مجله تولیدات دامی
سال بیست و پنجم شماره 2 (تابستان 1402)

Mastitis is one of the most frequent and costly diseases of the dairy cattle industry and causes many economic losses, which negatively affects milk yield and composition, fertility, longevity and welfare of cows. The best solution for reducing the economic and biological consequences is early and accurate prediction of mastitis based on indicator factors. So far, various statistical methods have been used to predict mastitis such as linear and multiple regression, and threshold models. Machine learning is another method that has recently widely been used to predict farm profitability, reproductive traits, longevity and abortion in dairy cow. Machine learning is defined as a set of methods for automatically finding patterns in data and then using those patterns to predict possible future data.

In this research, the performance of four machine learning algorithms including random forest, decision tree, Naïve Bayes and logistic regression and two sampling methods, over-sampling and under-sampling, were compared to predict risk of clinical mastitis based on data collected in two Holstein dairy herds in Isfahan province. Final dataset included 393504 records on cows calved during 2007 to 2017 of which 13653 cases (3.47%) were infected and 379851 cases (96.53%) were healthy. Factors related to mastitis, including parity, daily milk production, calving

The selection of animals by humans left detectable signatures on the genome of modern goat. The identification of these signals can help us to improve the genetic characteristics of economically important traits in goat. Over the last decade, interest in detection of genes or genomic regions that are targeted by selection has been growing. Identifying signatures of selection can provide valuable insights about the genes or genomic regions that are or have been under selection pressure, which in turn leads to a better understanding of genotype-phenotype relationships. A run of homozygosity (ROH) is a consecutive tract of homozygous genotypes in an individual that indicates it has inherited the same ancestral haplotype from both parents. Run of homozygosity one of the most methods were used to detecting the genomic inbreeding. The locations of ROHs which are under positive selection, or laboring favorable allele in population, tend to be fixed in the genome and formation of ROH Island during long times. Genomic regions enriched with ROH may be indicative of selection sweeps and are known as ROH islands. As detecting the ROH Islands, the genomic regions contain economic traits could be detectable.

In this research, the amount of genomic inbreeding and the effective size of the population were investigated using the information obtained from 879 goats of different breeds including Beetal, Daira Deen Panah, Nachi, Barbari, Teddi, Pahari, and Pothwari. In order to determine the genotype of the samples, Illumina caprine Bead Chip 50K were used. The genomic information of goat breeds was extracted from the figshare database. Quality control was conducted using the Plink software. The markers or individuals were excluded from the further study based on the following criteria: unknown chromosomal or physical location, call rate <0.95, missing genotype frequency >0.05, minor allele frequency (MAF) < 0.05, and a P-value for Hardy–Weinberg equilibrium test less than 10-3. After quality control, 36,861 SNPs from Goat SNP chip 50K on 827 goats were remained for the future analysis. Inbreeding coefficient was calculated using four methods including, genomic relationship matrix (FGRM), excess of homozygosity (FHOM), correlation between uniting gametes (FUNI) using the GCTA 1.0 software and run of homozygosity (FROH) using the PLINK 1.9 software. The effective population size (Ne) was calculated from linkage disequilibrium data with SNeP software (version 1.1). GeneCards (http://www.genecards.org) and UniProtKB (http://www.uniprot.org) databases were also used to interpret the function of the obtained genes.

The lowest and highest inbreeding coefficient calculated by three methods (FGRM, FHOM, and FUNI) were related to Beetal and Barbari breed, respectively. The highest (0.159) and lowest (0.028) amount of FROH was estimated in the Barbari and Pothwari breeds, respectively. The average length of ROH ranged from 70.2 to 391.4 Mb, and the average number of ROH fragments varied between 8.19 and 48.65. Also, the highest and lowest number of ROH were observed on chromosome 2 and 29, respectively. The size of Ne in in the current generations (fifth generation) of the studied breeds was ranged from 35 to 365. The highest Ne was estimated in the Beetal breed (365 heads) and the lowest in the Barbari breed (35 heads). The average inbreeding coefficient in Beetal, Teddi, Pahari, Nachi, Barbari, Daira Deen Panah and Pothwari breeds was obtained 0.035, 0.081, 0.031, 0.052, 0.15, 0.11 and 0.02, respectively. In addition, the Ne of most of the studied populations has been decreased. The results of this study revealed that, the selection processes in different goat breeds for economic traits during several years, has led to the formation of many ROH islands in goat genome, therefore scanning these regions at the genome level can be an alternative strategy to identify genes and associated loci with economic traits.

our findings contribute to the understanding of genetic diversity and population demography, and help design and implement breeding and conservation strategies for study goat breeds. Therefore, it is necessary to economize production and planning a suitable mating scheme to control inbreeding and genetically conserve the remaining pure animals of these breeds.

