JOURNAL OF RUMINANT RESEARCH
Year:2020 | Volume:7 | Issue:4 |Papers Count:8

Background and objectives: The in vitro gas production test (IVGP) is used for evaluating the nutritional value of feedstuffs in animal nutrition. In IVGP, the volume of gas produced during incubation time is fitted by using a nonlinear model and some parameters related to ruminal fermentation kinetic are predicted. Over the past years, animal nutrition researchers have proposed a variety nonlinear models for this purpose. However, it has been reported that each of these models have predicted ruminal fermentation parameters with different accuracy and presented contradictory results. The purpose of this experiment was to compare the accuracy of some nonlinear models for predicting of gas production kinetics in different diets. Materials and methods: For this experiment, five diets with different forage to concentrate ratio (70: 30, 60: 40, 50: 50, 40: 60 and 30: 70) were prepared. Feedstuffs which used for preparing of these diets included alfalfa hay, wheat straw, barley grain, wheat bran and soybean meal. For investigating the ruminal fermentation kinetic of the experimental diets, the IVGP was used in three separate runs. For each run, rumen fluid was obtained from three fistulated Mehraban rams before the morning feeding. Then, 200 mg of each dried experimental diets with 30 ml of buffered rumen fluid were transferred into each glass vial (in three replications) and all vials were capped. The prepared vials (three vials were considered as the blanks) were incubated at 39 ° C and the volume of gas produced were recorded at 2, 4, 6, 8, 10, 12, 16, 20, 24, 36, 48, 72, 96, 120, 144 hours after incubation. The results (the volume of gas produced at different incubation times) were fitted for exponential (EXP), exponential with lag time (EXPL), Mitscherling (MIT), Korkmaz-Uckardes (KOR) and Weibull (WEB) models. The models goodness of fit were performed using mean square error (MSE), coefficient of determination (R2), residual mean absolute deviation (RMAD), mean percentage error (MPE) and relative efficiency (RE). Durbin-Watson (DW) test and Akaike's information criterions (AIC) were used for selection of the best model. Results: Results showed that the models had no significant difference in term of asymptotic gas volume (A). The EXP model had the highest MSE (35. 74), RMAD (4. 67), MPE (4. 46) and lowest R2 (0. 970), (P < 0. 05). The lowest MSE (2. 63) and RMAD (1. 13) were observed in the WEB model (P < 0. 05). The RE of the WEB model was higher than the other models. The highest (56. 18) and lowest (23. 29) AIC values were observed in the EXP and WEB models, respectively. The DW value in the EXP, EXPL, MIT, KOR and WEB models were 0. 260, 1. 187, 1. 187, 0. 955 and 1. 653, respectively. Conclusion: Generally, results showed that the EXP model predicted gas production kinetic of the tested diets less accurately and the WEB model had the highest accuracy.

Background and objectives: Many prominent traits in livestock including disease resistance and dystocia, present a classification distribution of phenotypes. These traits are important in animal breeding due to importance of animal welfare and human tendency for healthy and high quality products. Therefore, identifying and characterizing the genetic variants that impact threshold traits, ranging from disease susceptibility, is one of the central objectives of animal genetics. In this regard, genomic selection can have an important role in increasing the genetic progress of the threshold traits. The objective of current study was genomic evaluation of area under receiver operating characteristic curve (AUROC) of support vector machine (SVM), GBLUP and Bayes LASSO methods for different rates of binary phenotype distribution in training set. Materials and methods: A population of 1000 animals genotyped for 10, 000 markers was simulated using QMSim software. Genomic population were simulated to reflect variations in heritability (0. 05 and 0. 2), number of QTL (100 and 1000) and linkage disequilibrium (low and high) for 29 chromosomes. In order to create different rates of discrete phenotype, the animal’ s phenotype of training set was coded as 1 (inappropriate phenotype) depending on whether their phenotype residuals was less than the average of residuals ( ),-1 or + 1 for the first, second and third approaches, respectively, and other individuals was defined as code 0 (appropriate phenotype). Three statistical models were implemented to analyze the simulated data including SVM, GBLUP and Bayes LASSO methods. Results: Optimal training sets were characterized by inappropriate phenotype rate that were similar to the population real, leading to the highest AUROC in SVM, GBLUP and Bayes LASSO methods, in which concluded for-1 threshold point to the training set. The highest (0. 813)and lowest(0. 521) AUROC were observed for SVM method. Generally, heritability of trait was a factor affecting on genomic AUROC of SVM, GBLUP and Bayes LASSO methods; so that we recognized an increase in genomic AUROC with increase in heritability in all three statistical methods. Average r2 in the low and high LD scenarios was 0. 221 and 0. 435 at distances of 0. 05 cM and the results showed an increase in genomic AUROC using GBLUP, Bayes LASOO and SVM methods with increasing in linkage disequilibrium. The result of current study showed that high level of LD between SNP and QTLs increased the probability of adjacent markers sampling for re-sampling methods. Therefore, this resulted in a positive performance of SVM. Despite of the higher AUROC of GBLUP and Bayes LASSO methods at different scenarios, SVM method showed a better performance when discrete traits were controlled by a large number of QTLs. Conclusions: Despite the important role of different rates of binary phenotype distribution in training set, SVM method to predict genomic AUROC of discrete traits depends on genetic basis of the population analyzed and cost parameter.

