Summer Anoestrus in Buffalo - A Review

Administration of melatonin prior to modified synchronization protocol improves the productive and reproductive efficiency of Chinese crossbred buffaloes in low breeding season

Introduction

Melatonin is a neurohormone involving various biological processes, including restoration of cyclicity in animals with seasonal breeding patterns. The use of melatonin in different forms has gained broader acceptance in different species, particularly in summer anestrous buffaloes.

Objectives

The objective of the current study was to evaluate the melatonin effect on the reproductive and productive performance of crossbred buffaloes during the low breeding season.

Methods

Sixty-five cyclic and reproductively sound crossbred buffaloes were randomly allocated to three groups: the G1 (n = 20) served as the control group and received no single melatonin, G2 received melatonin (n = 22; 18 mg/50 kg, body weight) once prior to synchronization and G3 group was administered multiple melatonin injections (n = 23; 6 mg/50 kg body weight) for three consecutive days before the start of the synchronization protocol. The reproductive performance, milk yield traits, and serum immunoglobulin M (IgM) and melatonin levels were evaluated in treated and untreated crossbred buffaloes.

Results

The results revealed that a single dose of melatonin administration has (p < 0.05) improved estrus response, ovulation occurrence and follicular growth in crossbred buffaloes compared to control groups. Higher pregnancy rates were observed in both melatonin-treated buffalo groups compared to the control. Following the administration of melatonin, serum IgM level increased in G2 and G3; however, an increment in melatonin level (p < 0.05) was detected in the G2 group only as compared to the control group subsequent day of melatonin administration. The milk compositions were not affected by melatonin administration except for milk urea nitrogen and somatic cell count (SCC). The melatonin administration (p < 0.05) decreased the somatic cell count in buffalo milk compared to untreated.

Conclusion

In conclusion, single or multiple doses of melatonin before initiating the synchronization protocol improved the ovulation, ovulatory follicle diameter and pregnancy rates in crossbred buffaloes during the low breeding season. Moreover, the administration of melatonin enhanced the IgM values along milk traits in terms of milk protein, MUN and somatic cell count in treated buffaloes.

Comparative analysis of biochemical, hormonal, and mineral compositions of preovulatory and cystic ovarian follicles in buffalo during the non-breeding season

This study is a comparative analysis of the biochemical, hormonal, and mineral compositions of follicular fluid in preovulatory and cystic follicles of water buffalo (Bubalus bubalis). In total, reproductive tracts from 215 buffalo along with intact ovaries were collected randomly from an abattoir. The incidence of cystic conditions found in this study was 3.72% (8/215), involving the right ovary in 62.5% of instances and the left ovary in 37.5% of instances during the non-breeding season. Follicular fluid was aspirated from preovulatory follicles (12-15 mm diameter, oestrogen-active, follicular phase or stage IV corpus luteum on one of the two ovaries, n = 10) and cystic follicles (at least 20 mm diameter, no corpus luteum on any one of the two ovaries, n = 8). The follicular fluid samples were assayed for biochemical components (uric acid, creatinine, blood urea nitrogen, cholesterol, total protein, glucose, ascorbic acid, and alkaline phosphatase), hormones (progesterone, estradiol, and insulin), and minerals (calcium, magnesium, phosphorus, copper, zinc, and cobalt). Cystic follicles had greater (P < 0.05) concentrations of creatinine, blood urea nitrogen, cholesterol, progesterone, copper, zinc, and cobalt, and lesser (P < 0.05) concentrations of uric acid, glucose, ascorbic acid, estradiol, insulin, calcium, magnesium, and phosphorus compared with preovulatory follicles. These results indicated the marked differences in follicular fluid composition between preovulatory and cystic follicles in buffalo. Some of the changes were indicative of oxidative stress and disturbed steroidogenesis, two important mechanisms shown to be associated with cystic ovarian disease in various species. Further studies are warranted to investigate whether these differences are directly or indirectly involved in the formation of cystic follicles or are mere manifestations of the condition.

The Impact of Heat Stress on Immune Status of Dairy Cattle and Strategies to Ameliorate the Negative Effects

Heat stress (HS) is well known to influence animal health and livestock productivity negatively. Heat stress is a multi-billion-dollar global problem. It impairs animal performance during summer when animals are exposed to high ambient temperatures, direct and indirect solar radiations, and humidity. While significant developments have been achieved over the last few decades to mitigate the negative impact of HS, such as physical modification of the environment to protect the animals from direct heat, HS remains a significant challenge for the dairy industry compromising dairy cattle health and welfare. In such a scenario, it is essential to have a thorough understanding of how the immune system of dairy cattle responds to HS and identify the variable responses among the animals. This understanding could help to identify heat-resilient dairy animals for breeding and may lead to the development of climate resilient breeds in the future to support sustainable dairy cattle production. There are sufficient data demonstrating the impact of increased temperature and humidity on endocrine responses to HS in dairy cattle, especially changes in concentration of hormones like prolactin and cortisol, which also provide an indication of the likely im-pact on the immune system. In this paper, we review the recent research on the impact of HS on immunity of calves during early life to adult lactating and dry cows. Additionally, different strategies for amelioration of negative effects of HS have been presented.

Reproduction and Fertility of Buffaloes in Nepal

Water buffalo (Bubalus bubalis) in Nepal contributes 57% of the total milk and 36% of the total meat production in the country. The productive efficiency of Nepalese buffaloes is quite low, due mainly to subfertility and infertility. Delayed puberty and prolonged inter-calving intervals, attributed mainly by anestrus due to silent cyclicity and ovarian acyclicity, are the major forms of infertility in Nepalese buffaloes. Moreover, buffaloes in Nepal show a distinct seasonal breeding pattern, with July to December as the active breeding season, and with April to June and January to March as the low and transitional breeding seasons, respectively. Endoparasitic infection and poor nutritional status, which are more severe during the low season, are found to be the major factors causing anestrus and compromising its treatment response in buffaloes. Various hormonal protocols for timed artificial insemination (TAI) have been attempted, with a varying pregnancy outcome. Recently, an integrated technique including anthelmintic treatment, nutritional supplementation and hormone-based fertility management programs for TAI has been developed and implemented successfully. A wider adoption of this technique as a package of practices could be key to improving the reproductive efficiency of buffaloes in Nepal.

Pregnancies following Protocols for Repetitive Synchronization of Ovulation in Primiparous Buffaloes in Different Seasons

Simple Summary

Artificial Insemination (AI) is mainly used after estrus synchronization in buffalo, and consecutive synchronization protocols are used to enhance reproductive efficiency. In this study, two different synchronization protocols have been used: Ovsynch vs. a P₄-administration, and their efficiency in primiparous animals has been evaluated in different seasons for up to four cycles of re-synchronization protocols. Results show that the pregnancy rate upon the initial AI tends to be higher in P₄ treated buffaloes, and that AI efficiency after re-synchronization through P₄ is higher than the Ovsynch protocol. In conclusion, synchronization treatments must be selected according to the season of the year. The results derived from this study could be useful for buffalo breeders who want to improve the reproductive efficiency in primiparous animals in commercially managed buffalo herds.

