فصلنامه تحقیقات تولیدات دامی
سال هشتم شماره 4 (زمستان 1398)

This experiment was designed to evaluate the protective effect of nano-hydroxyapatite against freezing damages on spermatozoa using five rams. Ejaculates (N=30) were collected with three-day intervals between sessions for six times. Ejaculates were pooled and split into 12 parts at each session. The amount of 0.01, 0.02, 0.05 or 0.1% nano-hydroxyapatite and 3, 5 or 7% glycerol were added. Samples were frozen and stored for two weeks. After that two straws from each treatment for each replication (totally 144 straws) were thawed and incubated at 37 ° C for 6 h. Sperm motility, viability, membrane integrity and acrosome integrity were evaluated at 0, 3 and 6 h after thawing. Results showed that there was no interaction between nano-hydroxyapatite, glycerol and incubation time (P>0.05). Sperm viability and acrosome integrity were not affected by different levels of nano-hydroxyapatite particles (P>0.05). There was no difference between the level of 0.01 and 0.1% nano-hydroxyapatite particles on the total (21.8 and 21.5%, respectively) and progressive sperm motility (17.8 and 17.7 %, respectively; P>0.05). Total and progressive sperm motility was the highest (24.8 and 21.0%, respectively) in the level of 0.02% nano-hydroxyapatite particles (P<0.05). Membrane integrity was higher in the level of 0.02% nano-hydroxyapatite particles (52.7%) than other levels (P<0.05). Therefore, the addition of 0.02% nano-hydroxyapatite particles to the ram semen extender improved the quality of frozen spermatozoa.

This study was conducted to investigate the polymorphisms of the Prion protein gene (PRNP) exon 3 in Mehraban and Romanov sheep. Blood samples were collected from 124 sheep (85 Mahraban and 39 Romanov). After DNA extraction, polymerase chain reactions (PCR) were performed to amplify a 173 bp fragment of the PRNP gene exon 3 using a specific pair of primers. Polymorphisms of the studied fragments were explored using single strand conformational polymorphism (SSCP) and DNA sequencing analysis. In both Mehraban and Romanov breeds, three different banding patterns (AA, AG and GG genotypes) along with a single nucleotide polymorphism (g.625A>G) were identified, that deduced one amino acid substitution (p.171R>Q). Three haplotypes including ARR/ARR, ARR/ARQ and ARQ/ARQ were identified, which the most frequency (61.2 and 46.15% in Mehraban and Romanov breeds, respectively) was related to the ARR/ARR haplotype with high resistance to scrapie disease. The results of current study regarding the similarity of polymorphism in PRNP gene of domestic and foreign breeds could be used in sheep breeding programs.

The aim of this study was to investigate the effect of different levels of replacement of full fat soybean meal with soybean meal. In this study, the average daily growth rate, feed intake, feed conversion ratio, relative weight rate, specific growth rate, carcass characteristics, meat quality, and fat oxidation rate of roast muscle were measured in Zel fattening lambs. The lambs had a mean age of three months at the initiation of fattening and a weight of 19.44±0.1 kg. At 14 weeks of experiment (two weeks of habituation and 12 weeks of fattening), the lambs were divided into four treatments (0, 33, 66 and 100% high fat soybean meal replacement, respectively) and each treatment with five replicates. The results showed that the average daily growth rate, relative weight percentage and specific growth rate increased with increasing soybean percentage. At the end of the experiment, 12 lambs (three lambs from each group) were slaughtered and in carcass dissection, weight, carcass, heart, liver, four parts stomach, the hands, thighs and the shoulder and hip carcass showed significant increase by increasing the amount of soybeans diet. Taste quality, overall acceptability and meat texture were also improved (P<0.05). By increasing the shelf life of the shelf muscle (one and two months), the oxidation rate of meat fat was significantly reduced (P<0.05). The results of this study showed that the use of high-fat soybean increased the growth performance indices in lambs and also reduced the oxidation rate and improved the meat quality indices during cold storage.

The objective of this study was to evaluate the effect of corn silage as source forage and its supplementation time in starter on feed intake, growth performance and rumen parameters in suckling Holstein calves. Thirty-two Holstein calves (16 males and 16 females) from 5 d to 70 d of old were used in a complete randomized design with a 2 × 2 factorial arrangement of treatments. Dietary treatments were as follows: starter with 10% alfalfa at 5 d old calves, starter with 10% alfalfa at 30 d old calves, starter with 10% corn silage at 5 d old calves and starter with 10% corn silage at 30 d old calves. The effect of forage source and time of using forage in the starter on average daily gain (ADG), feed intake and some rumen parameters was significant (P<0.05). Effect of treatments on glucose, blood urea nitrogen concentration and fecal score was not significant. However, the effect of treatments on beta hydroxyl butyric acid concentration in calves was significant (P<0.01). Results showed that calves consumed corn silage at five d of old had the highest average daily gain, feed intake, total volatile fatty acids (VFA), propionate and acetate. According to the results of this experiment, the best time of supplementing forage in the starter diet of suckling calves is five day of old.

