Niel A Karrow

University of Guelph | UOGuelph · Department of Animal Biosciences

Toll-like receptor 4 (TLR4) encodes an innate immune cell pattern-recognition receptor implicated in the recognition of Mycobacterium avium subsp. paratuberculosis (MAP), the causative agent of Johne's disease in ruminants. Polymorphisms in TLR4 have been associated with susceptibility to MAP infection. In this study, a previously developed TLR4 kn...

Dairy cattle face a variety of stressful events on a daily basis. More specifically, climate change has resulted in more frequent heat stress events that increase the incidence of chronic bacterial infections by inducing conditions like leaky gut syndrome, whereby the integrity of the intestinal epithelium is compromised allowing for luminal bacter...

Animals respond to stress by activating a wide array of physiological and behavioral responses that are collectively referred to as the stress response. MicroRNAs (miRNAs) are small, noncoding RNAs that play key roles in the regulation of homeostasis. There are many reports demonstrating examples of stress-induced miRNA expression profiles. The aim...

Gastrointestinal nematode (GIN) infections are considered the most important disease of grazing sheep and due to increasing anthelmintic resistance, chemical control alone is inadequate. Resistance to Gastrointestinal nematode infection is a heritable trait, and through natural selection many sheep breeds have higher resistance. Studying the transc...

Frequently reported occurrences of deoxynivalenol (DON), beauvericin (BEA), and, to a lesser extent, ochratoxin A (OTA) and citrinin (CIT) in ruminant feed or feedstuff could represent a significant concern regarding feed safety, animal health, and productivity. Inclusion of yeast cell wall-based mycotoxin adsorbents in animal feeds has been a comm...

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are commonly detected as natural contaminants in agricultural commodities worldwide. Mycotoxin exposure can lead to mycotoxicosis in both animals and humans when found in animal feeds and food products, and at lower concentrations can affect animal performance by disrupti...

High incidence of traditional and emerging Fusarium mycotoxins in cereal grains and silages can be a potential threat to feed safety and ruminants. Inadequate biodegradation of Fusarium mycotoxins by rumen microflora following ingestion of mycotoxin-contaminated feeds can lead to their circulatory transport to target tissues such as mammary gland....

In the original publication [...]

Knowledge that certain nutraceuticals can modulate the immune system is not new. These naturally occurring compounds are known as immunoceuticals, which is a novel term that refers to products and systems that naturally improve an individual’s immuno-competence. Examples of immunoceuticals include vitamin D3, mushroom glycans, flavonols, quercetin,...

N-acetylcysteine (NAC), an acetylated derivative of the amino acid L-cysteine has been widely used as a mucolytic agent and antidote for acetaminophen overdose since the 1960s and the 1980s respectively. NAC possesses antioxidant, cytoprotective, anti-inflammatory, antimicrobial and mucolytic properties, making it a promising therapeutic agent for...

Despite the increasing interest and use of NAC over the decades, there remains much debate surrounding NAC’s mechanisms of action. It was widely believed that NAC exerts its antioxidant and cytoprotective properties through its ability to act as a scavenger of reactive oxygen species, a precursor for glutathione biosynthesis, and a disulfide reduct...

Parasitism by gastrointestinal nematodes (GINs) is a major source of morbidity and mortality for sheep flocks grazed on pasture. Since there is evidence for genetic resistance to GINs in some sheep breeds, genetic selection for immunologic resistance to GIN is a possible management strategy. This study sought to identify differences at the transcri...

Frequent detection of mycotoxins ochratoxin A (OTA) and citrinin (CIT) in ruminant feed and feedstuff can be a potential threat to feed safety, animal performance and health. Ineffective biodegradation of these mycotoxins by rumen microflora following ingestion of contaminated feeds can lead to their circulatory transport to tissues such as mammary...

The cow’s milk production characteristics are a significant economic indicator in the livestock industry. Serum cytokines such as interleukin-17 (IL-17) may be potential indicators for bovine mastitis concerning the milk somatic cell count (SCC) and somatic cell score (SCS). The current study aims to find previously undiscovered single nucleotide p...

Three hundred twenty newly weaned pigs (21 days of age; 6.7±0.3 kg BW) were used to determine the effects of supplementing low-complexity (LC) deoxynivalenol- (DON) contaminated nursery diets with a feed additive or fish oil on growth performance and immune response to an Escherichia coli lipopolysaccharide (LPS) challenge. Pens were randomly assig...

