Brewer's Grain Research Articles

Physico-chemical characteristics and degradation rate of soluble protein obtained from the washout fraction of feeds

The (water)-soluble fraction of feeds is often assumed to be completely and immediately degraded in the rumen. The objective of this study was to separate the washout fraction (fraction A) obtained usually by difference after submitting the nylon bags to the machine-washing program, to investigate the nature and the degradation of the soluble crude protein in the washout fraction. The washout fraction obtained in vitro (filtrate) of 10 feeds was collected in water using nylon mesh as a filter. The feeds used in the study were: two grass silages, soybean meal, three corn gluten feeds, lupine meal, rapeseed meal, wet brewers grain silage and corn gluten feed silage. Average N losses during filtration and from machine-washed nylon bags ranged from 15% (rape seed meal) to 74% (grass silage) and were not different between procedures. N recovered in the filtrate ranged from 12% (soybean meal) to 60% (corn gluten feed silage) of sample N. The three fractions obtained from the filtrate were: soluble protein (TP), non-protein N (NPN) and fine particles (NS). The NS fraction was obtained after centrifugation of the filtrate and comprised 0% to 87% of N in the filtrate. Soluble protein (TP) in the supernatant was obtained after precipitation with trichloroacetic acid and N in the remaining supernatant was defined as non-protein N (NPN). Significant amounts of TP were found in soybean meal (58%), lupine meal (30%) and rapeseed meal (27%) as percent of total N in the filtrate. NPN ranged from 13% to 100% of N in the filtrate. The in vitro incubation of the protein N (NS + TP) showed that all fractions were not completely degraded, suggesting a potential participation as escape protein. Fine particles in the filtrate have similar degradation rates as the residue left in the filter. It is concluded that the washout fraction consisted of different crude protein fractions that were not always completely and immediately degraded in the rumen.

Prevalence of and Risk Factors for Escherichia coli O157 in Market-Ready Beef Cattle from 12 U.S. Feedlots

Determination of Escherichia coli O157 prevalence immediately prior to shipment and harvest is an important facet of the ecology of this organism, which requires further elucidation. As part of a larger study to measure the effects of within-pen prevalence of E. coli O157 on subsequent carcass contamination, fecal samples from 15 pens of cattle in each of 12 different feedlots in three states (Colorado, Nebraska, and Montana) were collected from June through September 2002. Thirty fresh fecal samples were collected from each pen floor within 36 h of shipment to slaughter. Fecal samples underwent standard enrichment, immunomagnetic separation, and isolation procedures for E. coli O157. Multivariable logistic regression was used to determine which factors best predicted pen-level positive culture results, and to estimate the magnitude of association between each factor and the outcome, while adjusting for other factors in the model. Thirteen (86.7%) of the 15 pens had at least one positive sample, and the within-pen prevalence of E. coli O157 in positive pens ranged from 3.3% to 77.8%. The odds of E. coli O157 positive fecal samples from cattle fed brewers grains were six times that for cattle not fed brewers grains. The odds of E. coli O157 positive fecal samples from pens of cattle from Central Nebraska was nine times that for pens of cattle from Eastern Colorado. These data demonstrate that the presence of E. coli O157 in fecal samples from finished feedlot cattle is associated with feeding of brewers grain and geographic location. Additional studies to further characterize geographic distribution of E. coli O157 and to investigate pen-level intervention strategies should be conducted.

