-The objective of this study was to evaluate the effect of addition of different levels of cottonseed (0, 14.35, 27.51 and 34.09 kg/100 kg) in the diet of Nellore steers on the meat characteristics. Thirty-six steers (average initial body weight of 333.50 and average age of 20 months) were kept in feedlot stalls for 94 days, each stall with three animals. The experiment was a completely randomized design with four treatments and nine replications. The values of protein, fixed mineral residue, shear force, lipid oxidation, meat color and fat color were similar among the treatments. The increase of the cottonseed levels in the diet reduced the amount of intramuscular fat and increased the moisture content in the meat linearly. Meat aroma and flavor were negatively influenced when cottonseed addition was greater than 27.51 and 34.09 kg/100 kg of the diet, respectively. Cottonseed diet did not modify the concentration of conjugated linoleic acid, saturated fatty acids or total unsaturated fatty acids, but linearly reduced the concentration of monounsaturated fatty acids in the meat.

An increased risk of acidosis in animals is associated with a high dry matter intake (DMI), which in turn results in the consumption of more fermentable organic matter (OM) in the rumen leading to a high production of volatile fatty acids (VFA). This is observed in lactating dairy cows and animals in a feedlot. Acute acidosis occurs when there is a severe drop in the pH of the rumen. A prolonged period when pH of in rumen remains low, it leads to sub-acute ruminal acidosis (SARA), which is a temporary imbalance between acid production and absorption. An associated change of an acute increase in the ruminal osmolarity and the accumulation of glucose and lactate in its stereoisomeric forms (D-lactate and L-lactate), is observed in the rumen fluid. However, in the sub-acute form, the accumulation of lactic acid occurs in the rumen. To a great extent, these changes in the rumen are due to high concentrations of VFA. The best way to avoid problems with ruminal acidosis is an adequate supply of neutral detergent fiber (NDF) in the diet, preferentially with large particle size and length to stimulate rumination and consequently greater buffering efficiency, thus maintaining the balance between pH and microorganisms in the rumen.

RESUMO.O experimento foi realizado com o objetivo de avaliar as trocas gasosas de genótipos de capim-elefante anão, em diferentes condições hídricas. O delineamento experimental foi inteiramente casualizado com três repetições. Foram avaliados três genótipos de capim-elefante anão (Mott, CNPGL 94-34-3 e CNPGL 92-198-7) em duas condições de umidade do solo: irrigado (I) e não-irrigado (NI). Foi observada diferença entre os tratamentos I e NI para todos os genótipos em relação à taxa fotossintética, condutância estomática, transpiração e déficit de pressão de vapor. O genótipo CNPGL 94-34-3 apresentou maior tolerância ao estresse hídrico, seguido pelos genótipos Mott e CNPGL 92-198-7. Todos os genótipos avaliados apresentaram, em condições ideais de umidade do solo, alta taxa fotossintética, caracterizando, deste modo, os genótipos estudados como plantas de elevada eficiência fotossintética.Palavras-chave: condutância estomática, déficit de pressão de vapor, fotoinibição, fotossíntese, transpiração.ABSTRACT. Photosynthetic characteristics of dwarf elephant grass (Pennisetum purpureum Schum.) genotypes under different hydric conditions. The experiment was carried out aiming to evaluate the gas exchange of dwarf elephant grass genotypes under different hydric conditions, in a randomized design with three replications. Genotypes of dwarf elephant grass (Mott, were analyzed under two hydric conditions: irrigated (I) and non-irrigated (NI). Differences between treatments I and NI were observed for all genotypes for photosynthesis, stomatal conductance, transpiration and water vapor pressure deficit. Genotype CNPGL 94-34-3 presented highest tolerance to hydric stress, followed by genotypes. All genotypes presented high photosynthetic rate, under ideal conditions of soil humidity, thus characterizing the analyzed dwarf elephant grass genotypes as plants with high photosynthetic efficiency.

