Horses consume large amounts of fiber in their diet, which may affect digestibility and digesta rate of passage. The objective of these studies was to assess the effects of diet composition on digestibility and rate of passage in horses using mathematical models. Using previously published data, forage dry matter digestibility (DMD) was related to forage neutral detergent fiber (NDF) concentrations and crude protein (CP) concentrations (DMD = 66.1178 – 0.3410*NDF + 0.6356*CP, DM basis; P < 0.001). In a second experiment, horses were fed diets formulated to have high fiber (HF, n= 3; NDF = 55.3%, CP = 11.8%) or low fiber (LF, n = 3; NDF = 40.5%, CP = 13.3%) concentrations. The LF treatment had greater DM, organic matter, and gross energy digestibilities (P < 0.05), whereas the HF treatment had greater NDF digestibility (P < 0.05). Mathematical models were useful to determine mean retention time (MRT) and there were no differences between model MRT and algebraic MRT, or treatment. Some compartmental parameters were different between treatments (P < 0.05), indicating that dietary fiber may alter some components of digesta passage in horses.

Doctor of Philosophy / Department of Animal Sciences and Industry / Michael D. Tokach / Eleven experiments using 5,434 growing-finishing pigs were performed in addition to the development of a model to predict dietary NE that yields the greatest economic benefit. Two experiments were conducted to determine the effect of dietary phytogenics on growth and carcass performance of growing-finishing pigs. The addition of the combination of two phytogenics products (EOM 1+2) to diets improved ADFI, HCW, and carcass ADG. However, there was no evidence for treatment differences for growth or carcass performance in a second study. Two experiments were conducted to determine the effects of feeding high SID Trp:Lys ratios with and without Ractopamine HCl (RAC) on growth and carcass characteristics of finishing pigs. In Exp. 1, whereas increasing SID Trp:Lys ratio above 20% improved growth and carcass performance when diets contained RAC, pigs fed SID Trp:Lys ratios above 20% in diets without RAC had reduced growth and carcass performance. Contrary in Exp. 2, pigs fed increasing SID Trp:Lys in diet containing RAC did not provide further performance benefits. Three experiments were conducted to determine the optimum dietary SID Lys and CP concentrations in finishing pigs over 100 kg. The SID Lys requirement to obtain 100% of maximum response was 0.55 to 0.63% depending on the response variable. Growth and carcass performance was maximized in diets containing at least 12% dietary CP. Four experiments were conducted to determine the effects of SBM concentration and whether dEB, choline, or K are the reasons that performance is reduced when pigs over 100 kg BW are fed low CP diets. Performance was reduced as SBM concentration was reduced in the diet. Choline, K, and dEB do not appear to be the reason that performance is reduced when SBM concentration is decreased in low CP diets fed to pigs over 100 kg BW. A Microsoft Excel®-based model to predict the value of dietary NE that yields the greatest economic return to the production system was developed. Furthermore, a meta-analysis was conducted to incorporate the impact of NDF on carcass yield in the model.

Quatro bubalinos e quatro bovinos adultos com fístulas ruminais foram utilizados com o objetivo de se estudar os efeitos de diferentes níveis de fibra em detergente neutro na dieta sobre as características de fermentação e digestão ruminal. Foram avaliadas os seguintes parâmetros: degradabilidades da matéria seca, proteína bruta, fibra em detergente neutro do feno de Coast-cross e do farelo de trigo; matéria seca e, proteína bruta do milho em grãos moídos e do farelo de soja; digestibilidade com marcador (Cr2O3); concentração de amônia, produção de ácidos graxos voláteis (acético, propiônico e butírico) e pH do líquido ruminal. Os animais foram delineados em dois Quadrados Latinos (4x4) com arranjo fatorial 4x2 sendo quatro níveis crescentes de FDN na MS (54, 60, 66 e 72%) e duas espécies (bubalinos e bovinos). Cada subperíodo compreendeu 29 dias, sendo 13 de adaptação. Observou-se um efeito significativo (P<0,01) da espécie sobre o pH ruminal, onde os bubalinos apresentaram valor médio (6,78) mais elevado que os bovinos (6,58). Houve efeito da interação tempo x espécie, na concentração de amônia do líquido ruminal somente após 2 horas da alimentação da manhã, onde os bubalinos obtiveram média de 31,76 mg% e os bovinos de 27,74 mg%. Os bubalinos mostraram valores de concentração média de ácidos graxos voláteis, ácido acético e ácido butírico (69,94 mM, 51,31 mM e 6,12 mM) menor (P<0,05) que a dos bovinos (77,96 mM, 56,72 mM e 8,01 mM). Não houve diferença significativa (P>0,05) na concentração de ácido propiônico e na relação acético:propiônico, não sofrendo influência de nenhum dos parâmetros principais analisados. Os bubalinos apresentaram maior desaparecimento ruminal da MS e FDN do feno de Coast-cross e da MS e PB do farelo de soja do que os bovinos, na maioria dos tempos de incubação. O desaparecimento ruminal da PB do feno de Coast-cross foi maior para os bubalinos somente nas últimas horas de incubação. Por outro lado, o desaparecimento ruminal da FDN do farelo de trigo foi mais elevado para os bovinos, somente nas primeiras horas. Para o coeficiente de digestibilidade da MS, houve interação de espécies com níveis de FDN. O coeficiente de digestibilidade da FDN foi influenciada pelos níveis de FDN e para o coeficiente de digestibilidade da PB, não foram notados efeitos de espécies ou níveis de FDN. / Four buffaloes and four cattle rumen fistulated, were used to study the effects of different levels of neutral detergent fiber in the diet on the rumen fermentation and digestion. In situ degradability assay was make of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) of the Coast-Cross hay (Cynodon dactylon) and the concentrate mixture; digestibility with marker (Cr2O3); ammonia concentration, production of volatile fatty acids (acetic, propionic and butyric) and pH in the ruminal liquid. The animals were designed in two Latin Square experiment (4x4). Treatments were applied in factorial 4 x 2 with four rations with increasing levels of NDF (54, 60, 66 and 72%) and two animal species (buffaloes and cattle). Twenty-nine days subperiods were used, the first thirteen for diet's adaptation. A significant effect was observed (P<0,01) in the species on the ruminal pH, with average of 6.78 in buffaloes and of 6.58 in cattle. There was effect of the interaction time x species, in the rumen ammonia concentration only at 2 hours after feeding with buffaloes having mean of 31.76 mg% and cattle 27.74 mg%. Buffaloes had lower (P<0,05) concentration of volatile fatty acids, acid acetic and acid butyric (69.94 mM, 51.31 mM and 6.12 mM) than cattle (77.96 mM, 56.72 mM and 8.01 mM). There was no significant difference (P>0,05) acid propionic concentration and acetic:propionic relation. The buffaloes showed higher ruminal disappearance of DM and NDF of the Coast-cross hay and DM and CP of the soybean meal than the cattle, in most of the times of incubation. The ruminal disappearance of CP of Coast-cross hay went higher for the buffaloes only in the last hours of incubation. On the other hand, the ruminal disappearance of NDF of wheat bran went higher for the cattle only in the first hours. There was interaction of species with levels of NDF for digestibility coefficient of the DM. The digestibility coefficient of NDF was only influenced by the levels of NDF. The digestibility coefficient of CP wasn't noticed effects of species or levels of NDF.

Made available in DSpace on 2014-06-11T19:27:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-06Bitstream added on 2014-06-13T20:36:08Z : No. of bitstreams: 1 ribeiro_ms_me_botfmvz.pdf: 174069 bytes, checksum: 2dd52fa6a3e9b9232005ba7edbfded45 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / The objective of this paper was to compare dried corn plant (DCP) as a roughage (R) source for lactating goats to roughages traditionally used for feeding ruminants: alfalfa hay (AH) and coastcross hay (CCH). Twenty-one crossbred goats weighing an average of 66.48 kg were used. After reaching their lactation peak, they were distributed among seven 3 x 3 latin squares. Each experimental diet consisted of one of the roughages fed ad lib plus a commercial concentrate (C) for lactating goats, fed on a basis of 1 kg for every 2.5 kg of milk. Each group, composed by seven animals kept in a collective pen with slatted floor, stayed in each treatment for two weeks; the first week was an adaptation period, whereas milk yield measurements and milk samples were collected during the second week. Dry or as-fed matter intake was higher in AH than in DCP or CCH. No treatment effect on C intake was detected. The higher dry matter intake in AH led to higher intakes of crude protein, ether extract, minerals, nitrogen-free extract, total digestible nutrients and acid detergent fiber, both in R and in the total diet (R + C). No treatment effect was observed for either crude fiber or neutral detergent fiber intakes in R and in R+C. Milk yield and milk PB content were higher in AH than in DCP or CCH; however, milk yield corrected for 3.5% fat and body weight loss were higher in AH than in CCH, but DCP did not differ from the other two treatments. Production cost per kg of milk was lower for DCP than for AH or CCH. The results show that DCP is a valid alternative roughage for dairy goats.

