Low Roughage Diet Research Articles

The effect of Megasphaera elsdenii on faecal pH and blood pH, TCO2 and blood lactate concentration in horses transitioned to a high concentrate low roughage diet

The effect of <i>Megasphaera elsdenii</i> on faecal <scp>pH</scp> and blood <scp>pH</scp>, <scp>TCO2</scp> and blood lactate concentration in horses transitioned to a high concentrate low roughage diet

352 Effects of Including a Novel High-Anthocyanin Corn Cob Meal in a High-Roughage Diet on Performance and Gas Flux of Beef Cattle

Abstract Methane (CH4) is a greenhouse gas emitted by cattle that is produced as a byproduct of ruminal fermentation. Dietary inclusion of anthocyanins has previously decreased in vitro CH4 production from both high- and low-roughage diets. Anthocyanins potentially sequester hydrogen in the rumen which may limit CH4 production from methanogenic bacteria. As such, feeding anthocyanins represents a promising CH4 mitigation strategy. Thus, the objective of this preliminary experiment was to determine the effects of replacing conventional [CONV; 0.04 mg anthocyanin×g-1 of dry matter (DM)] corn cob meal (CCM) with a novel high-anthocyanin (Hi-A) CCM [TAMZ101 corn hybrid (4.99 mg anthocyanin×g-1 DM; Texas A&amp;M AgriLife Research; Lubbock, TX)] in a high-roughage (40% DM) diet on growth performance and gas flux of beef cattle. Steers (n =14; average initial body weight = 286 kg ± 17 kg) were trained to individual Calan bunks and randomly assigned to dietary treatments on d 0 using a completely randomized design, where 20% of total diet DM was either Hi-A or CONV CCM. The trial consisted of a 63-d feeding period in which carbon dioxide (CO2) emission, CH4 emission, and oxygen (O2) consumption (g×animal×d-1) were measured using a GreenFeed system (C-Lock Inc.; Rapid City, SD). Statistical analyses were conducted using JMP Pro v.16 (SAS Institute Inc.; Cary, NC) where individual animal served as the experimental unit and treatment was a fixed effect. Cook’s distance values were used to identify and remove outliers for each individual response variable. Statistical significance was set at P ≤ 0.05 with a tendency toward significance defined as 0.05 &amp;lt; P ≤ 0.10. Due to insufficient statistical power, 10.2% and 5.7% numeric increases were statistically undetectable in total dry matter intake (DMI; P = 0.13; 1-ß = 0.31) and average daily gain (ADG; P = 0.19; 1-ß = 0.25) when CONV CCM was replaced with Hi-A CCM. Similarly, marginal numeric differences in feed efficiency, CO2 emission, daily CH4 emission, and O2 consumption were statistically undetectable across treatments (P ≥ 0.18; 1-ß ≤ 0.22). Numeric differences in DMI of steers fed Hi-A CCM contributed to a 7.5% decrease (P = 0.05; 1-ß = 0.51) in CH4 yield (g CH4×kg DMI-1) when compared with steers fed CONV CCM. Treatment did not affect CH4 emission intensity (g CH4×kg ADG-1; P = 0.26; 1-ß = 0.19). Results from this preliminary experiment and a previous in vitro experiment indicate that anthocyanins from Hi-A CCM have CH4 mitigation potential in high-roughage diets. Further research is warranted to determine if anthocyanins are effective at reducing CH4 yield across a range of diet compositions and if anthocyanins from Hi-A CCM can be extracted, condensed, and repackaged into a delivery system that is both economically and logistically feasible.

48 Evaluation of Antimicrobial Activities of Phytophenols Against Bacterial Pathogens That Cause Liver Abscesses in Feedlot Cattle

