Nutritional value of canola expellers produced "on farm" by cold extraction of oil used as bio fuel

General aim of this thesis was to study canola expellers (CE) extracted by cold pressing in a small plant (on farm) and to evaluate the validity to use this by-product in ruminant feeding. The thesis includes the results of four experimental contributes: the first one aimed to evaluate the stability of CE at different times and temperatures of storage in order to determine if the conditions usually found in the farms, especially during the hot season, can result in changes in fatty acids profile and in some oxidative parameters. Results found that under different temperatures (12, 24, and 36°C) and times of storage (10, 20, and 30 d), CE maintained a good oxidative stability, as evidenced by low peroxide values (< 10 mEq/kg fat) in all samples collected, by negative response for Kreis test and by low changes in fatty acids profile. From these results it could be hypothesized that the storage of these by-products did not change the characteristics of the lipid fraction. In the second contribute in vitro gas production (GP) values obtained from the incubation of CE, whole soybean seed (WSS) and soybean meal (SBM) were compared, incubating feed samples with two media containing N-rich buffer or N-free buffer, in order to compare the effect of the availability of feed as unique protein source. Results of the experiment showed that CE is an easily degradable protein source. In the first hours of incubation with limiting N availability, higher gas production was recorded compared to the two soybeans. On this basis, CE could be interesting in diets at low protein content, currently suggested in order to reduce nitrogen excretion. No toxic effects on the microbial yield were observed during the fermentation of the three different feeds. The third contribute compared four diets formulated for beef cattle, based on corn silage and containing WSS or CE as protein sources at two different inclusion levels, in order to obtain 15 and 11 % CP of DM in the diets. Diets were tested using Rusitec fermenter. Compared to WSS, CE provided greater NDF degradability (P < 0.01), produced less acetate and propionate (P < 0.001) but more butyrate and branched-chain VFA. The total VFA production was similar for the two protein sources. With regard to nitrogen balance, CE showed greater 15N enrichment in the non-ammonia N (P < 0.01) and nominally lower values of microbial N derived from ammonia compared to WSS (P = 0.06). At high inclusion level, the 15N enrichments for ammonia N, non-ammonia N and total bacteria N were also greater than observed at low inclusion levels (P < 0.001). In conclusion, the two feeds showed different fermentation patterns. The manipulation of dietary protein level seemed to lead primarily to a variation of bypass protein, without effects on the synthesis of microbial N. In the fourth contribute the same diets tested in Rusitec fermenter (third contribute) were evaluated using RF system (Ankom Technology, Macedon, NY, USA) in order to evaluate their gas production kinetics. Results showed that both NDFd and TDMd values were greater (P<0.05) for CE diets compared to WSS, confirming the results obtained with Rusitec and as expected were lower (P=0.04) for L compared to H diets. Compared to WSS, CE inclusion in the diets increased the rate of GP (P<0.05;) but did not affect the total amount of GP. The reduction of CP level in the diets from 15 to 11% decreased the rate of GP without effects on total GP. Ammonia content increased (P<0.01), as expected, with the level of dietary CP. In conclusion, when diets with low CE levels are used, the inclusion of rapeseed cake in replacement to soybean seeds could improve the rate of degradation during the first hours of fermentation. In general CE obtained by cold extraction on farm could be an interesting feed in ruminant feeding with economical and environmental benefits

Effect of Pressing and Combination of Three Storage Temperatures and Times on Chemical Composition and Fatty Acid Profile of Canola Expellers

This experiment investigated the effects of combinations of three temperatures and storage times on chemical composition, fatty acid profile, and oxidative stability of canola expellers obtained from the cold-pressing extraction of oil. Canola seeds were single-crushed at moderate temperatures (60°C) during 3 pressing sessions. Nine samples (100±1 g) of each session were collected, inserted into sealed bags, stored at three temperatures (12, 24, 36°C) over 3 periods of time (10, 20, 30 d). Then, samples (100±1 g) of canola seeds collected before each pressing session and canola expellers collected before and after each storage time were analyzed for chemical composition, fatty acid profile, peroxide number and Kreis test. Before storage, the fatty acid profile of canola seeds and expellers differed significantly, except for myristic (P=0.18), palmitic (P=0.57), oleic (P=0.07), and α-linolenic acids (P=0.45). Compared to canola seeds, expellers showed greater content of saturated, poly-unsaturated, and n-6 fatty acids (P<0.01), but a lower content of mono-unsaturated fatty acids (P<0.01). Peroxide values were definitely (P<0.01) greater for expellers and averaged 4.22 and 4.11 mEq/kg fat before and after storage, respectively. The Kreis test was negative for all samples. Under different temperatures and times of storage, canola expellers showed to maintain a good oxidative stability, as highlighted by low peroxide values (<10 mEq/kg fat) and negative response for Kreis test. Canola expellers obtained by on-farm cold extraction, despite great oil residual (from 17 to 19% ether extracts on dry matter basis), can be stored at farm without significant chemical and nutritional changes

Associative effects of poor-quality forages combined with food industry byproducts determined in vitro with an automated gas-production system

This experiment aimed to investigate the associative effects among two low-quality forages (crown daisy, milk thistle) and three agro-industrial byproducts (apple pomace, citrus pulp, tomato peel), by means of an automated gas production (GP) system. All feeds were incubated alone or as 50 : 50 mixtures of each forage with each byproduct. Samples (0.5 g) of single feeds or mixtures were incubated for 96 h, in three replicates in individual bottles (310 mL), with 75 mL of buffered rumen fluid. Bottles were vented by an open-close valve when the internal pressure reached 3.4 kPa. The metabolisable energy content of single feeds and mixtures was computed from GP at 24 h and feed chemical composition. Feed substrates were ranked for GP in the following way: byproducts, mixtures, and forages. The two forages did not differ for GP and metabolisable energy content, although differences were observed among byproducts and among mixtures. Both forages interacted positively with apple pomace from 6 h (P < 0.001) to 24 h (P = 0.029) of incubation and with citrus pulp at 12 h (P = 0.005) and 24 h (P = 0.012), whereas no associative effects were detected when forages were incubated with tomato peels. Results suggest that in vitro fermentability of low-quality forages could be efficiently improved by combining these two forages with apple pomace or citrus pulp. These findings are relevant, because the use of low-quality forages and byproducts in ruminant feeding is considered important for improving the environmental and economic sustainability of forage systems in arid and semi-arid areas