Background and objectives: Some reports indicate that, due to different reasons, in grazing animals (such as nomad animals) nutrients deficiency may occur particularly for degradable and undegradable protein, metabolizable energy, vitamins and some minerals including sulfur and phosphorus. Thus, in some parts of the world, supplemental nutrients in the form of supplemental blocks are used in animal nutrition to overcome these deficiencies and to improve the nutritional value of consumed feeds. Application of supplemental blocks has been highly extended in recent years. The current study was designed and conducted to investigate the effects of supplemental block containing urea, molasses and mineral-vitamins on productive and reproductive performance of Qashqai ewes, in Fars province. Materials and methods: For conducting the experiment, a total number of 75 Qashqai ewes (1-4 parity) were chosen and assigned into three experimental groups (treatments) (25 replicates per treatment). All groups were fed with pasture forage as main feedstuff throughout the study. In the control group, ewes did not receive supplemental block but in two other groups, they received 100 g (T100) or 150 g (T150) block/ewe/day, in two phases (The first phase 20 days before breeding until 50 days after that and the second one 30 days before expected lambing until lamb weaning at 90 days of age). The supplemental block contained the following ingredients: molasses, urea, wheat bran, common salt, mineral-vitamin supplement, gypsum, cement and sodium bicarbonate. Results: The results indicated that feeding ewes with 100 or 150 g supplemental block resulted in a significant decrease in percentage of the barren ewes (P < 0. 05). Lambing rate of ewes in T100 and T150 groups significantly increased compared to the control group (P < 0. 05). The findings indicated that Lamb birth weight, lamb average daily gain, weaning weight of lambs at 90 days of age as well as the number of lambs weaned per 100 ewes and live weaned lamb per ewe were significantly higher in two supplemented groups than the control group (P < 0. 05). Twinning rate and percentage of lamb mortality were not influenced by experimental treatments (P > 0. 05). Conclusion: In conclusion, findings of the current study indicate that feeding ewes with 100 grams supplemental block containing urea, molasses and mineral vitamins under Qashqai nomad condition can improve their productive and reproductive performance (lambing rate, lamb birth weight, average daily gain and weaning weight at 90 days of age) and therefore, using this nutritional strategy could be recommended.

Background and objectives: Iran is the main habitat of many forage and medicinal species with good nutritional value. They grow under harsh environmental conditions such as low rainfall and drought and can be a good alternative to some common forage items such as alfalfa that often require very favorable conditions for their growth. The present study was to determine the appropriate level of replacement of purslane in the diet and its effect on the digestive and fermentative activity of microbial population, microorganisms isolated from rumen of lambs fed experimental diets. Materials and methods: Experimental treatments included control diet (no purslane supplement) and four diets containing levels of 25, 50, 75 and 100% purslane alfalfa. The gas production test was used to determine the appropriate replacement level. The amount of gas produced in the samples was recorded at 2, 4, 6, 8, 10, 12, 24, 48, 72 and 96 hours after incubation and the parameters of gas production, organic matter digestibility and metabolic energy were estimated. The digestibility of dry matter and organic matter was investigated under specific culture conditions of microorganisms. At this stage, the diets containing (0, 25, 50%) of the purslane plant selected from the experiment were tested with rumen of lambs fed the diets containing these treatments. The data were analyzed using a completely randomized design. Results: The results of this study showed that the level of 100% purslane replaced by alfalfa had the highest amount of gas production (25. 80 ml) compared to other experimental diets and its difference with 25 and 50 % levels was not (P > 0. 05). Fermentable fraction was higher in all levels of purslane and was significantly higher than control (P < 0. 05). Organic matter digestibility was also significantly higher at 50, 75 and 100% levels than other treatments (P < 0. 05). The highest amount of microbial crude production was observed in 50 (77. 2), 75 (78. 5) and 100 (79. 1) percent treatments and showed significant differences with other treatments (P < 0. 05). No significant difference was found between ammonia nitrogen and pH of experimental diets incubated with anaerobic fungi or bacteria (P > 0. 05). Replacement of 50% alfalfa with purslane resulted in an 11% increase in digestion of neutral detergent fiber (NDF) in experimental diets incubated with anaerobic bacteria (P < 0. 05). Conclusion: Overall, the results of this experiment showed that the purslane plant is capable of manipulating ruminal fermentation activities in ruminant’ s nutrition and can be used as an effective factor in changing the environment and microbial population of the rumen.

