مجله پژوهش در نشخوار کنندگان
سال هشتم شماره 4 (زمستان 1399)

The estimate variance components with a satisfying accuracy of important economic traits such as reproductive traits is a prerequisite for designing breeding strategies. Genetic grouping was suggested in order to predict breeding values of phenotypic records in different years with high accuracy. As there is unknown information in the pedigree of Holstein dairy cows in Iran, genetic group animal models with unknown parents seem necessary. Therefore, the present study was conducted to estimate the genetic parameters, genetic trend and accuracy of estimated breeding values of some reproductive traits (i.e. calving to first service (CTFS), first service to conception (FSTC) and calving interval (CI)) in dairy cows with considering genetic grouping for animals with unknown parents.

Information on calving and insemination dates of the first three calving periods from 3361 herds of the Iranian Holstein, collected by the Animal Breeding Center of Iran during 1981 to 2013 was used. Animals with unknown parents were grouped based on the year of birth and sex and the traits were analyzed using two models, with (model 2) or without genetic grouping (model 1). The model with the lowest Bayesian information criterion (BIC) and the Akaic information criterion (AIC) is considered the best model. Spearman's rank correlation coefficient was used to change in animal rank by considering the genetic grouping. The accuracy of estimated breeding values and genetic trend of the traits was estimated using two models and was compared. Preparation of data for statistical and genetic analysis were carried out using R-software and ASReml software, respectively.

The amount of variance and the standard error of additive variance in model 2 was lower than model 1 and for the residual variance was conversely, but there was no significant difference between the values of the two models. Model 2 was selected the best model for all studied traits based on the goodness of fit criteria. Heritability of CI and CTFS using model 2 was estimated lower (non-significant) than model 1. The heritability value for all reproductive traits was estimated less than 0.05 by two models. The rank of males and females changed duo to genetic grouping. The accuracy of estimated breeding values (EBVs) for all studied traits in model 2 was significantly higher than model 1 (P <0.001). The genetic trend of all traits (exception of the FSTC in the first and third calving period) was positive by model 1 and 2, and the estimated values between the two models were different.

The results of the current study showed that using genetic grouping for reproductive traits analysis of Iranian Holstein cows and accurate prediction of genetic merit of animals seems necessary.

Fat is one of the most important nutrients in ruminant’s nutrition and its fate in the fermentation medium and rumen, is effective in the efficiency of feed usage. Awareness of digestibility and energy production of feeds and determine degradability of dry matter, neutral detergent fiber (NDF) and crude protein as a measurable nutrient, is valuable for formulating of balanced rations and correct understanding of degradability mechanism, digestion and uptake of nutrient for increase efficiency and income of farmers. In last of 1970 measure of gas production via incubation of feeds in buffered rumen liquid for assaying of digestibility properties of diets and fermentation kinetics were started with in vitro method. Whereas disappearance of dry matter, NDF predicted with nylon bag technique. In this experiment effect of different source of lipid on gas production (in vitro), dry matter, NDF and crud protein degradability (in Sacco) were assayed. Correlation coefficients of two experiment parameter were analyzed with Pearson method.

Two experiments were conducted to assess the fate and behavior of feed and the kinetics of digestion of three fat sources. In the first experiment, the amount of gas production from the digestion of four experimental treatments include : 1) no added lipid source (control) and 2, 3 and 4) with 5% calcium fatty acid, animal fat and rapeseed oil, respectively, incubated in rumen fluid, was measured with in vitro method. In the second trial 4 rumen fistulated Dalagh rams were allotted for measuring degradability parameters. In the second experiment, rumen fistulae male sheep were used to determine the biodegradability components of dry matter, fiber and crude protein in the above treatments by nylon bag method. Finally, the results of correlation between the two experiments were analyzed by Pearson method.

