فصلنامه تحقیقات تولیدات دامی
سال یکم شماره 2 (تابستان 1391)

More than 450000 Jabalbarez Red Goat are breeding in the cities of Jiroft and Kahnooj and produce cashmere, meat and dairy products. In this study which was carried out to analyse the polymorphism of GoLA-DRB3 gene in Jabalbarez Red goat using PCR-RELP, blood samples were randomly and individually taken from 100 goats. Then DNA was extracted from blood samples using DIAtom DNA prep Kit and its quantities and qualities were determined. Exon 2 of DRB 3.2 gene encompassing 285 bp amplified with heminested-PCR method in two rounds and PCR products were digested into fragments at 122bp and 163bp (T restriction pattern) or an undigested fragment at 285bp (t restriction patten). The Population was hardy-Weinberg equilibrium (p<0.05). Shanon Index, Nei index, observed heterozygosity and expected heterozygosity were calculated 0.69, 0.50, 0.52 and 0.50 respectively. Results show that the studied population has good genetic diversity, and the efficiency of GOLA-DRB3 marker for determination of genetic diversity is good. By using the results of this study and previous studies and the application of quantitative records and information for locus of this population, loci affecting quantitative traits can be detected.

In this research, fixed and random regression test day models were utilized for genetic evaluation of protein test day trait in Iranian Holsteins. The data set was consisted of 250,911 protein test day records belonging to 28,737 first lactation cows (three times a day milking) in 396 herds which calved between 1998 and 2008. The data were collected by Animal Breeding Centre of Iran. In fixed regression test day model, fixed effect of herd-recording year-production season-sperm type (HYSC), covariables of Holstein gene percentage, age at recording, days in milk (up to order 3), random effects of additive genetic and permanent environment were included. In the random regression test day model, HYSC, the covariables, and orthogonal Legendre polynomials (up to order 3) were included. Variance and covariance components were estimated using restricted maximum likelihood procedure. Additive genetic, permanent environment as well as phenotypic variances increased from the beginning towards the end of the lactation course. Heritability estimate obtained from fixed regression model was 0. 07 and the average heritability estimate obtained from random regression test day model was found to be 0. 104. Genetic trend for 305-d protein yield trait with random regression test day model 410. 64 g per year and with fixed test day model 124. 16 g per year was estimated. There was a significant difference between the models in terms of average predicted breeding value (P<0. 0001). For cows with records, Pearson and Spearman correlations between breeding values predicted by random regression model and fixed regression model were found to be 0. 926 and 0. 915, respectively.

To evaluate the effect of lactation stage on milk fat depression (MFD) a total of 938,047 test day records belonging to 108,077 first parity Iranian Holstein cows calving between 1995 and 2009 and distributed in 427 herds were used. Bassed on fat% to protein% ratio for each test day record, and the threshold point of -0.12, dependent variable was defined (codes 0 and 1 for the non- incidence and incidence of MFD, respectively). The data were analysed with a logistic generalized linear mixed model using GLIMMIX procedure of SAS software. In the model, fixed effects of stage of lactation, production season, sperm type used for dam insemination, age at first calving, animal type (grade or pure Holstein) and calving year, as well as random effect of sire were included. Mean probability of MFD increased from the beginning (0.1989) towards the middle (0.3192) of the lactation and afterwards it decreased. The maximum odds ratio (1.313) was obtained for MFD at the fifth month of lactation as compared to the last lactation month. With respect to the results, it could be therefore concluded that more economic return may be obtained through paying more attention to the nutrition regime of dairy cows.