Background and objectives: Increasing of livestock population has resulted in shortage of feed sources and competition between humans and animals. These problems have led to increasing concern in using by-products in animal feeding. But, most by-products have a low nutritional value due to the presence of high concentrations of lignocellulosic compounds and intermediate metabolites. In such a situation, a good solution is to use different processing methods to increase the nutritional value of these compounds or to use commercial enzyme mixture in animal fed. The aim of this study was to determine chemical composition of some agricultural by-product and also to the test the effect of a commercial enzyme mixture on their in vitro fermentation characteristic using gas production technique. Materials and methods: Soybean hull was provided from a soybean processing factory and pistachio hull and sugar beet pulp were provided from a local farm. In the laboratory soybean hull divided in to batch and one of them was under wind blowing separate soybean hull from cracked bean to produce bean-free soy hull. All samples were analyzed in duplicate for kjeldahl nitrogen, organic matter, neutral detergent fiber and acid detergent fiber. Gas production test was performed and metabolisable energy, digestible organic matter and volatile fatty acids were estimated. About 200 mg of each were incubated in 100 ml glass syringes and 30 ml of incubation liquid were added and were incubated in 39 ° C water bath. The amount of enzyme was 0. 05%. The gas production was measured in 2, 4, 8, 12, 24, 48, 72, 96, 120 hours. The results were analyzed in completely randomized design. Results: Greatest content of crude protein and lignin were measured in soybean hull (20. 49% of Dry Matter) and pistachio hull (8. 55 % of Dry matter), respectively. High amount of non fiber carbohydrate were noted in pistachio hull and sugar beet pulp. Enzyme had no effect on gas production in different hours, cumulative gas production, and the rate of gas production, organic matter digestibility, metabolisable energy and volatile fatty acids. Conclusion: Pistachio hull and sugar beet pulp had a large amount of non-fibrous carbohydrates and both soybean hull and sugar beet pulp had a small amount of lignin. Applying enzyme in the recommended dose did not have any effect on the fermentation parameters, digestible organic matter, metabolisable energy and short chain fatty acids. For future studies, using higher doses of the enzyme mixture and different times of enzyme application can be suggested.

Background and objectives: Planting of fodder plants with high production potential and high quality and adapted to Iran's climate conditions due to lack of forage in Iran has been considered. Today, in addition to common indigenous cultivars, sorghum hybrids cultivate growing in Iran is increasing. Not only does sorghum have a high yield, but it is well adapted to climatic conditions in most parts of Iran, especially in dry and temperate regions. This plant is able to absorb water better than other grasses. This plant is one of the most important forage forests in arid and semi-arid regions of the world. It can be productive due to adaptation to warm conditions and to a certain extent soil salinity and high water use efficiency. The purpose of this study was to determine the amount of yield, chemical composition, silage properties and energy metabolism, digestibility of organic matter, digestibility of organic matter in dry matter and volatile fatty acids by the method of gas production of forage sorghum cultivars. Materials and methods: In order to investigate the fermentation quality and nutritive value of five variety of sorghum silages, different sorghum cultivars Viz: ICRISAT623×R165, ICRISAT632×R165, ICRISAT625×165, ICRISAT520×166 and Speed feed were compared in completely randomized design with five replicates. For this purpose sorghum cultivars was obtained at dent stage, chopped with an average particle length of 2 cm and were preserved in 10 kg plastic boxes. Silos were kept at room temperature and opened at 45 days for determination of pH, DM, CP, EE, ADF, Ash, WSC and NH3-N. The Gas productions were used for determination of digestion and fermentation of samples. Results: Maximum dry matter by 1400. 5 Kg per hectare and metabolism energy by 131627 Mcal per hectare obtained in ICRISAT520×R166, whereas cultivars Speed Feed provided Minimum. The highest gas production, metabolisable energy, water-soluble carbohydrate (WSC), Volatile fatty acids and Ether Extract was observed in ICRISAT625×165, whereas, ICRISAT520×R166 and ICRISAT632×R165 had the lowest. Results indicated that there were significant differences between different cultures in percentage of DM, OM, CP, EE, Ash, ADF, WSC and NH3-N. The ICRISAT165×165 has the highest amount of cumulative gas, metabolizable energy, soluble sugar, volatile fatty acids and crude fat. However, ICRISAT520×R166 and ICRISAT632×R165 had lower values. There was no significant difference between cultivars in estimating of organic matter digestibility (OMD) and digestible organic matter in dry matter (DOMDM) using the amount of gas production. Conclusion: Based on the results of this study, ICRISAT520×R166 for dry matter production (18487 kg ha-1) and protein production (1400 kg ha-1) is recommended for cultivation in Golestan province. But in terms of yield per hectare, ICRISAT625×165 varieties is recommended for the rest of the cultivars.

