Ingestive behaviour, herbage intake and grazing efficiency of beef cattle steers on Tanzania guineagrass subjected to rotational stocking managements

Gelson Dos Santos Difante,Valéria Pacheco Batista Euclides,Daniel Oliveira De Lucena Sarmento,Sila Carneiro Da Silva,Roberto Augusto De Almeida Torres Júnior,Domicio Do Nascimento Júnior

doi:10.1590/s1516-35982009000600005

Gelson Dos Santos Difante, Valéria Pacheco Batista Euclides + Show 4 more

Open Access

https://doi.org/10.1590/s1516-35982009000600005

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Abstract

The objective of this experiment was to evaluate the ingestive behaviour, herbage intake and grazing efficiency of beef cattle steers grazing on Panicum maximum Jacq. cv. Tanzania subjected to different rotational stocking intensities. Treatments corresponded to two post-grazing conditions (residues of 25 and 50 cm) associated with a pre-grazing condition of 95% sward canopy light interception during regrowth (LI). The grazing time increased linearly with the duration of the occupation period (475 to 630 minutes/day). On paddocks grazed down to a residue of 25 cm, the bite rate increased linearly along the occupation period, with an average of 42.5 bites/minute. On paddocks grazed down to a residue of 50 cm, the bite rate was stable and equal to 39 bites/minute. There was no difference in herbage intake between grazing intensities. However, grazing at 25 cm residue resulted in greater herbage removal (68.0 vs. 45.6%) and greater grazing efficiency (90.4 vs. 49.8%) than grazing at 50 cm residue. Post-grazing residues of Tanzania guineagrass under rotational stocking management may be set at either 25 or 50 cm, since the herbage intake was not affected within this grazing intensity range. However, herbage removal and grazing efficiency were reduced with the 50 cm post-grazing height and grazing time increased with long occupation periods.

Highlights

The daily amount of dry matter ingested is the most important measurement to allow for inferences regarding animal performance and responses (Burns et al, 1994)
Carvalho et al (2001) argued that the sward structure would have a relatively greater importance than physical and chemiostatic mechanisms of satiety in a pastoral environment, and Da Silva & Carvalho (2005) endorsed that by reporting the high animal performance indexes obtained in recent research on tropical pastures, where control of sward structure was an important feature of the experimental protocols used
Tanzania subjected to different rotational stocking intensities characterized by post-grazing heights of 25 and 50 cm and a common rest period corresponding to the time necessary for swards to reach 95% interception of the incident light during regrowth

Summary

Introduction

The daily amount of dry matter ingested is the most important measurement to allow for inferences regarding animal performance and responses (Burns et al, 1994). The classic hypothesis found in literature is that herbage intake would be controlled by the capacity of the digestive tract to digest low-quality herbage and by the feedback mechanism of the nutrient metabolites absorbed when animals are fed with highly digestible diets. These are called physical and chemiostatic or physiological mechanisms, respectively (Conrad et al, 1964). Cosgrove (1997) stated that it is difficult to predict herbage intake of animals on pastures under any circumstance. Knowledge about the mechanisms involved in the grazing process is important to understand aspects regarding control and regulation of herbage intake on pastures (Romney & Gill, 2000)

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