Efficacy of Megasphaera elsdenii inoculation in subacute ruminal acidosis in cattle

Two consecutive experiments were carried out to determine efficacy of Megasphaera elsdenii inoculation in alleviation of subacute ruminal acidosis (SARA). In the first experiment, SARA was induced by feeding corn‐ and wheat‐based diets (20%, 40%, 60% and 80% of TMR, DM basis) in six ruminally cannulated heifers. Continuous pH was obtained using data loggers embedded in rumen. In corn (80%)‐ and wheat (60%)‐based diets ruminal pH ranged from 5.2 to 5.6 for 7.77 and 5.93 hr. In the second experiment (5 day), M. elsdenii (200 ml; 2.4 x 10¹⁰ cfu/ml) was inoculated during the first two days. During the SARA induction period, M. elsdenii and S. bovis in rumen liquor were more abundant in wheat‐based feeding (7.97 and 8.77) than in corn‐based feeding (7.06 and 7.95 per ml, log basis; p < 0.0001 for both). M. elsdenii inoculation increased total volatile fatty acids (VFA) concentration when corn‐based diet was fed, whereas it decreased total VFA concentration when wheat‐based diet was fed (p < 0.004). There was a decrease in the propionic acid proportion (24.04%–19.08%; p < 0.002), whereas no alteration in lactate and ammonia concentrations was observed. M. elsdenii inoculation increased protozoa count (from 5.39 to 5.55 per ml, log basis; p < 0.009) and decreased S. bovis count (from 9.18 to 7.95 per ml, log basis; p < 0.0001). The results suggest that M. elsdenii inoculation may help prevent SARA depending on dietary grain through altering rumen flora as reflected by a decrease in S. bovis count and an increase in protozoa count.     

Prevalence and consequences of subacute ruminal acidosis in German dairy herds

Background

The prevalence and the clinical consequences of subacute ruminal acidosis (SARA) in dairy cows are still poorly understood. In order to evaluate the prevalence of SARA, 26 German dairy farms were included in a field study. In each herd, between 11 and 14 lactating dairy cows were examined for their ruminal pH using rumenocentesis. Milk production data and farm management characteristics were recorded. Each farm was scored for lameness prevalence among lactating animals, and body condition score was recorded three times four to five weeks apart in all animals examined. Farms were grouped on basis of ruminal pH and compared for lameness, body condition, milk production parameters and style of management. Animals were grouped on basis of their measured ruminal pH and compared accordingly for milk production parameters and body condition score.

Results

Of 315 cows examined, 63 individuals (20%) exhibited a ruminal pH of ≤ 5.5 at time of rumenocentesis. Of 26 farms examined, eleven farms had three or more of their cows experiencing a ruminal pH of ≤ 5.5 and were classified as likely experiencing subacute ruminal acidosis. These farms tended to be bigger than the others and offered less lying space to the lactating cows. There was no clear tendency regarding lameness. Among individual cows, animals with a low ruminal pH of ≤ 5.5 were found to be in significantly poorer body condition than animals with higher pH values (p < 0,05).

Conclusions

The study shows 11 out of 26 of herds likely experiencing SARA. Bigger herds tend to be at a higher risk for SARA, while individuals with low ruminal pH tend to be lower in body condition. The study points to the importance of management in preventing SARA.     

奶牛亚急性瘤胃中毒(SARA)防治措施

奶牛亚急性瘤胃酸中毒(SARA)在临床上发病慢、病程时间长、病症隐匿.在大规模的养殖中,造成经济损失的主要原因不是急性酸中毒,而是亚急性瘤胃酸中毒.SARA造成的经济损失主要表现在产奶量、乳脂率下降和繁殖率低下(Oetzel,2000),主要的临床症状是间歇性腹泻、瘤胃炎、肝脓肿以及蹄叶炎(Kleen等,2003),还表现采食量下降和不稳定,奶牛体况下降等症状.     

