نشریه پژوهش های علوم دامی
سال سی و دوم شماره 3 (پاییز 1401)

Zinc (Zn) is required for many enzymatic and metabolic functions in the animal’s body (Prasad and Kucuk 2002). Also, it affects the antioxidant defence system, where deficiency of Zn increases oxidative damage to cell membranes (Prasad and Kucuk 2002). Zn was assumed to improve the antioxidant capacity (Liu et al., 2011) since Zn is necessary for the structure and function of superoxide dismutase, which protecting the brain, lungs, and other tissues from oxidation (Noor et al., 2002). However, it has been suggested that Zn increases the synthesis of metallothionein, a cystine-rich protein that acts as a free radical scavenger (Oteiza et al. 1996). Nys et al. (1999) reported that the deficiency of Zn decreased egg production and eggshell quality linked to its role as a cofactor in the enzyme carbonic anhydrase, which is essential for shell deposition. The NRC (1994) recommends a level of 40–75 mg/kg of Zn in various poultry diets. Due to the high amount of phytate, Zn can be less bioavailable, despite the high level of Zn available in pulses and cereals. Therefore, this micronutrient can be supplemented to diets of livestock and poultry (Sahin et al. 2009). ZnO and ZnSO4 are the two most common inorganic Zn supplements used for poultry diets (Batal et al. 2001). The present study has examined the effects of Zn supplementation of laying hens on performance, egg quality traits and immune response under high stock density.

This experiment was conducted to evaluate the effects of dietary inclusion of different levels of zinc on performance, egg quality traits and immune response of laying hens under high stock density with 160 Hy-Line W-36 leghorn hens for 10 weeks. Treatments consisted of different levels of zinc (40, 80, 120 and 160 ppm) and 2 cage densities [3 hens/cage (recommended) or 5 hens/cage (high density) (38 × 38 × 40 cm)], that was performed in completely randomized design with 2×4 factorial arrangement with 5 replicates. The basal diet was formulated to meet all of the nutrient specifications according to the Hy- Line W-36 recommendations (Hy-Line International, 2007). The first 2-wk (61–62 wk of age) was considered as the adaptation period. The main trial period commenced from 63 wk of age and lasted for 8 weeks. Lighting program was set on 16 light: 8 dark using an artificial light in a windowless house. The hens had free access to feed and water at all times.The temperature was maintained at 20±2 °C throughout the study. Egg production and egg weight were recorded daily and feed intake (FI), feed conversion ratio (FCR) and egg quality were recorded weekly. Egg quality traits were evaluated every35-d period. All eggs produced during thelast2-d of each period were collected and egg quality indices including Haugh unit (HU), yolk color, egg shell thickness, andshell breaking strength were measured as followings: Each egg was weighed and the eggshell breaking strength (kg/cm2) was measured by a quasi-static compression device. The broken eggs were put onto a glass surface. The height of the albumen, midway between the yolk and the agde of the thick albumen, was measured with micrometer. Haugh units were calculated using the formula: HU=100log (H+7.57– 1.7×W0.37), where H is the mean height (mm) of the albumen and W is the weight (g) of egg (Haugh, 1937).Yolk color was visually scored by the Roche yolk colorfan. Eggshell thickness was determined on 3 points (air cell, equator, and sharpend) by using a micrometer screw gauge. In order to study immune responses, suspension of SRBC were injected into the breast muscle of two birds of each replicate at the first of 6 and 7th weeks of experiment and blood parameters were analyzed 7 days after each injection. Also reproductive parameters, blood lipid parameters were analyzed at the end of the experiment.

The results of this experiment showed that dietary supplementation of zinc in different stock density could not affect performance of layers (P > 0.05). Although, dietary increasing levels of zinc caused significant decrease in egg production percentage and egg weight during the whole period of experiment. Sorosh et al (2019) showed hens receiving 130 mg Zn/kg of diet, laid more eggs than the birds which receiving 40 and 70 mg Zn/kg of diet. Also, they reported hens receiving 130 mg Zn/kg of diet had lower feed consumption compared with the other treatments. FCR was influenced by supplemental Zn in which dietary inclusion of 70, 100, and 130 mg Zn/kg of diet improved FCR compared with that of the 40-mg inclusion level. Mirfendereski and Jahanian (2015) showed that hens in cages with higher stocking density had lower hen-day egg production, egg mass, and feed intake compared with those in normal density cages. Also they reported plasma concentrations of triglycerides and high-density lipoproteins were not influenced by dietary treatments. Sarica et al. (2008) observed that hen-housed egg production, egg mass, viability, and live weights were decreased by the higher stocking densities. In addition, the same authors reported that hens housed at the lower stocking densities reached sexual maturity significantly earlier than those in higher stocking densities. In the current experiment haugh unit was significantly lower in birds with high stock density compared with those in normal density cages. Jahanian and Mirfendereski (2015) showed that eggshell thickness was greater in hens under high stocking density challenge during the second 35-dperiod. Ovary weight was lower in hens under high stocking density challenge (P <0.05). Dietary supplementation of zinc (160 ppm) increased plasma LDL level and high stocking density increased plasma glucose level (P <0.05). The present findings indicated that dietary zinc supplementation in high stock density could not affected performance or egg quality of birds, although, levels of 120 and 160 mg Zn/kg of diet increased eggshell strength.

