مجله پژوهش در نشخوار کنندگان
سال هشتم شماره 3 (پاییز 1399)

Diarrhea is one of the most common diseases in young dairy calves. This disease results in economic loss on dairy farms. So, fighting this disease needs more researches. Addition of high fiber byproduct to calf starter diet may have beneficial effect on preventing calf diarrhea. Furthermore, plane of milk or milk replacer during weaning could impact calf health. We hypothesized that partially replacing corn grain with high-fiber byproducts (sugar beet pulp) would decrease the incidence and severity of common calf diseases, diarrhea and pneumonia. As two diseases often occur in dairy calves and decreases dry matter intake and average daily gain. In addition, their occurrences, usually needs medication, consequently increase farm costs. Hence, the purpose of this research was to examine the effect of substituting corn grain as a source of starch with sugar beet pulp as a high fiber feed in starter diet and high plane of milk replacer nutrition on health status Holstein calves during pre-weaning period.

Forty-eight neonate calves (3-d old; 40.1 ± 0.84 kg BW) were assigned to four experimental groups, in a randomized completely design with 2 × 2 factorial arrangements. Experimental factors include two starter diets containing steam-flaked corn grain and sugar beet pulp and two plane of milk replacer nutrition including low plane (4 L milk) and high plane (8 L milk). So, the experimental groups including 1- calves received corn grain diet and low plane of milk replacer nutrition, 2- calves received corn grain diet and high plane of milk replacer nutrition, 3- calves received sugar beet pulp diet and low plane of milk replacer nutrition and 4- calves received sugar beet pulp diet and high plane of milk replacer nutrition. Calves rectum temperature was recorded daily and fecal score and general health signs were determined.

The results showed that calves fed diet containing beet pulp in comparison to calves fed diet containing corn grain had lower chance to develop pneumonia, but higher to diarrhea. Increasing plane of milk replacer nutrition had no effect on developing diarrhea, but calves fed high plane of milk replacer nutrition in comparison to calves fed low plane of milk replacer nutrition had higher chance to develop pneumonia. General appearance (score ≥2) and frequency and duration of diarrhea and pneumonia were not different between experimental groups, but calves received sugar beet pulp diet and low plane of milk replacer nutrition in comparison to other experimental groups experienced fewer days to high rectal temperature.

It is concluded that calves fed diet containing beet pulp due to higher diarrhea occurrence and duration, greater medical cost for pneumonia and less general appearance, had lower performance in comparison to calves fed diet containing corn grain. Milk replacer plane of nutrition had no effect on diarrhea.

In recent years, many countries and regulatory agencies, including the European Union, have banned the use of antibiotics and growth stimulants in animal nutrition, so it is necessary to find suitable alternatives to these compounds in animal feed, especially animal animals. Synbiotic supplements (a mixture of probiotics and prebiotics) reduce the population of pathogenic microbes in the gastrointestinal tract and improve the performance of the host animal by increasing their interaction. Probiotic, prebiotic, and synbiotic supplement can be controversial options for replacement with antibiotics and growth stimulants. Considering the effective effects of these beneficial additives on the growth performance of fattening animals, this study was performed to investigate the effect of different levels of Biomin®IMBO synbiotic supplements in diet on growth performance, apparent digestibility nutrients and some blood parameters fattening Zell lambs.

To perform this study, 24 mixed fattening Zell lambs were examined with a means age of 5±0.55 months and a means initial weight of 26±2 kg in a completely randomized design for 90 days. Experimental treatments included control treatment (without the addition of synbiotic supplement) and treatments containing 2.0, 4.0, and 6.0 g of synbiotic supplement per lamb per day. The synbiotic supplements used was Biomin®IMBO, which included the bacterium Enterococcus fascium and fructooligosaccharide and seaweed extract. The daily diet was given as a TMR to the animal twice and the amount consumed was recorded. Live weight measurement was performed every 14 days with 12 hours of feed and water deprivation. Measurement of the apparent digestibility of nutrients in the last days of the experiment as well as the study of carcass traits and blood parameters were performed on day 90 of the experiment.

