www.ijasvm.com IJASVM InternationalJournalofAgricultural SciencesandVeterinaryMedicine ISSN:2320-3730 Vol.5,No.2,May2017 E-Mail:editorijasvm@gmail.com oreditor@ijasvm.comm@gmail.com
Int. J. Agric.Sc & Vet.Med. 2017 Siddalingamurthy H K et al., 2017 Research Paper ISSN 2320-3730 www.ijasvm.com Vol. 5, No. 2, May 2017 2017 www.ijasvm.com. All Rights Reserved ASSESSMENT OF SEX RATIO IN MANDYA SHEEP UNDER FARM CONDITION Siddalingamurthy H K 1*, Manjunatha S S 2 and Sreesujatha R M 3 *Corresponding Author: Siddalingamurthy H K, lricnag@gmail.com Data on 1505 lambing records were collected over a period of seven years from 2010 to 2016 for establishing the sex ration in Mandya sheep maintained at LRIC (S), Nagamangala, Mandya district, Karnataka state. The overall sex ratio was found to be 51.30% male lambs and 48.70% female lambs. The chi square value confirmed that the overall sex ratio in Mandya sheep is not significantly different from the hypothetical value of 50% males and 50% females. Season of birth, year of birth, month of birth, parity and ewe age had non significant effect on the sex ratio and confirmed that these non-genetic factors does not influence the sex ratio in Mandya sheep. Keywords: Mandya sheep, Sex ratio, Non-genetic factors INTRODUCTION Sheep breeds of Karnataka are small to medium in size and are raised mainly for mutton purpose. Although some of the breeds yield wool, it is of very low carpet type. Mandya sheep has been acclaimed to be popular indigenous breed, well known for best meat quality compared to all other Indian meat type sheep breeds which is known for its meaty conformation and palatability of meat due to its marbling quality (Bhatia and Arora, 2005). Usually farmer prefers more female lambs than the male lambs to increase their flock size for further production. In the home tract area of Mandya sheep farmers prefers more male lambs than female lambs as the male lambs fetches more prices due to more demand from the public to propagate this genetic material inside and outside Karnataka. Another reason for demand of more male lambs is due to religious practice of slaughtering of Rams on several festive occasions. In this context study was undertaken to assess sex ratio and non-genetic factor affecting sex ratio in Mandya sheep maintained at farm management conditions. MATERIALS AND METHOD Data on 1505 lambing records were collected over a period of four years from 2010 to 2016 for establishing the sex ratio in Mandya sheep maintained at Livestock Research and Information 1 Associate Professor and Head, LRIC(S), KVAFSU, Nagamangala, Mandya (Dist.), Karnataka 571432, India. 2 Assistant Professor, LRIC(S), KVAFSU, Nagamangala, Mandya (Dist.), Karnataka 571432, India. 3 Research Associate, LRIC(S), KVAFSU, Nagamangala, Mandya (Dist.), Karnataka 571432, India. 37
Centre (Sheep), Nagamangala. All the animals were maintained at the uniform farm management conditions. The ewes were bred in all around the year, hence the season of lambing were classified into three seasons namely, season I (June to September), Season II (October to January) and Season III (February to May). Sex ratio was deliberated as the whole percentage of male and female lambs born among all normal births at the farm. To test significant difference of sex ratio between observed frequency and expected frequency of sex ratio, the following statistical model was used and the chi square value is compared with the table value at (r-1)(c- 1) df at 0.05 level of significance (Khan and Khanum, 1994) using SAS 9.3. X2 = (f0-fc)2/fe Fo = observed frequency Fe = expected frequency RESULTS AND DISCUSSION Out of total 1505 normal births occurred during the period under study (seven years) from 2010-2016, 772 lambs were male and 733 were females forming a percentage of 51.30% and 48.70% respectively (Table 1). The overall percentage of males