A pinboard by
Elsayed Mickdam

Lecturer (post doctor), South valley university, Faculty of veterinary medicine


Lactic acid treatment of grains modify structure of starch and improve rumen phosphorus degradation

Continuous genetic improvement of dairy cows for milk production increased their energy need. Therefore, feeding high grain diets has become a common practice. Feeding high grain diets to ruminants has sequential consequences on animal health and environment due to increasing phosphorus(P) excretion into the environment. To deal with both issues, one of the goals of ruminant nutrition research is to modulate degradability of starch-rich cereal grains in the gut, especially in the rumen where intensive microbial degradation of macronutrients as well as utilization of micronutrients take place. At best, the modulation should result in slowing down ruminal degradation of starch while increasing ruminal degradability and thus bioavailability of phytate P. In this context, there has been research dealing with mechanical or thermal processing techniques (e.g., pelleting, roasting and rolling) as well as chemical methods of cereal grains (e.g., ammonia, formaldehyde, sodium hydroxide and fibrolytic enzymes). These processing techniques may exert desirable effects on slowing down ruminal starch degradability, but they can impair the solubility of phytate P and therefore suppress ruminal phytate degradation in the rumen. To date, lactic acid (LA), citric acid (CA) and tannic acid (TA) have been the main organic acids used for treating grains. Treatment of grains with organic acids could change the chemical composition of grain starch. Accordingly, treatment of barley grain with 5% LA largely enhanced the resistant starch. Furthermore, studies showed that treating barley with 1 and 5% LA can reduce the rate of enzymatic digestion of LA-treated grain starch and modulate rumen microbial fermentation in vitro by enhancing propionate formation and lowering branched-chain SCFA and caproate in the ruminal fluid.Increased content of slowly degradable starch in the grains after acid processing may assist in slowing down ruminal starch degradation while increasing bypass starch from the rumen to the lower gut. These effects could be beneficial in terms of ruminal pH stabilization and thus acid treatment may decrease the risk of developing digestive diseases. In addition, LA treatment of grains enhances the ruminal hydrolysis of of phytate in the grains. As such, decreasing needs for inorganic P supplementation. This work aimed at unmasking the effects of treatment of grains with 5% LA the concentration efficient in enhancing phytate liberation and changing starch structure


Feeding barley grain-rich diets altered electrophysiological properties and permeability of the ruminal wall in a goat model.

Abstract: High-producing ruminants are commonly fed large amounts of concentrate to meet their high energy demands for rapid growth or high milk production. However, this feeding strategy can severely impair rumen functioning, leading to subacute ruminal acidosis. Subacute ruminal acidosis might have consequences for electrophysiological properties by changing the net ion transfer and permeability of ruminal epithelia, which may increase the uptake of toxic compounds generated in the rumen into the systemic circulation. The objective of the present study was to investigate the effects of excessive barley feeding on the electrophysiological and barrier functions of the ruminal epithelium and serum inflammation and ketogenesis markers after a long-term feeding challenge, using growing goats as a ruminant model. A feeding trial was carried out with growing goats allocated to 1 of the 3 groups (n=5-6 animals/group), with diets consisting exclusively of hay (control diet) or hay with 30 or 60% barley grain. Samples of the ventral ruminal epithelium were taken after euthanasia and instantly subjected to Ussing chamber experiments, where electrophysiological properties of the epithelium were measured in parallel with the permeability of marker molecules of different sizes [fluorescein 5(6)-isothiocyanate and horseradish peroxidase] from luminal to apical side. Additionally, ruminal fluid and blood samples were taken at the beginning of the experiment as well as shortly before euthanasia. Ruminal fluid samples were analyzed for volatile fatty acids and pH, whereas blood samples were analyzed for lipopolysaccharide, serum amyloid A, and β-hydroxybutyrate. Electrophysiological data indicated that barley feeding increased the epithelial short-circuit current compared with the control. Tissue conductance also increased with dietary barley inclusion. As shown with both marker molecules, permeability of ruminal epithelia increased with barley inclusion in the diet. Despite a lowered ruminal pH associated with increased volatile fatty acids (such as propionate and butyrate) concentrations as well as altered epithelial properties in response to high-grain feeding, no signs of inflammation became apparent, as blood serum amyloid A concentrations remained unaffected by diet. However, greater amounts of grain in the diet were associated with a quadratic increase in lipopolysaccharide concentration in the serum. Also, increasing the amounts of barley grain in the diet resulted in a tendency to quadratically augment serum concentrations of β-hydroxybutyrate and, hence, the alimentary ketogenesis. Further studies are needed to clarify the role of barley inclusion in the development of subacute ruminal acidosis in relation to ruminal epithelial damage and the translocation of toxic compounds in vivo.

Pub.: 14 Feb '13, Pinned: 27 Aug '17

Grain-rich diets differently alter ruminal and colonic abundance of microbial populations and lipopolysaccharide in goats.

Abstract: High grain feeding has been associated with ruminal pH depression and microbial dysbiosis in cattle. Yet, the impact of high grain feeding on the caprine rumen and hindgut microbial community and lipopolysaccharide (LPS) release is largely unknown. Therefore, the objective was to investigate the effect of increasing dietary levels of barley grain on the microbial composition and LPS concentrations in the rumen and colon of goats. Effects were compared with respect to the responses of ruminal and colonic pH and short-chain fatty acid (SCFA) generation. Growing goats (n = 5-6) were fed diets containing 0, 30, or 60% coarsely ground barley grain for 6 weeks. Ruminal ciliate protozoa were counted with Bürker counting chamber, and quantitative PCR was used to compare bacterial populations. Increasing dietary grain level linearly increased (P < 0.05) ruminal numbers of entodiniomorphids. With the 60% grain diet, there was a reduction in ruminal abundance of the genus Prevotella and Fibrobacter succinogenes, whereas the ruminal abundance of Lactobacillus spp. increased compared to the 0 and 30% grain diets (P < 0.05). In the colon, abundance of the genus Prevotella and F. succinogenes increased (P < 0.05) in goats fed the 60% grain diet compared to those fed the other diets. Colonic abundance of Clostridium cluster I was related to the presence of grain in the diet. Ruminal LPS concentration decreased (P < 0.05) in response to the 60% grain diet, whereas its colonic concentration increased in response to the same diet (P < 0.05). Present results provide first insight on the adaptive response of rumen protozoa and rumen and colonic bacterial populations to increasing dietary levels of grain in goats. Although luminal pH largely affects microbial populations, fermentable substrate flow to the caprine hindgut may have played a greater role for colonic bacterial populations in the present study.