Abstract Liver abscesses occur in finishing cattle fed high-grain, low-roughage diets. Cattle with abscessed livers do not show any clinical signs and are detected only at slaughter. Liver abscesses, which account for 67% of all liver abnormalities in cattle slaughtered in the United States, are of major economic concern to the beef industry. Fusobacterium necrophorum, Trueperella pyogenes, and Salmonella enterica, particularly the serotype Lubbock, are the main etiologic agents. Currently, the control of liver abscesses is based on in-feed use of antibiotics. The emergence and dissemination of antimicrobial resistance to antibiotics use in animals is a public health concern. Plant-based phenolic compounds, called phytophenols, are known to have antimicrobial properties. Our objectives were to evaluate antimicrobial activities of phytophenols on the liver abscess bacterial pathogens. Phytophenols extracted from rosemary, green tea, grapeseed, organic goji berry, and green coffee were selected for testing. The phytophenols were extracted using 75% aqueous acetone and total phenolic content was determined by a spectrophotometric analysis. Bacteria were cultured in Mueller-Hinton broth (S. Lubbock and T. pyogenes) or anaerobic brain-heart infusion broth (F. necrophorum with and without phytophenols, at 6, 12, 24, and 48 hours and bacterial concentrations were determined. If phytophenol was inhibitory, a micro-broth dilution method was used to quantify the inhibition. Phytophenols from green tea, grape seed, and rosemary inhibited T. pyogenes. Further studies are ongoing to investigate different concentrations of phenolic compounds on the pathogens. Phytophenols that inhibit the pathogens may have the potential to be used as feed additives to prevent liver abscesses.

38 Evaluation of Sorghum Phenolic Compounds for Their Antimicrobial Activities Against Liver Abscess Causing Pathogens in Feedlot Cattle

Abstract Liver abscesses occur in finishing cattle fed high-grain, low-roughage diets. Cattle with abscessed livers seldom show any clinical signs and are detected only at the time of slaughter. Liver abscesses are of significant economic concern to the feedlot industry. Liver abscesses comprise, on average, 67% of all liver abnormalities in cattle slaughtered in the United States with a prevalence of 10–20% and may reduce the value of the beef carcass up to $38 per animal with the most severe abscesses. There are four causative agents of the disease including the two subspecies of Fusobacterium necrophorum, ssp. necrophorum and ssp. funduliforme, Trueperella pyogenes, and Salmonella enterica. Tylosin, supplemented in the feed, is the most commonly used antibiotic in the feedlot industry to prevent liver abscesses. Because of the concerns about antimicrobial resistance, there is a need to find an effective alternative to this antibiotic, and sorghum grain extracts, which are high in phenolic compounds, may have the potential to be used as natural antibiotic alternatives. Our objectives were to investigate the efficacy of phenolic extracts from black, sumac, brown, and burgundy sorghums on liver abscess pathogens. The sorghum phenolics were extracted using 75% aqueous acetone and total phenolic content was determined by spectrophotometrically. Bacterial strains were cultured in Mueller-Hinton broth (Salmonella and Trueperella pyogenes) or anaerobic brain-heart infusion broth (Fusobacterium) with and without sorghum extracts (1 mg/ml) at 12, 24, and 48 hours and bacterial concentrations were determined. If the compound was inhibitory, a micro-broth dilution method was used to quantify the inhibitory activity. Both black and sumac sorghum phenolics inhibited growth of all four bacterial species. Further studies are ongoing to investigate different concentrations and phenolic compounds from varieties of sorghum grains on the liver abscess pathogens.

Nutritive value for high-yielding lactating cows of barley silage and hay as a substitute for wheat silage and hay in low-roughage diets

We assessed the effects of replacing wheat silage and hay with barley silage and hay in total mixed rations (TMRs) on: eating behavior, digestibility, and performance of individually fed high-yielding lactating cows. The barley cultivar Ma’anit and the wheat cultivar Omer were grown by dryland farming (210 mm precipitation) in a commercial field with sandy loam soil. The two cultivars were harvested simultaneously for silage or hay at a similar dry matter (DM) content (35.6%). Barley yields exceeded wheat yields by 19% (5.68 vs. 4.79 t DM/ha, P = 0.01). Two-thirds of each crop's DM yield was chopped and transferred for direct ensiling in polyethylene-wrapped bales, and one-third was wilted in the field for 2 weeks and then pressed into hay bales. The chemical composition and in-vitro DM digestibility of the wheat and barley silages and hays were similar. The two experimental TMRs contained either barley silage (280 g/kg DM) and hay (60 g/kg DM) or similar contents of wheat silage and hay, as the sole source of roughage. High-yielding multiparous Israeli Holstein cows were paired into two experimental groups of 21 cows each and fed either wheat- or barley-based TMR ad libitum for 28 days. DM intake of cows fed the wheat TMR was higher than that of the barley TMR-fed cows (28.0 vs. 27.5 kg/day) due to a faster eating rate (137.9 vs. 132.9 g DM/min) and larger meal size. Energy corrected milk production was similar in the two groups (42.4 and 42.8 kg/day), while milk fat yield was higher in barley-fed cows than wheat-fed cows (1.62 vs. 1.57 kg/day). Daily rumination time of the barley-fed cows was longer (577 vs. 537 min/day) and their rumen pH higher during the day and night (P < 0.01) compared to wheat-fed cows. Consequently, in-vivo DM digestibility and neutral detergent fiber digestibility were higher in the barley-fed cows. Our results thus show the benefit of barley as an alternative forage crop to wheat in semiarid regions, and its advantage as a substitute for wheat as silage and hay for high-yielding lactating cows’ TMR.

