Immune-stimulatory effects of a bacteria-based probiotic on peripheral leukocyte subpopulations and cytokine mRNA expression levels in scouring holstein calves

Interactions between rumen epithelium-associated microbiota and host immunological and metabolic adaptations in response to different milk replacer feeding intensities in dairy calves

The milk replacer feeding regime in dairy calves has a great impact on metabolic and immunological functioning and affects animal welfare and lifetime performance. The feeding regime influences the rumen microbial composition, and epithelium-associated microbes may interact with the immune system of the host. We examined the correlations between blood leukocyte counts and the rumen epithelium-associated microbiome in dairy calves fed 2 different milk replacer feeding intensities and if these factors related to metabolic traits. Fourteen newborn female dairy calves were allocated to a group receiving either 10% (n = 7) or 20% (n = 7) milk replacer of their body weight (on average 41 kg) and provided ad libitum access to grass hay and concentrate pellets. At 3 weeks of life, all calves were fitted with a rumen cannula. Calves were weaned at 12 weeks of life and received a total mixed ration for ad libitum intake. Pre- (8-10 weeks of life) and post-weaning (21-23 weeks of life), methane production was measured in respiration chambers, and rumen epithelium and blood were sampled for 16S rRNA sequencing and leukocyte analyses, respectively. Pre-weaning, the reduced milk replacer feeding intensity was accompanied with higher concentrate intake but lower growth performance (P < 0.001), a higher abundance of amylolytic and lower abundance of cellulolytic epimural microbes. The group fed a low milk replacer intensity had also greater portions of monocytes (P = 0.031), CD8+ (P < 0.001), and CD14+ (P = 0.044) leukocytes, suggesting elevated inflammatory conditions. Correlations between CD8+ T cells and rumen methanogens, Ruminococcaceae, and Lachnospiraceae were recorded, but these were not consistent throughout maturation. Post-weaning, differences in feed intake and rumen microbial composition converged among milk replacer groups, while differences in growth performance (P = 0.040) and CD8+ cells (P < 0.001) were still present. In conclusion, a reduced milk replacer feeding intensity in dairy calves compromised growth performance and immunity and this effect persisted in the long-term. Significant correlations between the proportion of leukocytes and distinct epimural microbe taxa indicated an interplay between rumen epimural colonization and immune functioning of the host. However, further research is required addressing this interplay between rumen epimural microbes and immune functioning in dairy calves.

Effects of supplementing direct-fed microbials on health and growth of preweaning Gyr × Holstein dairy calves

This study aimed to evaluate the effects of direct-fed microbials (DFM) on health and growth responses of preweaning Bos indicus × Bos taurus (Gyr × Holstein) crossbred calves. Ninety newborn heifer calves (initial BW of 35 ± 4.0 kg) were used. At birth, calves were ranked by initial BW and parity of the dam and assigned to: (1) whole milk without DFM supplementation (CON; n = 30), (2) whole milk with the addition of 1.0 g/calf per day of a Bacillus-based DFM (BAC; n = 30), or (3) whole milk with the addition of 1.0 g/calf per day of BAC and 1.2 g/calf per day of Enterococcus faecium 669 (MIX; n = 30). Milk was fed individually during the study (77 d), and the BAC and MIX treatments were offered daily throughout the 77-d preweaning period. All calves were offered a starter supplement and corn silage starting on d 1 and 60 of age, respectively. Milk and starter supplement intake were evaluated daily, and BW was recorded on d 0 and at weaning (d 77). Diarrhea and pneumonia were assessed daily, and fecal samples were collected on d 0, 7, 14, 21, and at weaning (d 77) for assessment of the presence of bacterial and protozoal pathogens via qPCR. All data were analyzed using SAS (v. 9.4) with calf as the experimental unit and using single-df orthogonal contrasts (BAC + MIX vs. CON; BAC vs. MIX). Daily feeding of DFM, regardless of type, improved weaning BW. Odds ratio for occurrence of pneumonia was lower for DFM-supplemented calves, but its occurrence did not differ between BAC and MIX calves. No Salmonella spp. or Escherichia coli F41 were detected in any of the calves. The proportion of calves positive for E. coli F17 was greater for DFM calves on d 7 (92% and 96% vs. 81% for BAC, MIX, and CON, respectively), on d 21 (13% and 26% vs. 7% for BAC, MIX, and CON, respectively), and at weaning (48% and 35% vs. 22% for BAC, MIX, and CON, respectively). For Clostridium difficile, more DFM calves were positive on d 7 (65% and 30% vs. 35% for BAC, MIX, and CON, respectively) and 14 (20% and 28% vs. 7% for BAC, MIX, and CON, respectively), but proportion of positive calves was also greater for BAC versus MIX on d 7. More CON calves were positive for Clostridium perfringens on d 14 (14% vs. 3% and 8% for CON, BAC, and MIX, respectively) compared with DFM-fed calves. Incidence of calves positive for C. perfringens was greater in BAC than MIX on d 7 (50% vs. 18%), and greater for MIX than BAC at weaning (9% vs. 0%). For protozoa occurrence, a lower proportion of DFM calves were positive for Cryptosporidium spp. on d 7 (58% and 48% vs. 76% for BAC, MIX, and CON, respectively), but opposite results were observed on d 21 for Cryptosporidium spp. (3% and 11% vs. 0% for BAC, MIX, and CON, respectively) and Eimeria spp. on d 14 (7% and 8% vs. 0% for BAC, MIX, and CON, respectively) and 21 (50% and 59% vs. 38% for BAC, MIX, and CON, respectively). In summary, DFM feeding alleviated the occurrence of pneumonia and improved growth rates, while also modulating the prevalence of bacteria and protozoa in preweaning Gyr × Holstein calves.

