The Cytogenetics of the Water Buffalo: A Review

The water buffalo (Bubalus bubalis), also known as the Asian buffalo, is an essential domestic bovid. Indeed, although its world population (~209 million heads) is approximately one-ninth that of cattle, the management of this species involves a larger human population than that involved with raising cattle. Compared with cattle, water buffalo have been understudied for many years, but interest in this species has been increasing, especially considering that the world population of these bovids grows every year—particularly that of the river buffalo. There are two genera of buffalo worldwide: the Syncerus (from the African continent), and the Bubalus (from the southwest Asian continent, Mediterranean area, southern America, and Australia). All species belonging to these two genera have specific chromosome numbers and shapes. Because of such features, the study of chromosomes is a fascinating biological basis for differentiating various species (and hybrids) of buffaloes and characterizing their karyotypes in evolutionary, clinical, and molecular studies. In this review, we report an update on essential cytogenetic studies in which various buffalo species were described from evolutionary, clinical, and molecular perspectives—particularly considering the river buffalo (Bubalus bubalis 2n = 50). In addition, we show new data on swamp buffalo chromosomes.

Molecular cloning, functional characterization, tissue expression and polymorphism analysis of buffalo PRDX6 gene

PRDX6 is a bifunctional protein involved in antioxidant regulation and phospholipid metabolism. Previous studies have shown that PRDX6 is involved in some biological pathways and networks related to lactation. The aim of this study was to explore the characteristics, function, tissue expression and variation of buffalo PRDX6 gene. We cloned and characterized the complete coding sequence (CDS) of buffalo PRDX6. The CDS of PRDX6 for swamp and river buffalo is the same, which consists of 675 nucleotides and encodes a protein of 224 amino acids. Buffalo PRDX6 contains one PRX_1cys functional domain (AA 7–222), which is probably related to the regulation of oxidative stress. Multi-tissue differential expression analysis showed that buffalo PRDX6 was highly expressed in the muscle, brain, lung and small intestine during non-lactation and lactation, and there were significant differences in expression in all the tissues except the small intestine between the two periods. It is worth noting that the mRNA abundance of buffalo PRDX6 in non-lactating mammary gland is higher than that in lactating mammary gland. Among the two single nucleotide polymorphisms (SNPs) identified in the CDS in this study, c.261C>T is shared by the two types of buffalo with different allelic frequencies, and c.426T>G is found only in river buffalo. The c.426T>G is non-synonymous, resulting in the amino acid substitution p.Asn142Lys. Only one nucleotide differential site is identified in PRDX6 gene between buffalo and other species of Bovidae. Phylogenetic analysis indicated that buffalo PRDX6 has a closer genetic relationship with that of the species in Bovidae. These results indicate that PRDX6 probably plays a crucial role in the mammary gland of buffalo. This study provides the foundation for further functional studies of PRDX6 in buffalo.

Molecular cloning, functional characterization, tissue expression and polymorphism analysis of buffalo PRDX6 gene

PRDX6 is a bifunctional protein involved in antioxidant regulation and phospholipid metabolism. Previous studies have shown that PRDX6 is involved in some biological pathways and networks related to lactation. The aim of this study was to explore the characteristics, function, tissue expression and variation of buffalo PRDX6 gene. We cloned and characterized the complete coding sequence (CDS) of buffalo PRDX6. The CDS of PRDX6 for swamp and river buffalo is the same, which consists of 675 nucleotides and encodes a protein of 224 amino acids. Buffalo PRDX6 contains one PRX_1cys functional domain (AA 7–222), which is probably related to the regulation of oxidative stress. Multi-tissue differential expression analysis showed that buffalo PRDX6 was highly expressed in the muscle, brain, lung and small intestine during non-lactation and lactation, and there were significant differences in expression in all the tissues except the small intestine between the two periods. It is worth noting that the mRNA abundance of buffalo PRDX6 in non-lactating mammary gland is higher than that in lactating mammary gland. Among the two single nucleotide polymorphisms (SNPs) identified in the CDS in this study, c.261C>T is shared by the two types of buffalo with different allelic frequencies, and c.426T>G is found only in river buffalo. The c.426T>G is non-synonymous, resulting in the amino acid substitution p.Asn142Lys. Only one nucleotide differential site is identified in PRDX6 gene between buffalo and other species of Bovidae. Phylogenetic analysis indicated that buffalo PRDX6 has a closer genetic relationship with that of the species in Bovidae. These results indicate that PRDX6 probably plays a crucial role in the mammary gland of buffalo. This study provides the foundation for further functional studies of PRDX6 in buffalo.

