The oral microbiome as a proxy for feed intake in dairy cattle.

Genetic material from rumen microorganisms can be found within the oral cavity, and hence there is potential in using the oral microbiome as a proxy of the ruminal microbiome. Feed intake (FI) influences the composition of rumen microbiota and might directly influence the oral microbiome in dairy cattle. Ruminal content samples (RS) from 29 cows were collected at the beginning of the study and also 42 d later (RS0 and RS42, respectively). Additionally, 18 oral samples were collected through buccal swabbing at d 42 (OS42) from randomly selected cows. Samples were used to characterize and compare the taxonomy and functionality of the oral microbiome using nanopore sequencing and to evaluate the feasibility of using the oral microbiome to estimate FI. Up to 186 taxonomical features were found differentially abundant (DA) between RS and OS42. Similar results were observed when comparing OS42 to RS collected on different days. Microorganisms associated with the liquid fraction of the rumen were less abundant in OS42 because these were probably swallowed after regurgitation. Up to 1,102 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were found to be DA between RS and OS42, and these results differed when comparing time of collection, but DA KEGG pathways were mainly associated with metabolism in both situations. Models based on the oral microbiome and rumen microbiome differed in their selection of microbial groups and biological pathways to predict FI. In the rumen, fiber-associated microorganisms are considered suitable indicators of FI. In contrast, biofilm formers like Gammaproteobacteria or Bacteroidia classes are deemed appropriate proxies for predicting FI from oral samples. Models from RS exhibited some predictive ability to estimate FI, but oral samples substantially outperformed them. The best lineal model to estimate FI was obtained with the relative abundance of taxonomical feature at genera level, achieving an average R2 = 0.88 within the training data, and a root mean square error of 3.46 ± 0.83 (±SD) kg of DM, as well as a Pearson correlation coefficient between observed and estimated FI of 0.48 ± 0.30 in the test data. The results from this study suggest that oral microbiome has potential to predict FI in dairy cattle, and it encourages validating this potential in other populations.

Benefits of barley straw as a forage for dairy calves before and after weaning.

The aim of this study was to assess the potential consequences on calf intake, performance, behavior, ruminal microbiome, and ruminal epithelium development of combining the inclusion of chopped barley straw and alfalfa hay during the pre- and postweaning periods keeping concentrate to forage ratio constant among dietary treatments. Forty-five Holstein calves (44 ± 5.7 kg of body weight [BW] and 3 ± 1.5 d of age) individually penned were blocked by BW and randomly assigned to a common pellet concentrate fed ad libitum along with one of following forage feeding strategies: barley straw before and after weaning (S-S), barley straw before and alfalfa hay after weaning (S-A), or alfalfa hay before and after weaning (A-A). All calves received the same milk replacer regimen. Forage was supplied in a separated bucket at the rate of 7.5% (preweaning) and 15% (postweaning) of total solid feed intake of the previous day. Feed intake and BW were recorded daily and weekly, respectively. Rumen samples were obtained via a stomach tube at 53, 66, and 87 d and were composite in 3 samples of 5 animals each for subsequent rumen microbiome analysis. A rumen epithelium sample was taken by endoscopy at 90 d to assess gene expression of OCLN, CLDN4, SLC9A1, SLC9A3, SLC16A1, SLC16A4, IL6, and TGFB1. Data were analyzed with a mixed-effects model accounting for the fixed effects of block, forage, week of study, and their interaction, and calf as a random effect. The type of forage fed did not affect concentrate feed, forage, or total DM intake before weaning. However, S-A and A-A calves consumed less concentrate feed and S-A calves grew at a lower rate after weaning than S-S calves. Expression of the gene coding for SLC16A1 in the rumen epithelium was greatest in S-S among treatments. Rumen microbiome did not differ among treatments, while the relative abundance of Acidaminococcus and Selenomas genera increased, while Alloprevotella, Bifidobaterium, Olsenella, and Succiclasticum genera decreased with age. In conclusion, feeding barley straw before and after weaning was more effective than feeding alfalfa hay in promoting concentrate feed intake after weaning and fostering an increase in the expression of SLC16A1 in the rumen epithelium.

Using compositional mixed-effects models to evaluate responses to amino acid supplementation in milk replacers for calves.

