A adubação nitrogenada possibilita aumentar a capacidade de suporte das pastagens, entretanto, o uso de elevadas doses pode causar efeitos negativos no crescimento de gramíneas forrageiras. A partir do pressuposto, objetivou-se avaliar a influência de doses crescentes de nitrogênio sob as características morfogênicas e estruturais, acúmulo de biomassa e eficiências de conversão e recuperação do nitrogênio em pastagem de Megathyrsus maximus cv. BRS Zuri. Foram testadas cinco doses de nitrogênio (0, 200, 400, 600 e 800 Kg de nitrogênio/ha) em delineamento experimental de blocos casualizados, com quatro repetições. Foi observado comportamento quadrático para as taxas de alongamento e aparecimento foliar, tempo de vida e o filocrono. Houve aumento no número de perfilhos e na produção de matéria seca quando as plantas foram submetidas à adubação, porém, tanto a eficiência de utilização quanto a recuperação aparente do nitrogênio reduziram linearmente com o aumento do nível de nitrogênio. O uso de fertilizante nitrogenado promoveu melhora nas características morfogênicas (P<0,05) exceto para taxa de alongamento de colmo e taxa de senescência foliar que se mantiveram estáveis. A Adubação com nitrogênio acelera as taxas de crescimento do Megathyrsus maximus cv. BRS Zuri. As respostas máximas nas variáveis morfogênicas, no número de folhas vivas e totais por perfilho são obtidas com doses próximas de 500 kg/ha, enquanto que doses variando de 600 a 647 kg/ha proporcionam maior tamanho de folha por perfilho, densidade populacional de perfilhos e produção de matéria seca. As eficiências de utilização e recuperação do nitrogênio reduzem com o aumento das doses de nitrogênio.

Two studies evaluated the productive characteristics of young Nellore heifers receiving different days on feed (DOF) to determine the biological slaughter endpoint. In Experiment 1 (Exp. 1), fifty-one Nellore heifers [324 ± 19.3 kg of body weight (BW); 16 ± 1 months] were split into three DOF lengths (45, 75, or 105 days), while in Experiment 2 (Exp. 2), thirty-six Nellore heifers (362 ± 25.5 kg of BW; 18 ± 1 months of age) were split into three DOF lengths (45, 90, or 135 days). In both studies, all animals were distributed in complete randomized blocks according to initial BW and stratified via carcass ultrasound. The diet was supplied ad libitum, allowing 3% of refusals. The point at which the animals achieved 25% of ether extract of shrunk body weight (EE_SBW) was defined as the biological endpoint. Thus, relationships were made between some characteristics obtained in both studies. Positive linear relationships were found between backfat thickness (BFT) vs. EE_SBW (p < 0.001, r = 0.84) and BFT vs. body weight (p < 0.001, r = 0.77). Our results suggest that the biological slaughter endpoint for young Nellore heifers is 6.97 mm of backfat thickness or 402 kg shrunk body weight, corresponding to around 75 DOF.

The objective of this study was to compare rehydrated corn grain silages using water or whey and inoculated (Lactobacillus plantarum and Propionibacterium acidipropionici) or not. We also verified whether rehydration with whey associated with the bacterial inoculant improves material conservation. The treatments were as follows: silages rehydrated with water without inoculant (SWa); silages rehydrated with water and inoculated (SWaI); silages rehydrated with whey without inoculant (SWe); silages rehydrated with whey and inoculated (SWeI). A completely randomized design was used, with three replications, treatments in a 2 × 2 factorial scheme (RE: rehydration with water or whey, and IN: inoculation or addition of water without chlorine), during the following storage periods (T): 0, 4, 8, 16, 32, and 64 days. There was an RE x IN x T interaction (P < 0.001) for dry matter (DM), with lower values over time for SWe and higher values in SWeI. An interaction between RE x IN (P < 0.001) and IN x T (P < 0.001) was observed for pH, with higher values for SWe at 64 days of storage and a reduction from the first days of ensiling for SWaI and SWeI. The microbiological variables showed an RE x IN x T interaction (P < 0.001), with the highest counts of lactic acid bacteria for SWaI and SWeI up to 8 days of storage and subsequent higher counts in SWa and SWe. Higher counts were obtained in SWe. For the variables of fermentative losses, there was an RE x IN x T interaction (P < 0.001), with SWeI showing lower losses. The inoculation associated with whey for rehydration of corn grain improved the fermentation profile of the silage, with lower pH values and reduced losses.

