IRANIAN JOURNAL OF APPLIED ANIMAL SCIENCE
Year:2018 | Volume:8 | Issue:1 |Papers Count:20

Both plant and animal ingredients are used commonly to formulate balanced diets for poultry. Although many changes have been occurred in the genetics, nutrition and feeding of modern meat chickens, free se-lection and indiscriminate uses of feedstuffs for the non-ruminant animal diets can be hazardous due to the emerging threat of diseases outbreak via animal by-products. Besides this, many other concerns of includ-ing animal ingredients in poultry diets such as high price, zoonotic effects, ban on uses, food safety and product quality etc., encourage the poultry integrators to use merely vegetable feedstuffs for diet formula-tion excluding animal by-products. Exclusive use of plant ingredients into poultry diets might offer poten-tial beneficial effects for optimizing poultry products. Poultry industry may be benefitted by using these cheap sources of vegetable ingredients for quality, safe and organic meat production. After all, most poultry integrators are looking for alternative ways to streamline production. This is why, currently the search for and the appropriate use of vegetable ingredients demand more research to explore their potential uses in poultry diets including other farm animals. However, despite the advantages of using vegetable feedstuffs in poultry diets, there are some associated problems that can affect the performance of meat chickens. So our current study is focused on to review these limitations of meat chickens fed vegetable-based diet, which include productivity, feed utilization and nutrient digestibility, leg bone health and litter quality of meat chickens.

In last decade, the uncontrolled use of antibiotics as growth promoter for livestock has led to the appearance of antibiotic-resistant pathogens and increased risk of infectious diseases. This situation has triggered intensive research efforts to find safe alternative strategies. Certainly, the plants and vegetables and their derivatives as natural safe substances could be good candidates in this respect. There is huge information on the immunostimulatory properties of herbal plans in human, and may contribute considerably to the improve-ment of the health and immune response and prevention of certain diseases in animals including poultry. Garlic (Allium sativum) is an herbal plant that has traditionally been used for the healing a number of human diseases and has in recent years been revealed to have immunostimulatory, anticardiovascular disease, antitumour, antioxidant and antimicrobial properties. The scientific evidences suggest that allicin and other active components of garlic have also some positive effects for livestock, including hypocholesterolemic, growth promoting, antimicrobial and antioxidant effects.

The aim of this study was to evaluate the effect of inclusion of tannic acid on some performance traits and nutrient digestibility in Holstein dairy calves. A total of 20 seven days old Holstein calves were randomly assigned to 4 experimental treatments with 5 calves each. The treatments were as follows: 1) basal diet formulated to meet all nutritional requirement of calves according to NRC (2001) and milk without any additive, 2) basal diet and milk supplemented with 4 mg tannic acid/L, 3) basal diet and milk supplemented with 6 mg tannic acid/L and 4) basal diet and milk supplemented with 12 mg tannic acid/L. The result showed that dietary inclusion of different levels of tannic acid improved feed intake, body weight gain and feed conversion ratio in treated calves. Dry and organic matter intake, and digestion of crude protein, natural detergent fiber and acid detergent fiber were improved in treated calves with tannic acid compared to the control group. The fecal consistency score showed that Inclusion of tannic acid resulted in improved fecal consistency from0 to 50 days of age (P≤0.05). In conclusion, tannic acid inclusion in milk could be benefi-cial for Holstein dairy calves with positive effects on their feed intake, body weight gain, feed conversion ratio and nutrient digestibility.

To determine the relationship between udder traits and peak milk yield, udder parameters of 203 Dehong crossbred dairy buffaloes were measured. The average peak milk yield (kg/day) of buffaloes was 9.60 ± 2.73, with average udder dimensions of 16.51 ± 10.05, 8.07 ± 3.26, 8.68 ± 3.92, 50.74 ± 8.82, 11.38 ± 3.08, 7.18 ± 2.18 and 7.73 ± 2.15 cm for udder depth, rear udder width, rear udder height, udder length, distance of fore teats, distance of rear teats, and distance of fore-rear teats, respectively. The peak milk yield was negatively correlated with udder depth (r=-0.28, P<0.01) and positively correlated with other mammary parameters (rear udder width, r=0.24, P<0.01; rear udder height r=0.32, P<0.01; udder length r=0.34, P<0.01; distance of rear udder r=0.20, P<0.01; distance of fore-rear teats r=0.40, P<0.01; left fore teat length r=0.25, P<0.01; left rear teat length r=0.29, P<0.01; right fore teat length r=0.22, P<0.01 and right rear teat length r=0.25, P<0.01). However, no significant correlation was found between peak milk yield and mammary vein and teat conformation. The results of the current study indicated that udder length has the greatest association with peak milk yield. Due to udder parameters fitting a normal distribution, it is valid to build evaluation procedures for the early selection of high yielding dairy buffaloes based on the experiences of Holstein cows scoring rules.