Low feed efficiency is one of the problems in the rumen of ruminants, which results in reduced growth and production of livestock and, most importantly, environmental pollution due to the release of methane and nitrogenous compounds . Changes in ruminal fermentation can be made to improve fermentation efficiency and substrate utilization and optimize feed nutritional value . Antibiotics have been successful in reducing energy loss (from methane) and protein (from ammonia nitrogen) in the rumen . However, today, due to general concerns about the remains of these compounds in milk and meat and thus increasing the bacterial resistance to them has caused the use of materials in feed as additive in some countries . Therefore, the tendency to find alternatives with natural origin for antibiotics has increased over recent years .Plant secondary metabolites are among the natural alternatives that have been studied in recent years that have antimicrobial properties.Essential oils, also known as volatile or ethereal oils, occur in edible, medicinal, andherbal plants. As these aromatic compounds are largely volatile, they are commonly extracted by steam distillation or solvent extraction . Essential oils can be extracted from many parts of a plant, including the leaves, flowers, stem, seeds, roots and bark. However, the composition of the EO can vary among different parts of the same plant . For instance, EO obtained from the seeds of coriander (Coriandrum sativum L.) have a different composition from the EO of cilantro, which is obtained from the immature leaves of the same plant . Chemical differences among EO extracted from individual plants, or different varieties of plants, also exist and are attributed to genetically determined properties, age of the plant, and the environment in which the plant grows . One of the plant essential oils that has a great potential for use in ruminant diets is the essential oil of thyme (Thymus Vulgaris). Thyme extract contains 0.6-8.8% (usually 1%) of essential oil, most of which are phenols (20-20%) and monoterpene hydrocarbons (such as P cymen and γ terpinen) and alcohols (such as Linalool and terpinen α). They show that sometimes these compounds make up 80% of the extract compounds. Naturally, thymol is also a major phenolic component in thyme and carvacrol is a sub – element (Leung and Foster., 1996). Although goats and sheep have often been fed and managed in a similar manner (goats being browsers and sheep being grazers), they are different, especially in their digestive capability, because of differences in the morphology of digestive system, including the mouth structure and gut, which may influence their ability to ingest and digest feed materials . Available information on efficiency of feed utilization between goat and sheep has been inconsistent with several studies reported sheep had higher growth performance than goats . In a recent in vitro study, Candyrine et al (2016) reported that goats had better rumen fermentation characteristics, including higher volatile fatty acids (VFAs) production and higher population of cellulolytic bacteria compared to sheep, suggesting that goats could be more superior in digesting feed materials.The results of studies performed on lambs and goats ) that have examined the effects of thyme extract or its major compounds (thymol and carvacrol) are very contradictory. And more research is needed to determine their effects on rumen fermentation and metabolism in lambs and goats. There is also little research on direct comparisons of the use of plant extracts in vivo between lambs and goats. Therefore, the aim of the present study was to compare these two species and the effects of thyme extract on performance and some ruminal parameters in fattening lambs and goat kids.The aim of this study was to investigate the effect of different levels of thyme (Thymus vulgaris) extract on growth performance, feed intake, daily weight gain and digestibility of nutrients in fattening lambs and kids. For this purpose, 15 goat kids (average initial BW of 17.3 ± 1.2 Kg, 3 month- old) and 15 Dalagh lambs (average initial BW of 21.4 ± 1.5 Kg, 3 month- old) were randomly assigned to 3 dietary treatments: 1) control (without thyme extract), 2) supplemented with 250 ml thyme extract and 3) supplemented with 500 ml thyme extract. Animals were kept in individual pens with self-mangers for 84 days. The results showed that there was no significant difference in nitrogen consumption through the use of extracts between different treatments. However, fecal and urinary excretion nitrogen was lower in treatments receiving 250 ml of thyme extract and retained and digested nitrogen was more than other treatments (P <0.01). Examination of interactions and species effects showed that the effect of thyme extract on excreted nitrogen and nitrogen retention in lambs was different from that of goat kids, so that excreted nitrogen was higher in goats and nitrogen retention was lower. With increasing levels of thyme extract, a significant decrease in gas and methane production was observed in both species (P <0.01). Rumen microbial population (total bacteria, coliforms and lactic acid bacteria) decreased due to the addition of thyme extract in both species, but this decrease was not significant. Also, in lambs and goats receiving thyme extract, with increasing the levels of the extract in the diet, the number of protozoa decreased significantly (P <0.01), so that the group receiving 500 ml of extract had the lowest number of protozoa. Concentrations of triglycerides, cholesterol, low-density lipoprotein and high-density lipoprotein were not affected by the use of the extract. However, blood glucose concentration increased significantly with increasing the extract in the diet and blood urea nitrogen concentration decreased (P <0.01). In general, the results of this study showed that the use of thyme extract in the diets of lambs and goats can significantly reduce gas production, especially methane gas and excretion of nitrogen through urine and feces, and thus increase nitrogen retention and digestion.

There is an increasing interest in the use of spineless cactus (Opuntia fícus-indica) as fodder for cows, goats, and sheep around the world especially in the arid and semi-arid regions. Cactus withstands water shortage, high temperature, and poor soil fertility, and thus adapted to the arid and semi-arid zones of the world. Cactus is useful not only because it can withstand drought, but also because its conversion efficiency is greater than C3 grasses and C4 broadleaves. Biomass generation per unit of water is on average about three times higher than for C4 plants and five times higher than for C3 plants.The spineless cactus has low crude protein but it has high levels of non-fiber carbohydrates (Barbera et al 1995). High levels of fermentable energy could support rumen fermentation, thus increasing microbial protein synthesis, the production of volatile fatty acids, and the subsequent nutrients supply for the host animal. Data on spineless cactus nutritive value and digestibility is scarce. Furthermore, no data is available regarding the feeding behavior of individual ewes fed diets containing spineless cactus. The objective of this study was to investigate the effects of partial replacement of corn silage by spineless cactus on feed intake, nutrient digestibility, blood metabolite, and feeding behavior of ewes.

