Dietary inclusion of sufficient lysine is very critical for optimizing pig’s growth performance. The objectives of this project were to study the effects of dietary lysine at different concentrations on (1) the growth performance and carcass characteristics, (2) the muscle gene expression profile and the possible alterations to the metabolic and signaling pathways, (3) the muscle fatty acid profile, and (4) the plasma concentrations of growth-related hormones of late-stage finishing pigs. Nine crossbred barrows were assigned to 3 dietary treatments (lysine-deficient, equate, and -excess diets) according to a completely randomized experimental design. During the 5-week feeding trial, pigs were allowed ad libitum access to experimental diets and water. All pigs and experimental diets were weighed individually each week during feeding trial to determine growth performance. After harvest, the carcass characteristics were determined and muscle samples were collected from longissimus dorsi for mRNA and fatty acid profiling, while the jugular vein blood was collected at the end of four weeks for analyses of three growth-related hormones. While the average daily gain showed a quadratic relationship, the dressing percentage and total lean cut weight both increased linearly with dietary lysine concentrations. Results of muscle gene expression data showed that dietary lysine deficiency may lead to decreased protein synthesis, increased protein degradation and lipid accumulation, while dietary lysine excess may lead to decreased protein degradation and increased lipid biosynthesis. Fatty acid (FA) composition data showed that different dietary lysine concentrations altered the intramuscular fat (IMF) content and FA composition, especially the unsaturated FAs. In particular, dietary lysine deficiency increased the IMF content and the proportion of mono-unsaturated FAs. Hormone analyses showed that the plasma concentrations of insulin and growth hormone were not affected by dietary lysine, whereas the concentration of insulin-like growth factor 1 was decreased by either dietary lysine deficiency or excess. Collectively, lysine may function as a signaling molecule to regulate the expression of genes related to protein turnover and lipid metabolism in the muscle of finishing pigs, causing differences in growth performance, carcass characteristics, and FA composition. IGF-1 may be a controlling growth factor that is sensitive to dietary lysine.

The objective of this study was to determine the effects of feeding endophyte-infected tall fescue seed to Angus steers on average daily gain, carcass characteristics, ergovaline concentration, lipid oxidation, hepatic enzyme activity, metmyoglobin reductase activity, and mitochondrial lipid composition. Animals were blocked into light, medium, and heavy body weight groups and were randomly assigned to either a KY31 seed treatment (6796 ppb ergovaline; 20 MUg/kg BW; E+; n = 6) or a KY32 control (< 100 ppb; E-; n = 6). There was a 2-way treatment × time interaction effect on ADG (P < 0.001). The E+ steers gained 0.56 kg/d less than the E- steers from d 0 to 14 (P < 0.001) until d 56 (ADG difference = 0.27 kg/d; P = 0.007) but both group had similar ADG from d 70 till the end of the feeding period 2 (ADG = 0.53 kg/d; P > 0.070). No difference in carcass characteristics were found between the E+ and E- steers by at the time of ultrasonography (P >= 0.120) or at harvest (P >= 0.199). In both period 1 and 2, there was a 2-way treatment × time interaction for ergovaline concentration in blood (P = 0.002 and 0.022, respectively). Infected tall fescue seed did not change d-3 hepatic enzyme activity in both feeding periods (P = 0.149 to 0.645). In period 1, thiobarbituric acid reactive substances, primarily consisting of malondialdehyde (MDA), were greater in blood serum of E+ steers than E- steers (6.56 MUM vs. 2.56 MUM; P = 0.048). An overall increase in MDA from d 0 (2.39 MUM) to d 3 (7.59 MUM) was also observed (P = 0.049). There was no effect of endophyte infected tall fescue seed on metmyoglobin reductase in longissimus thoracis (4.82 MUM/min/g in E- muscle vs. 3.93 MUM/min/g in E+ muscle; P = 0.484. There was no treatment effect on mitochondrial lipid composition (P >= 0.094), including phospholipids and fatty acids.

