1 ± 0.61 kg/d) (avg. ± SE) and parity( one through four) were randomly assigned into one of the four treatments using a 4X4 Latin square design. The dietary treatments were: natural pasture hay adlibitum plus0.5 kg concentrate mixture per litre of milk/cow. Dry brewery spent yeast was substituted with CSC at the rate of 0, 33, 66, and 100%. Dry matter (DM), crude protein and acid detergent fibre intakes showed no significant variation (p>0.05) but, neutral detergent fibre intake showed significant variation (p<0.05). Body weight conditions of the cows were significantly affected (p<0.05). The DM and nutrient digestibility were not affected (p>0.05) in the diet. The milk protein and total solid yields, and milk production efficiency were significantly affected by the substitution level (p<0.05). The DBSY totally can replace CSC without any negative effects on the performance of lactating dairy cow.

Key words: dry brewery yeast, milk yield, milk composition

Introduction

Lack of animal feed and high price of both roughage and concentrate feeds are the major constraints of livestock production in the developing world (Blocks 2006, Seyoum et al 2018). The expansion of agro industries and its by-products are an alternative of feed resources (Seyoum et al 2018, Vastolo et al 2022). There is an expansion of beer factories and the annual production capacity of brewers’ spent yeast (BSY) in Ethiopia is more than 360,758 hectoliters (Kitaw et al 2018), but transport and spoilage problems of the brewery by products, and high cost of protein source feed are the main issues of dairy cattle production (Terefe 2022, Ahmad et al 2022, Terefe et al 2023a). Brewery spent yeast is containing more dead cells and the growth medium are sold as yeast cultures (Newbold and Rode 2006, Rakowska et al 2017) and it can be used in liquid or dried form to provide protein, vitamins, and minerals (Hertrampf et al 2000, Tacon and Metian 2009, Terefe et al 2023b), improve milk production, fat and total solids cow milk ( Desnoyers et al 2009, Wijerathna et al 2020), to improve feed efficiency and performance of animals (Schingoethe et al 2004, McAllister et al 2011), improve the nutritive value and in vitro rumen fermentation characteristics of the feed (Lunsin et al 2020, Terefe et al 2023a), alleviating disease(AlZahal et al 2014), increasing energy-corrected milk and milk fat yield (Poppy et al 2012), and improve animal health and output by altering the rumen microbiota and fermentation (Baker 2021).

The yeast-fermented with de-hulled rice as a protein source improves nutrient degradability and in vitro rumen fermentation (Totakul et al 2020). An in-vitro dry matter digestibility can be increased by adding liquid brewery spent yeast (up to 30%) to the cassava silage (Kamphayae et al 2017). The addition of craft yeast in animal diets is important to reduce the amount of methane generated by bovine and caprine rumen (Pszczolkowski et al 2016). Cherdthong et al (2018) documented that brewery spent yeast replaced with soybean meal in concentrate diets did not affect gas dynamics or rumen fermentation. Dry brewers spent yeast can replace corn meal without affecting intake and digestibility of the sheep (Oliveira et al 2016). Additionally, the brewers dried waste can be used as a replacement of concentrate feed (15-25%) and there was no significant difference in milk production and quality (Shah et al 2023). Therefore, this study was aimed to evaluate the effect sun dry brewer’s spent yeast replacement with cotton seed cake on major productive performances of lactating crossbred dairy cows.

Materials and methods

Description of study area

The experiment was carried out at Holetta agricultural research center (HARC) dairy barn facility. The centre is located 29 kilometres west of Addis Ababa, Ethiopia. The center is located at 9^o03’28.82” E latitude and 38^o30’17.59” E longitude and at an elevation of 2,400 m above sea level. The average annual rainfall for the area is 1144 mm, while the average daily temperature ranges from 6 to 21^oC.

