Soil organic carbon and nitrogen can be divided into labile and recalcitrant pools according to the time it takes to be cycled. The way in which carbon and nitrogen pools are cycled and distributed between labile and recalcitrant pools can directly relate to soil quality. This paper tested the hypothesis that labile and recalcitrant pools of carbon and nitrogen vary between agricultural soils with different species and fertilization management systems (nitrogen, phosphorus, and potassium need) under tropical conditions. This study aimed to examine the impact of land-uses on stocks and losses of carbon and nitrogen under tropical conditions. We explored labile (soil microbial biomass and labile carbon) and recalcitrant carbon pools (humin, humic acid, and fulvic acid) in forested and agricultural soils, defined as latosol (forest, fertilized pasture, and unfertilized pasture) and cambisol (forest, coast pasture, sugarcane, and silage corn). Forested soil was used as an appropriate use to soil conservation in tropical that presents levels adequate of carbon and nitrogen stocks and biological condition in soil. Results showed that pools of labile and recalcitrant carbon are different on soil layers and the use of soil. Forest use in cambisol and latosol promoted higher labile and recalcitrant pools of carbon and nitrogen due to the greater environmental stability without human intervention. On the other hand, human intervention occurred in fertilized pasture and coast pasture; however, both uses presented similar recalcitrant carbon and nitrogen pools when compared to forested soil on the soil surface due to fertilizer uses and the high volume of the grass root system. Overall, our findings reveal that under tropical conditions, agriculture and forested soil can present similar recalcitrant pools of carbon and nitrogen if agricultural soils are associated with the appropriate fertilizer management. Pasture with adequate fertilization management systems can be used as an alternative to recover degraded areas with low levels of recalcitrant carbon and nitrogen pools.

This study represents the second phase of a longitudinal experiment evaluating the long-term cumulative effects of feeding strategies initiated at birth on the body development, metabolic profile, and feed efficiency of Gir dairy heifers during the rearing period. Thirty-four Gir dairy heifers participated in this study, which took place over a period of 133 days (21 days of adaptation and 112 days of data collection). A randomized block design was used with two treatments applied at birth: a conventional feeding plan (CF), offering 4% of body weight (BW) as dry matter (DM), and an optimized feeding plan (OF), offering 5% of BW as DM. Growth, feed efficiency, metabolic profile, and vulvar and teat morphometry were evaluated. Data were analyzed using linear and generalized mixed models. Average DM intake was 2.51% and 2.46% of BW for OF and CF, respectively. Heifers on OF showed a greater average chest circumference than those on CF. No differences were observed between treatments for residual feed intake, feed efficiency and feed conversion, teat and vulvar morphometry, or blood parameters. Our findings indicate that the growth differences established under the feeding plan initiated at birth were maintained throughout the rearing period, with no effects on feed efficiency, metabolic profile, or mammary gland development.

O milho (Zea mays L) tem importância mundial como comodity por ser a principal fonte de energia utilizada na alimentação animal. A anatomia do milho e dividida em endosperma (83%), pericarpo (5%), gérmen (11%) e ponta (2%). Os grânulos de amido e a matriz de proteína do endosperma classifica o milho em dois tipos: farináceo e vítreo. A relação endosperma duro (Flint) e farináceo (Dent) define a vitreosidade de um grão de milho. Desta forma, quanto maior a vitreosidade, maior a quantidade de endosperma duro presente no grão. Hoje no mercado existem cultivares de milho específicos para a produção de grão, milho-verde, milho-doce, milho-branco (canjica), silagem, pipoca, entre outros. As cultivares variedades são altamente heterozigóticos, com maior estabilidade produtiva, tendo maior variabilidade genética, menor uniformidade no produto e baixa produtividade, causada pela baixa heterose, possuem grande rusticidade e adaptabilidade sendo indicado pra sistemas de baixa tecnologia. Os híbridos comerciais são resultantes do cruzamento entre indivíduos geneticamente distintos e homozigotos, para máxima resposta da heterose. Os híbridos simples são potencialmente produtivos e indicados para sistemas que empregam alta tecnologia. O milho híbrido transgênico é obtido pela Engenharia Genética a partir da modificação do DNA pela introdução de genes de outras espécies por meio das técnicas do DNA recombinante. A transgenia objetiva três alvos principais, que podem ser classificados como: tolerância ao herbicida; inserção de genes de resistência a insetos e doenças; e qualidade de produtos. O milho-branco é uma cultivar especial que se caracteriza por ter grão dentado e farináceo, é muito utilizado pra produção de canjica, amido (maizena), farinha e etc. O milho-pipoca é uma cultivar especial de baixa produtividade com grãos de formato arredondado, endosperma totalmente vítreo, e película fina o que permite a espação quando o grão e aquecido. O milho-verde é uma alternativa à horticultura familiar por agregar mais renda, refere-se ao milho colhido ainda em estádio leitoso, apresentando de 70 a 80% de umidade. O milho-doce e super doce também se incluem como milho-verde, difere do convencional por ser destinado a indústria de enlatados e pela presença de alelos mutantes que bloqueiam a conversão de açúcares em amido, no endosperma, conferindo o caráter doce, tornando o milho doce enrugado e translúcido quando seco. O homem selecionou e desenvolveu várias cultivares de milho com características distintas e especiais para cada sistema de cultivo e finalidade de uso. Este estudo tem como objetivo O presente trabalho tem como objetivo abordar através de uma revisão de literatura as características anatômicas e nutricionais do grão de milho e o abordar os diferentes cultivares utilizados na agricultura brasileira.

