Energy is the first-limiting nutrient for cows grazing pasture therefore, energy supplementation is necessary for high producing animals. In pasture-based systems, the concentrate is fed twice a day in the dairy parlour during the milking procedure. Consumption of large amounts of fermentable carbohydrates results in a drop in rumen pH and this may induce rumen acidosis. This may lead to reduced intake, lower fibre digestion and depressed milk yield. Supplemental yeast offer great possibilities in stabilising the rumen fermentation patterns and, therefore, improving dry matter intakes (DMI). This may increase milk production, milk composition parameters, rumen volatile fatty acid concentrations (VFA) which leads to higher profits. Investigating these responses, a trial was conducted, where live yeast (Levucell SC 10 ME-Titan) was supplemented to Jersey cows grazing ryegrass/kikuyu pastures, supplemented with 6 kg (as is) dairy concentrate per day split over two milking periods. Thirty multiparous high-producing Jersey cows between 30 and 120 days in milk (DIM) were selected, blocked and randomly allocated to control (no yeast) or live yeast treatment groups. Ten fistulated lactating cows were added in a cross-over design (two periods and two treatments) and all 40 cows strip grazed Italian ryegrass (Lollium multiflorum) and kikuyu pastures as one group. A new pasture strip was allocated after each milking and pasture was measured using a rising plate meter (RPM). The yeast product Levucell SC 10 ME – Titan containing Saccharomyces cerevisiae CNCM I-1077 was supplied by Lallemand S.A.S (19 rue des Briquetiers, 31702 Blagnac cedex, France). The Levucell SC 10 ME – Titan is a micro-encapsulated formulation for premix and pelleted feeds. The yeast treatment group had the yeast pelleted in with the dairy concentrate at a concentration of 167 g of yeast per ton of concentrate, to obtain the required intake of 1 g yeast per cow per day as specified by Lallemand. Milk yields were recorded daily and composite milk samples were taken every two weeks to determine, milk fat, protein, lactose, milk urea nitrogen (MUN) and somatic cell count (SCC) contents. The fistulated cows were adapted to their respective diets and treatments for 21 days after which the pH measurment, rumen fluid sampling, and In sacco study were conducted. Milk yield, 4% fat corrected milk (FCM) yield, milk protein and lactose percentages, SCC, body condition score (BCS), and live weight did not differ (P > 0.05) between treatments. The milk fat% however, was higher for the yeast supplemented cows at 4.24% compared to the control group of cows of 3.99% (P < 0.05). The mean acetic and total VFA concentration (mmol/L) for the control treatment was higher compared to the yeast treatment (P < 0.05). There was no difference in the fermentation patterns of VFA, the pH and NH3-N values measured between treatments (P > 0.05). The mean In sacco neutral detergent fibre (NDF), organic matter (OM) and DM disappearance was higher for the yeast treatment group of cows after a 12 and 24 hour incubation compared to the control group (P < 0.05). The mean ruminal NDF disappearance of ryegrass in cows supplemented with yeast increased by 11.9% and 6.3% compared to the control at the 12 and 24 hour incubation periods, respectively. With higher fibre digestibilities in the rumen and more acetate available at the mammary gland and subsequently higher milk fat percentages, the yeast effects on stimulating the cellulolytic bacteria in the rumen, may be a possible explanation for the results in the current study and it is well documented in previous studies. Live yeast supplementation resulted in higher milk fat percentages which improved milk price. / Dissertation (MSc(Agric))--University of Pretoria, 2011. / Animal and Wildlife Sciences / unrestricted

No description available.

No description available.

