IAR Journal of Agriculture Research and Life Sciences ISSN Print : 2708-5090 | ISSN Online : 2708-5104 Frequency : Monthly Language : English Origin : Kenya Website : https://www.iarconsortium.org/journal-info/iarjals Research Arti cle Factors Affecting the First Service Pregnancy Rate in Cows at the Selected Coastal Region of Bangladesh Article History Received: Revision: Accepted: Published: 10.12. 2020 22. 12. 2020 09. 01 .2021 20. 01. 2021 Author Details Md. Shiful Islam1, Ashit Kumar Paul1*, Md. Selim Ahmed1, Himangsu Sarker2 and Dipa Rani Pal1 1 Authors Affiliations Department of Medicine, Surgery and Obstetrics, Faculty of Animal Science and Veterinary Medicine, Patuakhali Science and Technology University, Outer Campus, Babugonj, Barishal-8210, Bangladesh. 2 Department of Clinical Courses, Faculty of Veterinary and Animal Sciences, Gono Bishwabidyalay, Savar, Dhaka, Bangladesh. Corresponding Author* Ashit Kumar Paul How to Cite the Article: Abstract: The aim of this study is to evaluate the first service pregnancy rate in cows at the selected coastal areas of Bangladesh. The study was conducted during the period from September 2015 to September 2016 in 10 Upazilas in Barisal district of Bangladesh. Data were recorded by checking their record book, collecting information from Upazila Livestock Office and asking the farmer. A total of 1431 cows were selected considering potential factors Of, breed, age, parity, body weight, time of artificial insemination (AI) and feeding system. A descriptive analysis expressed as binary logistic regressions were done to measure the association and strength of association of different factors. The overall first AI pregnancy rate (PR/FAI) was 29.1%. The PR/FAI of Local, Cross and Sahiwal breed were 28.3, 30.9 and 20.0%, respectively, In the experiment the PR/FAI of cows aged on 2.0 to 4.0, 4.1 to 8.0, 8.1 to 12 and, 12.1 to 16.0 were 32.5%, 27.2%, 26.2% and 33.3%, respectively The PR/FAI of 100-150, 151-200, 201-250 and >251 kg body weight were 28.5, 30.5, 29.4 and 31.7%, respectively. In this experiment, The PR/FAI of Parity-0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 were 29.3, 30.1, 28.1, 6.9, 27.4, 29.7, 29.4, 32.0, 50.0 and 20.0%, respectively. The PR/FAI at 0 to 8 hr, 8.1 to 16 hr and 16.1 to 24 hr were 39.1, 41.3 and 41.2%, respectively. The PR/FAI of good, moderate and poor feeding system of cows was 45.1, 33.5 and 21.1%, respectively. It may be concluded that the first service pregnancy rate is not significantly influenced by the breed, age and parity of cows. It is suggested that training on dairying with community veterinary care improves the PR/FAI in Bangladesh . Keywords: Coastal region, risk factors, odd ratio, first service. INTRODUCTION Bangladesh lies in the north-eastern part of South Asia and experiences a tropical environment. It consists of low laying riverine flat land except the hilly regions in the north-east and south-east. The rainfall during monsoon months (July–September) creates a general flooding in the low-laying land. The cattle production system in Bangladesh has been described elsewhere (Shamsuddin et al., 2006, 2007). The national herd of cattle includes the non-descript indigenous/local zebu and their crosses of Friesian or Sahiwal sires. The later Copyright @ 2021: This is an open-access article covers approximately 18% of the national cattle population. Subsistence-type distributed under the terms of the Creative smallholders’ farms own the majority of the animals (3.5 per livestock household) Commons Attribution license which permits that are generally maintained on crop residues and other agricultural by products. unrestricted use, distribution, and reproduction For Bangladesh dairy is an important sector for rural development and poverty in any medium for non commercial use alleviation in Bangladesh but reproductive potentiality of native cattle is very low. (NonCommercial, or CC-BY-NC) provided the Herd profitability is majorly