ABSTRACT The present study presents a comparative evaluation of the transit kinetics of straw briquette in response to the dietary addition of non-protein nitrogen sources in the form of a mineral supplement. Four rumen-cannulated, castrated Holstein-Gir crossbred cattle, weighing an average of 380±22.64 kg, were distributed into a 4 × 4 Latin square design (four supplements with non-protein nitrogen sources × four experimental periods). The following non-protein nitrogen sources were studied: conventional urea, slow-release urea, extruded urea, and monoammonium phosphate. During the experiment, the animals were housed in individual stalls with concrete floors where they received a basal diet consisting of straw briquette, potato starch, and the mineral supplement, the latter whose variation was only in the non-protein nitrogen source, which characterized the treatments. The different non-protein nitrogen sources did not affect the parameters of transit or degradation kinetics of straw fiber briquette. These results can be associated with the low nitrogen content limited by the types of supplements and the particle size of straw briquette, which is smaller due to processing. nonprotein non protein supplement rumencannulated, rumencannulated rumen cannulated, cannulated rumen-cannulated HolsteinGir Holstein Gir cattle 3802264 380 22 64 380±22.6 kg periods. periods . periods) studied urea slowrelease slow release phosphate experiment starch source treatments processing 380226 38 2 6 380±22. 38022 3 380±22 3802 380±2 380±

<p>Objetivou-se com este trabalho avaliar a cinética da taxa de passagem ruminal de partículas das silagens oriundas dos consórcios: milho e capim-braquiária; milho, capim-braquiária e calopogônio; milho, capim-braquiária e macrotiloma; e milho, capim-braquiária e estilosantes. Foram usados quatro bovinos mestiços holandês-zebu, fistulados no rúmen. As fezes foram coletadas nos tempos zero (imediatamente após a administração da fibra complexada com cromo), 1, 2, 4, 6, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 56, 64, 72, 80, 88, 96, 120, 132, 144 e 192 horas. As estimativas dos parâmetros dos perfis de taxa de passagem foram ajustadas de acordo com procedimentos de regressão robusta. O tempo médio de retenção de partículas no <italic>raft</italic> (<italic>TMR1</italic>); o tempo médio de retenção de partículas na fase líquida ruminal (<italic>TMR2</italic>) e o tempo médio de retenção ruminal total (<italic>TMRR</italic>) foram ajustados para a cinética de passagem e estimados com o procedimento NLIN do SAS. A partir dos resultados observados, pode-se sugerir que a taxa de transferência <italic>λ</italic> possui comportamento inverso à taxa de escape<italic>κ</italic>; os valores médios de <italic>τ</italic>, os tempos médios de retenção e os tempos médios de retenção de partículas na fase líquida ruminal (<italic>TMR2</italic>) não diferiram estatisticamente. As características cinéticas dos alimentos, após escaparem do <italic>raft</italic>e chegarem à fase líquida, foram equivalentes. Os <italic>TMRR</italic> das fibras das diferentes silagens não diferiram entre si (<italic>p<0,05</italic>). Observaram-se pequenas diferenças numéricas dos <italic>TMRR</italic> nos diferentes alimentos. As fibras das silagens em estudo tiveram taxas semelhantes de <italic>λ</italic>, k, TMR1,TMR2 e TMRR. Portanto, a cinética da taxa de passagem ruminal de partículas das silagens dos consórcios é semelhante. Assim, a tomada de decisão pelo tipo de consórcio a ser utilizado deve ser baseada em outros fatores, tais como viabilidade do manejo de culturas e custo da silagem.</p>

<p>The purpose of this study was to evaluate the kinetics of ruminal passage rate of particles from the subsequent associations: corn and signal grass; corn, signal grass and Calopogônio; corn, signal grass and Macrotiloma; and corn, signal grass and Estilosantes. It was used four crossbred holstein-zebu cattle with the rumen tubed in order to determine the the kinetics of ruminal passage rate of particles. The feces were collected at the times zero (immediately after addition of fibers complexed with chromium), 1, 2, 4, 6, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 56 , 64, 72, 80, 88, 96, 120, 132, 144 and 192 hours. The profile parameters of passage rate estimative were adjusted according to robust regression procedures. The average time of particles retention in the raft (ATPR1); the average time in the rumen liquid phase (ATRLP2) and the average time of total ruminal retention (ATTRR) were adjusted for the passage kinetics and estimated with the NLIN procedure of SAS. From the observed results, may be suggested that the transference rate <italic>λ</italic> has an inverse behavior to the escape rate <italic>κ</italic>, the <italic>τ</italic> average values, the average retention time and average particles retention time in the rumen liquid phase (ATRLP2) were not statistically different. The feed characteristics after the raft escape and reach to ATRLP2, were very similar; (ATTRR), related to treatments, were not statistically different (P<0,05). There were observed small TMRR numerical differences in different foods. The corn and signal grass; corn, signal grass and calopogônio; corn, signal grass and macrotiloma, corn, signal grass and estilosantes silage fibers had similar rates of<italic>λ</italic>, k, ATPR1, ATRLP2 and ATTRR. Therefore, the the kinetics of ruminal passage rate of particles is similar. Thus, the choice of the system should be based on other factors, such as viability of the management ease and silage cost.</p>

The objective of the present study was to evaluate the parameters related to the digestion of the fiber from silages of four corn hybrids (BX1280, SHS4070, 2B433, and DKB390) developed for silage production. Four rumen-cannulated castrated Holstein × Zebu crossbred cattle with approximate initial weight of 400 kg were distributed in a Latin square design. To determine the fiber passage rate and degradability, the techniques of chromium-mordant and in situ incubation of the neutral detergent fiber of the silages in nylon bags were used. The profiles of concentration of the marker in the feces were described by the generalized two-compartment model. Corn hybrid DKB390 is the most indicated for production of better-quality silages, because its fiber is more degradable in the rumen as compared with the other hybrids tested.

The objective of this study was to determine the kinetics of in situ degradability parameters of the dry matter (DM) and neutral detergent fiber (NDF) and the passage of materials originating from the ensilage of the waste from pineapple cultivation (aerial parts). The four treatments utilized were silage of pineapple waste compacted at 600, 700, 900 and 1000 kg/m³. After ensiling the material from the pineapple cultivation, the particle-transit and rumen-degradation kinetics were analyzed. For the analysis of particle transit, chromium was utilized as a marker to mark the fiber. Passage rates were determined by retrieving the markers in the feces of the animals. In the degradation assay, samples were incubated in nylon bags for 0, 6, 18, 48 and 96 hours. The behavior observed in the regression curves of the variables analyzed describes high correlation between them, i.e., the time during which the silage is retained in the rumen influences its digestibility and its degradation rate. Although the silage compacted at 900 kg/m³ shows a larger potentially digestible fraction, it is recommended that it be ensiled at a compaction density of approximately 750 kg/m³ due to the lower cost and shorter mean retention time in the rumen-reticulum and rumen fill, thereby increasing the ruminal degradation and passage dynamics.

The objective of this research was to identify the potential of maize hybrids for the production of silage. Hybrids 1671B, 2B433, 20A78, SHS4070, BX1280 and DKB390 were tested in a randomized block design with three replications. The hybrids yields were evaluated (average plant height, height of ear insertion, number of broken and lodged plants/ha, leaf:stem and ear:plant ratio and production of of DM, CP and TDN/ha). There was no difference between hybrids for the variables studied, except for the height of ear insertion. With respect to chemical characteristics, N-NH3/NT organic acids, and pH, there was also no difference between cultivars and hybrid silages are rated as of very good quality.