Comparison of voluntary feed intake, rumen passage and degradation kinetics between crossbred Brahmam cattle (Bos indicus) and swamp buffaloes (Bubalus bubalis) fed a fattening diet based on corn silage

ABSTRACTThree crossbred tropical cattle and three crossbred buffaloes, fitted with rumen cannulas, were used to investigate the differences in feed intake, digestibility and parameters with rumen degradation kinetics between cattle and buffalo fed a fattening diet in the Philippines. The animals were fed a diet consisting of 50% corn silage (CS), 30% brewer's grain (BG) and 20% concentrate mixture (CM) on a dry matter (DM) basis, at a level of 3% bodyweight (BW) as DM. Total DM intake (DMI) and rumen fill were greater (P < 0.05) for buffaloes than for cattle, but significant differences were not detected between the animal species when those were expressed as percentage of BW. The DMI per metabolic body size for BG and CM were greater for buffaloes than for cattle (P < 0.05), whereas that of CS did not differ between the species (P > 0.05). The weight proportion of consumed feedstuffs differed between cattle and buffaloes (P < 0.05), although nutrient intake per total DMI did not differ significantly (P > 0.05) between the animal species. Nutrients digestibility was higher (P < 0.05) for buffaloes than for cattle. Ruminal passage rate constant of feed particles and rumen fluid did not differ (P > 0.05) between the animal species. Higher DM degradation rate constant and effective degradability with CS were prominent for buffaloes than for cattle (P < 0.05). Degradation parameters did not differ (P > 0.05) between cattle and buffaloes, neither with BG nor CM. The results indicate that the greater digestibility with DM and energy for buffaloes are ascribable to greater effective degradability of CS fedad libitumlevel.

Microbial Counts, Fermentation Products, and Aerobic Stability of Whole Crop Corn and a Total Mixed Ration Ensiled With and Without Inoculation of Lactobacillus casei or Lactobacillus buchneri

Whole crop corn (DM 29.2%) and a total mixed ration (TMR, DM 56.8%) containing wet brewers grains, alfalfa hay, dried beet pulp, cracked corn, soybean meal, and molasses at a ratio of 5:1:1:1:1:1 on fresh weight basis, were ensiled with and without Lactobacillus casei or Lactobacillus buchneri in laboratory silos. The effects of inoculation on microbial counts, fermentation products, and aerobic stability were determined after 10 and 60 d. Untreated corn silage was well preserved with high lactic acid content, whereas large numbers of remaining yeasts resulted in low stability on exposure to air. Inoculation with L. casei suppressed heterolactic fermentation, but no improvements were found in aerobic stability. The addition of L. buchneri markedly enhanced the aerobic stability, while not affecting the DM loss and NH3-N production. Large amounts of ethanol were found when the TMR was ensiled, and the content of ethanol overwhelmed that of lactic acid in untreated silage. This fermentation was related to high yeast populations and accounted for a large loss of DM found in the initial 10 d. The ethanol production decreased when inoculated with L. casei and L. buchneri, but the effects diminished at 60 d of ensiling. Inoculation with L. buchneri lowered the yeasts in TMR silage from the beginning of storage; however, the populations decreased to undetectable levels when stored for 60 d, regardless of inoculation. No heating was observed in TMR silage during aerobic deterioration test for 7 d. This stability was achieved even when a high population of yeasts remained and was not affected by either inoculation or ensiling period. The results indicate that inoculation with L. buchneri can inhibit yeast growth and improve aerobic stability of corn and TMR silage; however, high stability of TMR silage can be obtained even when no treatments were made and high population (>105 cfu/g) of yeasts were detected.

Arabinoxylan and mono- and dimeric ferulic acid release from brewer's grain and wheat bran by feruloyl esterases and glycosyl hydrolases from Humicola insolens.

An enzyme preparation from the thermophilic fungus Humicola insolens, Ultraflo L, was able to solubilise more than half of the biomass of brewer's grain and wheat bran, two agro-industrial co-products. While almost all of the ferulic acid was released in the free form, the majority of diferulates were released still attached to soluble feruloylated oligosaccharides, except for the 8,5' benzofuran form, which remained mostly in the residue. H. insolens also produced an esterase capable of releasing over 50% of p-coumaric acid present in wheat bran, but only 9% from the brewer's grain. The polysaccharide content in the residues after enzyme treatment comprised mostly cellulose and arabinoxylan, which suggests that part of the arabinoxylan in these residues is inaccessible to the xylanases of H. insolens. Differences in the solubilised arabinose-to-xylose ratio coupled to high free ferulate release suggest that the structure of feruloylated arabinoxylan in barley and wheat may differ.