益生菌对奶牛亚急性瘤胃酸中毒的保护作用

亚急性瘤胃酸中毒对奶牛的生产性能有很大影响,使用益生菌来稳定奶牛分娩后-产奶过渡期瘤胃pH可以减轻这种代谢紊乱的症状。因此,本试验选择了体重(741±55)kg,产奶期在(212±19.5)d的奶牛4头,试验采用4×4拉丁方设计,共4种日粮:对照组饲喂基础日粮,处理1组为日粮添加0.5 g/d米曲菌,处理2组为日粮添加2.5 g/d米曲菌,处理3组为日粮添加2 g/d粪肠球菌和酿酒酵母菌的混合物。每组经过3 w的适应期、4 d酸中毒期以及3 d恢复期。结果显示:瘤胃最大pH范围在5.6～6.0,占比最高,与适应期和中毒期的结果相似。中毒期间,其他pH范围表现为显著差异(P <0.05)。中毒期,处理3组较对照组显著提高了瘤胃pH(P <0.05),同时处理3组瘤胃pH在5.6～6.0的占比也显著高于对照组(P <0.05)。日粮添加2.5 g/d米曲菌显著降低了产奶量(P <0.05)。奶牛遭受瘤胃酸中毒后,随着时间的推移,丙酸、丁酸和戊酸含量显著升高(P <0.05),而乙酸、异丁酸和异戊酸含量显著降低(P <0.05)。除了处理3组外,其他组瘤胃乳酸含量随时间的增加而升高(P <0.05)。饲喂12 d后,处理3组较对照组显著提高了乳酸含量(P <0.05)。瘤胃白球菌和大肠杆菌含量在饲喂2 h后显著升高(P <0.05),之后在6 h达到稳定。结论 :粪肠球菌和酿酒酵母菌复合物可以缓解奶牛亚急性瘤胃酸中毒的症状,米曲菌可以调控瘤胃pH,但高剂量米曲菌添加水平对瘤胃pH无显著影响。     

Signals for identifying cows at risk of subacute ruminal acidosis in dairy veterinary practice

Controlling rumen disorders is critical to ensure successful dairy herd health management. Lactation diets of dairy cows are commonly rich in concentrates and low in physically effective fibre. Feeding of these diets increases the risk of rumen disorders with far‐reaching consequences for cattle health, welfare and sustainability of dairy production. The term subacute ruminal acidosis or SARA is often used as a synonym for poor rumen health. Being subclinical, SARA lacks of clear symptoms and is therefore difficult to diagnose and to control in the practice. This review article summarises common and identifies new direct and indirect cow signals related to SARA. We have performed a scientific evaluation and interpretation of each of these cow signals by highlighting their advantages and disadvantages from the practitioner's point of view. The gold standard of SARA cow signals still remains direct measurement of ruminal pH. However, continuous pH monitoring is cost‐intensive and often biased by sensor drift. Single‐point ruminal pH measurements by oral stomach tubing or rumenocentesis have strong limitations. Therefore, there is a need for reliable and robust markers of SARA that are easily accessible and inexpensive. Such indirect parameters are the observation of chewing and feeding activities, as well as the monitoring of milk, faecal, urine and blood variables. Also, novel technologies that allow rapid and non‐invasive measurement of the rumen mucosa thickness and ruminal motility patterns might provide advantages in SARA diagnosis. Due to several constraints of these indirect diagnostic tools, such as limited specificity and sensitivity, we strongly recommend using a combination of the signals to reliably identify cows at risk of SARA in a dairy herd.     

