مجله پژوهش در نشخوار کنندگان
سال یازدهم شماره 4 (زمستان 1402)

In recent years, due to human concerns about the emergence of antibiotic-resistant bacteria strain, especial attention has been paid to plant essential oil and extracts as replacer for growth promoter antibiotics. The results of in vitro studies have shown that essential oils and their constituents have the potential to alter ruminal fermentation and improve energy utilization in ruminants. One of the plants that has been recently considered is cinnamon with the scientific name of Cinnamomum verum. Therefore, this experiment was performed to investigate the effect of cinnamon essential oil on performance, nutrient digestibility and rumen fermentation in feedlot lambs.

This experiment was carried out in a repeated measurement design (three one-month periods) with four treatments in a completely randomized design with using 20 Kurdish male lambs (n=5, average weight of 26.15 ± 4.06 kg) in the research farm of the faculty of Agriculture at University of Kurdistan. Treatments were: 1) Basal diet without cinnamon essential oil (control), 2) Basal diet plus 0.5 ml of cinnamon essential oil per head per day, 3) Basal diet plus 1 ml of cinnamon essential oil per head per day and 4) Basal diet plus 2 ml of cinnamon essential oil. Lambs were fed 2x /d at 0730 and 1800 with the daily essential oil dose provided at the 0730 feeding. Lambs BW was recorded before the morning feeding on d 0 and again on d 24 of every period using a digital scale. To determine the amount of dry matter intake, the amount of supplied feed and its residue was measured daily for each animal during the last week of every period. Nutrients digestibility was measured by acid-insoluble ash as internal marker. On the 24th day of each period, 4h after morning feeding rumen liquid samples were taken from lambs to measure NH3-N, pH and volatile fatty acids concentration.

Dry matter intake, final body weight and average daily gain did not affected by cinnamon essential oil supplementation. Apparent digestibility of dry matter, organic matter and NDF was not affected by the treatment (P> 0.05); while, total tract apparent crude protein digestibility in lambs fed one ml/d of cinnamon essential oil increased compared to those of the lambs fed 0.5 and 2 ml of cinnamon essential oil (P<0.05). Adding cinnamon essential oil had no significant effect on the total volatile fatty acids concentration and the molar proportion of acetate, propionate, butyrate and isovalerate. Rumen ammonia nitrogen concentration in lambs fed diets containing 1 and 2 ml of cinnamon essential oil increased compared to those of the control group (P<0.05).

The results of this study showed that cinnamon essential oil at used amount and in the condition of the present study could not affect performance, nutrients apparent digestibility (except for crude protein), and rumen fermentation (except for ammonia nitrogen) in feedlot mal lambs. The results suggested that in feedlot diets included cinnamon essential oil, it is better to use of protein sources with lower rumen digestibility.

Drought have had adverse effects on the animal husbandry industry and has caused a decrease in livestock population and performance. In this regard, changing the cultivation pattern and replacing water-resistant species can be a suitable solution for this problem. However, due to low protein and dry matter (DM), animals fed exclusively with cactus pear may show weight loss, and digestive disorders such as diarrhea. Combining cactus, which is high in soluble sugars, with high fiber and raw protein ingredients could complement each other's weaknesses and form a balanced diet. Therefore, this study aimed to investigate the effect of feeding different levels of cactus-alfalfa mixed silage on nutrient digestibility, rumen fermentation, and blood parameters.

The silage was prepared from a homogeneous blender of 66% fresh spineless cactus (Opuntia ficus indica) and 34% alfalfa hay on a w/w basis using 220 L plastic gallons. The chemical composition and quality of the ensiled material were determined. The samples were taken to determine the chemical composition after ensiling on day 45. In this experiment, four Kermani male sheep were used in a change-over design with four periods of 21 days. Experimental treatments were based on increasing levels of cactus-alfalfa mixed silage (0, 10, 20, and 30% DM). During the week of sampling the amount of feed offered and leftovers were collected and weighed daily before the morning feeding to measure daily feed intake (on a DM basis) and digestibility of nutrients. On the last day of each period at 0, 2, 4, 6, and 8 h after morning feeding, rumen fluid was sampled from sheep (by esophagus tube and was filtered through three layers of cheesecloth) to determine pH, ammonia nitrogen (NH3-N), and volatile fatty acid (VFA). Blood samples were collected on the four days of each period and three h after morning feeding in 10 ml. To determine the amount of allantoin and microbial protein synthesis, the daily urine produced during 24 hours was collected.

