JOURNAL OF RUMINANT RESEARCH
Year:2021 | Volume:8 | Issue:4|Papers Count:8

Background and objectives: The accuracy of estimates of variance and covariance components is a prerequisite for designing breeding strategies of important economic traits such as reproductive traits. Genetic grouping was suggested 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 considering genetic grouping for animals with unknown parents. Materials and methods: 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 from 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) was considered the best model. Spearman's rank correlation coefficient was used to examine changes in animal rank by considering the genetic grouping. The accuracy of breeding values and genetic trends were estimated and compared using two models. Data preparation and statistical analysis were performed using R-software and ASReml software, respectively. Results: The amount of variance and the cumulative genetic standard error were lower in model 2 compared to model 1 while it was the opposite for the residual variance, however, there was no significant difference between the values of the two models. Model 2 was selected as the best model for all studied traits based on the goodness of fit criteria. The heritability of CI and CTFS was estimated to be lower (nonsignificant) in model 2 compared to model 1. The heritability values were estimated less than 0. 05 for all reproductive traits within the two models. The ranking of the best males and females changed due to genetic grouping. The accuracy of estimated breeding values (EBVs) for all studied traits was significantly (P <0. 001) higher in model 2 when compared to model 1. The genetic trend of all traits (with the exception of the FSTC in the first and third calving period) was positive in both models 1 and 2, and the estimated values were different between the two models. Conclusion: The results from the current study showed that genetic grouping is necessary to analyze the reproductive traits of Iranian Holstein cows as well as accurately predict the genetic merit of animals.

Background and objectives: Fat is one of the most important nutrients in ruminant nutrition and its fate is effective in the efficiency of feed usage in the gut, especially in the fermentation medium and rumen. It is important to know about the digestibility and energy content of feed ingredients as well as their dry matter degradability, neutral detergent fiber (NDF), and crude protein as measurable nutrients when formulating balanced diets for ruminants. Also, it is important to clearly understand the mechanisms of nutrient degradability and their digestion and absorption while considering the increase in the income of farmers. To study the digestive properties and fermentation kinetics of experimental diets, measuring the gas production was introduced and applied in vitro by incubating feed ingredients within the buffered rumen fluid in late 1970. On the other hand, the nylon bag technique is used to estimate dry matter disappearance, NDF, crude protein, and digestive parameters. In the current study, the effects of different lipid sources on gas production (in vitro), degradability of dry matter, NDF, and crude protein (in sacco) were evaluated within the lipid-containing treatments. Pearson method was applied to evaluate the correlation coefficients of measured parameters. Material and methods: Two experiments were conducted to evaluate the fate and behavior of feed ingredients 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 including 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 in vitro. In the second trial, 4 rumen fistulated Dalagh rams were allotted to measure dry matter, fiber, and crude protein degradability parameters within treatments, using the nylon bag technique. Finally, the Pearson method was used to analyze the results of the correlation between the two experiments. Results: The gas production was higher in the control when compared to the other lipidcontaining treatments at the first 2 h of incubation, while it was not significant at 24 h and it was significant at 96 h within the lipid-containing treatments comparing to the control. Organic matter digestibility, production of short-chain volatile fatty acids, and metabolizable energy in the gas test were significantly higher in the calcium fatty acid treatment than in the control, animal fat and rapeseed oil treatments (P <0. 05). The dry matter degradability of calcium fatty acid treatment was higher than other fat sources within the whole ruminal incubation period (P = 0. 01). The potential for crude protein degradability and fiber degradability were not significantly affected by the different fat sources (P = 0. 07). The degradability of NDF decreased slightly when fat sources were added to the treatments. In this experiment, high correlations were observed in the estimation of biodegradability and prediction parameters of dry matter, crude protein, and NDF in the experimental treatments within the gas test and nylon bag techniques. Conclusion: Results from the current 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 volume of gas at 96 h after incubation within the rumen fluid than that produced by 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 although the incorporation of lipid sources especially protected fat as the energy source has no adverse effect on fermentation, its application also has increased fermentation efficiency. On the other hand, a high correlation was observed between the parameters of the gas test (SCFA, ME, and organic matter digestibility) and the nylon bag technique (a, b and c) using the Pearson method. To conclude, the gas test can be used to evaluate the lipid sources added to the rations with a high efficiency instead of the costly nylon bag technique.

