مجله پژوهش در نشخوار کنندگان
سال دهم شماره 4 (زمستان 1401)

Lack of green fodder and high cost of concentrated feed are among the limiting factors in the feed and livestock production industry. Therefore, ruminants use crop residues for feeding. These agricultural residues contain high cell wall content and low amounts of protein and metabolizable energy. To improve the quality of these by-products, various processes are used, including biological processes. Processing of straws using fungi has been shown to improve the nutritional value and degradability of their cell wall compounds. Therefore, this study was conducted to investigate the effect of Aspergillus oriza on chemical composition, volume of gas produced, degradability and the amount of volatile fatty acids produced by wheat straw.

In this study, two methods of liquid culture and solid culture of fungus were used to process wheat straw. The fungal contents were transferred to jars containing sterilized wheat straw and stored at 26 ° C for 25 days. The contents of the jars were dried and ground after 25 days and used for further experiments such as chemical composition, gas volume, dry matter degradability, Neutral Detergent Fiber and the amount of volatile fatty acids produced.

Processing with Aspergillus oryzae reduced dry matter, organic matter, Neutral Detergent Fiber and Indigestible neutral detergent fibers and was able to significantly increase the amount of protein so that solid culture increased protein by 2.94%. It was 5.86 percent. Processing of wheat straw by solid and liquid culture methods increased the volume of gas produced during 144 hours of incubation from 267.92 to 327.50 and 338.98 ml per gram of dry matter, respectively. Processing was able to increase the amount of Metabolisable energy and the amount of dry matter digestibility of straw and the highest amount of Metabolisable energy was observed in wheat straw processed by solid culture. The effective degradability of dry matter increased at the level of 2% passing through the rumen in wheat straw processed by solid culture method. Nutritional value index increased in both treatments compared to the control group. The degradability of Neutral Detergent Fiber was not affected by processing in solid culture but liquid culture reduced the degradability. Processing by both methods increased the total amount of volatile fatty acids produced and ammonia nitrogen of wheat straw.

Processing wheat straw by liquid and solid culture of Aspergillus oryzae improved some of the nutritional components of this crop and affected the amount of Neutral Detergent Fiber as well as insoluble Neutral Detergent Fiber. It has the ability to digest some lignin-cellulosic compounds in the cell wall, and since solid culture had significant beneficial effects compared to liquid culture, In general, it can be said that extracting the enzymatic complex of Aspergillus oryzae cultivar grown in solid culture medium and injecting it into wheat straw improves the nutritional value of straw.

Due to relative cost and dependence of the country on soybean meal imports, more attentions are given to new protein sources such as canola meal as a suitable alternative for soybean meal. Also, high protein degradability of meals in the rumen lead to loss of nitrogen (urea) through urine. Thus, meal processing methods are considered in order to reduce the rate of ruminal protein degradation and increase by-pass protein proportion which can improve animal productive performance and efficiency of nitrogen utilization. Therefore, the effects of substituting formaldehyde-treated canola meal (0.8 and 1.2% of meal crude protein) for untreated meal on feed intake, nutrient digestibility, productive performance and some ruminal parameters in lactating goat’s diet, and the possibility to compensate dietary protein deficiency using processed meal with 1.2% formaldehyde was investigated in this study.

Eight multiparous lactating goats with initial milk yield of 650-700 g/d were used in this study. Canola meal was treated with formaldehyde at two levels of 0.8 and 1.2% CP of meal and then used in the concentrate mixture. Four dietary treatments were: (1) control diet with 14.5 % CP containing untreated canola meal, (2) diet with 14.5 % CP containing formaldehyde-treated canola meal (0.8% CP), (3) diet with 14.5 % CP containing formaldehyde-treated canola meal (1.2% CP), and (4) diet with 12.5 % CP containing formaldehyde-treated canola meal (1.2% CP). In the last 7 days of each experimental period, feed intake and milk yield were measured daily and a subsample of produced milk was collected for milk component analysis. On the last day of each collection period, ruminal fluid samples were taken from goats to measure pH, NH3-N concentration and protozoa population count. Gross profit of milk production and economic estimation of experimental diets were also performed.