A total of 21 Arabian ewes (37.1±1 kg live weight) were used in a completely randomized design with three treatments for 30 days. Experimental diets included control, diets containing 10 and 20% spineless cactus. Ewes were housed individually in pens (1.3 m×1.5 m) in an open shed building and were allowed ad libitum access to feed and water throughout the trial. All diets contained 60% forage (wheat straw, corn silage, and spineless cactus) and 40% concentrate (60: 40; forage: concentrate). The chemical composition of the spineless cactus is presented in Table 1. The ingredients and chemical composition of the rations fed to ewes are shown in Table 2. The ewes were fed the total mixed rations ad libitum twice daily at 0800 h and 1600 h and had free access to fresh water at all times. Feed offered and refusal of each lamb were recorded daily. Digestibility was measured by the total collection of feces during a 5-d period. Samples of ruminal fluid were collected from each ewe 3 h post-feeding using a stomach tube attached to an Erlenmeyer flask and vacuum pump. The first 50 ml of collected rumen fluid was discarded to avoid saliva contamination. The remaining was filtered through four layers of cheesecloth. Rumen fluid pH was measured using a portable pH meter. Blood samples were taken from each lamb at the same time as ruminal fluid sampling by venipuncture of the jugular vein in 10-mL tubes treated with sodium heparin. Samples were centrifuged in a refrigerated centrifuge at 850 × g for 30 min within 30 min of sampling, and the plasma was frozen at −20 °C until used. Behavioral parameters were monitored by direct observations of all ewes over the total time (min) devoted to each monitored behavior. Ewes were observed every 5 min by scan sampling, and the observer recorded the event of the behaviors. Chewing behavior was divided into eating and ruminating. An observation was defined as eating when the animal had its head in the feed bunk or was chewing or swallowing food with its head over it. Ruminating included regurgitation, mastication, and swallowing of the bolus. Activity was recorded as drinking when the lamb had his mouth in the water bowl or was swallowing the water. Self-grooming was defined as non-stereotyped licking of the body or scratching with a hind limb. Social behavior was registered when a lamb was licking or nosing a neighboring animal with the muzzle or horning. Oral behaviors included the act of licking or biting the fixtures. Resting was recorded as occurring when no chewing behavior and no apparent activity were being performed.Data were analyzed using a MIXED procedure of SAS 9.2 (SAS Institute, Inc., Cary, NC) based on the statistical model Yij = μ + Ti+eij, where Yij was the observation, μ the general mean, Ti the effect of treatments and eij the residual effect. Comparisons between treatments were completed with Tukey’s test. Treatment effects were declared significant at P≤0.05.

The intake of dry matter, organic matter, and neutral detergent fiber were higher in the control group as compared with the 20% cactus group (P <0.05). The decrease in total DMI with the increase in the proportion of cactus may be explained by the high moisture content of cactus occupying a considerable volume in the rumen, leading subsequently to limited DMI (Gebremariam et al 2006). Also, forages with high ash contents have poor DMI due to their mineral effect on rumen microbes (Ben salem et al 1996).In the diet containing 20% cactus, the apparent digestibility of organic matter was increased compared to the control (P <0.05). Ammonia nitrogen concentration, rumen pH, and protozoa population in the rumen showed a significant increase in the treatment containing 20% cactus compared to the control (P <0.05). The increase in ruminal pH with an increase in the proportion of cactus in the diet may be explained by its high content of minerals (Barbera et al 1995). An increase in rumen ammonia concentration with increased cactus inclusion rate could be attributed to the higher degradability of protein content in spineless cactus (Batista et al 2003). Blood cholesterol concentration was lower in the treatments containing 10% cactus (P <0.05). Time spent eating per gram of dry matter consumed was higher in cactus-fed sheep than in control. In the cactus-containing diets, the rate of feed intake and amount of feed consumed decreased compared to the control group (P <0.05). Sheep fed diet containing 20% cactus spent a shorter time ruminating compared to the control group.

The results of this study showed that using 20% spineless cactus in the diet replacing corn silage could decrease dry matter intake and rumination time and increase rumen pH. Spineless cactus inclusion in the diet increased organic matter digestibility. Spineless cactus is thus recommended as part of the ewes’ diet, up to 10 percent, in Iran's arid and semiarid regions.

Native fowl have become valuable genetic resources over the years due to their adaptation to harsh conditions in rural areas (Emamgholi et al 2009). Native fowl, despite their lower growth rate and lower egg production compared with broiler strains such as Ross and Cobb and layer strains such as Hy-Line and Lohman, perform much better in the rural system due to their good disease resistance and production under adverse nutritional and environmental conditions (Lakhi et al 2013). Breeding programs have a significant effect on improving the genetic structure of native fowl (Kiani manesh et al 2002). The purpose of this study was to combine the results of studies related to estimating genetic parameters for productive and reproductive traits in native fowl using meta-analysis method in order to improve the accuracy of estimations. In addition, the use of meta-analysis method eliminates the existing differences between studies by examining the heterogeneity between them (Field and Gillett 2010; Lortie et al 2013; Hooijmans et al 2014). Increasing the accuracy of estimates can consequently increase genetic improvement through selecting proper candidates to be parents of next generations. Higher performance will increase the courage of farmers to keep native fowl and therefore it help to keep the birds as a valuable genetic source for the future.

