مجله پژوهش در نشخوار کنندگان
سال نهم شماره 1 (بهار 1400)

Information from RNAs, because they are the link between genotype and phenotype, helps to understand the biological aspects of physiological pathways. MicroRNAs are molecules with 22 nucleotides in length and single strand which can specifically affect the function and expression of genes, hence many studies have been done on the role of these molecules in various biological processes, such as milk production. The milk production trait is one of the most important traits in the dairy cattle industry. This trait is a polygenic trait in farm animals and controlled by a large number of genes and each gene may be involved in various biological pathways and mutually any biological pathway can include a large number of genes. These relationships form the complex network which indicates the association of a large number of biological pathways with lots of genes. Signal molecules that can act as morphogens control the pattern of the gene network of tissue structure throughout the lifespan of the growing embryo stage to the adult organism. The morphogens depend on the amount of secretion and the destination of secretion source can produce different cellular responses. Therefore, the aim of the present study was to investigate target genes of differentially expressed microRNAs in bovine mammary tissue to identify a number of biological pathways involved in the milk production process.

In order to identify and investigate the biological pathways involved in milk production, microRNA sequenced data were used which were extracted from ArrayExpress database with E-GEOD-61227 access number. In present study, all stages of standardization of data, differences between expression of microRNA and significance determination were performed by GEO2R software. The criteria for the selection of microRNA in this study were corrected P-value

The results of this study showed that there are 23 microRNAs with different expressions that affect many genes. These genes are involved in the signaling pathways of TGF-β, WNT, MAPK, mTOR, PI3k-Akt, insulin, estrogen and prolactin. Most of these signaling pathways are involved in cell growth and proliferation, mammary gland development, and epithelial cell activity. Since these identified pathways are associated with milk production, the genes identified in these signaling pathways can be used to improve milk production trait.

MAPK1, MAPK8, FASLG and PTEN genes are activate in most biological pathways and they are associated with various genes, accordingly these genes are the major genes in the process of milk production.

Meta-analysis is a statistical approach for combining the results from independent studies with the same assumptions, that is able to increase the statistical analysis power and the repeatability of the results in the livestock researches, comparing to single-study analysis. The polymorphism in the major genes of Diacylglycerol O-Acyltransferase 1 (DGAT1) and Leptin have drawn much attention from animal scientists during recent years, for their possible roles in the economically important traits. However, the relationships between these genes and milk production traits have been incompatible in dairy cows, it means sometimes significant and some other times no significant association has been reported. The purpose of this study was to investigate the overall effect of DGAT1 and Leptin genes on some economically important traits including milk yield, fat and protein content and percentages in dairy cows by using meta-analysis.

in this study, all researches published in the validated journals and thesis up to 2018 were used. Following to quality control, 9 and 4 studies reported for K232A and Sau3AI polymorphisms of DGAT1 and Leptin genes were used, respectively. The analysis was carried out using the Stata v. 15. Non conformance index (I 2) was significant for all parameters, so that a random risk model was used. Data were analyzed for each variable using these models for measuring the effect size, 95% confidence interval and statistical significance level of the measurements. All variables were continuously in this study. The measurement of the effect size for continuous data was carried out using the standardized mean difference (SMD) that calculated for the polymorphisms of K232A and Sau3AI loci in DGAT1 and Leptin genes on the milk yield, fat and protein content and percentage.

the results of this study showed that the polymorphism in the K223A locus of DGAT1 gene, has a significant effect on lipid content and percentage, and can play an important role in increasing of their amounts, but its relationship with milk yield and protein content and percentage is not significant. Also, the results for Sau3AI polymorphism in the Leptin revealed that this locus had no significant effect on the traits investigated in this study.

Overall, the results of this study with identifying the overall effects of the studied genotypes of DGAT1 and Leptin genes on milk production traits in dairy cows can play an important role for planning next researches in this field.

The trend of changes in the situation of agriculture and animal husbandry in Iran during the last half century has been such that the livestock population has increased significantly and As a result, the nutritional needs of livestock have also increased. In Iran, sheep breeding is a major part of livestock activities. Irregular grazing has caused incessant erosion of pastures and Rising demand for meat has led producers to move from a grazing system to a dense production system, or in other words, a sheep fattening systemt providing food in a fattening period accounts for about 65 to 70 percent of the cost of raising and maintaining livestockt Therefore, physical and chemical processes can increase the nutritional value of feed and improve production efficiency.

