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The effect of Saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs
Thesis (MScAgric)--Stellenbosch University, 2025.
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| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613737506045952 |
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| access_status_str | Open Access |
| author | De la Harpe, Jean Etienne |
| author2 | Van Zyl, Johan Hendrik Combrink
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| author_browse | De la Harpe, Jean Etienne Van Zyl, Johan Hendrik Combrink |
| author_facet | Van Zyl, Johan Hendrik Combrink
De la Harpe, Jean Etienne |
| author_sort | De la Harpe, Jean Etienne |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132160 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:54.381Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132160 The effect of Saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs De la Harpe, Jean Etienne Van Zyl, Johan Hendrik Combrink Lambrechts, Helet Cruywagen, C. W. Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science. Lambs Lambs -- Feeding and feeds Feedlots -- Economic aspects Saccharomyces cerevisiae Calcareous marine algae Proteins in animal nutrition Amino acids in animal nutrition Feed additives -- Evaluation Feed utilization efficiency UCTD Thesis (MScAgric)--Stellenbosch University, 2025. de la Harpe, J. E. 2025. The effect of Saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/04b167cf-721f-4526-83a1-cf9633edf151 ENGLISH ABSTRACT: To meet global food demands, food production must nearly double by 2050, driving farmers toward intensive practices such as lamb feedlotting. This method, increasingly popular due to increasing lamb meat prices and frequent droughts in Southern Africa, involves purchasing young lambs, feeding them high-concentrate diets, and managing them intensively to maximise growth before puberty. Feedlot profitability hinges on factors like lamb purchase price, meat price post-slaughter, carcass classification, feed costs, and feed conversion ratio (FCR), which measures feed efficiency. Feed costs account for about 70% of total expenses, making FCR critical to profitability. Feedlot diets often contain high starch and low fibre levels, essential for rapid growth but potentially harmful to rumen health. High-starch feedlot diets can lead to subacute ruminal acidosis (SARA), a common metabolic disorder in intensive feeding systems caused by excessive acid build-up in the rumen, resulting when the rumen's buffering capacity is overwhelmed. This results in reduced microbial activity, impaired digestion, and diminished production performance. Managing SARA is critical, as it can significantly impact animal health and wellbeing, and overall productivity and profitability. Feed additives like live yeasts such as Saccharomyces cerevisiae (SC); and calcareous marine algae, a seaweed-derived buffer, are increasingly used to mitigate the risks of SARA. Live yeasts enhance rumen stability by scavenging oxygen, promoting beneficial microbes, and maintaining optimal rumen pH. Similarly, calcareous marine algae, rich in calcium and magnesium carbonate, regulates rumen acidity and supports microbial activity. Both additives have shown promise in improving rumen function and overall productivity, with SC reducing the incidence of SARA. While the inclusion of calcareous marine algae is well-established in dairy cow diets, its broader impacts on ruminant production performance warrants investigation. The results of this study highlight significant variability in the outcomes of feeding lamb diets with differing dietary energy levels and the inclusion of Saccharomyces cerevisiae (SC) and calcareous marine algae (CMA). While low-energy (LE) diets with 10.08 MJ/kg supported higher average daily gain (ADG) of 0.40 kg ± 0.06 and total dry matter intake (DMI) (44.56 kg ± 3.49), high-energy (HE) diets with 10.53 MJ/kg led to greater dressing percentage (DP) (45.09% ± 1.64) and lower feed costs (R173.40 ± 3.22). However, dietary energy levels did not affect feed conversion ratio (FCR), carcass weight, or gross profit. When considering the inclusion of SC and CMA, it resulted in inconsistent effects, with the control group showing the highest DP (45.00 % ± 1.39), carcass weight (19.54 kg ± 1.18), and profit margins (R101.67 ± 12.65). Saccharomyces cerevisiae inclusion increased acetate concentrations, while the combined buffer (CB) group elevated iso-butyrate concentrations, but neither buffer influenced ruminal pH, volatile fatty acid (VFA) concentrations, or rumen ammonia nitrogen (RAN) levels significantly. Nutrient digestibility results were mixed; LE diets improved crude protein (CP) digestibility, but the inclusion of CMA negatively impacted CP and neutral detergent fibre (NDF) digestibility. Saccharomyces cerevisiae had no effect on CP digestibility, while the control group exhibited the highest digestibility coefficients for organic matter (OM) (0.79 ± 0.02), CP (0.76 ± 0.02), and NDF (0.61 ± 0.03). These findings underscore the need for further research to optimize SC and CMA inclusion levels, particularly in higher-energy diets, to ensure consistent and favourable outcomes. AFRIKAANSE OPSOMMING: Om aan die wêreldwye aanvraag aan voedsel