The results of growth performance showed that there was a statistically significant difference between experimental treatments in daily weight gain and feed conversion ratio (P <0.05). Daily weight gain and feed conversion ratio improved significantly in the treatment containing 6.0 g of synbiotic supplement. The results of apparent digestibility nutrients in experimental diets showed that there was a statistically significant difference between dry matter, NDF and ADF between experimental treatments (p < 0.05). Treatments containing 4.0 g of synbiotic supplement had the highest apparent digestibility of dry matter and treatment containing 6.0 g of synbiotic supplement had the highest apparent digestibility of NDF and ADF. The results of experimental carcass traits at the end of the experiment showed that there was no statistically significant difference between the experimental treatments. The results of some blood parameters at the end of the experiment showed that there was a statistically significant difference in blood glucose and BUN levels between experimental treatments (P <0.05). Treatments containing 4.0 g of synbiotic supplement had the highest blood glucose levels and control treatments had the highest levels of BUN.

The overall result of the study showed that adding Biomin®IMBO synbiotic supplement at the level of 6.0 g in the diet improved daily weight gain and feed conversion ratio. There was also an improvement in the apparent digestibility nutrients in dry matter, NDF and ADF by consuming levels of 4.0 and 6.0 g of Biomin®IMBO synbiotic supplement.

The use of agricultural by-products and waste because of its high value of nutrients, is possible in the preparation of animal feed. About 950 tons of Mentha pulegium pulp is produced annually in Iran. If this pulp dries well, it can be used in animal feed due to its nutritional value. Due to the fact that moisture is a limiting factor for animal feed storage, ensiling can eliminate this limitation. This study was to evaluate of chemical composition of Mentha pulegium pulp silage with wasted date and its feeding effects on - dry matter intake, microbial protein yield and blood parameters in sheep.

400 kg of Mentha pulegium pulp were mixed thoroughly with 30 kg of wasted date at levels of 0 (control), 5, 10 and 15 % (DM basis) and ensiled for 45 days. After determining the chemical composition and sensory assessment of the silages, level of 20 % (DM basis) was used in experimental diets. For determine the effects of Mentha pulegium pulp silage on sheep, four mature ram (with 40 ± 2 live weight) were used in a change-over design with four periods of 21 days. In the 5 days at the end of each period at 0, 3, 6 and 9 h after morning feeding, rumen fluid was sampled from sheep by esophagous tube and were filtered through three layers of cheesecloth. Blood samples were collected at the end of each period and 4 h after morning feeding in 10 mL. To determine the amount of allantoin and microbial protein synthesis, the daily urine produced during 24 hours was collected.

According to the sensory assessment, silages containing of wasted date get score of very good of 20. Adding wasted date to Mentha pulegium pulp increased the DM and ether extract of silages. DM intake and digestibility of DM, crude protein and NDF of experimental diets were not affected by silages of Mentha pulegium pulp with different levels of wasted date. Nitrogen intake, nitrogen excretion and the percentage of nitrogen retention were not affected by experimental diets. Total purine derivatives and microbial protein synthesis did not change. The level of blood cholesterol and albumin were significantly changed by feeding diets containing Mentha pulegiumsilage with wasted date (p < 0.05).

In conclusion, could be used Mentha pulegium pulp silage up to 20 % without additives or with wasted date in sheep diet.

Some previous researches have shown that dietary supplementation with some vitamins and trace elements can increase the ability of animals semen preservation during liquid storage or freezing. Therefore, the aim of this study was to investigate the effect of dietary supplementation of organic selenium and chromium on ram semen quality during liquid storage at 4 °C.