Development of prediction equation for methane-related traits in beef cattle under high concentrate diets.

The objective of this study was to develop a prediction equation for methane-related traits in beef cattle and evaluate this equation using datasets with different cattle breeds and roughage rates. Enteric methane emission (CH4 , l/day) was measured using open-circuit respiration chambers. Dry matter intake (DMI, kg/day), body weight (BW, kg), daily gain (DG, kg), total digestible nutrients (TDN, %DMI), and roughage rate (Rrate, %) were used as independent variables, and methane-related traits-CH4 , CH4 per DMI (CH4 /DMI, l/kg), and methane conversion factor (MCF, %)-were used as dependent variables. The best-fit equations to predict methane-related traits using a total of 76 records were CH4 =-676.7+0.04194×BW+29.88×DMI+7.883×TDN+4.367×Rrate, CH4 /DMI=-52.24-1.193×10-3 ×BW-5.905×DG+1.077×TDN+0.5008×Rrate, and MCF=-11.43-5.308×10-4 ×BW-1.223×DG+0.2336×TDN+0.1157×Rrate. The predictive ability of the developed equations differed between roughage rates but not between breeds. For CH4 , the predictive ability of the developed equations was better compared with previously reported equations in the low roughage rate dataset, but not in the high roughage rate dataset. Our results suggest that the developed equations of methane-related traits can be applied in beef cattle fed with low roughage diets.

Eating behavior, milk production, rumination, and digestibility characteristics of high- and low-efficiency lactating cows fed a low-roughage diet

This study aimed to identify individual characteristics differing among high-efficiency (HEf; upper 20%, n = 31), low-efficiency (LEf; lower 20%, n = 31), and mid-efficiency (MEf, 60% n = 93) lactating cows. Primiparous (37) and multiparous (118) high-producing milking cows at 30 to 180 d in milk were fed individually a low-roughage diet [31.6% of dry matter (DM)] for 4 wk. Daily average DM intake, rate of eating, visit duration, meal size, and daily rumination time were higher in LEf compared with HEf cows. On the other hand, HEf cows exhibited higher digestibility of DM, crude protein, and neutral detergent fiber than the LEf cows. Daily eating time was similar in the HEf and LEf groups and higher than that of the MEf cows. Visit and meal frequency, average visit and meal duration, daily lying time, and pedometer activity were similar in the HEf, LEf, and MEf groups. The HEf cows produced 1.75% more milk, but similar energy-corrected milk compared with the LEf cows. Milk fat and protein content were lower by 1.8 and 3.8%, respectively, in the HEf cows than in the LEf group. Body weight (BW) and BW gain were similar in the 3 efficiency groups. Diurnal distribution of DM intake showed 6 distinct major meals, each composed of 1.1 to 1.6 visits. Higher intake peaks (greater meal size) were found in the LEf cows compared with the HEf group. Daily DM intake was highly correlated (affected) with energy-corrected milk production (r = 0.61), BW (r = 0.4), eating rate (r = 0.57), and visit size (r = 0.54). Energy balance showed that the lower efficiency of the LEf cows was attributed to their excess heat production and energy loss.

An unexpected acoustic indicator of positive emotions in horses.