Roughage Energy and Degradability Estimation with Aspergillus oryzae Inclusion Using Daisy® In vitro Fermentation

The aim of this study was to predict the energy value and dynamic degradation of roughage in Taiwan using the Daisy  in vitro fermentation method to provide information on one of the very important nutrients for ration formulation. The second objective was to study the effects of Aspergillus oryzae (AFE) inclusion on nutrient utilization. Three ruminal fistulated dry dairy cows were used for rumen fluid and fifteen conventional forages used in dairy cattle were collected around this island. The degradability of these feedstuffs with and without AFE (Amaferm  ) treatment was measured using the Daisy  in vitro method. The roughage energy values, including TDN and NEL, were calculated according to Robinson (2000). Results from the 30 h in vitro neutral detergent fiber (NDF) degradability and predicted energy evaluations showed that alfalfa (among the forages) contained the highest degradability and energy values, Bermuda straw having the lowest. Peanut vines and corn silage contained higher energy values and the lowest value found in Pangola and Napier grasses among the locally produced forages. Pangola and Napier grasses had lower values than most imported forages except Bermuda straw. Among the by-products, wheat middling contained the highest NDF degradability, while rice bran contained the richest energy value due to its high oil content. From the dynamic dry matter (DM), organic matter (OM), acid detergent fiber (ADF) and neutral detergent fiber (NDF) degradation, corn silage contained the highest effective degradation among the local forages; wheat middling (among the by-products) degraded the fastest in DM, OM, ADF and NDF and showed the highest effective degradability. AFE inclusion was inconsistent among the forages. Alfalfa hay showed significantly increased 30 h NDF degradability and energy values, Pangola hay, Napier grass and brewer's grains showed decreased degradability and energy values. AFE inclusion increased the DM, OM and NDF degradation rate in most forage, but only increased the DM degradation rate in sorghum distiller's grains, the OM degradation rate in bean curd pomace and the NDF and ADF degradation rates in soy pomace (among the by-products). (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 1 : 53-62)

Pretreatment and Hydrolysis of Brewer's Spent Grains

AbstractBrewer's spent grains (BSG), the voluminous residue after mashing, contains on dry weight basis about 40–50 % polysaccharides. For the recovery of soluble carbohydrates from BSG different physical, thermal and enzymatic treatments were used to solubilize the polysaccharides in BSG. Heating by microwave radiation to 160 °C in the presence of 0.1 M HCl released 35 % of the material in the form of reducing sugar, indicating that about 80 % of the polysaccharides were hydrolyzed. Nevertheless, 0.1 M acetic acid will even solubilize 30 % of the material as oligosaccharides on a prolonged incubation when pretreating the spent grains by extrusion cooking. A combination of the enzymes Ceremix Plus MG and CelluPract AL 70 achieved an almost 25 % release of saccharides after 4 hrs of incubation at 50 °C. A combination of extrusion cooking and enzymatic hydrolysis seems to be a very promising procedure.

The necessity of a surplus in the nitrogen balance in the rumen of cows having high milk production