Experimental feed preparation

Natural pasture hay was harvested at about 50% heading stage from HARC grazing land and sun dried for three to five days. The dry hay was baled and stored in a shade located at HARC dairy farm. The wheat bran, cotton seed cake and salt were purchased from feed processing plants located at Addis Ababa. Autolysed liquid brewer spent yeast (subjected to heating at a temperature above 80^oC) was obtained from a nearby Heineken brewery factory located at Addis Ababa, Ethiopia. The scullery was allowed to cool for 12 hours before it was mixed with water. The mixed material (17: 83, yeast and water, respectively) was kept in plastic buckets. The buckets were placed in a fixed place until the residues were settled at the bottom and the water accumulated on top of the bucket so that the BSY biomass can be easily recovered after 7 hours soaking. The brewery spent yeast residues were then allowed to dry in the sun for three consecutive days (Terefe et al 2023).

Management and experimental design

Four mid-lactating high-grade (3/4 Boran x Fresian) dairy cows were randomly blocked in a 4 x 4 Latin square design. The cows with more or less similar initial average milk yield (8.1 ± 0.61), days in milking (83.7±7.1) but that differ only in parities (one through four) were selected from the available dairy herd size on-station. All the cows were sprayed against external parasites and drenched with broad-spectrum anti-helminths (Albendazole 500 mg) prior to the start of the trial. The cows were individually stall-fed in a well-ventilated barn with concrete floor and appropriate drainage slope and gutters. The cows were allowed to drink water adlibitum and exercise out of doors for about 30 minutes every morning. Cows were offered natural pasture hay adlibitum with 20% contingency. The feeding trial lasted for 100 days. The experimental period consisted of 15 days of adaptation and 10 days of actual data collection periods. The body weight of experimental cows was measured fortnightly for two consecutive days before a fresh daily diet was offered to the cows. The ration was formulated to support daily milk production of mid lactating cows with 4% butterfat. All cows were fed the natural pasture hay adlibitum and 0.5 kg concentrate mixtures (CM) per litter of milk production. The CM feed was offered with equal portions at 5:00 am and 5:00 pm during the morning and evening milking time, respectively. The amount of feed offered and refusal was weighed every day before the cows were served with the new meal. Therefore, the dietary treatments were: adlibitum feeding of all cows with natural pasture hay basal diet plus supplementation of the cows with 0.5 kg CM per each liter of milk production and a concentrate mixtures for which the dry brewery spent yeast (DBSY) have been substituted with cotton seed cake at the rate of 0 (DBSY0), 33 (DBSY33), 66 (DBSY66), and 100% (DBSY100).

Feed chemical analysis

During the entire period of the experiment, representative samples for the actual feed offered and refused and faecal samples were taken periodically, oven 65⁰C to a constant weight and subjected to grinding at 1 mm screen sieve size. The samples were analyzed at Holeta agricultural research center animal nutrition research laboratory Feed and faecal samples were analyzed for N, DM, Ash (AOAC 2005), ADF, ADL, NDF (Van Soest et al 1991).

Dry matter and nutrient apparent digestibility

Apparent digestibility was determined by using a total faecal collection method. In each period, the faeces were collected for 5 consecutive days. The attendants were assigned to receive faeces into the buckets from the concrete floor washed with high pressure water every time the cows urinated. The faeces from each cow were thoroughly mixed and a sample of 1% was taken and placed in a polyethylene bag daily and stored in a deep freezer (-20⁰C) until it is being thawed and subjected to oven drying for DM determination and sample processing for analytical purposes. The samples were dried at 65⁰C for 72 hours and ground to pass through a 1-mm sieve size and stored in a sample bottle at room temperature until analysis (McDonald et al 2002).

Milk yield and composition

The cows were hand milked at 5:00 AM and 5:00 PM and daily milk yield was recorded by using graduated cylinders. Milk aliquot samples (100 ml) were taken from the morning and evening milking with sterile plastic containers for five consecutive days. The samples were then kept under refrigeration pending laboratory analysis. The milk fat, protein, lactose and total solids were analysed at HARC dairy processing laboratory by using lacto scan ultrasonic milk analyser (INDI, 2018).

