جستجوی مقالات مرتبط با کلیدواژه « crossbreeding » در نشریات گروه « علوم دام »

The purpose of this project is to investigate the characteristics of birth weight, three-month weight, weight gain from birth to three months, maturity weight and milk production of female goats during the years 2018 to 2022 in Kerman province, related to native goats (BB) and their hybrids with the Saanen breed, respectively,with 50 (S1 B), 75 (S2B) and 87.5 (S3B) percent of the Saanen breed gene. A number of 9 herds selected in Kerman province. The total number of female goats were 2089, of which 1909 were fertile and 2584 goats were born. Data storage, editing, and preparation were performed using Excel 2013 software. After editing and preparing the recorded information, the effect of fixed factors on variables and data analysis was performed using the Spss software. Birth weight, milk weight, and daily weight gain from birth to milk intake in crossbred kids were higher than in purebred kids. Crossbred goats had a higher milk production weight than native goats. In native goats, a fertility rate of 85% was obtained, while in those inseminated with Saanen breed, the fertility rate was 92%. The weaning rate in those inseminated with Saanen breed was higher than in native goats (137% vs. 111%). Also, the reproductive ability in those inseminated with Saanen breed was higher.

The aim of this study was to investigate the growth performance, water consuming pattern, digestibility, and carcass traits of Lori-Bakhtiari (LORI) and Romanov-Lori-Bakhtiari (CROSSbred) lambs under water restriction conditions. Twenty lambs (10 heads per genotype) with an average weight of 31±2.5 and an age of 8±2 months were used in four treatments with 5 replications in each in a completely randomized design with 2×2 factorial. Water-restricted (WR) lambs had free access to water for only one hour a day. All lambs were slaughtered after six weeks. Feed intake, daily weight gain and final weight were not affected by genotype and access to water, while water intake (p=0.001) and water to feed ratio (p=0.02) were significantly dropped with water restriction. Water-restricted lambs consumed almost 90 percent of their water intake in the first five minutes. Nutrients digestibility was not affected by the treatments, but the amount of fecal dry matter was significantly high in water restricted groups (p=0.03). Carcass weight and yield were not affected by the treatments, but the percentage and weight of tails in the CROSSbred lambs were lower (p≤0.0001), but part of this decrease was compensated by higher fat thickness (p=0.05) and visceral fat (p=0.03).  The overall results of this study showed that genotype and water restriction did not significantly affect growth performance, so CROSSbred lambs can be used in water restricted area.

Crossbreeding as the fastest approach to take advantage of difference between breeds, can be an effective method to improve the efficiency of meat production in sheep. The aim of the present study is to compare Balochi lambs with the crossbred obtained from Baluchi ewes with Kurdi and Karakul rams.

In order to investigate the effect of crossbreeding on the weight performance of lambs up to weaning and the fattening period and carcass composition, three genetic groups including pure Baluchi (BB) lambs, Karakul × Baluchi (GB) and Kurdi × Baluchi (KB) crosses were used. The ewes were mated in groups of 50 and each group with 2 rams. The number of 27 purebred and crossbred male lambs were used in the form of three treatments with three replications and three lambs per replication. Data were analyzed using GLM procedure of SAS software.

The results showed that lambs from Karakul rams had the highest birth weight and lambs from Baluchi rams had the lowest birth weight (4.80 and 3.95 kg, respectively). Lambs from karakul rams had higher daily gain (260g /day) before weaning than other lambs (p<0.05).  The highest and lowest dry matter intake were in the GB group (1250g /day) and the BB group (950 g / day), respectively. The highest daily gain in GB group and the lowest in BB group were 169.2 and 93.8 g / day, respectively (p <0.05). The genetically groups had significant effect on cold and hot carcass weights (p<0.05). The effect of crossbreeding on fat thickness, fat-tail, and shank was significant (p<0.05).