determined by dairy cows reproductive performance original author and source are credited. (LeBlanc, 2007). Four main factors affect reproductive efficiency in dairy herds: days postpartum at first AI, estrous detection rate, pregnancy per AI (P/AI) and pregnancy loss (Risco and Retamal, 2011). Fertility or conception or pregnancy of dairy cows has a great importance to meet today’s expectation of dairy man to get one calf per cow per year. This places an increased emphasis on the need to understand factors that affect fertility/pregnancy, encompassing both herd level management factors and individual cow factors (Hudson, 2011). AI is one of the most important tools or elements of success story behind the genetic improvement (Dutta et al., 1982; Paul et al., 2011). To improve the reproductive efficiency of cattle, Artificial Insemination (AI) using semen from numerous improved zebu and temperate cattle has been introduced for years (Ahmed and Islam, 1987). Despite introduction of AI for long time, still the reproductive efficiency of cattle in Bangladesh is below the satisfactory level. Thus, dairy producers have challenging complaint about a poor reproductive performance in animals using AI (Lemma and Kebede, 2011). The major constraints of reduced efficiency of dairy cattle in Bangladesh are low Conception Rates (CR), a large number of services per conception, prolonged calving to first service interval, poor heat detection (Alam and Ghosh, 1988; Shamsuddin et al., 2001). However, pregnancy rates of cows with AI may be affected by many factors. Major reproductive performance factors encompass both herd-level management factors (such as methods of husbandry, feeding, oestrus detection, semen handling and transition cow management) and cow-level factors (such as age, BCS, post parturient problem, disease events, milk yield and genetics) (Lucy, 2001; Hudson et al., 2012; Lopez-Gatius, 2013; Muller et al., 2014). Tesfaye et al., (2015) stated that BCS and age of the cow, management system and AI service performance affect the reproductive performance of the smallholder dairy farms Paul et al., (2015) reported age, parity, body weight, feeding and milking practice are risk factors for low pregnancy rate/first AI (PR/FAI). The productivity of cows is affected by poor genetics (Rahman et al., 1995), week herd health veterinary services and marketing access (Shamsuddin et al., 2007). Reynolds et al., (1979) reported differences in pregnancy rates due to differences in breeds of cows. Fonseca et al., (1983) found declined conception rate with increasing age of animals. Khan et al., (2015) reported higher conception rate in cows at second and third parity than that of cows at zero parity (nulliparous). Barcellos et al., (1996) reported a higher conception rate in multiparous cows than that in primiparous cows. Md. Shiful Islam, Ashit Kumar Paul, Md. Selim Ahmed, Himangsu Sarker and Dipa Rani Pal (2021); Factors affecting the first service pregnancy rate in cows at the selected coastal region of Bangladesh. IAR J Agri Res Life Sci, 2(1) 15-20 15 Md. Shiful Islam, et al; IAR J Agri Res Life Sci; Vol-2, Iss-1 (Jan-Feb -2021): 15-20. Moreover, Poor feeding practices, lack of reproductive health management and diseases have been demonstrated elsewhere as the causes of poor fertility in Bangladesh (Sarder et al., 1997). These reports emphasize the importance of different factors influencing the post-AI conception rates in cattle. (1-3kg concentrate and 4-5 kg green grass), and iii) good feeding (balanced concentrate & green grass, good feeding (3-3.5kg concentrate & sufficient green grass). Oestrus detection and pregnancy diagnosis Cows generally show oestrus approximately every 21 days (20 days for a heifer). The oestrus was commonly detected by observing the oestrus sign and rectal palpation. Pregnancy was diagnosed by palpation of the uterine contents rectally. Pregnancy diagnosis after insemination can be perform as early as 30 