The amount of crude protein entering the small intestine (nXP) and the nitrogen balance in the rumen (RNB) are the two components of the German protein evaluation system. Although there is no scientific evidence, feeding strategies for the practice imply an excess in RNB, particularly in diets for high-yielding cows. This study was undertaken to investigate whether cows benefit from an excess in RNB under conditions of sufficient nXP supply. Three rations were used equal in energy (7.2 MJ net energy for lactation per kilogram dry matter; DM) and nXP (173 g/kg DM) and mainly based on silages from maize, grass, and brewer's grains as well as ground barley and solvent extracted meals from rapeseed and soybeans. Three rations were calculated to allow for an RNB of either 0 or 50 g/day. RNB was adjusted by either a supplementation of urea or a change in the proportions of oilseed meals. The intended levels of energy, nXP and RNB in the diets were confirmed under consideration of separate digestibility measurements with wether sheep and a chemical fractionation of dietary crude protein. The rations were offered as total mixed rations. At least 35 cows between days 21 and 98 of lactation were used per treatment. Cows were milked three times daily and had continuous access to feed and water. Feed intake was measured continuously and for each cow individually by a feeder system through which the rations were offered. The average values for the three treatments ranged between 20.1 and 21.7 kg/day for DM intake, 43.0 and 44.0 kg/day for milk yield, and 1.39 and 1.42 kg/day for milk protein yield. No significant treatment effect was detected in any of the monitored criteria. Cows were in a negative energy budget as indicated by a loss in backfat thickness, similar for all treatments. Under inclusion of literature data it is concluded that under conditions of a sufficient nXP supply, dairy cows do not need an excess in RNB in total mixed rations, even at very high levels of milk protein yield.

Partial and total replacement of fish meal with soybean meal and brewer's grains with yeast in practical diets for Australian red claw crayfish Cherax quadricarinatus

Three feeding studies were conducted to evaluate the effects of total replacement of fish meal (FM) with a combination of soybean meal (SBM) and brewer's grains with yeast (BGY) in diets for two separate strains of juvenile Australian red claw crayfish. In Experiment 1, three practical diets were formulated to be isonitrogenous (40% protein) and isocaloric (4.0 kcal available energy/g diet) and contained either 25%, 10%, or 0% fish meal. Variable percentages of SBM (35%, 46.8%, and 79.8%, respectively) and BGY-35 (0%, 30%, and 5%, respectively) replaced the fish meal. In Experiments 2 and 3, four practical diets were formulated to be isonitrogenous (40% protein) and isocaloric (4 kcal available energy/g diet) containing 24% or 0% fish meal. Diet 1 contained 24% fish meal, 23% SBM, and 0% BGY-35. A variable percentage of SBM (56.75%, 47.75%, and 40.75%, respectively) and BGY-35 (10%, 20%, and 30%, respectively) replaced the fish meal in the remaining three diets. In Experiment 1, after 8 weeks, juvenile red claw fed all three diets had no significant difference ( P>0.05) in final weight, percentage weight gain, or survival, which averaged 7.90 g, 3848%, and 83%, respectively. In Experiment 2, after 8 weeks, juveniles fed all four diets had no significant difference in final weight, percentage weight gain, or specific growth rate which averaged 11.46 g, 977%, and 3.08%/day, respectively. Percentage survival was not significantly different among treatments and averaged 79%. In Experiment 3, after 8 weeks, juvenile red claw fed all four diets had no significant difference in final weight, percentage weight gain, or specific growth rate which averaged 16.22 g, 457%, and 2.34%/day, respectively. Percentage survival was not significantly different among treatments and averaged 98%. These results indicate that fish meal and shrimp meal can be totally replaced with soybean meal and BGY in diets for juvenile red claw crayfish. This may allow for less expensive diets by red claw producers, which may increase profitability.

Effect of Dietary Carbohydrate Composition and Availability on Utilization of Ruminal Ammonia Nitrogen for Milk Protein Synthesis in Dairy Cows