This research paper aimed to explore the characteristics of Holstein cattle's milk fat percentage lactation curve and its influencing factors. The Wood model was used for fitting the lactation curve of 398,449 DHI test-day milk fat percentage records of Holstein cows from 2018 to 2020 in 12 dairy farms in Jiangsu province, and the influencing facto...

Dairy cattle routinely face a variety of stressors. For example, climate change has resulted in more frequent heat stress events that increase the incidence of bacterial infections by inducing conditions like leaky gut syndrome, whereby the integrity of the intestinal epithelium is compromised allowing for luminal bacteria and their membrane compon...

In this study, circular RNAs (circRNAs) from Holstein cow mammary tissues was identified and compared between early lactation and non-lactation. After analysis, 10,684 circRNAs were iden-tified, ranging from 48 to 99,406 bp, and the average size was 882 bp. The circRNAs were mainly distributed on chromosomes 1 to 11, and 89.89% of the circRNAs belo...

Heat stress during late gestation could affect subsequent lactation performance, resulting in damage to the immune function, health, and growth performance of calves. This study aimed to compare the effects of 33 days of summer stress (Summer group, 70.15 < THI < 74.28) with 33 days of winter during late gestation (Winter group, 57.55 < THI < 67.25...

Background The current study was conducted to investigate the individual and combined occurrence of aflatoxin B 1 (AFB 1 ), deoxynivalenol (DON) and zearalenone (ZEN) in feeds from various Provinces of China during 2018 to 2020. A total of 3,507 feed samples, including 2,090 feed ingredients and 1,417 complete feed samples, were collected from diff...

Vaccines have been developed at “warp speed” to combat the COVID-19 pandemic caused by the SARS-CoV-2 coronavirus. Although they are considered the best approach for preventing mortality, when assessing the safety of these vaccines, pregnant women have not been included in clinical trials. Thus, vaccine safety for this demographic, as well as for t...

Pathogens induce neuroendocrine-immune interactions in their hosts, which are a basis to overcome the microbial stressor. These interactions result in individual variation of the hypothalamic-pituitary-adrenal (HPA) axis response and could contribute to variable stress resiliency. In present study, a comprehensive set of circulatory markers was ass...

Gastrointestinal nematode infection is one of the major production problems for sheep producers worldwide due its high incidence, morbidity, and mortality in affected flocks. The study of long non-coding RNA (lncRNA) in liver tissue of high (HIR) and low immune responder (LIR) sheep to GINs using RNA-Sequencing technology may provide a better under...

One hundred eighty newly weaned pigs (21 days of age; 6.9±0.2 kg BW) were used to determine the effects of deoxynivalenol- (DON) contaminated corn and an immune-modulating feed additive on growth performance and immune response of nursery pigs fed corn- and soybean meal-based diets. Pens were randomly assigned to 1 of 5 diets: a high-complexity (HC...

Johne’s disease (JD), also known as paratuberculosis, is a severe production-limiting disease with significant economic and welfare implications for the global cattle industry. Caused by infection with Mycobacterium avium subspecies paratuberculosis (MAP), JD manifests as chronic enteritis in infected cattle. In addition to the economic losses and...

The membranes of Gram-negative bacteria (GNB) such as Escherichia coli contain a molecule called lipopolysaccharide (LPS). LPS contains a lipid A tail that is recognized by lipopolysaccharide binding protein (LBP) following host infection. Given the rise of antibiotic resistance (ABR), risks to human health, and the negative effects that GNB infect...

Individual variation of the hypothalamic-pituitary-adrenal (HPA) axis response to stress could contribute to variable stress resiliency of livestock. During stress events, the innate immune system can also become activated and work in concert with the neuroendocrine system to restore homeostasis, while minimizing tissue damage. The purpose of this...

Toll-like receptor 4 (TLR4) is a pattern-recognition receptor involved in the recognition of microbial pathogens and host alarmins. Ligation to TLR4 initiates a signaling cascade that leads to inflammation. Polymorphisms in bovine TLR4 have been associated with Mycobacterium avium ssp. paratuberculosis (MAP) susceptibility and resistance, the cause...

The objective of this study was to explore the mechanism of Hedyotis diffusa (HD) in mediating the detoxification of aflatoxin B1 (AFB1)-induced hepatic injury in chicks. A total of 144 one-day-old male broilers (Cobb 500) were randomly assigned to four treatment groups (n = 6 cages/diet, 6 chicks/cage). After three days of acclimation, the broiler...