The consequences of supplementing Lys, Met, and Thr in milk replacers (MR) for calves have been widely studied, but scarce information exists about potential roles of other AA (whether essential or not). The effects on growth performance of supplementation of 4 different AA combinations in a mixed ration (25.4% crude protein and 20.3% fat) based on skim milk powder and whey protein concentrate were evaluated in 76 Holstein male calves (3 ± 1.7 d old). The 4 MR were as follows: CTRL with no AA supplementation; PG, supplying additional 0.3% Pro and 0.1% Gly; FY, supplying additional 0.2% Phe and 0.2% Tyr; and KMT, providing additional 0.62% Lys, 0.22% Met, and 0.61% Thr. All calves were fed the same milk allowance program and were weaned at 56 d of study. Concentrate intake was limited to minimize interference of potential differences in solid feed intake among treatments. Animals were weighed weekly, intakes recorded daily, and blood samples obtained at 2, 5, and 7 wk of study to determine serum urea and plasma AA concentrations. Plasma AA concentrations were explored using compositional data analysis, and their isometric log-ratio transformations were used to analyze their potential influence on ADG and serum urea concentration using a linear mixed-effects model. We detected no differences in calf performance and feed intake. Plasma relative concentration of the AA supplemented in the KMT and PG treatments increased in their respective treatments, and, in PG calves, a slight increase in the proportion of plasma Gly, Glu, and branched-chain AA was also observed. The proportions of plasma branched-chain AA, His, and Gln increased, and those of Thr, Arg, Lys, and Glu decreased with calves' age. A specific log-contrast balance formed by Arg, Thr, and Lys was found to be the main driver for lowering serum urea concentrations and increasing calf growth. The use of compositional mixed-effects models identified a cluster formed by the combination of Arg, Thr, and Lys, as a potential AA to optimize calf growth.

Piecewise modeling of the associations between dry period length and milk, fat, and protein yield changes in the subsequent lactation.

Our objective was to develop predictive models of 305-d mature-equivalent milk, fat, and protein yields in the subsequent lactation as continuous functions of the number of days dry (DD) in the current lactation. In this retrospective cohort study with field data, we obtained DHIA milk recording lactation records with the last DD in 2014 or 2015. Cows included had DD from 21 to 100 d. After editing, 1,030,141 records from cows in 7,044 herds remained. Three parity groups of adjacent (current, subsequent) lactations were constructed. We conducted all analyses by parity group and yield component. We first applied control models to pre-adjust the yields in the subsequent lactation for potentially confounding effects. Control models included the covariates mature-equivalent yield, days open, somatic cell score at 180 d pregnant, daily yield at 180 d pregnant, and a herd-season random effect, all observed in the current lactation. Days dry was not included. Second, we modeled residuals from control models with smooth piecewise regression models consisting of a simple linear, quadratic, and another simple linear equation depending on DD. Yield deviations were calculated as differences from predicted mature-equivalent yield at 50 DD. For validation, predictions of yield deviations from piecewise models by DD were compared with predictions from local regression for the DHIA field records and yield deviations reported in 38 experimental and field studies found in the literature. Control models reduced the average root mean squared prediction error by approximately 21%. Yield deviations were increasingly more negative for DD shorter than 50 d, indicating lower yields in the subsequent lactation. For short DD, the decrease in 305-d mature-equivalent milk yield ranged from 43 to 53 kg per DD. For mature-equivalent fat and protein yields, decreases were between 1.28 and 1.71 kg per DD, and 1.06 and 1.50 kg per DD, respectively. Yield deviations often were marginally positive and increasing for DD >50, so that the highest yield in the subsequent lactation was predicted for 100 DD. For long DD, the 305-d mature-equivalent milk yield increased at most 4.18 kg per DD. Patterns in deviations for fat and protein yield were similar to those for milk yield deviations. Predictions from piecewise models and local regressions were very similar, which supports the chosen functional form of the piecewise models. Yield deviations from field studies in the literature typically were decreasing when DD were longer, likely because of insufficient control for confounding effects. In conclusion, piecewise models of mature-equivalent milk, fat, and protein yield deviations as continuous functions of DD fit the observed data well and may be useful for decision support on the optimal dry period length for individual cows.

Evaluating the potential role of tryptophan in calf milk replacers to facilitate weaning.