Abstract

Primiparous buffaloes were tested in two periods of the year characterized, by either low or high reproductive efficiency. They were subjected to two protocols for synchronization of ovulation: (i) Ovsynch (OV) and (ii) progesterone based (P₄) treatment. After calving, the animals underwent a series of four cycles of re-synchronization protocols. The season did not affect pregnancy rates when the results of the two treatments were pooled together with regard to the first synchronization protocol, followed by AI. Pregnancy rates were similar during the low breeding season (50.3% vs. 57.4% in OV and P₄, respectively), but different during the high breeding season (50.4% vs. 67.7% in OV and P₄, respectively; p = 0.000). Logistic regression confirmed a significant effect of treatment and season interaction on pregnancy (p = 0.003). Following re-synchronization, a treatment by season interaction was detected during the low breeding season (odds ratio = 2.233), in favor of P₄. Finally, a survival analysis showed a better response of animals subjected to P₄ treatment from the second AI onward. In conclusion, the pooled data of pregnancy rates from both treatments between seasons are not different following AIs. Better results, though, were obtained from the implementation of P₄ treatment, and are recorded in a season-fashioned mode when the comparison is made following first or cumulative AIs.

Use of GnRH Treatment Based on Pregnancy-Associated Glyco-Proteins (PAGs) Levels as a Strategy for the Maintenance of Pregnancy in Buffalo Cows: A Field Study

The aim of the study was to evaluate the effects of GnRH administrated at day 35 after artificial insemination (AI) on the reproductive performance of buffalo cows. In ten buffalo farms in the period January−February, 481 buffalo cows were subjected to estrus synchronization protocol and fixed-time artificial insemination (Ovsynch−TAI program). Radioimmunoassays (RIA) for pregnancy-associated glycoproteins (PAGs) were used to detect pregnancy at day 28 after AI (cut-off value: ≥1 ng/mL). Among pregnant subjects, those with PAG values between 1 and 2.5 ng/mL were considered at risk of embryonic mortality (EM) and were assigned into two groups: treated (T; n = 57) control (C; n = 57). Treated buffaloes received 0.01 mg of buserelin acetate intramuscularly on day 35 after AI, whereas control buffaloes received no treatment. The pregnancy diagnosis was confirmed at day 60 through PAGs level and rectal palpation. The treatment with GnRH had a significant effect (p < 0.001) in reducing EM. Between days 28 and 60 after AI, the animals that experienced EM were only 2/57 in the T group, while were 13/57 in the C group. Moreover, GnRH treatment produced a significant increase (p < 0.001) in the PAG concentration between day 28 and day 60. Administration of GnRH at day 35 after AI in animals considered at risk of low embryo survival based on PAG levels allowed a reduction in pregnancy losses and improved the pregnancy rate during low-breeding season in buffalo.

Genomic analysis of arginine vasopressin gene in riverine buffalo reveals its potential association with silent estrus behavior

BACKGROUND

Poor estrus expression behavior causes suboptimal reproductive efficiency through poor conception rate. Various signaling pathways are involved in estrus expression but arginine vasopressin (AVP) gene with oxytocin predominantly regulates estrus behavior. This study aimed to perform genomic characterization and evolutionary dynamics of AVP gene through association testing of the novel polymorphic loci and comparative genomic analysis to explore the potential effect of AVP gene on estrus behavior of Nili-Ravi buffaloes.

METHODS AND RESULTS

198 Nili-Ravi buffaloes were screened for the quest of novel polymorphism in the AVP gene. In exon-1, five polymorphic sites were detected including deletion of two (c.47delA and c.57delA) nucleotides that caused drastic variation in subsequent amino acid sequence due to frame shift including functional short peptide of nine residues. The 3-D structure revealed a loss of transmembrane loop between 16 and 31 residues in Nili-Ravi buffalo AVP protein sequence, suggesting that missing loop apparently reduced the gene functionality in Nili-Ravi buffalo by inhibiting cellular reactions and muting the animal estrus cyclicity. Three polymorphisms detected in AVP gene were significantly associated with silent estrus (P < 0.05). The comparative genomic analysis revealed that AVP gene is present on chromosome 14 having one conserved motif (Neurohypophysial) in buffalo.

CONCLUSIONS

This study suggested the potential use of polymorphic sites as promising genetic markers for selection of buffaloes with pronounced estrus expression.

Comparative Proteome Profiling of Saliva Between Estrus and Non-Estrus Stages by Employing Label-Free Quantitation (LFQ) and Tandem Mass Tag (TMT)-LC-MS/MS Analysis: An Approach for Estrus Biomarker Identification in Bubalus bubalis

Accurate determination of estrus is essentially required for efficient reproduction management of farm animals. Buffalo is a shy breeder and does not manifest overt signs of estrus that make estrus detection difficult resulting in a poor conception rate. Therefore, identifying estrus biomarkers in easily accessible biofluid such as saliva is of utmost interest. In the current study, we generated saliva proteome profiles during proestrus (PE), estrus (E), metestrus (ME), and diestrus (DE) stages of the buffalo estrous cycle using both label-free quantitation (LFQ) and labeled (TMT) quantitation and mass spectrometry analysis. A total of 520 proteins were identified as DEPs in LFQ; among these, 59 and four proteins were upregulated (FC ≥ 1.5) and downregulated (FC ≤ 0.5) during E vs. PE, ME, and DE comparisons, respectively. Similarly, TMT-LC-MS/MS analysis identified 369 DEPs; among these, 74 and 73 proteins were upregulated and downregulated during E vs. PE, ME, and DE stages, respectively. Functional annotations of GO terms showed enrichment of glycolysis, pyruvate metabolism, endopeptidase inhibitor activity, salivary secretion, innate immune response, calcium ion binding, oocyte meiosis, and estrogen signaling. Over-expression of SERPINB1, HSPA1A, VMO1, SDF4, LCN1, OBP, and ENO3 proteins during estrus was further confirmed by Western blotting. This is the first comprehensive report on differential proteome analysis of buffalo saliva between estrus and non-estrus stages. This study generated an important panel of candidate proteins that may be considered buffalo estrus biomarkers which can be applied in the development of a diagnostic kit for estrus detection in buffalo.

Cell adhesion and immune response, two main functions altered in the transcriptome of seasonally regressed testes of two mammalian species

In species with seasonal breeding, male specimens undergo substantial testicular regression during the nonbreeding period of the year. However, the molecular mechanisms that control this biological process are largely unknown. Here, we report a transcriptomic analysis on the Iberian mole, Talpa occidentalis, in which the desquamation of live, nonapoptotic germ cells is the major cellular event responsible for testis regression. By comparing testes at different reproductive states (active, regressing, and inactive), we demonstrate that the molecular pathways controlling the cell adhesion function in the seminiferous epithelium, such as the MAPK, ERK, and TGF-β signaling, are altered during the regression process. In addition, inactive testes display a global upregulation of genes associated with immune response, indicating a selective loss of the "immune privilege" that normally operates in sexually active testes. Interspecies comparative analyses using analogous data from the Mediterranean pine vole, a rodent species where testis regression is controlled by halting meiosis entry, revealed a common gene expression signature in the regressed testes of these two evolutionary distant species. Our study advances in the knowledge of the molecular mechanisms associated to gonadal seasonal breeding, highlighting the existence of a conserved transcriptional program of testis involution across mammalian clades.

Influence of Days after Calving and Thermal Stress on the Efficacy of a Progesterone-Based Treatment in Acyclic Italian Mediterranean Buffalo

Simple Summary

“Mozzarella di Bufala Campana DOP” (mozzarella cheese) is mainly produced and marketed during the spring and summer months. The buffalo is a seasonal species that increases its reproductive activity when daylight hours decrease. Therefore, to increase milk production in the favourable period, the so-called “Out of Breeding Season Mating” technique is applied. It consists of the interruption of sexual promiscuity during the naturally occurring breeding season and concentrating calving and milk production during periods of increasing daylight length. However, the application of this technique increases the incidence of anoestrus, as animals are forced to breed outside of their natural and favoured period of the year, although other factors can also increase the incidence of anoestrus, such as climate. A reduction of seasonal anoestrus can be achieved by using some hormonal treatments. In this study, primiparous acyclic buffaloes were selected and divided into three classes according to their days in milk. Animals were synchronized using P₄ vaginal implants, and artificial insemination (AI) was performed according to protocol. The temperature–humidity index (THI) was recorded to evaluate its influence on anoestrus. Statistical analysis showed that the implemented P₄-based treatments were highly effective in removing the anoestrus condition in buffaloes. On the contrary, no influence of the THI on the efficacy of the P₄ synchronization treatment was observed.