The gas production volume (ml) was a significant difference among experimental diets (P<0.05). Fat and neutral detergent fiber (NDF) digestibility increased when animals were fed 30% cactus-alfalfa mixed silage than those fed 10% and 20% cactus-alfalfa mixed silage and control diet (P<0.05). Also, there was a quadratic effect on DM, organic matter (OM), and acid detergent fiber (ADF) digestibility by feeding different levels of cactus-alfalfa mixed silage (P<0.05). The highest concentration of ruminal NH3-N was observed by an experimental diet containing 30% cactus-alfalfa mixed silage in all sampling occasions (P<0.05). Feeding of 20% and 30% of cactus-alfalfa mixed silage than after treatments increased linearly ruminal propionic acid molar and decreased linearly acetic acid and acetate/propionate ratio (P<0.05). There was a significant effect on concentrations of triglyceride and urea-nitrogen by adding different levels of cactus-alfalfa mixed silage (P<0.05). Blood Urea nitrogen level in sheep-fed cactus-alfalfa mixed silage was significantly increased linearly (P<0.05).

The results of this study indicated that cactus-alfalfa mixed silage has appropriate nutritional value and its inclusion up to 30% on DM basis in the diets provided favorable conditions for ruminal function and digestibility. Therefore, it is recommended, cactus-alfalfa mixed silage could be included in livestock diet during drought or feedstuff shortage especially in arid and semi-arid regions.

Institutional credits are one of the main policy-making tools for the growth of production and the use of new technologies in agricultural development. Credits play a major role in providing capital needed for the development of agriculture and animal husbandry sub-sector. Institutional credits are types of directed credits that are granted to individuals with the aim of expanding and growing agricultural and livestock production.

Considering the importance of institutional credits, in this research, it has been tried to investigate the effect of institutional credits on the production and profitability of the industrial cattle farms of the Gorgan District by using the primary data collected through questionnaires and face-to-face interviews with livestock farmers. For this purpose, 40 questionnaires were distributed among the industrial cattle farmers of Gorgan district. In this study, the effect of institutional credits on the number of livestock was estimated using a multivariate linear regression model with the help of Eviews software.

The results showed that the variables of the amount of credits received, income and capital had a positive effect on the number of livestock (P<0.05). Also, variables such as loan interest and the amount of credits received had a positive and significant effect on the amount of milk production (P<0.05), but the effect of the variable number of livestock on the amount of milk production had a negative and insignificant effect. In addition, in this study, the factors affecting the demand for agricultural credits by industrial cattle farmers were also examined, and the results indicate that income and cost variables have a positive and significant effect on the amount of credit demand at the level of 5%, the capital factor also has an effect has a negative and significant effect at the level of 5% on the amount of demand for credits.

The results show that providing capital and granting institutional credits have a positive effect on the amount of income, capital, and production in cattle farms. Therefore, in order to progress and prevent the bankruptcy of the units, one of the main conditions for the development or the start of the construction of the production unit is the provision of capital. The most important sources of this capital in most countries, including Iran, are institutional credits or loans from Banks and cooperatives. Therefore, providing capital through institutional credits or loans from Banks and cooperatives can have a positive effect on the performance of animal husbandry units.

Spirulina is a microscopic unicellular algae that grows in fresh water and has a simple structure but a complex composition. This algae contains rich sources of various nutrients that have antioxidant properties and probiotic properties and can be suitable substitutes for antibiotics and can be used specifically as growth stimulants and improvement of feed conversion ratio in Holstein calves. The aim of this research was to investigate the effects of using spirulina algae on the growth performance, blood parameters and some enzymes of the immune system of suckling Holstein calves.

