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CONTENIDO DE ENERGIA ESTIMADA PARA E.L CRECIMIENTO DEL GANADO BOVINO, EN LOS FORRAjES DEL TROPICO HUMEDO DE COSTA RICA 1

ABSTRACT La produccion de ganado de carne y lechero Estimated energy levels for growing en el tropico hurnedo de Costa Rica se basa en el cattle, in grasses of the humid tropics of uso intensivo de pasturas, y se caracteriza porque Costa Rica. Beef and dairy cattle production in los animates tienen indices de crecimiento media- the humid tropics of Costa Rica is based upon nos 0 bajos. Para estimar el contenido de energfa intensive grazing, and is characterized by neta de las principales especies de grarnfneas forra- animals with medium and low growth rates. To jeras de la region, se tomo un total de 190 muestras estimate net energy content of main grass durante un ano. Las muestras fueron tomadas simu- species in the region, a total of 190 hand-pucked lando pastoreo en fincas comerciales de los distritos samples was taken during a year period in de Florencia y Fortuna del Canton de San Carlos. commercial farms in the Florencia and Fortuna Las especies evaluadas fueron Estrella Africana Districts, San Carlos county. Grasses analyzed (Cynodon nlemfuensis), Brachiaria Ruzi (Brachia- were Cynodon nlemfuensis, Brachiaria ria IUziziensis), Ratana (/schaemun indicum), Can- ruziziensis, /schaemun indicum and Pennisetum delario (Pennisetum purpureum cv King Grass), co- purpureum cv King Grass, they were harvested sechadas a edades de rebrote de 21-25, 26-30, 21- at maturity stages of 21-25,26-30,21-25 Y 45- 25 Y 45-55 dfas, respectivamente. Los contenidos 55 days, respectively. Net energy for de energfa neta de mantenimiento (ENM) y energia maintenance and NEG contents were estimated neta de ganancia (ENG) fueron calcu1ados segun las using methodologies proposed by Weiss (1997) metodologfas de Weiss (1997) y NRC (1989, and NRC (1989, 1996). Both variables differed 1996). Ambas variables diflrieron entre especies, (P~0.05) among grass species. However, season sin embargo solo en Florencia se encontraron dife- effect was only found in Florencia District. rencias entre epocas climaticas. En Florencia los Estimated NEM contents in C. nlemfuensis, B. contenidos de ENM en los pastos Estrella Africana, ruziziensis and /. indicum in Florencia were Brachiaria Ruzi y Ratana fueron 1.10; 1.17 y 0.98 1.10, 1.17 and 0.98 Mcal/kg of DM, respec- Mcal/kg de MS, respectivamente; rnientras que los tively; while NEG were 0.55, 0.60 and 0.43 contenidos de ENG fueron 0.55; 0.60 y 0.43 Mcal/kg of DM. In Fortuna C. nlemfuensis, B. Mcal/kg de MS. En la Fortuna los pastas Estrella ruziziensis, /. /ndicum and P; purpureum cv Africana, B. Ruzi, Ratana y Candelario mostraron King Grass showed values of 1.12, 1.05, 0.98

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    ABSTRACT: With the objective of evaluating the effect of methionine supplementation prior to a breeding program, thirty one heifers (Bos taurus x Bos indicus) were used averaging 386 +/- 29 days of age and a mean body weight of 402.6 +/- 28 kg. Fifteen of the animals received a supplement (SG) during 45 days with molasses-urea mixture (2 kg molasses + 407 g urea/head/day), plus 10 g of ruminally protected methionine. The other sixteen heifers did not receive supplement (CG). Fecal and pastures samples were collected to assess dry herbage intake and digestibility. Serial ultrasound measurements from the ovary were performed in both groups to evaluate follicular dynamics. The heifers were categorized according to their follicular size and presence of a CL. Forage intake and dry matter digestibility were reduced (P < 0.05) and body condition tended to improve (P = 0.07) in the supplemented heifers, however, total intake, final weight, daily gain and dorsal back fat were not affected. After the supplementation period, the percentage of females in the categories < 3 mm and 3 to < 6 mm, was greater (P < 0.05) in CG (25% and 43.7%) that in SG (0% and 26.6%) but in the follicle category of > or = 9 mm, the percentage of animals was 60% in SG and 18.8% in CG (P < 0.05). The percentage of ovulation for the SG and CG was 86.7% and 62.5%, respectively (P < 0.05). The combination of supplementation with methionine-urea and molasses at the end of the dry season and the anticipated onset of the rainy season favored the establishment of ovarian activity and follicular dynamics.
    Tropical Animal Health and Production 12/2008; 40(8):667-72. · 1.09 Impact Factor

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