Due to the suitable reproductive performance in using Karakul ram as a paternal breeding base and optimal performance in growth rate, feed consumption, conversion ratio in the pre-weaning and post-weaning periods as well as carcass characteristics including hot and cold carcass weight and less tail compared to other crossbreds used in this study, it is probably more appropriate to use Karakul rams to produce crossbred lambs.

The objective of this study was to compare growth performance, birth and weaning body weights, and survivability between purebred Balouchi (n=53) and crossbred Balouchi×Romanov (n=114) lambs. In addition, carcass characteristics (n=24) were determined. Balouchi ewes were inseminated with Romanov semen to produce crossbred lambs. All experimental lambs were weaned at 77 d of age and slaughtered at 10 months of age. Birth body weight of the purebred Balouchi lambs was significantly greater than for the crossbred lambs (3.75 vs. 3.56 kg, P<0.01). However, weaning body weight and average daily gain from birth until weaning and slaughter were greater (P<0.05) for the crossbred lambs than for the purebred lambs. Slaughter body weight at 10-month age were not different brtween the tow groups  (P=0.08). Litter size was also increased by crossbreeding and using hormone (1.13 vs. 1.00), but lamb survivability was not different between the two groups. The fat yield decreased with crossbreeding. Crossbreeding increased (P<0.05) the weights of testis, liver, heart, and lung. It is concluded that crossbreeding Balouchi ewes with Romanov semen resulted in improved litter size, weaning and slaughter body weights, average daily gains from birth until weaning and slaughter, and carcass characteristics without affecting lamb survivability. Therefore, crossbreeding can be a profitable strategy to increase lamb (meat) production in Balouchi sheep.

Quality of wool has a major impact on its consumption and ultimate use and therefore, evaluation and genetic analysis of wool characteristics is one of the most important research fields for native sheep. Considering that Iran-black sheep is a result of Baluchi and Chios crossbreeding, the present study was conducted to compare and genetic analysis of fleece characteristics of Baluchi and Iran-black sheep.

In this study, wool samples were collected from 176 Baluchi and 105 Iran-black sheep in Abbas-Abad sheep breeding center located near to Mashhad, Khorasan-Razavi province, in October 2017. Fleece characteristics, including greasy fleece weight, average fiber diameter, average staple length, hetero-type fibers (%), modulated fibers (%), and true wool fibers (%) were measured. To determine the fixed effects (breed, year of birth, type of birth and sex) affecting wool characteristics of the breeds, the GLM procedure of SAS software was used. Least square means comparisons of different fixed effects subclasses was carried out by Tukey-Kramer test at 5 percent probability levels. The components of (co) variances and genetic parameters of the studied traits were estimated using the multi-trait animal model and restricted maximum likelihood using WOMBAT software.

Results showed that the differences between the breeds were significant for average fiber diameter, hetero-type fiber percentage and true wool percentage. None of the studied traits were affected by sex of lamb except for hetero-type and true fiber percentages (P<0.05). Year and type of birth could only affect the greasy fleece weigh (P<0.05). Coefficient of variation for greasy fleece weigh (26.28 percent), hetero-type fiber (76.77 percent) and modulated fiber (99.59 percent) showed that considerable variations are there for these traits in the two studied breeds. Average fiber diameter in Baluchi (26.28 micron) was significantly lower than Iran-black breed (29.26 micron) (P<0.05). True wool percent in Baluchi (94.81 percent) was significantly higher than Iran-black breed (92.65 percent) (P<0.05). Heritability of wool traits in Baluchi breed ranged from 0.26 (modulated fiber percent) to 0.45 (hetero-type percent) and in Iran-black breed ranged from 0.28 (modulated fiber percent) to 0.34 (true fiber percent).

