We used chemical composition and in vitro digestibility data from temperate and tropical forages to develop relationships between indices of lignification and forage indigestible NDF. Neutral detergent fiber indigestibility increased nonlinearly as the lignin concentration of the NDF increased. Differences in estimated indigestible NDF using equations developed for a specific forage class (C3 and C4 grasses and legumes) were small and are probably not biologically significant when compared to those estimated from a common equation. Selected equations were compared with the Cornell Net Carbohydrate and Protein System (CNCPS) for the prediction of ADG. The linear equation (2.4 times NDF lignin content) used by the CNCPS and the Beef NRC had some of the largest errors due to mean bias. A log-log model [4.37 x (lignin/NDF)(.84)] provided the best combination of low total prediction error, low mean bias, and minimal error due to regression bias when permanganate lignin was used. A similar equation based on sulfuric acid lignin [6.17 x (lignin/NDF)(.77)] also met the above criteria. These equations then were evaluated with the CNCPS model against animal growth data from diets ranging in forage quality. Regardless of the equation used for predicting unavailable fiber, the CNCPS underpredicted daily gain, with mean biases ranging from -.10 to -.22 kg/d. Regression bias ranged from .13 to .14 kg/d and the coefficients differed from unity (P = .0001). The new equations gave numerically lower energy allowable ADG by steers compared to the linear equation currently used by the CNCPS model. The estimates were lower due to a higher predicted indigestible NDF, which resulted in a lower estimated forage energy value.

No abstract

The nutritional characteristics of an alga ( Microcystis sp.) that occurs naturally in a Guatemalan lake were determined. The sun-dried material proved to have a high protein content (55.6%) and to be a possible good source of calcium and phosphorus (1, 169.1 and 633.4 mg/100 mg, respectively). Amino acid analysis showed that total sulfur amino acids were the most deficient ones, giving a protein score of 42 to the material. The in vitro protein digestibility of the material was 69.5%. Biological trials demonstrated that when the material was offered as the only protein source, very low consumption and a high mortality rate were obtained whether or not the diet was supplemented with 0.4% dl -methionine. However, when the material supplied 25% of the total protein of a corn-algae diet, the protein quality of the cereal was significantly improved ( P < 0.05).

Com o objetivo de avaliar o desempenho de cultivares de soja dos ciclos precoce, semiprecoce e médio em Latossolos Vermelhos com diferentes classes texturais, realizou-se experimento no município de Naviraí-MS, no ano agrícola 2008/2009. Adotou-se delineamento experimental em blocos inteiramente casualisados, com quatro repetições. Os cultivares de soja utilizados foram CD 202, CD 208 e CD 214RR de ciclo precoce, BRS 239, BRS CharruaRR e BRS 245RR de ciclo semiprecoce, além dos cultivares CD 219RR e Monsoy 8001 de clico médio. A semeadura foi realizada em novembro de 2008, em sistema de plantio direto sobre a resteva de milho. Foram avaliados os parâmetros número de vagens por planta, número de grãos por vagens, peso de mil grãos e produtividade. Independente da classe textural do solo, a fertilização e manutenção de médios a altos teores de nutrientes nos Latossolos Vermelhos Eutróficos de textura média a muito argilosa possibilita a expressão fenotípica de altas produtividades agrícolas de grãos pelas cultivares de soja.