Efeito da substituição de pré-secado de capim-tifton 85 por silagem de sorgo no consumo e na digestibilidade dos nutrientes e no desempenho de bovinos de corte

Abstract

RESUMO -Avaliaram-se o consumo e a digestibilidade dos nutrientes, o ganho de peso (GMD) e a conversão alimentar (CA) em bovinos de corte recebendo dietas à base de silagem de sorgo (SS) e pré-secado de capim-tifton 85 como volumoso, nas seguintes proporções: 0:100; 32:68; 66:34 e 100:0, respectivamente, com base na MS. As dietas (isonitrogenadas) foram formuladas para conter aproximadamente 12% de PB, adotando-se uma relação volumoso:concentrado de 60:40, na MS. Foram utilizados 24 animais mestiços Holandês x Zebu não-castrados (360 kg de PV) distribuídos em um delineamento em blocos casualizados. Após um período de adaptação de 15 dias, foram realizados três períodos experimentais de 28 dias. Para determinação da excreção fecal, utilizou-se a fibra em detergente ácido indigestível (FDAi) como indicador. Os consumos médios diários de MS, MO, PB, EE, CT e NDT, em kg/dia, não foram influenciados pelas dietas, registrando-se valores médios de 9,46; 9,05; 1,20; 0,52, 7,4 e 6,23 kg/dia, respectivamente. As digestibilidades aparentes da MS, MO, PB e EE foram influenciadas de forma quadrática pelo nível de SS no volumoso, estimando-se digestibilidades mínimas de 60,33; 61,58; 61,89 e 55,83% nos níveis de 44,80; 47,18; 50,95 e 51,21% de silagem de sorgo, respectivamente. O GMD e a CA foram influenciados de forma quadrática pelos níveis de SS e apresentaram valores máximos e mínimos de 1,25 kg/dia e 7,66 para os níveis de 60,95 e 67,04% de SS, respectivamente. O uso de silagem pré-secada de capim-tifton 85 associada à silagem de sorgo consistiu em boa alternativa de volumoso para terminação de bovinos de corte. A inclusão de aproximadamente 60% de silagem de sorgo no volumoso promoveu máximo ganho de peso estimado.Palavras-chave: confinamento, conversão alimentar, rendimento de carcaça, volumoso Effect of replacing Tifton 85 haylage with sorghum silage on intake and digestibility of nutrients and performance of beef cattleABSTRACT -Intake, digestibility of nutrients, daily weight gain, and feed conversion were evaluated in beef cattle receiving diets containing the following ratios of sorghum silage:Tifton 85 haylage: 0:100; 32:68; 66:34; and 100:0. Diets were formulated to be isonitrogenous (12% crude protein) with a forage:concentrate ratio of 60:40, on DM basis. Twenty-four crossbred Holstein x Zebu steers averaging 360 kg of initial body weight were distributed in a completely randomized block design with 15 days for diet adaptation followed by three experimental periods of 28 days each. Indigestible acid detergent fiber (IADF) was used to estimate fecal output. Mean daily intakes of DM, OM, CP, EE, TC, and TDN all were not affected by treatments with mean values of: 9.46, 9.05, 1.20, 0.52, 7.4, and 6.23 kg/day, respectively. Significant quadratic effects were observed for the apparent total tract digestibilities of DM, OM, CP, and EE with estimated minimum digestibilities of 60.33, 61.58, 61.89, and 55.83% for the levels of 44.80, 47.18, 50.95, and 51.21% of sorghum silage in the forage portion of the diet, respe...

Intake, digestibility, ruminal parameters, and microbial protein synthesis in crossbred steers fed diets based on Brachiaria grass silage and sorghum silage

“…Thus, the maximum intake of NDF was 1.01% BW with 66.1% of sorghum silage in the diet forage. Souza et al (2006) fed steers with different proportions of Tifton-85 haylage and sorghum silage and observed increase on intake of EE and NFC when sorghum silage was added to the diets. On the other hand, Feijó et al (2001) evaluated the effect of grass (Panicum maximum) and sorghum silages on the performance of Nellore cows and observed greater DMI by cows fed sorghum silage than grass silage (2.8 and 2.2% of BW, respectively).…”

“…Adoption this feeding strategy offers the potential to increase productivity due to the associative effects of mixed-forage diets on nutrient supply to cattle (Phipps et al, 1995;Wilkinson et al, 1998). Previous studies with beef (Souza et al, 2006) and dairy cattle (Ferreira et al, 1995;Phipps et al, 1995;O'Mara et al, 1998) have shown increased intake of forage when corn silage or sorghum silage has been incorporated into diets based on grass silage as the sole forage. However, grass silage of Brachiaria brizantha, a common grass in the tropical regions, has not been evaluated.…”

Sulfur sources in protein supplements for ruminants

“…The NRC (2001), on the other hand, considered the concentration 5 mg/100 mL an adequate condition for digestion of organic matter. Souza et al (2006) estimated maximum ruminal ammonia of 13.14 mg dL -1 , with 2.9 hours after feeding on diets with pre-dried Tifton 85 Bermuda grass and sorghum silage. Pereira et al (2007) estimated maximum ruminal ammonia concentration of 14.89 mg dL -1 with 2.39 hours after feeding by cattle fed sorghum silage with 40% concentrate.…”

Tifton 85 bermudagrass (Cynodon sp.) silage as a replacement for Tifton 85 hay to feed lactating cows

“…is a hybrid strain of bermudagrass selected from the cross of Tifton 68 grass (Cynodon nlemfuensis Vanderyst) with an introduction from South Africa, registered as PI 290884 (Cynodon dactylon [L.] Pers) (Burton et al, 1993). This cultivar presents a rapid growth rate and good digestibility (Castro et al, 2010), as well as thin stems and, thus, can be used for production of hay and silage (Souza et al, 2006).…”