Fat corrected milk yield (FCMY, kg/day) and milk production efficiency (MPE: FCMY /kg feed DM) were calculated as, FCMY (kg/day)= 0.4 x daily milk yield (kg/day) + 15 x fat yield (kg/day), while MPE (FCMY/kg feed DM intake) = mean daily fat corrected milk yield (litter)/ mean daily DM intake (kg) (McDonald et al 2002, NRC 2001).

Statistical data analysis

Data was subjected to analysis of variance using R software, version 4.1.1 (Shah 2013). Mean separations from all the trials were subjected to Duncan’s multiple Range Test analysis at p≤ 0.05. The models for the design is

Y_ijk= µ + +C _i+P_{j +}T _k +E_ijk,

Where, Yijk is the dependent variable (intake and feed and nutrient digestibility, milk yield and composition), μ: overall mean, C _i : cow effect (parity) (i=1-4), P_j: effect of period (j=1-4), Tk: effect of treatment (diet) (k=1-4), Eijk: experimental error

Results

Chemical composition of feeds

The chemical composition of natural pasture hay and feed ingredients is presented in Table (1). The NDF and ADF components were higher (68.6% and 31.0%) in hay and lower (2.82% and 0.09%) in sun dried brewery spent yeast (DBSY), respectively. The DBSY had the greater crude protein but lower fiber fractions (ADF and NDF) content than wheat bran feed ingredients. The DBSY had the higher CP (37.8%) value than cotton seed cake which is used as a commercial protein source in the formulation of compound feeds in Ethiopia.

Feed and nutrient intakes and live weight

Except for NDF intake the there was no significant (p>0.05) difference in dry matter and nutrient intakes. However, body weight conditions of the cows was significantly affected by DBSY (p<0.05) (Table 2).

Apparent dry matter and nutrient digestibility

The apparent DM and nutrient digestibility did not show significant (p>0.05) difference across all substitution levels of sun dry brewery spent yeast (DBSY). However, numerically higher digestibility coefficients were recorded for cows receiving DBSY based diets than cows in the control group (Table 3).

Milk production and composition

Daily milk yield of the cow was not significantly affected (p>0.05) by the dietary treatments but cows receiving the sun dried brewery spent yeast (DBSY) based diet observed to have produced numerically higher milk yield than cows fed on the cotton seed cake based diet (Table 4 and fig 1). The total milk and fat corrected milk yields tended to have also linearly responded (p>0.05) to levels of DBSY inclusion. Fat and lactose yield did not respond to dietary treatments but showed similar trend (p>0.05) as for total milk yield and fat corrected milk yield with different inclusion levels of DBSY. The protein and total solid yields, and milk production efficiency of the cows were recorded to be significantly higher (p<0.05) for cows receiving the DBSY at levels > 66% substitution levels . In line to this complete replacement of DBSY for CSC resulted in substantial improvement that amounts to a 13.54% in daily milk, 12.73 % in total solid and 22.73% in protein yields over the cows in the control group, respectively. The milk compositional fractions except total ash were not significantly affected (p>0.05) by the replacement of DBSY by CSC. Ash content of the milk was notably higher (p<0.05) for cows in the DBSY33 while total solid content of the milk was higher (p<0.05) for the cows receiving the DBSY based intervention diets than those cows maintained over the control based diet.

Figure 1. Effect of brewery yeast replacement with cotton seed on milk production

Discussion

Feeds composition and intakes

The acid detergent fibre (1.8%) and neutral detergent fiber (6.2%) in dry brewery spent yeast reported by Ciurescu et al (2021) did not agree with the current finding while it could somehow compared to that reported earlier by Terefe et al (2023a) and Yadessa et al (2023). The higher crude protein (45.6-74%) and ash (5.9-14%)contents in brewery spent yeast were reported by Mathias et al (2015), Vieira et al (2016), Jacob et al (2016) and Marson et al (2020). Similar to the current finding, DBSY has been reported to replace up to 100% corn meal without negative effects on feed intake of sheep (Oliveira et al 2016). In addition, brewery spent yeast supplementation for dairy cows, weaned beef steers and sheep rations to increase feed and nutrient intakes (Desnoyers et al 2009, Finck et al 2014, Navarrete 2022).