Dois experimentos foram realizados com o objetivo de avaliar a eficácia da suplementação de diferentes misturas de extratos vegetais nas rações de frangos de corte como melhoradores do desempenho. Para o ensaio de desempenho, foram utilizados 1350 pintos de corte em blocos casualizados, com 6 repetições e 5 dietas experimentais: CN - controle negativo (dieta basal); CP - controle positivo, CN com 10 ppm de avilamicina; ME1 - CN com produto contendo 200 ppm de óleos essenciais de cravo, tomilho, canela e pimenta; ME2- CN com 100 ppm do produto comercial composto por óleos essenciais sintéticos de orégano e canela e óleoresina de pimenta microencapsulados; ME3 CN 500 ppm do produto comercial constituído por óleo de eucalipto, óleo essencial de canela-da-China, folhas de boldo-do-Chile e sementes de feno-grego, na fase inicial e 1200 ppm nas fases de crescimento e final. As aves foram criadas em cama reutilizada com a finalidade de proporcionar desafio à criação. Foram realizadas análises de contagem de oocisto de Eimeria na cama antes do início e após o término do experimento e os exames das amostras de cama não revelaram presença de oocistos de Eimeria. Ganho de peso, consumo de ração, conversão alimentar, viabilidade, uniformidade do lote aos 42 dias de idade e características de carcaça foram avaliados. Aos 23 dias de idade, 80 frangos criados separadamente e submetidos aos mesmos tratamentos do experimento de desempenho foram transferidos para gaiolas de metabolismo e, dos 27 aos 30 dias de idade, foi realizado o ensaio de metabolismo pelo método de coleta total de excretas e determinados a energia metabolizável e o coeficiente de digestibilidade da proteína bruta das dietas. Quatro aves de cada tratamento, criadas separadamente, foram sacrificadas para realização da morfometria do proventrículo, moela, fígado, pâncreas e intestino delgado. Também foi anotado o comprimento do intestino delgado. As análises estatísticas foram realizadas no programa estatístico SAS e, no caso de diferença significativa, as médias comparadas pelo teste de Dunnett. As inclusões de misturas de extratos vegetais nas dietas de frangos de corte não foram capazes de exercer efeito significativo (P<0,05) quando comparadas às dietas controles CN e CP. Tal fato pode estar relacionado com a ausência de desafio nas condições experimentais aliado à utilização de dietas com ingredientes de alta digestibilidade que permitiram que os frangos de corte expressassem todo o seu potencial tornando indetectável qualquer melhora ocasionada pela inclusão de antibiótico ou de misturas de extratos vegetais nas dietas. Conclui-se que, nas condições em que foi realizado este estudo, as dietas contendo misturas de extratos promoveram desempenho semelhante ao das dietas CN e CP. / Two trials were carried out to evaluate different blends of plants extracts in broilers diets. Dietary treatments were fed to 1,350 one-day-old male Cobb chicks distributed in a randomized complete block design with six repetitions. The experimental diets were: NC - negative control (basal diet); PC - positive control, NC with 10 ppm of avilamycin; BPE1 - NC with 200 ppm of a blend containing natural essential oils of clove, thyme, cinnamon and capsicum microencapsulated; BPE2 - NC with a commercial product containing 100 ppm of synthetic cinnamaldehyde and carvacrol and natural capsicum oleoresin microencapsulated; BPE3 - NC with 500 ppm of commercial product containing eucalypt oil, essential oil of Chinese cinnamon, leaves of Chilene boldo and seeds of fenu-Greek in the initial phase and 1200 ppm in the grower and finisher phases. The amount of Eimeria oocist in the litter was analyzed before and after the trials and the results were negative to the presence of Eimeria oocist. Weight gain, feed intake, feed conversion, viability, uniformity at 42 days of age and carcass characteristics were evaluated. At 23 days of age, 80 chickens, raised at the same conditions and receiving the same diets as the chickens from the performance trial, were transferred to metabolic cages in a randomized complete block design and four repetitions. From 27 to 30 days of age, the total excreta collection method was applied to determine the apparent metabolizable energy and the crude protein digestibility of the dietary treatments. Four chickens from each treatment were sacrificed to evaluate relative weight of proventriculus, gizzard, liver, pancreas and small intestine. The length of the small intestine was also determined. The statistical analyses were carried out by SAS and the means were compared using the Dunnet test. The dietary utilization of plants extracts had no effect on parameters evaluated when compared to NC or PC. Possibly, the lack of challenge at poultry house and the high digestibility of the experimental diets made undetectable any improvement that could be shown by the inclusion of additives in the diet. It can be concluded that in these experimental conditions, the chickens fed on BPE1, BPE2 or BPE3 diets showed the same performance than NC or PC diets.