Gas production at the first 2 h of incubation was higher than other the lipid content treatments, not significant at 24 h and was significant at 96 h in the lipid source treatments than the control treatment. Organic matter digestibility, short chain volatile fatty acids production, and metabolizable energy in the gas test were significantly higher in the calcium fatty acid treatment than control, animal fat and rapeseed oil treatments (P <0.05). The dry matter degradability of calcium fatty acid treatment was more than other fat sources (P = 0.01). Crude protein degradability potential and fiber degradability were not significantly affected by different fat sources (P = 0.07). Degradability of NDF decreased slightly by adding fat sources. In this experiment, high correlations were observed in estimation of biodegradability and prediction parameters of dry matter, crude protein and NDF in experimental treatment in gas test and nylon bag technique.

Results of this study showed that gas production and biodegradability were different in treatments containing lipid sources. Diets containing protected fat with higher digestibility, produced more short chain fatty acids, higher metabolizable energy, and greater gas at 96 h after incubation in rumen fluid than animal fat and vegetable oil containing treatments. The highest effective degradability was observed at 5% flow level for dry matter, crude protein and NDF. All of these results indicate that incorporation of energy source with lipid sources especially protected fat has no adverse effect on fermentation and its use has increased fermentation efficiency. On the other hand, a high correlation was observed between the parameters of gas test (SCFA, ME and organic matter digestibility) and nylon bag technique (a, b and c) with Pearson method. Furthermore, gas test can be used with high efficiency to evaluate the lipid source added rations be instead of the costly method of nylon bag technique.

Microsatellites are repetitive regions in DNA including homogeneous array of mono, di, tri, tetra, penta and hexa nucleotides with length of less than 1 Kbp which are non-randomly distributed in genome. The number and density of microsatellites is vary within species even in very close spices such as humans and chimpanzees. The frequency of microsatellite motifs and their mutation rate is reported differently in various organisms. In mammalian genomes di-nucleotide microsatellites are the more abundant type following by mono and tetra microsatellite motifs as next. Tri microsatellites are more frequent in plants. However, the effect of variety in microsatellite motifs on genetic diversity or population structural parameters is a topic that has received less attention.

In the present study with using the 36 VCf file of microsatellite markers extracted from whole genome of Iranian sheep “Ovis aries and Ovis orientalis” by NGS, the total number of 163973 microsatellite markers were detected. The distribution of Ovis aries samples is from north-west part of Iran and ovis orientalis samples are belongs to central part and north-west of Iran. After rearrangement and filtration on data file using Samtools and VCFtools softwares, we classified the whole markers on four different motif types including di- tri- and tetra-nucleotide microsatellites and a file includes all three microsatellite types. Several subsets including 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 400 and 500 markers were generated from each microsatellite motif types using a R script. Six common genetic diversity parameters including observed and expected heterozygosity, Nei diversity index, Shanon index, Allelic richness and FIS were calculated for each different subset of number and motif type of microsatellites in MSA (V.4.05) software. 10 replications were considered for each parameter. The mean and variance were calculated among 10 replications and results were represented by boxplots using R (v.3.3.3). The statistical investigation of parameter estimation differences using different microsatellite number and motif types were analyzed using ANOVA for testing the hypothesis of equality of means in R (v.3.3.3).

Estimation of all six parameters revealed various results using different number of loci as well as motif types. Additionally, the results revealed higher values for parameters estimated with di microsatellite motifs compared to others. In addition, the highest and lowest value for most parameters were obtained by 40-di and 10-tri/tetra microsatellites respectively. The statistical significance on findings of parameter values using different number/motif of microsatellite markers were analyzed using ANOVA in R (v.3.3.3). In the case with significant results, Tukey Honestly Significant Difference test was used to test pairwise contrasts between different subsets.

Our result proposes a better application of di microsatellites for genetic diversity studies in sheep populations. Moreover, results showed that for stable estimation of population parameters in genetic diversity studies a minimum of 50 microsatellite loci are needed.