Indicators of positive emotions are still scarce and many proposed behavioural markers have proven ambiguous. Studies established a link between acoustic signals and emitter’s internal state, but few related to positive emotions and still fewer considered non-vocal sounds. One of them, the snort, is shared by several perrisodactyls and has been associated to positive contexts in these species. We hypothesized that this could be also the case in horses. In this species, there is a clear need for a thorough description of non-vocal acoustic signals (snorts, snores or blows are often used interchangeably) but overall this sound produced by nostrils during expiration has up to now been mostly considered as having a hygienic function. However, observations revealed that snorts were produced more in some individuals than in others, without relationship with air conditions. We observed 48 horses living in two “extreme” conditions: restricted conditions (single stall, low roughage diet) and naturalistic conditions (stable groups in pasture). The immediate place (e.g. stall/pasture) and the behavioural/postural (behaviour performed/ears positions) contexts of snort production were observed. We additionally performed an evaluation of the welfare state, using validated behavioural (e.g. stereotypies) and postural (e.g. overall ears positions) welfare indicators. The results show that 1) snort production was significantly associated with situations known to be positive for horses (e.g. feeding in pasture) and with a positive internal state (ears in forward or sidewards positions), 2) the riding school horses produced twice as many snorts when in pasture than in stall, 3) the naturalistic population emitted significantly more snorts than riding school ones in comparable contexts, 4) the frequency of snorts was negatively correlated with the composite total chronic stress score (TCSS, reflecting compromised welfare based on the horse’s rank on the different indicators): the lower the TCSS, the higher the snort rate. Snorts therefore appear as reliable indicators of positive emotions.

Domestic cattle (Bos taurus taurus) are motivated to obtain forage and demonstrate contrafreeloading.

Domestic cattle (Bos taurus taurus) are adapted to digest high-roughage diets, but in confinement they are commonly fed low-roughage, high-energy diets. This practice may leave cattle with an unfulfilled need to consume forage. A way to quantify motivation is to require animals to work to access a resource. Using this method, we evaluated cattle motivation to obtain forage when fed high- or low-roughage diets during and 30 d before the study. Individual heifers were fed Sudan grass (Sorghum × drummondii) hay (high roughage, n = 6) or a diet with 12% forage (as fed, low roughage, n = 6) in an open feed trough. In a second trough, 200 g/d of Sudan grass hay were fed behind a push gate, to which additional weight was added daily until heifers no longer pushed. We predicted heifers would push heavier weights, show a shorter latency, and spend more time pushing the gate when fed a low- vs. high-roughage diet. Indeed, heifers fed a low-roughage diet pushed the gate immediately after hay delivery (1.7 min) and much sooner than those fed a high-roughage diet (75.7 min). On the day before they no longer pushed the gate, latency for heifers in the low-roughage treatment remained only 3.2 min after hay delivery. The suddenness with which they ceased pushing the next day suggests they were unable to move heavier weights to express their motivation. This may explain why maximum weight pushed and time spent pushing the gate did not differ between treatments. The gate pushing by heifers with unrestricted hay access is the first demonstration by cattle of contrafreeloading: performing work to obtain a resource that is simultaneously available for free. In conclusion, consuming forage is important to cattle and is affected by both their primary diet and an internal motivation to work to obtain feed.

Effect of dietary roughage to concentrate ratios with sunflower oil supplement, on digestibility, rumen fermentation, milk production and milk fatty acid profile of dairy goats.

ABSTRACTThe aim of this study was to evaluate the effect of high- or low-concentrate ratio in the present of sunflower oil (SFO) in all tested diets on rumen fermentation, nutrient utilization, and fatty acid profile in milk fat of lactating goat’s. Eighteen Zaribi goats (averaged 43 kg ± 1Kg body weight) were divided into three similar groups (6 goats each) for use in the feeding trial, which lasted 90 days. A randomized complete block designs was applied. Experimental rations comprised iso-nitrogenous and iso caloric based on concentrate feed mixture (CFM) and berseem hay in three roughage to concentrate ratios as follow: 50:50(T1), 55:45(T2) and60:40(T3). The three rations were supplemented with 30 g SFO /kg of DM intakeThe results showed that dry matter intake (P < 0.05) decreased with increasing the ratio of roughage by 26.9% and 41.0 % for T2 and T3 compared with T1, respectively. There were no significant differences among groups in DM digestibility, while OM and EE digestibility (P < 0.05) were higher in T1 ration (high concentrate) than both T2 and T3 rations (lower concentrate). All nutrients digestibility significantly (P < 0.05) increased with T1 (high concentrate and low roughage) than T3 (low concentrate and high roughage), while, no significant difference between T1 and T2 rations. On the other hand, TDN values did not affected by concentrate to roughage ratios. While, DCP decreased in T2 and T3 by increasing roughage ratio. High-roughage diet (T2 and T3) resulted in a lower rumen pH and higher total rumen VFA concentration, whereas, high concentrate diet increased rumen pH and decreased rumen VFA concentration. High-concentrate diet increased rumen ammonia-N (P < 0.05) and molar proportion of acetate to propionate. There were no significant differences in milk yield, as 4% fat corrected milk, among animals fed the tested rations supplemented with sunflower oil (SFO) as source of unsaturated fatty acids. The high roughage diets (T2 and T3) resulted in increase in linoleic (c18:2) and linolenic acid (c18:3) concentration by 69 and 45%, respectively compared with control (T1). Also, kids of T1 group had significant (P < 0.05) higher birth weight than other groups, while, there were no significant difference in daily gain among kids of the three groups.In conclusion, high concentrate diet could have better milk yield and protein percentage, while have less fat % and yield, compare to high roughage diet. Suckling kids could benefit more gain with dams fed high concentrate diet. Low roughage diet also develop better fat profile in milk. However, more studies are needed to identify the best economic combination for feeding dairy goats.