Numbers of 16 Mehraban rams, with ages ranging from 2-4 years and 69.75±10.44 kg average body weight, were divided into four groups of four and were fed by a basal diet consist of 70% forage and 30% concentrate. The experimental design was 2×2×4 factorial experiment based on randomized complete block design. The experiment lasted for 60 days. In this experiment, three factors were including selenium at two levels (0 and 600 µg/day/ram selenium as yeast-selenium), chromium at 2 levels (0 and 1000 µg/day/ram chromium as chromium-methionin) and time at 4 levels (0, 24, 48 and 72 hours after storage). Chromium was fed to rams using edible capsule shells and also selenium by drencher after dissolving in distilled water. In the last three weeks of the experiment, semen samples were collected 3 times. Semen samples after collection was diluted with tirs-egg yolk base extender and stored at 4°C for 72 h. Sperm cells viability, membrane integrity, abnormal morphology, total motility and progressive motility and some motion parameters is detected by computer-assisted sperm analysis at 0, 24, 48 and 72 hours after storage.

The effects of chromium, time and their interaction and also selenium × chromium interaction, selenium × chromium × time interaction were significant for sperm viability and membrane integrity (p < 0.05). The effect of selenium and selenium × chromium interaction was not significant for viability (p>0.05) but, the effect of chromium, selenium and time and also their interaction for membrane integrity was significant (p < 0.05). The viability reduced over time significantly (p < 0.05) and sperm viability in rams receiving the diet contained 1000 μg chromium, was higher than diet without chromium after storage at 4°C for 48 and 72 hours (p < 0.05). In addition, sperm viability in rams receiving the diet contained 600 μg selenium was higher than diet without selenium after storage at 4°C for 48 hours (p < 0.05). Adding 1000 μg chromium to diet containing 600 μg selenium, increased significantly sperm viability after storage at 4°C for 48 and 72 hours (p < 0.05). The membrane integrity reduced over time significantly (p < 0.05) and sperm membrane integrity in rams receiving the diet contained 1000 μg chromium was higher than other groups after storage at 4°C for 24 and 48 hours (p < 0.05). The effect of selenium and chromium and also their interaction was not significant for computer detected parameters (p < 0.05). Interaction of selenium and chromium for abnormal morphology was significant (p < 0.05) but the effects of chromium, selenium, time and their interaction was not significant (p>0.05). Total motility, velocity in curvilinear line, velocity in straight line, velocity in average path decreased over time during semen storage at 4°C (p < 0.05) and diet supplementation of selenium and chromium did not change these parameters (p>0.05). Progressive motility, abnormal morphology and straightness did not affected by time, selenium and chromum.

Generally, dietary supplementation of organic selenium and chromium in rams leads to increased sperm viability and membrane integrity during chilled liquid storage. Dietary supplementation of selenium and chromium did not change computer detected parameters during semen storage at 4°C. In general, the use of organic selenium and chromium in the diet of rams may increase the ability of sperm storage for artificial insemination.

Treatment of bacterial diseases with antibiotics has problems such as antibiotic resistance and side effects. Essential oils of medicinal plants have antibacterial effect and are suitable alternatives. Lavandula stoechas and Origanum majorana are two members of lamiaceae family that have shown antibacterial effect against some bacteria. Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae bacteria are major bovine mastitis-causing bacteria. Therefore, this study examined the antimicrobial activity of Lavandula stoechas (lavender) and Origanum majorana (marjoram) essential oil against these bacteria in comparison with gentamycin and amoxicillin/clavulanate antibiotics.

Chemical compositions of essential oils were determined by GC/MS. Broth dilution testing using macrodilution was performed to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of essential oils and licospectinomycin as positive control and the inhibition zones of oils, gentamycin and amoxicillin/clavulanate antibiotics were assayed by disk diffusion method. The effect of sub-MIC concentrations of essential oils on tested bacterial count was obtained at 0, 6, 10 and 24 hours and growth curve were plotted as log cfu/ml.