Dry matter and nutrient digestibility

In agreement to the present study, live yeast supplementation can help fiber-degrading bacteria and increase fiber digestibility in grazing animals (Sousa et al 2018). Yeast supplementation increased dry matter, crude protein , organic matter and fiber digestibility in beef cattle and sheep diets (Ghoneem and Mahmoud, 2014, Ding et al 2014, Oliveira et al 2016, Maamouri and Ben Salem 2021, Phesatcha et al 2021). However, supplementation of live yeast for dairy cows did not show a significant effect on performance, rumination time, or rumen pH (Ambriz-Vilchis et al 2017). The pre-digestion of oil palm fronds with white rot fungi improves rumen degradation but yeast or enzymes without supplementation did not show any change (Hassim et al 2012). Likewise, the result of the current finding conforms very well to the finding of Cherdthong et al (2018) , who reported that brewery spent yeast is a potential substitute for soybean meal without affecting in vitro dry matter and organic matter digestibility. Similarly, supplementing yeast (active and killed dried yeast) for beef heifers and dairy cows had no significant effect on apparent nutrient digestibility and microbial crude protein flow (Vyas et al 2014, Robinson et al 2016).

Milk yield and composition and live weight

In line with the current finding, supplementation of live yeast for dairy cows did not show a significant effect on their performance (Ambriz-Vilchis et al 2017). However, the dairy cows receiving yeast performed better milk yield throughout the lactation period (Desnoyers et al 2009). Liquid brewer's yeast supplementation can enhance the overall production of milk and its components, including protein, fat, and total solids in cow's milk (Poppy et al 2012, Dias et al 2018, Alaru 2019, Wijerathna et al 2020). The quality of sheep's and goat milk is improved by adding liquid brewer's yeast supplements(Stella et al 2007, Navarrete 2022). The prior trials with dairy cows, lambs, and weaned beef steers receiving the brewery yeast did not demonstrate an influence on the average body weight gain, which is in contrast to the current information (Finck et al 2014, Perdomo et al 2020, Perdomo et al 2020).

Conclusion

• Dry brewery spent yeast can totally replace cotton seed meal without any negative effects on intake, digestibility, body condition, milk production and composition of lactating dairy cows.
  
  
• The long-term effect of DBSY utilization on both productive and reproductive performance of dairy cows under local conditions need to be studied.

References

Ahmad N, Aranguiz A A, Vernooij A and Mohammed D 2022Potential use of liquid spent brewer's yeast for animal feed in Ethiopia (No 1392). Wageningen Livestock Research.

AlZahal O, Dionissopoulos L, Laarman A H, Walker N and McBride B W 2014 Active dry Saccharomyces cerevisiae can alleviate the effect of subacute ruminal acidosis in lactating dairy cows. Journal of Dairy Science, 97(12), 7751–7763.

Alaru P A O 2019Evaluation of appropriate storage conditions of liquid brewer’s yeast as feed supplement for lactating dairy cows and its effect on milk quality (Doctoral dissertation, Egerton University).

Ambriz-Vilchis V, Jessop N S, Fawcett R H, Webster M, Shaw D J, Walker Nand Macrae A I 2017 Effect of yeast supplementation on performance, rumination timeand rumen pH of dairy cows in commercial farm environments. Journal of Dairy Science, 100(7), 5449–5461 https://doiorg/103168/jds2016-12346.

AOAC 2005 Official Methods of Analysis, 18^thedn Association of Official Analytical Chemists, Arlington, Vrginia, USA.