亚急性瘤胃酸中毒耐受性不同的奶牛瘤胃上皮形态及功能差异研究

本试验旨在探究SARA（亚急性瘤胃酸中毒）耐受性不同奶牛的瘤胃上皮形态及其功能差异。选取12头装有永久性瘤胃瘘管的泌乳中期荷斯坦奶牛,饲喂精粗比为4∶6的日粮,并根据瘤胃pH值的高低,分为SARA易感组（SUS,n=4）和SARA耐受组（TOL,n=4）。瘤胃上皮形态及功能分析结果显示,与TOL组比较,SUS组奶牛瘤胃上皮的棘突层和基底层厚度明显增厚（P<0.05）,SUS组奶牛瘤胃上皮组织中参与挥发性脂肪酸（VFA）吸收的PAT1、MCT4和DRA基因表达量较TOL组显著下调（P<0.05）,而H+转运载体NHE1、NHE2、NHE3和调节胞内pH的vH+ATPase和Na+/K+ATPase的表达量显著升高（P<0.05）;对参与调控瘤胃VFA代谢的基因定量结果表明,SUS组PDHA1和SREBP2的表达量显著高于TOL组（P<0.05）,而HMGCL-2的表达量显著降低（P<0.05）;此外,SUS组CDK2、CDK6和Cyclin D1、Bad及Caspase-9等参与瘤胃上皮细胞增殖与凋亡的基因表达量显著高于TOL组（P<0.05）。结果说...     

奶牛亚急性瘤胃酸中毒的发生与危害

亚急性瘤胃酸中毒（SARA）是一个大多数牛场普遍存在的奶牛代谢性疾病。围产期、干物质采食量（DMI）过高、日粮配制差及采食模式变化过大等奶牛均易发生亚急性瘤胃酸中毒,继而造成干物质采食量下降、纤维素消化率降低、乳成分改变及引发腹泻等疾病。本文对奶牛亚急性瘤胃酸中毒的病因及危害等方面进行了简述。     

Pathophysiological evaluation of subacute ruminal acidosis (SARA) by continuous ruminal pH monitoring

Evaluation of the radio‐transmission pH‐measurement system for monitoring the ruminal pH and subacute ruminal acidosis (SARA) in cattle is described. This is done in order to reveal the possible application of this system for detection and pathophysiological research of SARA by continuous ruminal pH measurement. The possibility of using this system for assessment of the ruminal pH in SARA cattle, and the presence of negative correlation between the ruminal pH and ruminal temperature in heathy and SARA cattle were determined. In addition, the 16S rRNA gene pyrosequencing analysis showed that the ruminal microbial community was simpler in SARA cattle, and the bacterial numbers in SARA cattle were lower than those in healthy hay‐fed cattle. Concentrate feeding might have reduced the diversity of the ruminal microbial community. Changes in the ruminal microbial community of SARA cattle might be related to the changes in ruminal pH followed by the decrease in the number of some bacteria. Continuous monitoring of the ruminal pH using the radio‐transmission pH‐measurement system would be applied for detection and prevention of SARA in the field and pathophysiological research of SARA, including ruminal zymology and bacteriology, which have been determined previously by sampling of the ruminal fluid and measuring of ruminal pH.     

Induction of a transient acidosis in the rumen simulation technique

Feeding high concentrate diets to cattle results in an enhanced production of short‐chain fatty acids by the micro‐organisms in the rumen. Excessive fermentation might result in subclinical or clinical rumen acidosis, characterized by low pH, alterations in the microbial community and lactate production. Here, we provide an in vitro model of a severe rumen acidosis. A transient acidosis was induced in the rumen simulation technique by lowering bicarbonate, dihydrogen phosphate and hydrogen phosphate concentrations in the artificial saliva while providing a concentrate‐to‐forage ratio of 70:30. The experiment consisted of an equilibration period of 7 days, a first control period of 5 days, the acidosis period of 5 days and a second control period of 5 days. During acidosis induction, pH decreased stepwise until it ranged below 5.0 at the last day of acidosis (day 17). This was accompanied by an increase in lactate production reaching 11.3 mm at day 17. The daily production of acetate, propionate and butyrate was reduced at the end of the acidosis period. Gas production (methane and carbon dioxide) and NH₃‐N concentration reached a minimum 2 days after terminating the acidosis challenge. While the initial pH was already restored 1 day after acidosis, alterations in the mentioned fermentation parameters lasted longer. However, by the end of the experiment, all parameters had recovered. An acidosis‐induced alteration in the microbial community of bacteria and archaea was revealed by single‐strand conformation polymorphism. For bacteria, the pre‐acidotic community could be re‐established within 5 days, however, not for archaea. This study provides an in vitro model for a transient rumen acidosis including biochemical and microbial changes, which might be used for testing feeding strategies or feed additives influencing rumen acidosis.     

