Semina. Ciencias agrarias

To meet the growing demand for beef, various technologies have been adopted to improve cattle performance and feed efficiency, such as intensive systems and dietary additives. This study evaluated the productive performance of feedlot-finished steers with yeast culture (Saccharomyces cerevisiae), either combined with or without sodium monensin in their diet. The 140-day experiment used 240 ½ Angus x ½ Nellore steers from the same herd. The steers were 13.8 ± 1.0 months of age and had 421 ± 5 kg initial body weight. The completely randomized experimental design consisted of two treatments and six repetitions, with each repetition represented by a pen containing 20 animals. The treatments were (1) diet with sodium monensin (250 mg animal-1 day-1), and (2) diet with yeast culture plus sodium monensin (7 g animal-1 day-1 + 250 mg animal-1 day-1). The diets consisted of a mixture of 40% corn silage and 60% concentrate, provided ad libitum. Using yeast culture combined with sodium monensin promoted higher average weight gain (1.324 vs. 1.083 kg day-1) and consequently higher body weight at slaughter (565.3 vs. 537.6 kg) and hot carcass weight (312.6 vs. 296.8 kg) compared to the diet with only sodium monensin. Furthermore, adding yeast culture to the diet promoted greater carcass gain (103.7 vs. 85.3 kg) and higher average daily carcass gain (0.947 vs. 0.819 kg day-1) than the treatment with sodium monensin alone. The addition of yeast culture combined with sodium monensin to the diet increased the average daily gain by 22.2% and the daily carcass gain by 15.6%, so it is recommended for finishing steers in a feedlot.

The combination of soybean seeds with low moisture content and treatment with phytosanitary products in seed germination assessment has led to inconsistent results in the rolled paper (RP) germination test. The premoistening technique, which involves slowly hydrating the seeds before the germination test, can be used to mitigate imbibitional injury in seeds with low moisture content. The rolled paper + vermiculite (RP+V) substrate, on the other hand, reduces the phytotoxicity of phytosanitary products. Therefore, this study aimed to assess whether premoistening is necessary when using the RP+V substrate. For this assessment, soybean seeds from a single lot were dried to different moisture contents and were then treated or not treated with phytosanitary products. The experiment was carried out in a 3 × 2 × 2 factorial arrangement, consisting of three seed moisture contents (12%, 10%, and 8%), two types of premoistening activity (with and without), and two substrates (RP and RP+V). Premoistening improved germination rates, especially for seeds with 8% moisture content. Without premoistening, RP+V enhanced seed-quality expression, possibly reducing imbibitional damage. In addition, RP+V resulted in a higher percentage of strong normal seedlings, signaling better initial development. It can be concluded that RP+V does not eliminate the need for premoistening, and both are effective practices in assessing the quality of low moisture content soybean seeds, even when they have been treated with phytosanitary products. This combination of techniques optimizes the germination test, ensuring more reliable results for assessing germination potential.

Melons and cucumbers are sensitive to the allelopathic effects of certain weeds, which can affect their germination, development, and productivity. Among these weeds, horseweed (Conyza sp.) stands out for its ability to interfere with several economically important crops, and is difficult to control because of its tolerance to glyphosate. Considering the importance of melon and cucumber production, and their competitive interactions with weeds, these crops require special attention from germination to harvest, mainly because of their susceptibility to competition. This study aimed to identify the effects of an aqueous extract of horseweed leaves (Conyza bonariensis) on seed germination and seedling development of melon and cucumber under laboratory and greenhouse conditions. The percentage of abnormal plants, seed germination rate, and biometric traits such as root and shoot lengths, seedling dry mass, and hypocotyl length were evaluated under different extract concentrations (1:5, 1:10, 1:15, and 1:20 v/v). The results indicated that horseweed extract increased both the germination percentage and growth of the root and shoot systems of melon seedlings in both environments. The findings demonstrated that both the environment (laboratory and greenhouse) and species influenced the response to the aqueous extract. The horseweed extract exhibited a variable effect: in some cases, it stimulated germination while reducing seedling growth, whereas in others, it reduced germination but stimulated growth. This variation is mainly attributed to environmental effects, genotypic differences, and their interactions. Furthermore, extract concentration played a significant role, as lower concentrations stimulated while higher concentrations inhibited the development of melon and cucumber seedlings.

