مجله تولیدات دامی
سال پانزدهم شماره 2 (پاییز و زمستان 1392)

The objective of the present research was to apply logistic analysis for investigating some factors affecting incidence probability of milk fat depression (MFD) in early lactation of Iranian Holstein cows. The data set was comprised 80381 test day records (milk، fat and protein traits) belonging to 80254 first parity cows in 427 herds with calving year between 1995 and 2009. Based on fat to protein percentages for the first month of the lactation and also with respect to threshold point of -0. 12، dependent variable was defined as a dichotomous (zero code for lack of MFD and unit code for MFD) variable. A logistic mixed generalized linear model was fitted on the data using GLIMMIX procedure of SAS software. In the model، fixed effects of sperm type (local or exotic)، production season، first calving age، cow type (grade or pure Holstein) and random effect of animal’s sire were included. Cow type had no significant affect on MFD. Estimation of odds ratio for comparing different ages was found to be 1. 112 indicating that cows calving at lower age of 25 months are expected to show MFD by 11. 2 percent smore than the cows calving at the greater ages. The estimate of odds ratio for comparing of spring with summer، autumn and winter seasons were 0. 73، 0. 722 and 1. 182، respectively. The corresponding figures for summer as compared to autumn and winter seasons were 0. 987 and 1. 615، respectively، and autumn as compared to winter was found to be 1. 636. Daughters of the local bulls are expected to show MFD by 10. 8 percent more than that of the daughters of the foreign bulls.

The purpose of this study was to identify genomic regions of quantitative trait loci (QTL)، affecting carcass traits on chromosome 1 in an F2 population of Japanese quail. For this purpose، a three-generation resource population was developed by using two distinct Japanese quail strains، wild (meat type) and white (layer type). Eight pairs of white and wild birds were crossed reciprocally and 34 F1 birds were produced. The F1 birds were intercrossed to generate 422 F2 offspring. Phenotypic data including weight of carcass parts were collected on F2 birds. All of the animals from three generations (47 birds) were genotyped for eight microsatellite markers on chromosome 1. QTL analysis was performed with least squares interval mapping method fitting three various statistical models. Significant QTL were identified for breast weight، carcass weight، head weight and percentage of breast. There was also evidence for imprinted QTL affecting breast weight، a carcass part of high economic value، on chromosome 1. The proportion of the F2 phenotypic variation explained by the significant additive، dominance and imprinted QTL effects ranged from 1. 8 to 2. 3، 1. 2 to 3. 3 and 0. 5 to 2. 2 percent، respectively.

This study was conducted to detect polymorphism of gene BMP15، a member of Transforming Growth Factor β (TGFβ) family which has a crucial role in controlling the ovarian follicles development، ovulation rate and fertility. Samples were randomly selected from 91 Najdi goats in 3 geographical locations، northwest، southeast and center of Khuzestan province. After DNA extraction، amplification of 235 bp fragment of exon 2 of BMP15 gene was performed using specific primers. Sequence detection was executed after amplification of gene fragments. The association of BMP15 gene and litter size was done by SAS software. Results from sequencing were analyzed by Vector NTI software. The results identified three mutations in bases 529 (T to G)، 530 (C to G) and 576 (T to C). The largest litter size belongs to AA pattern. Point mutations in this gene will alter the Ovulation rate of the goat. Therefore، improving twining trait in Najdi population can be expected by marker assisted selection.

This research was conducted to evaluate the effect of different zinc (Zn) sources on performance، blood mineral and cell counts of Zandi lambs. 18 male lambs at weaning were supplemented with two different sources of zinc، 25 ppm ZnSO4 and 25 ppm zinc-peptide added to the basal diet as control. Live body weight، weight gain and feed efficiency improved with Zn-peptide supplementation (P 0. 05). Sera Zn concentration was higher and copper and iron concentration was lower in zinc supplemented groups (P<0. 05). Supplementation of zinc had no effect on blood cell counts except for white blood cells that decreased with zinc peptide supplementation (P<0. 05). It was concluded that adding 25 ppm zinc peptide to fattening lamb diet improved performance and cause to higher level of blood zinc.

This experiment was conducted to evaluate the effect of emulsifiers such as lecithin and bile salts on broilers performances fed diet containing vegetable fats. 192 male Ross broiler chickens were randomly allocated in a factorial experiment design of 3 × 2، consisting two sources of fat (four percent fatty acids or soy bean oil) and three emulsifiers (none، one percent lecithin and 0. 05 percent bile salts) in completely randomized design with four replicates and eight birds per each. Total weight gain and feed conversion ratio was not affected by fat sources while soya oil addition to diets increased feed intake (P<0. 05). Emulsifiers’ addition to diet improved weight gain feed conversion ratio (P 0. 05). The length and width of villi in jejunum، and crypt depths in duodenum were not affected by fat sources، while، crypt depth in jejunum and width of villi in ileum of birds fed on diets containing fatty acid were higher than other birds (P<0. 05). Addition of emulsifiers to diets increased dietary metabolisable energy (P<0. 05). In conclusion، addition lecithin or bile salts to diets containing soybean oil or its fatty acids، improved body weight gain and feed conversion ratio in broiler chicks by increasing in absorption area of intestine and dietary metabolisable energy.

In order to investigate the effect of different levels of silymarin (0، 100 and 200 mg/kg diet) on performance، carcass characteristics، blood parameters and antioxidant status، 120 day old chicks were assigned to 3 treatments with four replicates and 10 birds in each in a completely randomized design. Results showed supplementation of 200 mg silymarin significantly decreased the body weight gain (BWG) in starter (P<0. 05) and whole period of experiment (P<0. 01) and significantly increased feed conversion ratio at starter (P<0. 05)، grower (P<0. 05) and total rearing periods (P 0. 01). Also، addition of 100 mg silymarin significantly increased the carcass relative weight (P<0. 01) and supplementation of 200 mg silymarin significantly increased the breast relative weight (P<0. 05). Furthermore، 200 mg silymarin significantly increased the malondialdehyde and heterophil/ lymphocyte ratio and significantly decreased superoxide dismutase (P<0. 05). These results showed that supplementation of silymarin in diet under normal condition، improved the carcass and breast relative weight، but no had effect on bird’s oxidative status.

This experiment was conducted to investigate the effects of using different levels of thyme (Thymus vulgaris L.) medicinal plant and multi enzyme (Kemine) on performance and blood biochemical parameters of Japanese quails with 240 laying bird (6 up to 12 weeks) as a 2*2 factorial include two levels of thyme (0 and 0. 75 percent) and 2 levels of Kemine enzyme (0 and 0. 05 percent) in four treatments، 4 replicates and 15 laying quails in each replicate in a completely randomized design. Interaction between thyme and enzyme did not have any significant effects on egg production performance. Whereas egg weight in birds who consume thyme، was high (P<0. 05) and amounts of blood uric acid and eggshell thickness in birds who received enzyme and thyme in diets، increased (P<0. 05). The overall results indicated that using enzyme and thyme in Japanese quails diets can be have positive effects on egg weight and eggshell thickness.