Animal performance and sward characteristics of two cultivars of Brachiaria brizantha (BRS Paiaguás and BRS Piatã)

Nayana Nazareth Nantes,Valéria Pacheco Batista Euclides,Cacilda Borges Do Valle,Rodrigo Amorim Barbosa,Denise Baptaglin Montagner

doi:10.1590/s1806-92902016000300001

Abstract

The objective of the present study was to evaluate live weight gain per animal and per area and its relationship with the characteristics of pastures of Brachiaria brizantha cv. Paiaguas and Piata. A randomized blocks experimental design was used, with two treatments and six replicates. The experimental area was 8.0 ha, divided into twelve paddocks of 0.67 ha. The grazing method used was continuous stocking, with variable stocking rate. Three tester steers were used per paddock. Sward heights were measured once a week, and the stocking rate (SR) was adjusted using regulator steers to maintain the sward height at 30 cm. Pasture samples were collected once a month, and herbage accumulation rate (HAR), percentage of leaves (PL), leaf:stem ratio (LSR), and nutritive value (NV) were determined. Animals were weighed every 28 days. No differences between the two cultivars were observed during the wet season for any of the evaluated parameters. However, cv. Paiaguas presented higher HAR and, consequently, higher SR than cv. Piata during the dry season. As a result of its higher regrowth, cv. Paiaguas pastures presented significantly higher PL, LSR, and NV and, consequently, significantly higher average daily live weight gain. These differences resulted in higher live weight gain per area for Paiaguas grass (695 kg/ha per year) than for Piata grass (645 kg/ha per year). Thus, Brachiaria brizantha cv. Paiaguas is a good alternative to decrease the temporary forage shortage and for the diversification of pastures in the Cerrado biome region.

Highlights

One of the factors responsible for low beef cattle production in the tropics is inadequate animal nutrition, resulting mainly from the seasonality of forage production, which is characteristic of tropical regions
The sward heights of Paiaguás and Piatã cultivars remained within the target range during the wet season (Table 1)
Significant interactions between the cultivar and the season of the year were observed for herbage accumulation rate (HAR; P = 0.0431), percentage of leaves (PL; P = 0.0321), leaf:stem ratio (LSR; P = 0.0411), crude protein (CP; P = 0.0459), in vitro organic matter digestibility (IVOMD; P = 0.0241), stocking rate (SR; P = 0.0334), and average daily gain (ADG; P = 0.0257)

Summary

Introduction

One of the factors responsible for low beef cattle production in the tropics is inadequate animal nutrition, resulting mainly from the seasonality of forage production, which is characteristic of tropical regions. Any effort to increase the availability of quality forage during the dry season will contribute significantly to increasing cattle farming productivity. In spite of the great effort of research institutions for the release of new cultivars, the number of cultivars effectively used is still small, and these few cultivars occupy large areas, generating vulnerability in the production systems due to biotic and abiotic factors (Valle et al, 2009; Jank et al, 2011). The seasonality of forage production will still be a limitation present in all scenarios (Deconto, 2008), requiring new strategies to meet the animal nutritional demands for the longest period possible

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