جستجوی مقالات مرتبط با کلیدواژه « arabi sheep » در نشریات گروه « علوم دام »

 Arabi sheep population includes almost 55% of the local sheep population in Khuzestan province. Lamb mortality is a universal problem in sheep breeding that may be reached to 20-40% of total lambs born and could impact the genetic improvement, animal welfare and economic viability of sheep breeding, adversely. Research on improving survival of lambs is likely to have a higher pay-off than research on improving the number of lambs conceived. Lamb survival is a compound trait affected by many various factors related to climate, management, lamb and ewe behavior and genetic effects. Lamb survivability is controlled by genetics of the animal, contributed by direct genetic and maternal effects and also by environmental effects. There are disagreements among researchers about using a suitable model to analyze the survival traits, and each researcher has suggested the use of specific models. In general, the use of linear and threshold models has been suggested for survival trait analysis. Although survival has great economic importance, in the studies conducted on Iranian livestock, less attention has been paid to it. The aim of this study was to analyze the genetic parameters for the survival of Arabi lambs from birth to one year of age using linear and Weibull models.

 in this study, 5452 lamb survival records collected by the Jahad Agricultural Organization of Ahvaz from 1993 to 2005 were used. Traits included were cumulative survival from birth to the end of one year and on a monthly basis. In order to estimate genetic parameters using linear models, the Restricted Maximum Likelihood (REML) method was used in Wombat software based on a univariate analysis. The Weibull model and Matvec software were also used for estimating variance component and genetic parameters of Survival rate.

 Different models compared using the likelihood ratio test. For survival traits until 1, 4, 5, and 10 months, the model 4 was suitable, which include the direct additive genetic effect, maternal additive genetic effect and their covariance. In the case of until 2 months, the best model was the model 3, which include the direct and maternal additive genetic effects. For until 3, 8, 9, and 12 months, model 1 including direct additive genetic effect was selected. And for other traits Model 5 (direct additive genetic, maternal additive genetic, and maternal permanent environmental effects) was chosen as the best model. The direct heritability of survival rate estimated from different linear models was in the range of 0.025 to 0.061. In general, despite the high economic importance of survival in the breeds until one year of age, due to low estimates of the inheritance of these traits using linear models, it cannot be expected that genetic selection alone can make significant genetic progress. The genetic variance component among sires, heritability on the logarithmic scale, heritability on the original scale, and effective heritability obtained from Weibull sire model were increased to a peak point at 4 months. After that, a decline occurred until 5 months, and then a fluctuation was observed until 9 months. A limited increase was found in the 11 and 12 months. The heritability of sire model, in the logarithmic scale, had a low to medium range (0.13-0.25), and in the original scale had a medium to high range (0.39-0.75). The effective heritability was estimated in the medium range. Estimated values of the survival heritability using the Weibull model was greater than the value obtained from the linear animal model. Although heritability estimations for survival and mortality is low, it is possible that genetic progress may be enhanced by selecting lambs with higher breeding value for survival.

 Estimation of the genetic parameters for survival lambs from birth to one year of age using linear and Weibull models were low vs medium to high, respectively. Therefore, based on the results of linear models, response to  direct selection to improve the survival of lambs in this breed will be very slow, and more attention should be paid to improving non-genetic factors and indirect selection and outbreeding, but based on The results of Weibull models, it seems that the rate of response to genetic selection to improve survival trait is faster using these models compared to the linear models, suggest that lamb survival could be improved  through direct selection and could be included in the Arabi sheep selection  index.

In this study environmental effects, genetic and phenotypic trends for body weight traits in different age in Arabi Sheep estimated. In this study used a total of 11365 records on birth weight, 6930 records of weaning weight, 3275 records of 6 month weight, 2043 records of 9 month weight and 1750 records of 12 month weight. The data used in this study, collected during 1994-2015 in Khuzestan province. The breeding value of the animal were estimated by restricted maximum likelihood method. The SAS statistical software was used to evaluate the effect of environmental factors and Wombat software was employed to estimate animals breeding value. The SPSS software was used for estimation of the trends. Environmental factors such as birth year, Sex, birth type and age of Mather were significant on all traits and were fixed effects in model. Animal’s age was introduced to the model as covariate. Estimation of direct genetic trend for birth weight, weaning weight, 6 month weight, 9 month weight and 12 month weight were as -0.07, -17, 2, 1 and 1 gr per year respectively. The phenotypic trend for considered traits was respectively 5, 256, 76, 83 and 194 gr per year. It can be concluded that reduction of the average breeding value in the genetic trends and the oscillation in the phenotypic trend are due to reduction of recording accuracy and entering livestock with low breeding value to the herd or negative impact of environmental factors on the production potential of livestock.

