Skeletal muscle consists predominantly of muscle fibers surrounded by a connective tissue layer. This tissue has a great plasticity, and the knowledge of the morphological characteristics, myogenesis, and growth dynamics is important to the understanding of its physiology and to the farm animal selection for meat production. Most skeletal muscles are derived from mesodermal precursor cells originated from the somites. During embryonic development, specification of mesodermal precursor cells to the myogenic lineage is regulated by positive and negative signals from […]

Microarray technology allows monitoring thousands of genes simultaneously in a specific tissue of an organism, in different developmental stages or environmental conditions. Microarrays are very common in functional genomics experiments with both animals and plant species, and they have been increasingly used also in different areas of livestock research, such as growth and metabolism, reproduction, immune response to diseases and parasites, response to non-infectious stress factors (such as dietary restriction, exposure to toxic elements and other unfavorable environmental conditions) as […]

Finite mixture models are helpful for uncovering heterogeneity due to hidden structure; for example, unknown major genes. The first part of this article gives examples and reviews quantitative genetics issues of continuous characters having a finite mixture of Gaussian components. The partition of variance in a mixture, the covariance between relatives under the supposition of an additive genetic model and the offspring-parent regression are derived. Formulae for assessing the effect of mass selection operating on a mixture are given. Expressions […]

Methodological advances are usually a direct consequence of conceptual and technical advances. In the case of animal intake on pasture, recent conceptual advances regarding the process of searching and apprehension of the forage by the ruminant provide insight regarding the importance of the basic unit of intake, the bite, and the importance of processes limiting intake that occur before the forage reaches the rumen. Applying a reductionist approach to the grazing process, along with its spatial-temporal hierarchy, brought a new […]

Grasslands are being replaced by urbanization and more profitable agricultural activities around the world. Producers may be faced with land constraints and need to consider intensification of the remaining grasslands as a means of maintaining overall production on a decreasing land resource. However, intensification of the grazing system is usually associated with greater nutrient inputs, including those from commercial fertilizers and supplement fed to animals. Excessive loading of nutrients in intensive grazing systems via fertilizer and animal wastes can cause […]

A mechanistic simulation model of fish larval growth should contribute to a better understanding of growth and metabolism of fish larvae. It should also assist in studying the nutritional requirements and developing feeding strategies. A model was developed that simulates growth and biochemical composition in time. The model is driven by feed intake, with absorbed nutrients being used for energy production and biosynthesis, based on the stoicheometry of intermediary metabolism. Model simulations suggest that imbalanced dietary amino acid (AA) profiles […]

The suitable evaluation of nutritional value of forages depends on the adoption of appropriate methodologies. Forage quality is highly dependent of fermentation products, in case of silage, and the losses of soluble compounds and microorganisms activity in the case of hay. The theme “Methodological advances in evaluation of preserved forage quality” at the 44th Annual Meeting of Brazilian Society of Animal Science has as main goals to highlight the more useful and particular methodological procedures for conserved forages and additional […]

“The most important collateral effect of knowledge is ignorance. Just imagine someone else living in the knowledge island circulated by a sea of ignorance. When the surface of the island grows through the progress of science, also grows its border, its perimeter length, the frontier with the unknown”. (David Gross, 2004 Nobel laureate) The use of stable isotopes of bioelements (CHONS) are present in atmosphere, hydrosphere, lithosphere and biosphere, emerging as high potential tools for researches within different areas of […]

The objective of this study was to evaluate the effect of replacing (0 and 100%, DM basis) soybean meal with urea, in diets with two levels of concentrate (0.75 and 1.25% of BW), on intake, nutrient digestibility, and ruminal metabolism in cattle. It was also of particular interest to investigate the variation in the daily excretion of internal (iADF) and external (Cr2O3) markers. Four Holstein steers averaging 445 kg of BW and fitted with ruminal and abomasal cannulas were used […]

The objective of this trial was to evaluate the effect of different dietary fat sources on intake, digestibility, and plasma urea N in feedlot water buffalo steers. Thirteen castrated Murrah steers averaging 297±9 kg of body weigh were assigned to one of the following three treatments: no added fat (control), soybean oil or whole soybean in a completely randomized design. The experiment lasted 84 days with three experimental periods of 28 days each. Samples of feeds, orts and feces were […]