Exploration of Luteinizing hormone in murrah buffalo (Bubalus bubalis) urine: Extended surge window opens door for estrus prediction

Urinary Cell-Free miR-99a-5p as a Potential Biomarker for Estrus Detection in Buffalo

Accurate estrus detection method is the need of the hour to improve reproductive efficiency of buffaloes in dairy industry, as the currently available estrus detection methods/tools lack high sensitivity and specificity. Recently, circulating miRNAs have been shown as non-invasive biomarkers by various studies. Hence, in order to evaluate their potential as estrus biomarkers, the objective of this study was to identify and compare the levels of 10 hormone-responsive miRNAs in the urine collected at proestrus (PE), estrus (E), and diestrus (DE) phases of buffaloes (n = 3) pertaining to a discovery sample. Among 10 urinary miRNAs, the levels of bta-mir-99a-5p (E/PE 0.5-fold, P < 0.05; DE/PE 1.9-fold), bta-miR-125b (E/PE 0.5-fold; DE/PE 0.7-fold), bta-mir-145 (E/PE 1.5-fold; DE/PE 0.7-fold), bta-mir-210 (E/PE 1.2-fold, DE/PE 0.7-fold), mir-21 (E/PE 1.5-fold, DE/PE 2-fold), and bta-mir-191 (E/PE 1.3-fold; DE/PE 0.8-fold) were found to be altered during different phases of buffalo estrous cycle. In contrast, bta-mir-126-3p, bta-let-7f, bta-mir-16b, and bta-mir-378 were undetected in buffalo urine. Furthermore, a validation study in an independent group of 25 buffalo heifers showed the increased levels of urinary bta-mir-99a-5p during the DE (3.92-fold; P < 0.0001) phase as compared to the E phase. Receiver operating characteristic curve analyses also revealed the ability of urinary miR-99a-5p in distinguishing the E from the DE phase (area under the curve of 0.6464; P < 0.08). In silico analysis further showed an enrichment of miR-99a-5p putative targets in various ovarian signaling pathways, including androgen/estrogen/progesterone biosynthesis and apoptosis signaling, implicating the role of miR-99a-5p in ovarian physiology. In conclusion, significantly lower levels of bta-mir-99a-5p at the E phase than the DE phase in buffalo urine indicate its biomarker potential, which needs to be further explored in a large cohort in the future studies.

Epitope-based in silico peptide design yields peptide-directed antibodies that recognize the buffalo luteinizing hormone

We present a novel peptide sequence identified through in silico epitope design and the later generation of peptide-directed antibodies recognizing the buffalo luteinizing hormone. Peptides and antibodies, specific to reproductive hormones, are valuable tools for developing point-of-care immunodiagnostic tools. The study predicted an epitope peptide in silico from buffalo luteinizing hormone and the generation of polyclonal antibodies against this peptide sequence. In this quest, we identified a novel epitope peptide sequence (luteinizing hormone peptide, LHP) through bioinformatics tools. The peptide was further synthesized and characterized. The polyclonal antibodies (anti-LHP) were raised against the peptide in the rabbit. Thereafter, we explored a strategy for detecting buffalo luteinizing hormone (LH) using the anti-peptide antibodies developed. The affinity of the peptide, bovine lutropin beta, and crude LH (prepared from buffalo pituitary) towards the raised antibodies was established by dot blot and ELISA. Specific recognition of the luteinizing hormone by the raised polyclonal antibodies highlights the ability of the identified peptide (LHP) and developed polyclonal antibodies (anti-LHP) as suitable diagnostic reagents for sensing the buffalo luteinizing hormone. Through this work, we analyzed and translated the "-omics" information in the LH gene sequence for the development of a novel peptide and antibodies as valuable immuno-reagents.

Detection of urinary luteinizing hormone in Japanese black cows after administration of gonadotropin-releasing hormone

The blood luteinizing hormone (LH) surge in cows is well studied. However, little is known about urinary LH in cows. This study examined urinary LH concentrations after administration of gonadotropin-releasing hormone (GnRH) in six Japanese black cows to induce LH secretion from the pituitary gland into the bloodstream. Abrupt rises in plasma and urinary LH were observed after GnRH administration. Plasma and urinary LH peaked at 2 and 5 hr, respectively. A positive correlation was observed between plasma LH concentrations and urinary LH amounts. Ovulation was confirmed in the cows after 48 hr of GnRH administration. These data strongly suggest that urinary LH is derived from plasma LH, which triggers ovulation in cows.

A proof-of-concept of lateral flow based luteinizing hormone detection in urine for ovulation prediction in buffaloes

We present a method for the detection of luteinizing hormone (LH) in buffalo urine by using gold nanoparticles (AuNPs) conjugated with novel anti-peptide antibodies against LH (anti LHP) in lateral flow assay format. Buffalo LH is an important reproductive hormone and is a chemically complex glycoprotein. Its surge release precedes ovulation and therefore detecting LH has implications in identifying the ovulation event. Any sensor thus developed for sensing LH may have the potential for predicting ovulation and hence can assist herd managers in making decisions on the timing of artificial insemination. Recombinant LH production is time consuming, difficult and costly. Hence, we identified an epitope peptide sequence in buffalo LH and raised antibodies against it. The chemically synthesized peptide and antibodies were used for developing the sensor. The gold nanoparticles and conjugates were characterized through physicochemical methods which confirmed the binding of peptides and antibodies to the gold nanoparticles. A qualitative ELISA for sensing LH was developed based on competitive binding of gold nanoparticles conjugated with the epitope peptide and LH towards the anti-peptide antibodies against LH. We also further explored the detection of LH in buffalo urine using the gold nanoparticle-LHP conjugate (AuNP-LHP) in dipstick format. These experiments provided a proof-of-concept towards applicability of the LH based sensor for ovulation prediction in buffaloes.