A Study on the Transcriptional Profile of NOS2 and IFN-γ Genes in River Buffalo with Endometritis

Background and Aim: Uterine lumen contamination with bacteria is ubiquitous in buffalo after parturition. Nearly one-third of these infected animals develop endometritis which leads to reduced fertility. The present study aimed to evaluate the expressions of IFN-γ and NOS2 genes in uterine tissue of buffaloes with endometritis and comparing them with those in healthy animals using RT-qPCR Materials and Methods: Uterine samples were collected from 50 apparently healthy and 50 clinically infected buffaloes. RNA was extracted from the collected buffalo's uteri and cDNA was synthesized from extracted RNA. Quantitative Real Time PCR technique was performed using this synthesized cDNA. Results: Apparent up-regulation of both genes mRNA expression was recorded in endometritis-infected animals with 8.3-folds for IFN-γ and 9.99-folds for NOS2 (P<0.001). Conclusion: The upregulation of IFN-γ and NOS2 expression in the uterine tissue of endometritis-infected buffaloes can be used as a scale for measuring the efficiency of drugs used for endometritis treatment.

Evolutionary Analysis of OAT Gene Family in River and Swamp Buffalo: Potential Role of SLCO3A1 Gene in Milk Performance

The organic anion transporter (OAT) family is the subfamily of the solute carrier (SLC) superfamily, which plays a vital role in regulating essential nutrients in milk. However, little is known about the members’ identification, evolutionary basis, and function characteristics of OAT genes associated with milk performance in buffalo. Comparative genomic analyses were performed to identify the potential role of buffalo OAT genes in milk performance in this study. The results showed that a total of 10 and 7 OAT genes were identified in river buffalo and swamp buffalo, respectively. These sequences clustered into three groups based on their phylogenetic relationship and had similar motif patterns and gene structures in the same groups. Moreover, the river-specific expansions and homologous loss of OAT genes occurred in the two buffalo subspecies during the evolutionary process. Notably, the duplicated SLCO3A1 gene specific to river buffalo showed higher expression level in mammary gland tissue than that of swamp buffalo. These findings highlight some promising candidate genes that could be potentially utilized to accelerate the genetic progress in buffalo breeding programs. However, the identified candidate genes require further validation in a larger cohort for use in the genomic selection of buffalo for milk production.

Clinical Applications and Factors Involved in Validating Thermal Windows Used in Infrared Thermography in Cattle and River Buffalo to Assess Health and Productivity

Infrared thermography (IRT) is a non-ionizing, non-invasive technique that permits evaluating the comfort levels of animals, a topic of concern due to the growing interest in determining the state of health and welfare of production animals. The operating principle of IRT is detecting the heat irradiated in anatomical regions characterized by a high density of near-surface blood vessels that can regulate temperature gain or loss from/to the environment by modifying blood flow. This is essential for understanding the various vascular thermoregulation mechanisms of different species, such as rodents and ruminants’ tails. The usefulness of ocular, nasal, and vulvar thermal windows in the orbital (regio orbitalis), nasal (regio nasalis), and urogenital (regio urogenitalis) regions, respectively, has been demonstrated in cattle. However, recent evidence for the river buffalo has detected discrepancies in the data gathered from distinct thermal regions in these large ruminants, suggesting a limited sensitivity and specificity when used with this species due to various factors: the presence of hair, ambient temperature, and anatomical features, such as skin thickness and variations in blood supplies to different regions. In this review, a literature search was conducted in Scopus, Web of Science, ScienceDirect, and PubMed, using keyword combinations that included “infrared thermography”, “water buffalo”, “river buffalo” “thermoregulation”, “microvascular changes”, “lacrimal caruncle”, “udder”, “mastitis”, and “nostril”. We discuss recent findings on four thermal windows—the orbital and nasal regions, mammary gland in the udder region (regio uberis), and vulvar in the urogenital region (regio urogenitalis)—to elucidate the factors that modulate and intervene in validating thermal windows and interpreting the information they provide, as it relates to the clinical usefulness of IRT for cattle (Bos) and the river buffalo (Bubalus bubalis).

Current Knowledge on River Buffalo Meat: A Critical Analysis

The estimated world population of water buffalo counts around 204 million head, mostly reared for milk production. However, buffaloes also largely contribute to the meat sector, with around 4.3 million tonnes produced in 2019, mainly derived from old animals at the end of their productive or working life and only to a small extent from young animals. Therefore, buffalo meat production has been generally considered unsatisfactory for both quantity and quality. In fact, the dressing percentage is generally lower than 50% and the meat is considered of poor quality mainly due to its dark colour and reduced tenderness. However, in recent years, the healthy properties highlighted by some studies have led to a renewed interest in buffalo meat, with a parallel increase in research. Therefore, this review aims at providing an updated picture on carcass and meat quality traits in river buffalo, with special attention to the intrinsic and extrinsic factors contributing to their variability. The research done so far has demonstrated that river buffaloes can efficiently contribute to the quanti-qualitative production of meat, provided that the meat supply chain is specifically organised for this purpose. The analysis of the available data also showed that further research is needed on the factors affecting meat production in order to gain greater knowledge essential for planning more targeted interventions.