Effects of supplementing a direct-fed microbial containing Enterococcus faecium 669 on performance, health, and metabolic responses of preweaning Holstein dairy calves

This study aimed to evaluate the effects of Enterococcus faecium 669 supplementation on performance, health, parasitological, microbiological, and hematological responses of preweaning dairy calves. Forty-two newborn Holstein female calves (initial body weight [BW] 44 ± 4.5 kg) were used in the present study. At birth, calves were ranked by initial BW and assigned to 1 of 2 treatment groups: (1) whole milk (CON; n = 21) and (2) whole milk with the addition of direct-fed microbial Ent. faecium 669 (DFM; n = 21). During the entire experimental period (63 d), DFM was daily-fed at a rate of 2.5 × 109 cfu/head. All calves were offered a mixture of a starter feed and wheat straw for ad libitum consumption. Supplement intake was evaluated daily, whereas calves were weighed on a weekly basis from d 0 to weaning (d 63). Diarrhea was assessed once a day, and fecal and blood samples were collected for microbiological, parasitological, and hematological responses. All data were analyzed with SAS using calf as the experimental unit. A treatment × week interaction was observed for BW, as DFM-supplemented calves were heavier than CON cohorts on d 56 (+ 4.7 kg) and at weaning on d 63 (+ 4.8 kg). A similar interaction was observed for average daily gain (ADG) and dry matter intake (DMI), with greater ADG for DFM-supplemented calves from d 35 to 42, greater ADG and DMI from d 49 to 56, and greater DMI from d 56 to weaning. Moreover, diarrhea occurrence tended to be lower, whereas rectal temperature was 0.2°C lower for DFM-supplemented calves. Treatment × day interactions were observed for the occurrence and counts of Eimeria spp., as DFM-supplemented calves tended to have a reduced number of positive observations on d 42 of the study versus CON, and a significant reduction in positive animals from d 21 to 42 was observed in the DFM group but not in CON calves. For Cryptosporidium spp., no treatment effects were observed on overall occurrence (%), but DFM-supplemented calves had a greater count of oocyst per gram versus CON. No treatment × day interaction or main treatment effects were observed for any of the blood variables analyzed herein, exception being monocytes concentration. In summary, preweaning Ent. faecium 669 supplementation improved performance, diarrhea occurrence, and reduced the number of calves positively-detected for Eimeria spp.

