Resumo

BERETTA, Virginia; SIMEONE, Álvaro  e  BENTANCUR, Oscar. Shade Managment Associated to Grazing Restriction: Effect on Cattle Behaviour and Summer Performance. Agrociencia Uruguay [online]. 2013, vol.17, n.1, pp.131-140. ISSN 1510-0839.

This study assessed the effect of shade and restriction of time of access to grazing on animal performance and grazing behaviour during summer. Thirty two Hereford steers (313.2±36.2 kg) were randomly allocated to two grazing managements on grass and legume mixed pastures during two consecutive summers: restricted grazing (RG, between 10:00 am and 5:00 pm animals were moved out from the pasture paddock to a shaded area); or free grazing (FG, animals remained all day long in the grazing paddock, without shade). Cattle strip-grazed independent paddocks per treatment with a forage DM allowance of 6 kg DM/ 100 liveweight (LW). RG improved LW gain (0.875 vs. 0.998 kg/day; SE 0.037, P=0.0197) without affecting intake (FG: 3.04 vs. RG: 2.88 kg/100 kg LW; SE 0.141, P>0.10) or selectivity (P>0.10). Grazing activity was higher in RG (0.55 vs. 0.75, P<0.001), while rumination and idling were both reduced (P<0.01) without differences in bite rate (P>0.10) with respect to FG. This response probably contributed to keep consumption stable in spite of reduced time of access to pasture. An estimated reduction in MEm requirements (27.3%) would explain the observed improvement of the energy balance in RG compared to FG.

Palavras-chave : RESTRICTED GRAZING; INTAKE; HEAT STRESS.

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