Detection of estrous biomarkers in the body exudates of Kangayam cattle (Bos indicus) from interplay of hormones and behavioral expressions

Behavioral expressions and biochemical composition of body exudates are significantly altered in concert with the endocrine status, which are all clear indicators of physiological conditions of animals. In this study, we sought to infer about the reproductive physiological status of Kangayam cattle (Bos indicus) by analyzing behaviors, endocrine pattern, and body exudates and further to discover estrous biomarkers so as to facilitate timely artificial insemination/mating and to aid in aspects of conservation of the species. Therefore, in this study, we followed Kangayam cows through pre-estrous to post-estrous phases to correlate the endocrine dependence of biochemical constituents in urine and cervical mucus and sought to identify estrous biomarkers. Behavioral estrus was confirmed in 10 cows, from which urine samples were collected and subjected to determination of LH, FSH, estrogens, progesterone, proteins, and lipids. Furthermore, urinary fatty acids and proteins were profiled using gas chromatography and SDS-PAGE, respectively. The volatile compounds in the urine and cervical mucus were identified by gas chromatography-mass spectrometry analysis. The data revealed that LH, FSH, and estrogen levels increased significantly in estrous urine compared with nonestrous urine, whereas progesterone status was vice versa (P < 0.05). The lipid content was also significantly higher in estrous urine than in pre- and post-estrous urines (P < 0.05). There were also cyclical variations of volatiles and fatty acid profiles across phases of the estrous cycle. More acidic compounds were present in estrous urine, rendering it more acidic, than in pre- and post-estrous urines. Interestingly, oleic acid, which was present as a fatty acid in estrous and post-estrous urines, appeared to be a volatile in post-estrous urine and estrous cervical mucus. In addition, octanoic and butanoic acids were specific to both estrous urine and cervical mucus, indicating their possible candidature as estrous biomarkers. SDS-PAGE analysis showed pronounced expression of a 98 kDa protein in post-estrous urine, which in matrix-assisted laser desorption ionization-time of flight mass spectrometry was identified as albumin. Our results demonstrate multiple biomarkers in estrous urine and specific volatiles in cervical mucus that offer scope to develop viable estrus detection kits for Kangayam cows.

Salivary luteinizing hormone: An open window to detect oestrous period in buffalo

Silent oestrus is an unsurmountable problem in the management of buffalo reproduction. In addressing this issue, we have earlier reported variation in the levels of urinary luteinizing hormone (LH) through the different phases of oestrous cycle with an extended window during the mid-oestrous phase. Based on this report, the present study is designed to assess the salivary LH levels in buffalo during the different phases of oestrous cycle. Bovine LH ELISA kit was used to determine the level of salivary LH. We observed a notable variation in salivary LH levels during the different phases of oestrous cycle. The maximum LH level, 39.07 mIU/ml, observed during oestrus, which was significantly (p < .05) higher than other consecutive phases. Altogether, the results showed a significant (p < .05) fold variation during oestrus compared with other phases. Therefore, the study convincingly shows that salivary LH has the potential of application in development of a modality for non-invasive oestrous detection in buffalo.

A combinatorial model for effective estrus detection in Murrah buffalo

BACKGROUND

Buffaloes are silent heat animals and lacunae in their estrus detection results a substantial economic loss in developing countries. Many advanced tools to aid heat detection have been developed but are neither affordable nor easily interpretable by marginal farmers.

AIM

The present investigation was made to develop a cost-effective estrus detection model by combining several known estrus predicting parameters.

MATERIALS AND METHODS

Various signs of estrus were classified under major parameters such as visual, cow behavioral, bull behavioral, biochemical, and gyneco-clinical. Expression of those parameters was observed in buffaloes, and the percentage of positive estrus detection was calculated for each combination of estrus prediction parameters.

RESULTS

The present result concludes that the model comprises of five parameters group with several signals with twenty-six different combinations. It was observed that the expression of individual combinations and their corresponding estrus detection efficiency varies significantly, i.e., detection efficiency rises as the number of combination increases.

CONCLUSION

Combination of three parameters would provide an estrus detection efficiency >70% and suggested for an easy estrus detection. This would be a cost-effective model for farmers and benefits in enhancing buffalo population/reproduction.

p-cresol and oleic acid as reliable biomarkers of estrus: evidence from synchronized Murrah buffaloes

Successful reproductive management in buffaloes depends on effective estrus detection. Urinary pheromones identified from natural estrous cycle have been reported to decipher estrus phase. However, its presence has not been analyzed in the urine after synchronization. Thus, our present investigation was to investigate the influence of synchronized estrus urine in bulls and to examine the presence of estrus-specific compounds ascertained in natural estrus in synchronized buffaloes. Mid-stream urine was collected from six synchronized buffaloes during various phases of estrous cycle and volatiles were examined using GC-MS. Sexual provocation in bulls was established by displaying persistent flehmen and frequent mounting towards estrus urine from synchronized animals. Totally forty-two volatile compounds were identified from three phases of estrous cycle, more specifically 4-methyl phenol (p-cresol) and 9-octadecenoic acid (oleic acid) in estrus urine of synchronized animal as similar to natural estrus. Hence, these chemical cues in buffalo urine might be employed as potential marker candidates for the development of an estrus detection aid.