Effect of synbiotics on growth performance, gut health, and immunity status in pre-ruminant buffalo calves

Synbiotics are employed as feed additives in animal production as an alternate to antibiotics for sustaining the gut microbiota and providing protection against infections. Dairy calves require a healthy diet and management to ensure a better future for the herd of dairy animals. Therefore, the present study was carried out to investigate the effect of synbiotics formulation on growth performance, nutrient digestibility, fecal bacterial count, metabolites, immunoglobulins, blood parameters, antioxidant enzymes and immune response of pre-ruminant Murrah buffalo calves. Twenty-four apparently healthy calves (5 days old) were allotted into four groups of six calves each. Group I (control) calves were fed a basal diet of milk, calf starter and berseem with no supplements. Group II (SYN1) calves were fed with 3 g fructooligosaccharide (FOS) + Lactobacillus plantarum CRD-7 (150 ml). Group III (SYN2) calves were fed with 6 g FOS + L. plantarum CRD-7 (100 ml), whereas calves in group IV (SYN3) received 9 g FOS + L. plantarum CRD-7 (50 ml). The results showed that SYN2 had the highest (P < 0.05) crude protein digestibility and average daily gain compared to the control. Fecal counts of Lactobacilli and Bifidobacterium were also increased (P < 0.05) in supplemented groups as compared to control. Fecal ammonia, diarrhea incidence and fecal scores were reduced in treated groups while lactate, volatile fatty acids and antioxidant enzymes were improved compared to the control. Synbiotic supplementation also improved both cell-mediated and humoral immune responses in buffalo calves. These findings indicated that synbiotics formulation of 6 g FOS + L. plantarum CRD-7 in dairy calves improved digestibility, antioxidant enzymes, and immune status, as well as modulated the fecal microbiota and decreased diarrhea incidence. Therefore, synbiotics formulation can be recommended for commercial use in order to achieve sustainable animal production.

Insights into the Prognostic Role of Serum Interleukin-6 and Hematobiochemical Alterations in Cattle during Recent Outbreaks of Lumpy Skin Disease in Lodhran District, Pakistan

Lumpy skin disease (LSD) is a highly infectious disease of cattle caused by a virus of the Poxviridae family, genus Capripoxvirus. The present study was designed to determine the prognostic ability of serum IL-6 in LSD using a binary logistic regression model at baseline sampling. A 17-day cohort study was conducted on a recent outbreak of LSD among cattle in the Lodhran District of Punjab, Pakistan. Infected cattle were divided into two categories based on their clinical status on day 17 as recovered (n = 33) or unrecovered (n = 17). Nodular lesions and scab specimens (n = 50) were used for the isolation of the lumpy skin disease virus and were confirmed by PCR. In recovered animals, hematological results showed marked leukocytosis, eosinophilia, lymphocytosis, neutrophilia, and monocytopenia. However, marked erythrocytosis, leukopenia, and thrombocytopenia were observed in the unrecovered animals at the final sampling point of the study. Serum levels of total protein, albumin, and glucose were significantly higher in the recovered animals. Meanwhile, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, creatinine phosphokinase, total bilirubin, and direct bilirubin were found considerably higher in the unrecovered group. Receiver-operating characteristic curve analysis for serum IL-6 at baseline predicts the extended clinical conditions at the cut-off value of 85.16 pg/mL (55% specificity, 94% sensitivity, area under the curve 0.8039, respectively). In conclusion, the disease-induced hematological and biochemical alterations were significantly ameliorated in the recovered animals. In addition, the study revealed that serum IL-6 can be used as a valid marker for predicting the clinical worsening of LSD in cattle.

Combined effect of probiotics and specific immunoglobulin Y directed against Escherichia coli on growth performance, diarrhea incidence, and immune system in calves

Enterotoxigenic Escherichia coli (ETEC) K99 is one of the major pathogens associated with calf diarrhea. The induction of passive immunity in animals by immunoglobulin Y and using probiotics are inexpensive alternatives to antibiotics for the prevention and treatment of a number of bacterial infections, including diarrhea. Hence, the aim of this research was to evaluate the impact of dietary probiotics and ETEC K99-specific egg yolk antibody supplements, alone and in combination with each other, on health and growth parameters, diarrhea incidence and immune stimulation in newborn Holstein calves. One hundred and twenty neonatal calves were allocated randomly into 4 dietary groups (n = 30 per group) received colostrum/milk without any additives (control group), or supplemented with egg yolk powder contained E. coli K99-specific antibody (Ab group; 1 g/day), a commercial probiotic, Hypro-calves (Pro group; 3 g/day), and their combination (Ab+Pro group), from day (d) 1 to d28 of age. Analyses of the growth parameters, feed efficiency, fecal score, and microbiota and immune function were carried out on d0, 14, 21, and 28 of the experiment. Calves in Ab or Ab+Pro group had higher (P < 0.05) average daily gain compared to control and Pro groups during 0-14d. Feed efficiency of calves in Ab and Ab+Pro groups was significantly higher than that in control group during the period of 0-14d; however, no significant differences were observed in 0-28d period. Diarrhea prevalence and fecal score in Ab+Pro group were lower than control group (P < 0.05). Calves in Ab+Pro group had the lowest number of fecal E. coli in comparison to other groups on d28 (P < 0.05). Feeding Ab+Pro supplement increased (P < 0.05) concentrations of blood IgA and serum CD4 compared to the control group. Likewise, calves in Pro group had higher CD4 levels as compared to the control calves (P < 0.05). Serum concentration of interferon-gamma in control group was lower than other groups (P < 0.05). Overall, these data suggest that feeding a combination of probiotic and specific antibody against ETEC to neonate Holstein calves enhances feed efficiency, boosts immunity, and reduces diarrhea prevalence.