The objective of this study was to determine the chemical compounds of Iranian propolis (IP) extracts and to show flavonoids and phenol effects on methane production, fermentation characteristics and rumen mi-crobial population (in vitro). In this study two diets with different concentrate: forage ratios as (HC: high concentrate) and (MC: middle concentrate), respectively as non-supplemented or supplemented with differ-ent Iranian propolis (IP) extracts were used. The treatments were HC (control), HC+IP 25%, HC+IP 50%, HC+IP 75%, MC (control), MC+IP 25%, MC+IP 50% and MC+IP 75%, which means 25, 50 and 75 g of propolis in 100 mL ethanol 70%, respectively. The results showed that IP significantly in-creased gas production in IP 75% with different concentrate: forage ratios. Adding IP caused a decrease in pH, however this decrease was not significant in all treatments. There was a significant difference between the effect of HC+IP 50% on NH3-N compared to the HC+IP 25% and HC. Adding IP 75% significantly decreased CH4 production compared to the other treatments. In HC diet, there was no significant difference in total populations of protozoa and Ruminococcus albus between the individual IP 25%, 50%, 75% treat-ments, however when they were considered as the group, a significant difference was observed between them and the control group. The highest decrease and the highest increase in total populations of Prevotella bryantii was observed in IP 75% and in IP25%, respectively. In MC diet, methanogens were significantly reduced in IP 25%, 50% and 75%, compared to control treatment. The propolis extract caused improvement in fermentation and decreased methane and nitrogen ammonia. This may help the nitrogen retain longer in ruminants.

The accuracy of genomic breeding value prediction was investigated in various levels of reference population size, trait heritability and the number of quantitative trait locus (QTL). Five Bayesian methods, including Bayesian Ridge regression, BayesA, BayesB, BayesC and Bayesian LASSO, were used to estimate the marker effects for each of 27 scenarios resulted from combining three levels for heritability (0.1, 0.3 and 0.5), training population size (600, 1000 and 1600) and QTL numbers (50, 100 and 150). A finite locus model was used to simulate stochastically a historical population consisting 100 animals at first 100 generations. Through next 100 generations, the population size gradually increased to 1000 individuals. Then the animals in generations 201 and 202 having both known genotypic and phenotypic records were assigned as reference population, and individuals at generations 203 and 204 were considered as validation population. The genome comprised five chromosomes of 100 cM length and 500 single nucleotide polymorphism markers for each chromosome that distributed through the genome randomly. The QTLs and markers were bi-allelic. In this study, the heritability had great significant positive effect on the accuracy (P<0.001). By increasing the size of the reference population, the average genomic accuracy increased from 0.64±0.03 to 0.70 ± 0.04 (P<0.001). The accuracy responded to increasing number of QTLs non-linearly. The highest and lowest accuracies of Bayesian methods were 0.40 ± 0.04 and 0.84 ± 0.05, respectively. The results showed having the greatest amount of information (i.e. highest heritability, highest contribution of gene action in phenotypic variation and large reference population size), the highest accuracy (0.84) was obtained, with all investigated methods of estimation.

Genome-wide evaluation uses the associations of a large number of single nucleotide polymorphism (SNP) markers across the whole genome and then combines the statistical methods with genomic data to predict the genetic values. Genomic predictions relieson linkage disequilibrium (LD) between genetic markers and quantitative trait loci (QTL) in a population. Methods that use all markers simultaneously may therefore result in greater reliabilities of predictions of the total genetic merit, indicating that a larger proportion of the genetic variance is explained. This is hypothesized that the genome-wide methods deal differently with genetic architecture of quantitative traits and genome. The genomic nonlinear Bayesian variable selection methods (BayesA, BayesBand Bayesian LASSO) are compared using the stochastic simulation across three effective population sizes (Ne). Thereby, a genome with three chromosomes, 100 cM each was simulated. For each animal, a trait was simulated with heritability of 0.50, three different marker densities (1000, 2000 and 3000 markers) and number of the QTL was assumed to be either 100, 200 or 300. The data were simu-lated with two different QTL distributions which were uniform and gamma (α=1.66, β=0.4). Marker den-sity, number of the QTL and the QTL effect distributions affected the genomic estimated breeding value accuracy with different Ne (P<0.05). In comparison of three methods, the greatest genomic accuracy ob-tained by BayesB method for traits influenced by a low number of the QTL, high marker density, gamma QTL distribution and high Ne.