Made available in DSpace on 2015-03-26T13:54:50Z (GMT). No. of bitstreams: 1 texto completo.pdf: 526815 bytes, checksum: 0f1a8d5fba2922105d942fb71cd87da7 (MD5) Previous issue date: 2010-02-23 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this work was to evaluate the lignin contents in tropical forage using the methods of acid sulfuric lignin (ASL), potassium permanganate lignin (PL), Klason lignin (KL) and acetyl bromide soluble lignin obtained from cell wall (ABLcw) and from acid detergent residue (ABLad) and their association with parameters of neutral detergent fiber (NDF) degradation. It were evaluated ten grass samples: elephant grass (Pennisetum purpureum), signal grass (Brachiaria decumbens), torpedo grass (Panicum repens), Korovinia grass (Brachiaria humidicula), gamba grass (Andropogon gayanus), aruana grass (Panicum maximum cv. Aruana), mombaça grass (Panicum maximum cv. Mombaça), xaraés grass (Brachiaria brizantha cv. Xaraés), tifton-85 (Cynodon sp.), and massai grass (Panicum maximum cv. Massai); and ten legume samples: perennial peanut (Arachis pintoi), alfafa (Medicago sativa), leucaena (Leucaena leucocephala), galactia (Galactia striata), lablab bean (Dolichos lablab), butterfly pea (Centrosema pubescens), glycine (Glycine weghtii), gliricidia (Gliricidia sepium), Brazilian lucerne (Stylosantes guianenensis) and guandu (Cajanus cajan). All samples were taken through a cutting near to ground in December of 2008. The plants were 45-days regrowth. The lignin contents obtained by gravimetric methods were also estimated corrected for nitrogenous compounds. In this case, they were assigned as ASLp, PLp, and KLp. The indigestible NDF (iNDF), the fractional degradation rate of potentially degradable NDF (kd), and the discrete lag of NDF degradation were obtained by an in vitro assay. The correction for nitrogenous compounds decreased (P<0.05) the contents of ASL, KL and PL. The differences between corrected and crude values were more prominent for KL. The protein contents of KL were found similar (P>0.05) to neutral detergent insoluble protein. There was interaction effect (P<0.05) between analytical method and forage group on lignin contents. Considering the contents as g/kg DM, differences between grasses and legumes were pointed out (P<0.05) by ASLp and PLp, being the higher values associated with legumes, and by ABLcw, which caused higher values in grasses. For grasses, highest lignin contents (P<0.05) were obtained with KLp, which was followed by PLp and ABLcw, that did not differ each other (P>0.05), ASLp, and ABLad. For legumes, highest contents (P<0.05) were obtained with KLp, followed by LPp, ASLp, ABLcw, and ABLad. These last two were not different (P>0.05). The lignin estimates obtained by ASLp and PLp shown similar association pattern (P<0.05) with iNDF, kd, and LAG. There was no difference in both methods for grasses and legumes regarding intercept and slope of adjusted regression (P>0.05). Stronger correlations were observed between PLp and degradation parameters of NDF compared to ASLp. The KLp estimates did associate with alldegradation parameters (P<0.05). However, there were differences between grasses and legumes regardingintercept of adjusted regression (P<0.05). Legumes presented higher iNDF and LAG, and lower kd. The strongest correlation coefficients were obtained using LPp and KLp estimates. The ABLcw contents did not did not presented functional relationships with NDF degradation parameters (P>0.05), where only the average differences between forage groups were detected. It was verified relationship (P<0.05) between ABLad contents and iNDF. However, no difference between grasses and legumes was pointed out by adjusted regression (P>0.05). Nevertheless, the correlation coefficient was weaker compared to ones obtained using ASLp, KLp, and PLp. There were no functional relationships between ABLcw and degradation parameter of NDF (P>0.05). In this case, it was only detected the average difference between forage groups. It was concluded that gravimetric methods ASL, PL and KL produce residues that contain significant contaminant nitrogenous compounds. More accurate estimates of lignin content could be obtained when correction for residual nitrogen is done. This is particularly necessary for KL. Associations between lignin and degradation parameters of NDF are better recognized when KLp and PLp methods are employed. / Objetivou-se avaliar os teores de lignina em forragens tropicais pelos métodos lignina em ácido sulfúrico (LAS), lignina em permanganato de potássio (LPER), lignina Klason (LK) e lignina solúvel em brometo de acetila