days in heifers and 35 days in cows, although much practice is necessary to be able to determine pregnancy at that stage. BSC (Body condition score) was determined as described by Paul et al., (2011). Most of the people of Bangladesh live in village and having one or more than one cow in each family. (Paul et al., 2011) reported that the major problem of the heifer (both zebu and crossbred) at village areas is low pregnancy rate. There are many reasons behind this problem such as feed crisis, natural calamities, and limited access to veterinary service, negative energy balance, genetic variation and poor body condition leading to non-functional ovaries, which is considered important causes of low pregnancy (Shamsuddin et al., 2001, Paul et al., 2011). But it is most of the time quite difficult to overcome many of these causes in certain situations. However, there is lack of data and information regarding the reproductive performance of cattle at first service pregnancy rate in different coastal areas of Bangladesh. Therefore, the focus on this study is to evaluate the first service pregnancy rate in cows at the selected coastal areas of Bangladesh. Reproductive traits of the inseminated cows After each AI, the technician filled up a prescribed form to record the information of the farm, cow’s age, breed, parity, last calving date, oestrus behaviour and characteristics of genital discharge of cows, and the site of semen deposition at AI. The age of the cow was determined by interviewing the farmer or by dentition when the owner could not provide the correct information. The parity, last calving date and periparturient events (if any) were recorded from farmers’ reports. The body condition scores (BCS) of the cows at AI were recorded into 1–5 scale (Nicholson and Butterworth 1986). Between 60 and 90 days after AI, the pregnancy of the cows was diagnosed by rectal palpation by the veterinarians responsible for each region. Only the cows that were identified correctly and examined for pregnancy were used for analysis. MATERIALS AND METHODS Study Areas The study was conducted during the period from September 2015 to September 2016 at the 10 Upazilas in Barisal district covering Agailjhara, Babuganj, Bakerganj, Banaripara, Barisal Sadar, Gaurnadi, Hizla, Mehendiganj, Muladi and Wazirpur. Statistical analysis The raw data were decoded, entered and sorted accordingly using the MS Excel. The data were then transferred to analytical software SPSS (version 20.0) for doing logistic regression to measure the association and strength of association between the potential influencing factors (Anon, 1996). Data collection For collection of information, a format was used to keep the recorded data. The format contained date, name of farmers and their address, location mark, age, breed, body weight, parity, date of oestrus and date of AI and feeding category. Animal selection and grouping One thousand four hundred thirty one (1431) cows were selected from 10 Upazilas of Barishal district, Bangladesh. It was recorded by checking their record book, collecting information from Upazila Livestock Office and asking the farmer. According to the breed, the cows were divided into Local (L), Cross (C) and Sahiwal (SL). According to the age, the cows were divided into 2.0 to 4.0, 4.1 to 8.0, 8.1 to 12.0 and 12.1 to 16.0 years. Cows were divided into Parity-0 (heifer), Parity-1, Parity-2, Parity-3, Parity-4, Parity-5, Parity-6, Parity-7, Parity-8 and Parity-9. Cows with different body weight were divided into 100 to 150 kg, 151 to 200 kg, 201 to 250 kg and >251 kg. RESULTS AND DISCUSSION The study was conducted from September 2015 to September 2016 at the 10 Upazilas in Barisal district. A total of 1431 cows were used in the experiment for investigating the effect of breed, age, parity, body condition, AI time and feeding category. A descriptive analysis expressed as binary logistic regressions were done to measure the association and strength of association