Identification of Abomasum Nematodes Fauna of Ruminants in Kerman Industrial Slaughterhouse, Iran

Introduction: Parasitic diseases play an important role in reducing livestock productions. Particularly, nematode diseases have a determining role in reducing domestic animal products (milk, meat, wool). On the other hand, the most challenging digestive nematodes live in the abomasum. Therefore, the identification of parasitic diseases, especially nematode diseases, is of particular importance. The aim of this study was to investigate and identify the ruminants’ abomasum nematode fauna of infection in the Kerman industrial slaughterhouse in Iran.


Introduction
Like many other countries, ruminates are among major resources of protein for humans and significant in the animal husbandry industry in Iran. The livestock population in Kerman Province, Iran, makes up 5% of the total farm animal population of the country. Parasites and worms of the digestive tract are a major factor decreasing the production of ruminant worldwide [1,2].
Ruminants are the main hosts for parasitic and worm infections, often manifesting themselves in chronic and subclinical forms. Factors affecting parasitic infections include climatic conditions, livestock nutrition, and vegetation [3]. Infection with parasitic worms of the digestive tract may cause complications such as lack of appetite, reduced growth and production, decreased livestock products, stopped skeleton formation and, as a result, reduced absorption of nutrients, leading to reduced livestock weight and decreased production of meat and livestock products.
Moreover, the absorption of minerals and some enzymes is decreased. Also, the weight of calves born of livestock infected with nematodes of the digestive tract and abomasum is lower than that of healthy livestock, and they are more prone to different diseases. If infection is severe, it leads to heavy loss in the livestock [4,5]. Abomasum is a major organ for nematodes. The most Studies have indicated a considerable difference in the type of ruminant worm infection in different organs. It is necessary for worm infection control and prevention programs be developed in different regions based on the data collected from the same region [7]. The present study aimed to determine the level and type of abomasum worm infection in Ruminant slaughtered in the industrial slaughterhouse in Kerman, Iran.

The Studied Geographical Region
Kerman Province is located in Southeastern Iran with a hot, semi-arid, and desert climate. The livestock population in Kerman province makes up about 5% of the total livestock population of the country.

Sampling
The abomasa of the slaughtered livestock were collected

Parasitology Test
Each abomasum was opened and emptied, its surface was washed and scraped in a tub so that nematodes would fall into the tub. The contents of the tub were then poured onto a 100-mesh sieve. Afterwards, the contents were transferred to a 3L container 10 parts of which was previously filled with water. In the next step, the contents were mixed and poured into a Petri dish using a ladle and viewed under a loop with black background under strong light.
Using this method, the worms were viewed under the loop without staining. In another method, the contents of the ladle were poured into a plate, and a few drops of lughole's iodine were added. The worms absorbed the dye and were viewed as red in color. Then, iodine was added so that extra dye would exit the worm. The worms were transferred to 70% alcohol for storage. Unstained worms were lucidified for identification using lactophenol. The identified nematodes were placed on a slide and a few drops of lactophenol were poured on them. The number of separated worms in a ladle was multiplied by 100 to calculate the number of worms in the abomasum [8]. All the separated nematodes were identified based on their appearance (anterior outgrowths, shape, size of spicule, etc.) and a valid identification key.

Statistical Analysis
Results of statistical analysis are expressed in percentage.
The prevalence of nematode infection in the abomasum and the relationship with variables (sex, age, season, and infection) were separately analyzed using Chi-squared test in SPSS 19 at the significance level of p<0.05.

Results
Of the 208 abomasa taken from the studied slaughtered ruminant, 169 (81.25%) abomasa were infected with the nematodes of

Marshallagia, Parabronema, Camelostrongylus, Haemonchus, and
Ostertagia ( Figure 1). Of the identified parasites, the most prevalent nematodes were Marshallagia and Parabronema, and the least prevalent ones were Camelostrongylus (Table 1). Based on the results of Fisher's exact test, the variables of the type of livestock, season, and age of livestock affected infection (p-value<0.05). All livestock were infected, except for 39 cows (75%) aged 2-3 years, whereas no significant relationship was found between sex and parasitic infection ( Table 2).

Discussion
Based on the rising trend in population and the increasing demand for food, especially protein, livestock products are in demand more than ever. Accordingly, it is necessary to fight parasitic infections. Parasitic, and especially worm, infections are a major cause of reduction in livestock products (meat, milk, and wool). Also, parasites predispose livestock to infectious and noninfectious diseases [9,10]. Therefore, the identification of infectious  [12,13].
Moreover, in numerous studies on cows in Europe, the prevalence of abomasum parasite has been reported at 80-90% [14,15]. The high prevalence of nematodes in this and similar studies may be due to the direct evolution and higher resistance of eggs in the environment. In addition, since antiparasitic medications, either preventive or therapeutic, are often used by stockbreeders in an inaccurate and insufficient manner, the potential risk of drug resistance has been reported for some medications [16,17].
In the present study, no significant relationship was found

Conclusion
In this study, the highest level of infection in terms of number belonged to Marshallagia and Parabronema, and the lowest belonged to Camelostrongylus. It seems that despite the use of antiparasitic medications, infection with these nematodes persists, and the existence of drug resistance is probable, especially in case of Marshallagia. Therefore, it is recommended to strategically and scientifically fight these abomasum nematodes.