Myrtle is from Myrtaceae family with scientific name, Myrtus communis. Myrtle leaves mainly containing terpynolen, cineol, linalool, terpineol and acetate lynalyl. Also including the active ingredients as phenolic acids such as galic acid, vanillic acid and ferulic acid, tannins such as galotannin and flavonoids such as, myrcetin, catechin and quercetin. Many plants synthesis secondary metabolites that have antimicrobial activity, regulation of ruminal fermentation and subsequently improve nutrient intake. Information on the use of myrtle leaves in ruminant nutrition is rare, so this experiment was designed to investigate the effect of myrtle leaves on digestion, some blood and rumen parameters and protozoa species in Arabi sheep.   At first step, the appropriate level of myrtle leaves between the levels 0.2, 0.4 and 0.6 % with diet 70:30 concentrate to forage was determined by in vitro methods (gas test and tilly and terry method). Rumen fluid was collected from sheep before the morning feeding. About 200 mg sample (1.0 mm screen) incubated in 100 ml vials with 35 mL buffered rumen fluid under continuous CO2 reflux for 2, 4, 6, 8, 10, 12, 16, 24, 48, 72 and 96 h, at 39°C. Cumulative gas production data were fitted to the exponential equation Y=B (1−e−ct). Partitioning factor, microbial biomass and truly digested organic matter was calculated. For determination of partitioning factor at the end of each incubation period, the content of vials was transferred into an Erlenmeyer flask, mixed with 20 mL neutral detergent fiber solution, boiled for 1 hour, filtered, dried (in oven at 60 °C for 48 h) and ash. Digestibility of dry matter and NDF of samples were determined using tilly and terry method. Rumen fluid was collected from animals, and were mixed with McDougall buffer in a ratio 1:4. After gasifying with CO2, tubes were incubated at 39 ˚C. After 48 h of fermentation, 6 mL of 20% HCl solution and 5 mL pepsin solution were added and the incubated for 48 h, simulating post-ruminal degradation. After incubation, the residual substrates of each tube were filtered and used to determine digestibility of DM and NDF.
At the second step of experiment, the appropriate amount of myrtle leaves; 0.4 %; was used in feeding 8 Arabi sheep (23±1.5 kg) for 30 days. In the end of experiment, feed intake, digestibility, protozoa morphology, some blood metabolites and rumen parameters were measured. Data were subjected to analysis as a completely randomized design using the General Linear Model (GLM) procedure of SAS. version 9.1. The Duncan multiple range test was used to compare means at P< 0.05.   The results of in vitro step showed that the best fermentation, gas production and digestibility were for 0.4% the myrtle leaves. On the base of the result of in vivo step, using of myrtle leaves had not any effect on dry matter and organic matter intake (P>0.05). Treatment containing myrtle leaves had the highest protein intake in compared with control treatment (P<0.05). Digestibility of crude protein and NDF in diet with myrtle in comparison to control significantly increased (P<0.05). But there was no significant difference between the dry matter, organic matter and ADF digestibility of sheep’s (P>0.05). Protozoa population was significantly not affected by inclusion myrtle leaves in the diet (P>0.05). Ammonia levels in diets treated with myrtle (8.29) significantly reduced in compared with the control (16.5) (p<0.05). The myrtle leaves treatment decreased triglyceride and blood glucose of sheeps (P<0.05). Factors such as period of adaptation to medicinal herbs and interaction with other dietary components and their amounts in the diet, can influence the amount of dry matter intake. Essential oils according to chemical structure, resources and activities have different effects on rumen fermentation and animal performance. The negative effect of active ingredients of medicinal plants on ammonia-producing bacteria caused to decrease of rumen ammonia production, also reducing protozoa and swallowing of bacteria that can be other reason for ammonia decrease. Polysaccharides, flavonoids, glycoproteins, polypeptides, steroids, alkaloids and pectin in plants such as myrtle can justify the hypoglycemic properties of these plants. Medicinal plants and their extracts are effective in reducing blood cholesterol and other lipids. It is reported essential oil reduces pH of intestinal tract through production of degrading enzymes of bile, also inhibit the activity of HMG-COA enzyme.   According to the results, it seems 0.4 % myrtle leaves has beneficial effects on digestibility and can reduce blood glucose and triglyceride; therefore, maybe it can be used as an herbal supplement in Arabi sheep diet.