Abstract

The aim of this study was to evaluate the efficacy of a progesterone-based treatment on anoestrus in buffaloes. Primiparous acyclic buffaloes (n = 276), were divided into three classes according to their days in milk (DIM): from 50 to 90 (Class I; n = 86), from 91 to 150 (Class II; n = 102) and from 150 to 200 (Class III; n = 88). Animals were synchronized using P₄ vaginal implants, followed by timed artificial insemination (TAI). They were then allowed to enter into a larger group of buffaloes for natural mating 15 days after AI was performed, and pregnancy status was monitored from then on at 15-day intervals. Finally, the temperature–humidity index (THI) was calculated. Statistical analysis was performed by ANOVA by means and both multiple and linear regression. The total pregnancy rate (PR) was 87.7%, with no differences among DIM classes (88.0, 92.4, and 80.0% in Classes I, II, and III, respectively). However, the PR at TAI tended to be higher (p = 0.07) in buffaloes in Class II. The follicle (FL) area in Class II buffaloes was larger (p < 0.01) than that of the other classes. No influence of the THI on the total PR was recorded. The pregnancy outcome at TAI was affected by the FL area (odds ratio = 2.237; p < 0.05) and body condition score (BCS) (odds ratio = 1.256; p < 0.05). In conclusion, treatment with vaginal P₄ optimizes pregnancy rates in anoestrus buffaloes, particularly when the animals are in mid-lactation and show an optimal BCS. Furthermore, the THI does not seem to affect the efficiency of the progesterone treatment.

Effects of age and season on conception rate of Mediterranean Italian Dairy Buffalo (Bubalus bubalis) following oestrus synchronization and fixed-time artificial insemination

The objective of this project was to report the effects of season and age on conception rate amongst Italian Mediterranean Buffalo subjected to an Ovsynch/Resynch (O/R) reproductive management protocol. The study utilized nulliparous (heifers), primiparous buffalo cows (PBC) and multiparous buffalo cows (MBC). The primiparous and multiparous groups were subjected to the synchronization protocol throughout the entire year, but heifers were synchronized and inseminated only during the spring/summer seasons. The conception rate obtained following the OvSynch oestrus synchronization protocol, applied during spring, was 68.4% for heifers, 83.3% for PBC and 67.7% for MBC. The overall total conception rates following the complete O/R protocol were 84.27%, 94.4% and 79%. Conception rates achieved during summer were heifers 52%, PBC 47.2% and MBC 49%, whilst overall conception rates following the full O/R protocol were 72%, 69.8% and 58.2% respectively. In the autumn seasons, PBC conceived 58.9% and MBC 52.1% following initial Ovsynch, which improved to total overall conception rates of 87.5% and 78.7% following the full O/R protocol. Similarly, in the winter season, PBC experienced a conception rate of 47.5% following Ovsynch and 72.5% after a follow-up Resynch. MBC experienced 60.0% and 74.4% conception following Ovsynch and full O/R, respectively, during winter. Total conception rates during all seasons were quite acceptable following the O/R protocol. There was a significant decrease from spring to summer in conception rate for all parity groups, but heifers were not a severely affected as older buffalo cows. This finding agrees with that of other investigators indicating that heifer fertility is not as negatively impacted by long photoperiod and higher ambient temperature as that of older animals. The O/R protocol as utilized in this study is an effective means of reproductive management for dairy buffalo cows and is effective for improving fertility during out-of-season breeding.

Effect of exogenous administration of oxytocin on postpartum follicular dynamics, oestrous rate and ovulation in Nili-Ravi buffaloes

Based on different surveys, dairy farmers are concerned about extensive use of exogenous oxytocin in buffaloes, which is being held responsible for reproductive problems including irregular oestrous cycle and delayed ovulation. For these concerns, effects of oxytocin injection on postpartum follicular dynamics, postpartum oestrous interval (PEI), oestrous length, the interval from onset of estrus to ovulation and blood progesterone (P4) were studied in Nili-Ravi buffaloes. For this purpose, 23 animals within 1 week after calving were randomly divided into three groups: without oxytocin (CON; n = 7), 10 i.u. oxytocin (LOW; n = 8), 30 i.u. oxytocin - (HIGH; n = 8) and used to record the PEI for the study period of 154 days. At subsequent estrus, three buffaloes from each group (not served) were selected randomly to monitor two cycles for 6 weeks. Transrectal ultrasonography was performed to evaluate follicular and corpus luteum (CL) development, and blood sampling was done for progesterone (P4) analysis. These results revealed that postpartum oestrous interval (PEI) decreased significantly in oxytocin-treated groups. The number of small, medium and total follicles on the left ovary was significantly higher in the HIGH group. However, an overall number of small and total follicles on both right and left ovaries was significantly higher in CON and HIGH groups. On the other hand, there was no difference in the number of follicles on the right ovary among all treatment groups. The same was true for the size of pre-ovulatory follicles, CL, P4 concentrations and oestrous cycle length. The intervals from onset of estrus to ovulation and from standing estrus to ovulation were increased considerably in the HIGH group. It is concluded that exogenous oxytocin administration resulted in the shortening of PEI but triggered a delay in ovulation. Moreover, a higher dose of oxytocin could stimulate the growth of small, medium, and total follicles in postpartum Nili-Ravi buffaloes.

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).

Reproductive seasonality influences oocyte retrieval and embryonic competence but not uterine receptivity in buffaloes

Since buffaloes are a seasonal, polyestrous species, optimizing reproduction during the non-breeding season is a key factor in increasing the reproductive and productive efficiency of herds. Ovum pick-up associated with in vitro embryo production and embryo cryopreservation is an alternative to reduce seasonal impacts. We studied the effects of seasonality in buffalo oocyte donors and embryo recipients during the favorable and non-favorable breeding seasons. Donors were evaluated for oocyte recovery and blastocyst production rate as dFBS (donors in favorable breeding season) or dNBS (donors in non-favorable breeding season). Embryos produced from dFBS or dNBS were cryopreserved by vitrification or the slow-freeze method for direct transfer and transferred to recipients in the favorable (rFBS) or non-favorable breeding season (rNBS). The heifers or cows were subjected to a fixed-time embryo transfer protocol and conception rates were determined on day 30 and on day 60. The oocyte recovery was lower in dFBS than in dNBS (7.6 vs. 10.0 oocyte/OPU, p = 0.0262); while no difference was found comparing blastocyst production rate (23.7% vs. 30.9% of blastocysts, respectively). Embryos from dFBS resulted in greater (p = 0.0013) conception rates on day 30 compared to dNBS (46.5% vs. 22.4%, respectively), despite the breeding season. The rFBS and rNBS treatments had similar (p = 0.6714) conception rates on day 30 (38.0% vs. 33.0%, respectively), indicating similar uterine receptivity. However, heifers on FBS had higher (p = 0.0003) conception rates on day 30 than cows (73.9% vs. 13.3%, respectively) when receiving embryos from dFBS. Vitrification and direct transfer had similar (p = 0.1698) conception rates on day 30 (30.4% vs. 41.4%, respectively). In conclusion, in vitro-produced embryos derived from dFBS were more competent in establishing pregnancy than dNBS counterparts, independent of recipients' reproductive seasonality. Heifers achieved better conception rates than cows during the favorable breeding season when the embryo came from dFBS. Cryopreserved in vitro produced embryos represent a reliable alternative to reduce seasonal variations in buffalo reproduction. The data elucidate the seasonal effects on embryo competence and on recipients' uterine receptivity, affording new strategies to implement ovum pick-up associated with in vitro embryo production programs in buffalo herds.