Background and objective: Microsatellites are repetitive regions in DNA including a homogeneous array of mono, di-, tri-, tetra-, penta-, and hexa-nucleotides with a length of less than 1 Kbp which are non-randomly distributed in the genome. The number and density of microsatellites are varying within species even in very close species such as humans and chimpanzees. The frequency of microsatellite motifs and their mutation rate are reported differently in various organisms. Di-nucleotide microsatellites are the most abundant motifs followed by mono and tetra microsatellite motifs in mammalian genomes. Tri-nucleotide microsatellites are more frequent in plants. However, the effect of different microsatellite motifs on genetic diversity or population structural parameters is a topic that has received less attention. Material and methods: In the present study, using the 36 VCf file of microsatellite markers extracted from the 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 the north-west part of Iran and Ovis orientalis samples belongs to the central part and north-west of Iran. After rearrangement and filtration on the data file using Samtools and VCFtools software, we classified the whole markers on four different motif types including di-tri-and tetra-nucleotide microsatellites and a file include 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 an 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). Results: Estimation of all six parameters revealed various results using a 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 values 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 cases where the implication of the model showed significant results, Tukey Honestly Significant Difference test was used to test pairwise contrasts between different subsets. Conclusion: Our results propose 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.

Background and objective: The high levels of concentrate are used to increase gaining in fattening Sheep. This results in Acidosis, Liver abscess, and Bloat which produce some problems. Using rumen modifiers can help to prevent these disorders. This study aimed to evaluate the effects of dietary supplementation of malate (Rumalato), maltodextrin, and mixture malate-maltodextrin on Sheep performance parameters, Rumen fermentable products, and blood metabolites of lambs fed high-concentrate growing diets. Materials and Methods: 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 maltodextrin, 3) basal diet plus 15 gr malate (Rumalato), and; 4) basal diet mixture of 15 gr malate plus 30 gr maltodextrin. Dry matter intake, Bodyweight gain, and Rumen fluid were 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 carried out before morning feeding. Blood parameters were defined at the end of the experiment for Glucose, Albumin, Cholesterol, and Blood urea nitrogen. Results: 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). Bodyweight gain and feed conversion ratio showed no significant difference at the end of the experiment (P>0. 05). However, the average body weight gain showed a tendency towards an increase in lambs fed malate-maltodextrin. The level of 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 the control (63. 8 mg/dl) and malate (65 mg/dl) (P=0. 04). Other blood parameters had no significant difference. Among the rumen parameters, pH level tended to increase in the lambs fed maltodextrin and malate-maltodextrin compared to other treatments, however, with no significant difference (7. 1 and 6. 9 to 6. 8) (P>0. 05). Other parameters of rumen fluid such as volatile fatty acids had no significant difference between treatments. Conclusion: To conclude, results of this study showed that adding of maltodextrin and mixture malate-maltodextrin can improve dry matter intake in fattening sheep and this is effective for body weight gain and feed conversion ratio. However, rumen modifiers are effective for rumen pH and in the prevention of low pH, therefore, result in the balanced production of rumen fermentable products.

Background and objective: 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. Materials and Methods: Growth curve parameters were estimated using the Brody model and data of 27537 Ghezel sheep. This population pedigree was checked by pedigree viewer software and the two families were selected for this project. To do the present research two half-sib families, 51 offspring of two genera of sheep breeding in the Ghezel Miandoab Breeding station 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. DNA extraction was performed from the whole blood using chloroform and isoamyl-alcohol methods and 4% metaphor agarose gel was used for multiplication of microsatellite sites using Touchdown PCR. 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 for the QTL analysis was to identify the relationship between genetic markers and QTLs by two markers. Results: 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). Conclusions: No significant differences were found in the QTL analysis. However, 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.