In this meta-analysis study, previous studies in the field of estimating genetic parameters of productive and reproductive traits in Iranian native fowl were collected and used. These articles consisted of 33 articles which were published between years 2007 and 2016. Information used in current study included heritability, genetic and phenotypic correlations of productive and reproductive traits. These traits consisted of birth weight, weight at eight weeks of age, weight at twelve weeks of age, egg number, egg weight, age at sexual maturity and weight at sexual maturity. Cochran test and I2 criterion were used for testing heterogenty among used articles. The range of heterogeneity among studies could be from zero to 100 percent. Ranges of 0 to 25 percent, 25 to 50 percent, 50 to 75 percent and 75 to 100 percent indicate very low, low, moderate and high heterogeneity among studies, respectively. Fixed meta-analysis model is usually recommended for very low and low heterogeneity among studies and random meta-analysis model is normally used for moderate to high rates of heterogeneity among studies. Due to high heterogenty observed among studies in present study, random effects model meta-analysis was performed using Metacor package R software version 3,3,1 and Comprehensive Meta-Analysis (CMA) software version 3. The weighted average of the heritability, genetic and phenotypic correlations were calculated accordingly.

According to the results, the highest heritability among productive and reproductive traits was related to egg weight (0.42) and then weight at sexual maturity (0.41). The lowest heritability was related to egg number with a value of 0.20 and then birth weight with a value of 0.25. The highest positive genetic correlation between productive and reproductive traits was estimated between weight at eight and weight at twelve weeks of age (0.86) and then between weight at twelve weeks of age and weight at sexual maturity (0.64). The highest negative genetic correlation was related to the correlation between age at sexual maturity and egg number (-0.66), then egg number and egg weight (-0.19). Due to combing the results of individual studies using meta-analysis, the standard error of estimations for genetic parameters and consequently their 95% confidence interval were significantly reduced compared to individual studies (Bayssa et al 2021). This reduction indicates an increase in the accuracy of the estimates due to aggregating the results of individual studies (Field and Gillett 2010). A comparison between the results of independent studies and the results of meta-analysis shows a significant reduction in estimated standard errors for heritability and genetic and phenotype correlations in the meta-analysis method. For example, the amount of estimated standard error related to heritability of weight at twelve weeks of age in the meta-analysis was calculated to be 0.0009, while the range of reported standard error in the articles for the heritability of this trait was from 0.05 to 0.08. For weight at eight weeks of age the amount of standard error of heritability in the meta-analysis was estimated to be 0.0009, but the range reported for standard error of heritability for this trait in the articles was zero to 0.06. Similar reduction in the amount of estimated standard error were observed for reproductive traits. For example for egg number, the amount of error in the meta-analysis was estimated to be 0.0013, but the range reported in the articles was 0.01 to 0.13. The amount of estimated standard error related to egg weight in the meta-analysis was calculated to be 0.0009, while the range reported in the studied articles was from 0.004 to 0.07. This decreasing trend was similarly observed for other studied traits, which is due to the aggregation of the results obtained from independent studies.

The results of this study showed that the use of meta-analysis method by aggregating the results of individual studies, will increase the accuracy of genetic parameters of productive and reproductive traits in native fowls through increasing the sample size and reducing estimated standard errors. Therefore, by taking into consideration that Iranian native fowl are economically important animals and considerable demands for their products in the country, using genetic parameters obtained from this study with higher accuracy can play an effective role in the successful design of breeding programs for native fowls and promote genetic improvement in native fowl in Iran.

Evaluation of the efficiency of broier farms can better identify the position of the units and increase the awareness of policy makers and planners as well as investors in this type of activity in the agricultural sector for decision-making principles or fix the problems. Broiler breeding in Lorestan province was the growth of relatively well in terms of employment and provision of livestock products required province despite the problems caused by lack of planning, inadequate support services, uncoordinated and executive programs and relative lack of credit facilities assigned to this sector in the past two decades (DAPI of Lorestan Province, 2018). The percentage of broiler farmers in Lorestan province was 2.5% of the total country in 2017 year,. 420 broiler farmers activated ,annually with capacity of 13 million broilers in the province of Lorestan in 2017 year. In Khorramabad city, there were 129 broiler units with a capacity of 556130 broilers in 2017. This year the production of poultry meat was 12989 tons (Statistics of Agricultural Jihad, 2018). Efficiency is one of the most important tools in analyzing the production conditions of economic units. The types of efficiencies investigated include technical, allocative, economic and scale efficiency. Technical performance efficiency represents the unit's ability to achieve the maximum possible return on resources used. Efficiency analysis is used to identify opportunities for increased production and as a complement to the set of policies adopted (Farrel 1957). ccording to the studies, estimating the efficiency and identifying the causes of inefficiency of broiler farms have a great effect on yield increase and have a significant role in reducing the cost of production units and the optimal allocation of production factors. So far no comprehensive study has been conducted to calculate and evaluate the technical efficiency of poultry farms in Khorramabad city. It is necessary to recognize the strengths and weaknesses of breeding, nutrition and reproduction management of broiler farms in Khorramabad city which can be a deterrent to production. Therefore, any action in this field can lead to increased production and economic prosperity in this profession. Therefore, in this regard, the present study investigated the efficiency of these units in Khorramabad city. In this study, it was tried to evaluate the conditions of production of broiler units in Khorramabad city by applying technical efficiency and the Stochastic Frontier Analysis (SFA) method.

