Methane is a potent greenhouse gas with a global warming potential 21 times that of carbon dioxide. Globally, ruminants are the main anthropogenic contributors to methane release to the atmosphere. Methane is produced in the gastrointestinal tract of ruminants, mostly within the rumen by methanogenic archaea. However, methane production represents a loss of 2 to 12% of dietary gross energy for the animal, which could otherwise be available for growth or milk production. Therefore, mitigation of methane production by ruminants could produce both economic and environmental benefits, with more sustainable and energy efficient livestock, and offering a promising way of slowing global warming. Despite extensive research undertaken to find ways of reducing methane emissions from ruminants, progress has been relatively limited. Furthermore, there is still a lack of studies linking rumen microbiology and ruminant nutrition and production. The central purpose of this research was to investigate feed additives to reduce methane emissions and to understand associated changes that occur in the rumen microbiota. For the first experiment (Chapter 2), biochar was evaluated as an antimethanogenic compound for beef cattle. The in vitro gas production technique was used to study the effects of biochar on rumen fermentation and methane production. Overall, methane production was reduced by 5% by the addition of biochar compounds (10 g/kg of substrate). The observed reduction in methane produced was not associated with a change in volatile fatty acid profile suggesting biochar primarily inhibited fermentation. Ammonia concentration was significantly reduced with biochar inclusion. Because different biochars had different effects on methane production, further investigation of relationships between the physicochemical properties of biochars and antimethanogenic effects are necessary. However, due to the small reduction in methane production recorded, research with biochar was discontinued. Encapsulated nitrate was then explored as an antimethanogenic additive and as an alternative non-protein nitrogen source to urea (Chapter 3). The effect of using encapsulated nitrate as a replacement for urea or dietary protein, plus the addition of inorganic sulphur, on enteric methane emissions, nutrient digestibility, nitrogen utilization and microbial protein synthesis from crossbred beef steers were studied. In addition, nitrate toxicity and eating behaviour were investigated. The inclusion of encapsulated nitrate reduced methane production compared to urea and a true protein source, with no adverse effects on rumen fermentation or nitrogen metabolism and no effects with the inclusion of elemental sulphur. The level of addition of encapsulated nitrate (14.3 g nitrate /kg DM) and the time of adaptation chosen for this study (14 days) were adequate to avoid nitrate toxicity. Finally, the effects of adding nitrate inclusion to different basal diets on rumen microbial populations and relationships of these populations with methane production were investigated (Chapter 4). The V4 hypervariable regions of the bacterial and archaea 16S rRNA genes were amplified and sequenced. Effects on microbial population induced by nitrate were dependant on the basal diet but nitrate altered specific archaeal and bacterial OTUs consistently between studies. A direct and strong correlation between some archaea taxonomic groups and OTUs with methane production was observed.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-13T17:57:06Z No. of bitstreams: 1 thaisbarrosrispoli.pdf: 1300847 bytes, checksum: 5286992b6dd88da252179302aabe7aff (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-07-14T10:35:05Z (GMT) No. of bitstreams: 1 thaisbarrosrispoli.pdf: 1300847 bytes, checksum: 5286992b6dd88da252179302aabe7aff (MD5) / Made available in DSpace on 2016-07-14T10:35:05Z (GMT). No. of bitstreams: 1 thaisbarrosrispoli.pdf: 1300847 bytes, checksum: 5286992b6dd88da252179302aabe7aff (MD5) Previous issue date: 2011-02-18 / Os protozoários ciliados fazem parte da microbiota ruminal e juntamente com as bactérias fungos e protozoários flagelados desempenham funções bioquímicas e fisiológicas importantes para os ruminantes, principalmente no metabolismo dos nutrientes. Entretanto, seu papel no rúmen, ainda não é totalmente claro, podendo trazer tanto efeitos benéficos como prejudiciais para a produção animal. O presente estudo objetivou caracterizar as populações de protozoários ciliados no rúmen de novilhos alimentados com dietas adicionadas de monensina ou produtos à base de própolis LLOS, avaliando o impacto da suplementação desses aditivos em curto prazo de tempo sobre as populações de ciliados. Cinco novilhos, fistulados no rúmen e distribuídos no delineamento quadrado latino (5X5) receberam dieta constituída por 47% de silagem de milho e 53% de concentrado à base de milho moído e farelo de soja. Foram testadas dietas sem aditivos (controle), com adição de monensina ou produtos à base de própolis LLOSB1+, LLOSC1+ ou LLOSC1++. As amostras do conteúdo ruminal foram coletadas antes do inicio de cada período amostral (dia 0) e 8, 15 e 21 dias após o início de cada período amostral, sendo que, no dia de cada coleta foram retiradas amostras antes do fornecimento da dieta experimental (0h) e 3 e 6 horas depois da suplementação. O gênero predominante nas dietas foi o Entodinium, representando valor acima de 97% da densidade total de ciliados. As populações de ciliados no rúmen dos novilhos não foram alteradas pela suplementação com o aditivo monensina ou produtos à base de própolis LLOS. O pH ruminal alterou-se apenas entre os tempos de amostragem. As populações de Entodinium aumentaram após 15 dias da adição do produto à base de propolis LLOSB1+ e após 21 dias foi verificado um