One hundred and forty-four newly weaned pigs (6.74 ± 0.23 kg initial BW; 21 days of age) were used to determine the effect of partially replacing animal protein sources with black solider fly larvae meal (BSFLM) in nursery diets on growth performance, gut morphology, and immune response. After weaning, pigs were placed in 24 pens (6 pigs per pen) a...

The objective of this study was to evaluate the efficacy of mycotoxin binders in reducing the adverse effects of co-occurring dietary aflatoxin B1 (AFB1), deoxynivalenol (DON) and ochratoxin A (OTA) on laying hens. Three hundred and sixty 26-week-old Roman laying hens were randomly allocated into four experimental groups with 10 replicates of nine...

Cell envelope proteins from Mycobacterium avium subspecies paratuberculosis (MAP) that are antigenically distinct from closely related mycobacterial species are potentially useful for Johne's Disease (JD) diagnosis. We evaluated the potential of ELISAs, based on six antigenically distinct recombinant MAP cell envelope proteins (SdhA, FadE25_2, FadE...

Improving the quality of milk is a challenge for zootechnicians and dairy farms across the globe. Long-chain acyl-CoA synthetase 1 (ACSL1) is a significant member of the long-chain acyl-CoA synthetase gene family. It is widely found in various organisms and influences the lactation performance of cows, including fat percentage, milk protein percent...

Infection with gastrointestinal nematode parasites (GINs) is an important cause of productivity loss on sheep farms in Ontario and worldwide. However, efforts to quantify the effect of GIN infection on growth have demonstrated mixed results. Furthermore, there has been limited investigation of their effect on reproductive performance. This study ev...

Background The interleukin-10 receptor alpha ( IL10RA) gene codes for the alpha chain of the IL-10 receptor which binds the cytokine IL-10. IL-10 is an anti-inflammatory cytokine with immunoregulatory function during the pathogenesis of many inflammatory disorders in livestock, including Johne’s disease (JD). JD is a chronic enteritis in cattle cau...

To meet the growing consumer demand for chicken meat, the poultry industry has selected broiler chickens for increasing efficiency and breast yield. While this high productivity means affordable and consistent product, it has come at a cost to broiler welfare. There has been increasing advocacy and consumer pressure on primary breeders, producers,...

The objective of this study was to use isobaric tags for relative and absolute quantitation (iTRAQ) proteomic technology to systematically analyze the hepatotoxic mechanism of aflatoxin B1 (AFB1) and its prevention by Se in broilers. Four groups of day-old broilers were allocated into a 2×2 factorial design trial that fed a Se-deficient based diet...

Bovine milk contains bioactive components that are nutritionally and immunologically important to calves and humans. Dairy cows classified as high (H) immune responders using the patented high immune response technology have higher concentrations of immunoglobulin and specific antibodies in sera and milk compared with average (A) and low (L) respon...

The objective of the current study was to evaluate the immunotoxic effects of deoxynivalenol (DON) in weaning piglets, and potential efficacy of a novel modified hydrated sodium calcium aluminosilicate (HSCAS) binder to detoxify DON toxicity. Four groups of 21-day-old male piglets (n = 7/group) were fed a control diet or diet adding 1.0 or 3.0 mg D...

1. The impact of feeding sources of n-3 fatty acids (FA) to ISA Brown and Shaver white breeders and their offspring on antibody titres and plasma FA profile was examined. 2. Breeders were fed either a control diet (CON); CON + 1% microalgae (DMA: Aurantiochytrium limacinum) as a source of docosahexaenoic acid; or CON + 2.6% of a co-extruded mixture...

Host–pathogen interactions are complex and influenced by host genetic and epigenetic modifications. Recently, the significance of microRNAs (miRNAs) in pathogenic infection and the regulation of immune response has been highlighted. However, information on miRNAs’ role in the course of inflammation is still very limited in small ruminants. The pres...

Staphylococcus aureus intramammary infection is one of the most common causes of chronic mastitis in dairy cows, whose development may be associated with epigenetic changes in the expression of important host defense genes. This study aimed to construct a genome-wide DNA methylation profile of the mammary gland of Chinese Holstein cows (n = 3) foll...

To meet the growing consumer demand for chicken meat, the poultry industry has selected broiler chickens for increasing efficiency and breast yield. While this high productivity means affordable and consistent product, it has come at a cost to broiler welfare. There has been increasing advocacy and consumer pressure on primary breeders, producers,...