Over the last 40 years, evidence has accumulated to suggest the ubiquitous presence of infections with in-tracellular bacteria of the genus Chlamydia in different livestock species. Different methods to clinical specimens substantiated such widespread, but mostly clinically unapparent, presumably low-level infec-tions. In this initial epidemiological study, we addressed the question of chlamydial infection of conjunctiva and genital tract in apparently healthy sheep. In this research, 33 sheep and 20 goats which had previously been exposed to the possibility of sexual transmission of Chlamydia, examined by conjunctiva (53 swabs) and vaginal swab (53 swabs). After DNA extraction by boiling method, presence of Chlamydia pecorum was investigated by nested PCR. Chlamydia pecorum strain W73 was used as positive control. In this re-search, 10 infected swab samples (from 106 swab samples) contain of 7 vaginal (70%) and 3 conjunctival swabs (30%) were detected. All positive vaginal swabs and 3 positive conjunctival swabs were related to aborted and adult animals, respectively. According to higher percentage of Chlamydia pecorum infection in apparently healthy sheep, carrier state in sheep is more probable than goats. Vaginal secretion is more im-portant route of chlamydial infection dissemination towards conjunctival secretion. Because of high risk of chlamydial infection in cows, attention to role of sheep in disease epidemiology was recommended.

The data set used in this study contained 8793 records of lamb's weight (kg) from 320 sires and 2349 dams collected during 1989 to 2014 from the Lori-Bakhtiari flock at Shooli station in Shahrekord, Iran. Non-genetic factors and genetic parameters (partitioned into autosomal, sex-linked and maternal) of lamb's weight at different ages were estimated using without and with sex-linked genetic effects models. The results showed that the overall mean of lamb’s weight were 5.01, 28.93, 41.42, 51.33 and 56.52 kg at birth, weaning, 6, 9 and 12 months of age, respectively. The effect of fixed factors; year and month of birth, age of dam, sex of lamb, type of birth; dam body weight and age of lamb (days) as linear covariate were significant (P<0.01 or 0.05) on lamb's weight at different ages. The heritability estimates of lamb's weight obtained by most favorable model (without and with sex-linked genetic effects for pre and post-weaning weight, respectively) were low to medium and ranged from 0.08 to 0.22 for autosomal, 0.01 to 0.14 for sex-linked and 0.04 to 0.20 for maternal additive genetic effects. The estimates of autosomal, sex-linked and maternal genetic correlations of lamb's weight at different ages were medium to high. In conclusion, lamb's weight at different ages can be improved by farm management practices and improving environmental factors. Genetic analysis using linear models which able to estimate breeding values in autosomal, sex-linked and maternal separately, could make a more effective genetic selection to improve growth traits in lambs.

The present study aimed to estimate heritability, genetic and phenotypic correlations between body weight and body measurement traits in Iranian Makuei sheep. The used data were collected from 1989 to 2012 at Makuei Sheep Breeding Station in Maku (West Azarbayjan province). The data included body weight and five body measurement traits (body length (BL), heart girth (HG), withers height (WH), rump height (RH) and leg circumference (LC)) in 6, 12 and 18 months of age with 400, 900 and 350 records in different time, respectively. The data were analyzed using multi-trait animal model through DFREML software. Results showed that the estimated heritabilities for body weight and body measurement traits in 12 months of age is less than those for 6 and 18 months of age; those comes down from 6 to 12 months of age, then go up to 18 months of age. In six months of age the highest and lowest genetic correlations were between body weight (BW) with WH and LC; respectively, and the highest and lowest phenotypic correlations were between BW with RH and LC; respectively. Genetic and phenotypic correlations between body weight in six months of age and body measurement traits were approximately high but with leg circumference were low. Genetic correlations in 12 months of age were generally higher than phenotypic correlations. Genetic correlations between body weight in 18 months of age and body measurement traits were moderate to high and the highest genetic correlation was found between body weight in 18 months of age and body length. The positive correlation between body weight and body measurements in different ages indicated that selection for body measurements would results body weight improvement.