The high levels of concentrate are used for increase gaining in fattening Sheep. This can be caused Acidosis, Liver abscess and Bloat which produce some problems. Using of rumen modifiers can help to prevent of this disorders. The aim of this study was to evaluate the effects of dietary supplementation of malat (Rumalato), maltodextrin and mixture malate-maltodextrin on Sheep performance parameters, Rumen fermentable products and blood metabolites of lambs fed high-concentrate growing diets.

For this purpose, 48 Shall lambs (46.1± 4.1 kg body weight) were randomly assigned to four dietary treatments in a completely randomized design with 12 lambs per treatment for 30 days. The treatment groups were as follows: 1) control: basal diet without any additive, 2) basal diet plus 30 gr maltodextin, 3) basal diet plus 15 gr malate (Rumalato) and; 4) basal diet mixture of 15 gr malate plus 30 gr maltodextrin. Dry matter intake, Body weight gain, Rumen fluid was collected 3-5 hours after morning feeding. Rumen parameters were measured for pH and volatile fatty acid at the end of the experiment. Blood sampling was collected before morning feeding. Blood parameters were defined at the end of experiment for Glucose, Albumin, Cholesterol and Blood urea nitrogen.

Dry matter intake was higher (p < 0.05) in lambs fed maltodextrin (1.86 kg/d) and mixture malate-maltodextrin (1.87 kg/d) than in lambs fed control (1.79 kg/d) or malate diet (1.80 kg/d) (P=0.03). Body weight gain and feed conversion ratio had not significant difference at the end of experiment (P>0.05). But average body weight gain showed tended to increase in lambs fed malate-maltodextrin. The blood glucose was significant between treatments and it was 79 mg/dl in lambs fed maltodextrin and 78 mg/dl in malate-maltodextrin compared to control (63.8 mg/dl) and malate (65 mg/dl) (P=0.04). Other blood parameters had not different. Among of rumen parameters, pH tended to increase in the lambs fed maltodextrin and malate-maltodexrtin compared to other treatments but without significant difference (7.1 and 6.9 to 6.8)(P>0.05). Other rumen fluid parameters such as volatile fatty acids had not significant difference between treatments.

Totally, results of this study showed that adding of maltodextrin and mixture malate-maltodextrin can be improved dry matter intake in fattening sheep and this is effective for body weight gain and feed conversion ratio. However rumen modifiers are effective to rumen pH and prevention of low pH and caused balance in production of rumen fermentable products.

One of the disadvantages of estimating genetic parameters based on the absolute weight of sheep at a given age is that some genes affect growth only in a specific period of animal life. There are also pleiotropic effects between weight cross-sectional traits of different ages. Therefore, that selection for one trait causes a correlated response in other traits. So focusing on all the stages of the growth curve and the components that characterize the curve can produce more genetic progress. Research results show that growth curve variables are heritable in different species. Therefore, it is possible to modify the growth curve through selection. Understanding the genetic and environmental relationships between different weights, maturity and growth rates at all stages of development is essential for designing a breeding program to improve production efficiency over the lifetime of the animal. Therefore, identifying and locating QTLs controlling growth curve parameters as heritable traits could be a useful research scenario for investigation. Ultimately, it will increase meat production.

Growth curve parameters were estimated using the Brody model and data of 27537 Ghezel sheep. These population pedigree checked by software pedigree viewer and the two families were selected for this project To do present research two half-sib family, 51 offspring of two genera of sheep breeding in the Ghezel Miandoab Breeding station of were taken. The chromosomal positions were located on 2 and 5 of the microsatellite were used to determine the genotype. The marker spacing on the chromosomal map was under 30CM. The DNA extraction was performed using Sammady Shams and colleagues from the whole blood and 4% metaphor agarose gel was used for multiplication of microsatellite sites using Touchdown PCR and. UVDOC software was used to score bands. Descriptive statistics were calculated for molecular indices of each markers locus using POPGENE software. Upon completion of genotyping three files map, genotype and records phenotype were prepared and then evaluated normality raw data and correction for fixed effects (gender, type of birth,) by the procedure GLM in SAS 9.2 software made in 2015 was carried out. The analysis results microsatellites showed that polymorphism fit there, but alleles heterozygous rams similarity high, suggesting consanguinity with alleles of the sheep show. The method used to The QTL analysis was identified the relationship between genetic markers and QTLs by two markers.

