مجله پژوهش در نشخوار کنندگان
سال هشتم شماره 2 (تابستان 1399)

Meta-analysis method was used for gathering studies done on genetic parameters estimation in Holstein cows to increase the accuracy of estimations. For this purpose, data from 96 articles on genetic parameter estimation of productive and reproductive traits on Iranian Holstein dairy cows were used. Productive traits were milk production, amount of milk fat, amount of milk protein, milk fat percentage and milk protein percentage and reproductive traits were age at first calving, calving interval, dry days, open days, pregnancy period and lactation period.

First, heritability estimates, genetic and phenotypic correlations were obtained from articles. After data preparation, the meta-analytical model with random effects using Metacor package, R 3.3.1 software and CMA ver.3 software were used for estimating weighted average of heritability and genetic and phenotypic correlations, standard errors and 95% confidence interval for productive and reproductive traits. Investigating available studies showed high heteroginty among studies. Therfore, using fixed model meta-analysis was not possible for estimating weighted average of effects. Data were reanalysid using CMA software and results of random model meta-analysis were reported as final results.

The weighted average of heritability for productive traits in dairy cows were between 0.19 and 0.27. Milk protien percentage had the highest (0.27) and milk fat had the lowest (0.19) heritability estimates amonge productive traits. The weighted average of heritability for reproductive traits was in the range of 0.03 to 0.14. Pregnancy period (0.14) had the highest and open days had the lowest (0.03) heritability estimates amonge reproductive traits. The weighted average of genetic correlations of productive and reproductive traits was in the range of -0.56 to 0.88 and the mean weight of the phenotypic correlations of traits was in the range of -0.42 to 0.83. Comparing the results of meta-analysis in present study with the results of individual studies showed that aggregating studies and analyzing by meta-analysis improves the accuracy of the results through reducing standard errors. For example, in studied articles the range of heritability estimates for milk production were between 0.047-0.41, for milk fat were between 0.05-0.56 and for milk protein were between 0-0.7. However, after using meta-analysis method, these ranges were reduced to 0.23-0.25 for milk production, 0.17-0.21 for milk fat and 0.19-0.29 for milk protein. In addition, because of aggregating studies and increasing the amount of data, standard error of estimates in meta-analysis were considerably reduced compared to standard error of estimates in individual studies, especially for productive traits.

Using methods like Meta-analysis will increase the performance of breeding programs and will improve genetic progress of economic traits of animals by gathering all available information, especially for populations with no or not accurate data.

Foot and Mouth Disease is a highly contagious disease of animal that is one of the major barriers to the provision of livestock health and livestock products. This experiment was conducted to investigate the effects of herbal medicines Ashitex and Imion on improving complications of Foot and Mouth Disease, decreasing stress hormones and increasing immune response in sick cows.

In this study, two herbal medicines, Ashitex and Imion, were orally sprayed and to investigate their effects on the improvement of complications of Foot and Mouth Disease, decrease of stress hormones and increase of immune response in cows affected by Foot and Mouth Disease. Ashitex and Imion, were orally sprayed to investigate their effects on improving the complications of Foot and Mouth Disease., reducing stress hormones and enhancing the immune response in cows with Foot and Mouth Disease. Ashitex is a blend of Turmeric, Myrrh, Mazoo and Liquorice, and Imion drug is based on Purple Coneflower. The experiment was performed on 75 cows with Foot and Mouth Disease. To obtain fully practical field results consistent with the cattle storage conditions, no changes were made to the storage conditions, such as feeding, light, temperature and other conditions, and only the cows were blocked and distributed in the prepared boxes. Treatments consisted of: 1-vinegar (control), 2-Ashitex, 3-Ashitex and Imion, 4-Vinegar and Imion, and 5-Vinegar and Ashitex. All treatments were applied for ten days. Ashitex was sprayed 20 ml twice daily. Imion was also given orally to the animal twice daily, 100 ml each time. At the beginning and end of the treatment period, blood samples were taken from the jugular vein of the cows to examine interleukin II gene expression, immune responses, and changes in cortisol and corticosterone hormones.

