This study aimed to investigate the associative effects caused by changes in the proportions of feed ingredients (forage-to-concentrate ratio) and the forage source in ruminant diets on in vitro gas production and fermentation parameters. The study consisted of two assays conducted in a completely randomized design with a 3 × 10 factorial arrangement consisting of three forages (pineapple crop waste silage [PS], corn silage [CS], and Tifton hay [TH]) associated with concentrate feed (C) (binary mixture) in 11 proportions, with triplicates of each combination. For the first assay, the asymptotic volume of gas did not show any difference among (p = 0.059) CS and PS (p = 0.464) and their proportions. We evaluated the associative effect among forages and their proportions and noticed there was an effect on gas production between the combination of forage and concentrate for the CS (p = 0.003) and PS (p = 0.003). In the second assay, volatile fatty acids (VFA) and ammonia nitrogen (p < 0.05) were affected by the forage source and concentrate inclusion. In conclusion, forages with a high content of soluble carbohydrates presented the lowest gas production, as well as higher concentrations of propionic acid and ammonia nitrogen. The associative effect on in vitro gas production was more pronounced in the first 12 h incubation. The different forage sources and the inclusion of concentrate change fermentation parameters.

This study aimed to empirically evaluate the adjustment quality of two stoichiometric models of methane production from diets that used different rumen fermentation modulators. We used the models proposed by Moss et al. (2000) and Blümmel et al. (1997). The data set consisted of 169 observations of in vitro methane production and volatile fatty acids (acetate, propionate, and butyrate) from dissertations, theses, and scientific articles. The model’s adequacy evaluation was only possible through combination of several statistical analyzes. The models were unable to predict the enteric methane precisely and accurately. Despite this, the model proposed by Moss et al. (2000) showed a better fit based on the mean bias (% of observed, MB), MEF, RMSEP, Cb and CCC measures compared to the model proposed by Blümmel et al. (1997). However, both models presented strong evidence against the general hypothesis H0: a = 0 & b = 1. Thus, the model proposed by MOSS et al. (2000) was more efficient, whereas the model by Blümmel et al. (1997) showed a better fit for diets with high availability of H2.

The study aimed to nutritionally evaluate the silage of pineapple crop waste in sheep feeding in different planes of nutrition (L). We used eight growing sheep and four male castrated adults, in individual metabolic cages distributed in a switch-back design with two treatments and three periods. The treatments were the different planes of nutrition: L = MEI⁄Mm, MEI⁄1.5Mm, and MEI⁄2.5Mm, in which L = MEI/Mm, MEI is the energy amount of the feed intake and Mm is the maintenance. [...] ABSTRACT The study aimed to nutritionally evaluate the silage of pineapple crop waste in sheep feeding in different planes of nutrition (L). We used eight growing sheep and four male castrated adults, in individual metabolic cages distributed in a switch-back design with two treatments and three periods. The treatments were the different planes of nutrition: L = MEI⁄Mm, MEI⁄1.5Mm, and MEI⁄2.5Mm, in which L = MEI/Mm, MEI is the energy amount of the feed intake and Mm is the maintenance.

The objective of this study was to evaluate the effect of the silo type with the use or not of additives on chemical composition, in vitro gas production, fermentative losses, aerobic stability, fermentative profile, and microbial population of the pearl millet silage. We used a randomized block design in a 2 × 3 factorial scheme, with two types of silos (plastic bags and PVC silos) and three additives ([CON] without additive; 50 g of ground corn [GC], and Lactobacillus plantarum and Propionibacterium acidipropionici, with five replicates per treatment. We evaluated the chemical analyses, in vitro gas production, losses, aerobic stability, pH, ammoniacal nitrogen, and microbial population of the silages. The use of GC in the ensiling process improved the chemical composition of the silages. The additives and the type of silo did not affect (p > 0.05) the gas production kinetics, ammoniacal nitrogen, and population of lactic acid bacteria and fungi. Thus, the use of ground corn improved the nutritional value of the pearl millet silage. In turn, the inoculant provided better aerobic stability for the pearl millet silage. The plastic bag silos without vacuum were not efficient in the ensiling process like the PVC silos, which resulted in low-quality silage.

Several studies on the kinetics of sugarcane’s fiber digestion have been published, but, to date, no study has evaluated the influence of sugarcane rind on the digestion of fresh sugarcane by ruminants. This study aimed to evaluate the effects of sugarcane components (rind and pith) on chemical composition, in vitro digestibility, metabolizable energy, and sugarcane quality. A randomized block design was used in a split-plot scheme with five sugarcane genotypes [plot] (RB068027, RB058046, RB987917, RB867515, and RB855536) and three sugarcane components [sub-plot] (rind, pith, and whole cane), Each treatment consisted of four replicates. The chemical composition, in vitro gas production, in vitro digestibility, metabolizable energy, and sugarcane quality were evaluated. No interaction between components and genotypes was observed for the variables analyzed herein. Although the rind had a higher crude protein content, it showed a large amount of insoluble crude protein. The rind had higher fibrous fractions, comprising 87.33 % of the indigestible fraction of the neutral detergent fiber (NDF). The sugarcane rind showed ~ 71.20 % more lignin than the pith tissue. Further, the rind decreased by 6.5 % in vitro dry matter digestibility compared to the whole sugarcane. The in vitro NDF digestibility of the rind was 18.38 % lower than the whole sugarcane. The RB068027 genotype showed the lowest sugarcane quality. Despite the higher content of potentially digestible neutral detergent fiber (pdNDF) in the rind, its high lignin content influences the quality of the final fibrous fractions of sugarcane and negatively impacts the nutritional value. The genotypes do not differ nutritionally, but RB855536 presented higher biomass and energy yields.

The objective of this work was to evaluate the supply, morphological and chemical composition of forage, performance and milk composition of crossbred cows managed in Megathyrsus maximus cv. Tanzania in intermittent grazing system with fixed and variable defoliation intervals according to the interception of 95% of photosynthetically active radiation by the canopy. The experimental design was a randomized complete block design with two treatments and two area replications. In each grazing cycle the supply, morphological composition, forage nutritive value, dry matter intake, milk production and composition were determined. The experimental area was 4.0 hectares, divided into two blocks of 2 hectares. Each block was subdivided into 22 pickets (11 for each treatment) totaling 44 pickets with an area of 909 m2 each. Significant differences (P < 0.05) were observed for leaf blade content, in vitro digestibility of dry matter and forage crude protein, dry matter intake, individual and area milk production and lactose content milk, being the highest values found in the pastures managed with variable defoliation interval. Thus, the defoliation interval defined by the 95% interception of the photosynthetically luminosity leads to higher leaf blade proportions in the forage canopy, resulting in higher individual milk yield and per unit area, but with a loss of protein and total solids contents of milk.