JOURNAL OF RUMINANT RESEARCH
Year:2021 | Volume:9 | Issue:1|Papers Count:7

Background and objectives: Information from RNAs helps to understand the biological aspects of physiological pathways because they are the link between genotype and phenotype. MicroRNAs are molecules with 22 nucleotides in length and a 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 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 a complex network which indicates the association of a large number of biological pathways with a lot 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 present study aimed 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. Materials and methods: 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 the present study, all stages of standardization of data, differences between the 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<0. 05 and 1< Log fc <-1. Next, bioinformatics tools were used to find the target gene for each microRNA. The microRNAs with different expressions derived from the analysis in the previous step were introduced to TargetScan software for finding target genes. After identifying target genes for each microRNA, DAVID server was used for the investigation of biological data and functional analysis. Results: 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 traits. Conclusion: MAPK1, MAPK8, FASLG and PTEN genes are activated in most biological pathways and they are associated with various genes, accordingly, these genes are the major genes in the process of milk production.

Background and objectives: The polymorphisms in the major genes of Diacylglycerol OAcyltransferase 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 association between these genes and milk production traits has been reported incompatible (sometimes significant and some other times without significant association) in dairy cattle. The purpose of the present study was to investigate the association between DGAT1 and Leptin genes and some economically important traits including milk yield, milk fat and protein content and percentages in dairy cows by using meta-analysis. Materials and methods: All researches published in the theses and peer-reviewed journals up to 2018 were used. Following quality control, 9 and 4 studies reported for the polymorphisms of K232A in DGAT1 and Sau3AI of Leptin gene were used, respectively. The analysis of the current study was carried out using the Stata v. 15. The Non-conformance index (I2) was significant for all parameters so that a random risk model was used. The effect size, 95% confidence interval, and statistical significance level of the measurements were calculated for each variable using this model. All variables were continuously in the current study. The measurement of the effect size for continuous data was carried out using the standardized mean difference (SMD) that was calculated for the polymorphisms of K232A and Sau3AI loci in DGAT1 and Leptin genes on the milk yield, milk fat and protein content and percentage. Results: The results of the present research showed that the polymorphism in the K223A locus of DGAT1 gene, has a significant effect on milk fat content and percentage, and can play an important role in 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. Conclusion: The results of the present 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 in planning the use of the polymorphisms of these genes in future researches.

Background and objectives: The trend of changes in agriculture and animal husbandry during the last half-century in Iran has been such that the livestock population has increased significantly and consequently the nutritional needs of livestock have also increased. In Iran, sheep breeding is a major part of livestock activities. Providing food during a fattening period accounts for about 65 to 70 percent of the cost of raising and maintaining livestock. Feed processing is one of the methods which increase feed efficiency. Alfalfa and barley grain are two important ingredients for livestock, therefore, the nutritional value of the feed can be improved by physical and chemical processes to increase the nutritional value of feed and improve production efficiency. Material and methods: In order to investigate the effects of alfalfa physical form and processing of barley grain on yield and nutrient digestibility in 30 Dalagh fattening lambs, 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, Experimental variables include: the physical form of forage (pellets and chopped) and barley grain processing (whole, ground, flakes). The experimental variables include: the 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. Experimental diets include: 1-Alfalfa with whole barley; 2-Alfalfa with ground barley; 3-Alfalfa with flaked barley; 4-Pelleted alfalfa with whole barley; 5-Pelleted alfalfa with Ground barley; 6-Alfalfa pelleted with flaked barley. Results: There was a significant difference between different treatments in terms of weight gain. The treatments that used pelleted alfalfa in comparison with chopped alfalfa had a higher final weight (42. 81 kg compared to 41. 50 kg) and also, had a higher daily weight gain in the whole period (297 gr compared to 282 gr). The dry matter consumption of the whole period in the treatments receiving pelleted alfalfa was 1933 gr and higher than the treatments receiving chopped alfalfa 1883 gr and also the use of pelleted alfalfa improved the feed conversion ratio in the third month. The dry matter digestibility, crude protein and crude fiber insoluble in neutral detergent was also higher in pelleted alfalfa treatment compared to chopped alfalfa and barley grain processing had a significant effect on final weight gain. The final weight was significantly higher than barley flour and whole barley grain in treatments receiving flaked barley, respectively. Also, the daily weight gains in the whole period in the treatments receiving barley flakes and ground, and whole barley grains were 294 gr, 289 gr and 287 gr. Also, the digestibility of crude protein in the treatments receiving barley flakes, ground barley, and whole barley were 63. 96, 62. 98 and 61. 95, respectively. Conclusion: Feed processing, which in this study included the processing of alfalfa forage in the form of pellets compared to chopped, increased feed consumption and daily weight gain and overall higher final weight and improved dry matter and crude protein digestibility and also, barley grain processing in the form of flakes and ground compared to whole barley also increased dry matter consumption and improved dry matter and protein crud digestibility.