Main components of the Lavandula stoechas and Origanum majorana oils were 17-pentatriacontene (42.15%), linalyl acetate (26.82%), eucalyptol (18.87%), linalool (5.7%) and 3-cyclohexene-1-ol,4-methyl-1-(1-methylethyl)-,(R)-(44.84%), α-terpineol (6.83%), P-cymene (6.75%), respectively. MIC and MBC values ranged from 0.15 - 0.62% for lavender and 0.62 - 1.25% for marjoram. MIC and MBC of licospectinomycin antibiotic were 0.07 - 0.31% and 0.15 - 0.64%, respectively. The lavender and marjoram essential oils had the most effective against S. aureus and MIC and MBC values were 0.15% and 0.31%, respectively. Also, the most effective of Lincospectinomycin antibiotic was against S. aureus and MIC and MBC values were 0.07% and 0.15%, respectively. The Lavandula stoechas and Origanum majorana oils at sub-MIC concentrations significantly reduced the bacterial population at 24 h. The inhibition zone of lavender and marjoram essential oils had no significant difference against S. aureus with gentamycin and amoxicillin/clavulanate antibiotics and against E. coli with gentamycin but against S. agalactiae were significantly lower than gentamycin and amoxicillin/clavulanate.

Essential oils of Lavandula stoechas and Origanum majorana had antibacterial activity against Staphylococcus aureus, Streptococcus agalactiae and Escherichia coli bacteria in vitro. This effect had no significant difference against S. aureus with gentamycin and amoxicillin/clavulanate and against E. coli with gentamycin that show satisfactory effects of oils. Clinical studies on therapeutic effects of Lavandula stoechas and Origanum majorana oils on different diseases such as bovine mastitis are recommended.

One surefire way to increase income and profit is to pay attention to the viability of the dairy cow and increase the efficiency of each livestock unit. The purpose of this study was to determine the efficiency and effective factors on optimal herd life in dairy cows with dynamic data envelopment analysis and planning model in Ardabil city.

The data of this study were related to 1397 time series of dairy farms in Ardebil city which were analyzed by system analysis method, economic system of dairy herd and income and cost components, and each of these components was subdivided into other sections. Then, using mathematical models, we simulated a bioeconomic model and optimized it with the help of the Matlab software Compecon toolkit. The dairy cattle were described with state variables including lactation period, milk production capacity and different gestation states. In order to design data envelopment analysis model, several inputs and outputs in the production process were studied. The main variables used in the study included, herd size by apex, feed and concentrate in kg, manpower by day, health by Frequency of milk, milk production and livestock manure production per kg and total income were determined. And Deap 2.1 software based on minimizing the amount of input per unit of product was used for performance calculations.

Optimal herd life (from first calving to elimination) was 4.55 years under optimum conditions. The results also showed that the technical efficiency with constant return to scale is 0.719 and with variable return to scale equal to 0.899 and scale efficiency was calculated to be 0.888. The overall technical efficiency value was 0.99, allocative efficiency 0.583 and economic efficiency 0.579.

The effect of heifer price, milk price and discount rate on optimum lifespan showed that with increasing heifer price, milk price decrease and discount rate increase elimination percentage decreased and optimum lifespan increased. The results of data envelopment analysis showed that in terms of variability of efficiency relative to scale, increase in herd size and health costs and decrease in forage, concentrate and labor costs, respectively, 14.18, 0.83 , 2.8% and 5% result in inefficient herds being maintained by maintaining levels. Therefore, in order to make an inefficient unit effective, changes must be made to the inputs and outputs of that unit. By specifying the differences between the inefficient and inefficient units, appropriate strategies are designed to eliminate the gap between them.

