The effects of phosphate and nitrogen fertilization on aspects of forage composition and ruminal fermentation were separately evaluated pre- and post-grazing, in addition to the dry matter intake and weight gain of sheep grazing Panicum maximum cv. Massai under a rotational system on Quartzipsamment soil. The aim was to evaluate the effect of fertilization with different levels of phosphorous (50 and 200 kg P2O5/ha) and nitrogen (100 and 400 kg N/ha) compared to unfertilized control soil. The experiment was conducted at the School of Veterinary Medicine and Animal Science at Universidade Federal do Tocantins – UFT, in a randomized complete block design with four replicates in a factorial 2 × 2 design. The study area consisted of 32 paddocks (301 m²), each of which had previously been sown with Panicum maximum cv. Massai. The experimental area was managed under intermittent stocking with a variable stocking rate. Twenty-eight crossbreed sheep were used for grazing management. Evaluations were made before and after grazing, including forage evaluation and measurement of ruminal degradability and intake (using titanium dioxide as the external marker). Regarding the forage composition, a significant difference (P < 0.05) was observed between the control and fertilizer treatments for neutral detergent fiber (NDF), acid detergent fiber, crude protein, lignin and phosphorous content. Fertilization was found to alter the nutritional quality of Panicum maximum cv. Massai grass. Among the nutritional aspects evaluated, fertilization influenced NDF, grass digestibility and dry matter intake. The forage composition of Massai grass is improved by fertilization with nitrogen at 100 kg N/ha and phosphate up to 50 kg P2O5/ha, which represents a relevant management practice for increasing quantity and quality.
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.
SUMMARY This studyaimed to assess the influence of three pre-grazing heights of Massai grass on the ingestive behavior of sheep under rotational stocking. Eighteen Dorper x nondescript crossbred sheep were used under rotational stocking on Massai grass at pre-grazing heights. The animal stocking was estimated to ensure a reduction of approximately 50% of the initial height. Behavior assessments were performed from 6 to 18 h at the entrance and exit of animals from paddocks. The longest activity was grazing, followed by rumination and other activities, and the period from 6 to 10 h showed the longest grazing.In the other periods, the animals in the 35-cm treatment grazed less when compared to those ofthe other treatments. Rumination in all treatments was more significant in the period from 14 to 18 h, but the animals in the 45-cm treatment spent more time doing this activity, which gave them a higher time of rumination of the food bolus, as well as ruminating chews. The bite rate was higher for the 25-cm treatment, followed by the 45 and 35-cm treatments, respectively.
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