The objective of this study was to evaluate four different feeding strategies using an immunomodulatory feed additive for newly weaned Nellore cattle, before and after road transport, on their physiological parameters and performances during the growing phase of pastures. In total, eighty-four young Nellore bulls (initial BW = 174 ± 11 kg; 7 ± 1 months of age) were blocked by their initial body weights 42 days before road transport (d −42) and randomly assigned to one of the four supplementation strategies. The treatments were: (1) Control (CON): no immunomodulatory feed additive (NUTRA) supplementation; (2) NUTRA pre: the inclusion of NUTRA only in the pre-transport period (d −42 to d 0); (3) NUTRA post: the inclusion of NUTRA for 42 days, only in the post-transport period (d 0 to d 42); and (4) NUTRA growth: the inclusion of NUTRA during the whole experimental period (d −42 to d 210). On d 0, the calves were transported on dirty roads in a commercial livestock trailer for 200 km (8 h). There was no effect of the treatments on the animal performance or the physiological parameters in their plasma. However, there were effects on the day of the blood sampling for all the parameters. The highest concentration of cortisol was observed on d 3 post-transport (129 ng/mL) and this decreased over time (22.4 ng/mL; d 210). On the other hand, their glucose peaked at unloading, with lower concentrations on d 7 and d 14. Their total protein concentrations increased from d 0 to d 7. The immunomodulatory feed additive supplementation at 10 g/100 kg BW/day did not modulate the physiological responses in their plasma and did not influence the performance of the Nellore bulls during the growing phase of their pastures.

A introdução de forragens conservadas na dieta animal é uma estratégia viável e de grande relevância, não somente nos períodos de escassez de forragem ofertada via pastejo, mas também, nos sistemas de produção onde o rebanho é confinado, e a base alimentar depende da utilização de alimentos conservados, que participam em níveis expressivos na composição da dieta. Entretanto, uma série de circunstâncias tais como condições climáticas, falta de maquinários e insucesso no planejamento forrageiro, podem tornar-se fator complicador para que a produção de silagem ocorra de maneira eficiente, assegurando a quantidade e qualidade demandada na propriedade. É justamente neste contexto, que a prática de realocação de silagem ou reensilagem surge como opção crescente no Brasil, visando atender as demandas mencionadas anteriormente, assim como fortalecer o mercado focado na comercialização de silagem entre fazendas. Com isso, o objetivo deste trabalho foi realizar uma revisão de literatura para abordar os aspectos inerentes à realocação de silagem dentro da propriedade rural. A metodologia empregada possui natureza qualitativa e cunho descritivo. Os resultados das pesquisas apontam possível impacto na qualidade de silagens realocadas, porém alguns deles podem existir em função da exposição e possível deterioração aeróbia da silagem, influenciando o consumo e desempenho animal. Os estudos têm demonstrado que esta é uma prática passível de realização, no entanto a eficiência ao longo de todo processo estará intimamente ligada à qualidade do produto final que será ofertado aos animais.

Procedures such as transport and marketing can subject animals to water and feed deprivation and impair animal health and performance. Maintaining the mineral status of animals under these conditions can bring benefits to health and performance. The use of hydroxychloride mineral sources can improve mineral status, nutrient digestibility and performance. Two studies were conducted to investigate how the supplementation of 02 trace mineral sources of Cu and Zn and 48-hour water/feed deprivation would affect the performance and metabolism of grass-fed beef cattle. In the first study, 20 castrated and rumen-canulated Nellore steers (BW = 350 ± 132 kg; 20 m) were distributed in individual pens, in a 2 × 2 factorial arrangement: supplemental Cu and Zn sources from inorganic vs hydroxychloride (HTM) and 48-hours deprivation (WFD) vs unrestricted (WFU) access to water and feed. The 57d of study was divided into two periods: (1) Adaptation from -21d to -1d and (2) evaluation from 0d to 36d. Interaction between deprivation × period was detected (P < 0.05) for digestibility of DM (DMD), organic matter (OMD), neutral detergent fiber (NDFD), and acid detergent fiber (ADFD). Deprivation increased DMD, OMD, NDFD, and ADFD immediately after the deprivation period (3-5d), but impaired digestibility at longer periods such as 11-13d and 32-34d. DM (DMI) and nutrient intake (P = 0.075), as well as NDFD were higher in HTM. Several ruminal parameters were affected by deprivation: short-chain fatty acids concentration decreased, while rumen pH increased (deprivation × time; P < 0.05); decreased propionate, butyrate and increased isobutyrate, isovalerate, and valerate in WFD (deprivation × time; P < 0.05), respectively. In the second study, eighty-four intact Nellore males (BW = 260 ± 35 kg) were blocked by BW and randomly assigned to Urochloa brizantha cv. Marandu paddocks for 131d in a 2 × 2 factorial arrangement. Liver Cu was higher in WFU/HTM animals (mineral × deprivation; P < 0.05). Interaction between deprivation × period (P < 0.05) was detected for BW and average daily gain (ADG). On 2d and 12d after deprivation, WFD increased ADG and recovered the BW lost. In conclusion, water and feed deprivation imposed in these trials were able to impact several nutrient digestibility and ruminal fermentation parameters in short- and long-term. Performance was not affected by the studied factors. Furthermore, supplementation with sources of Cu and Zn hydroxychloride increased Cu in the liver and tended to increase DMI and NDFD.