Dry matter intake of supplemented cattle under grazing during the dry season

Abstract Text: This study aimed to evaluate the dry matter daily intake of cattle supplemented on pasture during dry season. The experiment was conducted in Southwest region of the state of Bahia, Brazil. The study was the growing phase of 36 crossbred steers (Bos taurus x Bos indicus) with initial body weight of 378 kg ± 7.5kg and median age of 14 months. The animals were distributed in a completely randomized design, with four treatments and eight replicates and were managed in an experimental area formed by a Brachiaria brizantha cv.Marandú in a system of intermittent grazing. The supplement was formulated so that the same amount of crude protein (CP%) coming from the supplement was consumed daily by animals in the different treatments. Thus, the treatments were on basis of body weight of animals (% BW): T2 - 0.2%BW with 50% CP, T4 - 0.4%BW with 25% CP; T6 - 0.6%BW with16.67% CP and T8 - 0.8%BW with 12.5% CP. The statistical model used was: Y_ijk = μ + T_i + e_ijk, where: Y_ijk - observed value; μ -  overall constant; T_i -  effect of treatment i and e_ijk – randomized error. There was no difference in the daily intake of total dry matter (tDMI) (P>0.05) between treatments. There was a linear effect (P<0.05) in dry matter intake of forage (fDMI), characterizing a substitutive effect. It is concluded that supplementation of steers in growing phase presents better results when used at low levels, although with a high protein content.

Table 1 – Dry matter intake of supplemented cattle under grazing during the dry season and their respective regression equations and coefficients of determination (R²)

Varibles	Treatment (%BW)				Regression equations	R2
	0.2%	0.4%	0.6%	0.8%
tDMI (kg.day-1)	7.41	7.81	8.18	8.09	-	-
fDMI (kg.day-1)	6.63	6.24	5.79	4.96	Y = 7.27025 - 2.73324X	0.96

Keywords: weight gain, protein supplementation, continuous stocking, substitutive effect