Effect of high and low roughage total mixed ration diets on rumen metabolites and enzymatic profiles in crossbred cattle and buffaloes

Aim::A comparative study was conducted on crossbred cattle and buffaloes to investigate the effect of feeding high and low roughage total mixed ration (TMR) diets on rumen metabolites and enzymatic profiles.Materials and Methods::Three rumen-fistulated crossbred cattle and buffalo were randomly assigned as per 3×3 switch over design for 21-days. Three TMR diets consisting of concentrate mixture, wheat straw and green maize fodder in the ratios of (T1) 60:20:20, (T2) 40:30:30, and (T3) 20:40:40, respectively, were fed to the animals ad libitum. Rumen liquor samples were collected at 0, 2, 4, 6, and 8 h post feeding for the estimation of rumen biochemical parameters on 2 consecutive days in each trial.Results::The lactic acid concentration and pH value were comparable in both species and treatments. Feed intake (99.77±2.51 g/kg body weight), ruminal ammonia nitrogen, and total nitrogen were significantly (p<0.05) higher in buffalo and in treatment group fed with high concentrate diet. Production of total volatile fatty acids (VFAs) was non-significant (p>0.05) among treatments and significantly (p<0.05) greater in crossbred cattle than buffaloes. Molar proportions of individual VFAs propionate (C3), propionate:butyrate (C3:C4), and (acetate+butyrate):propionate ([C2+C4]:C3) ratio in both crossbred cattle and buffalo were not affected by high or low roughage diet, but percentage of acetate and butyrate varied significantly (p<0.05) among treatment groups. Activities of microbial enzymes were comparable among species and different treatment groups. A total number of rumen protozoa were significantly (p<0.05) higher in crossbred cattle than buffaloes along with significantly (p<0.05) higher population in animal fed with high concentrate diet (T1).Conclusion::Rumen microbial population and fermentation depend on constituents of the treatment diet. However, microbial enzyme activity remains similar among species and different treatments. High concentrate diet increases number of rumen protozoa, and the number is higher in crossbred cattle than buffaloes.

Effects of different roughage sources and feeding levels on adipogenesis of ovine adipocytes.

The objective of the present study was to conduct an adipogenic evaluation of different roughage sources and feeding levels during ruminant adipocyte differentiation in vitro. Six wether sheep were divided into a timothy hay feeding group (TFG, n = 3) and an Italian ryegrass straw feeding group (IFG, n = 3). The sheep were fed high-roughage (HR), medium roughage (MR) and low-roughage (LR) diets in a one-way layout design each over a 6-day period. Sheep serum samples collected on the last day of each dietary treatment were added to an adipogenic induction medium for differentiation of preadipocytes derived from sheep subcutaneous adipose tissue. The cytoplasmic lipid accumulations in the TFG serum-treated preadipocytes were significantly higher than those of the IFG-serum treated preadipocytes on day 12. Messenger RNA expression of CCAAT/enhancer-binding protein (C/EBP)-α, C/EBP-β, C/EBP-δ, fatty-acid-binding protein (aP2) and stearoyl-coenzyme A desaturase (SCD) were regulated by each serum treatment. This study shows that different roughage source diets and roughage-to-concentrate ratio diets can regulate adipocyte differentiation via ruminant blood composition.