In general, Baluchi breed had finer wool than Iran-black and Iran-black fleece characteristics were worse than the native Baluchi parent. Moreover, moderate heritability for the studied traits in both of the breeds indicated that selection programs for improving these traits in these populations would be effective.Keywords: Baluchi Sheep, Crossbreeding, Wool, Genetic parameters

Crossbreeding of fat-tailed native sheep with well known high performance thin-tailed sheep is currently widely used as a rapid solution to enhance production and reproduction, and reduction of fat-tail of native sheep. Nevertheless, comparison studies about native and crossbred animal performance in different environment is necessary for sheep husbandry industry.

This study was performed in the summer using 20 Lori-Bakhtiari (Lori) and 20 Lori-Bakhtiari×Romanov (F1) (Cross) sheep with an average weight of 31.6±2.5 kg in eight treatment with five-repetition for each in a completely randomized design with 2×2×2 factorial array including breed (Lori and Cross), water (free water and water restriction), and food (free food and food restriction). Unrestricted animals had free access to water and food, while water-restricted animals had free access to water for only one hour a day, and food-restricted animals were fed only with 0.45 to 0.65 percent of their body weight. After six weeks of treatments, lambs slaughtered and carcass traits were measured.

Food restriction has widely affected the measured traits in comparsion to water and breed and significantly reduced rectal temperature, respiratory rate, water intake, final weight, carcass weight, Carcass cuts and internal organ weight, fat-tail, visceral fat, total body fat, testis weight and volume (p≤0.01), while increased the water-to-feed ratio and carcass yield without fat-tail (p≤0.007). Water restriction had lesser effects and caused a significant increase in the difference between the maximum and minimum rectal temperature in each period (p<0.05), and decrease in water consumption (p=0.0001), but had no effect on other functional, physiological, and carcass traits. Crossbreeding also significantly reduced fat-tail and total carcass (p˂0.0001), and increased visceral fat, carcass yield without fat-tail, the proportion of carcass cuts, and testis weight and volume (p≤0.01), but had no effect on other traits.

In general, in normal food conditions (regardless the type of access to water) crossbreed animals performed better than Lori, but there is no differencess between them in severe food restriction. Therefore, it could be concluded that in all conditions F1 generation could make the carcass healthier and reduce the generation interval due to less carcass fat and faster maturation.

The aim of the present study was to investigate the performance of the hybrids obtained by crosses of the six Japanese silkworm lines named IRA1, IRA3, IRA5, IRA7, IRA9, and IRA11 and six Chinese silkworm lines named IRA2, IRA4, IRA6, IRA8, IRA10, and IRA12. The new hybrids derived from these lines along with available commercial hybrids (as control groups) for six traits including cocoon weight, cocoon shell weight, cocoon shell percentage, best cocoon weight, pupation rate and best cocoon pupation rate were measured and recorded in spring 2020. The IRA7×IRA6 and IRA7×IRA12 hybrids had more performance in comparison with commercial hybrids in terms of productive traits including cocoon weight and cocoon shell weight (P < 0.01), but, when productive and viability traits (pupation rate and best cocoon pupation rate) were considered together in an evaluation index, they were not among the selected hybrids. Commercial 31×32 hybrid in terms of cocoon shell weight and cocoon shell percentage had more performance in comparison with the other hybrids (new and commercial) (p<0.01). Hybrids had a significant difference for pupation rate and best cocoon pupation rate (P < 0.01), and the IRA5×RA12, IRA1×IRA10 and IRA11×IRA6 hybrids showed the lowest mean for both traits in comparison to other hybrids (P < 0.01). The results obtained from the present study indicated that seven hybrids including IRA9×IRA2, IRA11×IRA2, IRA3×IRA6, IRA3×IRA2, IRA7×IRA4, IRA7×IRA10 and IRA7×IRA8 were greater than the minimum set for every six traits. Therefore, they can be used to supply the country's required silkworm eggs.

Crossbred lactating cows were hypothesized to outperform Holsteins under environmental stresses . The objective of this study was , therefore, to compare production, reproduction, metabolism and health of purebred Holstein cows vs . crossbred Holstein × Montbeliarde and Holstein×Simmental cows under hot and humid conditions of north of Iran ( Sari , Mazandaran ) .

