Abstract The objective of the present study was to evaluate the productive performance, the ingestive behavior, the apparent digestibility of the diet, and the carcass characteristics of beef steers finished in confinement under the effect of ammonium dipropionate in the diet, and the fractionation or not in the supply of the diet. The experimental design was completely randomized, in a 2 x 2 factorial scheme, totaling four treatments, as follows: Diet without ammonium dipropionate provided twice a day; Diet without ammonium dipropionate given once daily; Diet with ammonium dipropionate provided twice daily; Ammonium dipropionate diet provided once daily. Thirty-two ½ Angus ½ Nellore bulls were used, with an average age of 11 months. The use of ammonium dipropionate in the overall average increased average daily gain, dry matter intake, and carcass gain. The diet provided twice a day provided, on average, greater weight gain, greater carcass gain, and better feed conversion. When evaluating the association between treatments, the use of dipropionate plus the diet supplied twice a day showed greater daily carcass gain during the experimental period and higher hot carcass weight (1.251 kg, 111.4 kg, and 308.6 kg respectively), as well as ensuring better apparent digestibility of dry matter (74.57%). With the data obtained in the present study, it is possible to state that it is advisable to use ammonium dipropionate while maintaining the fractionation of the diet for beef steers in the finishing phase.

Resumo O objetivo do presente estudo foi avaliar o desempenho produtivo, o comportamento ingestivo, a digestibilidade aparente da dieta e as características de carcaça de novilhos de corte terminados em confinamento sob efeito do dipropionato de amônio na dieta, e do fracionamento ou não no fornecimento da dieta. O delineamento experimental foi inteiramente casualizado, em um esquema fatorial 2 x 2, totalizando quatro tratamentos, sendo: Dieta sem dipropionato de amônio fornecida duas vezes ao dia; Dieta sem dipropionato de amônio fornecida uma vez ao dia; Dieta com dipropionato de amônio fornecida duas vezes ao dia; Dieta com dipropionato de amônio fornecida uma vez ao dia. Utilizou-se 32 novilhos ½ sangue Angus ½ sangue Nelore, com idade média de 11 meses. O uso do dipropionato de amônio na média geral aumentou o ganho médio diário, a ingestão de matéria seca, e o ganho de carcaça. A dieta fornecida duas vezes ao dia proporcionou na média geral, maior ganho de peso, maior ganho de carcaça e melhor conversão alimentar. Ao avaliar a associação entre os tratamentos, o uso de dipropionato mais a dieta fornecida duas vezes ao dia mostrou maior ganho de carcaça diário, durante o período experimental e maior peso de carcaça quente (1,251 kg, 111,4 kg e 308,6 kg respectivamente), assim como garantiu melhor digestibilidade aparente da matéria seca (74,57%). Com os dados obtidos no presente estudo é possível afirmar que é recomendável utilizar o dipropionato de amônio mantendo o fracionamento da dieta para novilhos de corte em fase de terminação.

ABSTRACT The objective of this study was to evaluate the effect of harvesting corn at different maturity stages for silage production combined with four storage periods, considering nutrient loss and the chemical composition of silage of the whole plant and also of grainless plants. The experiment was performed in a completely randomized design with a factorial arrangement of six maturity stages of corn [reproductive (R); R1 to R6] and four periods of silage storage (30, 60, 90, and 120 days). At stages R1 and R2, losses by effluents occurred more intensely when compared with the more advanced stages, whereas losses by gases showed the opposite behavior, with stage R6 responsible for the greatest losses. Stage R4 showed a stable dry matter (DM) content during the storage period, 42.08%, and had the lowest levels of neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) for the whole plant silage. The ADL in the silage of grainless plant of stage R4 was not the lowest, but it was close to the first reproductive stages, being an important point, since the first reproductive stages can present a vegetative fraction of better quality. The highest DM volumes produced by area occurred in the most advanced stages; however, R5 obtained a greater reduction in volume over the days of storage (20.66 kg day −1 ). The production cost was lower at the advanced stages (R4, R5, and R6) when compared with the first reproductive stages (R1, R2, and R3), and in general, during the storage period the costs did not have great variations. Based on the chemical composition of the silages, DM losses during the storage period, the stability in the costs of DM ton over the days of storage, the R4 stage was the most suitable for silage production.