of different factors. The overall first AI pregnancy rate (PR/FAI) was 29.1%. It is partially agreed with Mekonnen et al., (2010) who reported PR/FAI 34.5%. It is markedly lower than that of the study of Paul et al., (2011) who got PR/FAI 42.7%. Feeding and management system Cows were in different feeding system. The cows were divided into i) poor feeding (1 Kg concentrate & no green grass, sufficient straw), ii) moderate feeding 16 Md. Shiful Islam, et al; IAR J Agri Res Life Sci; Vol-2, Iss-1 (Jan-Feb -2021): 15-20. multiple logistic regression results is showed in Table 7. There was no significant (P>0.05) different among the Effect of Breed on PR/FAI The PR/FAI of Local, Cross and Sahiwal breed were group of breed category. 28.3, 30.9 and 20.0%, respectively (Table 1). The respectively (Table 3). The heavy body weight cows had shown better performance. Table1. Effect of Breed on PR/FAI Breed Frequency Pregnant n (%) Local 854 242 (28.3) Cross 557 172 (30.9) Sahiwal 15 3 (20.0) Total 1431 417 (29.1) Table 3. Effects of body weight on PR/FAI Body weight ( Kg ) Frequency Pregnant n (%) 100 - 150 743 212 (28.5) 151 - 200 233 70 (30.5) 201 - 250 395 116 (29.4) >251 60 19 (31.7) The highest (30.9%) first service pregnancy rate was observed in cross cows and lowest (20%) in sahiwal cows, but there was no significant (P>0.24) difference in conception rate among the different genotypes of cows. Gosh (1995) found almost similar results that had no significant difference in first service CR for different genotypes of cows. Gwazdauskas et al., (1975) also reported that they found no significant difference in CR due to genotypic variation of cows. But Reo et al., (1992) observed higher CR of indigenous cows than other genotypic groups. Besides this, Marongiu et al., (2002) reported that CR was significantly (P<0.01) higher in Sarda cows (95%) than Charolasis × Sarda cows (57%). In practices, it is difficult to find out the effect of cow’s genotype on their fertility. Environmental and management conditions those might have more influence on fertility. The cows having BCS 2.75-3.5 (very good condition) had shown better performance than that of others. Lyakov et al., (1977) defined low, intermediate and high categories of BCS for values lower than 2.5, from 2.5 to 3.5, or higher than 3.5, respectively. Saacke et al., (1991) reported that the heavier cows perform than their lighter counterparts. But excessive body weight also reduces the CR in local and cross cows that we find through this study. The relationship between body condition score and production was strong, but, even after adjusting for yield, an unfavourable relationship still exists between body condition score and fertility (Pryce et al., 2001). Body condition score could be used as a management and selection tool to improve reproductive performance. Effect of age on PR/FAI In the experiment the PR/FAI of cows aged on 2.0 to 4.0, 4.1 to 8.0, 8.1 to 12 and, 12.1 to 16.0 were 32.5%, 27.2%, 26.2% and 33.3%, respectively (Table 2). Effect of parity of cows on PR/FAI In this experiment, the first service conception rate was studied from Heifer (Parity-0) to 9th parity. The PR/FAI of Parity-0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 were 29.3, 30.1, 28.1, 6.9, 27.4, 29.7, 29.4, 32.0, 50.0 and 20.0%, respectively (Table 4). The logistic regression was not done in these factors due to marked differences of sample size among the categories. Table 2. Effect of age on PR/FAI Age Frequency Pregnant n (%) 2.0 – 4.0 388 126 (32.5) 4.1 – 8.0 938 255 (27.2) 8.1 -12.0 84 22 (26.2) 12.1 - 16 21 14 (33.3) Table 4. Effect of parity of cows on PR/FAI Number of Parity Frequency Pregnant n (%) Parity-0 (Heifer) 515 141 (29.3) Parity-1 370 110 (30.1) Parity-2 296 87 (28.1) Parity-3 100 29 (6.9) Parity-4 55 16 (27.4) Parity-5 40 15 (29.7) Parity-6 10 4 (29.4) Parity-7 25 8 (32.0) Parity-8 10 5 (50.0) Parity-9 10 2 (20.0) The effect of age on pregnancy rate in the present study