In order to investigate the effect of physical form of alfalfa fodder and barley grain processing on yield and nutrient digestibility in fattening lambs of 30 Dalagh breed, 3.5±1/2month-old male lambs with an average weight of 17 ± 1.1 were used. These experiments were statistically analyzed in a factorial experiment based on a completely randomized design with two factors. The experimental variables include: physical form of forage and barley grain processing. In the 98-day period (14 days of habituation and 84 days of the main period) with 6 treatments and 5 replications, the experimental diets were equal in terms of protein and energy content. Consumed feed and the rest of feed were weighed daily and the animals were weighed on an empty stomach every two weeks, after 16 hours of hunger using a digital scale And all statistical analyzes of this design were performed in SAS software version 1/9.

There was a significant difference between different treatments in terms of weight gain. The treatments that used pellet alfalfa in comparison with chopped alfalfa had a higher final weight of 42.81 compared to 41.50 and also had a higher daily weight gain in the whole period of 297.49 compared to 282.94. The dry matter consumption of the whole period in the treatments receiving pellet alfalfa was 1933.49 gr and higher than the treatments receiving chopped alfalfa 1883/76 gr and also the use of pellet alfalfa improved the feed conversion ratio in the third month. Feed digestibility was higher in pellet alfalfa treatments and digestibility of dry matter, netrul detergent fiber and crude protein were statistically significantly different in different treatments. Barley grain processing had a significant effect on end-to-end weight gain and end-of-period weight was reported to be significantly higher than ground barley and whole barley grain in treatments receiving flake barley, respectively. Also, the daily weight gain in the whole period in the treatments receiving barley flakes and ground and whole barley grains were 294.05, 289.40 and 287.20, respectively. Treatments receiving flake barley, ground barley and whole barley grain had higher digestibility of crude protein from 63.96, 62.98 and 61.95, respectively, from right to left.

Forage processing of alfalfa and barley grains means that in the whole processing of feed of fattening lambs, it increases the feed consumption and increases the daily weight and in total a higher final weight in fattening lambs, Also, animal feed processing improves feed efficiency and increases digestibility.

Considering that trace elements play an important role in growth performance and immune system in livestock. Nowadays, inorganic forms (mineral salts) of these minerals are added to mineral supplements. Because of mineral interaction, inorganic forms have lower bioavailability in gastrointestinal tract. One of the ways to increase the availability of trace minerals in the digestive tract of livestock is to replace their organic form (chelate with peptides and amino acids) in mineral supplements. For this purpose, the effects of organic sources of trace minerals on livestock performance have been studied. The objective of this experiment was to investigate the effect of replacement of inorganic form of zinc, copper, manganese and selenium with organic source on starter intake and growth performance of Holstein suckling calves.

30 Holstein calves (42 ± 2 kg of birth weight) were equally assigned to two groups of 15 (5 male and 10 female) control and treatment. The experiment was conducted in a completely randomized design and lasted for 80 days. The experiment was started at 4 days of age and calves were weaned at 70 days of age and were kept up to 80 days in individual hutches. All calves were equally fed with same starter. Chelated copper, zinc, manganese and yeast selenium in treatment group and copper sulfate, manganese oxide, zinc oxide and sodium selenite in control group were added to the starter. Weight and starter intake of calves were measured weekly and daily, respectively. Blood parameters and serum levels of zinc, copper, manganese, and glutathione peroxidase and superoxide dismutase enzymes were measured at the start of experiment and at the time of weaning. Calf feces were collected at the end of the experiment and after preparing the samples by wet ash method (AOAC, 984.27); fecal excretion of copper, zinc and manganese elements was analyzed.

Results showed that starter intake and feed efficiency increased significantly by 85.6g and 6.44% respectively in treatment group. Calves were fed with organic form showed higher average daily gain (p < 0.001). No significant difference was found in blood parameters, serum levels of copper and zinc. However, level of manganese in blood serum was significantly higher in treatment group. It was not found significant changes in level of glutathione peroxidase, superoxide dismutase, β hydroxybutyrate and immunoglobulin G in both groups (P≥0.05). In this study, Fecal excretion of manganese, zinc, and copper decreased significantly by 25%, 16%, and 22% respectively for calves were fed the organic form (P≤0.01).