te voldoen, moet voedselproduksie teen 2050 byna verdubbel, wat boere dryf na intensiewe praktyke soos lam voerkrale. Hierdie metode, wat toenemend gewild raak as gevolg van stygende vleispryse en gereelde droogtes in Suid-Afrika, behels die aankoop van jong lammers, die voer van hoë-konsentraat diëte en intensiewe bestuur om groei voor puberteit te benut. Die winsgewendheid van voerkrale hang af van faktore soos die aankoopprys van lammers, vleisprys ná slag, karkasklassifikasie, voerpryse en voeromsetverhouding (FCR), wat voereffektiwiteit meet. Voerkoste beloop ongeveer 70% van die totale uitgawes, wat FCR krities vir winsgewendheid maak. Voerkraaldiëte bevat dikwels hoë stysel- en lae veselvlakke, wat noodsaaklik is vir vinnige groei, maar potensieel nadelig vir rumengesondheid. Hoë-stysel voerkraaldiëte kan lei tot subakute ruminale asidose (SARA), ’n algemene metaboliese versteuring in intensiewe voedingsisteme wat veroorsaak word deur oormatige suur produksie in die rumen wanneer die rumen se bufferkapasiteit oorweldig word. Dit lei tot verminderde mikrobiese aktiwiteit, verswakte vertering en laer produksieprestasie. Die bestuur van SARA is noodsaaklik, aangesien dit ’n beduidende impak op diergesondheid, welsyn, en algehele produktiwiteit en winsgewendheid kan hê. Voer bymiddels soos lewendige gis, spesifiek Saccharomyces cerevisiae (SC), en kalkhoudende mariene alge (CMA), ’n seewier-afgeleide buffer, word toenemend gebruik om die risiko’s van SARA te verminder. Lewende gis bevorder rumenstabiliteit deur suurstof te verwyder, voordelige mikrobes te ondersteun en optimale rumen-pH te handhaaf. Net so help kalkhoudende mariene alge, ryk aan kalsium- en magnesiumkarbonaat, om rumensuurheid te reguleer en mikrobiese aktiwiteit te ondersteun. Beide bymiddels het belowende resultate getoon in die verbetering van rumenfunksie en algehele produktiwiteit, met SC wat die voorkoms van SARA verminder. Terwyl die insluiting van kalkhoudende mariene alge goed gevestig is in melkkoeidiëte, regverdig die breër impak daarvan op herkouerproduksieprestasie ondersoek. Die resultate van hierdie studie beklemtoon beduidende variasie in die uitkomste van voeding van lamsdiëte met verskillende dieetenergievlakke en die insluiting van Saccharomyces cerevisiae (SC) en kalkhoudende mariene alge (CMA). Terwyl lae-energie (LE) diëte met 10,08 MJ/kg hoër gemiddelde daaglikse toename (GDT) van 0,40 kg ± 0,06 en totale droëmateriaal-inname (DMI) (44,56 kg ± 3,49) ondersteun het, het hoë- energie (HE) diëte met 10,53 MJ/kg gelei tot 'n beter uitslag persentasie (DP) (45.09% ± 1.64) en laer voerkoste (R173,40 ± 3,22). Dieetenergievlakke het egter nie voeromsettingsverhouding (VOV), karkasgewig of bruto wins beïnvloed nie. Met betrekking tot die insluiting van SC en CMA het dit inkonsekwente effekte getoon, met die kontrolegroep wat die hoogste DP (45.00% ± 1.39), karkasgewig (19.54 kg ± 1.18) en winsmarges (R101.67 ± 12.65) gehad het. Die insluiting van Saccharomyces cerevisiae het asetaatkonsentrasies verhoog, terwyl die gekombineerde buffer groep (CB) iso-butiraat konsentrasies verhoog het, maar geen buffer het rumen-pH, vlugtige vetsuur (VFA) konsentrasies of rumen- ammoniakstikstof vlakke (RAN) beduidend beïnvloed nie. Nutriëntverteerbaarheid het gemengde resultate getoon; LE-diëte het ru-proteïen (CP) verteerbaarheid verbeter, maar die insluiting van CMA het CP- en NDF verteerbaarheid negatief beïnvloed. Saccharomyces cerevisiae het geen effek op CP-verteerbaarheid gehad nie, terwyl die kontrolegroep (C) die hoogste verteerbaarheidskoëffisiënte vir organiese materiaal (OM) (0.79 ± 0.02), CP (0.76 ± 0.02), en NDF (0.61 ± 0.03) getoon het. Hierdie bevindings beklemtoon die behoefte aan verdere navorsing om SC- en CMA-insluitingsvlakke te optimaliseer, veral in hoër-energie diëte, om konsekwente en gunstige uitkomste te verseker. Masters 2025-05-28T09:07:16Z 2025-05-28T09:07:16Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132160 en Stellenbosch University 74 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Lambs Lambs -- Feeding and feeds Feedlots -- Economic aspects Saccharomyces cerevisiae Calcareous marine algae Proteins in animal nutrition Amino acids in animal nutrition Feed additives -- Evaluation Feed utilization efficiency UCTD De la Harpe, Jean Etienne The effect of Saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs |
| title | The effect of Saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs |
| title_full | The effect of Saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs |
| title_fullStr | The effect of Saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs |
| title_full_unstemmed | The effect of Saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs |
| title_short | The effect of Saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs |
| title_sort | effect of saccharomyces cerevisiae and calcareous marine algae supplementation on the performance of feedlot lambs |
| topic | Lambs Lambs -- Feeding and feeds Feedlots -- Economic aspects Saccharomyces cerevisiae Calcareous marine algae Proteins in animal nutrition Amino acids in animal nutrition Feed additives -- Evaluation Feed utilization efficiency UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132160 |
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