Dairy crosses were produced by crossing Holstein ( H ) cows with Montbeliarde ( M ) and Simmental ( S ) bulls’ semen . The performance and health of 70 primiparous cows from each breed ( 210 cows in total) were compared during their first lactation . Blood samples were taken from 15 primiparous cows from each breed at stages of close-up , calving , 21 days after calving. Samples were analyzed for glucose , BHBA, NEFA, calcium and mangium . Statistical analyses were performed using SAS programs ( GLM and MIXED procedures ).

Results showed that Montbeliarde × Holstein and Simmental×Holstein crossbred cows were not different (P> 0.05) from pure Holsteins in rectal temperature , fertility and other reproductive indices , 305-d milk yield, milk fat and protein yield, stillbirth, mastitis, and laminitis rates and close-up blood metabolites. However , Montbeliarde × Holstein cows had greater calving difficulty than did Simmental×Holstein cows (P < 0.05 ) . Also , both crossbred groups had higher incidence of metritis compared to purebred Holstein cows ( P < 0.05 ) . The purebred Holsteins exhibited more desirable udder traits than did crossbred cows (P < 0.05). The crossbred cows had more body condition score ( BCS ) during the transition period than did the pure Holsteins (p < 0.05 ). However, stature of Simmental × Holstein crossbred cows was shorter than pure Holstein . Foot angle was steeper for Holstein×Simmental and Holstein × Montbeliarde crossbred cows , but Holstein × Montbeliarde crossbred cows were similar to pure Holstein cows for hoof measurements .

findings of this study suggest that Holstein×Simmental and Holstein × Montbeliarde crossbred cows did not outperform first - lactation purebred Holstein cows, and that they experienced higher rates of dystocia and metritis under stressful hot and humid conditions .

The aim of this study was to evaluate the effect of crossbreeding on growth performance and carcass composition of purebred and crossbred Kurdilambs. Thus, two genetic groups including purebred Kurdi lambs (KK) and crossbred Kurdi*Romanov lambs (KR) were used. For analysis of carcasstraits, six lambs from each group were selected and slaughtered. The number of weaned lambs for KK and KR were 95 and 45, respectively. Ourresults indicated thatKK purebred lambs had the highest (4.5 kg) and KR crossbred lambs had the lowest (4.1 kg) birth weight (P < 0.05). CrossbredKurdi*Romanov lambs had higher average daily gain than KK purebred lambs (P < 0.05). The means of final weights of purebred lambs weresignificantly higher than crossbred lambs (54.8 vs. 41.5 kg, respectively). The genetic groups had no significant effect on cold and hot carcass weights.The effect of crossbreeding on fat thickness, fat-tail and leg was significant (P < 0.05). Crossbred lambs performed better than purebred lambs in thepre-weaning period, but purebred Kurdi lambs performed better than crossbred lambs in the fattening period. In general, it can be reported that thecrossbreeding of Kurdi sheep with Romanov sheep did not show the desireble results.

The aim of this study was to compare growth performance, carcass characteristics , and economic profits between Holstein -Belgian Blue cross and pure Holstein calves .

This study was carried out in the Mahdasht Milk and Meat farm , Dasht -e Naz Agriculture Company (Sari - Mazandaran ) , affiliated to Mostazafan Foundation of the Islamic Revolution , Iran . Beef crosses were produced by crossing Holstein (H) cows with Belgian Blue (BB ) bull’s semen . The performance of 25 calves of each breed ( 50 calves in total ) was compared in a fattening period of 7 months . Feed intake was measured daily for each group using a residual feed intake ( RFI ) system. Total Mixed Ration ( TMR ) diet was delivered to the animals at 8 o'clock in the morning and at 4 o'clock in the afternoon . Animals weighted monthly in order to obtain average daily gain. Statistical analyses were performed using SAS programs ( GLM and MIXED procedures ) .