The study aimed to assess the performance of Gyr dairy heifers in four pasture systems: renovated pasture (RP), non-renovated pasture (NRP), crop-livestock integration (CLI) and crop-livestock-forest integration (CLFI). For our study, we used a Marandu Palissadegrass pasture with a slight to moderate stage of degradation. The experimental area had 7.5 hectares which were divided into 3 blocks with four grazing systems: RP, NRP, CLI and CLFI. Thirty-four Gyr dairy heifers with an initial body weight (BW) of 206.9 kg were used. There was no difference in total forage production between the grazing systems. The RP system had a higher % of leaves, while the NRP showed a lower % of leaves and a higher % of dead material. The CLFI showed the highest % of crude protein (CP) in the forage, and lowest levels in the NRP. There was no difference between the grazing systems in the % of neutral detergent fiber (NDF) and acid detergent fiber (ADF). When the BW factor was analyzed in isolation, it was observed that the NRP had a higher BW and there was a linear increase in BW as the grazing cycles progressed. There was an interaction between grazing systems and evaluation periods for the variables related to grazing behavior, with emphasis on the heifers in the NRP system, which ruminated for longer and grazed for less time during the evaluation period. The RP, CLI, and CLFI systems, when established, promoted a pasture of better morphological and nutritional quality for rearing Gyr dairy heifers.

Maize (Zea mays L) is of global importance as a commodity because it is the main source of energy used in animal feed. The anatomy of corn is divided into endosperm (83%), pericarp (5%), germ (11%) and tip (2%). The starch granules and the protein matrix of the endosperm classifies corn into two types: farinaceous and vitreous. The relationship between hard endosperm (Flint) and floury (Dent) defines the vitreousness of a corn grain. Thus, the greater the vitreousness, the greater the amount of hard endosperm present in the grain. Today on the market there are specific corn cultivars for the production of grain, green corn, sweet corn, white corn (hominy), silage, popcorn, among others. The cultivars varieties are highly heterozygous, with greater productive stability, having greater genetic variability, less uniformity in the product and low productivity, caused by low heterosis, have great rusticity and adaptability, being indicated for low technology systems. Commercial hybrids are the result of the crossing between genetically distinct and homozygous individuals, for maximum heterosis response. Simple hybrids are potentially productive and suitable for systems that employ high technology. Transgenic hybrid corn is obtained by Genetic Engineering from the modification of DNA by introducing genes from other species through recombinant DNA techniques. Transgenics aims at three main targets, which can be classified as: herbicide tolerance; insertion of insect and disease resistance genes; and quality of products. White corn is a special cultivar that is characterized by having toothed and floury grain, it is widely used for the production of hominy, starch (cornstarch), flour and etc. Popcorn is a special cultivar of low productivity with rounded grains, fully vitreous endosperm, and thin film which allows spacing when the grain is heated. Green corn is an alternative to family horticulture because it adds more income, it refers to corn harvested while still in the milky stage, with 70 to 80% moisture. Sweet corn and super sweet corn are also included as green corn, differs from conventional corn in that it is intended for the canning industry and by the presence of mutant alleles that block the conversion of sugars into starch in the endosperm, giving it a sweet character, making sweet corn wrinkled and translucent when dry. Man has selected and developed several maize cultivars with distinct and special characteristics for each cropping system and purpose of use. The present study aims to address through a literature review the anatomical and nutritional characteristics of the maize grain and to address the different cultivars used in Brazilian agriculture.

This study assessed the productive and structural traits of the forage canopy and the performance of heifers grazing Marandu grass pastures overseeded with winter forages during the dry–wet transition in a tropical region. A completely randomized split-plot design with three replicates was used to compare three systems: Marandu grass overseeded with Oats and Ryegrass; Marandu grass overseeded with Oats and Clovers; and Marandu grass in monoculture. Holstein × Gyr heifers, averaging nine months of age with an initial body weight of 225.42 ± 50.27 kg, were managed under irrigated rotational grazing, with two days of occupation and 28 days of rest. Measurements were taken over three grazing cycles. Total forage mass and Marandu grass mass increased in the final cycle, with no differences among systems. The proportion and mass of winter forages did not differ between treatments, although overseeded pastures maintained about one-third of their composition as winter species. Animal performance was similar across systems, with greater body weight observed at the end of the experimental period. In conclusion, overseeding winter forages in irrigated Marandu grass pastures does not increase forage production or animal performance but does promote botanical diversification, with Oats showing better adaptation under these conditions.