Chemical composition and fatty acid profile of BRS Capiaçu ensiled at different regrowth ages

Abstract

This study aimed to evaluate the chemical composition and fatty acid (FA) profile of chopped forage and silage of BRS Capiaçu elephant grass at four regrowth ages: 50, 70, 90 and 110 days. A randomized block design with five replications was used. The ensiling was carried out manually in experimental silos without wilting using no additives or bacterial inoculants. The results were analyzed using mixed models (P < 0.05). The model included treatment (regrowth age) as a fixed effect and block as a random effect. Linear and quadratic effects of the treatments were analyzed using orthogonal contrasts. There were linear increases in the dry matter (DM, g kg-1) and lignin (g kg-1 DM) contents and linear reductions in the in vitro DM digestibility (g kg-1) of chopped grass and silage as a function of regrowth age (P < 0.001). Quadratic effects (P ≤ 0.01) were observed for the chopped grass contents (g kg-1 DM) of crude protein (CP), ether extract (EE) and neutral detergent fiber (NDF) as a function of regrowth age. There were linear decreases (P < 0.0001) in the CP content (g kg-1 DM) and pH and linear increases (P < 0.001) in the EE and NDF contents (g kg-1 DM) in the silage as a function of regrowth age. There were linear decreases (P < 0.01) in the chopped grass contents and linear increases (P < 0.05) in the silage contents of total FAs, linoleic and α-linolenic acids (g kg-1 DM) asa function of regrowth age. BRS Capiaçu elephant grass must be harvested at up to 70 days of regrowth to obtain forage with good nutritional value and the highest levels of linoleic and α-linolenic acids (g kg-1 DM). To produce silages with adequate pH values and the highest levels of linoleic and α-linolenic acids (g kg-1 DM), BRS Capiaçu must be harvested between 90 and 110 days of regrowth.

Cutting Time and Regrowth Age Affect the Quality of Elephant Grass Silage

“…In Trial 1, silage of elephant grass harvested at 16 weeks showed lower IVDMD coefficients, probably because of the increase in the NDF and ADF levels that occurred with advancing RA. A similar result was observed by Lopes et al (2021), with the advancing RA of elephant grass cv. BRS Capiaç u.…”

“…A similar effect was observed in the present study since silages of elephant grass harvested at 16 weeks presented lower CP concentrations than silages of elephant grass harvested at 8 weeks. When evaluating chemical composition, before and after ensiling of elephant grass BRS Capiaç u at four regrowth ages (50, 70, 90, and 110 days), Lopes et al (2021) verified linear decreases in CP content with an increase in RA.…”

“…In a study of elephant grass silage cv. BRS Capiaç u harvested at 50-110 days of growth, Lopes et al (2021) also found a decrease in the CP content and an increase in the NDF content, as well as a decrease in silage pH.…”

Chemical composition and fatty acid profile of a seedpropagated elephant grass genotype, ensiled at different regrowth ages

“…Compared to forage, at all regrowth ages, expressive increases ranging from 65 -88% were observed in the silage EE contents (Table 2). These can be explained by the loss of water-soluble nutrients in the silo effluents or the fermentative products resulting in the concentration of EE in the silage DM (Baumont et al, 2011;Bochicchio et al, 2015) and corroborates the results of Bochicchio et al (2015) and Lopes et al (2021).…”

“…Total carbohydrates (TC) were calculated using the formula TC = 100 -(CP + EE + ash), and non-fibrous carbohydrates (NFC), which constitute fractions A and B1, were obtained using the formula NFC = TC -NDF ap . Fraction C was obtained by multiplying the lignin value by 2.4, and fraction B2 = NDF ap -fraction C. The second subsample was lyophilized (model L120, Liotop, Liobras, São Carlos, SP, Brazil), ground (1 mm), and analyzed for FA composition at the Laboratory of Chromatography of Embrapa Dairy Cattle (Juiz de Fora, MG) according to the procedures described by Lopes et al (2021).…”