Niel A Karrow

• Ph.D.
• Professor (Full) at University of Guelph

Nuclear receptor coactivator 6 is a gene that produces a protein that regulates transcriptional activity. It is also involved in many processes like cell survival, metabolism, homeostasis, and embryonic development. This study focused on studying the genetic influence of single-nucleotide polymorphisms (SNPs) within the NCOA6 gene on lactation perf...

Holstein and Jersey cows, as excellent dairy breeds, have their own advantages in milk yield, milk quality, disease resistance, and heat resistance. However, the adaptability and rumen microbiome changes in Holstein and Jersey cows under heat stress are not clear. Therefore, the main objective of this study was to compare the differences in heat to...

As global fish consumption rises, improving fish health through immunomodulatory feed ingredients shows promise while also supporting growth performance. This study investigated the effects of yeast prebiotics, probiotics, a postbiotic (butyrate), and black soldier fly larvae (BSFL) meal on fish immune responses. Zebrafish were fed diets containing...

Selenium (Se) is an essential nutrient that has gained attention for its impact on the human immune system. The purpose of this review is to explore Se’s immunomodulatory properties and to make up-to-date information available so novel therapeutic applications may emerge. People acquire Se through dietary ingestion, supplementation, or nanoparticle...

Mycotoxins are toxic metabolites from molds that can contaminate cereal grains in the field and during storage. Pigs are very sensitive to deoxynivalenol (DON) and other Fusarium mycotoxins, and their diets contain high proportions of cereals and fibrous cereal byproducts such as dried distillers grains. This puts them at an increased risk for nega...

Gastrointestinal nematodes (GINs) are a major constraint to the sheep industry. Infected animals can develop clinical signs, like anemia, hypoproteinemia, diarrhea, and in extreme cases death. The misuse of anthelmintics to treat infected animals has led to the development of GIN resistance making necessary the integration of different approaches t...

Selenium (Se) is essential for optimal ovine health and production, and sheep raised on Se-deficient soils can be vulnerable to Se deficiencies that can affect immune function. Organic or inorganic forms of Se supplementation can remedy these consequences. While inorganic Se is less costly, organic Se is more bioavailable and may be more efficient...

Vitamin K (VK) is an essential micronutrient impacting many systems in the body. This lipid-soluble vitamin is found in various plant and animal products and is absorbed via the lymphatic system. This biomolecule’s importance to human health includes but is not limited to its promotion of brain, cardiovascular, bone, and immune functions. These bio...

Background Johne’s disease is a chronic wasting disease caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP). Johne’s disease is highly contagious and MAP infection in dairy cattle can eventually lead to death. With no available treatment for Johne’s disease, genetic selection and improvements in management practices could...

Infections with gastrointestinal nematodes (GINs) reduce the economic efficiency of sheep operations and compromise animal welfare. Understanding the host’s response to GIN infection can help producers identify animals that are naturally resistant to infection. The objective of this study was to characterize the hepatic transcriptome of sheep that...

LncRNAs (Long non-coding RNA) is an RNA molecule with a length more than 200bp. LncRNAs can directly act on mRNA, thus affecting the expression of downstream target genes and proteins, and widely participate in many important physiological and pathological regulation processes of the body. In this study, RNA-Seq was performed to detect lncRNAs from...

Gastrointestinal nematodes (GINs) can be a major constraint and global challenge to the sheep industry. These nematodes infect the small intestine and abomasum of grazing sheep, causing symptoms such as weight loss, diarrhea, hypoproteinemia, and anemia, which can lead to death. The use of anthelmintics to treat infected animals has led to GIN resi...

Despite regulatory elements such as long non - coding RNAs representing most of the transcriptome, the functional understanding of long non - coding RNAs in relation to major health conditions including bovine mastitis is limited. This study examined the milk somatic cell transcriptome from udder quarters of 6 Holstein dairy cows to identify differ...

Pyocyanin (PCN) is an extracellular toxin secreted by Pseudomonas aeruginosa (PA), which has redox capacity and disrupts the redox balance of host cells, affecting cell function and leading to cell death. The aim of this experiment was to compare the degree of apoptosis, inflammation, and oxidative stress of bovine mammary epithelium cells (bMECs)...