In order to investigate the management and efficiency of broiler units and production function of these units, this study was conducted at Khorramabad city in 2017 year. The data collection methods were face to face interview and questionnaires. stionnaire questions were about factors affecting production such as capital, cost of feed, one day-old chickens, health, labor force, management issues, inputs including vaccine, health, energy, bedding, labour force, feed, production and income of broiler units and etc. in this farms. The number of samples was calculated based on Cochran formula 97 broiler farms. For this purpose, to random sampling, questionnaires 97 broiler farms were completed in the city of Khorramabad. The Least Squares Restricted Fisher test, in which the Cobb-Douglas production function as Restricted model and the transendental production function as Unrestricted model, was tested as follows (Gujarati 2003). The production function determined with Cobb Douglas functions and the technical efficiency were estimated by the Stochastic Frontier Analysis (SFA) method. Cobb-Douglas frontier production function of the form used is as follows: LnYi=β0+ β1lnX1i+ β2lnX2i+ β3lnX3i+ β4lnX4i+ βlnX5i + β6lnX6i +β7lnX7i +Ui . The data on production functions and coefficients maximum likelihood method (ML) were estimated by SPSS 20 and Frontier 4.1 softwares, respectively.

In terms of the cost of inputs in broier farms, the cost of feed intake (62.1%), purchase of one-day-old chicks (16.3%), fuel and electricity costs (9.7%), labor costs (4.5%), medicine and treatment (4.2%) and miscellaneous expenses (2.3%). The highest and lowest technical efficiency of broiler breeding units were 100% and 25.9%, respectively, and their average efficiency was 67.8%, which was average efficiency (Table 1). The technical efficiency of 40.2% of these units (39 units) was less than 60% (Table 2). The difference between the best production unit and the average units was 32.2%. If this difference was reduced to zero by increasing the average technical efficiency of production units, the production rate can be increased by 32.2% using existing technology and specific factors. The technical efficiency difference between the best and worst producers was about 74.1%, indicating that there was a significant difference between the broiler breeders in the province in terms of management.The highest and lowest allocative efficiency of the study population was 100% and 16.7%, respectively, and the mean was 59.4%. The range of economic efficiency changes was the best and worst productive unit (81.4%), indicating that there was a significant difference between this units in terms of economic efficiency.The results of production function showed that the variables of number of breeding chicks in year, the amount of feed intake and fuel consumption and electricity had a positive and significant effect on meat production (P<0.01). Among all variables, the amount of feed intake with a coefficient (0.472) had the greatest effect on chicken meat production. otal elasticity of production that is in fact the sum of the coefficients of the independent variables, the show returns to scale. The coefficients were statistically significant equal to one. In other words, the returns to scale are constant among the broiler farms in Khorramabad city, and the production inputs will increase by the same proportion as total production increases.

The results showed that most broiler farms had a low efficiency and profitability. Most of these broiler farms are vulnerable to bankruptcy due to lack of compliance with economic principles in management. In general, maintaining the relative stability of feed price, familiarizing the farmers with the principles of rationing and improving the conditions of broiler units such as nutrition management, breeding and health, is necessary to increase the efficiency and production in broiler units in Khorramabad city.

Spirulina platensis (SP) is a filamentous blue-green microalgae (cyanobacteria) generally regarded as prebiotic and source of high quality protein, minerals, essential fatty acids, essential amino acids, pigments and phenolic acids. Many studies have shown that Spirulina has antioxidant, immunomodulatory, anti-inflammatory, antiviral, and antimicrobial activity in various experimental animals. Several studies have demonstrated the growth-promoting effects of spirulina platensis on broiler chickens. Jamil et al., (2015) showed that feeding 0.2, 0.4, or 0.8 percent spirulina increased weight gain and linearly decreased feed conversion ratio (FCR) of broiler chickens. Similar results were reported by Shanmugapriya et al., (2015). They reported that feeding 1% of spirulina platensis to broiler chicks caused to improve growth performance. As well as growth performances, treatment with S. platensis was reported to increase the carcass percentage and ready-to-cook yields of broiler chicks in the studies of Raju et al. (2004), Kaoud (2012) and Holman & Malau-Aduli (2013). The cecum plays an important role in preventing colonization of pathogens and detoxifying harmful substances (Jorgensen et al., 1996), therefore may play an important role in improving nutrients absorption and better performance. A previous study in broiler chickens also concluded that intestinal microbial-including cecum is highly associated with the production performance of broiler chickens (Jeong and Kim, 2014). Park et al., (2018) indicated that broiler chickens fed a Spirulina supplemented diet led to higher cecal Lactobacillus concentration, but had no effect on the number of coliform bacteria. Some other studies suggest that microalgae have potential antibacterial, antiviral, and antifungal activities. de Mule et al., (1996) observed that methanolic and aqueous extracts of Spirulina inhibited the growth of Candida albicans whereas Lactococcus lactis was promoted by the extract, with growth increasing from 7.5 to 14.7%.

