فصلنامه تحقیقات تولیدات دامی
سال دهم شماره 1 (بهار 1400)

Introducing new lines to produce high-quality silkworm hybrids is one of the ongoing tasks of the silkworm breeding centers. Five lines of Y, 124, 154, 104, and 32 with Chinese-shaped cocoons were selected from the gene bank. Based on the diallel cross, 20 genetic compounds were reared massively over three generations. After establishing the basic generation with 14 genetic combinations, the multi-trait selection was performed for five generations by the independent culling levels method. To compare the performance of parental lines and their combinations, data on the four traits of cocoon weight, cocoon shell percentage, good cocoons percentage, and cocoon number/liter (cocoon size) statistically analyzed in each year and the overall five years. The mean of cocoon weight and cocoon shell percentage of all genetic combinations were higher than the parental lines (p < /em><0.05). The average response to selection for cocoon shell percentage was more than one percent in the three genetic combinations compared to the maternal parent. For the good cocoons percentage, the best combinations had no significant difference with the best lines (104 and Y). While cocoon size in one genotype (IRA14) was very large (94 cocoons/ liter), other genotypes of large cocoons did not show significant differences with those lines with large cocoons (154 and 124). Genetic improvement of cocoon weight was positive for 12 out of 14 genetic combinations, but only one of them increased more than 0.1 g. The best lines will select finally after doing the crossbreeding program of Chinese with Japanese lines.

Data mining explores hidden and invisible relationships and patterns in the vast amount of data without which these relationships may never be revealed. Determining the factors affecting dystocia in dairy cattle can help to find the weaknesses of the management of the dairy cattle industry and the resulting problems. Therefore, it is necessary to identify and manage the most important of the various genetic and non-genetic factors that affecting dystocia. The feature selection algorithm is one of the data mining methods that can be useful in this field. This study aimed to determine the most important factors affecting the dystocia of Holstein dairy cows using the feature selection algorithm. The total records were 413205, along with 14 features related to reproductive and production records. Data analyzed with four important methods of feature selection algorithm (Best-First, Greedy-Stepwise Genetic-search, and Ranker) and nine different models (CFS-Subset-Eval, Gain-Ratio-Attribute-Eval, etc.) to determine the most important factors. The results showed that the genetic-search method using Naive Bayes Tree classification of the feature selection was the most appropriate method for selecting the factors affecting dystocia with the lowest error rate (AMS = 0.011, ARAE = 0.001). The most important factors affecting dystocia were milk production, dam age at parturition, parity, gestational length, corrected milk based on 4% fat, calf sex, calf weight, the season of calving, type of calving, fat-to-protein percentage ratio, and open days. It is expected that by considering these factors, dystocia can be better managed in dairy cattle enterprises.

Purslane (Portulaca oleracea L.) is a weed forage that can grow in most parts of Iran; however, the nutritional value of this plant has been less considered. Therefore, the present study aimed to determine the chemical composition and in vitro fermentation parameters of fresh and ensiled portulaca oleracea with or without wheat bran. Purslane was harvested during the flowering stage and ensiled in polyethylene containers for 60 days. Experimental treatments included: 1) fresh purslane, 2) purslane silage without additive, 3) purslane silage+16% wheat bran (fresh weight), and 4) purslane silage+32% wheat bran (fresh weight). The crude protein of the four treatments ranged from 19.27% to 26.86%. The highest concentration of ammonia nitrogen (10.85% of total nitrogen) and pH (4.72) of silage extract were observed in silage without additive, but the concentrations of lactic acid and total volatile fatty acids were highest in the silages containing wheat bran (P<0.05). After ensiling, the true digestibility of organic matter (71.03%) and dry matter (70.05%), as well as potential gas production (28.90 mL), showed a significant decrease compared to fresh purslane (P<0.05). In general, purslane had a favorite protein content and digestibility in animal feeding. Although the nutritional value of fresh purslane was higher in comparison with silage, ensiling can reduce the problems of drying. Purslane silage without additive had low dry matter content and contained mildew, but the quality of purslane was improved when wheat bran was added to the silage.

This experiment was conducted to determine the effect of corn silage particle size, homofermentative and heterofermentative fermenting bacteria inoculation on chemical compounds, sensory evaluation, aerobic stability, and gas production on days 30, 45, 60, and 90 after silage preparation. The corn forage was harvested in coarse and fine sizes (16 and 8 mm, respectively), and the silage was prepared in nylon bags with a size of 90×45 cm (4050 cm2). During the preparation of the silage, bacterial inoculation was added to 50 percent of coarse and fine corn forage. Silages were sampled at 30, 45, 60, and 90 days after the preparation of silage. On the 90th day after silage preparation, the score of total sensory evaluation of silages was higher in inoculated silage (p < /em><0.05). On the 45th and 60th days after silage preparation, pH was the highest in fine silage (3.77 and 3.80, respectively) (p < /em><0.05). The crude protein content of silage was higher in fine silage only on day 90. The percentage of the neutral detergent fiber was the highest in coarse and non-inoculated silages on day 30 after the preparation of silage (p < /em><0.05). Aerobic stability was higher in coarse and inoculated silages on day 45 (p < /em><0.05). The gas production potential (A+B) in fine silages was the greatest on day 90 after the preparation of silage. The results of the experiment showed that the effect of particle size on the quality of silage was greater than bacterial inoculation, but inoculation of bacteria increased the aerobic stability of silages.

