Feedlot Bloat Research Articles

Comparison of linear and non-linear decision boundaries to detect feedlot bloat using intensive data collection systems on Angus × Hereford steers

Ruminal tympany (bloat) has long been an issue for large and small livestock operations. Though improvements in feedlot management practices have reduced its occurrence, it is still highly prevalent and is known to detrimentally affect animal performance, welfare, and in many instances, lead to animal death. Current decision support systems and diet formulation software omit the inclusion of bloat prediction based on animal performance. Here, we aim to predict bloat incidence in implanted and non-implanted feedlot steers from performance data comparing linear (LDB) and non-linear decision boundaries. Eighteen crossbred Angus × Hereford steers: BW (491.13 ± 25.78 kg) and age (12 ± 1 mo) were randomly distributed into implanted and non-implanted treatments. All animals were randomly assigned to one of two pens fit with automated monitoring systems for BW, freshwater intake, and water intake behavior: water intake event visit, no water intake event visit (NWIE), and time spent drinking. DM intake (DMI) was individually recorded from all animals through the Calan Gate system for 135 d (30 d adaptation, 105 d experimental diet). Incidences of bloat were recorded as bloat instances regardless of severity to ensure that early onset detection of bloat was recorded and properly identified in predictive models. Logistic regression with a binomial distribution and a logit link function was utilized to predict the incidences of bloat through LDB. Feature selection and penalization of coefficients were explored through L1 (sum of absolute values) and L2 (sum of squares) penalization to avoid overfitting of models. Additional NLDB and a non-parametric LDB are examined for prediction. Accuracy, specificity, and sensitivity were high for the models reported. No significant differences were observed between LDB and NLDB, with the highest specificity (predicting bloat) value of 0.820 for stepwise feature selection algorithms, and a value of 0.832 for the artificial neural network. Highest accuracy was 0.829 for ridge regression, and 0.847 for the random forest with hyperparameter tuning. DM intake, BW, and NWIE were the three most important variables for the prediction of feedlot bloat showing clear drops in DMI and BW and increases in NWIE when animals bloated. The lack of difference in predictive performance between LDB and NLDB highlights the often-overlooked concept that machine learning algorithms are not always the only/best modeling technique. Additionally, the models reported herein carry acceptable predictive performance for inclusion into management decisions that reduce bloat incidences in feedlot cattle.

Recent advances in research in the rumen bloat of ruminant animals fed high-concentrate diets.

Rumen bloat is the most common digestive disorder in fattening ruminants, which is responsible for around 2-3 % of deaths in the ruminants industry and is therefore considered to be a serious threat to ruminant farming. The root cause of rumen bloat caused by feeding high concentrate dies would be attributed to the production of a large amount of stable foam during the fattening period. The exact mechanism of rumen foam formation has yet to be investigated. Proteins, polysaccharides and carboxylates derived from feed, and synthesized by microbes during the rumen fermentation may act as foaming agents or stabilizers in the formation progress of rumen foam. Supplementation of condensed tannins and other additives can be an effective way to prevent feedlot bloat induced by feeding high concentrate diets.

40. Predictive equations to detect incidence of feedlot bloat in finishing cattle in individual cattle management systems

40. Predictive equations to detect incidence of feedlot bloat in finishing cattle in individual cattle management systems

Frothy bloat in ruminants: Cause, occurrence, and mitigation strategies

A number of pasture and feedlot management practices and feed additives have reduced, but not eliminated the occurrence of frothy bloat in cattle. Bloat occurs as a result of complex interactions among the feed, rumen microbial populations and the host. Factors such as soluble protein levels in the feed, rates of feed digestion, bacterial slime production and digesta passage rates, all play a role in the likelihood of bloat. Practices that lower soluble protein levels and retard the rate of feed digestion can reduce the risk of bloat as can grazing alfalfa at advanced stages of maturity. Similarly, processing grain to an optimal particle size, inclusion of ionophores in the diet and allowing a period of adaptation during the transition from forage to grain diets lowers the incidence of feedlot bloat. Pluronic detergents which disperse the stable froth in the rumen can be effective in the treatment and prevention of both pasture and feedlot bloat. The sporadic and unpredictable nature of frothy bloat often makes it unrealistic for preventative measures to be applied to all animals at risk. Genetic engineering of condensed tannin containing, bloat-safe varieties of alfalfa and clover may eliminate the occurrence of bloat in cattle grazing these forages. Understanding the factors that regulate intake and contribute to bacterial slime production could provide additional insight into feedlot bloat. Comparing of the rumen microbial metagenomes and metatrascriptomes of bloated and non-bloated animals should provide a fresh perspective on the role of rumen microbial populations in bloat. The key to the successful prevention of frothy bloat lies in a thorough understanding of the feed, microbial and host factors involved in the condition.