Sheep infected with gastrointestinal nematodes (GIN) can show weight loss, anemia, diarrhea, decrease appetite, and hypoproteinemia, which can sometimes lead to death. These signs of infection decrease productivity and cause economic losses. Economic losses can also be associated with treatment without efficacy due to GIN resistance to most anthelm...

Mycotoxins are secondary metabolites produced by a variety of fungi that contaminate animal food and feeds and are capable of inducing a wide range of toxicities. Predictive in vitro models represent valuable substitutes for animal experiments to assess the toxicity of mycotoxins. The complexities of the interactions between epithelial and innate i...

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 f...

As aquaculture production continues to grow, producers are looking for more sustainable methods to promote growth and increase fish health and survival. Butyrate is a short-chain fatty acid (SCFA) with considerable benefits to gut health, and in recent years, butyrate has been commonly used as an alternative to antimicrobials in livestock productio...

The mammary glands, responsible for milk secretion, are regulated at a local level by various hormones, growth factors, non-coding RNAs, and other elements. Recent research has discovered the presence of lncRNAs in these glands, with suggestions that they may be essential for the maintenance and function of mammary glands. Besides directly controll...

Studies are lacking that investigate the dietary nutrient requirements of lake whitefish (Coregonus clupeaformis), a newly farmed fish species in Ontario, Canada. Dietary levels of protein and lipid must be optimized to ensure high growth performance for the commercial success of this species. Additionally, the inclusion of insect meal in the diet...

Our objective was to investigate the effects of dietary supplementation of omega-3 (n3) fatty acids (FA) on physiological responses to lipopolysaccharide (LPS) challenge in early postpartum cows. Healthy cows were blocked by parity and BCS and randomly assigned to 1 of 3 top-dress treatments at 2 d in milk (DIM): 1) unsupplemented control received...

Our objectives were to investigate the changes in fatty acids (FA) composition in peripheral blood plasma and leukocytes (PBL) following an intravenous (IV) infusion of lipopolysaccharide (LPS) in early postpartum cows. At 14 DIM, cows were blocked by parity and BCS and randomly assigned to one of 2 IV infusions: LPS at 0.0625 μg/ kg of BW diluted...

Climate change is a problem that causes many environmental issues that impact the productivity of livestock species. One of the major issues associated with climate change is an increase of the frequency of hot days and heat waves, which increases the risk of heat stress for livestock species. Dairy cattle have been identified as being susceptible...

The rise of multi-omics technology in recent years provides convenient for in-depth study of the pathogenesis of dairy cow mastitis, and circRNAs, as endogenous non-coding RNAs, are expected to become molecular targets to study the pathogenesis of dairy cow mastitis. LPS, as a component of the outer wall of E. coli cell wall, is a common endotoxin...

Mycobacterium avium subsp. Paratuberculosis (MAP) is an intracellular pathogen that causes Johne's disease (JD) in cattle and other ruminants. IL10RA encodes the alpha chain of the IL-10 receptor that binds the cytokine IL-10, and is one of the candidate genes that have been found to be associated with JD infection status. In this study, a previous...

Vitamin D (VD) is a steroid hormone, of which vitamin D3 (VD3) is the main form in fish. Fish obtain VD3 majorly from diets, and VD3 has been widely used in aquatic feed as feed additive. As one of the essential nutrients, VD3 plays an indispensable role in the growth and health of fish. Due to the particularity of the fish living environment, the...

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...

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...

Simple Summary Exposure to microbial stressors has huge implications in terms of animal health and welfare. Bacterial lipopolysaccharide (LPS) is a potent endotoxin, commonly responsible for various livestock pathologies, which impose huge economic losses to the livestock industry. MiRNAs regulate major biological processes and have multiple biolog...

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 were identified and compared between early lactation and non-lactation. After analysis, 10,684 circRNAs were identified, 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...

Simple Summary Milk production traits of cows are important economic indicators of the livestock industry. Many dairy farms strive to improve the quality of their milk. Long-chain acyl-CoA synthetase 1 (ACSL1) is a gene related to lipid metabolism. It is widely found in various organisms and can affect fat content and protein content in milk. Singl...

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...