Hamed Mohammadi

This study investigated the interactive effects of total mixed ration (TMR) forage level (10% vs. 20% DM) and provision timing (starting at 28 vs. 56 days) on growth, blood metabolites, rumen fermentation, and skeletal development in Holstein calves. Forty-eight calves (43 ± 5 kg) were assigned to four treatments in a 2×2 factorial completely randomized block design with 12 replications. Calves fed 10% forage TMR exhibited significantly higher dry matter intake, body weight, and average daily gain during pre- and post-weaning periods than those fed 20% forage (P < 0.001). However, the 20% forage diet unexpectedly improved feed efficiency during the post-weaning period (60–75 days; P < 0.001). Serum urea, AST, albumin, and total protein were higher in 10% forage calves (P < 0.05), indicating enhanced anabolic status. Rumen pH was higher in the 20% forage group at 75 days (6.16 vs. 5.62; P < 0.05), while the 10% forage diet increased propionate and butyrate proportions (P < 0.05). All skeletal parameters (withers height, hip height, hip width, chest circumference, body length) were greater in 10% forage calves (P < 0.01), with a significant forage level × timing interaction for chest circumference (P < 0.001). The timing of TMR introduction had limited independent effects but interacted with forage level for several parameters. We conclude that a 10% forage TMR maximizes structural growth and rumen development in Holstein calves, although the superior post-weaning feed efficiency of the 20% forage diet presents a trade-off worthy of further investigation for systems where feed costs are primary constraints.

This study investigated culling reasons in 27 industrial and semiindustrial dairy farms (15,907 cattle) in western Tehran Province, Iran, using records from 2010–2014 (with detailed analysis for 2012–2014). Herds were stratified by size: 20–100, 101–200, 201–500, and > 500 head. Milk yield increased with herd size (6955 to 8750 kg), while fat (4.06% to 3.86%) and protein (3.28% to 3.20%) decreased, showing strong negative correlations with yield (−0.79 to −0.89 for fat; −0.77 to −0.88 for protein) and positive correlations between fat and protein (0.91–0.94). Involuntary culling predominated (70%–76%), with reproductive disorders (15%–20%), mastitis (13%–15%), lameness (15%), and low milk yield as primary causes. Larger herds exhibited higher involuntary culling for health‐related issues, consistent with findings that high milk yield is associated with deteriorated cow health and fertility. Herds of 201–500 head demonstrated optimal balance between productivity (mean 32 kg/day, 3.1% fat) and lower culling rates for mastitis, udder disorders, and lameness compared to larger herds. These findings indicate that targeted management and breeding strategies—including fertility‐focused selection and proactive health monitoring—could reduce involuntary culling by 10%–15% and enhance herd sustainability in Tehran’s dairy industry.

Background: Animal food shortage and finding efficient ways to produce poultry products are getting more and more important issues in the world.Objectives: This study was aimed to determine the effect of replacing corn with pasta wastes (0%, 50% and 100%) in the diet on production performance, some blood variables and the egg quality traits of laying quails.Methods: A total of 240 laying quails were allocated into 3 experimental groups with 8 replicates for 8 weeks. Egg production percentage, egg mass, feed intake and also mortality rate and percentage of abnormal eggs, egg quality traits and blood variables were evaluated.Results: None of the pasta wastes inclusion had significant effect on egg mass, abnormal egg percentage, mortality rate, yolk diameter, yolk weight, albumen height, yolk index, shell weight percentage, egg shape index and blood parameters (except for triglycerides). Replacing 100% corn with pasta by‐product reduced feed conversion ratio and increased egg weight values. Replacing 100% corn by pasta wastes significantly increased the albumen weight, shell weight and also egg length and width and decreased the Haugh unit. Replacing 50% and 100% corn had a significant increase in yolk height, egg surface area and significantly decreased shell thickness and yolk colour. Overall, 100% replacement of corn by pasta by‐product increased blood triglycerides compared to the 50% group.Conclusions: Based on the result of current experiment, total replacement of corn with pasta wastes could increase the egg weight and also improve feed conversion ratio in the laying quail diets.

Background: Organic products for animals are becoming more widely accepted by consumers. Using herbal additives may lead to more healthy animal products. In this research, it is hypothesized that thyme essential oil (TEO) and/or selenium yeast (SY) would be helpful to enhance production performance in broilers.Objective: In the current study, the effects of adding TEO and/or SY to the diet on broiler performance and blood parameters were evaluated in broiler chickens.Methods: A total of 480 chicks were distributed in 24 cages with 20 chicks (10 males and 10 females) each and assigned to be fed four iso‐caloric and iso‐nitrogenous diets including two levels (0 and 250 mg/kg) of TEO and two levels (0 and 0.3 mg/kg) of SY in a 2 × 2 factorial arrangement with six replicates.Results: Adding SY significantly decreased feed intake in finishing period (22–42 d) (p < 0.05). Supplementation with SY and TEO significantly decreased plasma uric acid and triglyceride levels, respectively (p < 0.05). However, neither of the supplements had any influence on the plasma glucose and albumin levels (p > 0.05). The lowest level of plasma cholesterol was detected in the birds fed the TEO‐supplemented diet (p < 0.05). Addition of SY significantly increased blood glutathione peroxidase activity (p < 0.05).Conclusions: Dietary supplemental TEO has a favourable effect on feed intake, weight gain, and body weight values. Besides, SY may decrease blood concentration of uric acid, as well as blood glutathione peroxidase activity. An interaction is detected between TEO and SY on blood cholesterol.