Tryptophan is a precursor of serotonin, a neurotransmitter that participates in the control of the affective state of an animal. We hypothesized that Trp supplementation could help dairy calves to cope with weaning stress. Twenty-seven Holstein male calves (48 ± 0.8 d old; 82 ± 2.6 kg of body weight) were used to evaluate the effects of Trp supplementation at a rate of 4.5 g/d via milk replacer (MR) on performance and behavioral parameters around weaning. All calves received the same feeding program (6 L/d at 15% dry matter from d 1 to 7, 4 L/d at 15% dry matter from d 8 to 14, and 2 L/d at 15% dry matter in one feeding until d 21 of study) and were completely weaned 22 d after the beginning of the study (around 70 d of life). Calves were fed a starter feed (19.3% crude protein and 16.2% neutral detergent fiber, on a dry matter basis) and chopped straw ad libitum. Animals were weighed weekly, dry matter intakes were recorded daily, lying behavior was recorded using accelerometers throughout the study, and scan sampling was performed twice a week, 1 h after the morning feeding, to record behavioral activity (nonnutritive oral behaviors, suckling a neighbor calf, standing, resting, rumination, vocalizations, eating, and drinking). Tryptophan supplementation did not affect calf performance or concentrate and MR intake, but straw intake tended to be greater in nonsupplemented compared with Trp-supplemented calves (153 vs. 129 ± 9.0 g/d, respectively). Lying time, lying bouts, and lying duration decreased when changes in the MR feeding program occurred, independent of treatment. Similarly, differences in behavioral observations occurred along days of study, with no effect of Trp supplementation. The main changes observed in calf behavior were an increase in vocalizations and standing time 1 h after the morning feeding at weaning, but again these changes were independent of treatment. Parameters measured in serum and plasma indicated an increase in Trp, kynurenine, and the kynurenine/Trp ratio after feeding in the Trp calves. A tendency for lower plasma glucose concentration after feeding was observed in the Trp group. No changes in stress markers such as cortisol and haptoglobin in serum were detected. In conclusion, supplementing 4.5 g/d of Trp via MR between 48 and 62 d of life had no effect on performance or behavior in calves around weaning.

Short communication: Performance, intestinal permeability, and metabolic profile of calves fed a milk replacer supplemented with glutamic acid.

The objective of this study was to evaluate the potential benefits of supplementing glutamic acid in milk replacers (MR) with respect to calf performance, intestinal permeability, and metabolism. Sixty Holstein male calves (3 ± 1.3 d old and 45 ± 5.9 kg body weight) were individually housed and fed a control MR without AA supplementation (24.8% crude protein and 19.1% fat, dry matter basis), or MR supplemented with 0.3% glutamic acid (25.1% crude protein and 20.3% fat, dry matter basis). Animals followed the same MR feeding program and were weaned at 56 d of the study. The amount of starter concentrate offered was restricted to limit the effect of concentrate intake on calf metabolism. Individual daily consumption and weekly body weight were measured, and 4 h after the morning feeding, blood samples were obtained at 14 and 35 d to determine general biochemical parameters and plasma AA concentrations. On d 10 of the study, we conducted an intestinal permeability test by including 21 g of lactulose and 4.2 g of d-mannitol as markers in the MR. We found no differences in calf performance or in intestinal permeability (measured as lactulose:mannitol ratio). Serum glucose concentration was greater in unsupplemented calves than in Glu-supplemented calves. At 14 d, the proportion of plasma Leu was greater in Glu-supplemented calves; the proportion of Ile tended to be greater in Glu-supplemented calves; and the proportion of Met tended to be greater in unsupplemented calves. We observed no other differences. Small changes occurred in AA metabolism when supplementing calf MR with 0.3% glutamic acid, without leading to improvements in calf performance or changes in intestinal permeability.

Changes in the rumen and colon microbiota and effects of live yeast dietary supplementation during the transition from the dry period to lactation of dairy cows.

The first objective of this study was to evaluate the dynamics and their potential association with animal performance of the microbiota in both the rumen and colon of dairy cows as they move from a nonlactation to a lactation ration. The second objective was to assess the potential effects on the microbiota of live yeast supplementation. Twenty-one Holstein cows were split in 2 treatments consisting of 1 × 1010 cfu/d of live yeast (LY; n = 10) or no supplementation (control; n = 11) starting 21 d before until 21 d after calving. At 14 d before and 7 and 21 d after calving, samples of rumen and colon digesta were obtained from each cow using an endoscope. Total DNA was extracted and submitted to high-throughput sequencing. Shannon diversity index, in both the rumen and colon, was unaffected by LY; however, in the rumen it was lowest 7 d after calving and returned to precalving values at 21 d in milk, whereas in the colon it was greatest 14 d before calving but decreased after calving. In the rumen, LY supplementation increased the relative abundance (RA) of Bacteroidales (group UCG-001), Lachnospiracea (groups UCG-002 and UCG-006), and Flexilinea 14 d before calving, and increased RA of Streptococcus 21 d after calving compared with control cows. However, changes in the ruminal microbiota were more drastic across days relative to calving than as influenced by the dietary treatment, and the effect of LY in the colon was milder than in the rumen. The ruminal RA of several genera was associated with postcalving DMI, and that of Gastranaerophilales was the only order positively associated with milk yield. Several genera were positively correlated with feed efficiency, with Clostridiales (unclassified) being the only genus negatively associated with feed efficiency. In the colon, Prevotellaceae (group Ga6A1) was the only genus positively associated with feed efficiency. The ruminal RA of Prevotella 7 and Ruminobacter 14 d precalving was negatively correlated with dry matter intake and milk yield postcalving. The RA of Parabacteroides in the colon 14 d before calving was negatively correlated with milk yield, whereas the RA of Eggerthellaceae (unclassified) and Erysipelotrichaceae (groups c and unclassified) were positively correlated with feed efficiency. Interestingly, LY supplementation doubled the RA of Eggerthellaceae (unclassified) in the colon. It is concluded that microbial diversity in the rumen experiences a transient reduction after calving, whereas in the colon, the reduction is maintained at least until 21 d in milk. Most of the effects of LY on rumen microbiota were observed before calving, whereas in the colon, LY effects were more moderate but consistent and independent of the stage of production. The microbial community of the rumen after calving is more associated with feed intake, milk yield, and feed efficiency than that of the colon. However, the colon microbiota before calving is more associated with feed efficiency after calving than that of the rumen.