Subacute rumen acidosis in lactating cows: an investigation in intensive Italian dairy herds

Subacute rumen acidosis (SARA) represents one of the most important metabolic disorders in intensive dairy farms that affects rumen fermentations, animal welfare, productivity and farm profitability. The aim of the present study was to study the occurrence of SARA in intensive Italian dairy herds and to determine the relationship between diet composition, ruminal pH and short chain fatty acids (SCFA) concentration. Ten commercial dairy herds were investigated; twelve cows in each herd were selected randomly among animal without clinical signs of disease, with good body condition and between 5 and 60 day-in-milk (DIM), to perform rumenocentesis and obtain rumen fluid. Ruminal pH was determined immediately after sampling and concentration of SCFA in ruminal fluid was determined on samples after storage. An other objective of this research was to study in detail the effects of rumenocentesis on animal health: this study could confirm the extreme validity of this technique as ruminal sampling. Results were subject to anova and correlation analysis using SIGMA STAT 2.03. The results indicated the presence of SARA in three herds (more than 33% cows with rumen pH < 5.5), a critical situation (more than 33% cows with rumen pH < 5.8) in five farms and a normal rumen pH condition in two herds. In particular, dairy herds show on average SCFA concentration of 150, 145, 123 mmol/l for low pH, critical pH and normal pH herds respectively. There were not significant differences among diet composition even if herds with SARA showed a light discordance between initially chemistry composition and residual feed. In the affected herds it was not possible to understand the exact causes of SARA. Animal management seems to be one of the most important factors in developing SARA including total mixed ration preparation.     

亚急性瘤胃酸中毒对泌乳奶牛血浆生化指标及代谢组的影响研究

本试验旨在探究亚急性瘤胃酸中毒（subacute rumen acidosis, SARA）对泌乳奶牛血液生化指标和血浆代谢组的影响。试验选用8头装有永久性瘤胃瘘管的泌乳中期奶牛,随机分成对照组（CON）（n=4）和处理组（SARA）（n=4）,CON组与SARA组分别饲喂精粗比为4∶6和6∶4的全混合日粮,试验周期为3周。于试验期每周最后一天晨饲后0、2、4、6、8和12 h进行瘤胃pH的测定,同时在pH测定当天晨饲后6 h采集颈静脉血样,用于血液生化指标和代谢组的分析。结果表明,与CON组相比,SARA组的瘤胃pH显著降低（P=0.002）,两组干物质采食量没有显著差异（P=0.524）。血浆生化指标结果显示,与CON组比较,SARA组奶牛的β-羟丁酸浓度显著降低（P=0.007）,甘油三酯浓度显著升高（P=0.014）。采用液相-质谱（LC-MS）联用技术对血浆进行代谢组学分析,主成分分析（PCA）和偏最小二乘法分析（PLS-DA）结果显示,SARA组奶牛血浆代谢物组成较CON组发生明显变化,两组间共检测到26种差异代谢物（VIP>1 & FDR<0.05）,与CON组相比,SARA组奶牛血浆中的7-酮脱氧胆酸、脱氧胆酸、胆酸、12-酮脱氧胆酸、12（13）Ep-9-KODE、12,13-DHOME和L-天冬酰胺代谢物含量显著升高（FDR<0.05）,而十一烷二酸、十六烷二酸、9-HODE、血氧烷B3、PGE2、L-精氨酸、L-色氨酸、L-苏氨酸、异丁酰甘氨酸、异戊酰甘氨酸、马尿酸、4-羟基马尿酸和6-磷酸-2-脱氢-D-葡萄糖酸酯等代谢物含量显著降低（FDR<0.05）。综上,与CON组比较,SARA组奶牛的脂代谢、氨基酸代谢和糖代谢发生显著变化,这些物质可作为SARA潜在的生物标志物。     