This experiment was conducted to evaluate dietary supplementation of different levels of sulfate, chelate and nano sources of zinc on growth performance, tissue zinc reserves and meat quality of male growing Japanese quails. The experiment was carried out using 400 Japanese quails in a completely randomized design with 10 experimental treatments and four replicates. The experimental treatments consisted of: basal diet (control group, without zinc supplement) containing 41.25 mg/kg zinc and basal diet supplemented with different sources of zinc (sulfate, chelate and nano zinc) each at three levels of 15, 25 and 35 mg/kg of diet. Birds fed basal diet + 25 mg chelate zinc/kg of diet showed lower feed intake, higher weight gain and improved feed conversion ratio compared to the control group (P< 0.05). Zinc content in serum, liver, breast meat and tibia of birds fed basal diet + 35 mg nano zinc/kg of diet were higher than the control group (P< 0.05). Malondialdehyde levels and drip losses in meat of birds fed diets supplemented with different sources of zinc were lower than the control (P<0.05). According to the results of the current study, supplementation of corn–soybean meal-based diet of Japanese quails with 25 mg zinc chelate/kg improved growth rate and feed conversion ratio compared to the control group.

In order to study theeffects of various levels of organic chromium on performanceand egg quality characteristics oflaying hens reared at high stock density, an experiment was done using twolevels of density (three and five birds per cage) and four levels of organic chromium (0, 300, 600and 900 ppb) with 192 laying hens (Hy-line W-36) in a completely randomizeddesign with factorial arrangement of 4×2 with six replicates. The results showed that dietarysupplementation of chromium at normal and high stock density had notsignificant effect on performance of layers. Egg weight significantly increasedat levels of 600 and 900 ppb (56.96 and 56.91 g) and feed intake significantlydecreased (99.34 vs. 105.05) in birds reared at high stock densitycompared to the birds reared at normal stock density (P<0.05). In thefirst four, second, and whole periods of sampling, dietary inclusion ofchromium at normal and high stock density, increased significantly egg yolkcolor and egg shell strength compared to the control (P<0.05). Dietarysupplementation of chromium at normal and high stock density had notsignificant effect on blood parameters and tibia charachteristics of layers. Ingeneral, the results of the experiment showed that by increasing dietarysupplementation of chromium at high stock density up to 900 ppb, egg yolk colorand egg shell strength significantly increased in laying hens.

The aim of this trail was to evaluate the effects of the use of Mn, Zn and Cu from different sources (inorganic, organic and hydroxy) in the diet on egg and eggshell quality of aged laying hens. A total of 240 Hy-Line w36 Leghorn, from 55 to 65 weeks of age, were used. The experiment carried out in a completely randomized design, with four treatments, four replicates, each containing 15 hens. The experimental treatments included: 1. The control diet, consisted of sulphate source of Mn, Zn and Cu, 2. The diet consisted of Mn, Zn or Cu-Methionine chelate, 3. The diet consisted of Mn, Zn or Cu Hydroxy, and 4. The diet consisted of Mn, Zn and Cu Hydroxy, only 70% level relative to treatment 3. In the most of experimental weeks, the Mn, Zn and Cu hydroxy and chelate forms increased egg weight and improved significantly feed conversion ratio in the 62, 64 and 65 weeks of age, compared with the sulphate group of these elements (P<0.05). But there was no difference between 70% hydroxy and sulphate groups. Also, there were no differences in feed intake, eggshell thickness, strength and weight, yolk index, Haugh unit, yolk color and shape index of egg and blood alkaline phosphatase, cereluplasmin, Zn, Cu and Ca levels among the treatments. The chelate source only increased blood Mn level significantly (P<0.05). There was the significant increase in eggshell and yolk Mn and yolk Zn levels and also significant decrease in the levels of Mn, Zn, Fe and Cu of excreta using hydroxy and chelate forms compared with the sulphate and 70% hydroxy forms (P<0.05). These results indicated that the Mn, Zn and Cu hydroxy and chelate forms in the diet improved the performance of aged laying hens.

The current study was carried out to investigate the effect of native fungal and bacterial recombinant phytase enzymes produced in lab with commercial sample on performance, growth parameters, Ca and P using 200 day-old Ross 308 broiler chicken which assigned in a completely randomized design to five treatments with four replicates. The experimental treatments included T1: control diet (without enzyme), T2: control diet+commercial phystase enzyme of Nataphus, T3: control diet+Bacillus subtilis enzyme, T4: control diet + E. coli enzyme and T5: control diet+Aspergillus niger enzyme. The results of this study showed that the addition of enzyme to diets decreased feed intake in grower, finishing and total period (P<0.05). Feed conversion ratio was improved due to the addition of phytase to diets in all periods (P<0.05). Time and weight at inflation point showed a significant difference between the experimental treatments and control group (P<0.05). The highest concentration of blood phosphorus at 21 days of age was observed in the group consumed commercial enzyme (P<0.05). But the amount of phosphorus and bone ash content significantly affected by the enzymes consumed (P<0.05). Overall, the addition of phytase enzyme to diets improved the feed conversion ratio and decreased feed intake compared to control group, and no significant difference was observed between commercial enzymes and enzymes produced.