was found non-significant (P>0.05) as well as the effect of age on cow fertility was non- significant (P>0.05). The age related findings of this study were in partial agreement with the report of Spalding et al., (1975). They reported a slight increase in the fertility of cow up to 3 to 4 years of age and a decline after 4 years of age. They also found a marked decline in fertility in cows over 7 years of age. De Kruif (1978) observed pregnancy rate following the first insemination to be lower for over 7 years of age. But due to the large number of animal, the rate of pregnancy over 7 year of age has increased. The present study found the parity as non-significant influencing factor in the pregnancy rate of cows. Contrasting to the present finding, Khan et al., (2015) reported higher conception rate in cows at second and third parity than that of cows at zero parity (nulliparous). Moreover, Barcellos et al., (1996) reported a higher conception rate in multiparous cows than that in primiparous cows. Effects of body weight on PR/FAI The PR/FAI of 100-150, 151-200, 201-250 and >251 kg body weight were 28.5, 30.5, 29.4 and 31.7%, 17 Md. Shiful Islam, et al; IAR J Agri Res Life Sci; Vol-2, Iss-1 (Jan-Feb -2021): 15-20. variation in conception rate 58.82, 69.69 and 33.70% There is also report that conception rates in cows at when the cows were inseminated in early, middle and their first three parities are higher than their later late oestrus, respectively. Thus, the effect of time of parities (Zu and Zun, 1997). But during this study we insemination on CR as observed in the present study saw that in later parity, pregnancy rate was higher supported the other previous studies. So, it can be although the number of animals were very few. Further, concluded on the basis of the above results that the Hla et al., (2001) reported an increased conception rate conception rate may be significantly differed due to the with advancing parity from parity 2 up to 6 and then time variation of insemination and the appropriate time declined at parities 7 and 8. In the present study, the of insemination is 11-14 h after the on-set of oestrus. maximum recorded parity of cows was 09 and most of the cows were belonged to 1-3 parities (843 out of Effects of feeding on PR/FAI 1431) which may be considered as the parity of grown The PR/FAI of good, moderate and poor feeding cows. Although no significant variation in pregnancy system of cows was 45.1, 33.5 and 21.1%, respectively rate of cows was obtained among different parity (Table 6). The cows were provided sufficient feed had groups, obtaining lower pregnancy rate (27.4%) in 0 shown better performance. parity (nulliparous) cows supports the earlier finding reported by Khan et al., (2015). Table 6. Effects of feeding on PR/FAI Feeding Frequency Pregnant n (%) Effect of time of AI on PR/FAI Good 208 45.1 Time of insemination during oestrus is one of the Moderate 498 33.5 most important factors influencing conception rate. The Poor 725 21.1 PR/FAI at 0 to 8 hr, 8.1 to 16 hr and 16.1 to 24 hr were 39.1, 41.3 and 41.2%, respectively (Table 5). The cows were provided sufficient feed had shown better performance. The effect of feeding condition on Table 5. Effect of time of AI on PR/FAI fertility is very important. Ghosh et al., (1993); Jalil et Time of AI Frequency Pregnant n (%) al., (1995) indicated that improved feeding has a 0 to 8 hr 96 39.1 positive effect on reproductive performance. The 8.1 to 16 hr 931 41.3 present study demonstrates the significant influence of 16.1 to 24 hr 404 41.2 feeding practices on pregnancy rate. A significantly higher pregnancy rate (45.1%) was found in cows fed with a combination of green grass, straw and Time of insemination during oestrus is one of the most important factors influencing conception rate. concentrate feed than that of cows fed with only straw Gonzalez (1981) stated that the conception rate was (21.1%). The present finding indicates the importance