This experimental trial was conducted to study the effects of dried poultry dropping based diets on the dry matter intake, live weight changes, nutrient digestibility and N-balanceof Konkan Kanyal goats. Thirty Konkan Kanyal goats aged between 9-12 months and with average weight of 13.66 kg were used in a ran-domized block design (RBD) experiment. The experimental goats were randomly assigned to five treat-ments (TI-T5). T1 were goats fed with 0% dried poultry droppings based diets (DPDBD), T2 were fed with 20% dried poultry droppings based diets (DPDBD), T3 were fed with 40% dried poultry droppings based diets (DPDBD), T4 were fed with 60% dried poultry droppings based diets (DPDBD), T5 were fed with 80% dried poultry droppings based diets (DPDBD). Mean dry matter intake (kg) was higher in treatment groups supplemented with dried poultry droppings based diet T2, (572.99±18.12), T3, (614.09±27.76), T4, (605.37±32.79), T5 (619.24±9.15) in comparison to the control treatment group T1, (571.47±28.86). The final live body weight (kg) was significantly (P<0.05) higher in T5 (19.4±1.27) than T1 (14.72±1.02), T2 (15.45±0.88), T3 (16.03±0.48) and slightly higher than T4 (18.28±1.19). Similarly in feed conversion effi-ciency T5 (9.0±0.28) and (8.34±0.44) T4 performed significantly (P<0.05) better compared to other treat-ment groups: T3 (3.53±0.29), T2 (2.88±0.48) and T1 (2.89±0.34). Nutrient digestibility was significantly higher (P<0.05) in T5 in all parameters measured, N-balance was positive across the treatment groups with significant differences across the board. The results of this study suggests that feeding of dried poultry droppings based diets up to 80% inclusion to Konkan Kanyal goats consuming finger millet straw as basal diet would improve the feed value and give satisfactorily performance.

BMP15 and GDF9 are two oogenesis specific genes play a pivotal role in female fertility in mammals and potential for improvement of prolificacy in marker-assisted selection. The aim of present research was to investigate the variation and association between BMP15 and GDF9 polymorphism and litter size in Mark-hoz goats. The sequence variability of the different amplified fragments utilized for genotyping was further investigated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing. Sequencing technology allowed the detection of two nucleotide variations: A both non-functional mutation (G/A) transition at nt 1026 known as P3) and a synonymous mutation at 1049 position which for the first time was found at the BMP15 gene. Also, GDF9 gene exhibited a polymorphism on BcnI site (1159 bp) within exon 2 of amplified PCR products (glutamine/proline). Our analysis using general linear model (GLM) statistical methods showed litter size was significantly influenced by genotypes of GDF 9 (P<0.01). Heterozygous genotype showed higher litter size than homozygous genotypes (P<0.01). The conformation of this founding would need large sample size and test to screen in other indigenous goats.

The current trial was conducted to investigate effects of tryptophan (Trp) supplementation in crude protein (CP) deficient diets on performance, gut development and immune responses in broiler chickens. A total of 420 day-old broiler chicks (Ross 308) were assigned to one of 6 dietary treatments, comprising 5 replicates in a completely randomized design including: 1) control diet (CTL) (diet based on Ross 2014 recommendation), 2) CTL+0.15% Trp (+Trp), 3) low CP diet 1 (LCP1) (10% CP lower than Ross 2014 recommendation), 4) LCP1+0.15% Trp, 5) low CP diet 2 (LCP2) (20% lower CP than Ross 2014 recommendation), and 6) LCP2+0.15% Trp. Body weight (BW), daily feed intake and feed conversion ratios were evaluated in different phases of the experiment. Digestive organs were measured on day 28 and at the end of the rearing period. Morphology of small intestine was evaluated on day 28 of age. The tonic immobility test was applied at the end of the experiment. Birds receiving low CP diets had lower BW and daily weight gain (DWG) during the starter period (P<0.05). Supplementation of Trp to LCP1 diets ameliorated reduced growth performance (P<0.05), with no effect when added to LCP2 diets. Abdominal fat deposition tended to be lower in birds consuming+Trp diets. Chickens fed on LCP2 had increased crypt depth and lower villus height to crypt depth ratio than birds in CTL group in jejunum and ileum (P<0.05). Feeding LCP2 and LCP2+Trp diets increased heterophil to lymphocyte ratio (H/L) in broiler chicks while had no effect on tonic immobility duration. In conclusion, Trp. supplementation to LCP1 diets could ameliorate the loss of performance in broilers received low CP diets.