The production of dairy goat breeds such as Saanen has become widespread in many countries and factors like the nutritional value of goat milk, high amounts of milk yield compared to body weight, and less methane gas production have played important role for the mentioned development. Previous studies have shown that reaching the insemination weight (35 kg) of replacement female goats is one of the most important points in the breeding of the dairy goat breeds. Subsequently, other studies have shown that improving growth and weight gain during suckling period reduces the time to reach the required weight and body size for insemination, the growth of mammary glands and increases milk production, and it is economically important. Protein is one of the factors which play important role in growth and body frame development of goats especially at life's early stages. Therefore, the aim of the present study was to investigate the effects of different levels of crude protein in milk replacer on performance of Saanen suckling kids. Sixteen Saanen female kids with 10 days of age and 4.678± 0.57 kg of BW were randomly assigned to two experimental treatments, including milk replacer with 22% crude protein (22CP; milk replacer contain 22% crude protein) and milk replacer with 28% crude protein (28CP; milk replacer contain 22% crude protein plus 10 gram of whey protein concentrate per liter of milk replacer). The experimental kids were weaned at 64 days of age and during this time milk replacer, starter, and alfalfa hay intake of kids was recorded daily, and the weight of the goats was measured weekly. The results showed that average daily weight gain of kids fed with 28CP treatment was significantly higher (P < 0.05) compared to the 22CP treatment during the first month, the second month and whole experimental period. Also, the kids body weight at the end of second month for 28CP treatment was significantly higher (P = 0.05) compared to the 22CP treatment (16.14 vs. 14.21 kg).  The amount of total dry matter intake (DMI) during the entire experimental period was higher (P < 0.05) for the 28CP treatment compared to the 22CP treatment (509.65 vs. 459.68 grams per day). There were no significant differences among the experimental treatments for the feed conversion ratio (FCR) during the first month, the second month and the entire experimental period. In fact, although the 28 CP treatment had a higher daily weight gain compared to the CP22 treatment, due to higher DMI, but it had a similar FCR compared to the CP22 treatment. Results showed that feeding milk replacer containing high levels of crude protein (28%) can results to the higher average daily gain and subsequently heavier weaning weight in Saanen goat kids.

Efficient management methods should be used to achieve optimal production of livestock products in breeding, reproduction and feeding stages. If proper nutritional management is not performed correctly at the end of pregnancy, it will have adverse effects on the amount of dry matter intake and the metabolic condition of the animal during early lactation. In all animal tissues, there are variable proportions of mineral elements and vitamins; the concentration of these elements must be within the specified range in order to protect the functional and structural activity of the tissues and to keep the growth, health and productivity of the animal without reduction or damage.

In order to evaluate the effects of selenium and vitamin E supplements administered orally or by injection in late pregnancy on the concentration of selenium, copper, zinc and iron in the blood and milk of ewes and the blood of their lambs this experiment were conducted using 18 pregnant ewes of the first lambing in a completely randomize design with three treatments and six replications. Experimental treatments included: 1) Control (receiving a dose of 10 ml of selenium and vitamin E supplement by injection two weeks before delivery; each ml contains 0.5 mg of sodium selenite and 50 mg of vitamin E). 2) selenium and vitamin E (receiving 0.3 mg of selenium and 50 mg of vitamin E mixed with diet daily per kilogram of dry matter intake) orally from four weeks before delivery and, 3) Injection of 10 ml selenium and vitamin E supplement in two stages including four weeks before calving (five ml) and two weeks before calving (five ml).The Blood samples were collected from the ewes before the administration of supplements and at the time of delivery. Blood was collected from newborn lambs before consuming colostrum and 14 days after birth. Selenium, copper, zinc and iron concentrations were measured in colostrum and milk.