The second treatment (Ashitex) had the best performance on the appearance and general health of cows with Foot and Mouth Disease. The use of herbal medicine Ashitex improved the appearance and clinical conditions, as well as decreased stress hormones and increased expression of the gene effective in inflammation of cows with Foot and Mouth Disease. Imion also increased the production of immunoglobulin G in cows with previously vaccinated Foot and Mouth Disease and increased the immune response. According to the results of this study, it can be generally concluded that the combination of Turmeric, Licorice, Mazoo and Myrrh, as well as Purple Coneflower and extract and purify them can be effective in the treatment of Foot and Mouth Disease. Reduce, and maybe even retrofit.

According to the results, the use of these two herbal medicines due to their combined effect and faster return to normal status and production cycle than other treatments is recommended to treat Foot and Mouth Disease.

The availability of thousands of polymorphic single nucleotides (SNPs) spread across the genomes made it possible to use genome-wide marker information to predict total breeding value in the implementation of genomic selection. The interaction between several gene loci contributes to the phenotypic changes associated with the expression of complex polygenic traits. The present study aimed to compare the performance of different models with additive and non-additive genetic effects, especially epistasis effects in predicting variance components and genomic breeding values as well as QTN in a dairy cow population based on Bayes Lasso model.

A population of dairy cattle was simulated based on a choice of four pathways to maximize the rate of genetic progress over ten generations with an effective size of 100 individuals in the base population. The genomic structure was assumed consisting of 3 chromosomes with a length of 100 cM and On each chromosome were located 1000 markers 2 allelic markers with a frequency of 0.5. 50 QTL double alleles with equal frequency were randomly assigned to each chromosome. For QTL allelic effects, a gamma distribution with a parameter slope of 0.4 was used in QMSim software and sampling was performed. Phenotypic and genotypic data of the last 10 generations were used for analysis. Marker effects, variance components and genetic parameters were estimated using the Bayes Lasso method in the form of 6 statistical models, that model 1 includes only the marker additive effects, model 2 includes the polygenic effects of animal, model 3 includes the combined effects of additive marker effects and polygenic effects of animal, model 4 includes the dominance effect of markers and polygenic effects of animal, model 5 includes the dominance and additive effects of markers in addition to the polygenic effects of animal, and finally, model 6 includes the additive, dominance and epistatic effects of markers in addition to the polygenic effects of animal. To control the type I error in estimating marker effects, Bonferroni test was used at 1% probability level.

The results of this study showed that the additive model or the polygenic model alone could not show the missing or hidden variance, in such a way that adding non-additive genetic effects including dominance and epistatic effects reduced the residual variance effects. Also in the complete model including additive and non-additive effects, the total genetic variance increased. With the addition of non-additive effects in the statistical model the Hertability in the broad sense was increased and the Hertabilitity in the narrow sense of trait decreased. The accuracy of breeding value estimation in model 1 was the lowest and in models 3 to 6 was the same. Model 5 with the lowest false positive QTN and the highest true positive proportion was the appropriate model for genetic evaluation of the studied traits. By including polygenic and non-additive effects in the model, the number of false positive errors was reduced.

The results of this study showed that the components of additive and dominance variance markers had a small share in the genetic diversity of the studied trait, but the polygenic effects of animal and epistatic had the largest share in the exploring of genetic diversity of trait. The results also showed that the major contribution of gene loci in the exploring of traits is related to additive genes with an additive effect that have a normal distribution. Ignoring non-incremental effects causes inflammation in the additive variance of the trait.

Considering that about 70 to 75 percent (in developed countries about 50-60 percent) of the total production costs related to livestock feed. One of the economical ways of producing is to use waste from agricultural and industrial activities, One of the industrial wastes of corn gluten feed that is used in the feeding of dairy cattle, sheep. A little comparison of performance, Carcass traits and digestibility has done of the same energy and protein feeds in sheep. The aim of this study, was the replacement of Soybean meal with corn gluten feed in the diet of fattening lambs and the investigate effect of it on performance, Carcass traits and digestibility.