Seasonal patterns of reproduction and production in Nili-Ravi buffaloes

Records of Nili-Ravi buffalo maintained at ICAR-Central Institute for Research on Buffaloes, sub-campus Nabha for the period 2009–2018, were analysed with the aim to study the effect of season on various reproductive and productive parameters. Seasons were categorized as follows: winter –Nov. to Feb.; summer – Mar. to Jun.; and rainy – Jul. to Oct. The average temperature ranged from as high as 32.3°C in summer to as low as 18.4°C in winter. The average humidity ranged from as low as 28.2% in summer to as high as 52.8% in rainy season. Data of 4,203 estruses during this period revealed significant effect on estrus expression with lower expression in summer, and highest during winter. A significant reduction in estrus detection efficiency during summer and rainy seasons as compared to winter was recorded. The conception rate was significantly higher during winter as compared to summer and rainy season. During this period, 1,398 calvings were recorded. It was observed that buffaloes that calved in summer tended to have highest calving to first service interval as well as service period (135 and 167 d, respectively) and lowest in rainy season (78 and 114 d, respectively). The wet and herd averages were significantly higher in winter as compared to summer and rainy. Animals that calved in rainy season had significantly lower lactation length (299±13 d) as compared to summer (373±13 d) and winter (320±17 d). It may be concluded that high temperature and humidity during summer and rainy season exert negative effect on reproductive and productive performance in Nili-Ravi buffaloes.

Seasonality and photoperiod influence in vitro production of buffalo embryos

Buffalo is considered short-day breeder in tropical and subtropical part of the world and seasonality and photoperiodism impart major influence on its fertility. However, its impact on in vitro embryo production (IVEP) remains elusive. Therefore, this study investigated the effect of seasonal variations and photoperiodism on morphological and molecular parameters of IVEP in buffalo. For this purpose, we conducted two different experiments on the oocytes obtained by aspirating follicles from abattoir derived ovaries. In Exp. I, retrospective analysis was performed for oocyte recovery, blastocyst and hatching rate, during four consecutive seasonal periods (i.e. January-March, April-June, July-September and October-December). In Exp. II, oocytes from peak breeding and non-breeding seasons were subjected to 24 hr in vitro maturation and evaluated for polar body extrusion to assess maturation rate. Results showed that embryo development was markedly low during second quarter (April-June) and maximum during fourth quarter (October-December) of the year; referred as non-breeding and breeding seasons, respectively. Comparative data analysis demonstrated that poor oocyte quality is major reason for lesser efficiency of embryo production during non-breeding season than peak breeding season as suggested by poor oocyte recovery (2.31 ± 0.10 vs. 3.65 ± 0.27) and maturation rate (33.32 ± 2.1 vs. 63.15 ± 7.31). Subsequently, comparative gene expression analysis of blastocysts during peak breeding season significantly upregulated pluripotency gene (OCT-4) and downregulated heat shock protein 90, as compared to non-breeding season. Therefore, it could be divulged from the present study that seasonal variations and photoperiodism have profound effect on oocyte quality and subsequent embryo development. It is recommended to find suitable additives for in vitro maturation that could mitigate seasonal effects.

Effect of photoperiodicity and methods of follicular wave emergence on follicle turn-over, recovery and quality of oocytes, and early in-vitro developmental competence of embryos using ovum pick-up in Nili-Ravi buffaloes: Preliminary evidence

The objectives of the present study were to evaluate the effects of photoperiodicity, gauge (G) of ovum pick-up (OPU) needle, and two methods of follicular wave emergence on follicular turn-over, oocyte recovery (OR), quality of the oocytes (OQ), and early in-vitro developmental competence of embryos in Nili-Ravi buffaloes (n = 20). In 1^st experiment, buffaloes (n = 12; 4 buffaloes/season) were randomly assigned to optimize the OPU's (n) either with 17 G or 18 G needle in one of the following seasons: 1) peak breeding season (PBS; Sep-Nov; n = 31), 2) transition breeding season (TBS; Dec-Feb; n = 32), and 3) low breeding season (LBS; Apr-June; n = 32). During 2^nd experiment, buffaloes (n = 8) were enrolled randomly in a 2 × 2 cross-over design to compare the two methods of wave emergence either using follicular ablation (FA; n = 4), or synchronization protocol (CIDR-EB; n = 4) during PBS. In FA method, the ovarian follicles were aspirated (week -1), and subsequently repeated OPU's (n = 55) were performed for 7 weeks. However, in CIDR-EB synchronized buffaloes, a progesterone device (CIDR) was inserted in the anterior vagina and a single dose of estradiol benzoate (2 mg) and prostaglandin (150 μg) were administered i.m. on d 1. The CIDR was removed on d 7 and repeated OPU's (n = 56) were performed. In both experiments, a 7-d resting period was provided between each OPU session. Data on the follicular turn-over, OR, OQ, and early stages of embryonic development were analyzed with mixed models using the PROC MIXED and GLIMMIX procedures of SAS. Results revealed that the number of medium sized follicles (LSM ± SEM) and rate of OR (%) were greater (P < 0.05) during PBS (2.76 ± 0.40; 61%) and TBS (1.73 ± 0.30; 54%) as compared to LBS (0.68 ± 0.30; 31%) in buffaloes, respectively. The OR rate was also greater (P < 0.05) using 17 G as opposed to 18 G needle (62% vs. 35%), however, there was no effect (P > 0.05) of season and G of needle on OQ in buffaloes. In experiment 2, the number of small (3.50 ± 0.63 vs.2.69 ± 0.60) sized follicles was higher (P < 0.05) in FA, whereas, medium (1.13 ± 0.45 vs. 1.59 ± 0.45) sized follicles were greater (P < 0.05) in CIDR-EB synchronized buffaloes. The OR rate (67% vs. 53%), and OQ (Grade I_+_II; 15% vs. 16% and Grade III_+_IV; 85% vs. 84%), remained similar (P > 0.05) in FA and CIDR-EB treated buffaloes, respectively. Similarly, rates of in-vitro maturation (66% vs. 59%), cleavage (42% vs. 53%), 4-cell (27% vs. 32%), 8-cell staged embryos (23% vs. 25%), and morula (13% vs. 8%) did not differ (P > 0.05) between FA and CIDR-EB methods of follicular wave emergence, respectively. Taken together, it is concluded that peak or transition breeding seasons are suitable to perform OPU using 17 G needle for maximum follicular turn-over, and OR in buffaloes. However, the two fundamental methods of synchronization of wave emergence resulted in similar efficiency for OPU derived in-vitro embryo production in Nili-Ravi buffaloes.