ASAS Centennial Paper: Contributions in the Journal of Animal Science to understanding cattle metabolic and digestive disorders1

Acute and subacute ruminal acidosis, bloat, liver abscesses, and polioencephalomalacia (PEM) were reviewed with respect to contributions published in the Journal of Animal Science (JAS) regarding these metabolic and digestive disorders in beef cattle. Increased grain feeding and expansion of the feedlot industry in the 1960s led to considerable research on acidosis, and early publications defined ruminal changes with acute acidosis. The concept of subacute acidosis was developed in the 1970s. Significant research was published during the 1980s and 1990s on adaptation to high-grain diets, effects of ionophores, and the development of model systems to study ruminal and metabolic changes in acidosis. Since 2000, JAS publications on acidosis have largely focused on individual animal variability in response to acid loads and the role of management strategies in controlling acidosis. Increased grain feeding also was associated with an increase in the incidence of liver abscesses, which were quickly linked to insults to the ruminal epithelium associated with acidosis. The role of antibiotics, particularly tylosin, in decreasing the incidence and severity of liver abscesses was a significant contribution of JAS publications during the 1970s and 1980s. Papers on bloat were among the earliest published in JAS related to metabolic and digestive disorders in cattle. Noteworthy accomplishments in bloat research chronicled in JAS include the nature of ruminal contents in legume and feedlot bloat, the role of plant fractions and microbial populations in the development of bloat, and the efficacy of poloxalene, ionophores, and, more recently, condensed tannins in decreasing the incidence and severity of bloat. Although less research has been published on PEM in JAS, early publications highlighting the association between PEM and ruminal acidity and the role of thiaminase in certain forms of the disorder, as well as more recent publications related to the role of sulfur in the development of PEM, are noteworthy contributions. Since the 1940s, outstanding and often-cited review articles have made JAS a highly visible source of information on these disorders. Thus, JAS has played a significant role as a repository for information pertaining to metabolic and digestive disorders in cattle and other ruminants, and it will no doubt continue to be a premier resource for information on these conditions during the second century of the American Society of Animal Science.

Effects of lauric acid on physical, chemical and microbial characteristics in the rumen of steers on a high grain diet

ABSTRACTThe effects of being fed lauric acid on rumen characteristics were evaluated in a double 3 × 3 Latin square design using six Holstein steers with ruminal cannulas on a high grain diet. The steers were fed commercial concentrate (8.7 kg/day/steer) with one of three levels of lauric acid (0, 25 or 50 g/day/steer) and timothy hay (1.8 kg/day/steer). The feed intake and digestibility were determined. Ruminal fluid was collected at 3 h after feeding to determine chemical, physical and microbial parameters. An in vitro pure culture study was performed to determine the effects of lauric acid on Streptococcus bovis, a potent bloat‐ and acidosis‐promoting rumen bacterium. There were no differences in feed intake and digestibility among the treatments. The proportion of butyrate and the viscosity of the rumen fluid tended to be lowered (P < 0.08 and P < 0.09, respectively) and the stable ingesta volume increase was significantly decreased (P < 0.01) by the lauric acid feed. The abundance of protozoa and bacteria did not differ among the treatments. In the in vitro study, the growth of S. bovis was inhibited by the lauric acid (100 nmol/L) but it showed an adaptive growth to lauric acid in long‐term subculturing. The S. bovis that had adapted to lauric acid showed decreased viscosity and lactate production (P < 0.01) in culture with sucrose. These results indicate that supplemental lauric acid added to a high grain diet improves physical properties, possibly by altering the metabolic activity of S. bovis, and it may prevent the occurrence of feedlot bloat and acidosis in beef cattle.