Background and objectives: 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 the 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 forms of zinc, copper, manganese, and selenium with organic sources on starter intake and growth performance of Holstein suckling calves. Materials and methods: 30 Holstein calves (42± 2 kg of birth we ight ) were equally assigned to two groups of 15 (5 males and 10 females) 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 the treatment group and copper sulfate, manganese oxide, zinc oxide, and sodium selenite in the 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 the 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: Results showed that starter intake and feed efficiency increased significantly by 85. 6g and 6. 44% respectively in the treatment group. Calves were fed with organic form showed a higher average daily gain (P<0. 001). No significant difference was found in blood parameters, serum levels of copper and zinc. However, the level of manganese in blood serum was significantly higher in the treatment group. It was not found significant changes in the 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 the calves were fed the organic form (P≤ 0. 01). Conclusion: 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 forms is recommended in mineral supplements of calf starter.

History and Objectives: Supplying the needs of dairy cows in the period of early lactation, when they have low dry matter intake and high protein requirements is important. Methyl groups are not synthesized in the body of living organisms, however, they 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. Therefore in the present study, the nutritional effects of protected betaine at one level and unprotected at two levels on the plasma parameters of Holstein dairy cows were examined. Materials and methods: 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 a history of at least two deliveries were randomly used in 5 eight-head treatments. The experiment lasted one month (the first 14 days for the adaptation period and the next 16 days for 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 produced-protected betaine. The cows received a perfectly mixed basal diet containing the above betaine additives in two promises (10 am and 10 pm). The amount of dry matter intake for each treatment was measured daily and blood samples were also taken at the beginning and end of the experiment. Data analysis for feed consumption and plasma parameters were performed by SAS software using mixed procedure. Results: 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 produced protected betaine 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 treatments decreased compared to other groups and at P <0. 05 it was significant. Conclusion: The results of the current 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 produced-protected betaine compared to the control group in dairy cows. Therefore, the use of 50 g of produced-protected betaine in the early stages of lactation is recommended.

Background and Objectives: In recent years, researchers have focused to find out the best dietary composition to provide maximum performance and health for the animals. 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 growth performance in calves. However, the relationship between the level of forage consumption and the type of fat source in the infant’ s calves is not well understood. Therefore, the current study was designed and conducted to evaluate the effects of fat sources with or without alfalfa hay forage in the starter diet on performance, nutrient digestibility, and blood and rumen parameters of Holstein dairy calves. Materials and Methods: 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. Results: 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 (635 vs. 443 g/d), daily gain (541 vs. 671 g/d) and final weight (71. 2 vs. 79. 6 kg) were found when palm fat and soybean oil was fed with alfalfa hay, respectively. Dry matter intake (milk + starter) and feed efficiency were not 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 was related to the treatment of palm oil with alfalfa and the lowest amount was found for soybean oil with alfalfa. The highest concentration of ammonia nitrogen was for calves receiving soybean oil with alfalfa, where 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 the short-chain fatty acid concentration (P <0. 05). Rumen pH, acetate and propionate concentrations, 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 any significant effect on blood concentrations of cholesterol, triglycerides, albumin, blood urea nitrogen, aspartate aminotransferase, and alanine aminotransferase. Conclusion: It can be concluded that despite the level of forage in the starter diet, supplementation with soybean oil reduced performance, nutrient digestibility, and also impaired ruminal fermentation compared to the diet containing palm oil. 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.

Background and objectives: 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. Thus, it is possible to change the growth curve in the population by selecting animals based on the growth curve components in breeding programs. 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. Materials and methods: 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. Results: 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 AB, A-K, and B-K were 0· 06, 0· 03, and − 0· 0003, respectively. Conclusion: 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.