Anti-lipopolysaccharide antibody administration mitigates ruminal lipopolysaccharide release and depression of ruminal pH during subacute ruminal acidosis challenge in Holstein bull cattle

The effects of anti-lipopolysaccharide (LPS) antibody on rumen fermentation and LPS activity were investigated during subacute ruminal acidosis (SARA) challenge. Eleven Holstein cattle (164 ± 14 kg) were used in a 3 × 3 Latin square design. Cattle were fed a roughage diet on days −11 to −1 (pre-challenge) and day 2 (post-challenge), and a high-grain diet on days 0 and 1 (SARA challenge). For 14 days, 0-, 2-, or 4-g of anti-LPS antibody was administered once daily through a rumen fistula. Ruminal pH was measured continuously, and rumen fluid and blood samples were collected on days −1, 0, 1, and 2. Significantly lower ruminal LPS activity on day 1 was observed in the 2- and 4-g groups than those in the 0-g group. In addition, significantly higher 1-hr mean ruminal pH on SARA challenge period (days 0 and 1) was identified in the 4-g group than in the 0-g group. However, rumen fermentation measurements (total volatile fatty acid [VFA], VFA components, NH₃-N and lactic acid) and peripheral blood metabolites (glucose, free fatty acid, beta-hydroxybutyrate, total cholesterol, blood urea nitrogen, aspartate aminotransferase and gamma-glutamyl transferase) were not different among the groups during the experimental periods. Therefore, anti-LPS antibody administration mitigates LPS release and pH depression without the depression of rumen fermentation and peripheral blood metabolites during SARA challenge in Holstein cattle.     

Effect of live yeast (Saccharomyces cerevisiae) supplementation on rumen fermentation and metabolic profile of dairy cows in early lactation

The study evaluated dietary supplementation with live yeast (LY) Saccharomyces cerevisiae (CNCM I‐4407, 10¹⁰ CFU/g, Actisaf; Phileo Lesaffre Animal Care, France) on rumen fermentation and serum metabolic profile in lactating dairy cows. Fifty Holstein cows received a total mixed ration with (Live Yeast Diet, LYD, n = 25) or without (Control Diet, CD, n = 25) 5 × 10¹⁰ CFU/cow/day of LY from 3 to 19 weeks of lactation. Rumen fermentation and serum metabolic profile were measured in eight cows per treatment at 3, 7, 11, 15, 19 weeks post‐partum. LYD showed an increased daily milk yield (+4%) over CD (p < 0.05). Mean rumen pH at 4 hr after morning meal was higher in LYD (6.59) than CD (6.32) (p < 0.01). Total volatile fatty acids (VFA) and acetate molar proportion were higher in LYD (114.24 mM; 25.04%) than CD (106.47 mM; 24.73%) (p < 0.05). Propionate and butyrate molar proportions, acetate to propionate ratio, ammonia levels did not differ between LYD and CD. Ruminal lactate was lower in LYD than CD (9.3 vs. 16.4 mM) (p < 0.001), with a 53% decrease in LYD. During peak lactation, LYD had lower serum NEFA (p < 0.05, 0.40 vs. 0.48 mM) and BHBA (p < 0.01, 0.47 vs. 0.58 mM) than CD, lower liver enzyme activities (AST 1.39 vs. 1.54 ukat/L) (p < 0.05). Serum glucose was higher in LYD at peak lactation (3.22 vs. 3.12 mM, and 3.32 vs. 3.16 mM respectively) (p < 0.05). The results confirmed a reducing effect of LY on lactate accumulation in rumen fluid, associated with an increase in rumen pH. Lower serum levels of lipomobilization markers, liver enzyme activities and higher glucose levels may suggest that live yeast slightly mitigated negative energy balance and had a certain liver protective effect.     