In this study, the effect of forage:concentrate ratio on growth performance, nutrient digestibility, and rumen parameters in male Lori Bakhtiari Lambs was investigated. A total of 27 male lambs (70 ±15 days of age, mean live weight of 26.3 ± 3.3 kg) were fattened for three months with three different levels of concentrate (55, 70, and 85%) and three different fattening period duration (first, second and third months). The apparent digestibilities of rations were measured monthly using acid-insoluble ash as an internal marker. Ruminal fluid samples were taken to determine the ruminal fermentation parameters at the end of each month. The results showed that increasing the level of concentrate improved daily weight gain and decreased feed conversion ratio (P<0.05). Increasing the diet concentrate level resulted in a decreased ratio of acetate to propionate and isobutyric acid concentrations (P<0.05). The ratio of acetate to propionate and daily weight gain decreased with increasing fattening period duration (P<0.05). In contrast, feed conversion ratio, ammonia concentration, and protozoa count increased. Interactions between diet concentrate level and fattening period duration had significant effects on final body weight, feed intake, nutrient digestibility coefficients, propionic acid concentration, and acetate:propionate ratio (P<0.05). In conclusion, the positive effects of concentrate level on performance, nutrient digestibility, and volatile fatty acid production were affected by the duration of the fattening period. Therefore, it is better to shorten the duration of the fattening period when using a high concentrate diet, and the maximum dietary concentrate level should be equal to 70% if the duration of the fattening period is increased.

This experiment was conducted to investigate the effect of wheat particle size and different levels of enzyme on performance, carcass traits, and small intestine morphologyof Japanese quails. A 3 × 3 factorial arrangement in a completely randomized design was used in nine experimental treatments replicated four times with 20 birds per replicate. The investigated factors were three wheat grain particle sizes (2, 3, and 3.5 mm) and three levels of dietary enzyme supplement (0, 200, and 400 ppm). The measured traits included: performance, carcass traits, and small intestine morphology. The results showed that the dietary enzyme significantly reduced feed intake and feed conversion ratio (P<0.01). The effect of wheat particle size on feed intake, body weight, and feed conversion ratio were also significant (P<0.01). The interaction effect of wheat particle size and enzyme affected significantly feed intake and feed conversion ratio through the experimental period from 7-35 days of age (P<0.01).Relative weights of proventriculus, gizzard, and liver were significantly reduced by enzyme supplementation (P<0.05). The relative weight of the breast significantly increased by dietary enzyme addition (P<0.01). Enzyme supplementation also significantly increased the villi length of the jejunum (P<0.01). In conclusion, dietary inclusion of wheat grain at 2 mm diameter particle size supplemented by 400 ppm enzyme is recommended.

This study was performed to investigate the effect of dietary supplementation with Manna of Alhaji Maurum (Tarangabin) powder on performance, carcass traits, serum biochemistry, and jejunum histology parameters in broilers. The experiment was arranged in two separate sections, in the first section, 400, day-old male broilers (Ross 308) were randomly assigned to five treatments with four replicates. The dietary treatments consisted of the basal diet as control, control + 0.5% Manna in starter, control + 0.5% Manna in starter and grower, control + 1% Manna in starter, control + 1% Manna in starter and grower. In this experiment, supplementing the diet with 0.5% Manna in starter and grower periods increased the body weight of broilers at 10, 24, and 42 days of age (P<0.05). The higher average daily gain was observed at 1-10, 11-24, and 1-42 days of age with 1% Manna treatment in starter and grower periods. The treatment of 1% Manna in the starter period had the greatest villus height that had a significant difference with control treatment (P<0.05). It can be concluded that 0.5% Manna in starter and grower periods can be used as an additive for improving performance traits and 1% Manna in starter for jejunum morphology traits in broilers.

In this study, a total number of 144 Lohmann LSL-Lite laying hens (41 weeks old) were randomly assigned to 24 groups (four treatments with six replicates of six birds each). The hens were fed to diets supplemented with 0 (control), 1, 2, or 3% saffron petals (SP) for the 8-week trial period. The treatments did not influence production performance parameters, albumen weight, yolk weight, Haugh unit, egg shape index, yolk index, shell weight, eggshell thickness, and egg gravity (P>0.05). Diets supplemented with 2 or 3% SP improved yolk color compared to the group that received 1% SP and also the control group (p < 0.05). The hens received SP produced eggs with significantly lower content of yolk cholesterol (p < 0.05). Diet supplemented with 2% SP significantly increased blood glucose compared to the groups that received 1 or 3% SP (p < 0.05). Diet supplemented with 3% SP significantly decreased blood triglycerides compared to other groups (p < 0.05); besides, 3% supplementation with SP significantly decreased blood LDL compared to 1% SP and the control group (p < 0.05). The hens who received SP (1, 2, or 3%) had significantly lower blood cholesterol levels compared to the control group (p < 0.05). Based on the results of the present study, SP may improve yolk color and decreased yolk cholesterol.