Objectives: The effects of dietary supplements, including magnesium sulfate (Mg), zinc oxide (Zn) and vitamin B6 (Vit B6), on the performance of laying hens reared under normal (NC) and heat‐stress (HSC) conditions were investigated.Material and Methods: A total of 288 30‐week‐old Lohmann LSL‐Lite laying hens were randomly divided into 48 cages and assigned to receive one of the eight diets with six replicates and six hens per replicate, based on a 2 × 2 × 2 factorial arrangement of treatments. Dietary supplements, including two levels (0 & 600 mg/kg) of Mg, two levels (0 & 30 mg/kg) of Zn and two levels (0 & 8 mg/kg) of Vit B6, in normal and heat‐stress conditions, were tested at 30–40 and 41–45 weeks of age, respectively.Results: In the Vit B6 group, a decrease in feed intake (FI), egg production (EP), albumin, Zn, Fe and Mg, and an increase in triglyceride and insulin in HSC were observed, in addition to a decrease in cholesterol and an increase in egg weight (EW) in NC. Supplemental Mg decreased EP, blood triglycerides and copper in NC, and Zn, Fe and Mg in HSC as well. Feeding Zn, increased egg shape index, total protein and copper in addition to yolk index in NC and Fe in HSC. EWs were higher in hens supplemented with Vit B6+Mg in HSC. Increased insulin and decreased glutathione peroxidase activity were detected with the Vit B6+Zn compared to feeding either Vit B6 or Zn in HSC.Conclusions: The results indicated Vit B6 could improve EWs and suppress blood cholesterol in NC. Zn improved the egg shape index in NC.

In this study, 160 73-week-old laying hens (HyLine W-36) were used to investigate the changes in production performance and egg quality parameters of aged laying hens after injection of different doses of growth hormone (GH) and a fixed dose of testosterone (Ts). The hens were weighed individually, placed in laying cages and then randomly assigned to four treatments with four replicates of 10 birds each, in a completely randomised design. The experiment was started at the 75th week and lasted until the 82nd week of age. The treatments were: 1: injection of 100 µL distilled water (control group), 2: injection of 500 µg Ts/kg liveweight + 50 µg GH/kg liveweight, 3: injection of 500 µg Ts/kg liveweight + 100 µg GH/kg liveweight and 4: injection of 500 µg Ts/kg liveweight + 150 µg GH/kg liveweight. In this study, ovulation rate (egg production percent), egg mass and feed intake were significantly higher in Treatment 3 than the control group (P < 0.05), and in Treatment 4, feed conversion ratio was significantly higher than for the other experimental groups (P < 0.05). In addition, the birds in Treatment 3 showed greater egg weight, albumen height, eggshell weight, eggshell density and eggshell weight per surface area than the control group (P < 0.05). In Treatment 3, egg length significantly increased compared with Treatments 1 and 4 (P < 0.05), and in Treatments 2 and 4, shell breaking strength was significantly lower than for the control group (P < 0.05). In conclusion, our results showed positive effects of GH and Ts administration on egg quality parameters and production performance in aged laying hens. Taken together, in the present study Treatment 3 was found more effective in improving egg quality and production performance of the old laying hens.

The experiment was designed to study the changes in some blood parameters and production performance of old laying hens after injection of different doses of growth hormone (GH) and testosterone (Ts). A total of 160 old laying hens (HyLine W-36) at 73 weeks of age were weighed individually and randomly allocated to four treatments with four replicates and 10 birds in each replicate in a completely randomized design. Growth hormone and Ts hormones were injected subcutaneously. Treatment groups were as follows: treatment 1: injection of 100 μl distiled water (control group), treatment 2: injection of 500 μg Ts/kg live-weight + 50 μgGH/kg live-weight, treatment 3: injection of 500 μgTs/kg live-weight + 100 μgGH/kg live-weight and treatment 4: injection of 500 μgTs/kg live-weight + 150 μgGH/kg live-weight. Plasma levels of oestradiol, T4 , LDL, HDL and cholesterol significantly increased in treatment 3 in relation to the control group. All injected hens showed significantly higher levels of glucose in relation to control group. The results showed the positive effects of GH and Ts administration on production performance and blood parameters which are associated with egg production potentiality and in turn may improve reproductivity (egg production) in old laying hens. The positive results of the study may be useful in animal selection and breeding programmes.