&lt;b&gt;Ingestive behavior of crossbred heifers in four seasons related to the structure of stargrass pasture

Ludmila Lacerda Campana,Sérgio Traballi Camargo Filho,Ana Carolina Carvalho De Barros,Elisa Cristina Modesto,Carlos Augusto Brandão De Carvalho,Pablo Gilliardi Zanella

doi:10.4025/actascianimsci.v37i1.24787

Abstract

The ingestive behavior of crossbred heifers grazing on stargrass pasture was managed at two levels of light interception and two levels of post-grazing residual height. The experiment was conducted at Pesagro (Seropedica, Rio de Janeiro State) between April 2012 and January 2013. The grazing (GT), rumination (RT) and idling (IT) times were evaluated every 10 minutes throughout a 24-hour period. Forage samples were collected for the analysis of chemical composition and for leaf:stem ratio determination. Dry bulb, wet bulb and black globe temperatures were evaluated every hour along with the relative humidity, during grazing to characterize the environment and calculate the Black Globe Humidity Index (BGHI). The mean grazing time (6 hours) was inversely related to sward height. The rumination time was associated with lignin content, in autumn and spring. The mean idle time (9 hours) was related to the grazing time. Animals became tolerant to climatic variations, as GT, RT and IT showed no temporal variations. On the other hand, the sward structure and its chemical characteristics showed greater influence on the ingestive activities of cattle grazing on pasture.

Highlights

Animal behavior can be defined as any and all types of action of an animal, whether perceptible or not, to the human sensory system (Lawrence, 2008), that occurs as a voluntary or involuntary pattern of action (Maggioni et al, 2009).Throughout grazing behavior the animal shows characteristics of its pastoral environment
This study aimed to evaluate the ingestion behavior of crossbred heifers on stargrass pasture managed at two levels of light interception and two levels of post-grazing residual height during the autumn, winter and spring of 2012 and summer 2013, in Baixada Fluminense, Rio de Janeiro State
Grazing intervals corresponded to the period of time necessary for the forage canopy to reach 90 to 95% of incident light interception (LI) during regrowth

Summary

Introduction

Animal behavior can be defined as any and all types of action of an animal, whether perceptible or not, to the human sensory system (Lawrence, 2008), that occurs as a voluntary or involuntary pattern of action (Maggioni et al, 2009).Throughout grazing behavior the animal shows characteristics of its pastoral environment. Ingestive activities of cattle are concentrated in discrete periods during the day, heterogeneously distributed over the circadian period (Fischer et al, 2002; Silva et al, 2008), and climate and feeding are some of the factors that affect the behavior of these animals (Grant & Albright, 1995). Another determining factor in the ingestive behavior of ruminants while grazing is the structure of the forage

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