Este trabalho foi desenvolvido para avaliar o efeito da inclusão de níveis de volumoso (0, 5 e 12% da MS) em dietas de milho grão inteiro duro, para bovinos Nelore confinados. Cento e oito bovinos foram distribuídos em 18 baias (6 animais por baia) de acordo com o peso inicial (bloco) em um delineamento em blocos casualizados com três tratamentos e seis repetições (piquete). Os tratamentos utilizados foram: MGI - dieta milho grão inteiro mais o concentrado mineral proteico (CGI) - dieta controle; MGI5 - dieta controle com 5% de inclusão de volumoso (feno picado); MGI12 - dieta controle com 12% de inclusão de volumoso. Nas dietas contendo volumoso, a inclusão foi feita pela substituição pelo grão do milho. Foram avaliados o ganho médio diário (GMD), ingestão de matéria seca (IMS), eficiência alimentar (EA), consumo de nutrientes, características de carcaça avaliadas por ultrassom, além do peso (PCQ) e rendimento (RCQ) de carcaça quente e viabilidade econômica. Os animais do tratamento MGI tiveram menor peso final (505 kg; P&lt;0,05) em comparação aos tratamentos MGI5 e MGI12 (552 e 546 kg, respectivamente), que não diferiram entre si. A IMS foi maior no tratamento MGI12 (9,4 kg MS/dia) em comparação ao tratamento MGI5 (8,5 kg MS/dia; P&lt;0,05) e ao tratamento MGI (6,5 kg MS/dia; P&lt;0,05). A IMS do tratamento MGI5 também foi maior que o tratamento MGI (P&lt;0,05). Não houve diferença no GMD entre os tratamentos MGI5 e MGI12 (1.406 e 1.327 g/dia, respectivamente), porém ambos foram maiores que o MGI (760 g/dia: P&lt;0,05). A EA foi maior no tratamento MGI5 (167 g GMD / kg IMS) em comparação aos tratamentos MGI e MGI12 (116 e 141 g GMD / kg IMS, respectivamente; P&lt;0,05). As características de carcaça avaliadas por ultrassom não foram influenciadas pelos tratamentos. Por outro lado, apesar do maior PCQ observado nos tratamentos MGI5 e MGI12 (301 e 296 kg; respectivamente) em comparação ao MGI (279 kg: P&lt;0,05), o RCQ foi maior nos animais do tratamento MGI (55,3%; P&lt;0,05) em comparação ao MGI5 e MGI12 (54,5 e 54,2, respectivamente). Com relação a viabilidade econômica, o tratamento MGI5 apresentou maior retorno econômico em relação aos demais. A inclusão de feno na dieta de grão de milho inteiro aumenta o desempenho de bovinos Nelore confiados e a viabilidade econômica da atividade. / This study was conducted to evaluate the effect of including roughage levels (0, 5 and 12% of dry matter - DM) on finishing feedlot whole corn grain diets for Nellore cattle. One hundred and eight Nellore were assigned to 18 pens (six animals per pen) according to the initial weight (block) in a randomized complete block design with three treatments and six replications (pen). The treatments were: MGI - control diet with whole corn grain plus protein-mineral concentrate (CGI); MGI5 - control diet with 5% of roughage (chopped hay); MGI12 - control diet with 12% of roughage. In diets containing roughage, the inclusion was made by replacing the whole corn grain. The average daily gain (ADG), dry matter intake (DMI), feed efficiency (FE), nutrient intake, ultrasound carcass characteristics, in addition to weight (HCW) and dressing percentage (DP) of carcass besides economic viability were evaluated. Animals of MGI had lower final weight (505 kg; P&lt;0.05) compared to MGI5 and MGI12 treatments (552 and 546 kg, respectively), which did not differ. The DMI was higher in the treatment MGI12 (9.4 kg DM / day) compared to MGI5 (8.5 kg DM / day; P &lt;0.05) and MGI (6.5 kg DM / day; P &lt;0.05) treatments. The IMS of MGI5 treatment was also higher then MGI (P &lt;0.05). There were no differences in ADG between MGI5 and MGI12 treatments (1.406 and 1.327 g / day, respectively), but both were higher than the MGI (760 g / day: p&lt;0.05)). The FE was higher in the treatment MGI5 (167 g ADG / kg DMI) compared to MGI and MGI12 and treatments (116 and 141 g GMD / kg DMI, respectively; P &lt;0.05). The carcass characteristics evaluated by ultrasound were not affected by treatments. Moreover, despite the highest HCW observed in the MGI5 and MGI12 treatments (301 and 296 kg, respectively) compared to the MGI (279 kg; p&lt;0.05), the DP of MGI treatment was greater (55.3%; P &lt;0.05) compared to MGI5 and MGI12 (54.5 and 54.2, respectively). Regarding to economic viability, the MGI5 treatment showed higher economic return than the others. The inclusion of roughage in the whole corn grain diet increases the performance of feedlot finished Nellore cattle and increases the economic viability of the activity.

The aim of this thesis was to investigate contrasting pasture management strategies on the foraging behaviour, pasture production, carcass characteristics, herbage intake, faecal gas emissions and methane emission by sheep grazing Italian ryegrass (Lolium multiflorum) pastures. The experiment was carried out in 2014 and 2015. The experimental design was a randomized complete block with four replicates and two grazing strategy treatments (traditional rotational stocking method – RT meaning pre- and post-grazing target heights of 25 and 5 cm, respectively and, “rotatinuous stocking” – RN with pre- and post-grazing target heights of 18 and 11 cm, respectively). The grazing management was based on a 1-day strip-grazing regime. Male castrated sheep were used. The actual average sward heights for the RN treatment were 17.9 and 11.1 cm (pre- and post-grazing, respectively) and 27.1 and 7.8 cm for the RT (pre- and post-grazing, respectively). The stocking period in 2014 was 146 and 140 days (RN and RT, respectively) and in 2015 it was 155 and 146 days (RN and RT, respectively). The diurnal animal activities (grazing, ruminating and resting time) did not differ between treatments, with average of 439.6, 166.9 and 85.0 minutes, respectively. The bite rate, feeding station per min and steps per min were greater at the RN than the RT treatment. Grazing time and bite rate were greater in the afternoon than morning in both treatments. Therefore, the daily herbage intake by sheep grazing Italian ryegrass was greater for the RN than the RT treatment (CHAPTER II). The herbage production in the RN was 28% higher than the RT treatment. Individual average daily gain and live weight gain per hectare were greater in the RN than the RT treatment (CHAPTER III). RN treatment presented greater final live weight, carcass and commercial cut weights from grazing sheep than RT treatment (CHAPTER IV). RN treatment had a faecal chemical quality greater than RT treatment, resulting in a greater daily nitrogen excretion per animal and greater faecal CH4 and N2O emissions (CHAPTER VI). The “rotatinuous stocking” (RN) was the better grazing management strategy for mitigation of CH4 emissions by sheep grazing Italian ryegrass, emitting 64% less CH4 per unit area and 170% less CH4 per unit of animal product than the traditional rotational stocking method (RT) (CHAPTER V).