Backgrounds and objective: The use of growth promoters and the strengthening of the immune system has been one of the concerns among the livestock nutritionists. At first, using antibiotics was the best solution; however, concerns about their effects on livestock products have prompted scientists to find suitable alternatives. Probiotics as natural products along with some vitamins were good choices. This study was conducted to investigate the effects of probiotics and vitamin E+selenium supplements on the performance and some blood and ruminal parameters of Holstein calves. Material and Methods: Twenty-four Holstein male calves were randomly assigned to 4 treatments after weighing and postpartum procedures. 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 an injectable supplement of vitamin E+ selenium (0. 14 ml per kg live weight), and 4-basal diet with probiotic and vitamin E + selenium. Probiotics were administered daily and vitamin E+ selenium at birth and 14 days of age. The calves were fed milk twice a day. The calves were also fed with a starter formula 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. Feed intake was calculated daily. Skeletal growth indices including body length, withers height, hip height, hip width, and heart girth were measured and recorded at the beginning and then on days 14, 28, 42, and 56 of the experiment. Blood sampling was done at 7, 21, 42, and 56 days old calves, four hours after morning feeding by venoject tubes via the 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 to measure ammoniacal nitrogen and determine the fatty acids profile. The data analysis were carried out in SAS software using the MIXED procedure. Results: Probiotic and Vitamin E + selenium did not have any significant effect on the 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 recipients of vitamin E + selenium. 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), other blood parameters were not affected by treatments (P>0. 05). Probiotic, vitamin E+selenium and their combination reduced blood protein level compared to the control. In contrast, these treatments increased IgG level. Treatments had no effects on the concentration of volatile fatty acids (P>0. 05). However, the use of probiotics and vitamin E + selenium increased the amount of acetate and propionate numerically. The amount of ammonia nitrogen and pH were not affected by the treatments (P>0. 05). Conclusion: Probiotic treatment improved feed conversion ratio (FCR) and increased some skeletal growth indices in suckling calves. The use of probiotics, vitamin E + selenium, and their combination increased the absorption of IgG, which may lead to resistance of calves to infectious diseases such as diarrhea.

Background and objectives: Red meat is one of the strategic foods to meet the increasing requirements of human populations to high quality protein. Therefore, this study aimed to compare growth performance, carcass characteristics, and economic profits between Holstein-Belgian Blue cross and pure Holstein calves. Material and methods: This study was carried out in the Mahdasht Milk and Meat farm, Dasht-e Naz Agriculture Company near Sari (Mazandaran, Iran). The performance of 24 calves of each breed (48 calves in total) was compared in a fattening period of 7 months. The average weight and age of calves at the start of the experiment were 258. 21 and 274. 95 kg; 321 and 313 d, respectively. Feed intake was measured daily for each group. A total mixed ration was delivered to the experimental animals twice a day at 0800 and 1600 h. Animals weighted monthly to obtain average daily gain. Statistical analyses were performed using SAS software (GLM and MIXED procedures). Results: The results indicated that average daily gain was significantly higher in crossbred calves than in pure-bred Holstein calves (1. 43 vs 1. 33 kg). The pure-bred Holstein calves had significantly lower dry matter intake than Belgian Blue crossbred calves. However, feed conversion ratio was no significant in Belgian Blue crossbred calves when compared to the Holstein group (6. 74 vs 7. 04). the dressing percentage for BB×H crossbred was higher than for pure Holstein. The effect of genetic groups was not significant on the thickness of the fat covering the back, through the front, and back hindquarters. However, the thickness of the fat covering loin was significantly different between genetic groups (P<0. 05). Weights of internal organs (i. e., kidneys, liver, and heart) were significantly higher in pure Holstein calves than those in crossbred cattle. Also, fat depots weight (subcutaneous and visceral) was significantly highest in pure Holstein and lowest in Belgian Blue crossbred calves (P<0. 05). Conclusions: Economic calculations demonstrated that the respective highest profit for the whole fattening period belonged to crossbreds 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 was substantiated.

Background and objective: The future of any dairy farm depends on the success of the female calf rearing. In recent years, new aspects of the use of forage in the starter feed have been discussed. Studies have reported that a starter diet lacking forage will lead to the development of abnormally shaped villi in the rumen of calves. This will negatively affect rumen growth and development. However, nowadays there are different opinions about the use of forages in the starter feed for suckling dairy calves so that some researchers believe that the presence of forages in the starter feed reduces the performance of dairy calves. In the current study, the effect of 15% alfalfa forage level in the ground starter diet was investigated on functional responses and skeletal growth traits of dairy calves fed a step-down milk feeding procedure. Materials and methods: 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), and 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). Results: The results of this study showed that adding 15% alfalfa hay to the starter feed did not have a significant effect on the average daily weight gain, feed efficiency, and skeletal growth traits of suckling 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 while propionate concentration was higher for the control treatment (P<0. 05). Rumen pH also tended to increase in calves consuming forage. Conclusion: Feeding 15% alfalfa forage mixed with the ground starter feed improved feed intake of calves 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.