Time filter

Source Type

Zebeli Q.,Institute of Animal Nutrition | Zebeli Q.,Research Cluster Animal Gut Health | Metzler-Zebeli B.U.,Research Cluster Animal Gut Health | Ametaj B.N.,University of Alberta
Journal of Dairy Science | Year: 2012

This study examined the extent by which changes in the concentrate level and neutral detergent fiber (NDF) content in the diet as well as the severity of acidotic insult, measured as the duration time of rumen pH below 6.0 and daily mean rumen pH, and the concentration of endotoxin in the rumen fluid are involved in the development of inflammatory conditions in cattle. A meta-analytical approach accounting for inter- and intraexperimental variation was used to generate prediction models, and data from recent studies were used to parameterize these models. A total of 10 recently conducted experiments with 43 different dietary treatments fulfilled the criteria for inclusion in this study. Diets of all of the experiments included in this meta-analysis were based on rapidly degradable grain sources, such as barley and wheat, and the findings of this study apply only to these kinds of diets. Data indicated that greater levels of concentrate in the diet were associated with increased concentrations of rumen endotoxin (R2=0.27), plasma haptoglobin (R2=0.19), and serum amyloid A (SAA) level (R2=0.46). Similar correlations, but in opposite directions, were observed between dietary NDF content and rumen endotoxin (R2=0.39) and plasma SAA concentrations (R2=0.22). The meta-analysis revealed that the relationships between those variables were not linear. Additionally, the breakpoint model fitted to the data of rumen endotoxin, plasma haptoglobin, and SAA indicated the presence of a threshold level of dietary concentrate and NDF, above which those responses became linear to increasing amounts of concentrate or decreasing contents of NDF in the diet. Also, feeding cattle more than 44.1% concentrate or less than 39.2% NDF in the diet was associated with a linear increase in the risk of systemic inflammation. Low daily mean rumen pH (R2=0.38) and duration of rumen pH <6.0 (R2=0.59) were associated with increased concentrations of endotoxin in the rumen fluid; although those events were not always associated with systemic inflammation. Accordingly, only 15 to 21% of the overall variation in the responses of SAA was explained by variables of rumen pH, whereas the concentrate level in the diet accounted for 46% of this variation. In conclusion, data from this study indicated the presence of thresholds of dietary concentrate and NDF levels in the diets based on rapidly fermentable grains beyond which the risk of systemic inflammation in cattle increases linearly. © 2012 American Dairy Science Association. Source

Zebeli Q.,University of Alberta | Zebeli Q.,Institute of Animal Nutrition | Dunn S.M.,Institute of Animal Nutrition | Ametaj B.N.,Institute of Animal Nutrition
Journal of Dairy Science | Year: 2011

Feeding dairy cows diets high in easily degradable carbohydrates increases the incidence of rumen and systemic metabolic disorders; however, the triggering factor is not well understood. In this study, dairy cows were fed 4 different amounts of barley grain-based concentrate at 15, 30, 45, and 60% (dry matter basis) of a total mixed ration to determine whether alterations in the rumen environment would be associated with perturbations of the plasma profile of selected metabolites. In addition, associations among free rumen endotoxin and several plasma metabolites were determined. The study was a replicated 4 × 4 Latin square design with 8 rumen-cannulated lactating dairy cows (60±15 d in milk). Multiple rumen fluid and blood plasma samples were collected and analyzed for pH and rumen fluid endotoxin and for concentrations of glucose, insulin, cholesterol, β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and lactate in the plasma. Rumen pH decreased below 6.0, from 8 to 12h after the morning feeding, with the augmentation of the proportion of concentrate in the diet of ≥30%. Feeding diets with >30% concentrate resulted in a rise of free endotoxin in the rumen fluid (8.87±0.39 μg/mL). Inclusion of 60% concentrate in the total mixed ration was associated with enhanced concentrations of glucose (64.5±1.0 mg/dL) and lactate (540.9±36.5 μmol/L) and lowered cholesterol (265.5±13.7 mg/dL), BHBA (449.1±47.4 μmol/L), and NEFA (138.8±19.1 μEq/L) in the blood plasma. The regression analysis revealed that greater concentrations of plasma lactate and lower concentrations of cholesterol, BHBA, and NEFA were related to the rise of rumen endotoxin. Interestingly, 93% of the increase in the plasma lactate was explained by the rise of rumen endotoxin. Moreover, the analysis revealed inverse relationships of rumen endotoxin with plasma cholesterol (R2=0.47), BHBA (R2=0.37), and NEFA (R2=0.50) and a biphasic response of plasma insulin (R2=0.58). Taken together, feeding dairy cows diets rich in rumen-degradable carbohydrates and low in fiber led to lower rumen pH and a large accumulation of rumen endotoxin; the latter was correlated with perturbations of plasma metabolites allied to carbohydrate and lipid metabolism. © 2011 American Dairy Science Association. Source

Zebeli Q.,Institute of Animal Nutrition | Aschenbach J.R.,Free University of Berlin | Tafaj M.,University of Hohenheim | Boguhn J.,University of Hohenheim | And 2 more authors.
Journal of Dairy Science | Year: 2012

