Short-term evaluation of Massai grass forage yield and agronomic characteristics and sheep performance under rotational grazing with different pre-grazing canopy heights

Abstract

This study aimed to evaluate the morphogenic, structural, chemical characteristics, and forage yield of Massai grass, as well as the performance of sheep under three pre-grazing canopy heights. Eighteen Dorper x crossbred sheep (12 males and 6 females) were subjected to three pre-grazing canopy heights of Massai grass (45, 35, and 25 cm). Rotational grazing was adopted, with a fixed rest period of 12 days and occupation of four days. Before placing animals in the paddock, stocking rate was estimated to ensure a reduction of about 50% in the initial height. Morphogenic and chemical characteristics of forage were evaluated, as well as animal intake and performance. Pasture managed at 25 cm height induced reductions in stem and sheath sizes, and phyllochron but an increased leaf: stem ratio. However, the pasture cut at 35 cm above ground promoted an increase in total dry mass and foliar leaf productions, in addition to greater forage availability and daily accumulation. Yet, pastures with a height of 45 cm had a higher percentage of stem and senescent material, decreasing leaf intake by animals. Among the studied heights, 35 cm is the most suitable for Massai grass, when used for rearing sheep for meat production under pasture conditions in the northern Tocantins. This is because this management provided a greater availability of good quality forage and thereby increasing weight gains per area in animals.

Performance supplementation and ingestive behavior of sheep finished in continuous pasture in the period of water restriction

“…Acta Scientiarum. Animal Sciences, v. 44, e53855, 2022 The available forage mass was 3203.13 kg ha -1 and the forage supply 6.65% with the grass being pastured between the canopy heights of 35.58 and 13.67 cm, close to the values obtained with the management being done at the same heights during the rainy season (Cardoso et al, 2019), this demonstrates that the adequate management carried out in the waters influences the mass of forage available in the months of low rainfall.…”

“…in Massai grass in dry and rainy periods and fertilized with 200 kg ha -1 of N.The values of acid detergent fiber (ADF) and neutral detergent fiber (NDF) were close to those obtained byCardoso et al (2019) (38.4 and 77.9% of DM) andSilva et al (2017) (80.04 and 45.39% of DM) in the same area of Massai grass in the rainy season. The same occurred for TDN levels close to 50.15% obtained byCardoso et al (2019).…”

“…Silva et al (2017) evaluating doses of up to 100 kg ha -1 and 50 kg ha -1 of N and P2O5 respectively, in the same area of Massai grass where this experiment was carried out, found CP values of 7.06% in the water period, close to the 7.03% observed by Costa et al (2017) The production and structure of the pasture did not present difference for the evaluated treatments, indicating that the management adopted in the pasture was the same in the used area. Managing Massai grass height at 35.58 cm, the dry mass production was 5512.41 kg ha -1 (Table 4), a value lower than the forage mass production obtained in this same area in the water period (6600 kg ha -1 ) with similar management and fertilization height (Cardoso et al, 2019), which was expected due to the low precipitation of this time (Table 1). However, the value of forage mass was higher than the 2694 kg ha -1 found by Gurgel et al (2017) working with Massai grass with 95% light interception in the water restriction period of the year and the 3971 kg ha -1 observed by Emerenciano Neto et al (2016) in Massai grass fertilized with urea (150 kg ha -1 of N) and use of irrigation in the months without rainfall.…”