مجله علوم دامی ایران
سال چهل و پنجم شماره 3 (پاییز 1393)

The increase of reproduction performance is one of the critical factors for improving economic achievement and sustaining small and middle scale livestock producing. For this to happen، participatory research and extension programs should be implemented with the help of livestock producers. In the present study، the knowledge and attitudes of target livestock producers of ewe estrous synchronization model plan in Markazi (N=11) and Fars (N=12) provinces were investigated. The data were collected using questionnaires and in-depth interviews. The results indicated that producers obtained an average score in the knowledge test. The respondents’ attitudes towards the technology were positive. The main factors preventing the technology to be extended among neighbourhood livestock producers included: lack of attention to some of the advices (e. g.، small number of rams when mating، and inappropriate feeding)، not providing educational programs by organizers، lack of appropriate indicators to choose target producers، and lack of a complementary and tuned relations between educational programs and practice.

In a completely randomized design، the effect of four iso-protein and iso-caloric diets containing different levels (0، 8، 16 and 24%) of processed broiler litter was studied on the fattening performance of 60 Holstein male calves (with initial weight of 309±9kg and about 8-9 month age) for a period of 200 days. At the end of the experiment، all animals were slaughtered and then the carcasses، edible and non-edible parts were weighted after carcass inspection. Results showed that the average dry matter intake of calves fed diets containing four levels of poultry litter، were respectively 10. 17، 10. 28، 9. 97 and 10. 26 kg/d، daily weight gain were 1339، 1305، 1362 and 1311 g/d، and feed conversion ratio were 7. 7، 7. 9، 7. 4 and 7. 6 that were not affected by the experimental diets (P>0. 05). In addition، the carcass weight، carcass dressing percentage and organs were not different among the treatments (P>0. 05). Based on the visual tests، the carcasses and organs، no differences were observed between the animals received different levels of broiler litter. Economically، feeding cost was lower when the animals received diets containing 16 and 24% of broiler litter. Based on the results of this experiment، the processed broiler litter could be included in the diet of finishing calves، however it is recommended that the optimum level to be about 20% on the farm conditions.

In this study 36 Holstein bulls (initial BW of 345±61 kg) were randomly assigned to 6 dietary treatments، following a 3×2 factorial arrangement، with 3 concentrate level of fish oil (0، 1 and 2. 1% of DM) and 2 levels of alfalfa hay versus corn silage (10 and 20 % of alfalfa hay forage) to investigate the effects of fish oil supplementation and ratio of alfalfa hay and corn silage in diet on performance، carcass characteristics and fatty acids profile. There was no difference in average daily gain، dry matter intake and feed conversion ratio among dietary treatments. The highest level of fish oil had a negative effect on dry matter intake (P<0. 01) regardless of alfalfa hay level. In addition، high portion of alfalfa hay forage in diet affected DMI detrimentally، regardless of fish oil levels (P<0. 01). Fish oil supplementation increased TBARS value at 2 months of storage (P<0. 01). Moreover dietary inclusion of fish oil increased the concentration of Eicosapentaenoic and docosahexaenoic (P<0. 01) fatty acids (P<0. 01) which subsequently reduced n-6: n-3 (P<0. 01). The results of this study indicate that fish oil can be supplemented to feedlot diet to enrich ruminant products by introducing some peroxides production inhibitors in storage period. Furthermore، alfalfa hay can be replaced by corn silage to mitigate the detrimental effect of supplemented fat on dry matter intake.

The objective of the present study was to investigate the effects of high dietary levels of L-arginine during starter period on growth، intestine morphology and immune system of female Ross broiler chicks. In this experiment، 192 day old female Ross broiler chicks were fed with 4 dietary treatments in a completely randomized design، in which each dietary treatment included 4 replications. Dietary treatments included 100%، 153%، 168% and 183% of digestible arginine، based on the Ross recommendation، and were fed from day 1 to 10. On d 10 of the experiment، chicks were weighed and feed consumption was recorded. Then، three chicks per replication were slaughtered in order to survey intestinal histology and immune system. The results showed that high dietary levels of arginine had an increasing effect (P<0. 01) on 10th day body weight، feed efficiency، immune system characteristics، weight and length of small intestine، and its villus height and crypt depth. According to the results of this study، 168% digestible arginine، based on the Ross recommendation، had the best desirable results on growth improvement of broiler chicks and it also improved weight، length and histology of small intestine، and immune characteristics.

The objective of this study was to investigate the effects of different levels of amino acid and feeding methods on performance and immune system of broiler chickens. Experimental design was based on completely randomized design in a factorial arrangement with 3 feeding methods [control (ad libitum feed intake)، intermittent feeding (IF) and continuous feed withdrawal (FW))، and 2 amino acid levels (level recommended by Arian and 8 % more). Each treatment was replicated 6 times with 23 male broilers per replicate. The CFW method was associated with a decreased mortality rate (P<0. 05). The IF and FW methods improved feed conversion ratio (P<0. 05). In CFW and IF feeding programs، the relative weight of spleen was increased (P<0. 05). At higher amino acid level، the percentage of circulatory lymphocyte was decreased and that of heterophil and heterophil to lymphocyte ratio were increased (P<0. 05). In conclusion، it seems that the FW feeding regimen with Arian recommended amino acid level might have a positive effect on the cellular but not the humeral immune system with no adverse effect on growth performance.