The results of microsatellite analysis showed that there is a good polymorphism in the studied population. Finally, the results of the two families indicated no significant QTL identification on chromosomes 2 and 5 for traits of brody growth curves parameters (A, B, C).

No significant differences were found in the QTL analysis. Of course, the plan was criticized because of the low number of markers, the number of families and each family member. These factors may, in turn, be the reason for the lack of QTL identification in this design.

The use of growth promoters and the strengthening of the immune system has been one of the concerns of livestock nutritionists. At first, using antibiotics was the best solution. But worries about their effects on livestock products have prompted scientists to find suitable alternatives. Probiotics as a natural product, along with some vitamins, were a good option. This study was conducted to investigate the effects of probiotic and vitamin E+ selenium supplements on performance and some blood and ruminal parameters of Holstein calves.

Twenty-four Holstein male calves were randomly assigned to 4 treatments after weightlifting and prenatal follow-up. The calves were transferred to individual cages and fed a sufficient amount of colostrum for the first 3 days. Treatments included: 1- basal diet (starter diet + milk), 2- basal diet with Bioguil probiotic (2 g), 3- basal diet with injectable supplement of vitamin E+ selenium (0.14 ml per kg live weight), and 4- basal diet with probiotic and vitmin E + selenium. Probiotics were given daily and vitamin E+ selenium at birth and 14 days of age. The calves were fed milk twice a day. The starter was also given to them from the beginning of the second week of the experiment. The calves were weighed at the beginning of the experiment as well as once every two weeks. The amount of feed intake was calculated daily. Skeletal growth indices including body length, withers height, hip height, hip width, and heart girth were measured and recorded on the days of entering the experiment, 14, 28, 42, and 56. At 7, 21, 42 and 56 days old, blood sampling was done four hours after morning feeding by venoject tubes via jugular vein. Blood metabolites including glucose, albumin, total protein, beta hydroxyl butyric acid, cholesterol, triglyceride, urea and immunoglobulin G (IgG) were measured. The rumen fluid was collected using an esophageal catheter on days 21, 42, and 60 days to measure ammoniacal nitrogen and determine the fatty acids profile. The data were analyzed using SAS software according to MIXED procedure.

Probiotic and Vitamin E + selenium did not have any significant effect on weight gain and feed intake of calves (P >0.05). However, in calves receiving probiotic and probiotic combination with vitamin E + selenium, despite the lower initial weight, total and daily weight gain was numerically higher than control and those recipient vitamin E + selenium. The amount of feed conversion ratio (FCR) in the probiotic treatment showed a tendency to improve compared to the control (P = 0.09). Except for total protein (P= 0.002) and IgG (P=0.0004), the other blood parameters were not affected by treatments (P>0.05). Probiotic, vitamin E+ selenium and their combination reduced blood protein level compared to control. In contrast, these treatments increased IgG level. Treatments had no any effect on volatile fatty acid concentration (P>0.05). However, the use of probiotics and vitamin E + selenium increased the amount of acetate and propionate numerically. The amount of ammoniacal nitrogen and pH were not affected by the treatments (P>0.05).

Probiotic treatment improved feed conversion ratio (FCR) and increased some skeletal growth indices in dairy calves. The use of probiotics, vitamin E + selenium and their combination increased the absorption of IgG, which can lead to calf resistance to infectious diseases such as diarrhea.

The aim of this study was to compare growth performance, carcass characteristics , and economic profits between Holstein -Belgian Blue cross and pure Holstein calves .