The DM intake of the goats was significantly increased by substitution of formaldehyde-treated canola meal in the diet (P<0.05), also reducing dietary CP level had the same effect. Feeding 1.2 % formaldehyde-treated canola meal only, or with reduced CP level of diet significantly increased production of milk, FCM, and fat, protein, lactose (P<0.05) while experimental diets had no effect on milk composition of the goats. Treating canola meal with formaldehyde did not affect ruminal pH, total protozoa, and Entodiniomorph, Holotrich and Cellulolytic count, while NH3-N showed a significant decrease by feeding 1.2% formaldehyde-treated canola meal at 3h post-feeding (P<0.05). Mean daily feed cost increased by feeding formaldehyde-treated canola meal and daily gross profit were higher with groups fed diets containing 1.2% formaldehyde-treated canola meal.

Due to present results, formaldehyde treatment of canola meal (1.2 %) enhanced feed intake and productive performance of lactating goats, moreover, treatment at this level had properly compensated the probable adverse effects of the lack of dietary crude protein on animal performance, overally. Therefore, formaldehyde treatment of canola meal (1.2 %) is recommended as a suitable choice to increase dietary bypass protein and positively impact productive performance, also to reduce the loss of nitrogen from body.

Identification of single nucleotide markers and different methods of genomic evaluation in the form of marker assisted selection at the genome level has led to considerable genetic progress in the economic traits of domestic animals. The success of genomic prediction is measured by its accuracy. Deterministic formulas determine the relationship between prediction accuracy and factors affecting prediction accuracy and therefore before running into genomic selection, it is possible to design an optimal program such as the appropriate size of the reference population to achieve the optimum level of selection accuracy. The aim of the present study was to evaluate the prediction of the accuracy of deterministic formulas and compare it with the accuracy of prediction of genomic breeding values in the simulated study.

Four deterministic formulas including Daetwyler et al formula, Goddard formula, Goddard et al formula and Rabier et al formula were used to predict the accuracy of genomic evaluation in different genetic architectures including different levels for heritability, reference population size and number of independent chromosome segments. The ShinyGPAS program was used to compare and plot the accuracy of prediction. In order to compare the performance of deterministic formulas with the accuracy of predictions in the simulated population, population simulations were performed using QMSIM software. For this purpose, in genome simulation, three levels of heritability of 0.1, 0.3 and 0.5 and two levels of reference population size of 1000 and 2000 individuals were considered and estimation of genomic breeding values was performed using Bayesian method A and Bayesian B using BGLR package in R medium

In low heritability, the highest prediction accuracy was observed in Goddard formula, which had the closest prediction accuracy (0.56) to the accuracy of genomic evaluation of simulated data estimated by Bayes A method (0.56). With moderate heritability (0.3), Goddard (0.74) and Rabier et al. (0.73) had the closest and most similarity to the accuracy of the simulated data. With population size increased from 1000 to 2000 individuals along with increasing heritability, the performance of deterministic formulas was closer to the accuracy estimated from simulation data by Bayesian methods and the most agreement was obtained in Goddard and Rabier methods. In the lower independent chromosome segments, the highest accuracy obtained by Rabier et al (0.860). With increasing chromosomal independent segments, the highest value of accuracy obtained by Goddard predictive formula.

The results showed that deterministic formulas have a good ability to predict the accuracy of genomic evaluation and their performance is linked to the genetic architecture. The results suggest that the predictions of accuracy, in general, using Goddard and Rabier formulas are more consistent with genomic estimation accuracy in the simulated data.

In order to increase efficiency and productivity, the need to use high-energy concentrate in dairy cows rations seems to be essential. This type of feed increases the risk of subacute ruminal acidosis, which leads to reduced dry matter intake, milk production and fat content. Therefore, different types of buffers are used to reduce the above consequences. Most buffers used in livestock farms include sodium carbonate, potassium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium oxide, magnesium carbonate and bentonite. Scientific reports on ration containing buffers has a significant effect of fermentation parameters such as volume of gas production, potential and consistent rate of gas production.

In this study, three types of rations for dairy cows compose 50:50, 40:60 and 30:70 forage to concentrate rations and 4 types of buffers and alkalizer including sodium bicarbonate, sodium carbonate, potassium carbonate and magnesium carbonate were examined by in vitro technique. The squence of this experiment included determining the initial pH, buffering capacity and buffering value index, determining the effect of buffers on the rate of fermentation parameters, microbial production and utilizable crude protein at the duodenum of different diets in terms of forage to concentrate ratios.