RNA-seq profiling of skin in temperate and tropical cattle

Skin is a major thermoregulatory organ in the body controlling homeothermy, a critical function for climate adaptation. We compared genes expressed between tropical- and temperate-adapted cattle to better understand genes involved in climate adaptation and hence thermoregulation. We profiled the skin of representative tropical and temperate cattle using RNA-seq. A total of 214,754,759 reads were generated and assembled into 72,993,478 reads and were mapped to unique regions in the bovine genome. Gene coverage of unique regions of the reference genome showed that of 24,616 genes, only 13,130 genes (53.34%) displayed more than one count per million reads for at least two libraries and were considered suitable for downstream analyses. Our results revealed that of 255 genes expressed differentially, 98 genes were upregulated in tropically-adapted White Fulani (WF; Bos indicus) and 157 genes were down regulated in WF compared to Angus, AG (Bos taurus). Fifteen pathways were identified from the differential gene sets through gene ontology and pathway analyses. These include the significantly enriched melanin metabolic process, proteinaceous extracellular matrix, inflammatory response, defense response, calcium ion binding and response to wounding. Quantitative PCR was used to validate six representative genes which are associated with skin thermoregulation and epithelia dysfunction (mean correlation 0.92; p < 0.001). Our results contribute to identifying genes and understanding molecular mechanisms of skin thermoregulation that may influence strategic genomic selection in cattle to withstand climate adaptation, microbial invasion and mechanical damage.

Ameliorating postpartum reproductive cyclicity using exogenous melatonin implant in water buffalo (Bubalus bubalis)

This study was conducted to evaluate the impact of melatonin implants on oxidative stress levels and improving reproductive cyclicity in early postpartum buffalo. Total of 30 buffaloes at 15 days postpartum were randomly divided into melatonin treatment (n=15, one melatonin implant/50 kg body weight, 18 mg melatonin/implant) and control (n=15) groups. Both the groups were equally monitored for overt estrus signs and subjected to trans-rectal ultrasonography to check ovarian status. The blood samples were collected from jugular vein at weekly interval from day 15 to 43 post-partum to assess oxidative stress status. Significant reduction in concentration of malondialdehyde was observed in blood plasma from day 36 postpartum in treatment as compared to control buffaloes. The superoxide dismutase increased in treatment group from day 29 postpartum as compared to control. The concentration of glutathione reductase revealed nonsignificant difference between the groups. Treatment buffaloes showed higher oestrous exhibition rate (66.6% v/s 26.6%) with significant early onset of overt oestrus signs (24.10±1.49 days) compared to control (34.25±5.25 days). Ovulation rate was higher in treatment (n= 13; 86.66%) than that in control (n=8; 53.33%) buffaloes. In conclusion, melatonin implants efficiently reduced oxidative stress and resulted early resumption of ovarian activity, higher oestrus exhibition and ovulation rates in postpartum buffaloes.

Reproduction in female wild cattle: Influence of seasonality on ARTs

Wild cattle species, often considered less alluring than certain conservation-dependent species, have not attracted the same level of interest as the charismatic megafauna from the general public, private or corporate donors, and other funding agencies. Currently, most wild cattle populations are vulnerable or threatened with extinction. The implementation of reproductive technologies to maintain genetically healthy cattle populations in situ and ex situ has been considered for more than 30 years. Protocols developed for domestic cattle breeds have been used with some success in various wild cattle species. However, inherent differences in the natural life history of these species makes extrapolation of domestic cattle protocols difficult, and in some cases, minimally effective. Reproductive seasonality, driven by either photoperiod or nutritional resource availability, has significant influence on the success of assisted reproductive technologies (ARTs). This review focuses on the physiological processes that differ in breeding (ovulatory) and non-breeding (anovulatory) seasons in female cattle, and the potential methods used to overcome these challenges. Techniques to be discussed within the context of seasonality include: estrus synchronization and ovulation induction, ovarian superstimulation, artificial insemination (AI), multiple ovulation embryo transfer (MOET), and ovum pick-up (OPU) with in vitro fertilization (IVF) and embryo transfer (ET).

Exogenous and endogenous factors in seasonality of reproduction in buffalo: A review

Seasonal breeding in buffalo is influenced by exogenous (photoperiod, climate, nutrition, management) and endogenous (hormones, genotype) factors. Buffalo are negatively photoperiodic and show a natural increase in fertility during decreasing day length. The hormone melatonin is produced by the pineal gland and has a fundamental role in photoperiodic time measurement within the brain. This drives annual cycles of gonadotropin secretion and gonadal function in buffaloes. Some melatonin is released into the systemic circulation and, together with peripherally produced melatonin, acts at somatic tissues. In the ovaries and testes of buffalo, melatonin acts as an antioxidant and scavenges oxygen free radicals to reduce both oxidative stress and apoptosis. This has beneficial effects on gametogenesis and steroidogenesis. Female buffalo treated with melatonin show an improved response to estrus synchronization protocols in out-of-season breeding. Melatonin acts through melatonin receptors MT₁ and MT₂ and the gene for MT₁ (MTNR1A) is polymorphic in buffaloes. Single nucleotide polymorphisms (SNPs) in gene MTNR1A have been associated with fertility in female buffalo. The knowledge and tools are available to lift the reproductive performance of buffalo. This is highly important as the global demand for nutritious buffalo food products has undergone a sharp rise, and continues to grow. Buffalo can make an important contribution to affordable, nutritious animal protein. This will help address global nutritional security.

Synchronization and resynchronization strategies to improve fertility in dairy buffaloes

Dairy buffalo has an integral role in the sustenance of economics due to its substantial contribution in milk and meat industry, however, the reproduction in this species is challenging. During the last decade, our laboratory conducted a series of experiments to encapsulate the solutions of the problems through optimizing pre- and post-insemination interventions in dairy buffaloes. In an unique study, we proposed that timing of ovulation with reference to the onset of standing heat during spontaneous estrus is delayed, and subsequently re-framed the traditional AM-PM rule (AI after 12 h of standing heat) to AM-AM or PM-PM (AI after 24 h of standing heat) to achieve the optimum fertility using frozen thawed semen in dairy buffaloes. Pregnancy per AI (P/AI) varied substantially either via injecting single shot of prostaglandin (PG) F_2α to perform AI at detected estrus or applying standard ovsynch protocol for timed AI (TAI) in buffaloes. However, estrus response, and P/AI remained similar either with used or new controlled internal drug release device in dairy buffaloes. Additionally, the incorporation of estradiol benzoate in progesterone (P4) based protocol resulted in controlled emergence of follicular wave and increased the estrus intensity in buffaloes. Thereafter, we fine-tuned P4-based protocols to optimize the ovulation window for TAI either using GnRH or human chorionic gonadotropin (hCG) or equine chorionic gonadotropin that ultimately improved the fertility in dairy buffaloes. Although, these hormonal interventions resulted in decent fertility, yet it was consistently being compromised due to early or late embryonic losses in dairy buffaloes. Administration of hCG or GnRH on d 7 or 23 or 25 post AI has been proved beneficial to enhance the embryonic survival in buffaloes. Recently, resynchronization program as an aggressive reproductive management approach has been tested that served as a dual-purpose tool to increase overall herd fertility and reduce embryonic losses at commercial buffalo farm operations. Taken together, we concluded that the solutions to the problems of reproductive function are now clearly available with acceptable fertility, however, their application to the small holder buffalo farming remains challenging.

Prevalence, risk factors and constraints in control of repeat breeding in dairy animals of Punjab

The present study investigated the occurrence of repeat breeding (RB) and constraints in controlling this disease in cattle and buffalo in Punjab. Livestock owners/households (720) constituted the ultimate sampling units for the study. The dairy farmers were categorized into small (5–10 animals), medium (11–50) and large (>50) farmers. The overall prevalence of repeat breeding in the study area was 27.6%. It varied significantly with respect to herd size and categories of animals except in buffaloes. The highest prevalence was observed in crossbred cattle (41.8%), followed by indigenous cattle (32.0%) and buffaloes (17.6%). Repeat breeder animals were mostly high yielders (with >15 kg milk yield), calved mostly in winter season, having below average body condition score (BCS). No significant correlation was observed between parity (lactation number) and type of calving and prevalence of repeat breeding. The major constraint (rank I) perceived by farmers was culling of affected problematic cows, and lack of effective and accurate estrus detection in buffaloes. The other major constraints perceived in the study area were high cost of veterinary medicine, poor conception rate following artificial insemination and inaccessibility of qualified veterinarian. The lack of knowledge regarding animal nutrition and higher cost of branded feed available in the market were responsible for low body condition score of affected animals. Thus, a comprehensive policy and programmes involving various stakeholders are required for effective control of repeat breeding in Punjab.