The reproductive performance of dairy cow is directly linked to uterine involution and resumption of ovarian cyclicity in the postpartum period. Many factors, such as negative energy balance, metabolic diseases and hormonal agents can affect reproductive performance in the postpartum period. Hypocalcemia through reduced Feed intake, reduced nutrient supply to the ovary and delayed return to normal uterus function has a potential role to reduce the reproductive performance of cows after parturition. The aims of this study were to examine the association of peripartum concentrations of calcium with reproductive performance and establish cow level critical threshold for calcium to predict conception to first service.

the study was conducted on 97 Holstein dairy cows. Serum concentrations of calcium were measured in all cows on day 10 prepartum, parturition, 1-2 days after parturition and on the weeks 1, 2, 4 and 6 postpartum. Based on Pregnancy success after the first insemination, the interval from calving to first insemination, the interval from calving to first pregnancy and number of services per conception, cows were divided to two, two, three and two groups respectively and differences of calcium concentration were evaluated among these groups. ROC analysis was applied to determine the critical calcium threshold at different times for predict pregnancy success after the first insemination.

the results showed that calcium concentration in pregnant cows with the first insemination was significantly higher than non-pregnant cow in the fourth week. Also, the cows that were became pregnant before 80 days after parturition had the significantly higher calcium concentration at 1-2 days and the fourth week after parturition than other cows. Based on results of ROC analysis, the calcium concentration at the fourth week after parturition (P=0/04) was appropriate to predict the pregnancy success after the first insemination. The optimum critical threshold that had the highest combined sensitivity (57/1%) and specificity (62/3%), for calcium in the fourth week was 9.05mg/dl. In the cows with success pregnancy before 80 days after parturition the calcium concentration was significantly higher than other cows (P=0/03).

the results of this study showed that there was a significant relationship between change in calcium concentration and reproductive performance indexes in the postpartum period. It seems that the monitoring of blood calcium concentration in the fourth week after parturition is a complementary index along with other reproductive performance indexes to evaluate the possibility of successful pregnancy after parturition Key words: calcium, postpartum, dairy cow, reproductive efficiency

Heat stress is one of the environmental stressors that has significant effects on the dairy cattle industry. Environmentally induced hyperthermia or heat stress (HS) during dry period has subsequent negative effects on performance of dairy cows .In utero hyperthermia can have a lasting imprint on offspring growth, behavior, and metabolism and also impairs the future HS response in a mammalian modelThe biological mechanisms by which the thermal stress effects on the livestock production performance can be somewhat explained by reduced feed intake, but it is more relevant to hormonal changes, reduced rumination and absorption of nutrients, as well as increased maintenance requirements, which reduces the amount of nutrients / energy for production purpose. The objective of this study was to identify the direct and indirect effects of acute HS during the last gestation on nutrient digestibility and rumination behavior of dairy cows.

Holstein dairy cows (n= 10/treatment) with similar parity and body weight (BW), were randomly assigned to one of the three following treatments during 45 d before calving: 1) Cooling and ad libitum feed intake (TN), 2) Cooling and pair-feeding (CLPF), and 3) HS and ad libitum feed intake (HS). Cows in all groups received individually the same diet. During the experiment, daily temperature and the relative humidity were recorded. During the 26-21 d and 10 to 5 d before calving, the feed intake behavior was record for 24 hours. Cows were housed in individual free stall barn, bedded with straw, which for CLPF and CL cows consisting of shade, sprinklers, and fans that were turned on from 0700 to 1900 h, whereas HS cows were provided only with shade. During the experiment, all cows had free access to clean drinking water. Fans were installed in waiting areas, and sprinklers were applied behind the feed bunk. Diameter of fans was 76 cm, and jet 0.47 cm3 air per fan.Nutrients digestibility in feed and fecal samples was measured on 26 - 21 d and 10 - 5 before calving.

Heat stressed and feed restricted cows had lower feed intake. Heat stressed and food restricted cows had lower eating time significantly compare to the control group. Heat stressed cows had the lowest rumination activity. Also, the heat stressed cows had significantly lower resting time than the control group. Also, heat stress significantly reduced the dry matter and NDF digestibility.

Late gestation heat stress caused decreased feed intake. Also, nutrient digestibility of the diet negatively affected by heat stress. However, feed restriction in late gestation did not have significant effect on nutrient digestibility than the control group. In addition, heat stress reduced the rumination activity and resting time of the cows.