This experiment was conducted in a completely randomized design with Four diets (Treatment) containing 0, 33, 66 and 100 percent Corn gluten feed was substituted with soybean meal on fattened lambs. Six lambs were given to each treatment (Repeat) with the age of about three months. Animals were individually located in separate cages for 84 days (15 days adaptation period). The protein and energy content of diets were equal. Dry matter, ash, crude fiber, and crude fat were determined according to AOAC (2000), crude protein was determined by Coldall method (AOAC, 2000), NDF, ADF and by van Sost (1991).

The highest daily feed intake was for lambs fed 100% corn gluten and the lowest daily feed for lambs fed 66% corn gluten (P <0.05). reatments containing 66% corn gluten feed had the highest body weight (P <0.05). In most periods, 66% of corn gluten feed showed the highest weight gain (P <0.05). Feed conversion ratio of lambs receiving 66% corn gluten feed improved in most periods (P <0.05). The digestibility of dry matter, organic matter and protein was 66% higher and significantly different from other treatments (P <0.05). Digestibility of cell wall without hemicellulose (ADF), cell wall (NDF), nonfibrous carbohydrate (NFC) and crude fat digestibility (EE) were not significantly different (P <0.05). There were significant differences among treatments for all carcass composition (P <0.05). The 66% corn gluten level treatment showed the best carcass traits compared to the other treatments. Dry matter, organic matter, crude protein, ash, crude fat, crude fiber, cell wall without hemicellulose and cell wall were 87.96, 82.67, 21.66, 6.33, 3.5, 9.4, 37.55, 12.70.

According to the results mentioned and low-cost corn gluten feed, use of corn gluten feed up to 66% in lambs is recommended.

Grains are typically used as energy-efficient ingredients for high-yielding cows. On the other hand, the use of forage sources in the diet is recommended to improve ruminally fermentation and ultimately maintain health and improve livestock production. Given the contradictory results reported in recent research on the effects of feeding of different sources of grain and forage in dairy cows, we conducted a study aimed at investigating the interaction effects of grain (barley and corn) and forage (alfalfa and corn silage) source in rations on the productive performance of Holstein dairy cows.

Eight Holstein dairy cows (milk production: 46.2 ± 2 kg / day) were used to investigate the interactions between dietary source of grain and forage on productive performance. This experiment was conducted in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement with 4 treatments over 4 periods of 21 days (15 days for dietary adaptation and 6 days for data collection). The first factor was the source of grain used in the diet (barley or corn) and the second factor was the source of forage used (alfalfa or corn silage). Experimental diets were fed as total mixed ration twice daily (7:00, 17:00) and milking was done 4 times daily (4:00, 10:00, 16:00, 22:00). Sampling was performed to collect feed samples and their residues, milk production and composition, rumen fluid, and animal feeding behaviors.

Dry matter intake (23.4 vs. 21.9 kg / day), milk yield (46.9 vs. 44.5 kg / day) and milk fat percentage (3.12 vs. 2.88%) in treatments containing corn grain were more than treatments containing barley grain (P <0.05). Nitrogen uptake was higher in corn-based treatments, but milk nitrogen, an indicator of feed nitrogen utilization efficiency, was lower in these treatments compared to barley grain. The effects of dietary forage source on feed intake and milk production were not significant, but dry alfalfa hay increased the percentage of milk fat compared to corn silage (3.08 vs. 2.92 percent). The use of corn silage forage increased the rumination time and total chewing time as minute per day and minute per kg of dry matter consumed (P <0.05). Although cows consuming corn silage spent more time for eating per kg of dry matter, but cows consuming alfalfa hay consumed more dry matter per meal. Consumption of corn compared to barley tended to increase dry matter intake per meal (P = 0.1). Percentage and amount of milk fat produced as well as fat-corrected milk production had a direct relationship with ruminal pH at three hours after morning feeding (P <0.05).

Although the interaction of main factors in this experiment on functional parameters of dairy cows was not significant, but dry matter intake at each meal when using barley grain in treatments based on corn silage as forage source compared to dry forage Alfalfa was lower but not affected by forage source in treatments based on corn grain. This demonstrates the positive effects of using corn grain in corn silage-based diets to prevent reduced feed intake. Because diets containing corn silage compared to dry alfalfa hay are expected to decrease feed intake due to increased feed particle size as well as higher rumen acidity, however, this higher acidic state will be exacerbated if ground barley grain be used in the diet.