Expression of Kisspeptin and its receptor in the hypothalamus of cyclic and acyclic buffalo (Bubalus bubalis)

Kisspeptin (Kiss1), neurokinin-B (NKB) and dynorphin (Dyn) neurons regulate the surge and pulsatile centres of gonadotropin releasing hormone (GnRH) in the hypothalamus and are modulated by the ovarian steroids. Accordingly, we studied the temporospatial expression of Kiss1, its receptor and other genes that regulate GnRH in the preoptic area (POA) and arcuate (ARC) regions of hypothalamus at different phases of bubaline estrous cycle. Brain of buffalo (n = 32) was collected immediately after exsanguination and categorized into early luteal (EL), mid luteal (ML), follicular (FL) stages and acyclic (n = 8/group). Total RNA was extracted from the POA and ARC of each stage and real time PCR amplification of Kiss1, Kiss1r, NKB, NKB receptor (NKBR), Dyn, Dyn receptor (OPRK1), GnRH1, ERα, PR, LEPR and GHSR was done using GAPDH as endogenous control and acyclic stage as calibrator group. Further, immunolocalization of Kiss1 and Kiss1r was done on the hypothalamus. In the POA, significant up-regulation of Kiss1 and NKB with a concomitant down-regulation of Dyn transcripts was recorded at FL stage. There was, however, down-regulation of Kiss1 and Kiss1r during the EL perhaps due to the loss of estradiol as a consequence of ovulation. On the other hand, in the ARC, there was a significant up-regulation of Kiss1 and Dyn at FL and ML, while NKB transcript was consistently down-regulated at any stage of estrous cycle. In the POA, expression of ERα was not modulated; however, PR was down-regulated in the EL. In the ARC, the ERα expression was significantly up-regulated in the EL, whereas, PR was moderately expressed irrespective of the stage of estrous cycle. The immunolocalization study revealed the presence of Kiss1 and Kiss1r in the POA and ARC in the cyclic buffalo with relative abundance at FL. The transcriptional profile of the genes suggests that there is estrous cycle stage specific expression of Kiss1, Kiss1r and other GnRH regulating genes in the POA and ARC regions of hypothalamus in the buffalo. Up-regulation of Kiss1r in the POA during ML and ARC during EL indicates the involvement of kisspeptinergic system in the regulation of low LH pulse frequencies during the early and mid luteal phases in the cyclic buffalo.

Evaluation of anti-mullerian hormone in heifers and anestrus Murrah buffaloes

An experiment was conducted to quantify the anti-mullerian hormone (AMH) concentration in heifers and anestrus Murrah buffaloes during fortnight blood collections for 3 months. Two groups of heifer and anestrus Murrah buffaloes were formed on the basis of record and actual per rectal examination. Serum AMH concentration was determined by ELISA method, using bovine AMH ELISA kit. Nonsignificant difference was recorded in AMH concentration (pg/ml) in heifer and anestrus buffaloes during fortnight collection (0, 15, 30, 45, 60 and 75). Highly significant individual variation was observed in heifer and anestrus buffaloes in this study. Heifers (6) with AMH concentration above 200 pg/ml were pregnant and 4 heifers with AMH concentration below 200 pg/ml were non pregnant. AMH concentration is a reliable phenotypic marker to predict the number of healthy follicles and oocytes, in ovaries and predict the future potential of heifers and young adult buffaloes. The cut-off value of AMH concentration in Murrah heifers buffaloes as a marker of fertility may be 200 pg/ml. However, study with more number of buffaloes is required to determine the accurate cut-off value of AMH concentration.

Effect of season on dairy buffalo reproductive performance when using P4/E2/eCG-based fixed-time artificial insemination management

This study aimed to compare the reproductive efficiency of dairy buffaloes subjected to TAI protocols based on progesterone, estrogen, and equine chorionic gonadotrophin (P4/E2+eCG) during the fall/winter (n = 168) and spring/summer (n = 183). Buffaloes received an intravaginal P4 device (1.0 g) plus estradiol benzoate (EB; 2.0 mg im) at a random stage of the estrous cycle (D-12). Nine days later (D-3), the P4 device was removed and buffaloes were given PGF_2α (0.53 mg im sodium cloprostenol) plus eCG (400 IU im). GnRH (10 μg im buserelin acetate) was administered 48 h after P4 device removal (D-1). All animals were subjected to TAI 16 h after GnRH administration (D0). Frozen-thawed semen from one bull was used for all TAI, which were all performed by the same technician. Ultrasound examinations were performed on D-12 and D-3 to ascertain cyclicity (presence of CL), D-3 and D0 to measure the diameter of the dominant follicle (ØDF), D+10 to verify the ovulation rate and diameter of the corpus luteum (ØCL), and D+30 and D+45 to detect pregnancy rate (P/AI 30d and 45d, respectively) and embryonic mortality (EM). Fetal mortality (FM) was established between 45 days and birth, and pregnancy loss between 30 days and birth. There were significant differences between fall/winter and spring/summer only for cyclicity rate [76.2% (128/168) vs. 42.6% (78/183); P = 0.02]. The others variables did not differ between the seasons: ØDF on D-3 (9.6 ± 0.2 mm vs. 9.8 ± 0.2 mm; P = 0.35); ØDF on D0 (13.1 ± 0.2 mm vs. 13.2 ± 0.2 mm; P = 0.47); ovulation rate [86.9% (146/168) vs. 82.9% (152/182); P = 0.19]; ØCL on D+10 (19.0 ± 0.3 mm vs. 18.4 ± 0.3 mm, P = 0.20); P/AI on D+30 [66.7% (112/168) vs. 62.7% (111/177); P = 0.31]; P/AI on D+45 [64.8%% (107/165) vs. 60.2% (106/176); P = 0.37]; EM [1.8% (2/111) vs. 3.6% (4/110); P = 0.95]; FM [21.9% (18/82) vs. 8.0% (7/87); P = 0.13]; and PL [23.8% (20/84) vs. 12.1% (11/91); P = 0.13]. In conclusion, dairy buffaloes present similar reproductive efficiency in fall/winter and spring/summer when subjected to P4/E2/eCG-based protocol for TAI.

Efficacy of different methods for detecting the onset of ovarian cyclicity in post-partum Murrah buffaloes

This study was designed to investigate the sensitivity and specificity of three methods for detecting the onset of cyclicity in post-partum Murrah buffaloes. The methods investigated were visual signs, transrectal ultrasonography, and serum progesterone (P₄) assay. For this study, 102 post-partum Murrah buffalo cows were grouped for monitoring their ovarian activity. The first group of buffaloes was between 26 and 35 days post-partum. Thereafter, the buffalo cows that calved were grouped after every 10 days for the study sample. Thus, the study animals were adjudged between 26 and 35, 36-45, 46-55, 56-65, 66-75, 76-85, and 86-95 days post-partum with an average of 30, 40, 50, 60, 70, 80, and 90 days post-partum, respectively. Visual estrus signs were monitored twice daily, and simultaneously, ultrasound examination was carried out at 10 days interval for accessing the presence of corpus luteum (CL). Serum P₄ was estimated in the animals which were adjudged cyclic by ultrasound examination, and the assay was repeated after 10 days. The buffalo cows in estrus were inseminated artificially, and pregnancy status was assessed after 30 days post-insemination. In this study, the sensitivity and specificity of visual observation were low (39.37 and 70.73%, respectively) when compared to P₄ assay (98.80 and 96.47%) and ultrasound examination (single, 97.59 and 97.59%; double, 100 and 100%), respectively. Furthermore, the sensitivity and specificity of single and double ultrasound examination and P₄ assay were comparable. In conclusion, this study reports that single and double ultrasound examination and P₄ assay are more efficient than visual observation in detecting the onset of ovarian cyclicity in post-partum Murrah buffaloes.