The results of the experiment indicated that the average weight of the ewes two weeks after lambing for ewes that received selenium and vitamin E orally was higher than the control (P<0.05). No significant difference was observed in the concentration of iron, copper and zinc in the blood serum of ewes or lambs. The concentration of selenium in the serum of ewes and their lambs and the colostrum of ewes that received selenium and vitamin E orally was higher than other ewes. No significant difference was observed between the experimental treatments in terms of the average body condition score (BCS) until the time of delivery, but two weeks after delivery, BCS in the orally supplement of selenium and vitamin E treatment was higher than that of control group.

The results of the present study showed that in order to improve the status of selenium in livestock and the convenience of supplement administration, the use of orally selenium and vitamin E supplements is preferred by its injection method.

Increased livestock production can be achieved through the cultivation of high-quality forages with high-yielding capacity. Napier grass has been introduced to all tropical and subtropical areas of the world and is used as a forage crop with high potential productivity in terms of annual dry matter yield. However, both dry matter yield and nutritional quality of this grass have been affected by different cutting interval. This grass has been neither grown nor studied as a source of forage for ruminant nutrition in Iran.This research was conducted to identify the appropriate cutting interval for Napier grass to produce the maximum nutritive value and yield. Napier grass was cultivated in a complete randomised block design with three replicates. During the growth season, the cutting intervals were 16-20, 24-28, 43 d or 136 d after planting to corresponding cutting heights of 50, 100, 150 and 300 cm. Hence, from each plot 6, 4, 2, or 1 cuts were harvested, respectively. Cell wall fractions, organic matter, and crude protein of Napier grass from different cuts were determined. Dry matter and organic matter digestibility and in-vitro ruminal fermentation kinetics of the forages were also determined. Biomass production of Napier grass under different cutting interval programs was also assessed. The highest yield of dry matter of Napier grass (25.1 tons per hectare) was observed when only one cut was harvested at the end of vegetative stage (height of 300 cm). The digestibility of organic matter (OMD) ranged from 60 to 70 % in all treatments and the highest OMD was observed at the height of 50 cm. The maximum dry matter and digestible organic matter per hectare (15.9 and 14.2 tons, respectively) was produced when forage was harvested in one cut at the height of 300 cm. There was no difference in the yield of digestible dry matter and digestible organic matter of the forage harvested at the height of 50 and 100 cm. The concentration of crude protein in forages from different cuts ranged from 7.1 to 14.2 % and neutral detergent fiber ranged 65.7 to 76.2 %. The highest concentration of crude protein and the lowest cell wall components were observed at the height of 50 cm. The lowest and the highest gas production potential and fractional rate of gas production were observed at the cutting height of 300 cm and 50 cm, respectively. The present study showed that it is possible to obtain higher quality of Napier grass by shortening the harvesting intervals. However, this resulted in a pronounce decrease in the yield of organic matter and digestible dry matter yield per hectare. The highest organic matter and digestible dry matter per hectare was produced when Napier grass was harvested only once (136 d after planting and height of 300 cm) at the end of vegetative stage.