obtida a partir da parede celular (LBApf) e do resíduo em detergente ácido (LBAfda) e sua associação com parâmetros da degradação da fibra em detergente neutro (FDN). Foram avaliadas amostras de dez gramíneas: capim elefante (Pennisetum purpureum), capim braquiária (Brachiaria decumbens), grama castela (Panicum repens), quicuio da amazônia (Brachiaria humidicola), capim andropogon (Andropogon gayanus), capim aruana (Panicum maximum cv. Aruana), capim mombaça (Panicum maximum cv. Mombaça), capim xaraés (Brachiaria brizantha cv. Xaraés), capim tifton-85 (Cynodon sp.) e capim-massai (Panicum maximum cv. Massai); e dez leguminosas: amendoim forrageiro (Arachis pintoi), alfafa (Medicago sativa), leucena (Leucaena leucocephala), galactia (Galactia striata), lab lab (Dolichos lablab), centrosema (Centrosema pubescens), soja perene (Glycine weghtii), gliricidia (Gliricidia sepium), estilosantes (Stylosantes guianenensis) e guandu (Cajanus cajan). Todas as amostras foram obtidas por corte rente ao solo no mês de dezembro de 2008. As plantas apresentavam aproximadamente 45 dias de rebrotação. Os teores de lignina obtidos pelos métodos gravimétricos foram estimados também na forma corrigida para compostos nitrogenados, sendo referenciados como LASp, LPERp e LKp. Foram estimados por intermédio de ensaio in vitro os teores da fração indegradável da FDN (FDNi), a taxa de degradação da fração potencialmente degradável da FDN (kd) e a latência discreta para degradação da FDN (LAG). A correção para compostos nitrogenados implicou reduções significativas (P<0,05) nos teores de LAS, LK e LPER. Evidenciaram-se diferenças mais proeminentes entre valores corrigidos e brutos (não corrigidos) para LK. Os teores de proteína associados à LK foram considerados similares (P>0,05) aos teores de proteína insolúvel em detergente neutro. Verificou-se interação (P<0,05) entre método analítico e grupo de forrageiras para os teores de lignina. Considerando-se a unidade g/kg MS, diferenças entre gramíneas e leguminosas foram obtidas (P<0,05) com os métodos LASp e LPERp, que indicaram maiores valores para leguminosas, e LBApc, o qual, por sua vez, indicou maior estimativa para gramíneas. Considerando-se somente gramíneas, maior estimativa (P<0,05) foi conferida pelo método LKp, seguido de LPERp e LBApc, que não diferiram (P>0,05), LASp e LBAfda. Para leguminosas, as maiores estimativas (P<0,05) foram conferidas por LKp, seguidas por LPERp, LASp e LBApc e LBAfda, sendo estes últimos similares (P>0,05). As estimativas dos teores de lignina obtidas pelos métodos LASp e LPERp apresentaram comportamento similar, associando-se significativamente (P<0,05) com os teores de FDNi e com kd e LAG. Contudo, para ambos os métodos, não se detectou comportamento diferenciado para gramíneas e leguminosas quanto ao intercepto ou coeficiente de inclinação da função ajustada (P>0,05). Correlações mais fortes foram observadas entre LPERp e os parâmetros de degradação da FDN em relação àquelas obtidas com o método LASp. Os teores de LKp se associaram (P<0,05) com todos os parâmetros de degradação da FDN. No entanto, diferente dos métodos LASp e LPERp, verificou-se diferenciação entre gramíneas e leguminosas quanto ao intercepto da função ajustada (P<0,05), observando-se valores superiores de FDNi e LAG e inferiores de kd para as leguminosas. Os mais fortes coeficientes de correlação entre todos os métodos avaliados foram obtidos com LPERp e LKp. Os teores de lignina estimados pelo método LBApc não apresentaram relação (P>0,05) funcional com nenhum dos parâmetros da dinâmica de degradação da FDN. Para todos estes, apenas percebeu-se a diferença média entre grupos de forrageiras. Verificou-se relação (P<0,05) entre os teores de lignina estimados pelo método LBAfda e os teores de FDNi, observando-se, contudo, nenhuma diferenciação entre gramíneas e leguminosas (P>0,05). Contudo, o coeficiente de correlação foi menos forte em comparação àqueles verificados para os métodos LASp, LKp e LPERp. Não foram verificadas relações funcionais (P>0,05) entre as estimativas obtidas pelo método LBApc e os parâmetros de degradação da FDN, detectando-se somente a diferença média entre grupos de forrageiras. A partir dos resultados obtidos conclui-se que os métodos gravimétricos LAS, LPER e LK produzem resíduos contaminados por compostos nitrogenados. A correção para estes contaminantes é sugerida, notadamente para LK, para que os teores de lignina sejam expressos com maior exatidão. Associações entre lignina e os parâmetros de degradação ruminal da FDN são mais bem estabelecidas utilizando-se as estimativas produzidas pelos métodos LKp e LPERp.

