بررسی اثر همخونی بر افزایش وزن روزانه و نسبت کلیبر در گوسفند نژاد مهربان

نوع مقاله : علمی پژوهشی- ژنتیک و اصلاح دام و طیور

نویسندگان

1 دانشگاه گیلان

2 دانشگاه تهران

3 دانشگاه تربیت مدرس

چکیده

هدف از این پژوهش ارزیابی اثر همخونی بر افزایش وزن روزانه و نسبت کلیبر در گوسفند مهربان بود. اطلاعات داده‌ای (مشتمل بر 6550 رکورد) و شجره حیوانات مورد استفاده طی سال‌های 1374 تا 1390 به وسیله سازمان جهاد کشاورزی استان همدان جمع‌آوری شده بود. صفات مورد مطالعه شامل میانگین افزایش وزن روزانه از تولد تا شیرگیری (ADGa)، از شیرگیری تا شش ماهگی (ADGb)، از شیر گیری تا نه ماهگی (ADGc) و از شیر گیری تا یک سالگی (ADGd) و به طور متناظر نسبت‌های کلیبر مربوطه (KRa، KRb، KRcو KRd) بود. حیوانات با توجه به ضرایب همخونی به دست آمده از شجره به سه گروه دسته‌بندی شدند: گروه اول شامل حیوانات غیر همخون و گروه دوم و سوم شامل حیوانات همخون بودند. برای ویرایش داده‌ها از نرم افزار Foxpro، برای برآورد اثر همخونی بر صفات از نرم افزار SAS استفاده شد و افت همخونی به صورت رگرسیون خطی با استفاده از رویه Reg نرم افزارSAS محاسبه شد. روند معنی‌دار ضرایب رگرسیون ADGa، KRa، ADGb، KRb، ADGd و KRd از همخونی همه بره‌ها به ازای افزایش 1% همخونی مشاهده شد. ضریب رگرسیون تمام صفات بجز KRc بر همخونی بره‌های تک قلو و صفات ADGa و KRa بر همخونی بره‌های دو قلو معنی‌دار بود. با توجه به جنس بره، ضریب رگرسیون تمام صفات بجز ADGc و ADGd بر همخونی بره‌های نر و ADGc و KRd بر همخونی بره‌های ماده معنی‌دار بود. نتایج این پژوهش نشان می‌دهد که همخونی بر میانگین افزایش وزن روزانه و نسبت کلیبر در گوسفند نژاد مهربان مؤثر بوده است و معنی‌دار و مثبت برآورد شد.

کلیدواژه‌ها


عنوان مقاله [English]

Inbreeding Effects on Average Daily Gain and Kleiber Ratio in Mehraban Sheep

نویسندگان [English]

  • Roya Yavarifard 1
  • Navid Ghavi Hossein-Zadeh 2
  • Abdol Ahad Shadparvar 3
1 University of Guilan
2 University of Tehran
3 Tarbiat Modares University
چکیده [English]

