Effect of replacing Tifton 85 haylage with sorghum silage on intake and digestibility of nutrients and performance of beef cattle

Avaliaram-se o consumo e a digestibilidade dos nutrientes, o ganho de peso (GMD) e a convers?o alimentar (CA) em bovinos de corte recebendo dietas ? base de silagem de sorgo (SS) e pr?-secado de capim-tifton 85 como volumoso, nas seguintes propor??es: 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 rela??o volumoso:concentrado de 60:40, na MS. Foram utilizados 24 animais mesti?os Holand?s x Zebu n?o-castrados (360 kg de PV) distribu?dos em um delineamento em blocos casualizados. Ap?s um per?odo de adapta??o de 15 dias, foram realizados tr?s per?odos experimentais de 28 dias. Para determina??o da excre??o fecal, utilizou-se a fibra em detergente ?cido indigest?vel (FDAi) como indicador. Os consumos m?dios di?rios de MS, MO, PB, EE, CT e NDT, em kg/dia, n?o foram influenciados pelas dietas, registrando-se valores m?dios 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 quadr?tica pelo n?vel de SS no volumoso, estimando-se digestibilidades m?nimas de 60,33; 61,58; 61,89 e 55,83% nos n?veis de 44,80; 47,18; 50,95 e 51,21% de silagem de sorgo, respectivamente. O GMD e a CA foram influenciados de forma quadr?tica pelos n?veis de SS e apresentaram valores m?ximos e m?nimos de 1,25 kg/dia e 7,66 para os n?veis de 60,95 e 67,04% de SS, respectivamente. O uso de silagem pr?-secada de capim-tifton 85 associada ? silagem de sorgo consistiu em boa alternativa de volumoso para termina??o de bovinos de corte. A inclus?o de aproximadamente 60% de silagem de sorgo no volumoso promoveu m?ximo ganho de peso estimado.Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Empresa de Pesquisa Agropecu?ria de Minas Gerais (EPAMIG)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)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, respectively. Mean daily weight gain and feed conversion also were affected quadratically by increasing the level of sorghum silage in the forage portion of the diet with estimated maximum and minimum values of 1.25 kg/day and 7.66 for the levels of 60.95 and 67.04% of sorghum silage, respectively. Results indicated that varying dietary ratios of Tifton 85 haylage and sorghum silage is a good alternative for feeding forage to finishing beef cattle. Inclusion of approximately 60% of sorghum silage in the total dietary forage resulted in the greatest estimated weight gain