To perform this experiment, 32 female Holstein calves between the ages of 1 to 5 days and the average weight of 37.2±2 kg were selected in a completely random design with 4 treatments and 8 replications. The experimental treatments included: 1) basic diet without additives, 2) basic diet with 1% spirulina algae, 3) basic diet with 2% spirulina algae, 4) basic diet + 3% spirulina algae based on the dry matter of the diet.

The data showed that the addition of 3% level of spirulina algae in the ration of suckling calves increased the final weight compared to the control group (P<0.05). Daily weight gain of suckling calves due to the addition of spirulina algae tended to be significant, so that the calves receiving 3% spirulina algae had a greater daily weight gain compared to other experimental treatments (P<0.06). Feed consumption and feed conversion ratio of suckling calves were not significantly affected by feeding spirulina algae. Addition of spirulina algae increased the body length of suckling calves at 30 days compared to the control treatment (P<0.05). Also, the height from the withers and breast circumference of the suckling calves at 30 and 75 days old increased by receiving 1 percent algae (P<0.05). The use of spirulina algae in the diet of infant calves did not have a significant effect on the blood concentration of glucose, triglyceride, albumin and blood urea at 30 and 65 days. Cholesterol concentration decreased in 30 days by adding 2% spirulina algae (P<0.05). On the other hand, the use of 2% spirulina algae increased the total protein concentration compared to the control group (P<0.05). The blood concentration of beta-hydroxybutyrate increased with the addition of 1 and 2% spirulina algae (P<0.05). The concentration of alanine aminotransferase and aspartate aminotransferase was not affected by spirulina algae. The concentration of superoxide dismutase increased significantly after 30 days in the groups receiving one percent algae (P<0.05). The concentrations of glutathione peroxidase, malondialdehyde and total antioxidant capacity were not affected by the use of algae in the diet of suckling calves.

In general, the use of spirulina algae at the level of 3% based on the dry matter of the starter diet of Holstein suckling calves was able to increase superoxide dismutase at 30 days of age and total antioxidant capacity, the final body weight and daily weight gain at 75 days of age and at the level of 2% the concentration of beta-hydroxybutyrate and protein. It increased the total in 75 days and decreased the blood cholesterol at the level of 2% at 30 days and at the level of 1% at 75 days. Therefore, to increase the calf's immune system, it is recommended to use spirulina algae at the level of 3% based on the dry matter of the Holstein calf's starter diet.

Identification of several genomic markers sequenced in farm animal enable us to study the structure of their genome. Samples from different parts of the world are usually used for sequencing genomic markers. Information on the sequence of specific markers of domestic animals of each geographical area will improve our knowledge about their genomic structure. The sequence of specific genome markers for Iranian native sheep were not yet identified. Present study aims to identify single-nucleotide polymorphism (SNPs) influencing important economic and physiological traits of Iranian domestic and wild sheep as candidate markers using selection signature.

In order to identify significant genetic variants under selection in domestic and wild sheep, the whole genome sequence of 20 domestic (Ovis aries) and 14 wild sheep (Ovis orientalis) obtained from the Next Gene project was used. After doing quality control, variant under selection were detected using statistical methods consisting iHS and XP-EHH. Genetic variance for identified variants were estimated. The genetic variance of known variants in Merino, Suffolk, texel and Afshari were also estimated. The threshold for selecting variants based on iHS and XP-EHH methods were considerd to be 99.9% in domestic sheep and 99.9% and 0.001% in wild sheep, respectively. Finally, variants with genetic variances higher than 0.25, were identified and suggested as candidate markers.

In present study, 170 genomic variants with iHS and XP-EHH values higher than 3.83 and 3.44 in domestic sheep and 150 genomic variants with iHS values higher than 3.05 and XP-EHH values lower than -4.43 in wild sheep were identified and suggested as candidate markers. Genetic variance of these variants were 0.27 to 0.50 and the genetic variance of known variants in Merino, Suffolk, Texel and Afshari were from 0.02 to 0.50. This comparison shows the importance of identified variants in Iranian domestic and wild sheep. Most of identified variants in domestic and wild sheep associated with economically important traits including carcass, milk and wool related traits. The ontology of genes related to identified variants showed that these variants are located near genes related to metabolic process of production and reproduction traits

Present results showed that there are many significant genetic variants associated with economic traits in domestic and wild Iranian sheep which are not included in the commercial sheep arrays available in the market. Identification of new SNPs related to economic traits in domestic and wild sheep may help to improve the studies related to genomic structure of Iranian sheep. These results together with similar studies could be efficiently used for producing SNP arrays designed for Iranian native sheep.