Utilisation of high- and low-roughage diets by a local and an exotic breed of sheep: intake, growth and digestive efficiency

In the context of sustainable agriculture, there is renewed interest in livestock breeds considered well adapted to harsh environments. Churra da Terra Quente (CTQ), the most important sheep breed raised in the Northeast region of Portugal, are considered to be well adapted to their environment which is characterised by marked fluctuations in feed quality and abundance. However, supporting such a claim is difficult because of large gaps in our knowledge, including the importance of the stage of maturity in influencing the efficiency of using different resources. A study was conducted to determine whether feed intake, digestion and growth differed between CTQ and the Ile-de-France (IF) exotic breed at the same stage of maturity, under two contrasting diets. Twenty female lambs of each of the CTQ and IF breeds, 102±3 and 121±4 days old respectively, with 20.7±1.4 and 33.6±1.1kg of body weight (BW), corresponding to proportionally 0.45 of estimated mature BW (MBW), were allocated randomly within breed to a high- or a low-roughage diet (hay:concentrate feed proportions of 75:25 and 30:70; HR and LR, respectively) and fed ad libitum. Dry matter intake (DMI) and growth were measured from proportionally 0.45–0.65 of MBW. Then, digestibility was measured in 5 animals per diet and breed. DMI was higher (P<0.001) in the IF breed (1132 vs. 797g/day), but when scaled by MBW no differences (P>0.1) were observed between breeds. A breed × diet interaction (P<0.01) was observed: on the HR diet, CTQ had higher DMI than IF, the opposite being observed with diet LR (P<0.001). The IF animals grew faster (167 vs. 92g/day; P<0.001), but needed more time to achieve 0.65 MBW (111 vs. 95 days; P=0.025). However, similar feed efficiency (P=0.880) was found between breeds and the differences in growth and time taken to mature were explained by the MBW of the breeds. Digestibility of organic matter (OM) measured in IF animals was 2.7 and 0.8 percent units higher for diets HR and LR, respectively, but breeds did not differ in neutral detergent fibre or energy digestibility. No differences between breeds were observed in the efficiency of microbial-N flow, rumen pH or in the molar proportions of acetate, propionate or butyrate. However, IF animals had higher rumen ammonia-N (P=0.026) and total volatile fatty acids (P=0.022) concentrations, irrespective of the diet. Data of the current experiment suggest that CTQ has a higher capacity to ingest fibre-rich diets, but not to digest fibre.

Changes in methane emission, rumen fermentation in response to diet and microbial interactions

To evaluate relative contributions of different microbial groups in rumen, the mono-culture (i.e. bacteria, protozoa and fungi) and co-cultures (i.e. bacterial–protozoal, fungal–protozoal and bacterial–fungal) were tested in vitro using high and low roughage diets. Total gas and methane were higher in bacterial–fungal and bacterial–protozoal co-cultures, while lower in fungal–protozoal than controls (high and low roughage with complete rumen consortia; control 1 and 2, respectively). Digestibility and total volatile fatty acids were lower in bacterial–fungal co-culture with both high and low roughage diets. Methanogens decreased in bacterial–fungal co-culture with high roughage. With high roughage, counts were lower for bacteria with bacterial–protozoal, protozoa with fungal–protozoal, and fungi with the bacterial–fungal co-cultures. Total gas was higher in bacterial mono-culture with low roughage, but methane was not detected in any mono-culture. Digestibility and total volatile fatty acids were significantly lowered with protozoal mono-culture. Methanogens reduced significantly in mono-cultures with high roughage diet than control 1. Defaunation reduced methanogens without significantly affecting rumen fermentation.