Three hundred one-day- old male Ross 308 broiler chicks were assigned to 5 dietary treatments with 6 replicates and 10 birds each in a completely randomized design. Dried Spirulina Platensis (SP) powder provided from Pars Jolbak Co. in Shiraz, Iran and after chemical analysis was used in diets. All experimental diets were corn soybean based and formulated to reach ROSS 308 broiler chicken requirements. Dietary treatments were 0 (control), 0.25, 0.5,0.75 and 1 % Spirulina Platensis (SP). All diets were isocaloric and isonitrogenous and were fed to birds during 6 weeks. The average daily feed intake (FI) and weight gain (WG) were measured for each group and feed conversion ratio was calculated. Daily mortality was weighed, recorded and used to correct the feed conversion ratio. Daily FI was determined from the difference between supplied and residual feed in each pen and was adjusted for mortality. At the end of the experiment, two birds per each replicate (similar to cage average weight) were selected. The birds were killed by cervical dislocation. Breast, thigh, pancreas, abdominal fat and liver were removed, weighed and expressed as a percentage of live weight at 42 d of age. At the end of experiment, cecal samples collected from each bird. One gram of cecal sample from viable counts of bacteria in the cecal samples were conducted by plating serial 10-fold dilutions onto Lactobacilli MRS agar plates and MacConkey agar plates to isolate Lactobacillus spp. and coliform bacteria, respectively. The lactobacilli agar plates were then incubated for 24-72 h at 37◦C under anaerobic conditions. After the incubation periods, colonies of the respective bacteria were counted and expressed as the logarithm of colony-forming units per gram (log10 CFU/g). All data analyzed by ANOVA using the GLM procedure described by the SAS Institute (2009). Tukey test was used to determine the significant differences between the treatment means.

The results showed that feed intake of birds was not influenced by SP supplementation during the whole period, but weight gain of birds fed diets containing 1 % SP, was increased (P<0.05) and feed conversion ratio was decreased significantly (P<0.05) as compared as control birds. Similar to our results, Park et al., (2018) showed that up to 1% SP in broiler diets, did not affect the feed consumption of broiler chickens. They showed that increasing dietary SP from 0 to 1 %, caused to increase in weight gain during total period. Shanmugapriya et al., (2015) reported that feeding 1% of spirulina platensis to broiler chicks caused to improve growth performance.The mechanism of action of Spirulina has not been clearly established, but previous studies have reported that dietary supplementation of Spirulina has positive effects on growth performance in poultry. Carcass yield and breast relative weight in chickens fed more than 0.5 % SP were significantly increased (P<0.05), but abdominal fat, liver and thigh relative weight were not affected. Similar to our results, increase in carcass percentage and ready-to-cook yields of broiler chicks were reported in the studies of Raju et al. (2004), Kaoud (2012) and Holman & Malau-Aduli (2013). In present study, the chickens fed more than 0.5% SP had lower cecal E.Coli concentration and nonsignificant increase in Lactobacillus concentration. Similarly, Park et al., (2018) indicated that broiler chickens fed a Spirulina supplemented diet led to higher cecal Lactobacillus concentration. Regard to previous study which concluded that intestinal microbial-including cecum is highly associated with the production performance of broiler chickens (Jeong and Kim, 2014), therefore in our study, the better performance of chickens fed higher than 0.5% SP may be associated with decrease in cecal E.Coli Concentration.Conclusion It is concluded that dietary supplementation of broiler diets with 1% Spirulina platensis, could improve the growth performance, carcass yield and cecal microbial population of broiler chickens at 42 day of age.Keywords: Prebiotic, Feed Conversion ratio, Carcass yield, Escherichia coli, Algae

The graphical representation of daily milk yield during lactating period is lactation curve. There are many advantages of evaluation of the lactation curve in dairy cows, such as designing suitable breeding and management strategies for dairy cattle, genetic evaluation of dairy cows, and the prediction of the total milk yield of cow To explain the flow of milk production over the course of lactation in dairy cows, various mathematical models have been developed (Wilmink 1987; Wood 1967).There are many earlier studies that have successfully applied lactation curves in modeling the milk yield-DIM of Iranian Holstein. In all of these research the classic or Frequentist statistical methods have been used for parameter estimation and statistical inferences. The parameters of these models have not been estimated for Iranian dairy cows using Bayesian method. In the Bayesian approach, the parameters of the model are random variables, and inference is made on parameters using their posterior distributions (in some cases without the assumption of normality of the studied data) and need for huge data (Iqbal et al. 2019).This study was Bayesian estimation of the parameters of Wood, Milkbot, Gompertz, Dijkstra, Cobby and Le Du, Von Bertalanffy, Brody and Logistic mathematical models for the lactation curve. This was done using 30618, 30685 and 30627 days in milk (DIM) records of milk yield, fat percentage and protein percentage, respectively. These records were related to the days of 5 to 305 days of the first lactation period of Iranian Holstein cows with 3685 cows out of 350 herds. These data have been collected by National Breeding Center and improvement of animal production of Iran in registered herds of Holstein cows.