recorded in this study is tallied closely with the reports of Purushotham (1972) in Mandya and Nellore breed (51.98%), Siddalingamurthy (2001) in Mandya Sheep (52.31%) and Soundararajan and Shivakumar (2011) in Madras Red Sheep (50.93%). In contrast to this result Sundararaman and Eswaran (1991) reported lower values of 48.0% in Nilgiri and Naidu (1992) reported 48.84% in Nellore breed. However Krishna (1966) in Nilgiri breed (54.68%) reported slightly higher value than the estimate obtained in this study. In contrast, Tailor et al. (2008) reported 1:1 male to female sex ratio in Sonadi sheep. The overall percentage of male lambs recorded in Mandya sheep was 51.30% (Table 1). The highest percentage of male lambs were recorded during the year 2010 (62.50%) and that of the lowest during the year 2014 (47.49%) (Table 2). Variations observed in different year from 2010 to 2016 in the percentage of males Table 1: Overall Sex Ratio of Mandya Lambs Gender Male 772 51.3 0.3148 Female 733 48.7 Table 2: Year-Wise Sex Ratio of Mandya Lambs Year Lambing 2010 4.78 45 27 62.5 37.5 2011 8.5 72 56 56.25 43.75 0.2574 2012 15.28 117 113 50.87 49.13 2013 21.4 171 151 53.11 46.89 2014 19.87 142 157 47.49 52.51 2015 16.08 122 120 50.41 49.59 2016 14.09 103 109 48.58 51.42 38
Table 3: Season-Wise Sex Ratio of Mandya Lambs Season Lambing I (Jun-Sep) 27.44 215 198 52.06 47.94 II (Oct-Jan) 44.72 340 333 50.52 49.48 0.8611 III (Feb-May) 27.84 217 202 51.79 48.21 Table 4: Month-Wise Sex Ratio of Mandya Lambs Month Lambing January 6.91 59 45 56.73 43.27 February 7.44 53 59 47.32 52.68 March 8.04 64 57 52.89 47.11 April 5.45 38 44 46.34 53.66 May 6.91 62 42 59.62 40.38 June 5.45 39 43 47.56 52.44 July 6.45 60 37 61.86 38.14 0.2236 August 5.78 49 38 56.32 43.68 September 9.77 67 80 45.58 54.42 October 15.75 117 120 49.37 50.63 November 9.17 68 70 49.28 50.72 December 12.89 96 98 49.48 50.52 Table 5: Parity-Wise Sex Ratio of Mandya Lambs Parity Lambing 1 16.48 121 127 48.79 51.21 2 21.33 166 155 51.71 48.29 3 21.66 168 158 51.53 48.47 4 17.81 138 130 51.49 48.51 0.9542 5 11.36 92 79 53.8 46.2 >6 11.36 87 84 50.88 49.12 were non-significant. Similar findings were also reported by Shri et al. (1977) in Nali ewes and Siddalingamurthy (2001) in Bandur ewes. The percentage of male lambs born during the different lambing seasons (Table 3) June to September, February to May and October to 39
Table 6: Effect of Ewe Weight on Sex Ratio in Mandya Lambs Ewe weight Lambing <20 5.51 47 36 56.63 43.37 20-24 39.93 302 299 50.25 49.75 25-29 45.85 354 336 51.3 48.7 0.7276 30> 8.7 69 62 52.67 47.33 January were 27.44%, 27.84% and 44.72%, respectively. Based on the frequency of lambing, October to January was classified as main lambing season while February to May and June to September were off lambing season and lean lambing season, respectively. The number of lambs born in each year comparatively was less during the lean lambing season June to September. Variations observed in different seasons, in the percentage of males born were not significant statistically. Similar observations were also reported by Ganesa and Raman (1994) in Madras Red, Siddalingamurthy (2001) in Bandur ewes and Sundararaman and Eswaran (1991) in Nilgiri breed. Lambs born during different months were analyzed for effect of month on sex ratio (Table 4). The highest percentages of male lambs born during the month of July which was recorded to be 61.86% and the lowest percentage of male lamb was recorded for the month of September which is 45.58. Whereas, Soundararajan and Sivakumar (2011) observed the highest percentage of male births (62.07%) during the month of October and the lowest percentage of male births (20%) during the month of May in Madras Red Sheep. The highest percentage of male birth was found to be 53.80% in the fifth parity and the lowest percentage of male was found to be 48.79% at