Intake and digestibility in cattle fed low-quality tropical forage and supplemented with nitrogenous compounds

Abstract

-The objective of this study was to evaluate the effects of supplementation with nitrogenous compounds on intake, digestibility, and rumen microbial synthesis in cattle fed low-quality tropical forage. Five crossbred heifers, averaging 209 kg and fitted with ruminal fistulla, were used. The animals were fed ad libitum with signal grass (Brachiaria decumbens Stapf.) hay, which had crude protein (CP) content of 5.08%, as dry matter (DM) basis. The five treatments were defined according to the increasing level of CP in the diet (0, 3, 5, 7, and 9 percentile points above the forage CP level). The supplement consisted of the following nitrogen sources: urea, ammonium sulfate and albumin (4.5:0.5:1.0, respectively). The experiment was carried out according to a 5 × 5 Latin square design, with five experimental periods. The average CP levels in the diets were: 5. 28, 8.08, 9.82, 11.87, and 13.63% on DM basis. The intakes of DM, organic matter (OM), and neutral detergent fiber (NDF) showed a quadratic response according to CP levels in the diet, with maximum responses at 10.83%, 10.78%, and 10.37% CP, respectively. The digestibility coefficients of OM and NDF showed a linear-response-plateau response according to CP levels, with the plateau beginning (maximum response) at 7.93% and 7.55% CP, respectively. The average daily concentration of rumen ammonia nitrogen (RAN) was positively related with CP levels. The RAN estimate associated with the maximum DM intake was 15.33 mg/dL. It was observed that intestinal flow of microbial nitrogenous compounds and nitrogen intake became equivalent to each other at 7.13% of CP. 8,08; 9,82; 11,87 e 13,63%, com base na matéria seca (MS). Verificou-se efeito quadrático dos níveis de PB na dieta sobre os consumos de MS, matéria orgânica (MO) e fibra em detergente neutro (FDN) (kg/dia), com respostas máximas nos níveis de 10,83%, 10,78% e 10,37% de PB, respectivamente.

Replacement of soybean meal by cottonseed meal 38% in multiple supplements for grazing beef heifers

“…Neutral detergent fiber levels in diet were estimated according to recommendations by Mertens (2002). The corrections regarded to protein levels and ash in neutral detergent fiber were conducted following recommendation by Licitra et al (1996) and Mertens (2002), respectively.…”

Consumo, tempo de pastejo e desempenho de novilhos suplementados em pastos de Brachiaria decumbens, durante o período seco

“…Nesse caso, recomenda-se a suplementação protéica para se aumentar a concentração de N-amoniacal no rúmen, a fim de se potencializar o consumo de forragem (GOES et al, 2010). Lazarinni et al (2009) Suplementando tourinhos em fase de recria, no período da seca, Porto et al (2011) verificaram que houve menor participação do pasto como fonte de energia à medida que aumentava o fornecimento de suplemento, evidenciando que as menores ofertas de suplemento e os altos teores de PB em suplementos múltiplos de baixo consumo propiciam maior uso da forragem como fonte de energia, ou seja, maior consumo da dieta basal, recomendando que a suplementação para baixo consumo (aproximadamente 0,2% do PV) pode ser fornecida aos tourinhos em fase de recria durante o período da seca para estimular o consumo de pasto, porém a máxima produção microbiana é obtida com ofertas medianas de suplementos (aproximadamente 0,5% do PV).…”

Effect of protein supplementation on ruminal parameters and microbial community fingerprint of Nellore steers fed tropical forages

“…However, the availability of foods for ruminants in the tropics varies depending on seasonality, with a distinct dry period and a rainy period (Figueiras et al, 2010;Costa et al, 2011). In the dry period (AprilSeptember), the tropical forages available for animal feeding show a high fiber and lignin content and the levels of CP are often <7%, a value considered limiting for microbial protein synthesis by ruminal microorganisms (Lazzarini et al, 2009;Figueiras et al, 2010). In the rainy period (October-March), the forages have a more adequate CP content (16%), but the synthesis of microbial protein is still limited because of the high degradability of the CP in the forages (Costa et al, 2011).…”

“…In the rainy period (October-March), the forages have a more adequate CP content (16%), but the synthesis of microbial protein is still limited because of the high degradability of the CP in the forages (Costa et al, 2011). Supplementation is the main strategy for avoiding these limitations and adjusting the nutritional imbalance in tropical pastures, being a common practice in dairy and beef farming (Lazzarini et al, 2009).…”