Effect of breeding method and season on pregnancy rate and embryonic and fetal losses in lactating Nili-Ravi buffaloes

The aim of this study was to determine the effect of breeding method and season on pregnancy rate and cumulative embryonic and fetal losses in Nili-Ravi buffalo. Estrus detection was performed twice a day by teaser buffalo bull for 1 hour each. A 2 × 2 factorial design was used to address the breeding method and season. Buffaloes (n = 130) exhibiting estrus were randomly assigned to be bred either in peak breeding season (PBS; n = 80) or low breeding season (LBS; n = 50). Within each season, buffaloes were divided to receive either natural service (NS; n = 65) or artificial insemination (AI; n = 65). NS buffaloes, in estrus, were allowed to remain with the bull until mating. AI was achieved, using frozen thawed semen of bull of known fertility. PBS comprised of September to December and LBS were from May to July. Serial ultrasonography was performed on days 30, 45, 60, and 90 after breeding (day 0) to monitor pregnancy rate and embryonic and fetal losses. The pregnancy rate on day 30 after breeding was higher in NS as compared to AI group (63 vs. 43%; P < 0.05) during PBS while it did not differ (48 vs. 32%; P > 0.05) in LBS. The cumulative embryonic and fetal losses between days 31 and 90 were significantly lower in PBS than LBS (33 vs. 60%; P < 0.05), ignoring breeding method. Pregnancy rates were better with NS in PBS, and cumulative embryonic fetal losses were higher in LBS in Nili-Ravi buffalo.

Effect of heat stress on reproductive performances of dairy cattle and buffaloes: A review

Heat stress has adverse effects on the reproductive performances of dairy cattle and buffaloes. The dairy sector is a more vulnerable to global warming and climate change. The temperature humidity index (THI) is the widely used index to measure the magnitude of heat stress in animals. The objective of this paper was to assess the decline in performances of reproductive traits such as service period, conception rate and pregnancy rate of dairy cattle and buffaloes with respect to increase in THI. The review stated that service period in cattle is affected by season of calving for which cows calved in summer had the longest service period. The conception rate and pregnancy rate in dairy cattle were found decreased above THI 72 while a significant decline in reproductive performances of buffaloes was observed above threshold THI 75. The non-heat stress zone (HSZ) (October to March) is favorable for optimum reproductive performance, while fertility is depressed in HSZ (April to September) and critical HSZ (CHSZ) (May and June). Heat stress in animals has been associated with reduced fertility through its deleterious impact on oocyte maturation and early embryo development. The management strategies viz., nutrition modification, environment modification and timed artificial insemination protocol are to be strictly operated to ameliorate the adverse effects of heat stress in cattle and buffaloes during CHSZ to improve their fertility. The identification of genes associated with heat tolerance, its incorporation into breeding program and the inclusion of THI covariate effects in selection index should be targeted for genetic evaluation of dairy animals in the hot climate.

Investigating temporary acyclicity in a captive group of Asian elephants (Elephas maximus): Relationship between management, adrenal activity and social factors

Routine faecal steroid monitoring has been used to aid the management of five captive Asian elephant (Elephas maximus) females at Chester Zoo, UK, since 2007. Progestagen analysis initially revealed synchronised oestrous cycles among all females. However, a 14- to 20-week period of temporary acyclicity subsequently occurred in three females, following several management changes (increased training, foot-care and intermittent matriarch removal for health reasons) and the initiation of pregnancy in another female. The aim of this study was to retrospectively investigate whether these management changes were related to increased adrenal activity and disruption of ovarian activity, or whether social factors may have been involved in the temporary cessation of cyclicity. Faecal samples collected every other day were analysed to investigate whether glucocorticoid metabolites were related to reproductive status (pregnant, cycling, acyclic) or management (training, foot-care, matriarch presence). Routine training and foot-care were not associated with adrenal activity; however, intensive foot-care to treat an abscess in one female was associated with increased glucocorticoid concentration. Matriarch presence influenced adrenal activity in three females, being lower when the matriarch was separated from the group at night compared to being always present. However, in the females that exhibited temporary acyclicity, there was no consistent relationship between glucocorticoids and cyclicity state. Although the results of this study do not fully explain this occurrence, the highly synchronised nature of oestrous cycles within this group, and the concurrent acyclicity in three females, raises the question of whether social factors could have been involved in the temporary disruption of ovarian activity.

Supplementation of Slow-Release Melatonin Improves Recovery of Ovarian Cyclicity and Conception in Summer Anoestrous Buffaloes (Bubalus bubalis)

The role of melatonin as a protective neurohormone against restoring cyclicity in summer anoestrous animals in photoperiod species has gained wider acceptance. This study was designed to uncover the evidence the slow-release melatonin (MLT) has on initiation of ovarian cyclicity and conception rate (CR) in summer anoestrous buffaloes. Thus, buffaloes diagnosed as summer anoestrous (absence of overt signs of oestrus, concurrent rectal examination and radioimmunoassay for serum progesterone at 10 days interval) were grouped as untreated (Group I, sterilized corn oil, n = 8) and treated (Group II, single subcutaneous injection of MLT @18 mg/50 kg bwt in sterilized corn oil, n = 20). Animals treated and detected in oestrus were artificially inseminated (AI) followed by division into Group III (second dose of MLT on 5th day post-AI, n = 8) and Group IV (no melatonin administration, n = 10). Blood samples were collected at 4 days interval for estimation of serum MLT, progesterone and oestrogen using radioimmunoassay kit. Mean oestrous induction rate (OIR), oestrous induction interval (OII), interoestrous interval (IOI) and CR were estimated. Compared to control, concentration of melatonin was significantly (p < 0.05) higher in treated group ranging from 14.34 ± 1.72 to 412.31 ± 14.47 pg/ml whereas other two hormones did not show any concentration difference. Melatonin-administered buffaloes showed significantly (p < 0.05) higher (90%) OIR with OII of 18.06 ± 1.57 days. Results showed improvement in conception rate in buffaloes administered with post-insemination melatonin. It can be concluded from the study that slow-release melatonin supplementation restored cyclicity in summer anoestrous animals resulting in improvement in conception rate in buffaloes.

LH peak and ovulation after two different estrus synchronization treatments in buffalo cows in the daylight-lengthening period

The aim of this study was to determine the timing of ovulation in relation to the LH peak after synchronization using PRID or Ovsynch protocols, to assess the effects of the period of treatment on these parameters and to provide information concerning how to use the two main protocols for fixed-time artificial insemination in buffalo. Forty-eight lactating Italian Mediterranean buffalo cows were used. The buffaloes were treated in various periods as follows: February to March (n = 12 PRID, n = 12 Ovsynch), end of the breeding season, May to June (n = 12 PRID, n = 12 Ovsynch), beginning of low-breeding season according to Italian environmental conditions. To determine the LH, blood samples were taken at 4-hour intervals, starting 24 hours from PRID removal (PRID group) or 12 hours from (PGF2α) injection (Ovsynch group) up to 108 hours. The ovaries were monitored by transrectal ultrasonography to verify ovulation. The LH-ovulation interval was similar in both groups (30.10 ± 1.05 and 32.77 ± 1.15 hours, respectively, in PRID and Ovsynch group). In the PRID group, the timing of ovulation in relation to device removal was 76.83 ± 3.65 hours with a high level of variability among the animals. In the Ovsynch group, we observed a better synchronization of LH peaks and ovulations, and the timing of ovulation in relation to the last GnRH injection was 35.67 ± 1.15 hours. The percentage of animals reaching the LH peak and ovulation was lower (P ≤ 0.05) in May to June (respectively 75.0% and 54.1%) compared to February to March (respectively 95.8% and 83.3%), indicating a reduction of hypothalamus-pituitary responsiveness to the synchronization treatments in the daylight-lengthening period.