The majority of selection and breeding programs for sheep focus on improving weight and growth traits. Body weight uniformity is a crucial economic characteristic within the industry of sheep breeding. Birth weight is an important trait that has an optimal limit, and extremely high or extremely low birth weight can cause difficulties during birth, stillbirth, and problems such as dystocia, stillbirths, and diminished growth of lambs. The existence of genetic variability for the residual variance is a necessary condition for improving this trait through breeding. Recent studies have demonstrated that the residual variance is governed by additive genetic influences. The enhancement of uniformity in body weight traits can be achieved as an economic advantage by employing selection strategies that take into account the genetic variability of the residual variance. The present study was undertaken to ascertain variance components and genetic parameters pertaining to the residual variance of birth weight and weaning weight traits in Sangsari sheep. Also, the genetic correlation between these traits and their residual variance was calculated.

To carry out this study, the phenotypic data of 5986 lambs obtained between 1986 and 2016 from the Sangsari sheep breeding station were utilized. The traits examined comprised birth weight, weaning weight, and the residual variance associated with them. To incorporate fixed factors into the model and assess their impact on the examined traits, a least-squares analysis was conducted utilizing the GLM procedure of SAS software. The estimation of variance components and genetic parameters was conducted using the average information restricted maximum likelihood (AI-REML) algorithm implemented in the DMU software, employing the DHGLM method. Firstly, an animal model was applied to estimate the residual variance of birth weight and weaning weight traits. Following that, a bivariate model was employed to examine the influence of additive genetic effects on the residual variance.

The additive genetic standard deviations for the residual variance of birth weight and weaning weight were determined to be 7.74 and 17.90, respectively, consequently, a decrease of one standard deviation in the breeding value of residual variance resulted in a reduction of 7.74 and 17.90% in the uniformity of the respective traits. The heritability estimates for the mean and residual variance of birth weight and weaning weight were found to be 0.26 ± 0.09, 0.059 ± 0.003, 0.23 ± 0.06, and 0.037 ± 0.001, respectively. The genetic coefficient of variation was determined to be 0.58 for birth weight and 0.48 for weaning weight. The genetic correlation ranged from -0.16 for birth weight and residual variance to 0.11 for weaning weight and residual variance.

The results of the current study offer crucial information regarding the presence of additive genetic variation for the residual variance of birth weight and weaning weight within Sangsari sheep herds, which can be utilized to enhance uniformity by selecting for reduced residual variance. The selection for increasing birth weight resulted in a reduction of the breeding value of residual variance and an enhancement of herd uniformity, owing to the favorable genetic correlation observed between birth weight and its residual variance. The genetic correlation for weaning weight was found to be unfavorable, indicating that selecting for higher weaning weights led to increased heterogeneity within the herd.

The growth and health of lambs from birth to weaning are influenced by yield and quality of the ewe's colostrum. Colostrum contains essential proteins, fats, hormones, vitamins, and antibodies that facilitate immunity, growth, and development. Therefore, to improve colostrum, it is necessary to use a quality diet. That colostrum is of high quality to ensure the best start to life for offspring. Consumption of high-quality colostrum improves neonatal survival and increases the reproductive potential and future productivity in sheep. Some plant essential oils have been used to improve ewes health and their productivity. This experiment was conducted to evaluate the effect of feeding different levels of Pistacia Atlantica Kurdica gum essential oil on feed, intake, the quality of colostrum, milk yield, and milk composition, and growth of suckling lambs.