The results of this experiment showed that the highest acidogenicity value was related to the treatment of low forage rations containing sodium bicarbonate buffer, which was significantly different from the control treatment. The rate of microbial protein production, in gas technique,indicated that highest amount of microbial protein was produced in the low-forage ration containing sodium bicarbonate buffer. In the microbial protein production experiment, it could be used in the small intestine. The highest amount of protein that could be used in the small intestine at eight and Twenty-four hours was related to the treatment of low forage feed containing sodium bicarbonate buffer.

The results of treatments indicated that the buffering capacity of sodium carbonate, potassium carbonate and magnesium carbonate was significantly higher than sodium bicarbonate. The use of sodium bicarbonate and potassium carbonate buffers in low forage diets increases gas production and increases microbial protein. The amount of utilizable crude protein at the duodenum was the highest when using sodium bicarbonate and potassium carbonate buffers. It seem by usingthe componds with higher buffering capacity, the fate of ruminal nitrogen alter via increasing of microbial protein production and utilizable crude protein at the duodenum. It is better to use the mixture of these buffers based on the buffering capacity on in vivo.

In mammals, the need for minerals increases during the pregnancy period for the growth and development of the fetus and reaches to its maximum level at the end of the pregnancy period. Therefore, it is vital to supplement pregnant ewes with sufficient quantity of micro-minerals to preserve the fetus and improve the growth of the newborn lambs. Selenium and cobalt are two essential elements for ruminants, which play a major role in animal performance. Selenium is necessary to maintain the normal physiological functions of the body, it also plays an important role in the production of thyroid hormones and the conversion of thyroxine to triiodothyronine. Cobalt is one of the essential elements that presents in the structure of vitamin B12. Therefore, the present study aimed to investigate the effects of using slow-release bolus of selenium and cobalt on milk production and composition, reproductive performance and some blood parameters of Lori Bakhtiari's ewes.

One hundred Lori-Bakhtiari ewes with an average age of three to four years and an average weight of 47.55 ± 5.44 kg were used in a completely randomized design. Experimental treatments included: 1) control ewes without receiving slow-release bolus, 2) ewes receiving slow-release selenium bolus with a release rate of 0.3 mg per day, 3) ewes receiving slow-release cobalt bolus with a release rate of 0.3 mg per day and 4) the ewes receiving slow release bolus containing selenium and cobalt with a release rate of 0.3 mg of selenium and cobalt per day. Blood samples were collected at 76 days post-breeding (mid-gestation) and 30 days postpartum from all ewes, and analyzed for serum concentrations of selenium, zinc, iron, triiodothyronine, thyroxine and creatine-phospho-kinase activity. The number and percentage of pregnant ewes, number and percentage of healthy lambs born, number and percentage of twining, number and percentage of lambs with white muscle disease and number and percentage of lambs survived after 70 d were also recorded.

Supplementing ewes with slow-release boluses of selenium and cobalt had no effect on the number of pregnant ewes, lambs born healthy, twins, lambs with clinical symptoms of white muscle and the number of live lambs up to the age of 70 days (P<0.05). Milk production was higher in ewes receiving slow-release cobalt and selenium-cobalt tablets compared to other treatments (P<0.05). Milk fat percentage in the ewes receiving slow-release cobalt and selenium-cobalt bolus was significantly lower than other treatments (P<0.05). The percentage of milk protein in the treatment receiving slow-release selenium-cobalt bolus was significantly higher than the control treatment (P<0.05), but there was no significant difference with the other treatments (P<0.05). Serum concentration of selenium in ewes receiving slow-release selenium and selenium-cobalt boluses was significantly higher than other treatments (P<0.05). Serum concentrations of zinc, iron and serum creatine phosphokinase activity were not affected by the experimental treatments (P<0.05). Serum concentration of vitamin B12 in ewes receiving slow-release cobalt and selenium-cobalt boluses was significantly higher than the other treatments (P<0.05). Serum concentrations of triiodothyronine and thyroxine were not affected by the experimental treatments, but the ratio of thyroxine to triiodothyronine was significantly lower in ewes receiving selenium and selenium-cobalt than the other ewes (P<0.05).