Data were initially adjusted for significant fixed effects that were herd-test-date (HTD) and age at calving. In order to be accurate and due to the high computational needs of Bayesian method, in this study, 30618, 30685 and 30627 records of milk production test day, fat percentage and protein percentage related to the first lactation period belonged to 3685 Holstein cows out of 350, respectively. For test-day records of milk yields, an outlier control assessment was conducted. 99.73 % of the observations accounted for data within the μ ± 3 standard deviations range. Records outside this range have been taken into consideration outliers (Junior et al. 2018). Bayesian inference was used to estimate the subsequent distribution of both unknown parameters of each lactation curve model, using a mixed nonlinear model to which the random lactation effect of each cow was added to account for the individual lactation curve of each cow. The parameters of lactation curves were estimated using the cow's test day records in the MCMC procedure of SAS software. To consider the individual lactation curve of each cow, the effect of each cow was used as a random effect in all nonlinear models. For sampling of the posterior distribution of parameters, the Monte Carlo Markov chain sampling algorithm was obtained by considering the burn-in period, sampling interval (thin) and number of cycles of 150,000, 100 iterations and 400,000 cycles for each, respectively. The effective sample size and Geweke detection test was used to evaluate the sampled amount and calculate the convergence indices. Comparisons of the models were made based on the Deviance Information Criterion (DIC). To determine the significance of the difference between the two models, if the difference between the two nonlinear models was less than 10, the DIC index was considered non-significant and if it was 10 or more, it was considered significant (Iqbal et al., 2019).

By examining the statistics of functions and convergence indices, Brody function for milk production and Wood function for fat percentage and protein percentage showed the most suitable model and better fit. The Convergence has been achieved according to Geweke test (Geweke 1992) statistic P-value. In the protein percentage fitting curve, Wood model was selected despite the significance of parameter a in the Geweke test (P <0.05) due to the appropriate trace plot. Effective sample size and the simulation sample size (4000) indicate convergence in all parameters. The differences between DIC values were found greater than 10 points for most of the cases, indicating high significant difference between the fitted models. In the results, the estimated parameters of the Brody function for milk production were 37.219, 0.544 and 0.084 for a, b and c, respectively. For milk fat percentage and milk protein percentage, the estimated parameters of Wood function were 4.29 and 3.53 for a, -0.08 and -0.04 for b, -0.0008 and -0.0004 for c, respectively. For the first 30 days, a modified gamma function gave the best fit for the first lactation (Sherchland et al. 1995).The Wood curve was superior to the Gompertz function in fitting the data and, hence, it was used for biological inference (Hansen et al. 2012).In another study by Bangar and Verma (2017) to compare four nonlinear models, Wood, quadratic model, mixed logarithmic model and Wilmink to fit the shape of lactation curves of milk production and its production traits in Gir crossbred cows in India, Wood model as the best model for Fitting of milk production data and production traits were introduced.

Bayesian method can be used in modeling complex nonlinear functions for lactation curves, especially with a small amount of data. Biological interpretation of these parameters makes it possible to use these estimates in a selection index to genetically modify the lactation curve. This shows that Brody and Wood functions, respectively, as the best model in predicting milk production and production traits in Iranian Holstein cows in the first lactation period.

Genomic selection has provided the sheep industry with a powerful tool to increase genetic gains on economically important traits such as meat production (Taylor et al. 2016). In addition identifying genes with large effects on economically important traits, has been one of the important goals in sheep breeding. One way to identify new loci and confirm existing QTL is through genome-wide association studies (GWAS). QTL assisted selection and genomic regions affecting the production traits have been considered to increase the efficiency of selection and improve production performance. Genome wide association studies typically focus on genetic markers with the strongest evidence of association. However, single markers often explain only a small component of the genetic variance and hence offer a limited understanding of the trait under study. A solution to tackle the aforementioned problems, and deepen the understanding of the genetic background of complex traits, is to move up the analysis from the SNP to the gene and gene-set levels. In a gene-set analysis, a group of related genes that harbor significant SNP previously identified in GWAS, is tested for over-representation in a specific pathway. The present study aimed to conduct a genome wide association studies (GWAS) based on Gene-set enrichment analysis for identifying the loci associated with birth weight and biometric traits using the high-density SNPs.

Phenotypes records and genotypic data related to birth weight, body length, withers height and chest girth were obtained from 277 Luzhong sheep. The gene set analysis consists basically in three different steps: the assignment of SNPs to genes, the assignment of genes to functional categories, and finally the association analysis between each functional category and the phenotype of interest. Genome wide association study was performed with birth weight and biometric traits using GEMMA software. Using the biomaRt2 R package the SNP were assigned to genes if they were within the genomic sequence of the gene or within a flanking region of 25 kb up- and downstream of the gene. For the assignment of the genes to functional categories, the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway databases were used. The GO database designates biological descriptors to genes based on attributes of their encoded products and it is further partitioned into 3 components: biological process, molecular function, and cellular component. The KEGG pathway database contains metabolic and regulatory pathways, representing the actual knowledge on molecular interactions and reaction networks. Finally, a Fisher’s exact test was performed to test for overrepresentation of the significant genes for each gene-set. The gene enrichment analysis was performed with the goseq R package. In the next step, a bioinformatics analysis was implemented to identify the biological pathways performed in BioMart, Panther, DAVID and GeneCards databases.