Este trabalho foi desenvolvido para avaliar o efeito da inclusão de níveis de volumoso (0, 5 e 12% da MS) em dietas de milho grão inteiro duro, para bovinos Nelore confinados. Cento e oito bovinos foram distribuídos em 18 baias (6 animais por baia) de acordo com o peso inicial (bloco) em um delineamento em blocos casualizados com três tratamentos e seis repetições (piquete). Os tratamentos utilizados foram: MGI - dieta milho grão inteiro mais o concentrado mineral proteico (CGI) - dieta controle; MGI5 - dieta controle com 5% de inclusão de volumoso (feno picado); MGI12 - dieta controle com 12% de inclusão de volumoso. Nas dietas contendo volumoso, a inclusão foi feita pela substituição pelo grão do milho. Foram avaliados o ganho médio diário (GMD), ingestão de matéria seca (IMS), eficiência alimentar (EA), consumo de nutrientes, características de carcaça avaliadas por ultrassom, além do peso (PCQ) e rendimento (RCQ) de carcaça quente e viabilidade econômica. Os animais do tratamento MGI tiveram menor peso final (505 kg; P&lt;0,05) em comparação aos tratamentos MGI5 e MGI12 (552 e 546 kg, respectivamente), que não diferiram entre si. A IMS foi maior no tratamento MGI12 (9,4 kg MS/dia) em comparação ao tratamento MGI5 (8,5 kg MS/dia; P&lt;0,05) e ao tratamento MGI (6,5 kg MS/dia; P&lt;0,05). A IMS do tratamento MGI5 também foi maior que o tratamento MGI (P&lt;0,05). Não houve diferença no GMD entre os tratamentos MGI5 e MGI12 (1.406 e 1.327 g/dia, respectivamente), porém ambos foram maiores que o MGI (760 g/dia: P&lt;0,05). A EA foi maior no tratamento MGI5 (167 g GMD / kg IMS) em comparação aos tratamentos MGI e MGI12 (116 e 141 g GMD / kg IMS, respectivamente; P&lt;0,05). As características de carcaça avaliadas por ultrassom não foram influenciadas pelos tratamentos. Por outro lado, apesar do maior PCQ observado nos tratamentos MGI5 e MGI12 (301 e 296 kg; respectivamente) em comparação ao MGI (279 kg: P&lt;0,05), o RCQ foi maior nos animais do tratamento MGI (55,3%; P&lt;0,05) em comparação ao MGI5 e MGI12 (54,5 e 54,2, respectivamente). Com relação a viabilidade econômica, o tratamento MGI5 apresentou maior retorno econômico em relação aos demais. A inclusão de feno na dieta de grão de milho inteiro aumenta o desempenho de bovinos Nelore confiados e a viabilidade econômica da atividade. / This study was conducted to evaluate the effect of including roughage levels (0, 5 and 12% of dry matter - DM) on finishing feedlot whole corn grain diets for Nellore cattle. One hundred and eight Nellore were assigned to 18 pens (six animals per pen) according to the initial weight (block) in a randomized complete block design with three treatments and six replications (pen). The treatments were: MGI - control diet with whole corn grain plus protein-mineral concentrate (CGI); MGI5 - control diet with 5% of roughage (chopped hay); MGI12 - control diet with 12% of roughage. In diets containing roughage, the inclusion was made by replacing the whole corn grain. The average daily gain (ADG), dry matter intake (DMI), feed efficiency (FE), nutrient intake, ultrasound carcass characteristics, in addition to weight (HCW) and dressing percentage (DP) of carcass besides economic viability were evaluated. Animals of MGI had lower final weight (505 kg; P&lt;0.05) compared to MGI5 and MGI12 treatments (552 and 546 kg, respectively), which did not differ. The DMI was higher in the treatment MGI12 (9.4 kg DM / day) compared to MGI5 (8.5 kg DM / day; P &lt;0.05) and MGI (6.5 kg DM / day; P &lt;0.05) treatments. The IMS of MGI5 treatment was also higher then MGI (P &lt;0.05). There were no differences in ADG between MGI5 and MGI12 treatments (1.406 and 1.327 g / day, respectively), but both were higher than the MGI (760 g / day: p&lt;0.05)). The FE was higher in the treatment MGI5 (167 g ADG / kg DMI) compared to MGI and MGI12 and treatments (116 and 141 g GMD / kg DMI, respectively; P &lt;0.05). The carcass characteristics evaluated by ultrasound were not affected by treatments. Moreover, despite the highest HCW observed in the MGI5 and MGI12 treatments (301 and 296 kg, respectively) compared to the MGI (279 kg; p&lt;0.05), the DP of MGI treatment was greater (55.3%; P &lt;0.05) compared to MGI5 and MGI12 (54.5 and 54.2, respectively). Regarding to economic viability, the MGI5 treatment showed higher economic return than the others. The inclusion of roughage in the whole corn grain diet increases the performance of feedlot finished Nellore cattle and increases the economic viability of the activity.