A trial with four ruminally and duodenally cannulated, late-lactation dairy cows was conducted to investigate the effect of dietary carbohydrate (CHO) composition and availability on ruminal ammonia N utilization and transfer into milk protein. Two diets were fed at 8-h intervals in a crossover design. The diets differed in CHO composition: the ruminally fermentable nonstructural carbohydrates (RFSS) diet (barley and molasses) contained a larger proportion of ruminally available CHO in the nonstructural carbohydrate fractions and the ruminally fermentable fiber (RFNDF) diet (corn, beet pulp, and brewer's grains) contained a larger proportion of CHO in ruminally available fiber. Nitrogen-15 was used to label ruminal ammonia N and consequently microbial and milk N. Fermentation acids, enzyme activities, and microbial protein production in the rumen were not affected by diet. Ruminal ammonia concentration was lowered by RFNDF. Ruminal and total tract digestibility of nutrients did not differ between diets except that apparent ruminal degradability of crude protein was lower for RFNDF compared with RFSS. Partitioning of N losses between urine and feces was also not affected by diet. Milk yield and fat and protein content were not affected by treatment. Average concentration of milk urea N was lower for RFNDF than for RFSS. Proportion of milk protein N originating from ruminal microbial N (based on the areas under the 15N-enrichment curves) was higher for RFNDF than for RFSS. Cumulative recovery of 15N in milk protein was 13% higher for RFNDF than for RFSS indicating enhanced transfer of 15N-ammonia into milk protein with the former diet. The results suggested that, compared to diets containing higher levels of ruminally fermentable starch, diets providing higher concentration of ruminally fermentable fiber may enhance transfer of ruminal ammonia and microbial N into milk protein.

Impact of mammalian enzyme pretreatment on the fermentability of carbohydrate‐rich feedstuffs

AbstractSeveral carbohydrate‐rich substrates (spent brewer's grains, potato peel, potato starch, wheat bran, sugarbeet pulp and a maize‐based standard diet for pigs) were pretreated with digestive enzymes, and the in vitro fermentability of these treated substrates and their untreated counterparts was assessed using the cumulative gas production technique. A comparison was also made between the enzyme‐treated (ET) and untreated (UT) standard diet for pigs, and chyme which originated from pigs fed that diet, to determine whether the enzyme treatment resulted in material with similar fermentability to that reaching the large intestine in vivo. The enzyme pretreatment was performed according to a modified in vitro method of Babinszky et al (J Sci Food Agric 50:173–178 (1990)). Generally, it was shown that the fermentabilities of the ET and UT substrates were different. There was also a significant difference between the fermentation characteristics of the ET diet and chyme. Chyme produced less gas (P < 0.05), and the time at which half of the gas had been produced (C) occurred later (P < 0.05). The maximum rate of fermentation (R M) was slower for chyme (P < 0.05). Fermentation of chyme led to more ammonia (P < 0.05) and a tendency to more volatile fatty acids at the end of fermentation. These differences in fermentability of the ET diet and chyme (from pigs fed the same diet) may be the result of differences which relate purely to the action of the enzymes chosen to work in vitro, compared with those which are actually present in vivo. However, the results also suggest that it is not only enzymatic digestion which is occurring in the small intestine. This is an important consideration when using ileal techniques to determine digestibility of feedstuffs.© 2003 Society of Chemical Industry

Supplementation of Dry Brewer's Grain to Lower Quality Forage Diet for Growing Lambs in Southeast Nigeria

Twenty yearling lambs of Southeast Nigeria dwarf, liveweight (18±1.9 kg) were grouped into 5 treatments. Dry brewer's grain was substituted for maize offal in the experiment diets namely A to E at 0%, 15%, 30%, 45% and 60% respectively, as supplement to low quality, dry season cassava leaf top and Andropogan gayanus hay at 1:1 ratio that lasted for 56 days. After which 5 of the lambs (average bodyweight=24.3±1.5 kg) were transferred to metabolism crates to determine the digestibility and nitrogen/protein balance studies. While the mean group intakes were (945.9, 996.1, 1,040.5, 1,148.5 and 1,037.7 g conc. DM/day), the growth rates were (115.1, 124.1, 152.5, 168.5 and 123.1 g liveweight gain/day), respectively. There was a recorded decline in both intake (p>0.05) and growth rate (p 0.05) together with the organic matter intake. The urine nitrogen output was also significant (p>0.05). The work further revealed that, at a certain critical level of intake, dry brewer's grain is able to support growth rates measurable to or better than those noted when feeding maize offal to lambs, and went on to prove dry brewer's grain as an attractive supplementary feed for the drier months of the year, in the Southeast of Nigeria. (Asian- Aust. J. Anim. Sci. 2003. Vol 16, No. 3 : 384-388)