A great diversity of species of microorganisms are present in the rumen environmental with specific functions in the degradation of carbohydrates, protein and lipids. However, the knowledge of the interactions between the different species of microorganisms in the rumen ecosystem and their specific substrates were used to improve nutritional management and can increase production of meat or milk. A balanced nutritional management is very important. When inappropriate feedstuffs are used on diet formulation for cattle, there is a decrease in the growth of microorganisms in the rumen. And the availability of the use of protein synthesized in rumen for all metabolisms of the animal.

Correspondências devem ser enviadas para: ericozoo1@yahoo.com.br Cameroon presented the largest production of DM, CP, and DDM. There were no significant differences for DM concentration (DM) and leaf/stem ratio (L/S) among the evaluated genotypes. The cluster analyses suggested a group of elephantgrass genotypes with higher DM, CP, and DDM production/ha and other with lower DM, CP, and DDM. Revista Brasileira de Zootecnia

The objective of this study was to determine the effect of the dietary inclusion of lipid-based diets (whole cottonseed and protected fat) on the centesimal composition, fatty acid profile, and sensory properties of meat from finishing Nellore cattle. The study was carried out from August to October 2009. Thirty nine uncastrated Nellore males with average initial body weight of 494.1 ± 10.1 kg and 36 months of age were housed for 63 days in pens with thirteen animals each. A completely randomized design with three treatments and thirteen replications was used. The treatments evaluated were: feed with 2.50% cottonseed (control diet); feed with 11.50 % cottonseed; and feed with 3.13% cottonseed added of protected lipid (PL), all on a dry matter basis. No differences between treatments were observed for moisture, protein, and ash contents. However, the addition of protected fat caused an increase in the percentage of ether extract in the meat. Diets containing cottonseed or protected lipid did not affect fatty acid concentration in the meat. The intensity of the aroma, strange aroma, flavor, strange flavor, juiciness, color, and overall appearance were similar between treatments, except for tenderness, which was positively affected in cattle fed a diet in which the only lipid source was cottonseed. The study demonstrated that the addition of PL in the diets of finishing cattle led to greater levels of intramuscular fat, but to less tender meat than the other treatments.

The use of oil supplies in feed increases the energy density of the diet and has the potential to enhance both animal performance and meat quality. Whole cottonseed is an oilseed that has a high concentration of oil and is especially rich in unsaturated fatty acids such as linoleic acid. Whole cottonseed is considered as an excellent alternative addition to ruminant feed. Protected lipids are composed of industry-based fatty acids. In the feedlot, protected lipids are used in conjunction with calcium and, in certain cases, their addition has been seen to augment meat quality in terms of essential fatty acid concentrations. This review discusses and debates the use of the whole cottonseed as well as protected lipids (calcium salts of fatty acids) as dietary additives to ruminant feed and diet, and also its impact on meat quality. The whole cottonseed and or protected lipids are viable feedlot alternatives for use in feedlot when it is desired to reduce the amount of starch in animal diet without compromising the performance. The addition of the whole cottonseed or protected lipid in diet is not affect pH values in meat. The whole cottonseed does not contribute to the improvement of tenderness of the meat. The proportion mean of Desirable fatty acids in meat in the comparative study were: as pentadecanoic acid (C15:1 = 0.29%), palmitoleic acid (C16:1 = 4.26%), heptadecanoic acid (C17:1 = 0.07%), oleic acid (C18:1n9c = 37.32%), γ-linolenic acid (0.94%) and α-linolenic acid (1.04%), elaidic acid (C18:1n9t = 0.50%), eicosatrienoic acid (C20:3n3 = 0.03%), eicosapentaenoic acid (C20:5n3 = 0.04%), erucic acid (C22:1n9 = 0.89%), docosadienoic acid (C22:2 = 0.04%) and stearic acid (C18:0 = 21.53%). The addition the cottonseed or protected lipid in diet does not affect fatty acids profiles the desirable fatty acids in meat.

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