Systematic review of an intervention: the use of probiotics to improve health and productivity of calves

The aims of this study were to undertake a systematic review and meta-analysis of the types of probiotic formulations that are commercially available and to critically appraise the available evidence for the effectiveness of probiotics in improving the health and productivity of calves. Relevant papers were identified to answer the question: 'In calves aged between birth to one year, is the use of probiotics associated with changes in haematological or biochemical parameters, faecal bacteria counts, average daily live weight gain, dry matter intake, or feed conversion ratio?' The search of the literature yielded 67 studies that fit the primary screening criteria. Included studies were assessed for bias and confounding using a predefined risk assessment tool adapted from the Cochrane Collaboration's tool for assessing risk of bias in randomised trials and GRADE guidelines. Meta-analysis was performed using Review Manager and R. Random sequence generation was low in more than 59 % of studies. Risk of allocation concealment and performance bias were largely unclear in over 68 % of studies. Calves fed probiotics had increased average daily live weight gains (ADG) from birth to weaning (mean difference [MD] = 83.14 g/d 95 % CI = 58.36-107.91, P < 0.001) compared with calves on a control diet. Calf age reduced the level of heterogeneity of the effect of probiotics on ADG for calves between one to three weeks of age (τ² = 73.15; I² = 4%; P = 0.40) but not for calves older than three weeks of age (τ² = 2892.91; I² = 73 %; P < 0.001). Feed conversion ratio (FCR) was lower for calves on probiotics (MD = -0.13 kg of dry matter intake (DMI) to kg of live weight (LW) gain, 95 % CI = -0.17 to -0.09, P < 0.001), and the heterogeneity of effect was large in younger aged calves (τ² = 0.05; I² = 78 %; P = 0.03). The risk of bias regarding the methodology in the included studies was high. The quality of evidence for each outcome was categorised as moderate. There is sufficient data to support the effectiveness of probiotic use in some applications such as for the improvement of performance and productivity parameters of calves. However, the evidence is weak for other potential probiotic uses in calves such as improved health and reduced risk of disease. Therefore, the existing data are inconclusive and do not support the use of probiotics as an alternative to antimicrobials to improve calf health and productivity.

Supplementing neonatal Jersey calves with a blend of probiotic bacteria improves the pathophysiological response to an oral Salmonella enterica serotype Typhimurium challenge