Chemical composition and rumen degradation of diet combinations of cottonseed cake, dried brewer's grains and <i>Lablab purpureus</i> hay incubated in the rumen of fistulated N'dama steers in South-western Nigeria

The chemical composition and dry matter (DM) and nitrogen (N) degradation characteristics of four diet combinations at four total digestible nutrients (TDN) levels of cottonseed cake (CSC), dried brewer's grains (DBG) and Lablab purpureus hay (LL) which were fed to ruminants in the humid zone of Ibadan, South-west Nigeria, were evaluated. The TDN levels used were 3.5, 4.5, 5.5 and 6.5 kg TDN. The CSC and DBG used are agro-industrial by-products which are used in feeding livestock while the LL is a leguminous plant which is not used much as human feed but is usually grown as forage legume for animal feeding. The completely randomized design with four treatments and three replicates was used. The experiment was carried out in Ibadan, South-western Nigeria during the wet season (June to July). The diets were high in crude protein contents so that they had high nutritional potential for ruminants feeding and productivity. The potential degradability (PD) of dry matter (DM) values ranged from 75.24 to 79.47 g/ 100g DM, while that for the nitrogen (N) degradability ranged between 88.36 and 94.30 g/100g N. The soluble fraction a value of DM degradation and the crude fibre (CF) content of the chemical composition of the diets were significantly correlated (r= 0.644; P= 0.007). The potential degradability (PD) values for both the DM and N degradabilities were not significantly (P>0.05) different among the four treatment diets combinations. Keywords: Chemical composition, degradation, N'dama steers, cotton seed cake, dried brewer's grainsLablab purpureus

Tropical fibre sources for pigs—digestibility, digesta retention and estimation of fibre digestibility in vitro

The digestibility of high-fibre diets and digesta passage was measured in growing pigs and attempts were made to predict the in vivo digestibility from in vitro data. In Experiment 1, six diets were formulated to measure digestibility using low-fibre cassava starch, fish meal and soya bean meal in combination with six locally available fibre sources. Four green plants: banana sheaths ( Musa paradisiaca), duckweed ( Lemna minor), sweet potato vines ( Ipomoea batatas) and water spinach ( Ipomoea aquatica) were used for the BS, DW, SPV and WS diets, respectively. In addition two by-products, copra meal (CM) and tofu residues (TR), were used for the CM and TR diets, respectively. Digesta retention of solids was measured using chromium mordanted Para grass ( Brachiaria mutica) fibre and Co–EDTA was used for the retention of liquid. In Experiment 2, the digestibility of diets based on the fibre sources: brewer’s grains (BG), copra meal, cassava residues (CR), whole ground rice (WGR), coarse rice bran (RB) and tofu residues was measured in growing crossbred Baxuyen pigs. These fibre sources replaced 30% of a basal diet consisting of mainly maize, rice bran, soya bean meal and fish meal. The diets from Experiments 1 and 2 were also used to measure in vitro neutral detergent fibre (NDF) degradation, using faecal inocula taken from pigs fed on the same diets. In Experiment 1, the coefficient of total tract apparent digestibility (CTTAD) organic matter (OM), crude protein (CP), and neutral detergent fibre values of all, except for the BS diet, were similar and ranged from 0.82 to 0.84, 0.65 to 0.76 and 0.69 to 0.72, respectively. CTTAD for OM, CP and NDF of the BS diet were, however, significantly lower and 0.72, 0.60 and 0.32, respectively. Solids and liquid mean retention times (MRT) for the BS diet were 22.2 and 22.6 h and for the other diets, MRT ranges were 32.9–38.9 and 29.5–36.9 h, respectively, and were similar for the two markers ( P=0.31). In Experiment 2, CTTAD for OM of the WGR and RB diets were 0.73–0.77 and for NDF 0.57–0.64. These data were lower than those for the other diets ( P=0.01), which were similar and were 0.82–0.90 and 0.70–0.79, respectively. Crude protein CTTAD for the BAS diet (0.87) was significantly higher than that of the TR (0.73) and WGR (0.75) diets ( P<0.01). There was a high correlation between the NDF digestibility in vitro at 36 h and in vivo in Experiment 1 ( r 2=0.92, R.S.D.=0.035). The results indicate that the green plants and high-fibre by-products had relatively high CTTAD of OM, CP and NDF and could be reasonable feed resources for pigs, even though intake will restrict the levels of inclusion from 200 to 350 g kg −1 of the diet. However, lignin and silica limited the utilisation of coarse rice bran, and a short retention time and the high-fibre and tannin contents reduced the digestibility of the banana sheaths. In vitro NDF degradation seemed to be a reliable predictor of in vivo NDF digestibility.