Orientador: Heraldo César Gonçalves / Abstract: The objective of this paper was to compare dried corn plant (DCP) as a roughage (R) source for lactating goats to roughages traditionally used for feeding ruminants: alfalfa hay (AH) and coastcross hay (CCH). Twenty-one crossbred goats weighing an average of 66.48 kg were used. After reaching their lactation peak, they were distributed among seven 3 x 3 latin squares. Each experimental diet consisted of one of the roughages fed ad lib plus a commercial concentrate (C) for lactating goats, fed on a basis of 1 kg for every 2.5 kg of milk. Each group, composed by seven animals kept in a collective pen with slatted floor, stayed in each treatment for two weeks; the first week was an adaptation period, whereas milk yield measurements and milk samples were collected during the second week. Dry or as-fed matter intake was higher in AH than in DCP or CCH. No treatment effect on C intake was detected. The higher dry matter intake in AH led to higher intakes of crude protein, ether extract, minerals, nitrogen-free extract, total digestible nutrients and acid detergent fiber, both in R and in the total diet (R + C). No treatment effect was observed for either crude fiber or neutral detergent fiber intakes in R and in R+C. Milk yield and milk PB content were higher in AH than in DCP or CCH; however, milk yield corrected for 3.5% fat and body weight loss were higher in AH than in CCH, but DCP did not differ from the other two treatments. Production cost per kg of milk was lower for DCP than for AH or CCH. The results show that DCP is a valid alternative roughage for dairy goats. / Mestre

Quatro bubalinos e quatro bovinos adultos com fístulas ruminais foram utilizados com o objetivo de se estudar os efeitos de diferentes níveis de fibra em detergente neutro na dieta sobre as características de fermentação e digestão ruminal. Foram avaliadas os seguintes parâmetros: degradabilidades da matéria seca, proteína bruta, fibra em detergente neutro do feno de Coast-cross e do farelo de trigo; matéria seca e, proteína bruta do milho em grãos moídos e do farelo de soja; digestibilidade com marcador (Cr2O3); concentração de amônia, produção de ácidos graxos voláteis (acético, propiônico e butírico) e pH do líquido ruminal. Os animais foram delineados em dois Quadrados Latinos (4x4) com arranjo fatorial 4x2 sendo quatro níveis crescentes de FDN na MS (54, 60, 66 e 72%) e duas espécies (bubalinos e bovinos). Cada subperíodo compreendeu 29 dias, sendo 13 de adaptação. Observou-se um efeito significativo (P<0,01) da espécie sobre o pH ruminal, onde os bubalinos apresentaram valor médio (6,78) mais elevado que os bovinos (6,58). Houve efeito da interação tempo x espécie, na concentração de amônia do líquido ruminal somente após 2 horas da alimentação da manhã, onde os bubalinos obtiveram média de 31,76 mg% e os bovinos de 27,74 mg%. Os bubalinos mostraram valores de concentração média de ácidos graxos voláteis, ácido acético e ácido butírico (69,94 mM, 51,31 mM e 6,12 mM) menor (P<0,05) que a dos bovinos (77,96 mM, 56,72 mM e 8,01 mM). Não houve diferença significativa (P>0,05) na concentração de ácido propiônico e na relação acético:propiônico, não sofrendo influência de nenhum dos parâmetros principais analisados. Os bubalinos apresentaram maior desaparecimento ruminal da MS e FDN do feno de Coast-cross e da MS e PB do farelo de soja do que os bovinos, na maioria dos tempos de incubação. O desaparecimento ruminal da PB do feno de Coast-cross foi maior para os bubalinos somente nas últimas horas de incubação. Por outro lado, o desaparecimento ruminal da FDN do farelo de trigo foi mais elevado para os bovinos, somente nas primeiras horas. Para o coeficiente de digestibilidade da MS, houve interação de espécies com níveis de FDN. O coeficiente de digestibilidade da FDN foi influenciada pelos níveis de FDN e para o coeficiente de digestibilidade da PB, não foram notados efeitos de espécies ou níveis de FDN. / Four buffaloes and four cattle rumen fistulated, were used to study the effects of different levels of neutral detergent fiber in the diet on the rumen fermentation and digestion. In situ degradability assay was make of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) of the Coast-Cross hay (Cynodon dactylon) and the concentrate mixture; digestibility with marker (Cr2O3); ammonia concentration, production of volatile fatty acids (acetic, propionic and butyric) and pH in the ruminal liquid. The animals were designed in two Latin Square experiment (4x4). Treatments were applied in factorial 4 x 2 with four rations with increasing levels of NDF (54, 60, 66 and 72%) and two animal species (buffaloes and cattle). Twenty-nine days subperiods were used, the first thirteen for diet's adaptation. A significant effect was observed (P<0,01) in the species on the ruminal pH, with average of 6.78 in buffaloes and of 6.58 in cattle. There was effect of the interaction time x species, in the rumen ammonia concentration only at 2 hours after feeding with buffaloes having mean of 31.76 mg% and cattle 27.74 mg%. Buffaloes had lower (P<0,05) concentration of volatile fatty acids, acid acetic and acid butyric (69.94 mM, 51.31 mM and 6.12 mM) than cattle (77.96 mM, 56.72 mM and 8.01 mM). There was no significant difference (P>0,05) acid propionic concentration and acetic:propionic relation. The buffaloes showed higher ruminal disappearance of DM and NDF of the Coast-cross hay and DM and CP of the soybean meal than the cattle, in most of the times of incubation. The ruminal disappearance of CP of Coast-cross hay went higher for the buffaloes only in the last hours of incubation. On the other hand, the ruminal disappearance of NDF of wheat bran went higher for the cattle only in the first hours. There was interaction of species with levels of NDF for digestibility coefficient of the DM. The digestibility coefficient of NDF was only influenced by the levels of NDF. The digestibility coefficient of CP wasn't noticed effects of species or levels of NDF.