L'objectif de ce travail est de caractériser l'effet des levures vivantes Sc47 sur le métabolisme ruminal et l'utilisation digestive de la ration en lien avec le statut oxydo-réducteur du rumen chez des vaches laitières recevant des rations qui diffèrent dans leur composition. En effet, le milieu ruminal est très anaérobie et réducteur : les micro-organismes qui s'y développent sont à l'origine de ces conditions physico-chimiques particulières caractérisées par des valeurs de potentiel rédox (Eh) ou indice de Clark (rH) basses : respectivement dans cette étude entre –213 et –147 mV et entre 6.04 et 7.48 unités rH. L'impact de trois constituants du régime des vaches laitières d'une part sur le statut réducteur du milieu ruminal et d'autre part sur son métabolisme et/ou l'utilisation digestive de la ration a été testé en interaction avec l'addition de levures vivantes : un fourrage sec chez la vache tarie, deux concentrés azotés différant par le niveau de solubilité ruminal des protéines qu'il contient et enfin la nature de l'amidon, rapidement ou lentement dégradable dans le rumen chez la vache en lactation. Il apparaît nettement que le régime alimentaire ainsi que le niveau d'ingestion des animaux influencent directement le statut réducteur du rumen : un niveau réducteur bas étant favorable à l'activité d'une flore cellulolytique alors que des niveaux plus élevés s'avèrent être un indicateur de l'apparition de troubles métaboliques du rumen. En effet, le pouvoir réducteur ruminal est corrélé avec l'activité fermentaire qui s'y développe ainsi qu'à la structure des communautés bactériennes en présence. D'après nos résultats, l'effet de la levure vivante sur les conditions réductrices du rumen semble fortement conditionné par le niveau du statut réducteur induit par le régime alimentaire : les conditions réductrices ruminales peuvent être renforcées dans la mesure où le Eh initial se trouve, dans notre étude, entre –174 et –152 mV. Ce renforcement serait favorable à l'activité de la flore fibrolytique si celle-ci n'est pas dominante, ce groupe fonctionnel participant alors également au maintien des conditons réductrices. En outre, la levure vivante aurait un impact direct sur les bactéries protéolytiques favorisant la quantité de protéines "by pass" si bien que la valeur azotée de la ration peut être améliorée en particulier en termes de PDIA. / The objective of this work is to characterize the effect of live yeast Sc47 on ruminal metabolism and ration digestibility in relation to ruminal redox status of dairy cows fed diets that differed in their composition. Indeed, the rumen environment is very anaerobic and very reducing : the inhabiting micro-organisms are the main sources of particular physic-chemical conditions characterized by low values of redox potential (Eh) or Clark’s exponent (rH): in this study, values were between –213 and –147 mV and between 6.04 and 7.48 units for Eh and rH, respectively. The impact of three constituting ingredients of the diet of dairy cows was investigated. On the one hand, the reducing status of rumen was observed and on the other hand, the metabolism and/or digestibility of the diet with or without addition of live yeast was explored. The tested constituents were: hay for dry dairy cows, two concentrates differing in nitrogen levels of ruminal solubility, and two energetic concentrates differing in rate of ruminal degradation of starch – quickly or slowly degradable in the rumen of lactating dairy cows. It clearly appeared that the diet and the level of dry matter intakes of animals directly influenced the reducing ruminal status: low levels being favorable to the activity of cellulolytic microflora whereas higher levels appeared to be indicators of metabolic disorders occuring in the rumen. Indeed, the reducing power was correlated to rumen fermentative activity and the structure of bacterial communities involved. According to our results, the effect of live yeast on rumen reducing conditions appeared strongly influenced by the level of the intrinsic reducing status induced by diet: reducing conditions in the rumen could be strengthened to the extent that the original values ranged between –174 and –152 mV. This reinforced ruminal conditions would uphold the activity of fibrolytic microflora if it is not dominant, this functional group then participating to the maintenance of reducing conditions. In addition, live yeast has a direct impact on proteolytic bacteria promoting by-pass proteins so that the protein value of the ration may be improved especially in terms of PDIA.

No description available.

No description available.