Nutritionally related disorders affecting feedlot cattle

Digestive disorders account for approximately 25 to 33% of deaths in feedlot cattle and likely contribute to decreased performance and efficiency of production. A variety of nutritional, management, genetic, behavioural, and environmental factors seem to be involved in the development of metabolic disorders in feedlot cattle. Excessive production of acid in the rumen is often either the cause of or a significant contributing factor to metabolic and nutritional disorders, including acute or sub-acute (chronic) acidosis, liver abscesses, and feedlot bloat. Decreasing the percentage of highly fermentable concentrates in feedlot diets by increasing roughage level or limiting feed intake should decrease the incidence of these disorders, but this approach is usually not economically feasible. Careful feed bunk management is often thought to be important for decreasing the incidence of nutritionally related disorders, but research to support its importance is limited and conflicting. Certain feed additives like ionophores seem to be effective for decreasing the incidence of acidosis and feedlot bloat, presumably through decreased total feed intake, smaller and more frequent meals, and direct effects on the ruminal microbial population. The incidence of liver abscesses can be decreased by the feeding of various antibiotics. Polioencephalomalacia (PEM) can result from several causes, including thiamine deficiency; however, recent data suggests that overproduction of H2S in the rumen is an important cause of PEM when intakes (feed and water) of sulfur are high in feedlot cattle. Key words: Beef cattle, acidosis, bloat, liver abscesses, polioencephalomalacia

A review of bloat in feedlot cattle.

Improvements in feedlot management practices and the use of various feed additives have reduced, but not eliminated, the occurrence of bloat in feedlot cattle. Feedlot bloat reduces the profitability of production by compromising animal performance and more directly by causing fatalities. In feedlots, bloat is associated with the ingestion of large amounts of rapidly fermented cereal grain and destabilization of the microbial populations of the rumen. An abundance of rapidly fermented carbohydrate allows acid-tolerant bacteria (e.g., Streptococcus bovis and Lactobacillus spp.) to proliferate and produce excessive quantities of fermentation acids. As a result, ruminal pH becomes exceedingly low, and this impairs rumen motility. Further, the excessive production of mucopolysaccharide or "slime" increases the viscosity of ruminal fluid and stabilizes the foam implicated in frothy feedlot bloat. Although protocols have been developed to treat feedlot bloat, the most profitable approach is to use management strategies to reduce its likelihood. Amount of roughage, grain processing techniques, selection of cereal grain (e.g., corn, barley, and wheat), dietary adaptation periods, and various additives (e.g., ionophores) can influence the occurrence of bloat in feedlot cattle. Successful management of these factors depends on a thorough understanding of the behavioral, dietary, and microbial events that precipitate bloat in feedlot cattle.

Application of research findings and summary of research needs: Bud Britton Memorial Symposium on Metabolic Disorders of Feedlot Cattle.

Updated research findings with acidosis, feedlot bloat, liver abscesses, and sudden death syndromes were presented at the Bud Britton Memorial Symposium on Metabolic Disorders of Feedlot Cattle. Possible industry applications include the need to establish guidelines for use of clostridial vaccines in feedlot cattle, further assessment of the relationship between acidosis and polioencephalomalacia, examination of the effects of various ionophores on the incidence of metabolic disorders, and evaluation of the effects of feed bunk management and limit- and restricted-feeding programs on the incidence of metabolic disorders. A multidisciplinary approach among researchers, consulting nutritionists and veterinarians, and feedlot managers will be required for effective progress in research and in the application of research findings. Areas suggested for further research include 1) assessment of feed consumption patterns and social behavior of cattle in large-pen, feedlot settings; 2) evaluation of the relationship between feed intake management systems (feed bunk management programs, limit- and programmed-feeding) and the incidence of metabolic disorders, including delineation of the role of variability in feed intake in the etiology of such disorders; 3) efforts to improve antemortem and postmortem diagnosis, and to establish standardized regional or national epidemiological databases for various metabolic disorders; 4) ascertaining the accuracy of diagnosis of metabolic disorders and determining the relationship of previous health history of animals to the incidence of metabolic disorders; 5) further defining ruminal and intestinal microbiology as it relates to metabolic disorders and deeper evaluation of metabolic changes that occur with such disorders; 6) continued appraisal of the effects of grain processing and specific feed ingredients and nutrients on metabolic disorders, and development of new feed additives to control or prevent these disorders; and 7) application of biotechnology to develop grain varieties with altered nutrient degradation profiles that decrease the propensity for disastrous acid loads in the rumen, feed-grade enzymes and probiotics that modify nutrient digestion or microbial profiles in the rumen and intestine, and specific strains of ruminal bacteria and protozoa that alter ruminal and metabolic conditions that may precipitate metabolic disorders.