Tall fescue (Schedonorus arundinaceus), is a cool season perennial that provides grazing into the early summer months for southern livestock. Grazing the tall fescue variety, Kentucky-31, has negative effects on animal health, particularly after jointing. Two studies were arranged as randomized complete blocks in a split-plot design, with three replicates to compare: the effect of ten herbicides on seedhead suppression, or the effect of inter-seeding legumes [white clover (Trifolium repens) or alfafla (Medicago sativa)] coupled with nitrogen supplementation on fescue yield and forage nutritive value. The herbicides imazethapyr + 2,4-D and without, metsulfuron + chlorsulfuron, reduced seedheads emergence, but not yield compared to the control. Kentucky-31 inter-seeded with white clover and fertilized with 11 kg N ha-1 produced greater biomass than tall fescue fertilized with 11 kg N ha-1. The inter-seeding of white clover produced composite forage samples with greater in vitro dry matter disappearance than nitrogen supplemented alfalfa.

As pastagens ocupam uma grande extensão territorial no Brasil constituindo a principal fonte de alimento para os ruminantes. Entretanto, seu manejo, ainda é frequentemente realizado de forma extensiva e extrativista, tornando a atividade pouco competitiva. O estudo de estratégias de manejo do pastejo sob lotação contínua contribui para a diversificação e intensificação dos sistemas de produção de ruminantes baseados em pastagens. O objetivo foi descrever e explicar diferenças no potencial produtivo e nas características qualitativas, através de atributos estruturais e químico-bromatológicos da Brachiaria híbrida (Brachiaria ssp.) Convert HD 364 em resposta ao manejo do pastejo sob lotação contínua mimetizada e taxa de lotação variável. O experimento foi conduzido em Piracicaba, no verão de 2013. Foram testadas três intensidades de desfolhação determinadas por alturas de manejo de dossel (10, 25 e 40 cm) em combinação com dois ritmos de crescimento (50 e 250 kg N ha-1 ano-1) num arranjo fatorial (3 x 2) e delineamento em blocos completos casualizados. Variáveis-resposta medidas incluíram massa, acúmulo e taxa de acúmulo de forragem, IAF, composição morfológica e valor nutritivo (Proteína bruta - PB, Fibra insolúvel em detergente neutro- FDN, Digestibilidade in vitro da matéria orgânica - DIVMO) da forragem. Os maiores valores de acúmulo e taxa de acúmulo foram registrados para os dosséis mantidos a 40 cm de altura (12650 kg MS ha-1ano-1 e 110 kg MS ha-1 dia-1, respectivamente) e para dosséis adubados com 250 kg N ha-1(13974 kg MS ha-1ano-1 e 126 kg MS ha-1dia-1, respectivamente). Esse mesmo tratamento apresentou os maiores valores de IAFs (8,1). A massa de forragem não sofreu influência do N, mas respondeu ao aumento da altura e foi maior para os pastos mantidos a 40 cm (14650 kg MS ha-1). Mais N (250 kg ha-1) resultou em maior proporção de folhas (26 %). Maior proporção de colmo (40%) ocorreu no dosséis de 40 cm e adubados com 50 kg N ha-1 e proporções de material morto foram maiores (49%) nos tratamentos de 10 cm de altura e 50 kg de N ha-1. Dosséis de 10 cm adubados com 50 kg N ha-1, embora com menor produtividade, resultaram em maior DIVMO (670 g kg-1) e PB (153 g kg-1 e 165 g kg-1, para 10 cm e 250 kg N ha-1, respectivamente). O teor de FDN foi maior para 40 cm (545g kg-1) e com 50 kg N ha-1(550 g kg-1). A adubação nitrogenada promove ganhos em produtividade e resulta