Pub.: 12 Mar '13, Pinned: 27 Aug '17

Treatment of grain with organic acids at 2 different dietary phosphorus levels modulates ruminal microbial community structure and fermentation patterns in vitro.

Abstract: Recent data indicate positive effects of treating grain with citric (CAc) or lactic acid (LAc) on the hydrolysis of phytate phosphorus (P) and fermentation products of the grain. This study used a semicontinuous rumen simulation technique to evaluate the effects of processing of barley with 50.25 g/L (wt/vol) CAc or 76.25 g/L LAc on microbial composition, metabolic fermentation profile, and nutrient degradation at low or high dietary P supply. The low P diet [3.1g of P per kg of dry matter (DM) of dietary P sources only] was not supplemented with inorganic P, whereas the high P diet was supplemented with 0.5 g of inorganic P per kg of DM through mineral premix and 870 mg of inorganic P/d per incubation fermenter via artificial saliva. Target microbes were determined using quantitative PCR. Data showed depression of total bacteria but not of total protozoa or short-chain fatty acid (SCFA) concentration with the low P diet. In addition, the low P diet lowered the relative abundance of Ruminococcus albus and decreased neutral detergent fiber (NDF) degradation and acetate proportion, but increased the abundance of several predominantly noncellulolytic bacterial species and anaerobic fungi. Treatment of grain with LAc increased the abundance of total bacteria in the low P diet only, and this effect was associated with a greater concentration of SCFA in the ruminal fluid. Interestingly, in the low P diet, CAc treatment of barley increased the most prevalent bacterial group, the genus Prevotella, in ruminal fluid and increased NDF degradation to the same extent as did inorganic P supplementation in the high P diet. Treatment with either CAc or LAc lowered the abundance of Megasphaera elsdenii but only in the low P diet. On the other hand, CAc treatment increased the proportion of acetate in the low P diet, whereas LAc treatment decreased this variable at both dietary P levels. The propionate proportion was significantly increased by LAc at both P levels, whereas butyrate increased only with the low P diet. Treatments with CAc or LAc reduced the degradation of CP and ammonia concentration compared with the control diet at both P levels. In conclusion, the beneficial effects of CAc and LAc treatment on specific ruminal microbes, fermentation profile, and fiber degradation in the low P diet suggest the potential for the treatment to compensate for the lack of inorganic P supplementation in vitro. Further research is warranted to determine the extent to which the treatment can alleviate the shortage of inorganic P supplementation under in vivo conditions.

Pub.: 25 Aug '15, Pinned: 27 Aug '17

Fortification of dried distillers grains plus solubles with grape seed meal in the diet modulates methane mitigation and rumen microbiota in Rusitec.

Abstract: The role of dried distillers grains plus solubles (DDGS) and associative effects of different levels of grape seed meal (GSM) fortified in DDGS, used as both protein and energy sources in the diet, on ruminal fermentation and microbiota were investigated using rumen-simulation technique. All diets consisted of hay and concentrate mixture with a ratio of 48:52 [dry matter (DM) basis], but were different in the concentrate composition. The control diet contained soybean meal (13.5% of diet DM) and barley grain (37%), whereas DDGS treatments, unfortified DDGS (19.5% of diet DM), or DDGS fortified with GSM, either at 1, 5, 10, or 20% were used entirely in place of soybean meal and part of barley grain at a 19.5 to 25% inclusion level. All diets had similar DM, organic matter, and crude protein contents, but consisted of increasing neutral detergent fiber and decreasing nonfiber carbohydrates levels with DDGS-GSM inclusion. Compared with the soy-based control diet, the unfortified DDGS treatment elevated ammonia concentration (19.1%) of rumen fluid associated with greater crude protein degradation (~19.5%). Methane formation decreased with increasing GSM fortification levels (≥ 5%) in DDGS by which the methane concentration significantly decreased by 18.9 to 23.4 and 12.8 to 17.6% compared with control and unfortified DDGS, respectively. Compared with control, unfortified DDGS decreased butyrate proportion, and GSM fortification in the diet further decreased this variable. The proportions of genus Prevotella and Clostridium cluster XIVa were enhanced by the presence of DDGS without any associative effect of GSM fortification. The abundance of methanogenic archaea was similar, but their composition differed among treatments; whereas Methanosphaera spp. remained unchanged, proportion of Methanobrevibacter spp. decreased in DDGS-based diets, being the lowest with 20% GSM inclusion. The abundance of Ruminococcus flavefaciens, anaerobic fungi, and protozoa were decreased by the GSM inclusion. As revealed by principal component analysis, these variables were the microorganisms associated with the methane formation. Grape seed meal fortification level in the diet decreased DM and organic matter degradation, but this effect was more related to a depression of nonfiber carbohydrates degradation. It can be concluded that DDGS fortified with GSM can favorably modulate ruminal fermentation.

Pub.: 05 Feb '15, Pinned: 27 Aug '17