Pistacia Atlantica Kurdica gum essential oil was prepared commercially and added to the ewes' diet in order to influence the Pistacia Atlantica Kurdica gum essential oil during pregnancy and lactation (it lasted for 5 months and the habituation time was 21 days). A herd of 168 ewes (which were in the second and third pregnancy and the average weight of the ewes was 68.84±1.65 kg), all of which were subjected to the estrus synchronization program. Ninety pregnant ewes in the last month of their pregnancy were randomly divided into three groups. The first group did not receive any essential oil, and the second and third groups received a daily dose of 0.8 and 1.6 milliliters of Pistacia Atlantica Kurdica gum essential oil, respectively. The Pistacia Atlantica Kurdica gum essential oil was sprayed on the feed of just before each meal. At the time of parturition, 36 single-born female lambs and their dams were randomly assigned to the three experimental groups. Each group was further subdivided into 4 units of three ewes each to determine dry matter intake. All other data such as milk production and composition, colostrum, and lambs growth data were obtained from 12 ewes and their lambs in each treatment.

Both groups treated with Pistacia Atlantica Kurdica gum essential oil had positive effects on increasing dry matter and milk production, but ewes received a daily dose of 1.6 ml of Pistacia Atlantica Kurdica gum essential oil had the highest DM intake and milk production (P<0.05). The essential oil had no effect on the birth weight of lambs (P<0.05). Feeding the essential oil had a significant effect on fat, protein, and solid none fat in colostrum and milk. Somatic cells both in colostrum and milk declined as a result of feeding Pistacia Atlantica Kurdica gum essential oil(P<0.05).

The essential oil had a significant and positive effect on the somatic cells of colostrum and milk and caused it to decrease in the treatments containing essential oil. Because of the significant positive effect of Pistacia Atlantica Kurdica gum essential oil on milk production, milk and colostrums composition (fat and protein) and the growth rate of suckling lambs, it is concluded that this essential oil could be recommended as a suitable feed additive in the diet of ewes at a dose of 1.6 ml/d.

Lipidol contains a number of active lysophospholipids, which because of its unique structure, increases the absorption of nutrients by changing the cell membrane and stimulating absorption channels. Due to the similarity of the structure of lipidol and absorption areas of the intestine, this increase in absorption takes place without spending excess energy and can facilitate the absorption process and thus reduce the feed cost. Regarding the use of lipidol supplement in the starter of suckling calves, no report was found in scientific sources. This study was conducted to investigate the effect of 0.5% and 1% levels of lipidol supplementation on growth performance, blood and rumen parameters of Holstein suckling calves.

18 male calves aged 3 to 5 days (44±3 kg) were randomly divided into 3 equal groups and each group was assigned to one of the treatments. The experiment lasted for 60 days. Experimental treatments included 1- basal diet (control), 2- basal diet plus 0.5% lipidol supplement, and 3- basal diet plus 1% lipidol supplement. Lipidol supplement was added daily to the milk consumed by calves. During the experiment, the amount of feed intake was determined daily. Weighing using a digital calf scale, and measuring skeletal growth indices including withers height, hip height, hip to pin distance, hip to hip distance, pin to pin distance, heart girth, and body length using meter and caliper, were done every three weeks. At the end of the experiment, 3 hours after the morning feeding, blood samples were taken to measure the plasma concentration of total protein, urea, glucose, triglyceride and cholesterol (Pars Azmoon kit, auto-analyzer), and rumen fluid was collected to measure pH and ammonia nitrogen concentration (phenol hypochlorite method, spectrophotometer device). The data related to growth performance, and blood and rumen parameters were analyzed according to completely randomized design, and those related to skeletal growth indices were analyzed in accordance with the repeated measure design in SAS software.

Performance traits were not affected by the use of lipidol supplement (P>0.05). Hip height in calves receiving 1% lipidol showed a tendency to decrease compared to the control group (P=0.074). Other skeletal growth indices were not affected by the treatments (P<0.05). The use of 1% level of lipidol increased the level of total protein (P=0.041). Lipidol decreased blood urea level (P=0.050). Adversely, blood cholesterol level tended to increase due to the use of this supplement (P=0.072). The highest amount was observed at the level of 0.5% lipidol. Levels of 0.5 and 1% lipidol decreased ammonia nitrogen (P<0.0001) and pH (P=0.025) of rumen fluid compared to the control.

In general, the use of 0.5 and 1% levels of lipidol supplement did not have a significant effect on the performance of Holstein suckling calves. It is suggested that higher levels of this supplement be investigated in future studies.