Introduction Along with increase in genetic progress, maintaining genetic diversity in any population is very important to adapt with the economic and environmental changes in the future and ensure long-term response to selection for traits that are very important. Intensive use of a few breeding animals, where the selection intensity is high, could result in greater rates of inbreeding in the population. Therefore, a small number of seedstock, with a strong family relationship, is responsible for the maintenance of almost the whole genetic pool in the population. This is an aspect of great influence in the genealogical analysis of a population structure, because of its effect on the probability of genes lost between generations and the consequent reduction in genetic variability. The unavoidable mating of related animals in closed populations leads to accumulation of inbreeding and decreased genetic diversity. Measurement of the effect of inbreeding on these traits is important in order to estimate the magnitude of changes associated with increases in inbreeding although direct selection for lower maintenance requirements is difficult. Some populations may show a very pronounced effect of increased inbreeding for a trait, whereas others may not display much of an effect. The rate of inbreeding needs to be limited to maintain diversity at an acceptable level, so that genetic variation will ensure that future animals can respond to changes in the environment and to selection. Without genetic variation, animals cannot adapt to these changes. Commonly, negative inbreeding effects, or inbreeding depression, are thought to most frequently occur because of an increase in frequencies of recessive alleles that adversely affect the traits of interest. The increased frequency of recessive alleles leads to a larger number of individuals that are homozygous for the recessive alleles, whereas in non-inbred populations, the recessive allele would more frequently be masked by an advantageous dominant allele. Kleiber ratio (KR) allows us to identify efficient animals. This ratio, defined as growth rate/ metabolic weight (body weight0.75), was suggested for measuring growth efficiency. One of the most important breeds of Iranian sheep is Mehraban sheep which is reared in Hamedan province. This breed is adapted to harsh climate and rocky environments in the western regions of Iran. The Mehraban is a fat-tailed carpet wool sheep with light brown, cream or grey color, dark face and neck and primarily used for meat production. The objective of this study was to evaluate the inbreeding effects on daily weight gain and Kleiber ratio in Mehraban sheep.
Materials and Methods Data and pedigree information used in this research were collected from 1994 to 2011 in Jihad Agriculture Organization of Hamedan province. Studied traits were average daily gains from birth to weaning (ADGa), average daily gain from weaning to 6 months (ADGb), average daily gain from weaning to 9 months (ADGc), average daily gain from weaning to yearling (ADGd) and corresponding Kleiber ratios (KRa, KRb, KRc and KRd). All animals were grouped into three classes according to their inbreeding coefficients: the first class included non-inbred animals (F=0) and the second and third classes included inbred animals (0 < F < 0/05 and F≥0/05, respectively). In this study, the Foxpro software was used for editing data set, the SAS software was used for estimating inbreeding effect on the traits, and the Reg procedure of SAS software was used for estimating inbreeding depression.
Results and Discussion Significant regression coefficients ADGa, KRa, ADGb, KRb, ADGd and KRd on inbreeding of all lambs were observed for 1% increase of inbreeding. According to the birth type, the regression coefficient of all traits except KRc on inbreeding of single-born lambs and ADGa and KRa on inbreeding of twin-born lambs was significant for a 1%. increase in inbreeding. According to lamb sex, the regression coefficient of all traits except ADGd and ADGc on inbreeding of male lambs and ADGc and KRd on inbreeding inbreeding of female lambs was significant for a 1% increase in inbreeding.
The results showed both significant and non-significant effects of inbreeding on daily weight gain and kleiber ratio traits. The results of this study showed that inbreeding level of over 90% of animals was between 0 and 50%. These results indicate multiple use of a small number of sires in the herd, also the lack of use of mating programs designed for prevent high levels of inbreeding in Mehraban sheep.
Conclusion The results showed positive and significant effects of inbreeding on average daily gains and Kleiber ratios in Mehraban sheep.

کلیدواژه‌ها [English]