Gene set enrichment analysis has proven to be a great complement of genome-wide association analysis (Gambra et al., 2013; Abdalla et al., 2016). Among available gene set databases, GO is probably the most popular, whereas KEGG is a relatively new tool that is gaining ground in livestock genomics (Morota et al., 2015, 2016). We had hypothesized that the use of gene set information could improve prediction. However, neither of the gene set SNP classes outperformed the standard whole-genome approach. Gene sets have been primarily developed using data from model organisms, such as mice and flies, so it is possible that some of the genes included in these terms are irrelevant for meat production. It is likely that a better understanding of the biology underlying meat production specifically, plus an advance in the annotation of the ovine genome, can provide new opportunities for predicting production using gene set information.In this research, 14 SNP markers on chromosomes 2, 3, 5, 7, 11, 13, 17, 19. 20 and 25 located in MYL1, MYL3, ACACA (birth weight), PLCB1, BMPR1A, LRPPRC, PTBP1, TMEM117 (body length), ADIPOR2, SYN3, TRAK1 (withers height) and PPARG, HMGA1 (chest girth) genes were identified. Some of the genes that were found are consistent with some previous studies related to birth weight and biometric traits. According to pathway analysis, 21 pathways from gene ontology and biological pathways were associated with the birth weight and biometric traits (P˂0.05). Among these pathways, muscle structure development, carbohydrate derivative metabolic process, anatomical structure formation involved in morphogenesis, skeletal system development, positive regulation of ossification, muscle cell proliferation and GnRH signaling pathway have important functions in development of skeletal muscle, glucose homeostasis, osteogenesis process, regulation of ion calcium and activation of the MAPK signaling pathway. Finally, it is worth noting that our gene-set enrichment analysis was conducted using a panel of SNP obtained from a single marker regression GWAS, which relies on a simplified theory of the genomic background of traits, without considering for instance the joint effect of SNP. Hence, other approaches (e.g., GWAS exploring SNP by SNP interactions) might provide a better basis for biological pathway analysis.ConclusionsIn total, this study supported previous results from GWAS of birth weight and biometric traits, also revealed additional regions in the sheep genome associated with these economically important traits, using these findings could potentially be useful for genetic selection in the breeding programs.

total, this study supported previous results from GWAS of birth weight and biometric traits, also revealed additional regions in the sheep genome associated with these economically important traits, using these findings could potentially be useful for genetic selection in the breeding programs.In total, this study supported previous results from GWAS of birth weight and biometric traits, also revealed additional regions in the sheep genome associated with these economically important traits, using these findings could potentially be useful for genetic selection in the breeding programs.

To predict body composition of growing Afshari fat-tailed lambs using the 9-11th rib composition as a predictor of whole body composition, 10 lambs were randomly selected (43.9 ± 3.9; mean shrunk body weight; mean ± SD) and harvested accordingly. After slaughter, the 9-11th rib sections were harvested from chilled carcasses for 24 h; fat, lean, fat-tail and bone were weighted separately and total separable fat (without fat-tail) and lean were grounded twice to obtain a homogenous sample for further chemical analysis. Rib dissection separable lean, fat and bone percent were (mean ± SD) 33.9 ± 6.6, 23.6 ± 6.6, and 17.3 ± 7.4, respectively. In addition, rib dissection ether extract, crude protein, moisture, and ash percent were (mean ± SD) 27.6 ± 4.1, 19.3 ± 0.7, 49.6 ± 5.3, and 1.7 ± 0.3, respectively. Except for carcass separable bone percent (with and without fat-tail), it was shown that the 9-11th physical rib composition can properly predict the carcass separable fat (adjusted R2 of 0.62 and 0.86 with and without accounting for fat-tail, respectively; P < 0.01) and lean (adjusted R2 0.77 and 0.71 with and without accounting for fat-tail, respectively; P < 0.01). As for the carcass chemical composition, with or without accounting for fat-tail, none of rib chemical commotion based on as-is analysis predicted chemical carcass composition. However, when as-is data were represented as soft tissue dry matter, only rib crude protein (%, without accounting for fat-tail) could predict carcass crude protein (adjusted R2 = 0.60; P < 0.005). In general, our results for the first time in fat-tailed sheep, showed that the 9-11th rib section can only predict physical, but not chemical, composition of fat-tailed lamb carcass.

Recent advances in nanotechnology suggest that nanoscale particles were used in medicine, dietary additives, and engineering arenas. However, their possible toxicity to people, animals, and environmental health is still unclear. The researchs showed that the ruminal fermentation of sheep with different levels of copper oxide nanoscale particles produced acetic acid and volatile fatty acid at the appropriate amount of copper oxide nanoscale particles stimulates rumen fermentation.

This investigation was designed to evaluate copper oxide nanoscale particles' supplementation with plant and animal protein types by biogas production method.

The produced gas from incubated syringes at 2, 6, 12, 24, 48 and 72 h was measured by Menke and Steinggass (1988) assay. For this purpose three amounts of 0, 30, and 60 ppm of copper oxide nanoparticles was impregnated in three types of plant proteins (soybean meal, canola meal and cottonseed meal) and three types of animal protein (poultry offal meal, fish meal and blood meal) and were applied in a completely randomized plan by three replications and two-run (a total of 6 repetitions).

The obtained results indicated that after 72 h, the highest of produced gas achieved for soybean meal from plant protein (58.4 mL/200 mg dry matter (DM)) and in animal protein sources was obtained for fish meal (36.7 mL/200 mg DM). The higher digestible organic matter (DOM) and short-chain fatty acids (SCFA) were related to soybean meal, and the smaller of them was related to a blood meal. Also, the higher metabolizable energy (ME) of soybean meal for the quantities of zero were 30 and 60 ppm of copper oxide nanoscale particle, 6.48, 5.65, and 6.52 MJ/Kg DM, and the lower values of this case was found for blood meal 3.07, 3.91, and 4.01 MJ/Kg DM, respectively. The maximum and minimum amounts of microbial protein (MP) were achieved for soybean meal and blood meal 52.92 and 22.17 g/kg DOM, respectively.

As a whole, copper oxide nanoscale particles could be improved fermentation parameters in some of the protein types.