This study was carried out in the Mahdasht Milk and Meat farm , Dasht -e Naz Agriculture Company (Sari - Mazandaran ) , affiliated to Mostazafan Foundation of the Islamic Revolution , Iran . Beef crosses were produced by crossing Holstein (H) cows with Belgian Blue (BB ) bull’s semen . The performance of 25 calves of each breed ( 50 calves in total ) was compared in a fattening period of 7 months . Feed intake was measured daily for each group using a residual feed intake ( RFI ) system. Total Mixed Ration ( TMR ) diet was delivered to the animals at 8 o'clock in the morning and at 4 o'clock in the afternoon . Animals weighted monthly in order to obtain average daily gain. Statistical analyses were performed using SAS programs ( GLM and MIXED procedures ) .

The results indicated that average daily gain was significantly higher in Holstein - Belgian Blue cross calves than in pure Holstein calves (1.43 vs 1.33 kg ) . The pure Holstein calves had significantly lower dry matter intake than Belgian Blue crossbred . However, feed conversion ratio in the BB×H calves was remarkably more favorable than Holstein group (6.74 vs 7.04) . Dressing percentage for BB×H crossbred was higher than for pure Holstein . Effect of genetic groups on fat thickness through the front hindquarter, thickness of the fat covering over the back and thickness of the fat through the front hindquarter was not significant. Hovewer, thickness of the fat covering over the loin was significantly different among genetic groups (p < 0.05) . The comparisons of the least square means across genetic groups showed that smaller internal organs (e.g. liver) in Belgian Blue crossbred and largest in pure Holstein . Also, fat depots weight (subcutaneous and visceral) was significantly highest in pure Holstein and lowest in Belgian Blue crossbred (p < 0.05) .

Economic calculations demonstrated that the respective highest profit for the whole fattening period belonged to crossbred of BB×H (38543843 Rials ) , and pure Holsteins (24826300 Rials ) . Therefore, the hypothesis that the calves from Holstein - beef crosses have higher economic productivity than pure Holstein calves is confirmed .

The future of any dairy farm depends on the success of the female calf rearing. In recent years, new aspects the use of forage in the starter feed has been discussed. Studies have reported that a starter without forage leads to the development of abnormally shaped villi in the calf's rumen, which will negatively affect rumen growth and development. However, today there are different opinions about the use of forages in the starter feed for dairy calves so that some researchers believe that the presence of forages in the starter feed reduces the performance of dairy calves. In this study, the effect of 15% alfalfa forage level in the ground starter diet on functional responses and skeletal growth traits of dairy calves fed a step-down milk feeding procedure was investigated.

The experiment was designed and conducted in a completely randomized design using 30 Holstein female calves (15 calves per treatment). Experimental treatments were as follows: 1- ground starter diet without forage (control) 2- ground starter diet consisted of 15% alfalfa hay. The milk feeding pattern was the same for both treatments and was a step-down procedure as 2 times per day(6 liters to 30 days, 4 liters to 45 days, and 2 liters to 56 days). All calves were weaned on day 56 of the experiment and keep until day 70 in the experiment. Feed intake and weight gain were measured and recorded weekly. Skeletal growth traits were measured on days 1, 56, and 70 of the experiment. Rumen fluid was measured on day 60 of the experiment. Statistical analysis was performed using the Mixed procedure as repeated measures for 3 periods (before weaning, after weaning, and the whole period).

The results of this study showed that adding 15% alfalfa hay to the starter feed did not have a significant effect on the mean daily weight gain, feed efficiency, and skeletal growth traits of dairy calves. Calves that received the forage treatment had higher starter feed intake in the post-weaning period than the starter diet without forage (P <0.05). Acetate concentration was higher for 15% forage and propionate concentration was higher for the control treatment (P <0.05). Rumen pH also tended to increase in calves consuming forage.

Feeding 15% of alfalfa forage mixed with the ground starter feed improved their feed intake after weaning. These results indicate that the use of alfalfa forage in the ground starter diet reduces the stress of weaning and improves rumen development.