  • Average daily gain
  • Inbreeding
  • Kleiber ratio
  • Mehraban fat-tailed sheep
1- Aghaali Gamasaee, V., S. H. Hafezian., A. Baneh., H. Ahmadi., A. Farhadi, and A. Mohamadi. 2010. Estimation of genetic parameters for body weight at different ages in Mehraban sheep. African Journal of Biotechnology, 9(32): 5218-5223.
2- Analla, M., J. M. Montilla, and J. M. Serradilla. 1998. Analyses of lamb weight and ewe litter size in various lines of Spanish Merino sheep. Small Ruminant Research, 29: 255-259.
3- Barczak, E., A. Wolc., J. Wojtowski., P. Slosarz, and T. Szwaczkowski. 2009. Inbreeding and inbreeding depression on body weight in sheep. Journal of Animal and Feed Science, 18: 42-50.
4- Bedier, A. A., N. Z. Younis., E. S. E. Galal, and M. M. Mokhtar. 1992. Optimum ewe size in desert Barki sheep. Small Ruminant Research, 7: 1-7.
5- Boichard, D., L. Maignel, and E. Verrier. 1997. The value of using probabilities of gene origin to measure genetic variability in a population. Genetics Selection Evolution, 29: 5-23.
6- Dario, C, and G. Bufano. 2003. Efecto de la endogamia sobre la produccion lactea en la raza ovina Altamurana (Effect of inbreeding on milk production in Altamurana sheep breed). Archivos de Zootecnia, 52:401-404.
7- Falconer, D. S. 1989. Introduction to Guantitative Genetics. 3rd edition. Longman Group (FE) Ltd, England.
8- Ercanbrack, S. K, and A. Knight. 1991. Effects of inbreeding on reproduction and wool production of Rambouillet, Targhee, and Columbia ewes. Journal of Animal Science, 69: 4734-4744.
9- Ghavi Hossein Zadeh, N. 2013. Inbreeding Effects on Average Daily Gains and Kleiber Ratios in Iranian Moghani Sheep. Iranian Journal of Applied Animal Science, 3(3): 545-551. (In Persian).
10- Hussain, A., P. Akhtar., S. Ali., M. Younas, and M. Shafiq. 2006. Effect of inbreeding on pre-weaning growth traits in Thalli sheep. Pakistan Veterinary Journal, 26(3): 138-140.
11- Hussain, A., P. Akhtar., S. Ali., M. Younas, and K. Javed. 2006. Inbreeding effects on post-weaning growth traits of Thalli sheep in Pakistan. Pakistan Journal of Agricultural Sciences, 43(1-2): 89-92.
12- Kleiber, M. 1947. Body size and metabolic rate. Physiolological Review, 27: 511–541.
13- Khan, M., S. Ali., A. Hyder, and A. I. Chatta. 2007. Effect of inbreeding on growth and reproduction traits of Beetal goats. Archives Animal Breeding, 50: 197-203.
14- Lamberson, W. R, and D. L. Thomas. 1984. Effects of inbreeding in sheep: a review. Animal Breeding Abstracts, 52: 287-297.
15- Mohammadi, K., A. Rashidi., M. S. Mokhtari, and M. T. BeigiNassiri. 2011. The estimation of (co)variance components for growth traits and Kleiber ratios in Zandi sheep. Small Ruminant Research, 99: 116-121.
16- Mirza Mohammadi, A., M. Vatankhah, and M. Jafari. 2010. Evaluate the effects of inbreeding on pre-weaning growth traits and survival of lamb in Black Iran sheep. Iranian Journal of Animal Science, 25: 15-24. (In Persian).
17- Negussie, E., S. Abegaz, and J. E. O. Rege. 2002. Genetic trend and effects of inbreeding on growth performance of tropical fat-tailed sheep. Pages 25-35 in Proc. 7th World Congress Genetics Applied to Livestock Production, Montpellier, France.
18- Norberg, E, and A. C. Sorensen. 2007. Inbreeding trend and in-breeding depression in the Danish populations of Texel, Shropshire, and Oxford down. Journal of Animal Science, 85: 299-304.
19- Pedrosa, V. B., Jr. M. L. Santana., P. S. Oliveira., J. P. Eler, and J. B. S. Ferraz. 2010. Population structure and inbreeding effects on growth traits of Santa Inês sheep in Brazil. Small Ruminant Research, 93: 135-139.
20- Rashidi, A., S. C. Bishop, and O. Matika. 2011. Genetic parameter estimates for pre-weaning performance and reproduction traits in Markhoz goats. Small Ruminant Research, 100: 100-106.
21- Sargolzaei, M., H. J. Iwaisaki, and J. Colleau. 2006. CFC: A tool for monitoring genetic diversity. Page 27 in Proc. 8th World Congress on Genetics Applied to Livestock Production. Belo Horizonte, Brazil.
22- SAS Institute. 2002. SAS User’s Guide v. 9.1. Statistics. SAS Institute, Inc., Cary, NC.
23- Sawalha, R. M., J. Conington., S. Brotherstone, and B. Villanueva. 2007. Analyses of lamb survival of Scottish Blackface sheep. Animal, 1: 151–157.
24- Scholtz, M. M., and C. Z. Roux. 1988. The Kleiber ratio (growth rate/metabolic mass) as possible selection criteria in the selec-tion of beef cattle. Pages 373-375 in Proc. 3rd World Cong. on Sheep and Beef Cattle Breed, Paris, France.
25- Selvaggi, M., C. Dario., V. Peretti., F. Ciotola., D. Carnicella, and M. Dario. 2010. Inbreeding depression in Leccese sheep. Small Ruminant Research, 89: 42-46.
26- Souri, M. and E. Nourian sarvar. 2006. Manual of Sheep Breeding in Various Breeds. Razi University Press, Kermanshah, Iran. (In Persian).
27- Tedeschi, L. O., D. G. Fox., M. J. Baker, and D. P. Kirschten. 2006. Identifying differences in feed efficiency among group-fed cattle. Journal of Animal Science, 84: 767-776.
28- Van Wyk, J. B., M. D. Fair, and S. W. P. Cloete. 2009. Case study: the effect of inbreeding on the production and reproduction traits in the Elsenburg Dormer sheep stud. Livestock Science, 120: 218-224.
29- Weigel, K. A. 2001. Controlling inbreeding in modern breeding programs. Journal of Dairy Science, 84: 177-184.
30- Yavarifard, R., N. Ghavi Hossein-Zadeh, and A. A. Shadparvar. 2014. Population genetic structure analysis and effect of inbreeding on body weights at different ages in Iranian Mehraban sheep. Journal of Animal Science and Technology, 56: 31-40.
31- Zamani, P, and H. Mohammadi. 2008. Comparison of different models for estimation of genetic parameters of early growth traits in the Mehraban sheep. Journal of Animal Breeding and Genetics, 125: 29-34.