highest (62.58%) when insemination was done at 12 to of daily supplementation of some concentrates in feed 18 hours after the onset of oestrus. Dutta et al., (Dutta et of dairy cows. It is likely that cows fed with a al., 1982) and Bach (Bach, 1983) reported that the CR combination of green grass, straw and concentrate feed is high when insemination is done at middle or late is more balanced diet than that of cows fed with only oestrus. The PR/FAI in 00–08 h (39.1%), 8.1–16 h straw. It is found in a number of studies that nutrition (41.3%) and 16.1–24 h (41.2%) after onset of oestrus. manipulation can result in changes in gonadotrophin From the study, the highest conception rate (41.3) was (GnRH) secretion. The cows deficient in adequate observed when insemination was done between 8.1–16 quantity of balanced feed had reduced pituitary h of oestrus and lowest conception rate (39.1%) when responsiveness to a GnRH challenge (Nolan et al., insemination was done at later than 0–8 hr also clearly 1988). Thus providing a feed with combination of green indicates the CR increased (after the 8th hr of oestrus) grass, straw and concentrate in the present study might with the increasing time of insemination during the have contributed to proper functioning of reproductive oestrus of cows. Das et al., (1990) also reported almost hormones resulting in good rate of pregnancy. similar results, they observed significant (P<0.01) 18 Md. Shiful Islam, et al; IAR J Agri Res Life Sci; Vol-2, Iss-1 (Jan-Feb -2021): 15-20. Table 7. Logistic regression analysis to estimate adjusted odd ratio for the PR/FAI in cows Variables Category Wald P value Odd ratio Age 2.0 – 4.0 2.665 .446 $ 4.1 – 8.0 .062 .804 .887 8.1 -12.0 .451 .502 .726 12.1 - 16 .436 .509 .704 Time of AI 0 to 8 hr .184 .912 $ 8.1 to 16 hr .176 .675 .898 16.1 to 24 hr .005 .945 .991 Body weight 100 - 150 .500 .919 $ 151 - 200 .377 .539 .831 201 - 250 .153 .695 .882 >251 .383 .536 .826 Breed Local 1.276 .735 $ Cross .000 .999 4.199 Sahiwal .000 .999 4.710 $ indicates the base category of compares. CONCLUSIONS It may be concluded that the first service pregnancy rate is not significantly influenced by the breed, age and parity of cows. Good feeding practice with combination of green grass, straw and concentrate feed improves the pregnancy rate in cows. 10. 11. ACKNOWLEDGEMENT The author expresses his deepest of gratitude to Research and Training Center (RTC), Patuakhali Science and Technology University, Bangladesh for partial financial support. 12. REFERENCES 13. 1. 2. 3. 4. 5. 6. 7. 8. 9. Ahmed, J.U., & Islam, T.S. (1987). Cattle breeding programme through AI in Bangladesh. AI extension project report, central cattle breeding station, Savar, Dhaka, Bangladesh. Journal of Animal Science, 8, 33-54. Alam, M.G.S., & Ghosh, A. (1988). Reproductive performance in cows: its relation to parity and season. Bangladesh Veterinary Journal, 22, 51-61. Anon 1996 SYSTATÒ 6.0 for windosÒ: statistics, SPSS inc, Michigan Avenue, Chicago IL USA. Bach, S. (1983). Possibility of determination of time of insemination at spontaneous oestrus. Animal Breeding Abstact, 51, 6122. Barcellos, J.O.J., Silva, M.D.D.A., & Silva, J.L.C.D.A. (1996). Effects of early weaning on conception rate in Santa Gertrudis cows. Economic Ecological Rurales, 96, 39-47. Das, S.C., Ahmed, J.U., & Alam, M.G.S. (1990). Conception rate in zebu cows using frozen sahiwal semen. Bangladash Veterinary Journal, 24-26, 90-93. De Kruif, A. (1978). Factors influencing the fertility of a cattle population. Journal of Reproduction and Fertility, 54, 507-518. Dutta, J.C., Kakati, B.N., Rajkonwar, C.K., & Borgohain, B.N. (1982). Effect of age of semen on conception rate in cattle under field conditions. Indian Veterinary Journal, 57, 758-761. Fonseca, F.A., Britt, J.H., McDaniel, B.T., Wilk J.C., & Rakes, A.H. (1983). Reproductive traits of Holsteins and Jerseys. Effects of age, milk yield and clinical abnormalities on involution of cervix and uterus, ovulation, estrous cycles, detection of estrus, conception 14. 