動, 植, 鉱物性油脂がめん羊の第一胃内容液のin vitro泡沫安定性に及ぼす影響

In most cases, feedlot bloat is caused by the development of stable foam in the contents of the rumen. Therefore, it is effective to control stable foam formation for the prevention and treatment of feedlot bloat. Animal, vegetable and mineral oils, and several surfactants have been used as anti-foaming agents. This study was conducted to determine the effects of several oils on the in vitro foam stability of rumen fluid in sheep.

Interaction of Protein Percent with Caloric Density and Protein Source for Lactating Cows

Experiment 1 was to test effect of three ratios of energy to protein in complete mixed diets for 36 lactating cows in three, 28-d periods. Energy was varied with cottonseed hulls, pelleted ground corrugated boxes, and a mixture of the two. Crude protein was varied with soybean meal to give energy:crude protein of 5.7, 5.0, and 4.6 for each energy amount. Cottonseed meal was compared with soybean meal in corrugated box diets. Feed intake was much higher with cottonseed hulls, and appreciable feedlot bloat resulted from pelleted ground corrugated box diets. Data adjusted to equal feed intake showed significant effect of energy to crude protein ratio on milk yield and improved digestion of organic matter with soybean meal vs. cottonseed meal.Experiment 2 tested the hypothesis that lactating cows consuming high-protein alfalfa may benefit from supplemental protein. Diets were 50% forage. Six diets were 14 or 18% crude protein in three ratios of alfalfa hay to corn silage (0:100, 50:50, 100:0). Additional corn silage diets were to compare: 14 versus 18% protein from distiller's dried grains with solubles only and with .5 or .9% urea (four diets); two 14% protein diets compared .6% added potassium chloride with or without .5% urea. Thirty-six Holstein cows in early lactation received one of the 12 diets in each of three 28-d periods. Distiller's grains with solubles markedly depressed milk yield (2.2 kg/d) and milk protein (.22%); heat damage of distiller's grains was evident. Protein interacted with alfalfa so gain in milk from 18 versus 14% increased from .55 to 1.36 to 2.66 kg/d as alfalfa changed from 0 to 50 to 100%. Thus, crude protein of alfalfa was not as effective as that from soybean meal in supporting milk yield.

Effect of Lasalocid or Monensin on feedlot (grain) bloat in cattle (1983)

Lasalocid or monensin (600 mg per 1000 lb body weight daily) was tested on cattle bloating on high grain diets. Bloat was reduced 92% by Lasalocid and 64% by monensin. When fed throughout the finishing period, lasalocid at 300 mg per 1000 lb body weight effectively prevented bloat from developing. However, 600 mg was required to control bloat in cattle that were already bloating.

Microbial characteristics of ruminal fluid from feedlot bloat beef cattle.

