Influence of early use of antimicrobial on the health and performance of Holstein calves in the first month of life

High frequency of multidrug-resistant Escherichia coli from cattle in the Cerrado and Pantanal biomes of Brazil

The indiscriminate use of antimicrobials has led to the emergence of resistant bacteria, especially pathogenic strains of Escherichia coli, which are associated with diseases in animals and humans. The aim of the present study was to characterize E. coli isolates in calves with regards to the presence of virulence genes and investigate the resistance of the isolates to different antimicrobials. Between 2021 and 2023, 456 fecal samples were collected from calves in the Pantanal and Cerrado biomes of the state of Mato Grosso do Sul, Brazil. All samples were subjected to microbiological analysis and disc diffusion antibiogram testing. The polymerase chain reaction method was used to detect virulence genes. Bacterial growth was found in 451 of the 456 samples and biochemically identified as Escherichia coli. All 451 isolates (100 %) exhibited some phenotypic resistance to antimicrobials and 67.62 % exhibited multidrug resistance. The frequency of multidrug-resistant isolates in the Cerrado biome was significantly higher than that in the Pantanal biome (p = 0.0001). In the Cerrado, the most common pathotype was Shiga toxin-producing Escherichia coli (STEC) (28 %), followed by toxigenic Escherichia coli (ETEC) (11 %), enterohemorrhagic Escherichia coli (EHEC) (8 %) and enteropathogenic Escherichia coli (EPEC) (2 %). In most cases, the concomitant occurrence of pathotypes was more common, the most frequent of which were ETEC + STEC (33 %), ETEC + EHEC (15 %) and ETEC + EPEC (3 %). The STEC pathotype (30 %) was also found more frequently in the Pantanal, followed by EHEC (12 %), ETEC (9 %) and EPEC (6 %). The STEC pathotype had a significantly higher frequency of multidrug resistance (p = 0.0486) compared to the other pathotypes identified. The frequency of resistance was lower in strains from the Pantanal biome compared to those from the Cerrado biome. Although some factors are discussed in this paper, it is necessary to clarify the reasons for this difference and the possible impacts of these findings on both animal and human health in the region.

A scoping review of neonatal calf diarrhea case definitions

Various case descriptions and scoring systems have been used to define neonatal calf diarrhea (NCD) and diverse diarrhea-related outcomes are reported, which limits direct comparison between studies. Therefore, the objective of this scoping review was to characterize the case definitions used for NCD and describe diarrhea-related outcomes to inform future efforts towards standardization. A literature search identified articles using 3 databases (Medline, CAB Direct, Agricola), along with Google and Google Scholar. This returned 16,854 unique articles, which were then screened for eligibility by two independent reviewers, resulting in 555 being selected for data extraction. Among articles, the study populations included mostly dairy-breed calves (88%; n = 486) while the remainder evaluated beef, crossbred, or dual purpose beef/dairy calves (10%; n = 53), or did not report breed (3%; n = 16). Studies used between 1 and 8 metrics to define NCD, with 933 unique metrics extracted in total. The most common metric was fecal consistency alone (30%; n = 281), or with at least 1 other metric (26%; n = 241). To define diarrhea, fecal consistency was either described qualitatively (e.g., "profuse liquid feces"), or semi-quantitatively, for example using a scoring system that frequently included 4 levels (n = 208). Some NCD case definitions included fecal color, volume, or odor (10%; n = 98), physical exam parameters (8%; n = 79), the duration of abnormal feces (7%; n = 67), the presence of abnormal contents (e.g., blood, 7%; n = 61), farm treatment records (6%; n = 54), fecal dry matter (1%; n = 12), or another metric (4%; n = 41). One or more references were cited for the NCD case definition by 49% of studies (n = 273/555), with the most common references being Larson et al. (1977) (n = 85), and McGuirk (2008) (n = 59). In the 555 included articles, 979 unique diarrhea-related outcomes were found, most commonly a binary categorization of calves having or not having diarrhea (49%; n = 483). Other articles reported statistical outcomes calculated from fecal scores (16%; n = 159), multiple diarrhea severities (10%; n = 95), or the age calves first developed NCD (8%; n = 76). This review characterized substantial heterogeneity among NCD case definitions and diarrhea-related outcomes, which limits interpretation and comparison of studies. Future work is required to develop and validate reporting standards for NCD to optimize knowledge synthesis and support rigorous and ethical calf health research.

Effect of prophylactic use of tulathromycin on gut bacterial populations, inflammatory profile and diarrhea in newborn Holstein calves

This objective of this study was to evaluate the use of tulathromycin on the timing of appearance and number of four indicator organisms representing the gastrointestinal microbial community, the incidence of diarrhea and a measure of the systemic inflammatory profile in Holstein heifers. Twenty-six Holstein heifer calves were distributed between receiving (ATB+) or not receiving (ATB-) tulathromycin at a dose of 2.5 mg/kg by 12 h of age. Samples from the calves were collected at six times during the neonatal period. Stool samples were used to determine the dry matter content and quantitative analysis of specific indicator bacterial populations. Samples of whole blood and serum were collected to determine the total number of neutrophils, the number of CD62L+ neutrophils, quantity of haptoglobin, and to allow for ex vivo measurement of reactive oxygen species. A higher frequency of diarrhea was detected in the ATB+ calves (84.6%) than ATB- (53.8%) on days 13-15 (P = 0.084). ATB- calves had a greater number of Bifidobacterium in stool on day 3-5 (P = 0.002), and on days 7-9 (P = 0.018). The ATB+ calves tended to have a higher number of Escherichia coli in stool on days 20-23 and days 27-30 (P = 0.052 and P = 0.072). Both the total number of neutrophils (P = 0.013) and the capacity for ROS production was higher in ATB- (P = 0.038) than ATB+ calves at all points tested. ATB+ calves had higher levels of haptoglobin (P = 0.032) on days 13-15. Administration of tulathromycin appeared to negatively impact the establishment of a normal microbiome and to modulate the development of innate immune function.

Zootechnical and health performance of Holstein x Gir crossbred calves

Crossbreeding is used to increase production and disease resistance in adult animals, and there is no research to assess the performance of animals in the early stages. The aim of this study was to evaluate the zootechnical and health performance of Holstein x Gir calves (½ HG: ½ Dutch ½ Gir and ¾ HG: ¾ Dutch ¼ Gir), from birth to 80 days of age, and compare metabolic parameters between groups. In this sense, calves were monitored for zootechnical parameters; epidemiological indexes such as morbidity, mortality, recurrence of diarrhea, pneumonia, and other diseases; as well as serum concentrations of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transferase, total proteins, cholesterol, triglycerides, albumin, urea, and paraoxonase1 (PON1). ¾ HG calves showed higher morbidity for diarrhea and remained with diarrhea for longer compared to ½ HG calves, and this was reflected in the average daily weight gain until the 42nd day, with ½ HG calves performing better. There were no differences regarding passive immune transfer between groups, as well as no differences in morbidity and mortality from pneumonia. Regarding biochemical analyses, a difference was found only in the concentrations of PON1, which were higher in ¾ HG calves. The findings show that blood degree influences the occurrence and duration of diarrhea, negatively impacting the zootechnical performance of the animals. Crossbreeding bulls with zebu cattle can be an alternative to increase calf resistance and reduce diarrhea, thus lowering economic losses and improving animal performance.