The aim of this thesis was to investigate contrasting pasture management strategies on the foraging behaviour, pasture production, carcass characteristics, herbage intake, faecal gas emissions and methane emission by sheep grazing Italian ryegrass (Lolium multiflorum) pastures. The experiment was carried out in 2014 and 2015. The experimental design was a randomized complete block with four replicates and two grazing strategy treatments (traditional rotational stocking method – RT meaning pre- and post-grazing target heights of 25 and 5 cm, respectively and, “rotatinuous stocking” – RN with pre- and post-grazing target heights of 18 and 11 cm, respectively). The grazing management was based on a 1-day strip-grazing regime. Male castrated sheep were used. The actual average sward heights for the RN treatment were 17.9 and 11.1 cm (pre- and post-grazing, respectively) and 27.1 and 7.8 cm for the RT (pre- and post-grazing, respectively). The stocking period in 2014 was 146 and 140 days (RN and RT, respectively) and in 2015 it was 155 and 146 days (RN and RT, respectively). The diurnal animal activities (grazing, ruminating and resting time) did not differ between treatments, with average of 439.6, 166.9 and 85.0 minutes, respectively. The bite rate, feeding station per min and steps per min were greater at the RN than the RT treatment. Grazing time and bite rate were greater in the afternoon than morning in both treatments. Therefore, the daily herbage intake by sheep grazing Italian ryegrass was greater for the RN than the RT treatment (CHAPTER II). The herbage production in the RN was 28% higher than the RT treatment. Individual average daily gain and live weight gain per hectare were greater in the RN than the RT treatment (CHAPTER III). RN treatment presented greater final live weight, carcass and commercial cut weights from grazing sheep than RT treatment (CHAPTER IV). RN treatment had a faecal chemical quality greater than RT treatment, resulting in a greater daily nitrogen excretion per animal and greater faecal CH4 and N2O emissions (CHAPTER VI). The “rotatinuous stocking” (RN) was the better grazing management strategy for mitigation of CH4 emissions by sheep grazing Italian ryegrass, emitting 64% less CH4 per unit area and 170% less CH4 per unit of animal product than the traditional rotational stocking method (RT) (CHAPTER V).