The results showed that supplementing ewes with slow-release boluses containing selenium and cobalt at the time of estrus synchronization increased serum concentrations of selenium and vitamin B12 before and after parturition, and increased milk production and milk protein content.

Although nutrient imbalance does not play a role in the etiology of hypocalcemia and the existence of defects in physiological adaptations is the main cause of occurrences, the most common processes used to prevent the occurrences of hypocalcemia are nutritional and involve the use of some factors. Management in animal diets is close to calving. The aim if this study was to consider the effects of Anionic diets withdraw on metabolic response and productive and reproductive performance of Holstein cows during transition period.

Holstein cows (n = 200) with averaged parity 3.0±1.0 and BCS 3.5±0.5 randomly selected according to previous milk yield and assigned into one of two treatments: 1) control deit (DCAD= +100 mEq/kg dietary DM) and 2) Anionis diets (DCAD= -100 mEq/kg dietary DM). Diets fed from 3 week before expecting calving. At calving, 6, 12, 24, 36 and 48 h after calving and at 7, 14, 44 and 74 DIM serum concentrations of Ca, P and Mg were measured. Blood metabolites and liver enzymes were assessed on d 7 and 14 after calving. Dry matter intake (DMI) was monitored within the first 24 h of calving. Milk yield was recorded daily through 23 DMI thereafter it was recorded monthly until 2 months of lactation.

The yield of milk was greater in cows fed anionic diet compared to control group (40.39±0.73 vs. 39.27±0.55) within 3 weeks of lactation. Dry matter intake was lower in cows fed anionic diet compared to control group (12.10±0.12 vs. 12.90±0.13). Serum concentrations of P, Mg, beta-hydroxy butyric acid and non-esterified fatty acids were similar between groups. Mean concentrations of Ca in serum were not different between treatment groups at calving (0), 6 and 12 h after calving but were higher at 24 and 48 h after calving for cows that received anionic diets (P < 0.05). Incidence rates of dystocia, retained placenta and subclinical hypocalcaemia (P < 0.05) were less in cows received anionic diets. There were no differences between two groups in the incidence rate of clinical hypocalcaemia, endometritis and ovarian cysts (P > 0.05). Number of days to first service was shorter, the conception rate at first service was greater and open days was shorter in cows received anionic diets (P < 0.05). However, services per conception and Cows pregnant before 180 DIM were unchanged between two groups.

The results of the present study showed that the anionic diets increased milk production and first service conception rate via improve in health status of dairy cows.

Rams usually experience summer heat stress. In addition, rams due to high sexual activity during joining season experience doubled stress. Following the stress, the production of free radicals increases and oxidative stress related damages occur. High levels of free radicals cause sperm viability reduction, infertility and alter post-absorptive carbohydrate metabolism and glucose tolerance. There are various strategies to reduce the harmful effects of oxidative stress. The supplementation of antioxidants and some trace elements are important nutritional strategies have been recommended to combat harmful effects of oxidative stress. Therefore, the aim of this study was to investigate the synergistic effect of organic chromium or selenium on post-absorptive glucose metabolism and blood plasma antioxidant status in Mehraban rams.

Sixteen Mehraban rams (2-4 years old, with a body score of 2.5-3.5 and 70.14 kg in initial body weight) were randomly divided in to four groups (n=4). Treatments included two levels of Se 0 and 0.6 mg/ram/day (in form of yeast selenium) and, two levels of Cr, 0 and 1 mg/ram/day (in form of Cr-Methionine). The experiment lasted for 60 days. The supplements were fed daily and with the morning meal and total antioxidant capacity and malondyaldehyde levels were determined at days 30 and 60 of experiment. At the end of the experiment an intravenous glucose tolerance test was performed. To do this, 0.5 g of glucose/kg BW as sterile 50 % dextrose solution (w/v) was infused by jugular vein and subsequently blood glucose concentrations were determined at 5, 10, 15, 20, 25, 30, 45, 60, 90, 120, 150, and 180 min post-infusion. Then plasma glucose kinetics was calculated.