Resumo Objetivou-se neste trabalho avaliar alimentos energéticos quanto a composição química, degradabilidade ruminal in situ da matéria seca (DMS), cinética ruminal e taxa de desaparecimento ruminal da matéria seca. Foram avaliados sete alimentos (tratamentos): grão de milho moído, grão de aveia moído, grão de cevada moído, farelo de trigo, casca de soja, radícula de malte e gérmen de milho, num delineamento inteiramente casualizado com quatro repetições cada. Para a incubação dos materiais foram utilizados dois bovinos com cânula ruminal, e cada tratamento foi submetido a sete períodos de exposição ao rúmen (0, 3, 6, 9, 12, 18 e 24 horas). Dentre os alimentos avaliados, a casca de soja teve o maior teor de fibra em detergente neutro (68,91%) e apresentou a menor DMS em 24 h (64,91%). O grão de cevada moído e o grão de milho moído tiveram os menores níveis de fração solúvel (FS) (26,34% e 28,7%, respectivamente), porém o grão de cevada moído apresentou a maior DMS em 24 h (90,48%), que por conciliar estes parâmetros teve a maior taxa de desaparecimento ruminal (2,50%.h-1), enquanto o grão de aveia moído teve a maior FS (47,75%) e a menor taxa de desaparecimento ruminal (1,09%.h-1).

Abstract This study aimed to evaluate energetic feedstuffs regarding chemical composition, in situ ruminal degradability of dry matter (DMD), ruminal kinetics and ruminal disappearance rate of dry matter. Seven feedstuffs (treatments) were evaluated: ground corn, ground oat, ground barley, wheat bran, soybean hull, malt root and corn germ, in a completely randomized design of four repetitions each. Two bovines ruminally cannulated were used for incubation, wherein each treatment was subjected to seven periods of exposure to the rumen (0, 3, 6, 9, 12, 18 and 24 hours). Among the evaluated feedstuffs, soybean hull had the highest neutral detergent fiber (NDF) content (68.91%) and the lowest DMD at 24 h (64.91%). Ground barley and ground corn contained the lowest content of soluble fraction (SF) (26.34 and 28.7%, respectively), among which ground barley had the highest DMD at 24 h (90.48%) and therefore showed the highest rumen disappearance rate (2.50%.h-1) by combining both parameters, while the ground oat presented the highest SF (47.75%) and the lowest rumen disappearance rate (1.09%.h-1).

Resumo O objetivo deste trabalho foi avaliar a eficiência de diferentes filmes plásticos dupla face sobre as características quimiofermentativas, digestibilidade da matéria seca, estabilidade aeróbica, perdas físicas e de matéria seca de silagens de milho armazenadas em silos trincheira. O delineamento experimental utilizado foi inteiramente casualizado, compostos por três tratamentos: DF110µm - polietileno dupla face com espessura de 110 µm; DF200µm - polietileno dupla face com espessura de 200 µm; e DFBO - película impermeável ao oxigênio composta de polietileno dupla face com espessura de 80 µm sobreposta a uma película de poliamida translúcida a vácuo com espessura de 20 µm. O uso do filme DF200µm aumentou em 4,58% a digestibilidade ruminal da matéria seca e reduziu em 3,1 °C a temperatura da silagem, assim como as perdas físicas da silagem de milho foram reduzidas em 118,9 g kg-1 da MS pela utilização do DFBO e 95 g kg-1 da MS com o DF200µm, o DFBO apresentou a maior estabilidade aeróbica (127 horas) da silagem de milho. O uso de filme DF200µm e DFBO é recomendado para conservação de silagem de milho em silos do tipo trincheira.

Abstract The objective of this study was to evaluate the efficiency of different double-sided plastic films on chemical and fermentation characteristics, dry matter digestibility, aerobic stability, physical and dry matter losses in corn silages stored in bunker silos. This was a completely randomized experimental design consisting of three treatments: DF110µm - double-sided polyethylene with 110 µm thickness; DF200µm - double-sided polyethylene with 200 µm thickness; and DFBO - oxygen-impermeable film consisted of double-sided polyethylene with 80 µm thickness overlaid with a translucent vacuum polyamide film with 20 µm thickness. The use of DF200µm film increased the ruminal dry matter digestibility by 4.58% and reduced the silage temperature by 3.1 °C, as well as the physical losses of the corn silage were reduced by 118.9 g kg-1 DM using DFBO and 95 g kg-1 DM with DF200µm; DFBO resulted in the highest aerobic stability (127 hours) of corn silage. The use of DF200µm and DFBO is recommended for preserving corn silage in bunker silos.