Responsive changes of rumen microbiome and metabolome in dairy cows with different susceptibility to subacute ruminal acidosis

Subacute ruminal acidosis(SARA)represents one of the most important digestive disorders in intensive dairy farms,and dairy cows are individually different in the severity of SARA risk.The objectives of the current study were to investigate differences in the ruminal bacterial community and metabolome in dairy cattle with different susceptibility to SARA.In the present study,12 cows were initially enrolled in the experiment.Based on average ruminal pH,4 cows with the lowest ruminal pH were assigned to the susceptible group(SUS,pH=5.76,n=4)and 4 cows with the highest ruminal pH assigned to the tolerant group(TOL,pH=6.10,n=4).Rumen contents from susceptible(SUS,n=4)and tolerant(TOL,n=4)dairy cows were collected through rumen fistula to systematically reveal the rumen microbial and metabolic alterations of dairy cows with different susceptibility to SARA using multi-omics approaches(16S and 18S rRNA gene sequencing and metabolome).The results showed that despite being fed the same diet,SUS cows had lower ruminal pH and higher concentrations of total volatile fatty acids(VFA)and propionate than TOL cows(P<0.05).No significant differences were observed in dry matter intake,milk yield,and other milk compositions between the SUS and TOL groups(P>0.05).The principal coordinates analysis based on the analysis of molecular variance indicated a significant difference in bacterial composition between the two groups(P=0.01).More specifically,the relative abundance of starch-degrading bacteria(Prevotella spp.)was greater(P<0.05),while the proportion of fiber-degrading bacteria(unclassified Ruminococcaceae spp.,Ruminococcus spp.,Papillibacter,and unclassified Family_-XIII)was lower in the rumen of SUS cows compared with TOL cows(P<0.05).Community analysis of protozoa showed that there were no significant differences in the diversity,richness,and community structure(P>0.05).Metabolomics analysis revealed that the concentrations of organic acids(such as lactic acid),biogenic amines(such as histamine),and bacterial degradation products(such as hypoxanthine)were significantly higher in the SUS group compared to the TOL group(P<0.05).These findings revealed that the higher proportion of starch-degrading bacteria/lower fiber-degrading bacteria in the rumen of SUS cows resulted in higher VFA-producing capacity,in particular propionate.This caused a disruption in metabolic homeostasis in the rumen which might be the reason for the higher susceptibility to SARA.Overall,these findings enhanced our understanding of the ruminal microbiome and metabolic changes in cows susceptible to SARA.     

Effects of Lonicera japonica extract supplementation on in vitro ruminal fermentation,methane emission,and microbial population

Lonicera japonica (LJ; honeysuckle) is used in traditional folk medicine in Korea and is a rich source of ascorbic acid and phenolic components that are reported to have antioxidant and antibiotic properties. We performed an in vitro experiment to assess the effects of LJ extracts (LJE) on ruminal fermentation. Timothy hay (0.3 g dry matter [DM]) was incubated with buffer, ruminal fluid, and 0%, 3%, 5%, 7%, and 9% LJE. Batch culture fermentation was conducted separately for 12, 24, and 48 hr to determine gas production (GP), ruminal fermentation characteristics, and microbial population characteristics. The effects on GP were generally similar to those on DM degradability, with a linear decrease observed at 9% extract at 24 hr. NH₃‐N showed a linear increase with increasing extract concentrations at 12 hr, whereas a decrease was observed at 24 hr. Extract supplementation decreased methane (CH₄) production at 12, 24, and 48 hr. In addition, the abundance of fibrolytic bacteria and ciliate‐associated methanogen was reduced at all concentrations of extracts. These results indicate that LJE have the potential to serve as a ruminal fermentation modifier to suppress CH₄ production with minimal effects on nutrient digestion in the rumen.     