first parity (Table 5). However, the variations observed in different parities in the percentage of males were not significant statistically. This observation is in par with the findings of Macedo et al. (2007) in Pelibuey Lambs and Kent (1996) in Suffolk cross breed lambs. This result indicating that the tendency of sex of lamb favoured towards male lambs in the middle phase of reproductive life of Mandya sheep. The effect of ewe body weight on sex ratio was analysed ( Table 6). T her e was no significant effect between the ewe body weight on sex ratio of lambs. The number of male lamb born was high compared to female for the ewe weighing less than 20 kg than other three groups but t he dif f erence was non- sig nif icant statistically. CONCLUSION In conclusion, non genetic factors such as Year of birth, Season of birth, month of birth, parity and ewe body weight are not showing significant effect on sex ratio and the chi square value confirms that the overall sex ratio was not significantly different from the theoretical value of 50 males: 50 females. As the ratio was equal in Mandya sheep, it was possible to conclude that there was hardly any differential intra uterine survivability with respect to sex in Mandya sheep enumerated in this study. 40
ACKNOWLEDGMENT This study was the part of Indian Council of Agriculture Research, New Delhi funded project entitled Mega Sheep Seed Project on Mandya Sheep. We acknowledge the coordinating support from Central Sheep and Wool Research Institute, Avikanagar, Rajasthan and the institutional support and facilities provided by the Karnataka Veterinary, Animal and Fisheries Sciences University, Bidar, Karnataka. REFERENCES 1. Bhatia S and Arora R (2005), Biodiversity and Conservation of Indian Sheep Genetic Resources An Overview, Asian-Aust. J. Anim. Sci., Vol. 18, No. 10, pp. 1387-1402. 2. Ganesha Kale D and Raman K S (1994), Sex Ratio Twinning Stillbirth and Abortions in Madras Red and Mandya Breeds of Sheep, Indian Vet. J., Vol. 71, No. 12, pp. 1195-1197. 3. Kent J P (1996), Birth Sex Ratios in Sheep Over 10 Lambing Seasons: Year 10, the Effects of Litter Size, Seasonal Factors and Ageing, The Irish Journal of Psychology, Vol. 17, No. 1, pp. 60-70. 4. Khan I A and Khanum A I (Eds.) (1994), Fundamentals of Biostatistics, Ukaaz Publications, Hyderabad, Andhra Pradesh. 5. Krishna Rao C (1966), Studies on Reproduction in Indian Breeds of Sheep- Bannur and Nilgiri Breeds, Indian Vet. J., Vol. 43, pp. 130-133. 6. Macedo R, Arredondo V, Casarez E, Esperon A E and Hummel J D (2007), Offspring Sex Proportion and Lamb Competition During Gestation and Lactation in Prolific Pelibuey Lambs Under Intensive Management, Livestock Research for Rural Development, Vol. 19, Article No. 188. 7. Naidu N M (1992), Sex Ratio in Nellore and Decanni Breeds of Sheep, Cheiron, Vol. 21, pp. 91-92. 8. Purushotham C H (1972), Comparative Study of the Production and Reproduction Traits in Nellore and Mandya Sheep, M.V.Sc., Dissertation, Andhra Pradesh Agricultural University, Hyderabad, Andra Pradesh. 9. Shri Ram, Kamal Kishore and Chopra S C (1977), Causes of Variation in Sex Ratio in Sheep, Livestock Advisor, Vol. 11, p. 23. 10. Siddalingamurthy H K (2001), Evaluation of Bandur Sheep in Mandya District of Karnataka for Economic Traits, M.V.Sc., Dissertation, University of Agricultural Sciences, Bangalore, Karnataka. 11. Soundararaja C and Sivakumar T (2011), Factors Affecting Sex Ration in Madras Red Sheep, Tamilnadu J. Veterinary & Animal Sciences, Vol. 7, No. 1, pp. 12-15. 12. Sundararaman M N and Eswaran B M (1991), Studies on Sex Ration in Sheep, Cheiron, Vol. 20, No. 5, pp. 167-168. 13. Tailor S P, Lokesh Gupta and Nagda R K (2008), Lambing Pattern and Sex Ratio in Sonadi Sheep Reared by the Farmers in Semi-Arid Conditions of Rajasthan, Indian Journal of Small Ruminants, Vol. 14, No. 2, pp. 279-282. 41