Major histocompatibility complex (MHC) of vertebrates comprises a group of genes, which plays a central role in immune response and includes MHC- class I, II and III. The bovine MHC system is known as BoLA and its corresponding genes are located on chromosome 23. The BoLA-DRB3.2 genes are part of the MHC class II in cattle. These genes are highly polymorphic, found to be associated with resistance/susceptibility to infections and also with fertility, growth and milk production parameters. Polymorphism of exon 2 of the BoLA-DRB3 gene was detected by the PCR-RFLP method in 350 Iranian Holstein cattle. After DNA extraction, second exon of BOLA-DRB3 was amplified by the seminested PCR method. The fragments produced by amplifying second exon were cut by three enzymes, RsaI, PsuI and HaeIII. In restriction fragment analysis 18, 5 and 6 different allelic patterns were observed for RsaI, PsuI and HaeIII restriction enzymes, respectively. In total, 48 different alleles were detected where 9 out of 48 alleles were previously unreported. Allelic frequencies, genotype frequencies, expected and observed homozygosty and heterozygosity were calculated. The other step was evaluating the frequencies of alleles mediating resistance and susceptibility to Bovine leukosis(BLV), Foot and mouth disease (FMD), mastitis and somatic cell count (SCC), Cystic ovarian disease, some parasitic infections and increasing or decreasing milk production traits. The result of this study indicates that the exon 2 region of BoLA-DRB3 gene is highly polymorphic in the Iranian Holstein cattle. Also the high presence of alleles that are sensitive to BLV, mastitis, FMD and to some extent tick borne disease was a remarkable point. Alleles associated with susceptibility to BLV were most frequent. Frequency of alleles associated with milk production traits was similar to previous studied populations

This investigation was carried out in order to study the effect of replacing different levels of barley grain with dried citrus pulp in diet of Taleshy lambs during a 84-day feeding period. Twenty-four Taleshi male lambs were used in a completely randomized design with four treatments and six replications per treatment. Barely grain in control group (with 50% of barley grain) was replaced with three levels of dried citrus pulp (33, 66 and 100 percent). Dry matter degradability of dried citrus pulp in situ (5% outflow rate) was 67. 4%. Based on the results of this study, no significant differences for average daily weight gains (ADG) and feed conversion (FC) were found among the control, 33 % and 66% replacement. In treat with %100 replacement, however, ADG and FC were significantly lower and higher, respectively (P<0. 05). Urea concentration of blood plasma did not differ significantly among the dietary treatments (P>0. 05) but glucose concentration was significantly (60. 28 mg/dl) lower in treat with 100% replacement (P>0. 05). Based on the results of the present study it can be suggested that replacement of barley grain with dried citrus pulp up to 66% could be economically beneficial for growing lambs.

This study was carried out to evaluate the effects of different levels of dietary metabolizable energy and crude protein on performance (during 5-24 and 25-38 days of old) and carcass characteristics of Japanese quails. The experiment was conducted in a 3×5 factorial arrangement in a completely randomized design with four replicates at each treatment and 40 quails at each replicate. Fifteen diets including three levels of metabolizable energy (2800, 2900 and 3000 kcal ME/ kg) and five levels of crude protein (22, 23, 24, 25 and 26%) were considered. On day 41, one hundred twenty birds were slaughtered to access carcass characteristics. No significant interaction among energy-protein and protein levels on measured characters was observed. During 5-24 days of old, daily weight gain of quails fed 3000 kcal ME/ kg diet (4.42 g) was higher than the other levels (P< 0.01) and feed conversion ratio was lower in 3000 (2.90) than 2800 ME (kcal/kg of diet) (3.21) (P< 0.01). During 25-38 days of old, daily weight gain increased (6.16 g) and feed conversion ratio decreased (3.52) with increasing ME level from 2800 to 3000 kcal ME/ kg (P<0.05). The ME level had not significant affect on feed intake and carcass, breast and thigh yields. It concluded that using diets containing 3000 kcal ME/ kg and 22% crude protein is recommendable to achieve a desirable performance in Japanese quails.

Bovine growth hormone(bGH) gene, is a part of the multiple gene family that contains prolactin and placental lactogens. The variations in the introns of this gene, have potential usefulness as genetic markers and could help in the genetic improvement of populations. In ordre to investigate allele frequency of MspI in introne 3 of growth hormone gene of Guilan native cattle breed, blood samples were collected from seventy heads of randomaly choosen cattles (cows). Genomic DNA was extracted from these samples, using modified salting out method. Polymerase chain-reaction (PCR) procedure was used to amplify a 345 bp segment in this region and then digested with MspI restriction enzymes. Digested samples were run on the acrylamid gel 8% to recognize their genotype. This enzyme had two restriction sites and after digestion with MspI enzyme on that fragment and 2 allels and 3 genotypes have been observed. Frequency of MspI(+) allele was estimated to 0.4643. X2 test has showed the equilibrium of frequency MspI in samples.