The results indicated that average daily gain was significantly higher in Holstein - Belgian Blue cross calves than in pure Holstein calves (1.43 vs 1.33 kg ) . The pure Holstein calves had significantly lower dry matter intake than Belgian Blue crossbred . However, feed conversion ratio in the BB×H calves was remarkably more favorable than Holstein group (6.74 vs 7.04) . Dressing percentage for BB×H crossbred was higher than for pure Holstein . Effect of genetic groups on fat thickness through the front hindquarter, thickness of the fat covering over the back and thickness of the fat through the front hindquarter was not significant. Hovewer, thickness of the fat covering over the loin was significantly different among genetic groups (p < 0.05) . The comparisons of the least square means across genetic groups showed that smaller internal organs (e.g. liver) in Belgian Blue crossbred and largest in pure Holstein . Also, fat depots weight (subcutaneous and visceral) was significantly highest in pure Holstein and lowest in Belgian Blue crossbred (p < 0.05) .

Economic calculations demonstrated that the respective highest profit for the whole fattening period belonged to crossbred of BB×H (38543843 Rials ) , and pure Holsteins (24826300 Rials ) . Therefore, the hypothesis that the calves from Holstein - beef crosses have higher economic productivity than pure Holstein calves is confirmed .

The aim of this study was to compare feedlot performance, carcass characteristics, blood metabolites, and economic profits between pure andcrossbreeds Holstein calves. Crossbreeds were produced by crossing Holstein (H) cows with Angus (A), Charolais (C), Limousin (L) and INRA 95 (I)bull’s semen. The performance of 25 calves of each breed (125 calves in total) was compared in a fattening period of eleven months. The averagedaily gain was significantly higher in crossbred calves compared to pure Holstein calves. The interaction of breed and time was significant (P<0.01).The Charolais crossbred calves and pure Holstein had significantly lower dry matter intake than other crossbreeds, and feed conversion ratio in theC×H calves was remarkably more favorable than other groups (P<0.01). Dressing percentage and saleable meat yield for C×H, L×H and I×Hcrossbreeds were higher than for pure Holstein and A×H. Concentrations of plasma urea of Charolais crossbred calves was more than other groups(P<0.01). Economic calculations demonstrated that the respective highest profit for the whole fattening period belonged to crossbreeds of C×H, I×H,L×H, A×H, and pure Holsteins. In conclusion, the calves from Holstein-beef crosses had higher feedlot performance, dressing percentage andeconomic productivity than pure Holstein calves.

Crossbreeding is used in order to take advantage of the different and complementary strong points of two or more breeds and to utilize hybrid vigor. In this study the results of sheep crossbreeding have been reviewed from published over the last years in Iran. The results showed that much of the crossbreeding in the sheep industry in Iran due to incorrect selection of breeds was not suitable. The main disadvantages points of Iranian sheep are low reproduction performance, low longevity, insufficient growth rate, unsuitable carcasses composition and feed efficiency, respectively. While, in the most crossbreeding schemes have been done between Iranian breeds of sheep, focused on improve growth traits and reduced fat-tail weight, which created low and no significant changes in crossbreds for these traits, leading to reducing economical efficiency and unsustainable of rearing sheep in semi-intensive or village system over last years. Sustainability could been achieved by combining desirable characteristics from the indigenous breeds to keep fitness and marketability with those of specialist exotic breeds that had already demonstrated genetic potential for traits of economical importance for commercial production. However, research findings suggested that in well-planned efforts to create composite breeds (with minimum 50% native) using the prolific breeds (such as Romanov), with high mothering ability, low maturity age, suitable carcass composition and medium ewe body weight could increased productivity of sheep in village system in Iran.