Nile tilapia (Oreochromis niloticus) is the most commercially available species of freshwater fish in Brazil. As producers intensify their operations to meet market demand, there is a growing need for strategies to accelerate growth and optimize feed use. Functional feed additives such as β-glucan, mannan oligosaccharides (MOS), and dietary nucleotides have been researched individually, with the goal of enhancing growth performance; however, studies on their combined use in tilapia remain limited. The aim of this study was to compile and analyze growth performance data from three trials evaluating these additives, applied individually and in combination, in Nile tilapia under different initial weights, feeding durations, and rearing conditions. A total of 492 fish were used in the three experiments. In the first 46-day trial with fingerlings (~8 g), six treatments were tested: 1) control diet, 2) β-glucan/MOS (2 g/kg), 3) Nucleotides 15% (2.1 g/kg), 4) β-glucan/MOS combined with Nucleotides 15% (1.05 g/kg each), 5) Free nucleotides (2.1 g/kg), and 6) Free nucleotides+β-glucan/MOS (1.05 g/kg each). The results showed that the diet containing nucleotides extracted from Saccharomyces cerevisiae cell walls (nucleotides 15% ) improved the final weight, length, and specific growth rate compared to the corresponding values in the control group, emphasizing the benefits of polynucleotide structures in nutrient absorption. In the second trial (30 days) fish weighing ~25 g were used to specifically evaluate the combined additive (β-glucan/MOS + nucleotides 15% at 1.05 g/kg each) in comparison to the control group. The fish receiving this diet consumed significantly less feed daily while maintaining a similar weight gain, possibly indicating improved feed efficiency and potential metabolic synergy of the additives. The third trial, which replicated the same six treatments as the first experiment but over only 30 days, showed no significant differences among groups in terms of either growth or feed parameters. Notably, none of the additives adversely affected performance in any trial, confirming their safety. These findings suggest that combining β-glucan, MOS, and nucleotides from two different sources, particularly yeast-derived nucleotides, can support enhanced growth over longer feeding periods and may (when combined with β-glucan/MOS) reduce feed intake in larger fish without compromising gains. In future studies, the feeding period should be extended beyond 46 days, and responses to health or environmental stress should be analyzed to better understand the additional benefits of the proposed diet. In summary, this study demonstrates the potential of integrated nutritional strategies to improve the efficiency and sustainability of Nile tilapia production.

This study aimed to evaluate the productive and bromatological characteristics of white and black forage oats grown either in monocropping or intercropping systems, and harvested according to the following treatment designations: TamPic: 90% GMX Tambo white oats + 10% GMX Picasso black oats; InvPicGau: 90% GMX Invernia white oats + 5% GMX Picasso black oats + 5% UPF Gaudéria white oats; TamGau: 30% GMX Tambo white oats + 70% UPF Gaudéria white oats; and Pic: 100% GMX Picasso black oats. All materials were subjected to three successive cuts, at the vegetative, full vegetative, and pre-flowering and/or dough grain stages. With cuts made at the vegetative and full vegetative stages, the TamPic intercropping had the lowest whole plant dry matter content and the lowest dry biomass production (11.71% and 979 kg ha-1). With cuts made at the pre-flowering and dough stages, the black oat cv. Picasso monocrop had lower proportions of leaves (43.5% and 15.4% respectively) and higher proportions of stems (53.1% and 60.3% respectively) compared to the other cropping systems. On average, the ruminal degradation of the forages after 168 hours of incubation was higher: 75.84% at the pre-flowering stage and 74.18% at the dough grain stage. In general, oats allow up to three cuts without significantly compromising quality and productivity, whether in monocropping or intercropping systems.