This study was conducted to investigate the nutritive value of avocado and mango fruit wastes, and to assess the possibility of preserving the wastes into multi-nutrient blocks (MB). Both peels and a pulp:peels (PP) mixture of each fruit were analyzed for chemical composition and in vitro fermentation with goats’ ruminal fluid. Wastes had low-dry matter (DM) content (<250 g/kg), with those from mango having high non-structural carbohydrates content (>800 g/kg DM) and those from avocado high fat levels (>580 g/kg DM). Mango wastes were fermented at a greater extent and faster rate than avocado ones. The PP mixture of each fruit was included into multi-nutrient blocks (MB) formulated to have similar chemical composition. There were only subtle differences in the fermentation of MB including wastes from either avocado or mango, but fermentation of avocado-MB resulted in significantly (p ≤ 0.032) greater acetate and lower propionate proportions than mango-MB. Including the PP mixture in the formulation of MB for goats feeding is a feasible option to reduce the environmental impact of avocado and mango fruit wastes, but studies on the acceptance of the MB by goats and their stability over long-time storage periods are needed.

The aim of the present work was to investigate the potential of Porphyra sp. as an alternative source of protein to soybean meal in diets for sheep. Our experimental treatments included a control diet (CON) based on grass silage and crushed oats and three diets containing protein supplements, clover silage (CLO), soybean meal (SOY) or Porphyra sp. (POR) to increase dietary crude protein concentrations. We studied its effects on rumen fermentation, growth rate and methane emissions. Ruminal fermentation characteristics, kinetics of gas production and methane production were studied in vitro by using batch cultures inoculated with rumen inoculum from sheep. There were no differences among diets in total volatile fatty acids (VFA) production or in the VFA profile in vitro. Across treatments, we measured no differences in methane production either in vitro or in vivo, and we saw no noticeable antimethanogenic effect of Porphyra sp. The present in vivo trial with lambs showed no differences in average daily weight gain when fed diets including Porphyra sp. or soybean meal diets (250 and 254 g/d, respectively). We conclude that Porphyra sp. has a protein value similar to high-quality protein sources like soybean meal.

An important limitation of continuous-culture fermenters is their inability of maintaining microbial populations similar to those observed in the rumen, especially protozoa numbers, which usually decrease markedly or even disappear. Two approaches (a polyurethane-sponge (SP) and a filter system (FIL) for additionally retaining protozoa were tested in continuous culture system already designed to retain protozoa (Muetzel et al., 2009), and their effects on microbial populations, fermentation parameters and microbial biomass were assessed. Two 14-day incubation runs were carried out with 6 fermenters, and in each run two fermenters were randomly assigned to each of the experimental treatments (control, SP and FIL). Total protozoa numbers assessed by microscopic counting were 1.7 and 2.1 times greater in SP and FIL fermenters than in control ones on day 14, although differences did not reach the significance level (P = 0.855). Protozoal DNA concentration on day 14 were 1.6 and 1.4 times greater in SP and FIL fermenters, respectively, than in control ones, but differences were not significant (P = 0.524). Results from protozoal DNA concentrations determined in each fermenter on the different sampling days (n= 48) were positively correlated (P < 0.001) with the numbers of total (r = 0.826), entodiniomorphid (r =0.824) and holotrich (r = 0.675) protozoa determined by microscopic counting, indicating that both methods are valid to assess protozoa populations. The proportion of holotrich in FILfermenters was relatively constant over the incubation period (ranging from 10.5 to 13.3% of total protozoa), but decreased with time in control (from 10.9% at day 2 to 6.7% at day 14) and SP (from 10.9 to 6.9%) fermenters. Neither the bacterial DNA concentration nor the relative abundance of fungal and archaeal DNA were influenced by any of the modifications tested, but values changed over the sampling period (days 10-14). Bacterial DNA concentration increased (P < 0.001) from day 10 to 14 in all fermenters, whereas the relative abundance of fungal and archaeal DNA decreased (P < 0.001). The tested modifications did not affect (P > 0.05) fermentation parameters, which reached a steady-state after 6 days of incubation. Values of microbial biomass determined using purine bases as a microbial marker were significantly correlated with the amount of bacterial plus protozoal DNA (r = 0.794; P = 0.002; n =12) in each Abbreviations: ADFom, acid detergent fiber expressed exclusive of residual ash; aNDFom, neutral detergent fiber with heat-stable amylase and expressed exclusive of residual ash; CON, control treatment (fermenters without modification); CP, crude protein; EE, ether extract; FIL, fermenters provided with a filter system; PCA, principal component analysis; PB, purine bases; SP, fermenters provided with a polyurethane-sponge; VFA, volatile fatty acids fermenter. In conclusion, the two tested modifications increased the protozoa numbers in continuous-culture fermenters, and the FIL allowed maintaining a proportion of holotrich pr...