em forragem com melhor valor nutritivo, enquanto que incrementos em altura do dossel promovem maior acúmulo total e taxa média de acúmulo de forragem, até o ponto em que ocorre estabilidade da produção (25 cm), sendo assim o tratamento que apresentou melhor eficiência produtiva aliada a um bom valor nutritivo foi o com 25 cm de altura do dossel e 250 kg ha-1 de N. / Pastures occupy a large area in Brazil and are key to the country\'s livestock industry, which is almost exclusively forage-based. Grazing management, however, is largely empirical in the country, and technical guidelines for managing specific grasses are either scarce or poorly adopted, which hinders the competitiveness of the activity. Establishing sound management guidelines for key grasses can improve animal output and profitability of the livestock enterprise. The objective was to describe and explain differences in the productive potential and the qualitative traits of Convert HD 364 brachiariagrass through the characterization of agronomic and sward structural attributes as well as forage nutritive in response to three grazing intensities and under two growth rates under continuous stocking and variable stocking rate in a mob-grazing experimental protocol. The study was conducted in Piracicaba, in summer of 2013. Experimental paddocks received treatments corresponding to all possible combinations among three sward heights (10, 25, and 45 cm) and two growth rates generated by two N rates (50 and 250 kg N ha-1) split-applied monthly during the experimental period. The experimental design was a randomized complete block with a factorial arrangement. Response variables included forage accumulation and accumulation rate, LAI, plant-part composition of forage on offer, as well as plant-part composition and nutritive value (crude protein - CP, neutral detergent insoluble fiber - NDF digestibility in vitro organic matter - IVDMD) of forage. The highest values of forage accumulation and accumulation rate were recorded for swards kept at 40 cm (12650 kg DM ha-1 yr-1 and 110 kg ha-1 d-1, respectively) and for swards fertilized with 250 kg N ha-1 (13974 kg DM ha-1 yr-1 and 126 kg DM ha-1 day-1, respectively). This same combination resulted the highest LAI (8.1). Forage mass was affected by sward height but not by N rates being higher for 40-cm (14650 kg DM ha-1). Treatments with higher N (250 kg ha-1) resulted in forage with a higher proportion of leaf (26%). Higher percentages of stem (40%) were measured in swards grazed at 40 cm and fertilized with 50 kg N ha-1 while the proportion of dead material was higher (49%) in 10-cm swards receiving 50 kg N ha-1 of N. Swards kept at 10 cm and receiving 50 kg N ha-1, although less productive, resulted in forage with higher IVOMD (670 g kg-1). Forage in 10-cm swards had 153 g kg-1 crude protein and that from swards receiving 250 kg N ha-1 had 165 g kg-1. Neutral detergent fiber concentration was higher in forage from 40-cm swards (545 g kg-1) and from those receiving 50 kg N ha-1 (550 g kg-1), which is also associated with the maturity of the tissues at the time of harvest. Nitrogen fertilization promotes gains in productivity and results in forage with better nutritive value, whereas increases in canopy height promote higher total accumulation and rate of herbage accumulation, up to 25 cm. The treatment that combines high productivity with high nutritive value is 25 cm canopy height and 250 kg ha-1.