Baker L M 2021 The effects of dietary yeast extracts on rumen microbiota and fermentation in a dual-flow continuous culture fermentation system. The University of Vermont and State Agricultural College.

Blocks C I P 2006 Improving Animal Productivity by Supplementary Feeding of Multinutrient Blocks, Controlling Internal Parasites and Enhancing Utilization of Alternate Feed Resources.

Ciurescu G, Dumitru M and Gheorghe A 2021 Use of brewer’s yeast in broiler feeds to replace corn gluten meal with or without probiotic additives. Archiva Zootechnica, 24(1), 66-83.

Cherdthong A, Suntara C and Khota W 2020Lactobacillus casei TH14 and additives could modulate the quality, gas kinetics and the in vitro digestibility of ensilaged rice straw. Journal of Animal Physiology and Animal Nutrition, 104(6), 1690-1703.

Desnoyers M, Giger-Reverdin S, Bertin G, Duvaux-Ponter Cand Sauvant D 2009 Meta-analysis of the influence of Saccharomyces cerevisiae supplementation on ruminal parameters and milk production of ruminants. Journal of Dairy Science, 92(4), 1620–1632.

Dias A L G, Freitas J A, Micai B, Azevedo R A, Greco L F and Santos J E P 2018 Effect of supplemental yeast culture and dietary starch content on rumen fermentation and digestion in dairy cows. Journal of Dairy Science, 101(1), 201–221.

Ding G, Chang Y, Zhou Z, Ren L and Meng Q 2014 Effect of Saccharomyces cerevisiae on rumen fermentation characteristics, nutrient degradation and cellulase activity of steers fed diets with different concentrate to forage ratios. World Journal of Agricultural Research, 2(6), 303–308.

Finck D N, Ribeiro F R B, Burdick N C, Parr S L, Carroll J A, Young T R and Johnson B J 2014 Yeast supplementation alters the performance and health status of receiving cattle. The Professional Animal Scientist, 30(3), 333-341.

Ghoneem W M A and Mahmoud A E M 2014 Effect of inactivated and dried yeast on productive performance of Barki lambs. Asian J Anim Vet Adv.

Hassim H A, Lourenço M, Goh Y M, Baars J J Pand Fievez V 2012 Rumen degradation of oil palm fronds is improved through pre-digestion with white rot fungi but not through supplementation with yeast or enzymes. Canadian Journal of Animal Science, 92(1), 79–87.

Hertrampf J W, Piedad-Pascual F and Piedad-Pascual F 2000Pulses Handbook on Ingredients for Aquaculture Feeds, 338–350.

LACTO SCAN INDI MILK ANALYZER LCD 2018 Display–4 lines x 16 characters Operation manual.

Lunsin Ratchataporn, Ruangyote Pilajun, Suban Foiklang and Julakorn Panatuk 2020 Nutritive Value and in Vitro Digestibility of Yeast-Fermented Corn Dust with Cassava Pulp Affected by Ensiling Time.

Inthapanya S, Preston T Rand others 2016Effect of brewers grains and rice distillers byproduct on methane production in an in vitro rumen fermentation using ensiled or fermented cassava root (Manihot esculenta, Cranz) as energy substrate. Livestock Research for Rural Development, 28(11).

Jacob F, Striegel L, Rychlik M, Hutzler M and Methner F J 2019 Yeast extract production using spent yeast from beer manufacture: influence of industrially applicable disruption methods on selected substance groups with biotechnological relevance. European Food Research and Technology, 245, 1169-1182.

Kamphayae S, Kumagai H, Angthong W, Narmseelee R and Bureenok S 2017 Effects of different ratios and storage periods of liquid brewers yeast mixed with cassava pulp on chemical composition, fermentation quality and in vitro ruminal fermentation. Asian-Australasian Journal of Animal Sciences, 30(4), 470.

