Assessment of conception rate in postpartum cyclic buffaloes under field conditions

Introduction

The reproductive efficiency continues to be one of the major constraints limiting profitable buffalo production under field conditions. Delayed resumption of ovarian cyclicity, postpartum anestrous, silent estrus, uterine infections and poor conception rates frequently prolong calving interval and adversely affect the reproductive efficiency Therefore, improvement of conception rate during the postpartum period is essential for enhancement of reproductive efficiency and economic sustainability of buffalo farming. Efficient reproductive performance in buffaloes depends upon proper endocrine regulation, ovarian cyclicity and managemental interventions during the postpartum period (Madan and Prakash, 2007) [10] . Proper uterine involution and restoration of reproductive cyclicity are essential prerequisites for successful conception during the postpartum period in bovines (Roberts, 1971; Noakes et al., 2018) [16,13] . Subclinical uterine infections are recognized as one of the important hidden causes of infertility in bovines. Unlike clinical endometritis, subclinical uterine inflammation frequently remains unnoticed because of absence of obvious clinical signs but significantly compromises uterine environment and conception potential (Kasimanickam et al., 2004) [8] . Therefore, identification and exclusion of buffaloes affected with uterine inflammation prior to insemination may substantially improve fertility outcome. Apart from uterine health, postpartum nutritional and managemental interventions considerably influence reproductive performance in buffaloes. Parasitic burden and nutritional insufficiency frequently compromise reproductive efficiency through poor metabolic status, delayed ovarian activity and weak estrus expression (Campanile et al., 2010) [3] . Likewise, estrus intensity serves as an important determinant of successful conception, since buffaloes exhibiting intense estrus generally show better follicular maturity and ovulatory response than animals exhibiting weak estrus signs (Roelofs et al., 2005) [17] .

Despite several advances in buffalo reproductive management, limited information is available regarding conception-oriented fertility management in postpartum cyclic graded Murrah buffaloes maintained under field conditions. Hence, the present investigation was undertaken to assess conception rate in postpartum cyclic buffaloes following systematic uterine health screening, postpartum management and artificial insemination under field conditions.

Materials and Methods

Study area and experimental animals

The present investigation was conducted under field conditions in cyclic graded Murrah buffaloes presented to the Department of Veterinary Gynaecology and Obstetrics, NTR College of Veterinary Science, Gannavaram, and in nearby villages around Vuyyuru, Krishna district of Andhra Pradesh, during the period from August 2025 to March 2026 in different parities 60-120 days postpartum buffaloes. Detailed gynaecological examination was carried out through perrectal palpation to assess reproductive status, ovarian cyclicity and presence of abnormalities of the genital tract.

Screening for uterine health

Uterine health status was assessed using leucocyte esterase strip test (LEST) using reagent test strips (Shenhua, URS-11G) and uterine discharge cytology. Uterine discharge samples were collected aseptically by blue sheath (IMV, France) and subjected to cytological examination for determination of PMN infiltration. Buffaloes exhibiting more than 5 per cent PMN cells were considered positive for subclinical endometritis based on established cytological criteria for postpartum bovines (Kasimanickam et al., 2004) [8] and were excluded from breeding management.

Postpartum nutritional management

Buffaloes free from uterine infection were subjected to routine postpartum nutritional management practices under field conditions. Deworming was carried out using Albendazole administered orally at the dose rate of 10 mg/kg body weight as a single dose. Nutritional supplementation was provided through concentrate feeding (2-3 kg/animal/day) and mineral mixture supplementation (50 g/animal/day) from screening to insemination at subsequent estrus.

Estrus detection and artificial insemination

Estrus detection was carried out based on behavioural manifestations and physical signs including vulval edema, vaginal mucus discharge, mounting behaviour, restlessness and uterine tone. Estrus intensity was categorized as intense, intermediate and weak according to severity of estrus signs based on a standardized score card described by Rao and Rao (1981) [15] with slight modifications. Buffaloes exhibiting intense estrus signs at subsequent estrus were bred by artificial insemination during mid to late heat using frozen semen under standard field breeding practices.