Made available in DSpace on 2014-06-11T19:33:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-17Bitstream added on 2014-06-13T20:45:13Z : No. of bitstreams: 1 canesin_rc_dr_jabo.pdf: 538754 bytes, checksum: ff04afe88df47df73388089d0501780c (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo deste estudo foi avaliar o efeito da frequência de suplementação no comportamento ingestivo animal, ingestão e digestibilidade da matéria seca, desempenho e características da carcaça; além de verificar o efeito da frequência de suplementação na, fermentação ruminal, fluxo de nutrientes, eficiência de síntese microbiana e produção de metano ruminal de bovinos Nelore, mantidos em pastagem de Brachiaria brizantha cv Marandu, durante o período da seca. O suplemento foi fornecido diariamente, de segunda a sexta-feira e suspenso aos sábados e domingos e em dias alternados, na ordem de 1%; 1,4% e 2,0% do peso corporal, respectivamente. O suplemento foi composto de polpa cítrica, farelo de algodão e uréia. Os dados foram submetidos à análise de variância com medidas repetidas no tempo, pelo procedimento MIXED do SAS, e as médias foram comparadas através do teste de Tukey. A frequência de suplementação não influenciou o desempenho, o comportamento ingestivo animal, a ingestão de matéria seca, a eficiência de síntese microbiana e a produção de metano ruminal. Os meses do ano exerceram efeito na massa e composição química da forragem, no desempenho e na produção de metano de bovinos em pastejo. Foram verificadas interações significativas entre as frequências de suplementação e meses avaliados na digestibilidade da matéria seca, pH e concentração de nitrogênio amoniacal ruminal, e na produção de ácidos graxos de cadeia curta. As características de carcaça foram influenciadas pelas frequências de suplementação, no entanto, encontraram-se no limite desejável de acabamento. Desta forma, a redução da frequência de suplementação torna-se uma boa opção no sistema de suplementação, pois permite diminuir custos com suplemento e equipamentos. / The objective of this study was to evaluate the effect of supplementation frequency on behavior animal intake, dry matter intake, dry matter digestibility, performance and characteristics of the carcass; besides the effect of the supplementation frequency on the ruminal fermentation, flow of nutrients, microbial synthesis efficiency and ruminal methane production by Nellore steers grazing Brachiaria brizantha cv. Marandu pasture during dry season. The supplement was offered daily or from Monday to Friday or in alternate days, in the order of 1%, 1.4% and 2.0% of the body weight, respectively. This supplement was composed by citrus pulp, cottonseed meal and urea. The data were analyzed by analysis of variance (repeated measure in time), using the proc mixed procedure of SAS, and the averages were cooperated through Tukey test. The supplementation frequency did not influence the performance, behavior animal intake and dry matter intake, microbial synthesis efficiency and ruminal methane production. Months of the year affected the herbage mass and their chemical composition, performance and ruminal methane production of animals. They were verified significant interaction between supplementation frequency and months for dry matter digestibility, ruminal pH and concentration of ruminal ammonia nitrogen and short-chain fatty acids production. Carcass characteristics were influenced by the supplementation frequency, however, they were in the desirable limit of finish. This way, the reduction in the supplementation frequency became a good option in the production system, because of reducing costs and time with supplement and equipments.

Resumo: O objetivo deste estudo foi avaliar o efeito da frequência de suplementação no comportamento ingestivo animal, ingestão e digestibilidade da matéria seca, desempenho e características da carcaça; além de verificar o efeito da frequência de suplementação na, fermentação ruminal, fluxo de nutrientes, eficiência de síntese microbiana e produção de metano ruminal de bovinos Nelore, mantidos em pastagem de Brachiaria brizantha cv Marandu, durante o período da seca. O suplemento foi fornecido diariamente, de segunda a sexta-feira e suspenso aos sábados e domingos e em dias alternados, na ordem de 1%; 1,4% e 2,0% do peso corporal, respectivamente. O suplemento foi composto de polpa cítrica, farelo de algodão e uréia. Os dados foram submetidos à análise de variância com medidas repetidas no tempo, pelo procedimento MIXED do SAS, e as médias foram comparadas através do teste de Tukey. A frequência de suplementação não influenciou o desempenho, o comportamento ingestivo animal, a ingestão de matéria seca, a eficiência de síntese microbiana e a produção de metano ruminal. Os meses do ano exerceram efeito na massa e composição química da forragem, no desempenho e na produção de