Effects of oral administration of acidogenic boluses at dry-off on performance and behavior of dairy cattle.

The aim of this study was to evaluate the potential of oral acidogenic mineral boluses (196 g) containing anionic salts to facilitate the transition from lactation to the dry stage by inducing a mild and temporary metabolic acidosis at dry-off. In experiment 1, 84 lactating cows were randomly allocated to 1 of 3 treatment groups consisting of an oral administration of 0, 1, or 2 boluses 5 d before dry-off to evaluate the effects on milk production. In experiment 2, 16 lactating cows were involved in a crossover study to evaluate the effects of the administration of 2 boluses on milk production, feed intake, and urine pH. In experiment 3, 152 lactating cows were allocated to 1 of 2 treatments (control: no treatment; bolus: 2 oral boluses the day before last milking) to evaluate udder pressure, incidence of milk leakage, and lying behavior during the first days following dry-off. Also, milk yield in the subsequent lactation for all enrolled cows was recorded during the first 60 DIM. In experiment 1, cows receiving 2 boluses had the greatest reduction in milk production (-2.56 kg/d of milk) compared with those receiving 1 bolus or no treatment (-1.15 and -0.23 kg/d, respectively) the second day after bolus application. In experiment 2, the application of oral boluses decreased feed intake of cows during the first 3 d following treatment, and milk production was reduced on d 2 and 3 after bolus application. Reduced urine pH at 8 and 24 h after treatment was observed in bolus cows compared with control cows. In experiment 3, bolus cows had lower udder pressure after drying off, but incidence of milk leakage did not differ between treatments. Bolus cows had an additional 85 min of lying time in the 24 h following dry-off. Serum P and ß-OH-butyrate concentrations were lower in bolus cows than in control cows after dry-off, but no other differences in blood parameters between treatments were observed. Also, no differences in milk yield in the subsequent lactation were observed between treatments. It is concluded that oral bolus application diminishes feed intake and milk production, and, if applied at dry-off, it decreases udder pressure and increases lying time during the first 24 h after dry-off.

Effects of fat inclusion in starter feeds for dairy calves by mixing increasing levels of a high-fat extruded pellet with a conventional highly fermentable pellet.

The objective of this study was to evaluate the effect of inclusion of an extruded high-fat pellet mixed with a conventional pelleted calf starter on energy intake and performance around weaning in calves. To this end, 75 female Holstein newborn calves (41.0 ± 4.98 kg) were randomly assigned to 1 of 5 iso-nitrogenous solid feed treatments consisting of 4 levels of fat inclusion by mixing a low-fat highly fermentable control pellet with 3 different levels of inclusion of an extruded high-fat pellet [control (100:0), 90:10, 80:20, and 70:30], and a high-fat single pellet (HFSP). The HFSP was equivalent iso-energetic and iso-nitrogenous, although it had almost 1 percentage point difference in fat relative to the 80:20 treatment, to contrast the effect of the dual-component pellet mixture. The extruded high-fat starter feed contained a high proportion of fat (38%), mainly from hydrogenated palm fatty acids. Calves were offered a milk replacer up to 900 g/d, and then pre-weaned at 49 d of age by halving milk allowance until 56 d when calves were weaned. Calves had ad libitum access to the starter diets, chopped straw, and water. Individual milk replacer and starter intakes were recorded daily and BW was determined weekly. A glucose tolerance test was performed at 49 and 84 d of age to evaluate blood glucose homeostasis. Apparent total-tract digestibility was determined from 70 to 75 d of age. Calves on the 90:10 treatment had greatest starter feed intake mainly due to a marked increase in solid feed intake around weaning. Metabolizable energy intake was increased when the extruded pellet was included in the starter. No differences were present in digestibility of ether extract among solid feed treatments. The area under the curve of blood glucose concentration after the glucose tolerance test was greatest in 80:20; intermediate in 70:30, HFSP, and control; and lowest in 90:10 calves. No differences were observed for insulin or other parameters related to blood glucose homeostasis. Delivering dietary fat by mixing an extruded high-fat pellet with a conventional highly fermentable pellet to reach a total fat content of 7% results in increased starter intake, energy intake, and body weight gain until 84 d of age compared with a conventional low-fat pellet, or a single pellet with increased fat content.