Aflatoxins are produced by Aspergillus flavus and Aspergillus parasiticus mold, and aflatoxin B1 is the most dangerous form of this toxin. In addition, aflatoxin B1 in poultry causes low productivity and high sensitivity to diseases and the use of inorganic and organic toxin binders is one of the nutritional strategies to confront aflatoxins. In this research, the effects of adding multi-component toxin binder to diets containing aflatoxin B1 on growth performance, blood parameters, and liver histology by using 180 male broilers day-olds (Ross 308) in a factorial experiment (3×3), with three levels of toxin binder (0.0, 0.5, and 1.0 kg/ton) and three levels of aflatoxin B1 (0.0, 0.5, and 1.0 mg/kg) were studied based on a completely randomized design in nine treatments, four replications, and five chickens in each replicate. The results showed that using the 1.0 kg/ton of toxin binder, significantly reduced negative effects of 0.5 mg/kg of aflatoxin B1 on the average daily weight gain, live weight and average daily feed intake in the total period (P<0.05). But the birds consuming the treatment containing 0.5 mg/kg of aflatoxin B1 and 1.0 kg/ton of toxin binder did not show a significant difference, in the average feed conversion ratio compared to all treatments except the treatment that containing 0.0 mg/kg of aflatoxin B1 and 0.5 kg/ton of toxin binder. The regression equation (Y= 7.5298x+ 53.377) with (R2= 0.78), was obtained to predict the average daily weight gain of birds fed with treatments containing 0.5 mg/kg of aflatoxin B1 and different levels of toxin binder. Feeding chickens with diets containing aflatoxin B1, significantly decreased the serum concentration of cholesterol, albumin, and total protein and increased serum concentration of creatinine and urea (P<0.05). In addition, there were not significant effects for the main and interaction of aflatoxin B1 and toxin binder for the blood serum alkaline phosphatase. For liver histological results, portal inflammation was evident in all treatments, but the amount of fibrosis and necrosis was higher in treatments with 0.5 and 1.0 mg/kg of aflatoxin B1 than 0.0 level of its, and in the liver of birds fed with the highest level of aflatoxin B1 (1.0 mg/kg), micro and macro lipid vesicles were observed, which indicates a fatty liver. Also, some hepatocytes lost their cytoplasm due to the storage of a type of glycogen and in some parts, a proliferation of fibroblasts with fine collagen fibers deposition, was observed. The toxin binder did not prevent of the negative effects of aflatoxin B1 on the destruction of liver tissue. Based on the results, adding 1.0 kg/ton level of multi-component toxin binder to diets containing 0.5 mg/kg aflatoxin B1 can improve the average daily weight gain, live weight, and average daily feed intake of broilers.

Bacteria of the intestinal tract may have a profound impact on lipids' digestion and utilization. The proposed mechanism for reduced lipids digestibility is the de-conjugation of bile salts, via bacterial bile salt hydrolase (BSH) enzyme activity. The activity of BSH is well recognized in some genera of lactic acid bacteria like Enterococci. Bacteriophages are recognized as bacteria-eating viruses, which are host specific in contrast to antibiotics. We find bacteriophages that lysis the laying hen's intestinal Enterococci. It is expected that oral administration of bacteriophage lessens the negative impact of Enterococci BSH activity on lipids digestion.

A total of 240 high-line W-36 laying hens aged 50 weeks were tested in six treatments with five replications and eight pieces in each replication for eight weeks in a completely randomized design. Treatments include, 1) control (basal diet without additives), 2) basal diet + antibiotic (virginiamycin), 3) basal diet + lipid-lowering drug (atorvastatin), 4) basal diet + bile salt powder, 5) basal diet + oral gavage of Enterococcus bacteria, and 6) basal diet + oral gavage of bacteriophage against Enterococcus.

The results showed that the group receiving the lipid-lowering drug (atorvastatin) had significantly the lowest percentage of egg production, the lowest egg mass, and the highest feed conversion rate (P<0.05). Enterococcus bacteria and atorvastatin had the same performance, although Enterococcus bacteria did not increase the feed conversion rate as much as the lipid- atorvastatin, it performed poorly compared to the bacteriophage. The use of phage in poultry improved performance. No significant effect among treatments was observed in albumin, glucose, uric acid, calcium, and phosphorus. The level of cholesterol, triglyceride, total protein, and globulin in the atorvastatin group was lower compared to the antibiotic and bile salt groups (P<0.05). Cholesterol and triglyceride levels were higher in the antibiotic, bacteriophage, and bile salt powder treatments than in the other treatments (P<0.05). The lowest concentration of uric acid was observed in the control group and the highest percentage of hematocrit was observed in the bacteriophage and control groups. The role of antibiotic and bile salt in the rest of the reports was the same as bacteriophage but regarding the increase of hematocrit in bacteriophage treatment, phages showed their superiority in this field (P<0.05). The total number of aerobic bacteria, lactic acid bacteria, enterococcus, and coliforms in the bacteriophage group was less than in the bacteria group (P<0.05). However, the digestibility of crude protein was not significantly different between bacteriophage and bacteria groups (P<0.05). The total population of aerobic bacteria was lower in antibiotic and bacteriophage treatments. This study demonstrated the ability to use bacteriophage to reduce the population of specific bacteria. The population of lactic acid bacteria was higher than other treatments in bacteria treatment. Bacteriophage had been more effective to reduce the population of Enterococcus bacteria than other treatments. A close competition between antibiotics and bacteriophage was observed. Regarding the reduction of the E.coli bacteria population, it showed the appropriate ability of bacteriophage to replace the antibiotics. The digestibility of ether extract and dry matter in the bacteriophage was higher than in the bacteria group. The dry matter digestibility in antibiotic and bacteriophage is similar, but bile salt powder was not similar to bacteriophage in this case, and the dry matter in bile salt powder was the lowest (P<0.05).

