Farelo de soja em substituição à uréia em dietas para bovinos de corte em crescimento e terminação. / Soybean meal as a replacement for urea on growing and finishing beef steers diets.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Two trials were conducted to evaluate increasing diet metabolizable protein levels by soybean meal inclusion, replacing urea, on growing and finishing steers performance. Experiment I: Thirty-six steers, not castrated, (24 Nelore and 12 Canchim), with initial mean weight and age of 230 kg and 15 months, respectively, were assigned to completely randomized block design, according to genetic group, weight and age. Experiment was conducted at the Departamento de Zootecnia at ESALQ/USP, in the Intensive Beef Steers Center Feedlot. Animal were paired on covered pens (3 x 11 m) with concrete floor, feed bulk and waterer, with a total of 18 pens. Experimental period was 84 days (August to December 2001), divided on 4 sub-periods of 21 days. Diets were formulated according to NRC (1996), Level I. Urea treatment (U) contained 2.0% urea and 4.1% soybean meal (DM basis) and presented an excess of 159.4 g/d of rumen degradable protein (RDP). Soybean meal and Urea treatment (FSU) contained of 1.0% urea and 11.5% soybean meal in diet DM and presented an excess of 79.1 g/d of RDP. Soybean treatment FS contained of 18,8% soybean meal in diet DM as a single protein source and supplying almost the exact requirement of RDP (1.0 g/d excess). Treatments had metabolizable energy (ME) and metabolizable protein, respectively, available for average daily gain (ADG) of 1.31 and 1.03, 1.31 and 1.19, 1.33 and 1.42 kg/d for treatments U, FSU and FS, respectively. Simulations were done by the NRC (1996) program, Level I and II, adjusting the observed dry matter intake (DMI). Observed ADG were 1.14, 1.26 and 1.28 kg for treatments U, FSU and FS, respectively. Treatments FSU and FS were not different but were different (P<0.05) compared to Treatment U. Experiment II: Forty steers, not castrated, (24 Nelore and 16 Canchim), with initial mean weight and age of 400 kg and 20 months, respectively, were assigned to completely randomized block design, according to genetic group, weight and age. Experiment was conducted at the Departamento de Zootecnia at ESALQ/USP, in the Intensive Beef Steers Center feedlot. Animal were paired on covered pens (3 x 11 m) with concrete floor, feed bulk and waterer, with a total of 20 pens. Experimental period was 84 days, divided on 4 sub-periods of 21 days. Diets were formulated according to NRC (1996), Level I , to have a rumen degradable protein (PDR) balance higher than 80g/d and metabolizable energy to assure a average daily gain (ADG) of 1.40 kg on all treatments. Treatment U contained of 2.11% urea on diet DM as the main source of protein and metabolizable protein available for an ADG of 1.75 kg/animal. Treatment FS contained of 7.03% soybean meal and 1.01% urea in diet DM and metabolizable protein available for an ADG of 2.09 kg/animal. Dry matter intake (DMI) was not affected by treatments (P<0.05), with values of 12.1 kg DM/d and 12.5 kg DM/d for Treatment U and FS, respectively. ADG was higher (P<0.05) for animals receiving the higher metabolizable protein diet (FS: 1.46 kg/d) as compared to the lower metabolizable protein diet (U: 1.29 kg/d).

ASSUNTO(S)

uréia dieta animal bovino de corte desempenho animal animal performance animal diet soybean meal cattle urea farelo de soja

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