Beef heifers performance in natural grassland under continuous and rotational grazing in the autumn-winter

Abstract

The aim of this study was to evaluate the performance of beef heifers in natural grassland under continuous and rotational grazing during the autumn-winter period. The treatments were distributed in a completely randomized design and conducted using the forage mass above eight cm and 50% of the leaf blades mass of tussocks. The animals were Brangus beef heifers with initial body weight of 258kg. The variables evaluated were available forage mass (FMa), leaf blades mass of tussocks (LBMt), real forage allowance (FAr), sward height of the lower stratum (HLS), crude protein (CP), neutral detergent fiber (NDF), organic matter digestibility (OMD), total digestible nutrients (TDN), average daily gain (ADG), body condition score (BCS), reproductive tract score (RTS) and stocking rate (SR). FMa, HLS, OMD and TDN decreased while FAr, CP and NDF were similar during the experimental period. The ADG was positive only at third experimental period while BCS, RTS and SR decreased over time. The natural grassland management under continuous and rotational grazing during the autumn-winter period, using the forage mass above 8cm and 50% of the leaf blades mass of tussocks, does not allow the adequate corporal development for breeding the beef heifers at 24 months old.

Vegetation composition and forage mass in grassland with a double structure under two winter grazing regimes

“…Vegetation structure o in each treatment did not decrease the live weight of animals during winter as observed by MEZZALIRA et al (2012) and SOARES et al (2015). The ADG was 0.1kg in treatment R and 0.17kg in treatment C (P=0.11).…”

“…Composition of the upper stratum suggested it is possible to guarantee reserves of dry forage matter for use during critical periods. However, the importance of the type of animal for the rate of consumption of such material should be emphasized (SOARES et al, 2015).…”

“…Land ownership reconfiguration has reduced the territorial extent of properties and caused difficulties in maintaining or increasing zootechnical indexes (RIBEIRO & QUADROS, 2015). Suitability of the Pampas grasslands for livestock is also limited in its ability to provide nutrition to animals that have high forage demands (SOARES et al, 2015).…”

“…In natural, sharp, double-structured pastures, estimation of forage mass is complex and sometimes inaccurate. The under-or over-estimation of forage mass stems from unequal distribution of the strata, which makes it difficult to predict exactly what will be consumed by animals, resulting in a low correlation between forage mass allowance and weight gain of live animals (CARVALHO et al, 2015;SOARES et al, 2015). Therefore, to achieve guaranteed animal performance, some farmers have used "forage accumulation" instead of "forage allowance" (TRINDADE et al, 2016).…”

Heifers rearing on natural grassland under rotational grazing during warm season

“…It considers that leaf laminas (leaf) in elongation are the most efficient in terms of photosynthesis, maintaining their nutritional value high both in C3 and C4 species (CONFORTIN et al, 2010;QUADROS et al, 2011). Based on the thermal sum of the LED of dominant grass groups Barbieri et al, (2014) and Soares et al, (2015), this study aimed to evaluate the performance of heifers managed in a grassland under rotational grazing with two rest intervals between grazing.…”