Pregnancy diagnosis and statistical analysis

Pregnancy diagnosis was performed at Day 60 postinsemination through per-rectal examination. Based on pregnancy status, buffaloes were classified into pregnant and non-pregnant groups. Data obtained was analysed using Statistical Package for Social Sciences (SPSS) software and expressed using descriptive statistics such as frequencies and percentages.

Ethical approval

The study was conducted in accordance with institutional guidelines for animal handling and welfare during clinical and reproductive examination of buffaloes. All procedures adopted during the present investigation were performed under standard veterinary management practices.

Results and Discussion

Screening of postpartum cyclic buffaloes for uterine health A total of 52 postpartum cyclic graded Murrah buffaloes were screened through detailed gynaecological examination, leucocyte esterase strip test (LEST) and uterine discharge cytology. The leucocyte esterase strip test revealed that 43 out of 52 buffaloes (82.69%) were negative for leucocyte esterase activity, whereas nine buffaloes (17.31%) showed varying degrees of positive reaction suggestive of uterine inflammation. Further, upon uterine discharge cytology, 46 buffaloes (88.46%) were found free from uterine infection and considered suitable for breeding, whereas six buffaloes (11.54%) were diagnosed positive for subclinical endometritis and excluded from the study. Positive agreement was observed between LEST and uterine discharge cytology, reaffirmed that LEST could be used as a rapid, economical, cow side and field-applicable diagnostic tool for identification of buffaloes suitable for immediate breeding. Early diagnosis and exclusion of animals affected with uterine inflammation likely minimized reproductive failure and contributed to better conception outcome in the present investigation. Similar observations were reported by Dhali et al. (2017) [4] , who observed good diagnostic reliability of leucocyte esterase strip test for detection of subclinical endometritis in bovines under field conditions. Nazhat et al. (2018) [11] also reported satisfactory agreement between LEST and uterine cytology for diagnosis of uterine inflammatory conditions. The exclusion of buffaloes affected with uterine inflammation prior to insemination was considered important for improving the fertility. Further, Sheldon et al. (2009) [18] reported that postpartum uterine diseases adversely influenced ovarian cyclicity and fertility through inflammatory and endocrine alterations. Likewise, Kasimanickam et al. (2004) [8] observed significantly reduced conception rates in postpartum dairy animals affected with subclinical endometritis owing to compromised uterine environment. The occurrence of subclinical endometritis recorded in the present study (11.54%) was comparatively lower than several reports in bovines under field conditions. Gahlot et al. (2017) [6] documented higher prevalence of uterine inflammation in postpartum buffaloes, whereas Gilbert et al. (2005) [7] reported that uterine inflammatory conditions during the postpartum period substantially reduced fertility performance. Lower prevalence observed in the present study might be attributed to screening of cyclical buffaloes conducted during 60-120 days postpartum. The PMN threshold of >5%, employed in the present investigation served as an important criterion for exclusion of buffaloes positive for subclinical endometritis before breeding. The findings of the present study were in close agreement with the observations of Kasimanickam et al. (2004) [8] , who reported that PMN percentages exceeding 5 per cent were indicative of subclinical endometritis that adversely affected fertility. Therefore, identification and exclusion of buffaloes exhibiting elevated PMN percentage prior to insemination might have contributed to improvement of reproductive efficiency under field conditions.

Postpartum nutritional management and estrus response

Comparable improvement in reproductive performance following appropriate postpartum management and nutritional interventions had been reported in buffaloes under field conditions (Campanile et al., 2010; Perera, 2011) [3,14] . The reproductively sound postpartum buffaloes were subjected to routine postpartum fertility management involving deworming and supplementation of concentrate and mineral mixture prior to breeding. Correction of parasitic burden through deworming might have contributed to improvement in physiological status and reproductive readiness of buffaloes. Improved reproductive performance following deworming has been reported in bovines under field conditions due to better metabolic adaptation and reproductive competence (Campanile et al., 2010) [3] . Similarly, nutritional supplementation through supplementation of concentrate feeding and mineral mixture might have positively influenced reproductive performance as observed in the present investigation. Postpartum buffaloes often experience increased nutritional demands associated with lactation and uterine recovery, which delay estrus and conception. Adequate nutritional supplementation had improved the ovarian activity, follicular growth and reproductive efficiency in buffaloes (Lucy, 2001; Zicarelli, 2020) [9,21] . Among the 46 buffaloes evaluated for estrus intensity at subsequent estrus, intense estrus was observed in 33 buffaloes (71.74%), whereas intermediate and weak estrus were recorded in 5 (10.87%) and 8 (17.39%) buffaloes, respectively (Table 1). The higher proportion of buffaloes exhibiting intense estrus was suggestive of favourable reproductive and endocrine status following postpartum nutritional management. Animals exhibiting intense estrus are generally characterized by improved follicular maturity, higher estrogenic activity and better synchronization between ovulation and insemination, thereby increasing probability of successful conception. Comparable observations were reported by Roelofs et al. (2005) [17] , who documented superior reproductive performance and higher conception rates in animals exhibiting pronounced estrus signs. Likewise, Perera (2011) [14] observed that buffaloes showing intense estrus expression exhibited improved ovulatory response and superior conception outcome compared to weak estrus animals.