No experimento I, objetivou-se avaliar os efeitos de aditivos microbianos e tempo de armazenamento na qualidade de silagens de milho. A cultura do milho foi ensilada sem aditivos (Controle) ou com inoculantes contendo bactérias láticas homofermentativas (Lactobacillus plantarum + Enterococcus faecium + Pediococcus acidilactici) + enzimas celulolíticas e hemiceluloliticas ou heterofermentativas (Lactobacillus buchneri) aplicados na dose 1 × 105 ufc/g. As silagens foram armazenadas em silos experimentais durante 3, 7, 15, 30, 60, 210, 390, 480 ou 570 dias. Foram avaliados: composição químico-bromatológica, produtos de fermentação, perfil microbiológico, perdas fermentativas, estabilidade aeróbia e degradabilidade ruminal in situ. Os inoculantes não afetaram a maior parte das variáveis estudadas. Entretanto, L. buchneri aumentou a concentração de ácido acético das silagens e diminuiu a deterioração aeróbia, confirmada pelo menor acúmulo térmico durante o ensaio de estabilidade aeróbia. O teor de carboidratos solúveis diminuiu ao longo do tempo de armazenamento, reflexo do metabolismo dos açúcares em produtos de fermentação. As concentrações da prolamina como esperado diminuíram e as concentrações de nitrogênio amoniacal e proteína solúvel aumentaram com os tempos de armazenagem prolongados, reflexo da ocorrência de proteólise na silagem de milho. O pH da silagem diminuiu rapidamente nos primeiros sete dias de armazenamentos mantendo-se estável para os demais tempos de estocagem, diferente do ocorrido para a concentração de ácido acético, que aumentou com o tempo de armazenamento. Verificou-se diminuição na contagem de bactérias láticas e leveduras ao longo do armazenamento. A produção de gás e a perda de matéria seca aumentaram com o tempo de armazenamento. O tempo de armazenamento aumentou todas as variáveis de EA. Os ganhos mais significativos para a EA se deram até aproximadamente 60 dias de armazenamento. A degradação ruminal de amido e, consequentemente de MS, foi incrementada ao longo do armazenamento. No experimento II, objetivou-se avaliar o desempenho de vacas leiteiras em função da estratégia de descarregamento da silagem de milho em silo do tipo trincheira: silagem de milho oriunda da metade superior do silo (topo) ou silagem de milho oriunda da metade inferior do silo (base). Foram utilizadas 24 vacas alocadas em 12 blocos casualisados, com arranjo de reversão simples com períodos de 21 dias. Os animais foram alojados em confinamento tie-stall. As dietas foram iso-protéicas (16,5%) e iso-amiláceas (17,0%), com 60% de silagem de milho (% MS). O consumo de matéria seca, produção e composição do leite foram determinados entre os dias 15 e 21 de cada período experimental. Apesar da silagem oriunda da base do silo levar à maior digestibilidade da dieta e menor concentração de nitrogênio ureico do leite (8,95 e 11,35 mg/dL) não houve efeito da dieta no consumo de matéria seca nem na produção de leite. Sob condições ótimas de manejo, a estratégia de descarregamento da silagem de milho não afeta o desempenho de vacas leiteiras. / In the experiment I, the aim was to evaluate the effects of microbial additives and length of storage on the quality of corn silage. Whole-corn plants were ensiled without or with inoculants containing homofermentative (Lactobacillus plantarum + Enterococcus faecium + Pediococcus acidilactici + cellulolytic and hemicellulolytic enzymes) or heterofermentative lactic acid bacteria (Lactobacillus buchneri) applied at 1 × 105 cfu/g. Treated forages were packed and stored in experimental silos for 3, 7, 15, 30, 60, 210, 390, 480, and 570 days. Samples were evaluated for chemical composition, fermentation end-products, microbial counts, fermentation losses, aerobic stability, and ruminal degradability in situ. Inoculants did not affect most of the variables studied. However, L. buchneri increased acetic acid concentration and decreased aerobic deterioration of silages, as indicated by the lower heat accumulation during the exposure to air. Soluble carbohydrates decreased across the storage period, reflecting the conversion of soluble sugars to fermentation end-products. Concentrations of prolamin decreased, whereas ammonia and soluble protein concentrations increased over the storage period, indicating the proteolysis. The silage pH declined rapidly in the first seven days of storage and remained stable for the remaining storage period, unlike for acetic acid concentration that increased with storage period. On the other hand, counts of lactic acid bacteria and yeasts decreased during the storage. Gas production and dry matter loss increased with the length of storage. The storage period increased all variables stability aerobic. Most of significant improvements in stability aerobic were observed during the first 60 days of storage. Ruminal degradability of starch and, consequently, dry matter increased along the storage. In the experiment II, the aim was to evaluate the influence of strategy of silage unload on the performance of dairy cows. Corn silage from a bunker silo was separated at unloading as silage from the upper half of the silo (top) or from the lower half of the silo (bottom) and used to compose total mixed rations fed to 24 lactating cows allocated in 12 randomized blocks, arranged in a cross-over design with 21 periods. Cows were housed in a tie-stall barn. All diets contained 60% of corn silage and were iso-nitrogen (16.5% CP) and iso-starch (17.0% of starch). Dry matter intake, milk yield and composition were determined from day 15 to 21 in each period. Although silage from bottom led to higher total tract DM digestibility and lower milk urea nitrogen concentration (8.95 vs. 11.35 mg/dL), most of evaluated variables were not affected by treatments. Under optimal silo management, the strategy used to unload corn silage does not affect the performance of dairy cows.