Compensatory growth is the overweight that is achieved by providing the animal with access to adequate food after a period of nutritional restriction. Therefore, a livestock that is affected by a period of feed restriction after re-feeding, especially at the beginning of this period, has less maintenance requirements compared to a livestock that has not been affected by the feed restriction period. Considering the feedlot of 320,000 fattening lambs in Lorestan province per year and the possibility of using feed restriction to promote the use of compensatory growth in lamb fattening, the project was carried out aims to investigate the possibility of process changing the growth rate, fattening and physical and chemical composition of carcass lambs Lori breed by short-term strategies of feed restriction.

Twenty male Lori lambs with a mean live weight of 30±1.45 kg were selected for the experiment. The four experimental diets included 1) the control group (fattening diet without restriction and ad libitum); 2) 80% ad libitum group 3) 70% ad libitum group 4) 60% ad libitum group. At the end of experiment, daily weight gain, final weight, feed conversion ratio, feed efficiency and feed intake were calculated and then three lambs were slathered from each treatment. Carcass characteristics were calculated with the cost of production per kg of weight gain, carcass and lean meat. Percentage of dry matter, ash, crude fat and crude protein were determined for meat chemical composition. Performance data, carcass traits and chemical composition of carcass were completely randomized design with four replications (each replication including six lambs and three for carcass traits and carcass chemical composition) by analysis of covariance means of mixed model procedure. Comparison of mean treatments was performed by Tukey test.

Results showed that there were significant difference between the final weight of lambs at the end of feed restriction period (p < 0.05). At the end of the re-feeding, no significant differences were observed among the control treatment with 70% and 80% feed restriction groups (P>0.05). There were significant difference among intake dry matter of lambs at the end of feed restriction period (p < 0.05). At the end of compensatory growth, no significant difference was observed between control and restraint groups. During the re-feeding period, feed conversion ratio was lower in feed restraint treatments compared to control treatment. Feed efficiency was similar to feed conversion during feed restriction and re-feeding period in the experimental groups. Results of physical composition of carcass during re-feeding showed that the average of most carcass traits in control and 80% of feed restriction treatments had no significant difference and were higher than 70 and 60% of feed restriction. Meanwhile, the fat tail weight and percentage and total carcass fat were higher in the control group than in all control groups. The results showed that the percentage of cold carcass lean meat in the compensatory groups was higher than the control treatment. Percentage of carcass chemicals in feed restriction period showed that dry matter, percentage of crude protein and fat in control treatment were higher than feed restriction treatments and there were significant difference among treatments (P <0.05). The percentage of crude protein in the re-feeding period was higher than the control group.

This study showed that lambs with 80% restriction of feed due to higher weight gain, feed conversion ratio were more favorable in terms of fattening condition than control lambs who consumed feed during whole period. Also, this treatment was the total carcass fat percentage lower and lean meat higher and ultimately, the production costs per kg carcass and lean meat were lower than other treatments.

Chromium (Cr) plays an important role in ruminant’s metabolism. Situations such as accelerating growth, stress and low bioavailability of Cr in feedstuffs, result in depletion of chromium stores of body, therefore, metabolic disorders and growth retardation occurs. Chromium is an essential element for animals and humans It functions as cofactor for insulin and it is assumed to be essential for activation of certain enzymes and stabilization of proteins and nucleic acids Therefore, impaired carbohydrate and protein metabolism, decreased insulin sensitivity in peripheral tissues and thereby decreased weight gain would be expected in Cr-deficient individuals especially under stressful conditions. Chromium improves health by reducing free radicals and also stimulates the immune system and makes the body more resistant to diseases during stress by lowering blood cortisol levels. The aim of this study was to investigate the Effects of chromium-methionine on growth performance, blood parameters and health of Holstein suckling calves under heat stress.