Kitaw G, Tamir B, Assefa G and Animut G 2018Production, preservation and utilization patterns. Ethiopian Journal of Agricultural Sciences, 28(3), 1-17.

Maamouri O and Ben Salem M 2021 Effect of yeast culture feed supply on growth, ruminal pHand digestibility of fattening calves. Food Science and Nutrition, 9(5), 2762–2767.

Marson G V, Saturno R P, Comunian T A, Consoli, L, da Costa Machado M T and Hubinger M D 2020 Maillard conjugates from spent brewer’s yeast by-product as an innovative encapsulating material. Food research international, 136, 109365.

Mathias T R D S, Alexandre V M F, Cammarota M C, de Mello P P M and Sérvulo E F C 2015 Characterization and determination of brewer's solid wastes composition. Journal of the Institute of Brewing, 121(3), 400-404.

McAllister T A, Beauchemin K A, Alazzeh A Y, Baah J, Teather R M and Stanford K 2011 The use of direct fed microbials to mitigate pathogens and enhance production in cattle. Canadian Journal of Animal Science, 91(2), 193-211.

McDonald P, Edwards R A, Greenhalgh J F D, Morgan C A, Sinclair L A and Wilkinson R G 2011 Animal Nutrition Essex Prentice Hall, Pearson.

Navarrete J 2022Evaluating the Influence of the Inclusion of Liquid Brewer’s Yeast during Gestation on Ewe and Lamb Performance, Colostrum and Milk Qualityand Transfer of Passive Immunity in Lambs (Doctoral dissertation, Illinois State University).

NRC 2001 Nutrient Requirements of Dairy Cattle Seventh Revised Edition , 2001, National Academy Press, Washington DC.

Newbold C J and Rode L M 2006 Dietary additives to control methanogenesis in the rumen. International Congress Series, 1293, 138–147.

Oliveira R L, Oliveira R J F, Bezerra L R, Nascimento T V C, de Pellegrini C B, de Freitas Neto M D, do Nascimento Júnior N G and de Souza W F 2016 Substitution of corn meal with dry brewers yeast in the diet of sheep. Revista Colombiana de Ciencias Pecuarias, 29(2), 99–107.

Perdomo M C, Marsola R S, Favoreto M G, Adesogan A, Staples C R and Santos J E P 2020 Effects of feeding live yeast at 2 dosages on performance and feeding behavior of dairy cows under heat stress. J Dairy Sci 103(1):325-339.

Phesatcha K, Phesatcha B, Wanapat M and Cherdthong A 2021 The effect of yeast and roughage concentrate ratio on ruminal pH and protozoal population in Thai Native beef cattle. Animals, 12(1), 53.

Poppy G D, Rabiee A R, Lean I J, Sanchez W K, Dorton K L and Morley P S 2012 A meta-analysis of the effects of feeding yeast culture produced by anaerobic fermentation of Saccharomyces cerevisiae on milk production of lactating dairy cows. Journal of Dairy Science, 95(10), 6027–6041.

Pszczolkowski V L, Bryant R W, Harlow B E, Aiken G E, Martin L J, Flythe M D and others 2016 Effects of spent craft brewers yeast on fermentation and methane production by rumen microorganisms. Advances in Microbiology, 6(09), 716.

Robinson P H, Erasmus L J and others 2016 Effects of two yeast based direct fed microbials on performance of high producing dairy cows. Animal Feed Science and Technology, 215, 58–72.

Schingoethe D J, Linke K N, Kalscheur K F, Hippen A R, Rennich D R and Yoon I 2004 Feed efficiency of mid-lactation dairy cows fed yeast culture during summer. Journal of Dairy Science, 87(12), 4178–4181.

Stella A V, Paratte R, Valnegri L, Cigalino G, Soncini G, Chevaux E, and Savoini G 2007 Effect of administration of live Saccharomyces cerevisiae on milk production, milk composition, blood metabolitesand faecal flora in early lactating dairy goats. Small Ruminant Research, 67(1), 7-13.