Background and objectives: Numerous studies have reported heterogeneous genetic, residual, and phenotypic variances for production traits based on geographical region and herd production level. Ignoring the heterogeneity of variances will lead to improper ranking and selection of top sires and dams, loss of expected genetic gain and decreased efficiency of breeding programs. The objective of this study was to investigate the heterogeneity of variance components for milk test-day records as well as the impact of data pre-adjustment method on reducing the heterogeneity of variance, breeding values and changing the rank of top animals in population of Holstein cows in Iran. Materials and methods: The data set consisted of 1, 843, 985 milk test day records from 199, 353 first lactation cows in 983 herds calved between 1986 and 2016. Data had been collected by the National Breeding Center and improvement of animal production of Iran. Records were classified into three different groups based on the average of herd-year production level. The heterogeneity of variances was studied using the Leven’ s test. In order to reduce or remove the heterogeneity of variances, a pre-correction method was used. Variance components, heritabilities and breeding values were estimated using the ASREML program and animal model. Results: The results of Leven’ s test before data pre-correction were significant (P < 0. 01) which indicated the heterogeneity of variance. Data correction did not result in homogenous variances; but variance heterogeneity decreased up to 25%. Applying the pre-correction method resulted in slightly higher heritabilities so that heritability estimates were 0. 319 0. 007 and 0. 351 0. 009 before and after adjustment for heterogeneity of variance, respectively. Adjustment of data had a considerable effect on top animals, such that 14% and 20% of top sires and dams, respectively, were excluded from the top 1% listed animals when compared to the homogenous variance scenario. A substantial difference was observed in changing the rank of the top animals and ranking previously top-ranked sire and dam as 8 and 23 ranks after adjustment of heterogeneity of variance, respectively. Conclusion: Variance components of milk test-day records in Holstein cows were heterogeneous. Therefore, it could be suggested that the effects of heterogeneity of variance to be considered during evaluating and selecting genetically superior sires and dams.

Background and objectives: Acidosis is a nutritional disorder that is often caused by intake of the high amount of fermentable carbohydrate and an inadequate amount of fiber to induce buffering in the rumen. Hence, a strategy such as the use of microbial additives to prevent acidosis has been suggested. So, this study performed to investigate the effect of using three microbial feed additives (lactate producing and utilizing bacteria and Saccharomyces cerevisiae) in high-concentrate diet on in vitro anaerobic fermentation and digestibility in sheep. Our hypothesis was that the combination of microbial additives compared with individual use and without additives will have a positive effect on in vitro gas production parameters and digestibility in sheep. Materials and methods: For investigating the effect of microbial additives on the in vitro gas production (GP) parameter, ruminal fermentation and digestibility, eight treatments were studied based on as factorial experiment based on a completely randomized design; (1) control (basal diet (70% concentrate and 30% forage) without additive; (CON); (2) basal diet + Megasphaera elsdenii (Me); (3) basal diet + Saccharomyces cerevisiae (SC); (4) basal diet + Lactobacillus fermentum and Lactobacillus plantarum (FP); (5) basal diet + Me + SC (MSC); (6) basal diet + Me + FP (MFP); (7) basal diet + SC + FP (SCFP) and (8) basal diet + Me + SC + FP (MSCFP). Gas production techniques and two step digestion were used to evaluate the effectiveness of experimental treatments. Ruminal fluid was collected from three adult male Arabi sheeps that fed a diet based on forage. Results: Results showed that use of microbial feed additive improved GP and the highest amount of GP was observed in treatment MSCFP (P < 0. 05). However, the lowest amount of methane production was observed in MSC (P < 0. 05). Application microbial feed additives lead to improve in vitro fermentation parameter (OMD and ME) (P < 0. 05). Also, the highest amount of MCP was observed in MSC (P < 0. 05). Digestibility of CP and ADF significantly increased by FP and MSCFP (P < 0. 05). Although, digestibility of NDF numerically increased for SCFP. The concentration of total VFA and acetate significantly increased by MSCFP and CON. But, the highest concentration of propionate and butyrate were observed in MSC and FP. The use of microbial food additives decreased the ratio of acetate to propionate and also the ratio of acetate + butyrate to propionate (P < 0. 05). The highest concentration of ammonia N was observed in MSCFP and SCFP treatments (P < 0. 05). Conclusion: Given the positive results of the experimental treatments on gas production, reduced methane production and nutrient digestibility, the use of these microbial additives may be recommended for testing in high concentrated rations in sheep. Therefore, these FF, SCFP and MSCFP treatments are good candidates for using.