15. 16. 17. 18. 19. 19 rate and days open. Journal of Dairy Science, 66, 11281147. Ghosh, A., Alam, M.G.S., & Akbar, M.A. (1993). Effect of urea-molasses-mineral blocks supplementation in postpartum ovarian activity in zebu cows. Animal Reproduction Science, 31, 61 -67. Ghosh, D.K. (1995). Economic traits of cross breed cattle in small dairy enterprises of Gazipur district. M.S. Thesis, Department of Physiology, Bangladesh Agricultural University, Mymensingh. Gonzalez, (1981). Performance recording of lactating local crossbred cows and buffaloes of various exotic breed blood levels under farmer's management in the western hills. Working paper Liumle Agricultural Research Center, 98, 1 -14. Gwazdauskas, F.C, Wilcox, C.J., & Thatcher, W.W. (1975). Environmental and managemental factors affecting conception rate in a subtropical climate. Journal of Dairy Science, 58, 88-92. Hla, U.T., Myatt, U.A., Kyi, D.S.S., & Win, U.Y.H. (2001). Improvement of cattle production in myanmar through the use of progesterone RIA to increase efficiency and quality of artificial insemination services. Proceedings of Final Research Co-ordination Meeting on Radioimmunoassay and Related Techniques to Improve Artificial Insemination Programs for Cattle Reared under Tropical and Sub-tropical Conditions: (1999, May 10-14) Uppsala, Sweden, pp. 45-50. Hudson, C. (2011). Understanding the factors affecting dairy cow fertility. Veterinary Record, 168, 299-300. Hudson, C.D., Bradley, A.J., Breen, J.E., & Green, M.J. (2012). Associations between udder health and reproductive performance in United Kingdom dairy cows. Journal of Dairy Science, 95, 3683-3697. Jalil, M.A., Sarker, N., Paul, D.C., & Khan, A.A. (1995). Status of existing husbandry practices of dairy cattle at Manikganj, Bangladesh. Bangladesh Journal of Animal Science, 24, 71 -80. Khan, M.R.K., Uddin, J., & Gofur, M. R. (2015). Effects of age, parity and breed of the cows on conception rate and number of services per conception in artificially inseminated cows in Bangladesh. Journal of Bangladesh Livestock, 1, 1-4. LeBlanc, S. (2007). Economics of improving reproductive performance in dairy herds. Advanced Dairy Technology, 19, 201-214. Md. Shiful Islam, et al; IAR J Agri Res Life Sci; Vol-2, Iss-1 (Jan-Feb -2021): 15-20. restricted suckling frequency on postpartum reproductive and productive performance of Sarda and Charolais × Sarda beef cows. Livestock Production Science, 77, 2-3, 339–48. 25. Mekonnen, T., Bekana, M., & Abayneh, T. (2010). Reproductive performance and efficiency of artificial insemination smallholder dairy cows/heifers in and around Arsi-Negelle, Ethiopia. Livestock Research for Rural Development, 61(22), Retrieved July 25, 2013, from http://www.lrrd.org/lrrd22/3/meko22061.htm 26. Muller, C.J.C., Potgieter, J.P., Cloete, S.W.P., & Dzama, K. (2014). Non-genetic factors affecting fertility traits in South African Holstein cows. South African Journal of Animal Science, 44, 54-63. 27. Nicholson, M.J., & Butterworth, M.H. (1986). A Guide to Condition Scoring of Zebu Cattle. International Livestock for Africa, Addis Ababa, Ethopia. pp. 29. 20. Lemma, A., & Kebede, S. (2011). The effect of mating system and herd size on reproductive performance of dairy cows in market oriented urban dairy farms in and around Addis Ababa. Revue Medecine Veterinaire, 162, 526-530. 21. Lopez-Gatius, F. (2013). Approaches to increase reproductive efficiency in artificially inseminated dairy cows. Animal Reproduction, 10, 143-147. 22. Lucy, M.C. (2001). Reproductive loss in high-producing dairy cattle: Where will it end. Journal of Dairy Science, 84, 1277-1293. 23. Lyakov, V.V., Animnov, R.M., & Rakhamnov, M. (1977). Breeding of Cattle. Animal Breeding Abstract, 47, 6021. 24. Marongiu, M.L., Molle, G., SanJuan, L., Bomboi, G., Ligios, C., Sanna, A., Casu, S., & Diskin, M.G. (2002). Effects of feeding level before and after calving, and 20