Changes in gene expression in the rumen and colon epithelia during the dry period through lactation of dairy cows and effects of live yeast supplementation.

The objectives of this study were (1) to use endoscopy to collect biopsies from the rumen and colon epithelia to describe changes in gene expression in these 2 tissues as cows move from a dry to a lactation ration and (2) to evaluate the potential influence that supplementation of live yeast could exert on these 2 epithelia. Twenty-one Holstein cows were split into 2 treatments and received either 300 g/d of corn containing 1 × 1010 cfu/d of live yeast (LY; n = 10) or 300 g/d of corn with no supplementation (control; n = 11) starting 21 ± 2.6 d (average ± SD) before until 21 d after calving. At 14 ± 2.6 d before the expected calving date, and exactly at 7 and 21 d after calving, rumen and colon biopsies were obtained from each cow using an endoscope. Total RNA was extracted from rumen and colon tissues, and the expression of IL10, TNFA, TLR4, IL1B, PCNA, MKI67, SGLT1, BAX, CASP3, OCLN, CLDN4, HSPA1A, HSPB1, DEFB1, and MCT1 (the latter only in rumen samples) was quantified by quantitative PCR. Overall, fluctuations in expression of the selected genes in the colon between the 2 stages of production and the 2 treatments were smaller than those found in the rumen. In the rumen epithelium, expression of TLR4 and DEFB1 was greatest before calving, with LY cows having a greater expression of TLR4 than control cows. Similarly, expression of IL10 was greatest in LY cows before calving. Expression of TNFA in the rumen epithelium of control cows was lowest at 21 DIM but in LY cows was kept steady among production stages. The expression of PCNA and MKI67 in the rumen epithelium was greatest at 7 DIM, indicating a high proliferation rate of this epithelium after calving. In the colon mucosa, expression of TLR4 and DEFB1 was greater than in the rumen, and DEFB1 expression was greater in LY cows than in control cows. The use of an endoscope allowed us to study the dynamics of rumen epithelium adaptation to increased supply of concentrate after calving, consisting of increased epithelia remodeling, reduction of the TLR4, and increased IL10 expression. Furthermore, the rumen epithelium of dry cows responded rapidly to live yeast, with changes in the expression of genes involved in the immune response becoming evident after 7 d of exposure to yeast. The expression of genes related to the immune response (mainly TLR4 and DEFB1) in the colon mucosa was greater than in the rumen, and the expression of DEFB1 was further stimulated by live yeast. It is concluded that the use of an endoscope allows the study of gene expression patterns in the rumen and hindgut epithelia. We report marked changes in the rumen wall and more modest changes in the colon when transitioning from a dry to a lactation ration. Furthermore, supplementation of live yeast fostered and increased expression of genes regulating inflammation and epithelial barrier in the rumen, and in the colon it increased the expression of DFEB1 coding for an antimicrobial peptide.

NSD1 duplication in Silver-Russell syndrome (SRS): molecular karyotyping in patients with SRS features.

Silver-Russell syndrome (SRS) is a growth retardation syndrome characterized by intrauterine and postnatal growth retardation, relative macrocephaly and protruding forehead, body asymmetry and feeding difficulties. Nearly 50% of cases show a hypomethylation in 11p15.5, in 10% maternal uniparental disomy of chromosome 7 is present. A significant number of patients with SRS features also exhibit chromosomal aberrations. We analyzed 43 individuals referred for SRS genetic testing by molecular karyotyping. Pathogenic variants could be detected in five of them, including a NSD1 duplication in 5q35 and a 14q32 microdeletion. NSD1 deletions are detectable in overgrowth disorders (Sotos syndrome and Beckwith-Wiedemann syndrome), whereas NSD1 duplications are associated with growth retardation. The 14q32 deletion is typically associated with Temple syndrome (TS14), but the identification of a patient in our cohort reflects the clinical overlap between TS14 and SRS. As determination of molecular subtypes is the basis for a directed counseling and therapy, the identification of pathogenic variants in >10% of the total cohort of patients referred for SRS testing and in >16% of characteristic individuals with the characteristic SRS phenotype confirms the need to apply molecular karyotyping in this cohort.

Associations between subclinical hypocalcemia and postparturient diseases in dairy cows.