Highly fermentable diets require the inclusion of adequate amounts of fiber to reduce the risk of subacute rumen acidosis (SARA). To assess the adequacy of dietary fiber in dairy cattle, the concept of physically effective neutral detergent fiber (peNDF) has received increasing attention because it amalgamates information on both chemical fiber content and particle size (PS) of the feedstuffs. The nutritional effects of dietary PS and peNDF are complex and involve feed intake behavior (absolute intake and sorting behavior), ruminal mat formation, rumination and salivation, and ruminal motility. Other effects include fermentation characteristics, digesta passage, and nutrient intake and absorption. Moreover, peNDF requirements depend on the fermentability of the starch source (i.e., starch type and endosperm structure). To date, the incomplete understanding of these complex interactions has prevented the establishment of peNDF as a routine method to determine dietary fiber adequacy so far. Therefore, this review is intended to analyze the quantitative effects of and interactions among forage PS, peNDF, and diet fermentability with regard to rumen metabolism and prevention of SARA, and aims to give an overview of the latest achievements in the estimation of dietary fiber adequacy in high-producing dairy cattle. Recently developed models that synthesize the effects of both peNDF and fermentable starch on rumen metabolism appear to provide an appropriate basis for estimation of dietary fiber adequacy in high-producing dairy cows. Data suggest that a period lasting more than 5 to 6h/d during which ruminal pH is <5.8 should be avoided to minimize health disturbances due to SARA. The knowledge generated from these modeling approaches recommends that average amounts of 31.2% peNDF inclusive particles >1.18mm (i.e., peNDF >1.18) or 18.5% peNDF inclusive particles >8mm (i.e., peNDF >8) in the diet (DM basis) are required. However, inclusion of a concentration of peNDF >8 in the diet beyond 14.9% of diet DM may lower DM intake level. As such, more research is warranted to develop efficient feeding strategies that encourage inclusion of energy-dense diets without the need to increase their content in peNDF above the threshold that leads to lower DM intake. The latter would require strategies that modulate the fermentability characteristics of the diet and promote absorption and metabolic capacity of ruminal epithelia of dairy cows. © 2012 American Dairy Science Association. Source

Ametaj B.N.,University of Alberta | Sivaraman S.,University of Alberta | Dunn S.M.,University of Alberta | Zebeli Q.,Institute of Animal Nutrition
Innate Immunity | Year: 2012

The objective of this study was to evaluate the effects of repeated oral exposure to LPS on humoral immune responses of periparturient dairy cows. Sixteen Holstein cows were assigned to two treatment groups 2 wk before the expected day of parturition. Cows were administered orally, twice weekly at wk -2, -1 and +1 around parturition, with the following treatments: 3 ml saline; or 3 ml of saline containing LPS from Escherichia coli 0111:B4. The amount of LPS administered during wk -2, -1, and +1 was 0.01, 0.05, or 0.1 μg/kg body weight, respectively. Multiple blood samples were collected by jugular vein and various immune and clinical variables were measured. Results indicated that, on one hand, concentrations of plasma IgG anti-LPS Abs decreased (P < 0.01) and those of IgM anti-LPS Abs increased (P < 0.01) in cows treated with oral LPS. On the other hand, there were no overall differences (P > 0.05) in the concentrations of serum amyloid A, LPS-binding protein, haptoglobin, cortisol, IgA anti-LPS Abs in the plasma, feed intake, body temperature and rumen contractions rate between the control and treatment groups. To our knowledge, this study is the first to show that repeated oral administration with LPS from E. coli 0111:B4 has the potential to stimulate humoral immune responses in periparturient dairy cows. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav. Source

Nasrollahi S.M.,Isfahan University of Technology | Khorvash M.,Isfahan University of Technology | Ghorbani G.R.,Isfahan University of Technology | Teimouri-Yansari A.,University of Agriculture and Natural Resource Science of Sari | And 2 more authors.
Animal | Year: 2012

This study investigated the effects of, and interactions between, dietary grain source and marginal changes in alfalfa hay (AH) particle size (PS) on digestive processes of dairy cows. A total of eight Holstein dairy cows (175 days in milk) were allocated in a replicated 4 ã- 4 Latin square design with four 21-day periods. The experiment was a 2 ã- 2 factorial arrangement with two levels of theoretical PS of AH (fine = 15 mm or long = 30 mm) each combined with two different sources of cereal grains (barley grain alone or barley plus corn grain in a 50 : 50 ratio). Results showed that cows consuming diets supplemented with corn had greater dry matter and nutrient intakes (P < 0.01), independent of forage PS. In addition, the apparent digestibility of fiber fractions was greater for diets supplemented with corn (P = 0.01). The feeding of barley grain-based diets was associated with greater apparent digestibility of non-fiber carbohydrates, and this variable was even greater when long AH was fed (P = 0.04). Moreover, the feeding of long AH resulted in longer time spent eating (P = 0.03) and higher pH (P < 0.01), as well as a tendency for higher acetate-to-propionate ratio in the rumen fluid (P = 0.06) at 3 h post feeding. In conclusion, the results indicated that the marginal increase of PS of AH may prolong eating time and improve rumen fermentation, particularly in diets based on barley grain. Partial substitution of barley grain by corn can improve feed intake and fiber digestibility in mid-lactation dairy cows. © Copyright The Animal Consortium 2012. Source

Discover hidden collaborations