The aim of this experiment was evaluating effect of fish oil versus palm oil on mammary gland health and milk production in Holstein cows. Ten multiparous Holstein cows were used from six week before up to 63 days after parturition. Feed intake and milk production were recorded daily، milk composition، body weight and body condition score were measured weekly and blood metabolites were determined 21 day intervals. Milk production with fish oil consumption was increased from 6th weeks of lactation (P<0. 05). Among milk composition، only percentage and yield of milk fat were decreased in FO group (P<0. 05). Milk somatic cell count (P=0. 06) and score (P<0. 05) were decreased with fish oil consumption. Among blood metabolites، serum total cholesterol، LDL-cholesterol and LDL to HDL-cholesterol ratio were decreased in FO group (P<0. 05). Results indicated that consumption of fish oil in transition period besides conserving milk production can alleviate undesirable effects of negative energy balance in early lactation، and decrease milk somatic cell count.

The effects of ensiling Alhagi with waste date Palm on rumen parameters and microbial protein synthesis in Kermani sheep were investigated. 100 kg Alhagi with 20 kg waste date Palm were mixed and ensiled for 45 d. The experimental diets containing 0، 7، 14 and 21% Alhagi with waste date Palm silage. Four male kermani rams were used in change over design with four 21-days period. Ensiling alhagi with waste date Palm increased crude protein and fat percentages (P<0. 05). Apparent digestibility of crude protein was decresed by increasing the level of ensiled alhagi with waste date Palm (P<0. 05). The amounts of nitrogen intake، digested nitrogen and retained nitrogen in sheep fed 21% of ensiled alhagi with waste date Palm were higher (P<0. 05). Eexcretion of allantoin، purine derivatives and microbial protein synthesis were increased linearly in response to increasing level of ensiled alhagi with waste date Palm. Total protozoa population and Entodinium species per ml rumen liquid changed quadratically (P<0. 05). In conclusion، due to nitrogen balance improvement and increased microbial protein in diet containing 21% ensiled alhagi with waste date palm; it can be fed to animals without any negative effect on their performance.

In this study، the number of 1802 longevity records of ewes collected during 1989 to 2010 in Breeding Station of Lori-Bakhtiari sheep flocks were used to estimate of genetic، environmental and phenotypic trends for economic lifetime. The breeding values of a ewe’s lifetime were estimated by restricted maximum likelihood procedure under an animal model of univariate analysis. The best linear unbiased prediction of breeding values estimated and genetic trends were estimated as a regression coefficient of average breeding values on the birth year of ewes. The environmental and phenotypic trends estimated as a regression coefficient of average environmental deviation and phenotypic deviation (deviations of phenotypic values from overall mean) on the birth year of ewes. The results showed that، genetic trend of longevity was positive (0. 033 days) but insignificant from zero. While the environmental and phenotypic trends were equal to -27. 81 and -27. 78 days، respectively، and significantly different from zero (P<0. 05). Thus، selection for growth traits did not affect longevity traits as genetically and to exhibit negative phenotypic trend for longevity the environmental factors should improve firstly

Insulin-Like Growth Factor-I (IGF-1) is a peptide hormone which is similar in molecular structure to insulin and it is located on chromosome 5 in cattle. Since the IGF-1 plays an important role in the growth and development of multiple tissues، the purpose of current study was to identify the IGF-1 gene polymorphism in Sistani beef cattle. A total of 53 Sistani beef cattle (one year) were randomly selected and blood samples were drawn from the cervical vein. DNA was extracted from the whole blood with modified salting-out method. A 249 bp length fragment in exon 1 of IGF-1 gene was amplified by polymorphism chain reaction by using specific primer pairs. Genotyping of each sample was performed by using restriction enzyme SnaBI and electrophoresed on 2% agarose gel. The results revealed the existence of two alleles A and B for the examined locus with the frequencies of 0. 25 and 0. 75، respectively. Three different genotypic variants including AA، AB and BB were identified with genotypic frequencies of 0. 057، 0. 396 and 0. 547، respectively. Chi square test based on observed and expected frequencies of different genotypic variants of the exon 1 of IGF-1 gene in Sistani cattle population showed that deviation from Hardy-Weinberg equilibrium was not significant. Analysis associate of the studied genotypes and growth related traits showed significant effects between AA and AB genotypes (P<0. 05). On the basis of obtained results it was revealed that the IGF-1 gene can be used as a candidate gene for growth related traits in Sistani population.

Experiment was conducted to evaluate the effect of L-glutamine on coated sperm freezing by using four rams. Semen was collected by artificial vagina contact with a tube containing Tris-fructose-egg yolk 15%. Samples were pooled and centrifuged. After removing supernatant and diluting pellet، samples were split into 5 equal part and added 0، 40، 80، 120 and 160 mM L-glutamine. Samples were frozen by using liquid nitrogen After two weeks، samples were thawed and incubated at 37 °C for nine h. Sperm motility، plasma membrane integrity، viability (Hoechst 33258) and acrosome reaction (PNA-Alexa -flur-488) were investigated at 0، 3، 6 and 9 h. The main effect of L-Glutamine showed that sperm viability was higher in 0 (35. 95%)، 40 (40. 65%) and 80 (45. 95%) mM L-Glutamine than 160 mM L-Glutamine (30. 40%; P<0. 05). There was an interaction between incubation time and L-Glutamine on sperm motility and plasma membrane integrity (P<0. 05). After thawing and 3 h later، the highest of plasma membrane integrity was observed in 80 mM L-Glutamine (49. 25% and 47. 34% respectively; P<0. 05). Nine hours after thawing، the highest of sperm motility (26. 4%) was observed in 80 mM L-Glutamine (P<0. 05). Therefore، the addition of 80 mM L-glutamine to Tris-glycerol diluent (5%) improves coated sperm survival.