The effect of increased neutral detergent fibre digestibility (NDFD) of sugarcane silage on intake, rumen kinetics and metabolism, microbial population, performance, and body fatness of beef cattle was evaluated through two trials. In the metabolism trial, eight ruminal-cannulated Nellore steers were used in a replicated 4×4 Latin square design. In the performance trial, forty-eight Nellore young bulls were used in a complete randomized block design with a 2×2 factorial arrangement of treatments. Two sugarcane genotypes with high or low NDFD harvested for silage in two maturity stages were used (2 genotypes and 2 maturity stages). Diets were formulated with 40% of sugarcane on dry matter (DM) basis. Intake of DM was likely limited by metabolic feedback. The DM intake (DMI) of cannulated steers was reduced when late-maturity sugarcane was fed, but only with low-NDFD genotype. Turnover and passage rate of NDF was accelerated when high-NDFD genotype was fed. Rumen DM, NDF and iNDF pools were greater when diets with the low-NDFD genotype were fed. There was a tendency for greater relative populations of F. succinogenes and R. albus when animals were fed with diets containing low-NDFD genotype. Performance and carcass characteristics were not affected by treatments. Excess of NFC and fermentation end products of sugarcane silage can limit intake by metabolic pathway. High-NDFD genotype can accelerated NDF turnover and passage rate in the rumen. Late-maturity ensiled sugarcane can reduce DMI of beef steers fed with low-NDFD genotype. The effect of live yeast (LY - Saccharomyces cerevisiae CNCM I-1077) on in situ fiber digestibility, rumen fermentation, and rumen cellulolytic bacteria population of grazing Nellore cattle was evaluated throughout the year. Eight rumen cannulated steers were used in a 2x4 factorial arrangement of treatments: with or without LY, and the four seasons of the year. Yeast was given daily to provide 8x109 CFU per animal. Animals were kept on a rotational grazing system with mineral supplementation. Every 45 d, in situ rumen NDF degradability of 5 reference forages was determined after 24 and 48h incubation. Rumen fluid was collected to measure yeast count and fermentation parameters, and rumen contents collected for quantitative PCR quantification of cellulolytic bacteria. Although pasture composition varied greatly throughout the year, there was no LY*season interaction. Yeast supplementation increased NDF degradability in all seasons. Among the four rumen bacteria evaluated, R. flavefaciens was the most prevalent and LY increased R. flavefaciens population in the summer and spring. Supplementing LY can benefit fibre-degrading bacteria and increase fibre degradability of grazing animals, independently of the season. / O efeito do aumento da digestibilidade da fibra detergente neutro (DFDN) da silagem de cana-de-açúcar sobre consumo, cinética e metabolismo ruminal, população microbiana, desempenho e características de carcaça de bovinos de corte foram avaliados através de dois experimentos. No experimento de metabolismo, oito novilhos Nelore canulados no rúmen foram utilizados em delineamento experimental com dois quadrados latinos 4×4 contemporâneos. No experimento de desempenho, quarenta e oito novilhos nelore foram usados em delineamento em blocos inteiramente casualizados com arranjo de tratamento em fatorial 2×2. Dois genótipos de cana-de-açúcar com alta e baixa-DFDN colhidos para ensilagem em dois estágios de maturidade (2 genótipos e 2 estágios de maturidade). As dietas foram formuladas contendo 40% de silagem de cana-de-açúcar na matéria seca. O consumo de matéria seca (CMS) foi limitado pela via metabólica. O CMS dos novilhos canulados no rúmen foi reduzido quando foram alimentados com a cana-de-açúcar colhida na maturidade tardia, mas somente para o genótipo de baixa-DFDN. A taxa de passagem e o turnover de FDN foram acelerados quando o genótipo de alta-DFDN foi fornecido. O pool ruminal de MS, FDN e FDNi foram maiores para as dietas contendo o genótipo de baixa-DFDN. Houve tendência para maior população relativa de F. succinogenes e R. albus quando os animais foram alimentado com dietas contendo o genótipo de baixa-DFDN. O desempenho e as características de carcaça não foram afetados pelos tratamentos. O excesso de carboidratos não fibrosos (CNF) e os produtos de fermentação das silagens podem limitar o consumo pela via metabólica. O genótipo de alta-DFDN pode acelerar a taxa de passagem e o turnover de FDN no rúmen. O CMS pode ser reduzido quando o genótipo de baixa-DFDN é colhido para ensilagem com maturidade tardia. O feito da suplementação com levedura viva (LV - Saccharomyces cerevisiae CNCM I-1077) sobre a digestibilidade in situ, fermentação ruminal e população de bactérias celulolíticas no rúmen de bovinos Nelore em pastejo foi avaliado ao longo de um ano. Oito novilhos canulados no rúmen foram usados em arranjo fatorial 2×4: com ou sem LV e quantro estações do ano. O tratamento com LV foi realizado diariamente para promover uma suplementação de 8x109 UFC por animal. Os animais foram mantidos em sistema de pastejo rotativo com suplementação mineral. A cada 45 dias, foi realizada a degradação de FDN n situ de 5 forragens referencia, determinada após 24 e 48h de incubação ruminal. O fluido ruminal foi coletado para avaliar a contagem de leveduras e os parâmetros de fermentação, e ainda para a quantificação de bactérias celulolíticas por PCR. Mesmo com grande variação da qualidade do pasto ao longo do ano, não foi observado interação entre LV*estação do ano. A suplementação com LV aumentou a degradabilidade da FDN em todas as estações do ano. Entre as quatro bactérias ruminais avaliadas, a R. flavefaciens foi a mais prevalente e o tratamento com LV aumentou sua população relativa no verão e na primavera. A suplementação com LV pode beneficiar bactérias degradadoras de FDN e aumentar a digestibilidade ruminal de fibra em animais em pastejo, independentemente da estação do ano.