Prevalence of VTEC O157 in dairy and veal herds and risk factors for veal herds

The aim of this study was to determine the herd prevalence of veal and dairy herds and to identify risk factors for VTEC O157 positive veal herds. The study was based on monitoring data from November 1996 through July 2005 of 1051 dairy herds and 930 veal herds. The herd level prevalence (95% CI) was 8.0% (6.4–9.6) for dairy herds and 12.6% (10.5–14.7) for veal herds. Within the population of veal herds, a prevalence of 39.8% (33.9–45.6) was found for pink veal herds (n = 269) and 1.5% (0.7–2.8) for white veal herds (n = 661).Multivariable logistic regression showed that the type of veal (pink vs. white; OR = 21.6; 95% CI: 10.4–45.0), ventilation (mechanical vs. natural; OR = 0.4; 95% CI: 0.2–0.8), time between arrival in the herd and sampling (3–5 months vs. 0–2 months: OR = 2.33; 95% CI: 1.1–5.1, ≥6 months vs. 0–2 months: OR = 4.11; CI: 1.9–8.9), other feed than the 7 most common (yes vs. no; OR = 2.1; 95% CI: 1.2–3.7) and at least one dog present in the stable (yes vs. no; OR = 2.6; 95% CI: 1.5–4.6) were significantly (P < 0.05) associated with the presence of VTEC O157. The large difference in the VTEC O157 prevalences for pink veal and white veal production might have been caused by a very different management of these type of herds. However, this could not be studied with the data collected.     

Changes in in vitro ruminal and post‐ruminal degradation of tropical tannin‐rich legumes due to varying levels of polyethylene glycol

We evaluated the effects of tannins from Flemingia macrophylla (CIAT 17403) and Calliandra calothyrsus (San Ramón CIAT 22310 and Patulul CIAT 22316) on in vitro ruminal and post‐ruminal dry matter and apparent protein degradation. For each tannin source (legumes), different dosages of polyethylene glycol (PEG) (8000 Da) in McDougall buffer were added to achieve ratios of 0:3, 1:3, 2:3 and 3:3 PEG:condensed tannin (CT). Ruminal fluid mixed with McDougall buffer (1:4) was added to tubes containing only legume foliage (control) or PEG‐treated legume foliage. For both Calliandra varieties, a higher ruminal dry matter degradation was observed at a PEG:CT ratio of 3:3. For F. macrophylla, no differences were found between 2:3 and 3:3 ratios (p > 0.05), indicating that a PEG:CT ratio of 2:3 might be enough to bind tannins. Increasing PEG:CT ratios increased apparent ruminal degraded protein and ammonia concentration (p < 0.0001) differing among species (species × ratio: p < 0.0001). The degradation of bypass crude protein (dBCP) was influenced by both legume type and PEG:CT ratio (p < 0.0001). For Patulul, as PEG:CT ratio increased, dBCP increased, but after tannin ratio of 2:3, there was not a significant increase, and for San Ramón, dBCP degradation was higher as PEG:CT ratio increased up to 2:3. For Flemingia, dBCP was higher than PEG:CT ratio of 0:3 but not different among 1:3, 2:3 or 3:3. Low concentration of CT (116 mg/g DM) increased the proportion of protein digested in the abomasum, but higher levels of CT (252 mg/g) clearly reduced the proportion of digested CP. For Flemingia, PEG:CT ratio of 2:3 is enough to inactivate tannins, while PEG:CT ratio of 3:3 was needed for Calliandra and consequently increased ruminal degradation of dry mater (rdDM), and crude protein (rdCP), total degradation of dry matter (tdDM), crude protein (tdCP) and ammonia levels.