Dairy cows suffer blood Ca losses as lactation begins and might be affected by hypocalcemia in its clinical (total serum Ca concentration <1.50 mM) or subclinical form (total serum Ca concentration ≤2.14 mM). Several studies have suggested that hypocalcemia is associated with different health problems of the cow but results from different studies are not consistent. The objective of this study was to assess potential associations between subclinical hypocalcemia (SCHC) and displaced abomasum, intramammary infections, metritis, retained placenta, and ketosis. Also, the associations between SCHC and milk yield and reproductive function were evaluated. After discarding cows (32) with clinical hypocalcemia, a total of 764 cows from 6 different commercial farms were enrolled in this study. Blood samples were collected at 24 to 48 h postcalving and analyzed for total Ca concentration. Odds ratios of the different afflictions potentially associated with SCHC were calculated. Seventy-eight percent of the analyzed cows incurred SCHC. The occurrence of displaced abomasum, ketosis, retained placenta, and metritis was 3.7, 5.5, 3.4, and 4.3 times more likely, respectively, in cows that had SCHC than in cows with normocalcemia. Furthermore, the risk of incurring retained placenta or metritis increased in multiparous cows as serum Ca concentrations decreased compared with that in primiparous cows. Normocalcemic cows, independent of parity, were more likely to show their first estrus sooner after calving than SCHC cows, but no correlation was found between SCHC and other reproductive parameters. Different serum Ca concentration cutoffs were identified for several postpartum afflictions (≤1.93, ≤2.05, ≤2.05, and ≤2.10 mM for ketosis, retained placenta, metritis, and displaced abomasum, respectively). In conclusion, SCHC, defined as serum Ca ≤2.14 mM, is a frequent illness affecting the majority of the dairy cows with important repercussions on health. However, if SCHC were to be used to predict postpartum disease, different serum Ca cutoff points are likely to be needed because best predictive cutoff values varied among postpartum ketosis, displaced abomasum, retained placenta, and metritis.

Feeding of waste milk to Holstein calves affects antimicrobial resistance of Escherichia coli and Pasteurella multocida isolated from fecal and nasal swabs.

The use of milk containing antimicrobial residues in calf feeding programs has been shown to select for resistant fecal Escherichia coli in dairy calves. However, information is scarce about the effects of feeding calves waste milk (WM) on the prevalence of multidrug-resistant bacteria. The objective of this study was to determine the antimicrobial resistance patterns of fecal E. coli and nasal Pasteurella multocida isolates from calves fed either milk replacer (MR) or WM in 8 commercial dairy farms (4 farms per feeding program). Fecal and nasal swabs were collected from 20 ± 5 dairy calves at 42 ± 3.2 d of age, and from 10 of these at approximately 1 yr of age in each study farm to isolate the targeted bacteria. Furthermore, resistance of E. coli isolates from calf-environment and from 5 calves at birth and their dams was also evaluated in each study farm. Resistances were tested against the following antimicrobial agents: amoxicillin-clavulanic acid, ceftiofur, colistin, doxycycline (DO), enrofloxacin (ENR), erythromycin, florfenicol, imipenem, and streptomycin. A greater number of fecal E. coli resistant to ENR, florfenicol, and streptomycin and more multidrug-resistant E. coli phenotypes were isolated in feces of calves fed WM than in those fed MR. However, the prevalence of fecal-resistant E. coli was also influenced by calf age, as it increased from birth to 6 wk of age for ENR and DO and decreased from 6 wk to 1 yr of age for DO regardless of the feeding program. From nasal samples, an increase in the prevalence of colistin-resistant P. multocida was observed in calves fed WM compared with those fed MR. The resistance patterns of E. coli isolates from calves and their dams tended to differ, whereas similar resistance profiles among E. coli isolates from farm environment and calves were observed. The findings of this study suggest that feeding calves WM fosters the presence of resistant bacteria in the lower gut and respiratory tracts of dairy calves.

Effects of feeding pasteurized waste milk to dairy calves on phenotypes and genotypes of antimicrobial resistance in fecal Escherichia coli isolates before and after weaning.

The aim of this study was to evaluate the effects of feeding pasteurized waste milk (pWM) to calves on antimicrobial resistance of fecal Escherichia coli at both phenotypic and genotypic levels. Fifty-two Holstein female calves (3 ± 1.3 d of age) were fed 1 of the 2 different types of milk: milk replacer (MR) without antimicrobials or pWM with ß-lactam residues until weaning at 49 d of age. Fecal swabs of all calves were obtained on d 0, 35, and 56 of the study and 3 E. coli isolates per sample were studied. Phenotypic resistance was tested by the disk diffusion method against a panel of 12 antimicrobials. A total of 13 resistance genes consisting of ß-lactam, sulfonamide, tetracycline, and aminoglycoside families were examined by PCR. Feeding pWM to calves increased the presence of phenotypic resistance to ampicillin, cephalotin, ceftiofur, and florfenicol in fecal E. coli compared with MR-fed calves. However, the presence of resistance to sulfonamides, tetracyclines, and aminoglycosides was common in dairy calves independent of their milk-feeding source, suggesting other factors apart from the feeding source are involved in the emergence of antimicrobial resistance.