Based on the results, oral bacteriophage could improve dry matter digestibility and reduce the Enterococcus bacteria population without a significant impact on production performance in laying hens.

Performance appraisal is the most important focal points of production units. In this study, the Casual Comparative approach applied to measure the performance of active poultry units in Zanjan province. Among the various performance measurement models, total productivity index of Malmquist Index was selected because of its greater effectiveness in measuring growth. In order to achieve a comprehensive model, all poultry farms in Zanjan province were considered for study; However, due to the lack of data required, only 30 poultry farms were selected for performance evaluation. In this study, the amount of initial hatching, feed consumption, energy costs, personnel costs and healthcare costs were selected as input variables and final slaughter weight and fertilizer weight were selected as output variables. Specialized software GAMS.34.1.0 and DEA SOLVER (V8) were used for data analysis. The result showed that among the existing decision units (DMUs), in the first period AL12 with 34.9% growth had the highest total productivity growth and AL14 with a decrease of 14.4% Has had the highest productivity decline. Meanwhile, AL14 with the changes in the method of feeding poultry in the second period has had the highest growth of total productivity. On the other hand, although the AL12 unit has had the highest growth in the first period, but due to lack of attention to costs Energy and non-optimal use of grain consumed in the second period are classified as low-growth decision-making units.

Analyzing technical efficiency is particularly important in any economic sector, including the livestock industry and broiler production. By analyzing the efficiency of units, it is possible to help improve the use of resources and increase domestic production. Given the special importance of the livestock and broiler production industry in the country, it is necessary to analyzing technical efficiency and optimizing production in this area. Especially in Kurdistan province, which is one of the most important regions of broiler production in the country (3.8% of production in 2020), analyzing the efficiency and optimization of Arian race broiler production can be one of the solutions to increase domestic production and improve the country's economy. The current study aimed to assess the technical efficiency and identify the key determinants affecting the production of Arian broiler chicken in Kurdistan province using a parametric approach known as the Stochastic Frontier production function (SFP) method. 

The level of technical inefficiency within the studied units was estimated by applying the functional form of Translog and employing the maximum likelihood method. A proportional sampling technique was employed to select a sample of 21 broiler farms for the study. The selection of farms was based on a proportionate representation of the target population. Subsequently, comprehensive input-output data were collected through the administration of a structured questionnaire in the year 2021.This function has been estimated using the Ttranslog function form and with the help of the maximum likelihood method, and units have been investigated the main factors explaining the level of technical inefficiency of the studied. A proportional sampling method was used to select 21 broiler farms, and input-output data were collected by completing a questionnaire in 2021.

In this study, using the translog function, has been investigated the relationship between different variables and technical efficiency in the production of Arian broiler in Kurdistan province. The results showed that feed consumption, the number of hatchlings and the cost of medicine and health were important variables that had a direct and significant effect on the amount of meat production. In addition, the estimated technical efficiency at the farm level ranged from 43% to 90% with an average of 75%. This result indicates that the poultry farms of Kurdistan province have relatively high technical efficiency. Also, the evaluation of the factors related to inefficiency showed that among the seven investigated factors, the variables of age, experience of the poultry owner and the labor force, the length of the breeding period and the degree of mechanization of the units had a negative and significant effect on the inefficiency. The age and experience of the poultry owner, there were two of the most important influencing factors that were observed in this research.

Considering the importance of broiler feed in increasing efficiency and its high share of variable costs, measures to stabilize its price are essential. To do this, contract farming may help broiler farmers to reduce price fluctuations in the feed market. Additionally, in case of shortage, the government can intervene and regulate the feed market. Also, considering that the age and experience of the poultry owner are two important factors on production efficiency, designing appropriate training programs for them can help improve their experience and skills in broiler production.