This study aimed to evaluate the effect of three herbage allowances (5, 10, and 15 kg dry matter [DM] 100 -1 of body weight [BW]) for Brachiaria brizantha cv. Marandu pastures in a continuous grazing system on the morphological and nutritional characteristics of forage, animal performance, and economic viability in Nellore heifers. The total experimental area was 60 ha, divided into 12 paddocks of 5 ha each, with 4 paddocks per treatment. The experimental animals were Nellore heifers (260 in total), with average BW of 301.16 ± 9.12 kg, receiving 0.4 % BW in multiple supplements. We evaluated the production, structural characteristics, and nutritional value of the forage, productive performance, carcass characteristics, and economic viability of each allowance. There were significant effects for the production, structural characteristics, and nutritional value of the forage treatment. The proportions of leaves were 42.40, 38.20, and 30.88 % and the leaf:stem ratios were 1.22, 1.03, and 0.83 for the 5, 10, and 15 kg DM 100 -1 BW herbage allowances, respectively. The average daily weight gain (mean 0.42, 0.75, and 0.63 kg daily -1 ) and stocking rate (3.35, 1.87, and 1.26 animal unit ha -1 ) had a significant effect for the 5, 10, and 15 kg DM 100 -1 BW forage allowance, respectively. The herbage allowances were evaluated as being economically viable with a profit margin of 10.37, 23.65, and 14.43 % for the 5, 10, and 15 kg DM 100 -1 BW allowances, respectively. The greatest pasture response was found in the 5 kg DM 100 -1 BW allowance and was related to better nutritional values and morphological characteristics of the pasture and greater stoking rate and weight gain per area. The herbage allowance of 10 kg DM 100 -1 BW be applied to obtain higher animal performance and better economic viability of heifers in B. brizantha cv. Marandu pastures in a continuous grazing method that are receiving protein-energy supplementation.

The ideal regrowth age of forage plants and the use of fermentation stimulants additives may improve the fermentative characteristics and nutritive value of tropical grass silages. This study aimed to evaluate the effect of regrowth ages and the use of powdered molasses on nutritional characteristics of Zuri grass (Megathyrsus maximus) silages. A completely randomized design was used, in a 3x3 factorial scheme: three regrowth ages (65, 80, and 95 days) and three inclusion levels of powdered molasses of sugarcane (0, 20, and 40 g), with four replications. The chemical composition, fermentation parameters, in vitro digestibility, and in vitro degradation kinetics of the silages were evaluated. Greater DM contents were observed in silages with 95 days with 40 g of molasses. The 65 days of regrowth silages with 40 g of molasses had greater IVDMD compare to others treatments. However, lower pH values, N-NH3, DM losses, gas losses, and density were observed in silages with 95 days of regrowth with 40 g of molasses. It is recommended to cut the Zuri grass in the range of 80 to 95 days of regrowth with the addition of 40g/kg of molasses in powders for the production of silages.

Sugarcane is a source of roughage in animal feeding. It presents high production per unit of cultivated area, relatively easy cultivation and low cost of production per hectare, and better quality and a high dry matter (DM) yield in periods when forage is scarce. This study aimed to evaluate the effect of increasing levels of calcium hydroxide (Ca(OH)2) in sugarcane forage on chemical composition, in vitro digestibility values of DM, neutral detergent fibre (NDF) and acid detergent fibre (ADF), and kinetics of thermal decomposition processes of weight loss and heat flow. Sugarcane was collected close to the ground and 50-kg heaps of the fresh material were formed and mixed with four doses of Ca(OH)2 (0, 8, 16 and 24 g kg–1 sugarcane). Concentrations of NDF and ADF decreased linearly with increasing amount of Ca(OH)2, whereas concentration of hemicellulose increased linearly. In vitro digestibilities of DM, NDF and ADF were enhanced in a quadratic manner with increasing amounts of Ca(OH)2. The release of heat, measured by ΔH, increased linearly with increased Ca(OH)2 levels, likely due to enhanced digestibility of the fibre components. Weight loss decreased linearly between 272.2°C and 397.7°C with increased amounts of Ca(OH)2 added to sugarcane, likely due to changes in cellulose structure, which became denser and thermodynamically more stable than native cellulose following the alkaline treatment. Calcium hydroxide changed chemical composition and digestibility of the fibrous fraction of sugarcane, resulting in better nutritional value. The greatest release of heat and highest in vitro digestibility of fibre were observed when adding 15.2 g Ca(OH)2 kg–1 sugarcane; therefore, this dose is recommended to enhance the nutritive value of sugarcane as ruminant feed.

The ideal regrowth age of forage plants and the use of fermentation stimulants additives may improve the fermentative characteristics and nutritive value of tropical grass silages. This study aimed to evaluate the effect of regrowth ages and the use of powdered molasses on nutritional characteristics of Zuri grass (Megathyrsus maximus) silages. A completely randomized design was used, in a 3x3 factorial scheme: three regrowth ages (65, 80, and 95 days) and three inclusion levels of powdered molasses of sugarcane (0, 20, and 40 g), with four replications. The chemical composition, fermentation parameters, in vitro digestibility, and in vitro degradation kinetics of the silages were evaluated. Greater DM contents were observed in silages with 95 days with 40 g of molasses. The 65 days of regrowth silages with 40 g of molasses had greater IVDMD compare to others treatments. However, lower pH values, N-NH 3 , DM losses, gas losses, and density were observed in silages with 95 days of regrowth with 40 g of molasses. It is recommended to cut the Zuri grass in the range of 80 to 95 days of regrowth with the addition of 40g/kg of molasses in powders for the production of silages.

Even though marandu palisadegrass is widely used in Brazil, the consumption of this forage may cause photosensitization in ruminants due to the protodioscin. This study aimed to recommend a harvest cutting interval for haymaking that provides a better nutritional value and lower levels of protodioscin. The experimental treatments were four cutting intervals (21, 35, 49, and 63 days of regrowth period up to forage harvest). The experimental design was a completely randomized block design with 4 treatments and 4 replications. We assessed the forage production, chemical composition, in vitro digestibility, in vitro degradation kinetics, and protodioscin content. The forage accumulation rate did not differ with the increased cutting interval. The crude protein contents and in vitro digestibility of dry matter decreased linearly with the increased cutting interval in fresh and hay material. The greatest gas production in hay material was occurred in 21 d cutting interval, which was 26%, 14%, and 5% greater than cutting intervals of 63, 49, and 35 d, respectively. A linear increase was observed in protodioscin concentration in hay according to the cutting interval, which in the hay with 63 d cutting interval was 7%, 29%, and 43% greater than hays with cutting interval of 49, 35, and 21 d, respectively. In addition, protodioscin contents were lower in hay compared to fresh material. The haymaking process reduced protodioscin content in relation to forage before haymaking. Our results showed that the better condition to harvest marandu palisadegrass for hay was at 21 d. The better condition to develop a productive canopy is associated with better nutritive value and lower protodioscin content.