Orientador: Ricardo Andrade Reis / Banca: Telma Teresinha Berchielli / Banca: Ana Claudia Ruggieri / Banca: Flávio Augusto Portela Santos / Banca: Valdo Rodrigues Herling / Resumo: O objetivo deste estudo foi avaliar os efeitos da suplementação protéica e do uso de monensina e/ou Saccharomyces cerevisiae, nos parâmetros da fermentação ruminal (pH, NH3 e ácidos acético, propiônico e butírico), no consumo de forragem e desempenho de novilhas de corte recriadas em pastagem de capim-Marandú, em duas épocas do ano (transição águas/secas e secas). Os tratamentos avaliados foram: sal mineral (SM); suplemento protéico (SP); suplemento protéico com monensina (SPM); suplemento protéico com levedura (SPL); e suplemento protéico com monensina e levedura (SPML). De acordo com a fermentação ruminal, observou-se alterações no teor do ácido propiônico e razão C2:C3, em resposta ao tratamento SPM. Nas águas, observou-se a influência do pasto no padrão de fermentação ruminal, pois a concentração total de AGCC (133,1mM), ácido acético (101, 4 mM), ácido propiônico (21,1 mM) e ácido butírico (10,7 mM) foram superiores aos demais tratamentos às 6 h. Nas secas, a suplementação mineral protéica melhorou os atributos de fermentação ruminal, porém não houve diferenças estatísticas entre os tratamentos e, a inclusão de levedura à dieta (SPL) aumentou as concentrações de AGCCtotal (109,2mM), acético (80,7mM), propiônico (19,1mm) e butírico (9,4 mM), em relação à inclusão de monensina (67,0, 50,4, 11,8 e 4,8 mM, respectivamente). Quanto ao teor de NH3, na transição águas/secas e secas, respectivamente, às 3h após a refeição foi de 6,7 e 4,8 mg/dL nos animais que consumiam...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: To evaluate the protein supplementation associated with monensin and/or Saccharomyces cerevisiae effects on the ruminal parameters (pH, NH3, acetic, propionic and butiric acids), dry matter intake, and heifers performance grazing Marandu grass pasture in different times (the end of rainy and dry season) this trial was conducted. The evaluated treatments were: mineral salt (MS), protein supplement (PS), PS plus monensin (PSM), PS plus S. cerevisiae (PSL), PS plus monensin and S. cerevisiae (PSML). The PSM changed the ruminal propionic acid values and the C2:C3 ratio. In the end of rainy season, the forage characteristics affected the ruminal parameters. Total fatty acid (133.1 mM), acetic (101.4 mM), propionic (21.1 mM), and butiric acid (10.7 mM) values were greatest on the PSM animals evaluated at six hours after the supplementation. In the dry season, the protein supplementation in general changed the ruminal parameters. In the end of the rainy season and dry season, the MS animals presented NH3 level, respectively of the 6.7 and 4.8 mg/dL, three hours after supplementation. However, the supplemented animals, in average showed 22.3, and 27.6 mg/dL of the ruminal NH3. Low herbage mass was observed on August (2.8 t/ha), and September (1.9 t/ha). The weights gains were 0.4, and 0.2 kg/d on the SP, and 0.2, and -0.06 kg/d on the SM animals, on August and September, respectively. On the end of the rainy season the PSM animal showed 9.8 kg more gain than the PSML. During the end of rainy season the SM heifers presented highest forage intake (2.16% BW), and monensin addition reduced forage intake in 18%. In the dry season the MS heifers presented 2.08% BW of forage, compared to the supplemented animals (1.55% BW)...(Complete abstract click electronic access below) / Doutor

The effect of increased neutral detergent fibre digestibility (NDFD) of sugarcane silage on intake, rumen kinetics and metabolism, microbial population, performance, and body fatness of beef cattle was evaluated through two trials. In the metabolism trial, eight ruminal-cannulated Nellore steers were used in a replicated 4×4 Latin square design. In the performance trial, forty-eight Nellore young bulls were used in a complete randomized block design with a 2×2 factorial arrangement of treatments. Two sugarcane genotypes with high or low NDFD harvested for silage in two maturity stages were used (2 genotypes and 2 maturity stages). Diets were formulated with 40% of sugarcane on dry matter (DM) basis. Intake of DM was likely limited by metabolic feedback. The DM intake (DMI) of cannulated steers was reduced when late-maturity sugarcane was fed, but only with low-NDFD genotype. Turnover and passage rate of NDF was accelerated when high-NDFD genotype was fed. Rumen DM, NDF and iNDF pools were greater when diets with the low-NDFD genotype were fed. There was a tendency for greater relative populations of F. succinogenes and R. albus when animals were fed with diets containing low-NDFD genotype. Performance and carcass characteristics