Fermentation characteristics and microbial growth promoted by diets including two‐phase olive cake in continuous fermenters

Abstract

Two-phase olive cake (2POC) is the by-product obtained from the so called 'two-phase' procedure to extract olive oil by mechanical methods. After the mechanical extraction the 2POC is dried and most of the remaining oil extracted by chemical means. The production of the crude by-product may reach more than 4 millions t/year in Spain (MAPA, 2003), most of it in areas (Southeast) with shortage of pastures and conventional feeds for ruminants. Six continuous fermenters, inoculated with ruminal liquor from wethers or goats, were fed lucerne hay (LH); LH plus a concentrate including dried two-phase olive cake (LHCO) and; diet LHCO added with polyethylene glycol (LHCOP). The highest pH values and ammonia N (NH(3)-N) output were found in fermenters fed diet LH (6.19 and 6.35 for pH, and 53.7 and 68.9 mg NH(3)N/day, respectively, in fermentes inoculated with rumen liquor from sheep and goats) without differences due to the inoculum origin. The digestibility of carbohydrates (CHO) was affected (p < 0.001) by inoculum (67.0 and 58.8%, respectively, for goats and wethers) the lowest values being for diet LHCO (53.2 and 57.0% with inoculum from wethers and goats, respectively). The main volatile fatty acid (VFA) was acetic acid with higher (p < 0.01) values in fermenters with inoculum from goats than from wethers (80.2 and 63.0 mmol/day respectively). The efficiency of bacterial protein synthesis (EBS) was not different (p > 0.05) with inoculum from wethers and goats [26.4 and 28.1 and 35.2 and 33.5 g bacterial N/kg digested CHO, respectively, obtained by using diamino pimelic acid (DAPA) and purine bases (PB) as microbial markers]. The lowest (p < 0.05) values were found in fermenters fed diets LHCOP and LH, estimated, respectively, from DAPA and PB (21.9 and 29.0 g bacterial N/kg digested CHO). The substitution of a part of lucerne hay by a concentrate including dried 2POC does not seem to cause important differences in efficiency of VFA production. Results concerning bacterial protein synthesis are not so clear since values estimated from DAPA and PB did not show similar trends. Neither inoculum origin nor PEG had important effects on fermentation characteristics. The DAPA could be an adequate marker in continuous fermenters, with comparative purposes, as protozoa are not present and, estimated protein synthesis values are similar to those obtained in vivo with similar diets using urinary excretion of PD (Yáñez Ruiz et al., 2004b). Further research is needed to state the optimal proportion of 2POC in practical diets for ruminants at both maintenance and production stages.

Ruminal fermentation, microbial growth and amino acid flow in single-flow continuous culture fermenters fed a diet containing olive leaves

“…None of these variables were affected (p = 0.135 to 0.980) by the inoculum source, and a significant diet × inoculum source was only detected for the molar proportion of acetate (p = 0.004) and the acetate/propionate ratio (p = 0.013). The lack of differences between the inoculum sources from goats and wethers is in accordance with the results from previous studies with single‐flow continuous‐culture fermenters fed diets of variable composition (Martín‐García et al., 2006; Moumen et al., 2008). In general, a lack of differences in the digestive capacity of sheep and goats has been shown when animals were fed good‐ or medium quality diets (Isac et al., 1994; Molina‐Alcaide et al., 2000), but interspecies differences have been reported with low quality diets.…”

“…The values of microbial growth efficiency ranged from 15.3 to 20.8 mg microbial N/g digested carbohydrate and were in the range of those previously obtained in fermenters fed diets based on AH or OL supplemented with different concentrates (Martín‐García et al., 2006; Molina‐Alcaide et al., 2008; Moumen et al., 2008). Rumen microbial yield and its efficiency depend on microbes growth rate and maintenance requirements, both varying with microbial species and environmental conditions, such as diet, pH, dilution rate and solids retention time (Dewhurst et al., 2000).…”

Use of tomato and cucumber waste fruits in goat diets: effects on rumen fermentation and microbial communities in batch and continuous cultures

“…Moreover, although the inclusion in the substrate of tomato and/or cucumber fruits reduced the proportion of isobutyrate and isovalerate, the concentrations of these VFA were over the level considered to be limiting for the growth of cellulolytic bacteria (Hume 1970). Values of efficiency of microbial growth were similar for all the substrates in Expt 2 and were in the range of those previously reported in continuous-culture fermenters for substrates including different agricultural wastes and agroindustrial by-products (Ariza et al 2001; Moumen et al 2008).…”

Comparison of bacterial pellets and microbial markers for the estimation of the microbial nitrogen and amino acids flows from single flow continuous culture fermenters fed diets containing two‐stage olive cake

“…In some small ruminant production systems, by‐products are traditionally used as an alternative source of nutrients during periods of scarce feed supplies. Several studies (Yáñez‐Ruiz et al., 2004; Moumen et al., 2008) have analysed the nutritive value of the two‐stage olive cake. This by‐product is obtained from the extraction of olive oil and contains condensed tannins which may decrease protein availability and microbial production (Makkar, 2003; Martín‐García et al., 2003).…”