Rumen samples from bloating steers had volatile fatty acids (VFA) concentrations high in acetate and low in propionate so that the acetate/ propionate ratio was consistently higher in bloating animals than in healthy ones. The ruminal pH values in bloated steers were compatible with those in healthy steers. Ammonia concentrations were higher in bloated steers than in healthy ones. There were no essential differences in the rates of gas production in vitro by rumen fluid between bloated and healthy steers. The total count and generic composition of rumen ciliates were similar in all steers and not likely to correlate with bloat. In contrast, although the total counts of bacteria in bloated steers were of the same order as those from healthy steers, the constitution of microflora was greatly affected by the development of bloat: gram-negative cocci (0.3-1.0μm), gram-positive cocci (0.5-1.1μm) and gram-positive small rods {(0.45-0.65μm)×(0.65-1.2μm)} increased, while gram-negative small rods {(0.35-0.7μm)×(0.9-2.0μm)} decreased in bloating steers.

BLOAT IN FEEDLOT CATTLE: EFFECTS ON RUMEN FUNCTION OF ADDING 4% SODIUM CHLORIDE TO A CONCENTRATE DIET

Four fistulated cows were given alfalfa hay or all-concentrate diets containing either 0.5% or 4.0% NaCl (salt). The low-salt diet leads to the development of rumen conditions associated with bloat. When given the low-salt concentrate diet, cows had rumen fluid with lower pH and protozoal counts, and higher viscosity, soluble carbohydrate concentration, and dry matter content than when they were given alfalfa hay or the high-salt concentrate diet. Massive lysis of bacterial cells was observed in rumen digesta from cows on the low-salt diet and intact cells were full of reserve carbohydrate granules and were surrounded by thickened fibrillar capsules. These changes were largely absent in cows on the other two diets. Water intake and the total water content of the rumen were lower with the low-salt diet than with the other diets. The flow of water through the rumen was highest with alfalfa hay, lowest with the low-salt diet, and intermediate with the high-salt diet. It was concluded that adding 4.0% NaCl to an all-concentrate diet of a type implicated in feedlot bloat increased the flow of material from the rumen and, in so doing, appeared to alter fermentation in such a way as to oppose development of conditions that lead to bloat.

Alkaline phosphatase activity of rumen bacteria.

Of the 54 strains of rumen bacteria examined for alkaline phosphatase (APase) production, 9 of 33 gram-negative strains and none of 21 gram-positive strains produced the enzyme. The APase of the cells of the three strains of Bacteroides ruminicola that produced significant amounts of the enzyme was located in the periplasmic area of the cell envelope, whereas the enzyme was located in the strains of Selenomonas ruminantium and Succinivibrio dextrinosolvens was associated with the outer membrane. The localization of APase production in the cells of natural populations of rumen bacteria from hay-fed sheep was accomplished by reaction product deposition, and both the proportion of APase-producing bacteria and the location of the enzyme in the cell envelope of the producing cells could be determined. We suggest that this procedure is useful in detecting shifts in the bacterial population and the release of cell-bound APase that accompany feedlot bloat and other sequelae of dietary manipulation in ruminants.

VISCOSITY AND PROTEIN AND CARBOHYDRATE CONTENTS OF SALIVAS AND THEIR POSSIBLE RELATION TO BLOAT SUSCEPTIBILITY IN CATTLE

Mixed saliva was collected at the cardia of fistulated cows before they received their morning feed. Viscosity of the saliva decreased with time after collection and the rate of decrease was markedly accelerated by vigorous stirring, or by the addition of filtered or centrifuged rumen fluid or neuraminidase. Dialyzed saliva was freeze-dried, and the dry material obtained was analyzed for protein, carbohydrate, and sialic acid and subjected to polyacrylamide gel electrophoresis. Cows with a record of susceptibility to bloat tended to produce saliva with lower viscosity and lower dry matter content than cows not susceptible to bloat. Furthermore, the dry matter of saliva from bloat-susceptible cows was higher in protein and lower in carbohydrate and sialic acid and exhibited fewer glycoprotein bands after electrophoresis than that from cows not susceptible to bloat. This suggests that composition of saliva, particularly the pattern of glycoprotein bands, might be useful to indicate susceptibility to bloat. However, because of the rapid reduction of viscosity of saliva due to the action of bacterial neuraminidase on salivary glycoprotein, saliva secreted by cattle cannot contribute to the rise in rumen fluid viscosity characteristically associated with feedlot bloat.