were not affected by treatments. Excess of NFC and fermentation end products of sugarcane silage can limit intake by metabolic pathway. High-NDFD genotype can accelerated NDF turnover and passage rate in the rumen. Late-maturity ensiled sugarcane can reduce DMI of beef steers fed with low-NDFD genotype. The effect of live yeast (LY - Saccharomyces cerevisiae CNCM I-1077) on in situ fiber digestibility, rumen fermentation, and rumen cellulolytic bacteria population of grazing Nellore cattle was evaluated throughout the year. Eight rumen cannulated steers were used in a 2x4 factorial arrangement of treatments: with or without LY, and the four seasons of the year. Yeast was given daily to provide 8x109 CFU per animal. Animals were kept on a rotational grazing system with mineral supplementation. Every 45 d, in situ rumen NDF degradability of 5 reference forages was determined after 24 and 48h incubation. Rumen fluid was collected to measure yeast count and fermentation parameters, and rumen contents collected for quantitative PCR quantification of cellulolytic bacteria. Although pasture composition varied greatly throughout the year, there was no LY*season interaction. Yeast supplementation increased NDF degradability in all seasons. Among the four rumen bacteria evaluated, R. flavefaciens was the most prevalent and LY increased R. flavefaciens population in the summer and spring. Supplementing LY can benefit fibre-degrading bacteria and increase fibre degradability of grazing animals, independently of the season. / O efeito do aumento da digestibilidade da fibra detergente neutro (DFDN) da silagem de cana-de-açúcar sobre consumo, cinética e metabolismo ruminal, população microbiana, desempenho e características de carcaça de bovinos de corte foram avaliados através de dois experimentos. No experimento de metabolismo, oito novilhos Nelore canulados no rúmen foram utilizados em delineamento experimental com dois quadrados latinos 4×4 contemporâneos. No experimento de desempenho, quarenta e oito novilhos nelore foram usados em delineamento em blocos inteiramente casualizados com arranjo de tratamento em fatorial 2×2. Dois genótipos de cana-de-açúcar com alta e baixa-DFDN colhidos para ensilagem em dois estágios de maturidade (2 genótipos e 2 estágios de maturidade). As dietas foram formuladas contendo 40% de silagem de cana-de-açúcar na matéria seca. O consumo de matéria seca (CMS) foi limitado pela via metabólica. O CMS dos novilhos canulados no rúmen foi reduzido quando foram alimentados com a cana-de-açúcar colhida na maturidade tardia, mas somente para o genótipo de baixa-DFDN. A taxa de passagem e o turnover de FDN foram acelerados quando o genótipo de alta-DFDN foi fornecido. O pool ruminal de MS, FDN e FDNi foram maiores para as dietas contendo o genótipo de baixa-DFDN. Houve tendência para maior população relativa de F. succinogenes e R. albus quando os animais foram alimentado com dietas contendo o genótipo de baixa-DFDN. O desempenho e as características de carcaça não foram afetados pelos tratamentos. O excesso de carboidratos não fibrosos (CNF) e os produtos de fermentação das silagens podem limitar o consumo pela via metabólica. O genótipo de alta-DFDN pode acelerar a taxa de passagem e o turnover de FDN no rúmen. O CMS pode ser reduzido quando o genótipo de baixa-DFDN é colhido para ensilagem com maturidade tardia. O feito da suplementação com levedura viva (LV - Saccharomyces cerevisiae CNCM I-1077) sobre a digestibilidade in situ, fermentação ruminal e população de bactérias celulolíticas no rúmen de bovinos Nelore em pastejo foi avaliado ao longo de um ano. Oito novilhos canulados no rúmen foram usados em arranjo fatorial 2×4: com ou sem LV e quantro estações do ano. O tratamento com LV foi realizado diariamente para promover uma suplementação de 8x109 UFC por animal. Os animais foram mantidos em sistema de pastejo rotativo com suplementação mineral. A cada 45 dias, foi realizada a degradação de FDN n situ de 5 forragens referencia, determinada após 24 e 48h de incubação ruminal. O fluido ruminal foi coletado para avaliar a contagem de leveduras e os parâmetros de fermentação, e ainda para a quantificação de bactérias celulolíticas por PCR. Mesmo com grande variação da qualidade do pasto ao longo do ano, não foi observado interação entre LV*estação do ano. A suplementação com LV aumentou a degradabilidade da FDN em todas as estações do ano. Entre as quatro bactérias ruminais avaliadas, a R. flavefaciens foi a mais prevalente e o tratamento com LV aumentou sua população relativa no verão e na primavera. A suplementação com LV pode beneficiar bactérias degradadoras de FDN e aumentar a digestibilidade ruminal de fibra em animais em pastejo, independentemente da estação do ano.