Ruminal acidosis in feedlot cattle: Interplay between feed ingredients, rumen function and feeding behavior (a review)

Ruminal acidosis in feedlot cattle is a common metabolic disorder of digestive origin with significant economic and welfare implications. The main risk factors are high grain, low roughage diets because of their high rate and extent of degradation by rumen microbes. Diet formulation should therefore consider the proportion, method of processing and type of grain; the proportion, fiber concentration and particle size of forages; and the use of feed additives. Grain and forage characteristics, and feed additives, may determine the rate and amount of organic acids produced in the rumen. In addition, diet formulation may also affect feeding behavior, i.e. feed intake and chewing behaviors, which has a great influence on ruminal fluid acid–base balance. Feeding characteristics associated with low ruminal fluid pH are: high dry matter intake and ingestion of large meals because of the greater amount of acid production per period of time, high eating rate because of lower feed ensalivation, short time spent chewing while eating and ruminating because of lower daily saliva production, and large variations in feeding behavior patterns throughout the day such as less frequent meals and rumination. The ruminal acid–base balance requires synchronization in time between acid production and neutralization through saliva, as well as elimination through absorption, wash-out from the rumen, and metabolization. Greater proportions of roughage in the diet and greater particle size leads to slower eating rate and longer chewing time which favors saliva production, and smaller meals which reduce the amount of acid production. Adaptation of feeding behavior to diets with greater proportion of concentrates also plays an important role, as smaller meals and more even distribution of intake throughout the day lead to a better synchronization in time between acid production and elimination or neutralization. Monensin increases the frequency of meals and reduces meal size which is beneficial for ruminal fluid pH, whereas sodium bicarbonate at high concentrations produces the opposite effects and reduces rumination. In addition to diet formulation, feeding management and the social environment may also affect feeding behavior and consequently, ruminal fluid pH. Delivering the feed twice daily results in better synchronization in time between feed intake (acid production), rumination (saliva production), and elimination of fermentation products from the rumen. In contrast, feeding programs that restrict feed amount and time available allow animals to become hungry, whereas restricted feeding space increases competition among group mates. Both situations lead to fewer and larger meals eaten at a faster rate, and consequently, greater risk of ruminal acidosis.

Motivation for hay: Effects of a pelleted diet on behavior and physiology of horses

The natural diet of free-ranging horses is grass, which is typically high in fiber and calorically dilute, however diets for high performance domestic horses are often low in fiber and calorically dense. The aim of the study was to determine the motivation of horses for hay when fed a low roughage diet. Their motivation could be used to determine if low roughage diets compromise the welfare of horses. Eight mares were fed two different diets in counterbalanced order: ad libitum orchard grass hay; a complete pelleted feed (pellets). Each trial lasted three weeks, with a one-week transition period between diets. To determine the motivation of horses for fiber they were taught to press a panel to obtain a food reward. The fixed ratio (FR) was increased using a progressive ratio ((1,2,4,7,11…) technique. When fed pellets, the horses worked for a median FR of 1 (Range=1-497) to attain pellets, and when fed hay, they worked for a median FR of 25.5 (4-497) to attain pellets. When fed hay, the horses worked for a median FR of 0 (0-0) to attain hay, and when fed pellets, they worked for a FR of 13 (2-79) to attain hay. These results indicate a greater motivation for hay, a high fiber diet, when fed a low fiber diet. The horses spent 10 (5-19.4)% of their time during a 24-hour period eating pellets compared to 61.5 (29-76) % of their time eating hay. Horses spent 58% of their time standing when fed the pellets and only 37% of their time standing when fed hay. Searching behavior (i.e. sifting through wood shaving bedding for food particles) took up 11.5 (1.4-32) % of the horse's day when fed pellets, but only 1.2 (0-3.5) % of the daily time budget when fed hay. Horses chew more times when eating a hay diet (43,476chews/day) than when eating a pellet diet (10,036chews/day). Fecal pH was lower in horses fed the pelleted diet.

Effect of Megasphaera elsdenii NCIMB 41125 drenching on health and performance of steers fed high and low roughage diets in the feedlot