Lactation Performance by Dairy Cows Fed Wet Brewers Grains or Whole Cottonseed to Replace Forage ,

Holstein cows starting at wk 8 of lactation were used to evaluate lactation performance when wet brewers grains, whole linted cottonseed, or starch-coated whole linted cottonseed (Easiflo™) were substituted for forage. The wet brewers grains were added to diets to decrease forage neutral detergent fiber from 21% incrementally down to 15% while simultaneously decreasing nonfiber carbohydrate concentration from 40.3% down to about 33.8%. The cottonseed treatments all had similar concentrations of forage neutral detergent fiber (15%) and nonfiber carbohydrates (33.1 and 36.0%). Dry matter intake and milk production were similar across treatments. Milk fat percentage was decreased for Easiflo versus whole linted cottonseeds, but no other responses were detected. The current National Research Council (NRC) energy model was evaluated using individual cow data that were averaged over the entire 16-wk treatment period. For treatment means, the output of energy averaged 99% of the net energy of lactation intake, indicating very good corroboration of the model to account for energy usage for a group of cows. However, the ability to predict energy usage for individual cows was less accurate based on the comparison of residuals of observed and predicted body weight change regressed against predicted body weight change, apparently because of compounding of random errors in this prediction, which was alleviated over a larger number of observations. These results also corroborate current NRC guidelines for minimum forage neutral detergent fiber concentrations for lactating cows past the calving transition period.

Seasonal variation in milk conjugated linoleic acid and Δ 9-desaturase activity in dairy cows

The objective of this work was to study changes in the fatty acid profile of cows’ milk throughout the year with particular emphasis on cis-9, trans-11 conjugated linoleic acid (CLA), a proven anticarcinogen, found predominantly in milk and meat from ruminants. During the winter months, a total mixed ration of grass and maize silages, brewers grains, cereals, soya and dairy concentrates was fed. Through the summer months, fresh grass was fed, with increasing levels of buffer feeding given as the summer progressed. The CLA content of milk in May, June and July was significantly higher ( P<0.05) than all other months, averaging 1.50 g CLA/100 g FAME compared with a mean of 0.77 g/100 g for the other months. Δ 9-Desaturase activity was also greater in the summer. Milk fat produced during the summer contained significantly ( P<0.05) greater amounts of short-chain fatty acids at the expense of medium-chain fatty acids indicating that fresh grass may alter the pattern of fatty acids produced de novo in the mammary gland. Results suggest that fresh grass promotes the synthesis of CLA in the dairy cow through an increase in Δ 9-desaturase activity in the mammary gland and possibly other unknown factors.

Brewing by-products: their use as animal feeds.