efeito negativo desse aditivo sobre os ciliados, que aumentaram, retornando aos níveis iniciais. Os ciliados diminuíram após 8 dias de adição de monensina na dieta, restabelecendo-se apos 15 da suplementação e tornando a diminuir no final do experimento. As populações do gênero Entodinium ao longo do experimento foram alteradas durante os períodos experimentais, especialmente com a suplementação dos produtos à base de própolis LLOS o que pode ter influenciado os resultados encontrados. Sugere-se assim, o aumento do período experimental e substituição do delineamento quadrado latino em trabalhos futuros. / The ciliated protozoa are part of the rumen microbial and together with bacteria, fungi and flagellate protozoa play important biochemical and physiological functions for ruminants, especially in the metabolism of nutrients. However, its role in the rumen yet is not entirely clear, and it may bring both beneficial and harmful effects to animal production. This study aimed to characterize the ciliated protozoa population in the rumen of steers fed with diets containing monensin or products based on propolis LLOS, evaluating the impact of supplementation of these additives in a short period of time on the abundance of ciliates. Five steers, fistulated in the rumen and distributed in Latin square design (5X5) were fed with a diet consisting of 47% corn silage and 53% concentrate based on grinded corn and bran soybean. Diets were tested without additives (control), with the addition of monensin or products based on propolis LLOSB1+, LLOSC1+ and LLOSC1++. The samples of rumen contents were collected before the start of each sampling period (day 0) and 8, 15 and 21 days after the start of each sampling period, whereas, on each collect day were collected samples before the supply of experimental diet (0 h) and 3 and 6 hours later supplementation. The predominant genus in the diets was the Entodinium, representing a value above 97% of the total density of ciliates. The ciliate population in the rumen of steers were not altered by supplementation with the additive monensin or products based on propolis LLOS. Rumen pH changed only between times of sampling. The Entodinium population increased after 15 days of the products addition based on propolis LLOSB1+ and after 21 days it was observed a negative effect of this additive on the ciliates. They increased, returning to their initial levels. The ciliates got shorter after 8 days of monensina addition in the diet, reestablishing after 15 days of supplementation and getting shorter again at the end of the experiment. The genus Entodinium population throughout the experiment were altered during the experimental periods, especially with the addition of the products based on propolis LLOS which may have affected the results. It is therefore suggested, an increase of the experimental period and the replacement of the Latin square design in future works.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This study was carried out to evaluate methods in ruminant nutrition: use of fecal index to estimate intake and use of purine or purine derivatives to estimate rumen microbial protein synthesis. Data from three digestibility trials conducted with castrated male lambs fed ryegrass (Lolium multiflorum, Lam) or Cynodon (Cynodon dactylon var dactylon) at different levels of intake were compiled. Intake data were related to faecal excretion of different chemical compounds through regression analysis. Significant regressions with high R2 were used to calculate estimated intake values, which were compared to observed values by paired t test. Organic matter (OM) intake (g/day) had significant (P<0.01) relation to faecal excretion (g/day) of N and/or acid detergent fiber (ADF) in ryegrass trial (R2 varied from 0.69 to 0.85) while N, ADF and neutral detergent fiber (NDF) had significant (P<0.01) relation to OM intake in Cynodon trials (R2 varied from 0.51 to 0.56). It is concluded that faecal excretion of N and/or ADF had high potential to estimate intake by grazing animals. Rumen microbial protein synthesis estimated either by duodenal purines or urine purines derivatives was different (P<0.01). Moreover, these estimates were highly affected by purines:microbial N proportion used in calculations. / O objetivo deste trabalho foi avaliar métodos em nutrição de ruminantes: o uso de índices fecais para estimar consumo e uso de purinas no duodeno ou de derivados de purinas na urina para estimar a síntese de nitrogênio microbiano ruminal. Foram compilados dados de três ensaios de digestibilidade in vivo utilizando ovinos machos castrados não fistulados ou fistulados no duodeno alimentados com azevém (Lolium multiflorum, Lam) ou capim-paulista (Cynodon dactylon var dactylon) fornecidos verde a diferentes níveis de consumo. Os dados de consumo foram relacionados à excreção fecal de diferentes componentes químicos. As equações de regressão com coeficientes de correlação mais significativos foram utilizadas para calcular consumos estimados, os quais foram comparados pelo teste t para dados pareados com os consumos observados. O consumo de MO foi significativamente (P<0,01) relacionado com a excreção fecal de N e/ou fibra em detergente ácido (FDA) no ensaio com azevém (R2 variou de 0,69 a 0,85) e com a excreção fecal de N, FDA ou fibra em detergente neutro (FDN) nos ensaios com Cynodon (R2 variou de 0,51 a 0,56). Conclui-se que a excreção fecal de FDA e/ou N tem um alto potencial para estimar consumo por animais em pastejo. A síntese de nitrogênio microbiano ruminal estimado pela metodologia das purinas duodenais ou dos derivados de purinas excretados na urina não foi similar (P<0,01). Adicionalmente, estas estimativas foram altamente influenciadas pela relação purinas:N microbiano utilizada nos cálculos.