Seyoum B, Nemi G and Makkar H 2018Ethiopian Feed Industry: Current status, Challenges and opportunities, Feedipedia.

Shah B, Tiwari M R and Acharaya B 2023 Reviews Effect of Inclusion of Dried Brewers Waste in Basal Diet of Dairy Animals on Milk Production and its Parameter. International Journal of Research Publication 4(1), 265–269.

Shah N 2013 An Introduction to R Practical Graph Mining with R, 1, 27–52 https://doiorg/101201/b15352-7.

Sousa D O, Oliveira C A, Velasquez A V, Souza J M, Chevaux E, Mari L J and Silva L F P 2018 Live yeast supplementation improves rumen fibre degradation in cattle grazing tropical pastures throughout the year. Animal Feed Science and Technology, 236, 149–158.

Tacon Albert G J and Marc Metian 2009 Fishing for Feed or Fishing for Food: Increasing Global Competition for Small Pelagic Forage Fish. Ambio: 294–302.

Terefe Geberemariyam 2022 Preservation Techniques and Their Effect on Nutritional Values and Microbial Population of Brewers Spent Grain: A Review. CABI Agriculture and Bioscience 3(1): 1–8.

Terefe G, Walelgne M, Fekadu D, Kitaw G, Dejene M, Kehaliu A, Mekonnen B and Habteyesus Y 2023a Effect of sun dry brewer spent yeast on chemical composition, in vitro digestibilityand ruminal degradation kinetics of wheat straw. CABI Agriculture and Bioscience, 4(1), 1–8.

Terefe G, Kitaw G, Dejene M, Fekadu D, Kihalew A, Mekonnen B and Walelgne M 2023b Dairy farmer’s perception on feeding, conservation and constraints of brewery by-products utilization in selected districts of Ethiopia. Heliyon, 9(1).

Totakul P, Ampapon T, Foiklang S, Uriyapongson S, Sommai S, Matra M, Viennasay B and Wanapat M 2020 Effect of yeast-fermented de-hulled rice on in vitro gas production, nutrient degradabilityand rumen fermentation. Tropical Animal Health and Production, 52(6), 3567–3573 https://doiorg/101007/s11250-020-02393-5.

Van Soest P J van, Robertson J B and Lewis B A 1991 Methods for dietary fiber, neutral detergent fiberand nonstarch polysaccharides in relation to animal nutrition. Journal of Dairy Science, 74(10), 3583–3597.

Vastolo A, Calabrò S and Cutrignelli M I 2022A review on the use of agro-industrial CO-products in animals’ diets. Italian Journal of Animal Science, 21(1), 577-594.

Vieira E F, das Neves J, Vitorino R, Dias da Silva D, Carmo H and Ferreira I M 2016 Impact of in vitro gastrointestinal digestion and transepithelial transport on antioxidant and ACE-inhibitory activities of brewer’s spent yeast autolysate. Journal of agricultural and food chemistry, 64(39), 7335-7341.

Vyas D, Uwizeye A, Mohammed R, Yang W Z, Walker N D and Beauchemin K A 2014 The effects of active dried and killed dried yeast on subacute ruminal acidosis, ruminal fermentationand nutrient digestibility in beef heifers. Journal of Animal Science, 92(2), 724–732.

Wijerathna Jayantha, Lansakara Priyanwada, Abeysinghe Chandana and Prathapasinghe Gamika 2020 Supplementation of Brewer’s Yeast Slurry Improves the Performance of Dairy Cattle. World Journal of Biology Pharmacy and Health Sciences 1(1): 001–007.

Yadessa E, Tamir B, Kitaw G, Dejene M and Terefe G 2023 Effects of brewer's spent yeast inclusion level and ensiling duration on fermentative, fungal load dynamics and nutritional characteristics of brewer's spent yeast-based silage. Heliyon, 9(5).