[Nonthrombotic pulmonary embolisms]. / Nichtthrombotische Lungenembolien.

The term nonthrombotic pulmonary embolism (NTPE) is defined as embolization of pulmonary arteries caused by foreign bodies (e. g. detached catheter fragments), biological substances (e. g. septic thrombus) or exogenous substances (e. g. gas). The frequency of NTPE is underestimated. Symptoms can cover the spectrum from undetectable to sudden death. In addition to mechanical obstruction of the pulmonary arteries, some NTPEs trigger an inflammatory cascade that causes deterioration of vascular, pulmonary and cardiac function. Radiological imaging in combination with the medical history of patients is sufficient to identify most NTPEs with certainty. The aim of this article is to make readers aware of the symptoms, frequency, relevance, classification, pathophysiology, laboratory findings and radiological findings of the most frequent forms of NTPE. The spectrum of forms presented here includes pulmonary embolisms due to foreign bodies (intravascular, intracorporeal and extracorporeal), amniotic fluid, endogenous tissue, fat, tumors, septic thrombi, hydatids, cement, metallic mercury, gas, silicone and particles.

[Clinically relevant incidental cardiovascular findings in CT examinations]. / Klinisch relevante kardiovaskuläre Zufallsbefunde bei CT­Untersuchungen.

BACKGROUND AND METHOD: Incidental cardiovascular findings are a frequent phenomenon in computed tomography (CT) examinations. As the result of a dedicated PubMed search this article gives a systemic overview of the current literature on the most important incidental cardiovascular findings, their prevalence and clinical relevance. RESULTS: The majority of incidental cardiovascular findings are of only low clinical relevance; however, highly relevant incidental findings, such as aortic aneurysms, thromboses and thromboembolic events can also occasionally be found, especially in oncology patients. CONCLUSION: The scans from every CT examination should also be investigated for incidental findings as they can be of decisive importance for the further clinical management of patients, depending on their clinical relevance.

Cryopreservation of Lilium martagon l. meristems by droplet-vitrification and evaluation of their physiological stability.

BACKGROUND: The aim of the present study was to compare different strategies for cryopreservation of martagon lily meristems and to evaluate the physiological status of the regenerants. MATERIALS AND METHODS: The bulblets were stored at 5 degree C or 20 degree C and pretreated with 3% or 6% sucrose prior to droplet-vitrification. The meristems were then assessed for their survival and regeneration. Their photochemical activity was investigated using a Photosynthesis Yield Analyzer MINI PAM 2000 Portable Chlorophyll Fluorometer and their photosynthesis oxygen production was evaluated with a Plant Vital 5030 device. RESULTS: The plant material stored at 5 degree C on medium containing 3% sucrose exhibited lower survival (40.8%) and regeneration (75%) of meristems following cryopreservation compared with material stored at 20 degree C on medium containing 3% sucrose, for which survival was 65% and regeneration 87%. Treatment of lily meristems for 30 min with PVS2 yielded high survival and regeneration. The implemented cryopreservation protocol did not induce any physiological changes in regenerants. Chlorophyll fluorescence (Fv/Fm) was 0.822 for cryopreserved samples (+LN) and 0.824 for non-cryopreserved ones (-LN). Photosynthetic oxygen production (KphA) was 1.531 (+LN) and 1.410 (-LN). CONCLUSION: Droplet-vitrification seems to be an effective method for cryopreservation of martagon lily meristems with the aim of its ex situ protection.

The importance of calf sensory and physical preferences for starter concentrates during pre- and postweaning periods.

We performed 3 studies to evaluate the effects of feed sensory and form preferences in young calves on performance and rumen fermentation dynamics. In experiment 1, starter feeds containing wheat and soybean meal; wheat and canola meal; and oats and soybean meal were evaluated in 63 calves (9±0.9 d old). In experiment 2, 37 crossbreed female calves were used from 4 to 45 d of age (weaning) in a cafeteria study consisting of 4 different presentations of the same starter feed: meal, pellet, pellet mixed with whole-cereal grains (WHG), and pellet mixed with steamed-rolled cereal grains (SRG). In experiment 3, 63 Holstein male calves (10±1.03 d old) were randomly distributed to 2 treatments that consisted of feeding a pellet concentrate mixed with whole corn and barely grains (WHG) or the same pellet concentrate mixed with steamed-rolled corn and barley grains (SRG). In experiment 1, animals in all 3 treatments had similar intake and performance, and we found no differences in rumen fermentation parameters. In experiment 2, during the first week of study, calves had a greater preference for WHG; after the first week, calves had a greater preference for SRG. In experiment 3, starter concentrate intake was greater in WHG than in SRG concentrates between wk 5 and weaning. However, we observed no differences in growth or gain-to-feed ratio. Calves offered WHG concentrates had greater rumen pH and tended to have lower total rumen volatile fatty acid concentrations than those offered SRG concentrates. We concluded that preweaned calves preferred concentrates based on pellets mixed with steamed-rolled grains. When calves could not choose their starter feed, pellets mixed with steamed-rolled grains reduced concentrate intake and rumen pH compared to pellets mixed with whole grains, but performance was not impaired. Formulating starter concentrates according to calves' sensory and physical preferences had little effect on performance.