Brewers grains, a by-product of beer production, are often used as a livestock feed. Because brewers grains provide protein, fiber, and energy, they can be useful in a variety of diets. Protein in brewers grains can meet a significant portion of supplemental protein requirements; in addition, they provide fiber and needed bulk in the diets of ruminants and horses. Brewers grains and other brewers by-products have also been fed to pigs, sheep, and poultry. Currently, the primary market for wet brewers grains is as a dairy cattle feed; however, some may be fed to beef cattle in feedlots. Brewers grains have historically been marketed wet or dry, but wet brewers grains currently make up the majority of the marketed product. Brewers grains provide protein, energy, and fiber in livestock diets, but product variability can influence their utilization and necessitate a testing program to determine nutrient content.

Pentoses and Hydroxycinnamic Acids in Brewer's Spent Grain

In this work, the total pentose (xylose and arabinose) and hydroxycinnamic acid (ferulic and p -coumaric acids) in eight lots of brewer's spent grain preserved by different methods (freeze-drying, oven drying and freezing) has been determined. The total acid-extractable pentose content of the samples varied between 13·0 and 19·5% dry weight for xylose, and 7·2 and 9·6% dry weight for arabinose, whereas the total alkali-extractable hydroxycinnamic acid content varied between 0·17 and 0·24% dry weight for ferulic acid, and between 0·068 and 0·121% dry weight for p -coumaric acid. Significant differences (p<0·05) between lots were found for ferulic and p -coumaric acids. With respect to the different preservation methods, significant differences (P<0·05) were only seen in arabinose content. The content of pentoses and hydroxycinnamic acids in brewer's spent grain has been compared with those from other agro-food residues whose use is also proposed for the enzymatic release of these compounds.

In vitro determination of ruminal dry matter and cell wall degradation, and production of fermentation end-products of various by-products

The samples used in the experiment were nine types of by-products: giant pumpkin, red pepper, melon, broccoli, brewer's grains, fresh and boiled artichoke, lemon peel and orange peel. The dry matter degradability of each by-product was determined by in vitro fermentation with ruminal fluid of the goat. The materials were incubated at 39 oC for 12, 24, 48 and 72 h. At each time, pH, dry matter disappearance, neutral-detergent fibre disappearance, volatile fatty acids, lactic acid and am- monia productions were measured. Approximately 50% of the total dry matter loss of broccoli, melon and peels occurred at 12 h incubation. In addition, the total dry matter loss of the giant pump- kin, fresh and boiled artichoke, and brewer's grains was low ( 70% for all by-products, except for brewer's grains (63.8%), and the propionate proportion was < 20% for all by-products, except for the brewer's grains (21.3%). In conclusion, the ruminal dry matter and cell wall degradations, and production of fermentation end-products by in vi- tro determination offers a convenient method to compare the microbial digestion of the different by- products.

Feeding value, in vitro digestibility and in vitro gas production of different by‐products for ruminant nutrition

AbstractNine by‐products used in animal nutrition were examined for their nutritive value by determining the chemical composition (crude protein, crude fat (ether extract), neutral detergent fibre, acid detergent fibre, lignin), in vitro organic matter digestibility and rumen fermentation kinetics (from gas production curves measured in vitro). The by‐products studied were giant pumpkin, red pepper, stem broccoli, brewer's grain, fresh artichoke, scalded artichoke, lemon peel, orange peel and melon. The nutritive value was very variable, depending on the by‐product and on the process applied to the material during industrial processing. In vitro gas production was measured for 500 mg dry matter in quadruplicate at 39 °C after 6, 12, 24, 36, 48 and 72 h of incubation and fitted to single‐pool exponential equations. The fermentation kinetics indicated that brewer's grain was the only by‐product which fitted well with the p = a + b(1 − e−ct) equation model; all other by‐products had a very fast degradation rate and their gas production fitted the equation p = b(1 − e−c(t−L)), because in the other exponential model a was negative.© 2002 Society of Chemical Industry