This study was conducted to investigate the performance of growth and carcass traits of Lori-Bakhtiari (L), Romanov×Lori-Bakhtiari (F1RL), Pakistani×Lori-Bakhtiari (F1PL), (Pakistani×Lori-Bakhtiari)×(Romanov×Lori-Bakhtiari) (¼P¼R½L) and (Romanov×Lori-Bakhtiari)×(Romanov×Lori-Bakhtiari) (F2RL) crossbred lambs. Carcass characteristics of Lori-Bakhtiari (n=50), F1RL (n=41) and F2RL (n=20) crossbred lambs. Lambs were weaned at the age of 90 ± 5 days. Lambs were slaughtered at six month of age. Birth weight in Lori-Bakhtiari (5.12 kg) was significantly (P<0.05) higher than in Romanov (4.81 kg) and Pakistani (4.57 kg) crossbred. Weaning weight and body weight in six months were significantly higher (P<0.05) in Romanov × Lori-Bakhtiari crossbred lambs (30.96 and 42.75, respectively) than in Lori-Bakhtiari (28.81 and 41.69, respectively) and others genetic compositions. F1RL and F2RL crossbred lambs for lean percentage were significantly (P<0.05) higher than in Lori-Bakhtiari lambs in constant age (59.57, 60.57 and 50.03, repectively) and in constant weight (60.99, 59.24 and 49.56, repectively). Weight and percentage of total fat of carcass in Lori-Bakhtiari lambs (7.56 kg, 31.57% in constant age 6.65 kg, 30.46% in constant weight, repectively) were significantly (P<0.05) higher than of F1RL (4.25 kg, 20.91% and 4.30 kg, 20.08%, repectively) and F2RL (2.95 kg, 17.97% and 5.12 kg, 22.46%, repectively) lambs. In conclusion, crossbreeding between Romanov and Lori-Bakhtiari (F1) improves body weight at weaning and at six months of age, and carcass composition.

Prolactin is secreted from the anterior pituitary gland and plays an important role in the mammary gland development, differentiation and lactation. The aim of current study was to evaluate prolactin receptor gene polymorphisms in the Shal breed and Shal×Romanov crossbreeds. For this purpose, after blood sampling of animals and extraction of DNA using phenol chloroform method, two fragments of 176 and 215 base pairs from intron 1 of prolactin receptor gene were amplified using PCR reaction. Then PCR products were analysed by acrylamide gel electrophoresis and silver staining. Results showed that AB and AC genotypes were identified in 176 base pairs fragment of prolactin receptor gene (PRLP1) in Shal breed. The frequencies of these genotypes were 0.92 and 0.08, respectively; and the frequencies of A, B and C alleles were 0.5, 0.46 and 0.04, respectively. Also, in the position of PRLR1 of this gene in Shal×Romanov crossbreeds, the frequencies of AB and AC genotypes were 0.94 and 0.06, respectively; and the frequencies of A, B and C alleles were 0.50, 0.46 and 0.04, respectively. A polymorphism study in the 215 bp fragment of the prolactin receptor gene (PRLR2) in the Shal and Shal×Romanov crossbreeds showed only AA genotype. Results of this study showed that PRLP1 position in Shal breed and Shal×Romanov crossbreeds was polymorphic, however the PRLP2 position in the studied samples was monomorphic.

This study was conducted to compare the feedlot performance and growth traits of Lori-Bakhtiari (n=39), Romanov × Lori-Bakhtiari (n=38) and Pakistani × Lori-Bakhtiari crossbred (n=12) lambs during two consecutive years. Lambs were weaned at the age of 90 ± 5 days. After weaning and preliminary fattening period, three groups of lambs were fattened for 90 days in the same conditions. The results showed that weaning weight in Romanov × Lori-Bakhtiari crossbred lambs were significantly higher than in Lori-Bakhtiari and Pakistani × Lori-Bakhtiari crossbred lambs. Lori-Bakhtiari and Romanov × Lori-Bakhtiari lambs were not significantly different (P