metano de bovinos em pastejo. Foram verificadas interações significativas entre as frequências de suplementação e meses avaliados na digestibilidade da matéria seca, pH e concentração de nitrogênio amoniacal ruminal, e na produção de ácidos graxos de cadeia curta. As características de carcaça foram influenciadas pelas frequências de suplementação, no entanto, encontraram-se no limite desejável de acabamento. Desta forma, a redução da frequência de suplementação torna-se uma boa opção no sistema de suplementação, pois permite diminuir custos com suplemento e equipamentos. / Abstract: The objective of this study was to evaluate the effect of supplementation frequency on behavior animal intake, dry matter intake, dry matter digestibility, performance and characteristics of the carcass; besides the effect of the supplementation frequency on the ruminal fermentation, flow of nutrients, microbial synthesis efficiency and ruminal methane production by Nellore steers grazing Brachiaria brizantha cv. Marandu pasture during dry season. The supplement was offered daily or from Monday to Friday or in alternate days, in the order of 1%, 1.4% and 2.0% of the body weight, respectively. This supplement was composed by citrus pulp, cottonseed meal and urea. The data were analyzed by analysis of variance (repeated measure in time), using the proc mixed procedure of SAS, and the averages were cooperated through Tukey test. The supplementation frequency did not influence the performance, behavior animal intake and dry matter intake, microbial synthesis efficiency and ruminal methane production. Months of the year affected the herbage mass and their chemical composition, performance and ruminal methane production of animals. They were verified significant interaction between supplementation frequency and months for dry matter digestibility, ruminal pH and concentration of ruminal ammonia nitrogen and short-chain fatty acids production. Carcass characteristics were influenced by the supplementation frequency, however, they were in the desirable limit of finish. This way, the reduction in the supplementation frequency became a good option in the production system, because of reducing costs and time with supplement and equipments. / Orientadora: Telma Teresinha Berchielli / Coorientador: Antonio de Vega Garcia / Coorientador: Ricardo Andrade Reis / Banca: Dante Pazzanese Duarte Lanna / Banca: Marco Antonio Alvares Balsalobre / Banca: Alexandre Amstalden Moraes Sampaio / Banca: Ana Claudia Ruggieri / Doutor

The aim of this thesis was to investigate contrasting pasture management strategies on the foraging behaviour, pasture production, carcass characteristics, herbage intake, faecal gas emissions and methane emission by sheep grazing Italian ryegrass (Lolium multiflorum) pastures. The experiment was carried out in 2014 and 2015. The experimental design was a randomized complete block with four replicates and two grazing strategy treatments (traditional rotational stocking method – RT meaning pre- and post-grazing target heights of 25 and 5 cm, respectively and, “rotatinuous stocking” – RN with pre- and post-grazing target heights of 18 and 11 cm, respectively). The grazing management was based on a 1-day strip-grazing regime. Male castrated sheep were used. The actual average sward heights for the RN treatment were 17.9 and 11.1 cm (pre- and post-grazing, respectively) and 27.1 and 7.8 cm for the RT (pre- and post-grazing, respectively). The stocking period in 2014 was 146 and 140 days (RN and RT, respectively) and in 2015 it was 155 and 146 days (RN and RT, respectively). The diurnal animal activities (grazing, ruminating and resting time) did not differ between treatments, with average of 439.6, 166.9 and 85.0 minutes, respectively. The bite rate, feeding station per min and steps per min were greater at the RN than the RT treatment. Grazing time and bite rate were greater in the afternoon than morning in both treatments. Therefore, the daily herbage intake by sheep grazing Italian ryegrass was greater for the RN than the RT treatment (CHAPTER II). The herbage production in the RN was 28% higher than the RT treatment. Individual average daily gain and live weight gain per hectare were greater in the RN than the RT treatment (CHAPTER III). RN treatment presented greater final live weight, carcass and commercial cut weights from grazing sheep than RT treatment (CHAPTER IV). RN treatment had a faecal chemical quality greater than RT treatment, resulting in a greater daily nitrogen excretion per animal and greater faecal CH4 and N2O emissions (CHAPTER VI). The “rotatinuous stocking” (RN) was the better grazing management strategy for mitigation of CH4 emissions by sheep grazing Italian ryegrass, emitting 64% less CH4 per unit area and 170% less CH4 per unit of animal product than the traditional rotational stocking method (RT) (CHAPTER V).