Stressors experienced by layer breeders during egg production can lead to changes in the egg hormone content, potentially impacting their offspring, the commercial layers. Genetic differences might also affect the offspring's susceptibility to maternal experiences. In this study, we tested if maternal stress affects measures of stress and fear in f...

Leveraging mucosal immunity is a promising method for controlling gastrointestinal nematode (GIN) parasitism in sheep. Salivary antibody to carbohydrate larval antigen (sCarLA), a heritable measure of immunity to third-stage GIN larvae (L3), has been successfully applied to genetic improvement programs in New Zealand. However, sCarLA levels wane in...

Osteoarthritis (OA) is a chronic joint disease afflicting a substantial portion of the world’s population with no currently available cure. Mesenchymal stem cell (MSC)-based therapies have been observed to have a mild beneficial effect in OA but the mechanism behind their action remains unclear. This study aimed to identify the lymphocytic response...

Disbudding is a common procedure practiced in the dairy industry and is known to cause pain when performed without pain control. Dairy producers who disbud calves with caustic paste are less likely to provide pain control than those using cautery. Little research has been conducted on pain control for caustic paste disbudding and no studies have sp...

Background: Johne’s disease (JD) is a chronic intestinal inflammatory disease caused by Mycobacterium avium subsp. paratuberculosis (MAP) infection in ruminants. Since there are currently no effective vaccine or treatment options available to control JD, genetic selection may be an alternative strategy to enhance JD resistance. Numerous Single Nucl...

As the temperature-humidity index (THI) increases, animals are less able to regulate body temperature leading to decreases in production and immune function. The High Immune Response (HIR™) technology classifies animals based on estimated breeding values (EBVs) of their IR capacity as high (H), average (A), or low (L). H-responders with their uniqu...

This study investigated the single nucleotide polymorphisms (SNPs) of Fatty acid desaturase 2 (FADS2) gene and further explored their genetic effects on conventionally collected milk production traits in Chinese Holstein cows using 18,264 test-day records of 841 cows. One missense mutation c. 908 C > T (SNP site in the complementary DNA sequence),...

Breeding stress-resilient livestock is a potential strategy to help mitigate the negative effect of environmental and pathogenic stressors. The hypothalamic-pituitary-adrenal axis and immune system are activated during stress events and release mediators into the circulation that help restore physiological homeostasis. The purpose of this study was...

Mixed gastrointestinal nematode (GIN) infections are a common and significant cause of financial loss for small ruminant producers. Morphologic examination of third-stage larvae (L3) can be used to identify species composition in feces but has limitations due to the requirement for specialized expertise and the extensive time (8–15 d depending on m...

Maternal stress can affect the offspring of birds, possibly due to hormone deposition in the egg. Additionally, phenotypic diversity resulting from domestication and selection for productivity has created a variety of poultry lines that may cope with stress differently. In this study, we investigated the effects of maternal stress on the behavior o...

Stressors experienced by layer breeders during egg production can lead to changes in the egg hormone content, potentially impacting their offspring, the commercial layers. Genetic differences might also affect the offspring's susceptibility to maternal experiences. In this study, we tested if maternal stress affects measures of stress and fear in f...

The present work aimed at assessing passive, innate, and acquired immunity in piglets from sows supplemented with either organic or inorganic selenium (Se). A total of 12 multiparous pregnant sows were randomly allocated to three groups: selenium-deficient, corn and soy–based diet base diet (BD), 0.3 mg Se/kg as hydroxy-selenomethionine (OH-SeMet),...

Early-life exposure to stressors can shape the phenotype of the offspring resulting in changes that may affect their prehatch and posthatch development. This can be modeled indirectly through maternal exposure to stressors (natural model) or by offspring exposure to stress hormones (pharmacological model). In this study, both models were used to in...

Offspring adrenal function may be negatively affected in utero by maternal stressors such as microbial infection. Maternal supplementation with immunomodulatory compounds such as omega-3 polyunsaturated fatty acids (n-3 PUFA) may help minimize the adverse effects of maternal stress on fetal hypothalamic-pituitary-adrenal development and may improve...

Mycotoxins are toxic secondary fungal metabolites that commonly contaminate crops and food by-products and thus, animal feed. Ingestion of mycotoxins can lead to mycotoxicosis in both animals and humans, and at subclinical concentrations may affect animal production and adulterate feed and animal by-products. Mycotoxicity mechanisms of action (MOA)...