Seasonal variations of the ovarian activity and pregnancy rate in the Egyptian buffalo cows (Bubalus bubalis)

The objective of this study was to investigate the effect of season on the follicular and luteal dynamics and pregnancy rate in Egyptian buffaloes. A total of 327 genital tracts and 596 animals were used. The genital tracts were examined in winter (n = 58), spring (n = 179), summer (n = 49), and autumn (n = 41) for follicular population, incidence of presence of developed or mature corpus luteum (CL), and diameters of the preovulatory follicle (OF) and the mature CL. Buffaloes were mated in winter (n = 297) and summer (n = 299) and examined for pregnancy rate. Results showed that the mean number of the large follicles was higher in winter (1.21 ± 0.08 mm) and spring (1.04 ± 0.05 mm) than in summer (0.64 ± 0.1 mm) and autumn (0.78 ± 0.1 mm) (P = 0.0001). Likewise, the mean diameter of the OF was greater in winter (14.71 ± 0.7 mm) and spring (14.36 ± 0.5 mm) than in summer (12.4 ± 0.8 mm) and autumn (12 ± 0.8 mm) (P = 0.02). In addition, the mean diameter of the mature CL was higher in winter (15.8 ± 0.4 mm) and spring (15.5 ± 1.1 mm) than in summer (14.2 ± 1 mm) and autumn (13.2 ± 0.7 mm) (P = 0.003). The incidence of presence of developed or mature CL was lower in summer (69.4 %) than in winter (74.1 %), spring (87.2 %), or autumn (85.4 %) (P = 0.01). Double CLs (0.9 %) were observed only in spring. Ovarian cysts (2.5 %) were detected in winter and spring. The pregnancy rate was higher in buffaloes mated in winter (75.4 %) than in those mated in summer (61.9 %) (P = 0.0004). In conclusion, season affects the ovarian activity and reproductive efficiency of buffaloes, where winter and spring are the optimum seasons for breeding.

Assessment of expected breeding values for fertility traits of Murrah buffaloes under subtropical climate

Aim:

The aim of the present study was to assess the influence of temperature and humidity prevalent under subtropical climate on the breeding values for fertility traits viz. service period (SP), pregnancy rate (PR) and conception rate (CR) of Murrah buffaloes in National Dairy Research Institute (NDRI) herd.

Materials and Methods:

Fertility data on 1379 records of 581 Murrah buffaloes spread over four lactations and climatic parameters viz. dry bulb temperature and relative humidity (RH) spanned over 20 years (1993-2012) were collected from NDRI and Central Soil and Salinity Research Institute, Karnal, India. Monthly average temperature humidity index (THI) values were estimated. Threshold THI value affecting fertility traits was identified by fixed least-squares model analysis. Three zones of non-heat stress, heat stress and critical heat stress zones were developed in a year. The genetic parameters heritability (h²) and repeatability (r) of each fertility trait were estimated. Genetic evaluation of Murrah buffaloes was performed in each zone with respect to their expected breeding values (EBV) for fertility traits.

Results:

Effect of THI was found significant (p<0.001) on all fertility traits with threshold THI value identified as 75. Based on THI values, a year was classified into three zones: Non heat stress zone(THI 56.71-73.21), HSZ (THI 75.39-81.60) and critical HSZ (THI 80.27-81.60). The EBVfor SP, PR, CR were estimated as 138.57 days, 0.362 and 69.02% in non-HSZ while in HSZ EBV were found as 139.62 days, 0.358 and 68.81%, respectively. EBV for SP was increased to 140.92 days and for PR and CR, it was declined to 0.357 and 68.71% in critical HSZ.

Conclusion:

The negative effect of THI was observed on EBV of fertility traits under the non-HSZ and critical HSZ Thus, the influence of THI should be adjusted before estimating the breeding values for fertility traits in Murrah buffaloes.

Reference gene selection for gene expression analysis of oocytes collected from dairy cattle and buffaloes during winter and summer

Oocytes from dairy cattle and buffaloes have severely compromised developmental competence during summer. While analysis of gene expression is a powerful technique for understanding the factors affecting developmental hindrance in oocytes, analysis by real-time reverse transcription PCR (RT-PCR) relies on the correct normalization by reference genes showing stable expression. Furthermore, several studies have found that genes commonly used as reference standards do not behave as expected depending on cell type and experimental design. Hence, it is recommended to evaluate expression stability of candidate reference genes for a specific experimental condition before employing them as internal controls. In acknowledgment of the importance of seasonal effects on oocyte gene expression, the aim of this study was to evaluate the stability of expression levels of ten well-known reference genes (ACTB, GAPDH, GUSB, HIST1H2AG, HPRT1, PPIA, RPL15, SDHA, TBP and YWHAZ) using oocytes collected from different categories of dairy cattle and buffaloes during winter and summer. A normalization factor was provided for cattle (RPL15, PPIA and GUSB) and buffaloes (YWHAZ, GUSB and GAPDH) based on the expression of the three most stable reference genes in each species. Normalization of non-reference target genes by these reference genes was shown to be considerably different from normalization by less stable reference genes, further highlighting the need for careful selection of internal controls. Therefore, due to the high variability of reference genes among experimental groups, we conclude that data normalized by internal controls can be misleading and should be compared to not normalized data or to data normalized by an external control in order to better interpret the biological relevance of gene expression analysis.

Effects of treatment for anestrus in water buffaloes with PGF2α and GnRH in comparison with vitamin-mineral supplement, and some factors influencing treatment effects

The effect of treatment for anestrus in buffaloes with a PGF2α or GnRH injection and vitamin-mineral (Vit-M) supplementation for 1 to 2 months and some factors influencing the treatment effect were studied. In anestrus buffaloes with CL, an injection of PGF2α tended to show higher estrus detection and pregnancy rates within 17 days after treatment than Vit-M supplementation (P<0.10). In those with inactive ovaries, effect of GnRH and Vit-M did not differ. Body condition score of the animals before treatment affected pregnancy rate within 17 days after treatment (P<0.05). Pregnancy rate within 4 months after treatment was adversely influenced by low serum concentrations of calcium (P<0.01) and gastrointestinal parasitic infection before treatment (P<0.05).

In vivo and in vitro environmental effects on mammalian oocyte quality

The oocyte is at the center of the equation that results in female fertility. Many factors influence oocyte quality, including external factors such as maternal nutrition, stress, and environmental exposures, as well as ovarian factors such as steroids, intercellular communication, antral follicle count, and follicular fluid composition. These influences are interconnected; changes in the external environment of the female translate into ovarian changes that affect the oocyte. The lengthy period during which the oocyte remains arrested in the ovary provides ample time and opportunity for environmental factors to take their toll. An appropriate environment for growth and maturation of the oocyte, in vivo and in vitro, is critical to ensure optimal oocyte quality, which determines the success of fertilization and preimplantation embryo development, and has long-term implications for implantation, fetal growth, and offspring health.