For this experiment, 30 newly-born Holstein calves (average age 1-8 days), average weight 39±1 kg) were used in a completely randomized arrangement with 2 treatments and 15 replications. The experimental treatments were: 1) Basal diet without any additive (control), 2) Basal diet with 0.05mg of chromium-methionine. Daily feed intake were recorded daily and body weight were recorded at birth days, 30, 60 and 65 breeding periods and feed conversion ratio was calculated for each group. The average maximum temperature–humidity index was 91.2 U, indicating severe environmental heat load.

The results showed that the use of chromium methionine supplementation in calves under heat stress had not a significant effect on feed intake, final weight, daily weight gain, feed conversion ratio and skeletal growth during the first, second and entire breeding months. The blood concentration of glutathione peroxidase was affected by chromium methionine supplementation, while the blood concentration of glutathione in calves receiving chromium supplementation was 57.78 versus 47.19 u/g (P <0.04). Respiration rate, breaths/min and heart rate in calves receiving chromium were low, so that numerically the number of breaths and heart rate in chromium-methionine-supplemented calves was 50.50 versus 54.40 per minute and 10 / 98 were in front of 10/50 times. Rectal temperature and fecal score were not affected by chromium intake in calves.

Results of this experiments showed that the use of chromium methionine in suckling calves improved glutathione peroxidase concentration, fecal score and rectal temperature but had no effect on growth performance and skeletal size

High producing ruminants require a significant amount of rumen escape protein. Researches have reported a correlation between increased yield and decreased ruminal degradation of crude protein (CP). Cottonseed is a common feedstuff for ruminants due to its high fiber, energy and protein. But the CP degradability of this ingredient is relatively high in the rumen. Several feed processing methods have been developed to decrease ruminal CP degradation such as heat treatment. The aim of this study was to investigate the effect of heat treatment on chemical composition and rumen degradation kinetics of dry matter (DM) and CP of cottonseed and its effect on Dalagh lambs growth performance.

The cottonseed used in this study was processed for 15 minutes at temperatures of 115 and 125 °C. After processing, dry matter (DM), Ash and organic matter (OM), ether extract (EE), crude protein (CP) and neutral detergent fiber (NDF) were determined according to standard procedures. Degradability trial of DM and CP was done by nylon bag technique using three rumen fistulated male Dalagh sheep. In vitro digestibility and fermentation parameters were determined with batch culture method. Performance trial was performed for 56 days using 18 six- month old Dalagh sheep with a mean weight of 34.75 2 2.69 kg. The lambs were divided into 3 equal groups and each group received one of the diets contained unprocessed cottonseed and heat processed cottonseed at temperatures of 115 and 125 °C. The diets were isocaloric and isonitrogenous. Performance traits including weight gain, feed intake and feed conversion ratio were measured. At the end of experiment, blood samples were taken from sheep to determine the osmotic fragility of red blood cells, blood parameters and hepatic enzymes. Statistical analysis of data from this experiment was performed using SAS (9.1) software and GLM procedure.

Processing had no effect on chemical composition of cottonseed (p < 0.05). Washout fraction, degradation rate of b fraction and effective degradability of DM and CP decreased by heat processing (p < 0.05). The effect of 125 ° C on reducing degradability was greater than that of 115 ° C. So that effective degradability of CP at rumen out flow rates of 2, 5 and 8 percent/h reduced from 84.88, 79.26 and 75.15 percent in control to 83.26, 75.79 and 70.81 percent and 82.32, 73.34 and 67.63 percent in samples processed with 115 and 125 °C respectively. Heat treatment had no effect on in vitro digestibility of dry matter and organic matter, partitioning factor, microbial mass production and its efficiency (P>0.05). But gas yield was decreased (P <0.05) by 125 ° C heat treatment (40.76 ml) compared to control (47.02). Heat processing had no effect on performance traits of animals (P>0.05). However, the daily weight gain in sheep fed heat treated cottonseed was significantly higher than control. Heat treated cottonseed nutrition had no effect on osmotic fragility of red blood cells, blood metabolites and hepatic enzymes.

The results of this study showed that although processing with temperatures of 115 and 125 ° C for 15 minutes reduced the effective degradability of cottonseed in the rumen, but had no effect on blood parameters and performance of lambs. Further research is needed to determine the optimum temperature and duration of application to improve the nutritional value of cotton seed.