This study showed that replacing inorganic forms of manganese, zinc, copper and selenium with their organic source had positive effects on growth performance and feed efficiency of suckling Holstein calves. Therefore, total replacement of copper, manganese, zinc and selenium with their organic form in mineral supplements of calf starter is recommended.

Supplying the needs of dairy cows in the early lactation period that have low dry matter intake and high protein requirements is important. Methyl groups are not synthesized in the body of living organisms, but are supplied through feed sources such as betaine, choline, pyridoxine and methionine. Of the three sources (choline, betaine, and methionine) that have the methyl group in their structure, only betaine can be directly involved as a methyl group donor in the transmission cycle of this group in the liver, and many key bodily functions such as Growth, liver safety (effective role in fat metabolism and liver protection) and lactation are affected, so in the present study, the nutritional effects of protected betaine at one level and unprotected at two levels on bovine plasma parameters Holstein Dairy Cows was examined.

To Investigate the nutritional effects of protected and unprotected betaine on plasma parameters of dairy cows, 40 Holstein dairy cows (Average production 38 ± 2.1 kg and lactation days 5 to 35 days) with history of at least two deliveries were randomly used in 5 eight -head treatments. The experiment lasted one month (the first 14 days of the adaptation period and the next 16 days of the main experiment period). Experimental diets included: 1- control diet 2- diet containing 50 g of unprotected Betaine supplement 3- Diet containing 50 g of externally produced protected Betaine supplement 4- Diet containing 100 g of unprotected Betaine supplement; 5- Diet containing 50 g of protected Betaine produced. The cows received a perfectly mixed base diet containing the above Betaine additives. In two promises (10 am and 10 pm). The amount of dry matter consumed for each treatment was measured daily and Blood samples were also taken at the beginning and end of the experiment. Analysis of feed consumption data and plasma parameters were performed by SAS software and Mixed procedure.

In this experiment, no significant difference (P>0.05) in the amount of glucose, cholesterol, triglyceride, calcium, phosphorus and magnesium was observed between the experimental groups. The amount of non-esterified fatty acids (0.576 mm/l) and beta-hydroxy butyrate (0.428 mm/l) in the group receiving protected betaine production was lower than the other groups and their difference was significant at the level of P=0.0001 In addition, the amount of liver enzymes such as aspartate aminotransferase (5.11 IU/L), aspartate aminotransferase (56.1 IU/L) and alkaline phosphatase (0.396 IU/L) in the five treatment decreased compared to other groups and at the level (P <0.05) Became meaningful.

The results of the present experiment showed that there was a significant decrease (p < 0.05) in the amount of non-esterified fatty acids, beta-hydroxy butyrate and the amount of plasma liver enzymes due to the consumption of protected betaine produced compared to the control group in dairy cows. therefore, the use of 50 g of protected betaine produced in the early stages of lactation is recommended.

In recent years, researchers have focused to find out the best dietary composition to provide maximum performance and health for the animal. Therefore, providing suitable nutritional conditions is aimed to improve the growth performance of calves. There are reports of the use of dietary fatty acids to alter growth performance as well as the immune response in suckling calves. Using a fat source is suggested as a way to improve energy and improve calf growth performance. However, the relationship between the level of forage consumption and the type of fat source in infant calves is not well understood. Therefore, a study was designed and conducted to evaluate the effects of fat source with or without alfalfa hay forage in the starter diet on performance, nutrient digestibility, and blood and rumen parameters of Holstein dairy calves.

This experiment with 40 newborn Holstein calves with a mean age of 3 days and a mean weight of 39 ± 1.8 kg with 4 treatments and 10 replications was a factorial arrangement in a completely randomized design. Experimental treatments were included: 1) starter diet containing soybean oil supplement without alfalfa; 2) starter diet containing soybean oil supplement with 15% alfalfa; (3) starter diet containing palm oil supplement without alfalfa; 4) starter diet contained palm oil supplement along with 15% alfalfa hay. Daily starter intake and 10-d intervals body weight were recorded and the feed conversion ratio was calculated for each group. To determine blood parameters on day 36 of experiment, blood samples were taken from the jugular vein. Apparent digestibility of nutrients (organic matter, dry matter, NDF, crude protein and ether extract) was measured using acid-insoluble ash as an internal marker.