Time effect and treatment×time interaction did not impact malondialdehyde level and total antioxidant capacity. Interaction of chromium × selenium did impact total antioxidant capacity (P < 0.05) but, did not affect malondialdehyde level. Total antioxidant capacity was higher and malondialdehyde level was lower in chromium and selenium groups compared to control. Glucose basal and peak concentrations and amount of change (peak-basal concentrations) after glucose tolerance test did not differ among groups. Glucose concentrations were lower in chromium and selenium co-supplemented compared to chromium or selenium supplemented group at 15, 150 and 180 min glucose post-infusion and a significant chromium × selenium interaction was found (P < 0.05). Interaction of chromium × selenium did not impact glucose concentration at 20, 25 and 120 min post-infusion but glucose concentration at the mentioned time points in 1 mg level showed tendency to decrease compared to 0 levels. Plasma glucose clearance rate at 5 to 15 min post-infusion was higher and half-life was lower in chromium and selenium co-supplemented compared to selenium-supplemented group (P < 0.05). Main effect of chromium at the mentioned time interval was significant and 1 mg Cr/day had higher glucose clearance rate and lower half life (P < 0.05). Area under the curve at 5 to 15 min post-infusion did not differ between groups. Regardless of whether area under the curve was calculated from 0 to 30 min or 0 to 45 min, area under the curve was lower for chromium co-supplemented group compared to Se-supplemented group (P < 0.05).

Results of this study showed that organic chromium and selenium supplements alone or their combination improve the antioxidant status of rams in summer but, only the use of chromium alone or combined with selenium improves the post-absorption glucose metabolism characteristics. Also, the combined use of those two elements does not have a synergistic effect on post-absorptive glucose metabolism and blood plasma antioxidant status in Mehraban rams.

‎‏ ‏Biochar is one of the carbon compounds that has been introduced ‎as a suitable substitute for some food additives, including antibiotics. The purpose of this study ‎was to investigate the effect of using different levels of a type of mineral Biochar from ‎Kohbanan Biochar mine in Kerman on growth performance, digestibility of nutrients, some ‎blood parameters and rumen fermentation of weaned Holstein calves.‎

‎‏ ‏In the present study,‎‏ ‏‎40 Holstein weaned calves (male and female) with ‎an average age of 128±7 days and an average weight of 99.4 ± 0.4 kg were used in a completely ‎randomized design with 4 treatments and 10 replications. Experimental treatments include: 1) ‎basic diet without mineral Biochar (control diet), 2) basic diet with 0.33% mineral Biochar, 3) ‎basic diet with 0.66% mineral Biochar, 4) The basic ration was with 1% mineral Biochar (all ‎based on the percentage of dry matter of the ration). A two-week habituation period was ‎considered. Weaned calves were weighed upon entering the design and weighing was repeated ‎every two weeks until the end of the experiment. Calves were kept in individual stalls and fed ‎experimental diets for three months. During the experiment, the feed consumed three times a ‎day was provided to the calves at the limit of optional consumption. The amount of feed ‎consumption was measured daily and average daily weight gain, average feed consumption and ‎feed conversion efficiency were calculated. At the end of the experiment, a blood sample was ‎taken from the jugular vein of the calves and blood parameters including urea nitrogen, glucose, ‎total protein and triglyceride, albumin , alanine aminotransferase, aspartate transaminase, very ‎low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein were determined. ‎Also, at the end of the test, the digestibility of dry matter, organic matter, protein Crude, ‎insoluble fiber in neutral detergent, pH and ammonia nitrogen concentration of rumen liquid ‎were measured.‎

The results showed that the use of mineral Biochar in feeding weaned calves had no ‎significant effect on dry matter consumption, daily weight gain, total weight gain and average ‎feed conversion efficiency. The highest apparent digestibility of dry matter, organic matter, ‎protein and insoluble fiber in neutral detergent was related to calves fed with a diet containing ‎‎1% Biochar (P< 0.05). The concentration of glucose, urea and high-density lipoproteins in the ‎blood of calves fed with a ration containing one percentage of Biochar was higher than that of ‎the calves of the control group (P<0.05). The concentration of cholesterol, triglyceride, aspartate ‎transaminase, alanine aminotransferase, albumin, total protein, very low density lipoproteins, ‎low density lipoproteins, gamma globulin did not differ significantly between the experimental ‎groups. Also, calves fed with a diet containing 1% Biochar had more ammonia nitrogen and ‎lower rumen pH than the control group (P< 0.05).‎

In general, the results of this experiment showed that the use of 1% mineral ‎Biochar in the ration of weaned calves can have positive effects on digestibility, some blood ‎parameters and rumen fermentation.‎