INTERACTION BETWEEN GRAZING MANAGEMENT AND ENERGY SUPPLEMENTATION ON BEHAVIOR OF GRAZING BEEF CATTLE

Abstract Text:

The objective of this study was to evaluate the effects of two grazing managements, based on canopy height, and two levels of energy supplementation on ingestive behavior of beef cattle grazing an intensively managed tropical grass. Treatments were two pre-grazing heights (25 cm and 35 cm) both managed with stubble height corresponding to 60% of the pre-grazing height (15 cm and 21 cm, respectively) combined with two levels of energy supplementation (0 and 0.6% BW of fine ground corn). Eight 36 month-old cannulated Nellore steers (487 kg BW ±6.96 kg) were assigned to two 4x4 Latin squares and allocated in 2 hectares of Brachiaria brizantha pasture. Animals were monitored every 5 minutes during 24 hours to evaluate the ingestive behavior, according to the activities: grazing, rumination and idle. Bite rate was also evaluated. Grazing time was not affected by the managements (P>0.05), however decreased (P<0.05) with the energy supplementation (72.5 min). Both, management and supplementation did not affect rumination and bite rate (P>0.05). Time spent in idle was increased (P<0.05) by energy supplementation (100.62 min). The managements based on 60% of the pre-grazing height did not affect DMI.

Table 1 – Grazing time, rumination, idle and bite rate of beef cattle grazing tropical grass

	Management, cm		Supplementation, % of BW		P value			SEM
Activities	25 - 15	35 - 21	0	0,6	M	S	M*S
Grazing1	292.19	295.94	330.31	257.81	0.8652	0.0032	0.9323	42.9
Ruminantion1	322.5	349.37	350	321.87	0.2497	0.2290	0.9350	42.2
Idle1	735.31	704.69	669.69	770.31	0.4379	0.0168	0.9238	73.52
Bite rate2	28.79	29.02	28.05	29.76	0.8968	0.3535	0.3962	2.49

(1)minutes; (2)bite/minute.

Keywords: Supplementation; Beef cattle; Marandu palisadegrass; Ingestive behavior