The results showed that feeding alfalfa hay along with soybean oil could negatively affect the starter consumption, average daily gain and final weight of suckling calves. Thus, the lowest starter consumption, daily gain and final weight were found when soybean oil was fed with alfalfa hay. Dry matter intake (milk + starter) and feed efficiency did not be affected by oil, alfalfa forage and their interactions. The results showed that the digestibility of organic matter in the treatment containing soybean oil with alfalfa was the lowest (P < 0.05). The highest digestibility is related to the treatment of palm oil with alfalfa and the lowest amount is found for soybean oil with alfalfa. The highest concentration of ammonia nitrogen was for calves receiving soybean oil with alfalfa and the lowest amount was related to the treatment of palm oil with alfalfa (P <0.05). The results showed that alfalfa, oil and alfalfa and oil interaction had a significant effect on short chain fatty acid concentration (P <0.05). Rumen pH, and acetate, propionate concentrations and acetate to propionate ratio and short chain fatty acids were not affected by alfalfa, oil and their interactions. Oil supplementation and the interaction could have a significant effect on blood concentrations of glucose, insulin and beta-hydroxybutyrate (P <0.05). While soybean oil, alfalfa and the interaction of oil and alfalfa did not have significant effect on other metabolites.

It can be concluded that despite the level of forage in the starter diet, soybean oil supplementation compared to the diet containing palm oil reduced performance, nutrient digestibility and also impaired ruminal fermentation. Simultaneous feeding of soybean oil and alfalfa forage had a negative effect on feed intake and performance of dairy calves, and on the other hand, when consuming forage during the pre-weaning period of calves, the use of palm oil is more advisable rather than soybean oil.

The traits of economic importance such as body weight at different ages and growth rate in sheep are used as selection criteria in breeding programs. Growth can be defined either as an increase in the number of body cells or an increase in body weight and volume over a period of a lifetime. Animal growth curves can be described using various mathematical models. Growth curve components are heritable in different species. Therefore, the genetic potential of animals can be predicted for growth curve components. The best function describing the growth curve can vary depending on the breed and population under study. The aim of the present study was to investigate the ability of different nonlinear models to fit the growth curve of Moghani sheep and to estimate the genetic parameters of the growth curve characteristics in this breed.

In the current study, the data related to the body weights of Moghani sheep collected at the Moghani sheep breeding station in Jafarabad, Moghan, during the years 1989 – 2016 were used to investigate the growth curve and estimating the genetic parameters of the growth curve characteristics in this breed. Four nonlinear models including Brody, Logistic, Gompertz and von Bertalanffy were used to describe the growth curve of Moghani sheep. All models were fitted on the body weight records of animals at different ages using the NLIN procedure of SAS 9.0 software. The models used have three components including A (maturity weight), B (initial weight of animal) and K (maturity rate). Goodness-of-fit indices including coefficient of determination (R2), Root-Mean-Square Error (RMSE) and Akaike information criterion (AIC) were used to select the best model. After fitting the nonlinear models and selecting the best model, the components of the growth curve of individual animals were estimated using the best nonlinear model. Then, non-genetic factors affecting the growth curve components were investigated using the GLM procedure of SAS. Six univariate animal models that differed in terms of maternal permanent environmental effects and maternal genetic effect as well as covariance between direct and maternal genetic effects were used to analyze the traits. Also, three bivariate analyzes between growth curve components were performed to estimate the genetic correlation between traits.

According to our results, the logistic model with the lowest MSE and AIC and the highest R2 was the best model to describe the growth curve of Moghani sheep. The estimated values for the maturity weight (A), initial weight of animal (B) and maturity rate (K) by the logistic model were 40.328, 7.582 and 0.0270, respectively. The fixed effects of lamb sex, birth type, year and month of calving as well as dam age at calving had a significant effect on the components of the growth curve. Between the six fitted linear models, models number six, two and four were selected as the best models to analyze the components of maturity weight (A), initial weight of animal (B) and maturity rate (K), respectively. Direct heritability for maturity weight (A), initial weight of animal (B) and maturity rate (K) were estimated to 0.17, 0.08 and 0.19, respectively. Estimates of genetic correlation obtained from bivariate analysis between A-B, A-K and B-K were 0•06, 0•03 and −0•0003, respectively.

Among the four nonlinear models used, the logistic model had the best fit for the growth of Moghani sheep. According to the results of our study, the growth curve components of this breed had an acceptable heritability, so that these traits could be used in breeding programs to alter the growth curve and improve the growth pattern of animals in this breed.