Made available in DSpace on 2014-06-11T19:33:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-12Bitstream added on 2014-06-13T20:25:12Z : No. of bitstreams: 1 bertipaglia_lma_dr_jabo.pdf: 804905 bytes, checksum: 0d0438eeb116ed2ed0780bcd278b3b2c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Bellman Nutricao Animal Ltda / Brascan - Fazenda Bartira / Saf do Brasil - DiviSão Agropecuaria / O objetivo deste estudo foi avaliar os efeitos da suplementação protéica e do uso de monensina e/ou Saccharomyces cerevisiae, nos parâmetros da fermentação ruminal (pH, NH3 e ácidos acético, propiônico e butírico), no consumo de forragem e desempenho de novilhas de corte recriadas em pastagem de capim-Marandú, em duas épocas do ano (transição águas/secas e secas). Os tratamentos avaliados foram: sal mineral (SM); suplemento protéico (SP); suplemento protéico com monensina (SPM); suplemento protéico com levedura (SPL); e suplemento protéico com monensina e levedura (SPML). De acordo com a fermentação ruminal, observou-se alterações no teor do ácido propiônico e razão C2:C3, em resposta ao tratamento SPM. Nas águas, observou-se a influência do pasto no padrão de fermentação ruminal, pois a concentração total de AGCC (133,1mM), ácido acético (101, 4 mM), ácido propiônico (21,1 mM) e ácido butírico (10,7 mM) foram superiores aos demais tratamentos às 6 h. Nas secas, a suplementação mineral protéica melhorou os atributos de fermentação ruminal, porém não houve diferenças estatísticas entre os tratamentos e, a inclusão de levedura à dieta (SPL) aumentou as concentrações de AGCCtotal (109,2mM), acético (80,7mM), propiônico (19,1mm) e butírico (9,4 mM), em relação à inclusão de monensina (67,0, 50,4, 11,8 e 4,8 mM, respectivamente). Quanto ao teor de NH3, na transição águas/secas e secas, respectivamente, às 3h após a refeição foi de 6,7 e 4,8 mg/dL nos animais que consumiam... / To evaluate the protein supplementation associated with monensin and/or Saccharomyces cerevisiae effects on the ruminal parameters (pH, NH3, acetic, propionic and butiric acids), dry matter intake, and heifers performance grazing Marandu grass pasture in different times (the end of rainy and dry season) this trial was conducted. The evaluated treatments were: mineral salt (MS), protein supplement (PS), PS plus monensin (PSM), PS plus S. cerevisiae (PSL), PS plus monensin and S. cerevisiae (PSML). The PSM changed the ruminal propionic acid values and the C2:C3 ratio. In the end of rainy season, the forage characteristics affected the ruminal parameters. Total fatty acid (133.1 mM), acetic (101.4 mM), propionic (21.1 mM), and butiric acid (10.7 mM) values were greatest on the PSM animals evaluated at six hours after the supplementation. In the dry season, the protein supplementation in general changed the ruminal parameters. In the end of the rainy season and dry season, the MS animals presented NH3 level, respectively of the 6.7 and 4.8 mg/dL, three hours after supplementation. However, the supplemented animals, in average showed 22.3, and 27.6 mg/dL of the ruminal NH3. Low herbage mass was observed on August (2.8 t/ha), and September (1.9 t/ha). The weights gains were 0.4, and 0.2 kg/d on the SP, and 0.2, and -0.06 kg/d on the SM animals, on August and September, respectively. On the end of the rainy season the PSM animal showed 9.8 kg more gain than the PSML. During the end of rainy season the SM heifers presented highest forage intake (2.16% BW), and monensin addition reduced forage intake in 18%. In the dry season the MS heifers presented 2.08% BW of forage, compared to the supplemented animals (1.55% BW)...(Complete abstract click electronic access below)