Medicinal herbs such myrtle leave are used in animals, and secondary metabolites of them alter rumen fermentation in livestock. Essential oils of myrtle leaf are containing terpinolene, cineole, linalool, terpineol and linalyl acetate. Also there are phenolic acids such as gallic acid, vanillic acid and ferulic acid; tannins such as galotannin and flavonoids such as myrcetin, catechin and quercetin in myrtle oil. Myrtle leave was used traditionally in the treatment of bronchitis, sinusitis, diarrhea and hemorrhoids. The studies showed that myrtle essential oils are used greatly as a food preservative. Also researchers reported that secondary metabolites of medicinal plants have hypoglycemic properties and reduce cholesterol and other blood lipids. There is rare information about using of myrtle leaf in livestock nutrition. Therefore, purpose of this experiment was to evaluate the effect feeding of myrtle leave on the gas production characteristics and fiber digestion and protein in Arabi sheep and effect of myrtle essential oils on gas production parameters. Material and In this trial, 8 Arabi sheep (about 9 months’ age and average weight 23±1.5 kg) were used and fed with diet without myrtle leave and diet containing 0.4 percent myrtle leave in diet 70:30 concentrate to forage for 30 days (4 replicates per treatment). In the end of experiment, fermentation parameters, gas production and in vitro digestibility of wheat straw and soybean meal with rumen fluid of sheep’s fed with experimental diets were measured. Rumen fluid was collected from animals before the morning feeding. About 200 mg sample (1.0 mm screen) incubated in 100 ml vials with 35 mL buffered rumen fluid under continuous CO2 reflux for 2, 4, 6, 8, 10, 12, 16, 24, 48, 72 and 96 h, in a water bath maintained at 39°C. Cumulative gas production data were fitted to the exponential equation Y=B (1−e−ct), where B is the gas production (mL) from the fermentable fraction, C is the rate constant of gas production (mL/h), t is the incubation time (h) and Y is the volume of gas produced at time t. Partitioning factor (PF), microbial biomass and truly digested organic matter was calculated by Makkar and Becker. For determination of partitioning factor at the end of each incubation period, the content of vials was transferred into an Erlenmeyer flask, mixed with 20 mL neutral detergent fiber solution, boiled for 1 hour, filtered, dried (in oven at 60 °C for 48 h) and ashed. In the second trial, the effect of different levels of myrtle essential oils (0, 0.05, 0.1 and 0.15 mL) in diet 30% forage and 70% concentrate on gas production parameters was measured by gas production method. Essential oils of myrtle leaf were taken by clevenger. Digestibility of dry matter and NDF of samples (wheat straw and soybean meal) were determined using tilly and terry method. Rumen fluid was collected from animals, and were mixed with McDougall buffer in a ratio 1:4. After gasifying with CO2, tubes were incubated at 39 ˚C. After 48 h of fermentation, 6 mL of 20% HCl solution and 5 mL pepsin solution were added and the incubated for 48 h, simulating post-ruminal degradation. After incubation, the residual substrates of each tube were filtered and used to determine digestibility of DM and NDF. The obtained data were analyzed in a completely randomized design using the General Linear Model (GLM) procedure of SAS software, version 9.1. The Duncan multiple range test was used to compare means at P< 0.05. Result and The results showed that no significant difference between treatments was observed in gas production potential of wheat straw, but gas production potential of soybean meal with rumen fluid of animals fed with myrtle leave after 96 hours’ incubation (158.13 mL/hour) increased (P<0.05). The gas production rate of wheat straw and soybean meal increased by myrtle leave (P<0.05). Fermentation characteristics (partitioning factor, truly digested organic matter and microbial biomass) of wheat straw were not affected by experimental treatments, but the partitioning factor, truly digested organic matter and microbial biomass of the soybean meal in animals fed with myrtle leave was higher in compared with control treatment (P<0.05). On the base of second experiment, using different levels of myrtle essential oils in diet significantly reduced gas production potential and rate and truly digested organic matter in comparison to the control treatment but PF significantly increased (P<0.05). Other parameters did not affect by levels of myrtle essential oils. It seems the inhibitory effect of essential oils on rumen microbial fermentation and decrease of digestion and gas production because of high content of active matters of essential oil in compared with myrtle leave, but increasing of gas production by inclusion of leave in diet refer nutrient availability of myrtle leave for microorganisms. The researchers reported cineole, alfa-pinen and tannins of myrtle essential oils caused to inhibition of microbial enzymes and decrease fermentation. Tannins can reduce microorganism adhesion to nutrients, inhibit microbial activity which have negative effects on fermentation and methane production. According to the result, it appears that inclusion 0.4 % myrtle leave in diet increased gas production and digestibility of NDF in Arabi sheep. But, myrtle essential oils levels significantly reduced gas production, fermentation and digested organic matter.

This research was conducted to investigate the effect of processing sesame straw with low steam pressure, sulfuric acid and enzyme mixture on digestibility and ruminal fermentation, protozoa population, rumination and some blood parameters of Arabi sheep. Twelve sheep were fed with control diet (without sesame straw), diet containing sesame straw processed with 2.4 % sulfuric acid and low steam pressure at 130 °C for 120 minutes and 3 gr/kg DM enzyme, diet containing sesame straw processed by sulfuric acid and enzyme and diet containing sesame straw processed with water. The dry matter and organic matter intake, daily gain, feed conversion, apparent digestibility of dry matter, organic matter, NDF and ADF did not differ between treatments.The processing did not affect ammonia nitrogen, pH, and rumen protozoa species of sheep. Chewing, rumination and resting times were different between treatments and the greatest rumination time (491.67 minutes per day) was for processing with acid and enzyme (P