Present experiment was conducted to compare the performance of Romanov×Lori Bakhtiari crossbred (F1) and Lori Bakhtiari male lambs. Fifteen lambs (initial body weight of 20±1 kg) from each group were fed ad libitum by a balanced diet, and weightd at the end of fattening period and at 15-days intervals. Average daily gain, daily feed intake, diet digestibility, rumen pH and ammonia nitrogen, blood glucose and urea nitrogen were determined. Chewing activity was studied during 24 h. At the end of fattening period, three lambs from each group were slaughtered, and the hot carcass and offal weights and were measured. Dry matter (58.79 vs. 62.35 %) and acid detergent fiber (35.84 vs. 39.92 %) digestibility in crossbred lambs were less than Lori-Bakhtiari sheep (P

Received: July 28, 2015 Accepted: July 12, 2017 1MSc Student, Department of Animal Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran 2Professor, Department of Animal Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran 3Professor, Department of Pathobiology, Faculty of Veterinary Medicine University of Tabriz, Tabriz, Iran *Corresponding author: [email protected]
Nowadays, beside of production traits, the characteristics of genetic resistance to diseases is considered as animal breeding aims in animal breeding. There is a growing interest by producers and consumers in the production of meat animals with minimal chemical input to reduce chemical residues in the meat and to increase the sustainability of livestock production. Selection of superior sires with identified resistance should be possible because parasite resistance that usually measured by fecal egg counts (FEC) or blood packed cell volume (PCV), is moderately heritable. One option to control helminth infections is to breed sheep that are resistant to these parasites. Genetic variation in response to parasite infection has been documented in the previous studies in some sheep breeds, mostly involving tropical and subtropical breeds, such as the Red Maasai, St. Croix, Florida Native, and Barbados Blackbelly. These breeds have consistently been more resistant to trichostrongyle infections than temperate breeds, such as Dorset and Rambouillet. The objective of this study was to evaluate differences between blood packed cell volume (PCV), parasitic nematode eggs per gram of feces (FEC) and FAMACHA scores of Ghezel breed and Ghezel-Baluchi crossbreds and determine that which group is more probable resistant to nematode parasites.
Material and Data were obtained from 24 one year-old lambs belonging to two genetic groups. Genetic groups including Ghezel (n= 12) and Ghezel-Baluchi (n=12) crossbreds. Ghezel × Baluchi group was containing 50% of Ghezel breed and 50% of Baluchi breed. Samples were collected at two different times on the 2012/2/19 and 2012/3/4 in the Khalat pooshan research station, Tabriz, East Azerbaijan. All lambs were born in the winter of 2011 and they were not given anthelmintic before and they were at the same environmental conditions. Fecal samples were collected directly from the rectum of animals and samples were tested by the method of Clayton Lane. The FEC were obtained for nematodes of Nematodirus (spp.), Marshallagia(spp.), Trichuris(spp.) and unknown nematode eggs. The other measured traits included body weight, PCV and Famacha test. All data except PCV were analyzed by the MIXED procedure of SAS software.Birth weight and blood packed cell volume were analyzed by the procedure of the GLM.
Results showed that the effect of the genetic group on nematodes eggs per gram of feces and Famacha test was significant (P The Ghezel-Baluchi crossbred ewes appeared to be more resistant to infection than the Ghezel breed in natural grazing condition. Crossbreeding of Ghezel and Baluchi sheep breeds increased resistance to internal parasites of the traits measured in this study. As a general conclusion, this research attempted to find resistance traits in relation to domestic parasites in the domestic environment. These characteristics have been investigated by veterinary parasitologists for many years, but animal breeders also need to consider the issue of improving the genetic resistance of sheep to nematodes, and more precisely how they measure the relevant traits and expressions to use in selection of breeder rams and ewes. It seems that crossbreeding of the Ghezel sheep breed with Baluchi breed increases the relative resistance to internal parasites in terms of Famacha, EPG and PCV as measured in this research. In the future there are two needed subjects in this area of animal science: a) to do more investigations to find exactly genetic explication for the relative superiority of crossbreds to pure breeds; and b) the discovery of the nature of the polygonal or non-additive nature of genetic resistance to nematodes in small ruminants.