The effect of grape seed extract (GSE) feed supplementation on performance, antioxidant enzyme activity, and immune responses in broiler chickens suffering from heat stress were investigated in this study. Ex-perimental diets including control diet (with no additive), 3 levels of GSE (150, 300, 450 mg/kg), and one level of vitamin C (300 mg/kg) as a positive control were fed to the birds from 1 to 42 d of age. The chronic heat stress (34±1oC temperature for 5 hours per day) was provided from 29 to 42 d of age. The GSE sup-plementation up to 300 mg/kg diet increased the average daily gain of broiler chickens compared to the control group prior to heat stress (1-28 d). During the heat stress condition, dietary GSE at the rate of 300 and 450 mg/kg diet improved feed conversion ratio. The GSE supplementation at 300 mg/kg diet increased IgG titer as a primary and secondary response to sheep red blood cell (SRBC) injection. In addition, birds fed diet with GSE (150, 300, 450 mg/kg diet), or vitamin C (300 mg/kg diet) had higher levels of IgG titers as a secondary responses to SRBC. The GSE supplementation at the rate of 300 and 450 mg/kg diet reduced heterophil percent, heterophil/lymphocyte ratio, and increased the percentage of lymphocyte of broilers under heat stress. Supplementation of diet with GSE (300, 450 mg/kg diet) increased glutathione peroxidase (GPx) activity in birds under heat stress condition. The GSE or vitamin C supplementation did not affect the results of cutaneous basophil hypersensitivity (CBH) response, and relative weights of spleen and bursa of fabricius in chickens under heat stress. However, supplementation of diet with GSE (300, 450 mg/kg diet) or vitamin C (300 mg/kg diet) increased relative weight of thymus in birds under heat stress condition. Thus, GSE supplementation could alleviate the detrimental effects of heat stress in broiler chickens better than vitamin C and it is preferable for the health and economic goals since it is a natural waste by-product.

An experiment was conducted to evaluate the effects of different levels of licorice powder (LP) in diet on performance, egg traits and some serum biochemical parameters of laying hens in the late laying period. Totally 180 Hy-Line W-36 layer hens aged 55-68 weeks with similar weight were selected and assigned to 5 treatments, 3 replicates and 12 hens in each replicate in a completely randomized design. Experimental groups included 1) basal diet (without LP), 2, 3, 4 and 5) basal diet supplemented with 0.5, 1.0, 1.5 and 2.0% of LP, respectively. The results showed that the use of different levels of LP significantly affected the performance and egg traits of laying hens (P<0.01). The highest performance for egg production (60.96%), egg weight (61.50 g), egg mass (37.60 g) and the best feed conversion ratio (2.93) was achieved with 2% LP treatment. The amount of daily feed intake was not affected by dietary treatments. The highest amounts of yolk weight (29.43%), egg shell thickness (0.366 mm), haugh unit (74.79) and yolk color index (4.78) were obtained using 2% LP diet. Licorice powder supplementation in the diets of hens did not significantly alter the serum blood parameters compared to the control (P>0.05). It can be concluded that in laying hens in late laying period, using 2.0% of Licorice powder, without having any significant effects on serum bio-chemical parameters, can improve their performance and egg traits.

This experiment was carried out to determine the effects of turmeric, cinnamon, ginger and garlic powder on mixed sex Cobb-500 broilers performance, serum antioxidant status, and serum thyroid hormones. Heat stresses were created by increasing ambient temperature to 32-34 °C from 12: a.m. to 16: p.m. during days 31-42 of the experiment. Blood serum samples were obtained from 6 broilers of each treatment at the end of experiment (day 42) to assess antioxidative activities of liver enzymes and thyroid hormones. Chicks fed diets supplemented with medical plants tended to have higher average daily gain and had greater spleen weight compared to the control. Supplementation of medical plants increased activities of total superoxide dismutase (SOD) in cinnamon, glutathione peroxidase (GPX) in ginger, catalase (CAT) in cinnamon and garlic powder, total antioxidant capacity (TAC) in cinnamon, alkaline phosphatase (ALP) in garlic powder and corticosteroid (CE) in cinnamon groups. But, the supplementation reduced concentrations of malondial-dehyde (MDA) in cinnamon group (P<0.05). Concentration of thyroid hormones (THs) in medical plant-supplemented broiler chicks tended to be higher at 42 d of age compared to the control (P<0.05). Supple-mentation of turmeric and ginger caused significant reduction in feed conversion ratio (FCR), improvement in performance, and enhancement in antioxidant enzyme activity with the increase in cinnamon consumption. Also, turmeric and ginger increased THs of broilers.