The objectives of the current study were to determine the effects of supplementing a blend of probiotic bacteria (Provida Calf, MB Nutritional Sciences, Lubbock, TX) on the pathophysiological response to an oral Salmonella enterica serotype Typhimurium challenge in neonatal Jersey calves. Twenty-four Jersey bull calves within 24 h of birth were acquired from a local calf ranch, blocked by total serum protein and initial body weight, and randomly assigned to 1 of 3 treatments (n = 8). Calves were assigned to either (1) Control (CON); base milk replacer, (2) Control + Salmonella Typhimurium (CON+ST); base milk replacer and challenged with Salmonella Typhimurium on d 7; or (3) Provida Calf probiotics + Salmonella Typhimurium (PRO+ST); same milk replacer supplemented with a proprietary blend of Lactobacillus casei and Enterococcus faecium strains and challenged with Salmonella Typhimurium on d 7. The PRO+ST calves were supplemented for the first 3 d with 2 × 10¹⁰ cfu/d and then with 2 × 10⁹ cfu/d for the remainder of the study. The CON+ST and PRO+ST calves were each challenged with approximately 5 × 10⁶ cfu of Salmonella Typhimurium (ATCC# 14028), which was a mild challenge that did not cause scours in the calves. Peripheral blood samples were collected on d 0, 7, 10, 14, and 21 and analyzed for hematology; serum was collected and analyzed for haptoglobin, glucose, and urea N. Rectal temperatures were collected daily from d 6 to 21, when all calves were killed, so that persistent colonization of Salmonella Typhimurium and histomorphology of both the duodenum and ileum could be determined. Serum haptoglobin and urea N concentrations were increased among CON+ST on d 10. In contrast, the peak rectal temperature on d 10 in PRO+ST calves was 40.4°C, which was greater than that for CON and CON-ST (38.9°C and 39.7°C, respectively). The neutrophil percentage in peripheral circulation in PRO+ST calves was 55.4%, which was greater than that for CON and CON+ST (34.8 and 41.8%, respectively). Seven of the 8 PRO+ST calves had elevated neutrophil percentages on d 10 compared with d 7, whereas 4 of the 8 CON+ST calves had reduced neutrophil percentages on d 10 compared with d 7. Villus height-to-crypt depth ratios in the duodenum were greater among CON and PRO+ST calves, being 1.38, 0.84, and 1.43 for CON, CON+ST, and PRO+ST, respectively. In the ileum, the PRO+ST calves had greater villus height-to-crypt depth ratios than both the CON and CON+ST calves (1.64, 1.53, and 2.43 for CON, CON+ST, and PRO+ST, respectively). These data indicate that supplementing neonatal calves with the blend of probiotic bacteria used in the current study can influence the pathophysiological response to a mild enteric Salmonella Typhimurium challenge.

Immunobiotics for the Bovine Host: Their Interaction with Intestinal Epithelial Cells and Their Effect on Antiviral Immunity

The scientific community has reported several cases of microbes that exhibit elevated rates of antibiotic resistance in different regions of the planet. Due to this emergence of antimicrobial resistant microorganisms, the use of antibiotics as promoters of livestock animals' growth is being banned in most countries around the world. One of the challenges of agricultural immunology therefore is to find alternatives by modulating the immune system of animals in drug-independent safe food production systems. In this regard, in an effort to supplant antibiotics from bovine feeds, several alternatives were proposed including the use of immunomodulatory probiotics (immunobiotics). The purpose of this review is to provide an update of the status of the modulation of intestinal antiviral innate immunity of the bovine host by immunobiotics, and the beneficial impact of immunobiotics on viral infections, focused on intestinal epithelial cells (IECs). The results of our group, which demonstrate the capacity of immunobiotic strains to beneficially modulate Toll-like receptor 3-triggered immune responses in bovine IECs and improve the resistance to viral infections, are highlighted. This review provides comprehensive information on the innate immune response of bovine IECs against virus, which can be further investigated for the development of strategies aimed to improve defenses in the bovine host.

Serum interleukin-6 as a prognostic marker in neonatal calf diarrhea

Neonatal calf diarrhea is still one of the most important diseases in calf rearing, and severe diarrhea has a marked effect on animal welfare. Furthermore, significant economic losses can result from this disease due to high mortality rates, high medical costs, and low weight gain. To avoid a fatal outcome of the disease, it is crucial that vulnerable calves are identified as early as possible. Interleukin-6 is described as an early and reliable prognostic marker in several diseases. In this study, 20 scouring calves were tested by ELISA for their IL-6 serum concentrations. Samples were collected twice, at the beginning of diarrhea and 7 to 10 d later. Regarding the clinical outcome after 7 to 10 d, calves were classified as recovered or nonrecovered. A receiver operating characteristic analysis was conducted to determine the prognostic value of IL-6 for the progress of clinical symptoms. At the beginning of diarrhea, the IL-6 concentration was significantly higher in nonrecovering calves compared with those that recover 7 to 10 d after the onset of diarrhea. Interleukin-6 proved to be a useful additional parameter in the clinical examination. High initial IL-6 values can support the decision for closer monitoring and an adapted therapeutic strategy for the respective calves. This may help to prevent unnecessary animal suffering and reduce economic losses.

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.