Agglutinating immunoglobulins to encapsulated Streptococcus bovis in bovine serum and saliva and a possible relation to feedlot bloat

All bovine sera tested contained agglutinating immunoglobulins against encapsulated Streptococcus bovis. The immunoglobulins also were shown in predominantly parotid saliva. Cells grown in broth with added carbohydrate (sucrose) produced extracellular dextran (capsule) and were agglutinated by sera and saliva, but S. bovis cells grown in absence of carbohydrate were not agglutinated. The reacting material was established by adsorption with mono-specific anti-bovine gamma globulin to be an immunoglobulin. Sephadex adsorption studies showed the immunoglobulin specific to extracellular dextran. Sephadex adsorption also provided a way to isolate these immunoglobulins. Purified capsular dextran demonstrated a precipitin reaction with serum and saliva preparations. Because S. bovis capsule has been implicated in feedlot bloat, it is possible that antibodies reaching the rumen in bovine saliva may affect bloat.

Frothy feedlot bloat in cattle: production of extracellular polysaccharides and development of viscosity in cultures of Streptococcus bovis.

Streptococcus bovis was cultured in a synthetic medium with three concentrations of sucrose. Initial viscosity of the media was 1.5 centipoise (cp). After incubation for 8 h, the viscosity of the medium with 0.5% sucrose was unchanged, that with 3% sucrose had increased to 8 cp, and that with 6% sucrose to 112 cp. Similar results were found with a rumen fluid medium. A slimy material, responsible for increased viscosity of these cultures, was digested by dextranase. The material appeared as a complex system of intercellular fibers when viewed under the electron microscope after freeze-etching. With proteins and other polymers released from lysed bacteria, this slimy material may contribute directly to increased viscosity and foam formation. In addition to these intercellular fibers, each cell was surrounded by a fibrous capsule that was not digested by dextranase. This capsule stained with lead citrate and uranyl acetate, but not with ruthenium red. The amount of capsular material produced was similar whether the media contained 0.5, 3.0, or 6% sucrose.

INFLUENCE OF PARTICLE SIZE OF CONCENTRATE ON RUMEN CONDITIONS ASSOCIATED WITH FEEDLOT BLOAT

Some rumen characteristics associated with bloat were measured in identical twin cows fed diets of coarse and fine particle size (geometric mean particle size of 715 and 388 μ). A foamy condition developed in the rumen of all cows fed the fine diet and in one of those fed the coarse diet on the 2nd day of the experiment. In vitro gas production 1 h after feeding was 3.46 ml/h per g dry matter (DM) on fine feed and 2.35 ml/h per g DM on the coarse (P < 0.05). During the 1st week of feeding the pH value of rumen of cows fed the coarse diet was 4.86 and that of cows fed the fine diet was 4.75. During the 2nd week the pH of both were lower at 4.53 and 4.12 (P > 0.05). There was no difference in the numbers of Streptococcus bovis present in the rumen attributable to the particle size of the diet. The number of S. bovis increased with an increasing proportion of concentrate fed until the cows were changed to the all-concentrate diet, when numbers declined sharply to a low level. S. bovis does not appear to be a primary cause of feedlot bloat.

Bloat in cattle. XVI. Development and application of techniques for selecting drugs to prevent feedlot bloat.

THE prevention of bloat has been the object of many studies, the majority involving use of surface-active agents or antibiotics. Because feedlot bloat is essentially the frothy type (Meyer and Bartley, 1971), the introduction of synthetic detergents provided an abundance of surfactants that could be tested for froth inhibition in the rumen. However, to test in vivo the multitude of drugs available would be a prohibitive task. This paper describes a three-step program for screening drugs for prevention of feedlot bloat. The first step (Experiment 1) determines the effect of the drug on in vitro froth production, surface tension, relative viscosity, and microbial activity. In this step, 235 drugs were tested. The second step (Experiment 2) consists of administering potential bloat preventives to rumen-fistulated cattle fed a feed-lot bloat-provoking ration. The effect of 54 drugs on in vivo rumen froth production was evaluated. The last step (Experiment 3) in testing the efficacy of a bloat prophylactic was to administer the drug as a feed additive to cattle bloating on an all-concentrate ration.