This study was carried out to determine the nutritional value of different chickpea varieties using in vitro gas production technique. As a result, significant variations in terms of chemical composition, gas production rate and metabolizable energy, net lactation energy and digestible organic matter were found among the 8 different chickpea varieties. The crude protein contents of chickpea varieties ranged from 15.26 to 18.52% DM; the crude fat contents of chickpea varieties ranged from 4.14 to 5.33% DM; ash content of c hickpea seeds varied from 2.69 to 3.46% DM. The neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents of c hickpea varieties varied from 12.46 to 17.29% DM and 3.80 to 4.87% DM, respectively.24 h total in vitro gas production of varieties ranged from 58.67 to 81.66 mL/200 mg dry matter (DM). The calculated metabolizable energy (ME) and digestible organic matter (DOM) contents of c hick-pea varieties ranged from 10.25 to 13.83 MJ/kg DM and 68.69 to 91.64%, respectively. In conclusion, chickpea can be used successfully for ruminant feeding and also Çağatay and Izmir 92 varieties are better than the other varieties studied according to their nutritive values.

The response of laying Japanese quails to dietary levels of energy and protein on performance, egg quality, hatchability, fertility and their effect on subsequent offspring live body weight was investigated. A total of 432 Japanese quails (13 weeks old) were divided into nine treatments. Each treatment comprised of four replicates of twelve birds (9 females and 3 males). Nine diets including three levels of metabolizable energy (ME) (11.51, 12.41 and 12.77 MJ/kg diet) and three levels of crude protein (CP) (180, 200 and 220 g/kg diet) in a 3 × 3 factorial design were formulated. Weight gain and egg production were higher in quails fed diets with high level of ME (12.77 MJ/kg diet) and CP (220 g/kg diet). Feed conversion ratio (FCR) improved linearly with the increase in dietary energy level, and the best FCR was obtained by 12.77 MJ ME/kg diet (P<0.05). Increasing energy and protein levels resulted in an increase in egg shell thickness, egg shell strength, albumen and yolk indexes (P<0.01). Percentage of hatchability and subsequent offspring live body weight at hatch were significantly affected by dietary ME and CP levels (P<0.01). Offspring live body weight were higher in chicks from hens fed diets high in energy and protein level. Based on the results of the present study, ME and CP levels of laying Japanese quails diets had significant effects on performance, egg quality and offspring live body weight at hatch.

Growth hormone gene plays a critical role in regulating growth and metabolism which leads to potential correlations between the polymorphisms of this gene and economic trait. A 776 bp fragment within the intron 1 region of the growth hormone gene from 346 individuals of an F2 population of Japanese quail was amplified. The polymerase chain reaction (PCR) product was digested using MspI restriction enzyme. restriction fragment length polymorphisms (RFLP) analysis revealed three restriction sites, which led to four different restriction fragments. Four distinctive alleles (A, B, C, and D) and four different genotypes (AA, AB, AC, and AD) were identified in this population. The results indicated that the population deviated from the Hardy-Weinberg equilibrium (P<0.005). The observed heterozygosity and Shannon's information indexes were 0.720 and 0.560, respectively, which demonstrated high diversity in this population. There was a significant association between RFLP patterns and live weight at four and five weeks of age, carcass weight, breast weight and proportion of the internal organs. Carcass weight of the AB birds was less than that of other genotypes (P<0.05). These results suggested that growth hormone gene can be used as a candidate gene for marker-assisted selection to improve performance in Japanese quails.

The current study was conducted to consider how pedigree and the gene-dropping analysis can use to monitor genetic diversity, and to recommend a breeding strategy for improving breast weight (BRW) in a population of Japanese quail. A total of 312 birds were divided equally into two lines. One line (S1) was selected for four-week body weight (BW) based on breeding value, and the other (S2) was selected for four-week BRW based on between-family selection. The distributions of allele frequencies originating from the founders were estimated using gene-dropping simulation software for the actual pedigree of each line. The results revealed that the total net genetic improvements in BW and BRW in the S1 and S2 lines were 28.3 and 9.7 g vs.23.3 and 6.8 g, respectively. The average numbers of surviving alleles in the descendants were 59.6 and 31.2 for the S1 and S2 lines, respectively, which were 19.1% and 10% of the total number of as-signed alleles in the base population. It can be concluded that for stabilizing the response to selection for improving BRW, it is recommended to use indirect selection of BW based on breeding values. The results obtained from the gene-dropping experiment showed that the between-family selection method results neither in more genetic gain nor in greater remaining genetic variation.