Is calcitonin an active hormone in the onset and prevention of hypocalcemia in dairy cattle?

The objective of this study was to assess the potential importance of calcitonin (CALC) in the onset of subclinical hypocalcemia (experiment 1) and in the physiological mechanisms underlying the prevention of bovine hypocalcemia under metabolic acidosis (experiments 2 and 3). In experiment 1, 15 Holstein cows naturally incurring subclinical hypocalcemia during the first 5d postpartum were classified as low subclinical hypocalcemia (LSH) when blood Ca concentrations were between 7.5 and 8.5mg/dL, or as high subclinical hypocalcemia (HSH) when blood Ca concentrations were between 6.0 and 7.6 mg/dL. Blood samples were taken daily from d -5 to 5 relative to parturition to determine concentrations of parathyroid hormone (PTH), CALC, and 1,25(OH)2D3. In experiment 2, 24 Holstein bulls (497 ± 69 kg of body weight and 342 ± 10.5d of age) were assigned to 2 treatments (metabolic acidosis or control). Metabolic acidosis was induced by an oral administration of ammonium chloride (2.5 mEq/d) during 10 d, and animals were slaughtered thereafter. Blood samples were collected before slaughter to determine CALC, PTH, 1,25(OH)2D3, and samples of urine, kidney, parathyroid, and thyroid glands were obtained immediately after slaughter to determine expression of several genes in these tissues. Last, in experiment 3, we tested the activity of CALC under metabolic acidosis in vitro using breast cancer cell (T47D) cultures. Although PTH tended to be greater in HSH than in LSH, the levels of 1,25(OH)2D3 were lower in HSH cows (experiment 1). Blood CALC concentration was not affected by the severity of subclinical hypocalcemia, but it was influenced by days from calving (experiment 1). The expression of PTH receptor (PTHR) in the kidney was increased under metabolic acidosis (experiment 2). Furthermore, the activity of CALC was impaired under acidic blood pH (experiment 3). In conclusion, the CALC rise in HSH cows after calving impaired the recovery of blood Ca concentrations because the PTHR response was not sufficient to activate 1,25(OH)2D3 and compensate for the CALC effect. Metabolic acidosis prevents hypocalcemia because the expression of PTHR is upregulated in the kidney, resulting in an increased PTH activity and a subsequent increase in 1,25(OH)2D3 serum concentrations. Moreover, an impairment of CALC activity at low pH enhances the hypercalcemic role of PTH.

Invited review: Transitioning from milk to solid feed in dairy heifers.

Calves are born with a physically and metabolically underdeveloped rumen and initially rely on milk to meet nutrient demands for maintenance and growth. Initiation of solid feed consumption, acquisition of anaerobic microbes, establishment of rumen fermentation, expansion of rumen in volume, differentiation and growth of papillae, development of absorption and metabolic pathways, maturation of salivary apparatus and development of rumination behavior are all needed as the calf shifts from dependence on milk to solid feed. In nature and some production systems (e.g., most beef calves), young ruminants obtain nutrients from milk and fresh forages. In intensive dairying, calves are typically fed restricted amounts of milk and weaned onto starter feeds. Here we review the empirical work on the role of feeding and management during the transition from milk to solid feed in establishing the rumen ecosystem, rumen fermentation, rumen development, rumination behavior, and growth of dairy calves. In recent years, several studies have illustrated the benefits of feeding more milk and group rearing of dairy calves to take advantage of social facilitation (e.g., housing with peers or dam), and this review also examines the role of solid feed on rumen development and growth of calves fed large quantities of milk and reared under different housing situations. We conclude that the provision of high-starch and low-fiber starter feeds may negatively affect rumen development and that forage supplementation is beneficial for promoting development of the gut and rumination behavior in young calves. It is important to note that both the physical form of starter diets and their nutritional composition affect various aspects of development in calves. Further research is warranted to identify an optimal balance between physically effective fiber and readily degradable carbohydrates in starter diets to support development of a healthy gut and rumen, rumination behavior, and growth in young calves.