Lactate utilising bacteria (LUB) assist in reducing the risk of ruminal lactate acidosis when high concentrate diets are fed to feedlot cattle. Ruminal lactate acidosis can lead to lower animal performance and morbidity. Preliminary studies suggested that the strain, Megasphaera elsdenii (M.e.) NCIMB 41125, is a particularly potent LUB. The potential of M.e.NCIMB 41125 to improve the health and performance of feedlot cattle was investigated. Four hundred and forty eight Bonsmara steers (ca. 240 kg) were used in a 100-day feeding trial. Half the steers received at processing 200 mL M.e.NCIMB 41125 per os (LY) and the other half no LUB (LN). The diets in each of these treatments were divided into a low roughage (2%) (RL) and high roughage (8%) (RH) diet. The effects of LY vs. LN, RL vs. RH as main effects and their respective interactions (LYRL, LYRH, LNRL & LNRH) were compared in terms of morbidity, feedlot performance and carcass characteristics. The steers were weighed at two week intervals, feed was offered daily and the orts were removed weekly from each pen. The faecal consistency score and incidence of morbidity were recorded. At slaughter, carcass data were collected and the health status of the liver and rumen epithelium was assessed. Steers dosed with M.e.NCIMB 41125 had a 5.6% better average daily gain (ADG) during weeks 3 - 5 (2.09 kg/day vs. 1.98 kg/day for LY and LN, respectively). Feed conversion ratio (FCR, Weeks 1 - 13) was better for the steers fed the RL than the RH treatment (4.72 kg/kg vs. 4.99 kg/kg for RL and RH, respectively). Steers on the LNRH treatment during weeks 3 - 5 used more feed per kg gain than steers on the other treatments (5.39 kg/kg for LNRH vs. 4.74 kg/kg and 4.72 kg/kg for LYRL and LNRL, respectively). More steers (21) on the LNRL treatment were treated for morbidity than on the other treatments (8, 7 and 5 for LYRL, LYRH and LNRH, respectively). In general, animal performance was not improved by dosing with M.e.NCIMB 41125, but since ADG was improved in the immediate postadaptation phase (weeks 3 - 5) and morbidity levels were lower on the low roughage diet, dosing of steers on low roughage, lactate acidosis-prone, diets with M.e.NCIMB 41125 should prove useful.Keywords: Beef cattle, lactic acid utilising bacteria, acidosis, morbidity

Roughage for Diets Fed to Weaned Dairy Calves

ABSTRACT Two trials were conducted to test the effect of low-quality roughage level, roughage source, and CP concentration in diets of 8- to 12-wk-old Holstein steer calves. In trial 1, 96 steers (initially 79 ± 2 kg) were fed daily either A) a free-choice (FC) mixture of 96.5% textured feed (13.5% CP) blended with 4.5% chopped hay, B) a FC mixture of 96.5% textured feed (16.5% CP) blended with 4.5% chopped hay, C) 2.27 kg of 13.5% CP textured feed with FC chopped grass hay, or D) 2.27 kg of 16.5% CP textured feed with FC chopped grass hay. In trial 2, 96 steers (initially 80 ± 1 kg) were fed 16.5% CP diets consisting of a textured diet containing either A) 5% chopped hay, B) 15% chopped hay, C) 5% cottonseed hulls (CSH), or D) 15% CSH. In both trials, calves fed 4.5 or 5% of either dietary roughage had greater ADG than calves fed FC hay or 15% hay or CSH because of reduced intake. In trial 1, ADG was greater for calves fed textured feeds with 16.5% CP than for calves fed feeds with 13.5% CP, regardless of the amount of roughage fed. As-fed textured feed intakes averaged 3.17 kg/d in the low-roughage diets and were more than typical recommendations to limit intake to 2.27 to 2.73 kg/d. Limiting concentrate intake to 2.27 kg/d in 8- to 12-wk-old calves in these trials reduced ADG, and ADG was maximal at 5% roughage in the diet.

Adult Obesity and Diet

We are what we eat. Although rather clichéd, the level of fat in the diet of a population does directly mirror the incidence of heart disease and there are many other dietary factors which have both direct and indirect links with disease. For example, excess ingestion of salt is associated with high blood pressure; low roughage diets are associated with bowel cancer; ingestion of infected beef causes Creutzfeldt—Jakob disease; eggs may carry salmonella and some food additives have been associated with hyperactivity.

Responses of lactating dairy cows to sodium bicarbonate or sodium bentonite in low forage diet

Dietary sodium bicarbonate or sodium bentonite has been used in lactating cow diets to aid ration adjustment. Addition of sodium bicarbonate increased intake and milk production for cows fed high concentrate diets in the first two months after parturition (Erdman et al., 1980). Addition of dietary buffers such as sodium bicarbonate and sodium bentonite increased molar percentage of acetate and reduced propionate in dairy cows. Milk fat percentage was increased by sodium bicarbonate in dairy cows when fed low roughage diets (Erdman, 1988). The objective of the present study was to investigate the effect of sodium bicarbonate or sodium bentonite in diets of high yielding dairy cows on milk yield, milk composition, and faecal pH.