Conception rate in postpartum cyclic buffaloes

Thirty-three buffaloes exhibiting intense estrus signs bred by artificial insemination during the mid to late heat as appropriate timing of insemination relative to onset of estrus remained an important determinant of conception success in bovines (Nebel et al., 2000) [12] . Pregnancy diagnosis was carried out through per-rectal examination at Day 60 postinsemination and the conception rate recorded was 42.42 per cent, with 14 buffaloes (42.42%) being pregnant while 19 buffaloes (57.58%) were non-pregnant. The conception rate recorded in the present investigation was considered satisfactory under field conditions, particularly during the postpartum period where reproductive inefficiency frequently remained a challenge in buffaloes. Conception in buffaloes was influenced by multiple interacting factors including uterine health, estrus intensity, nutritional status, insemination timing and environmental conditions. Efficient estrus detection and appropriate timing of insemination had been recognized as important determinant for the success of conception in dairy animals (Stevenson, 2001) [19] . The moderate conception rate observed in the present study might be attributed to systematic reproductive screening and postpartum nutritional management adopted before insemination. Baruselli et al., (2001) [1] emphasized that proper estrus detection and timely insemination substantially enhanced fertility performance in cyclic buffaloes. Similarly, Campanile et al., (2007) [2] further reported that reproductive efficiency and conception outcome in buffaloes were influenced by physiological and managemental factors, particularly during periods of reproductive stress and postpartum recovery. Comparable results for buffaloes under field conditions had been reported by Warriach et al., (2015) [20] , who observed conception rates ranging between 35-50 per cent depending upon nutritional management, estrus detection efficiency and reproductive status. Adequate nutritional support during the postpartum period had shown to improve ovarian cyclicity, follicular development and uterine recovery, thereby increasing fertility probability as also opined by Lucy (2001) [9] reported that reproductive success in dairy animals was strongly influenced by metabolic and nutritional status. Likewise, Campanile et al. (2010) [3] emphasized the role of nutrition in restoration of ovarian function and fertility in buffaloes. Despite stringent measures only 42.42 per cent buffaloes conceived, while a considerable proportion of animals remained non-pregnant (57.58%). Failure of conception in buffaloes could have resulted from unobserved estrus, inadequate follicular maturity, fertilization failure, embryonic mortality and environmental stress. Further, buffaloes were inherently characterized by poor estrus expression and delayed ovulatory response compared to cattle, thereby contributing to comparatively lower conception rates under field conditions (El-Wishy, 2007) [5] . The findings of the present study therefore indicated that conception in postpartum cyclic buffaloes could be improved through an integrated reproductive management approach involving screening for uterine health by LEST and uterine discharge cytology, postpartum nutritional management, proper estrus detection and insemination at mid to late heat.

Conclusion

The present investigation demonstrated that conception rate in postpartum cyclic graded Murrah buffaloes could be improved through systematic reproductive screening, postpartum nutritional management and timely artificial insemination under field conditions. Screening of buffaloes using leucocyte esterase strip test and uterine discharge cytology facilitated identification and exclusion of animals affected with subclinical endometritis, thereby improved the selection of reproductively healthy buffaloes for breeding.

Acknowledgement

AcknowledgementThe authors are thankful to the authorities of NTR College of Veterinary Science, Gannavaram, Sri Venkateswara Veterinary University, Andhra Pradesh, India, for providing

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