Study on Bovine Mastitis under Different Management in Pastoral and Agro-Pastoral Areas of Borana Zone, Southern Ethiopia

Introduction

Ethiopia has the largest cattle population in Africa, which is estimated at 53.99 million animals of which 7.2 million are primarily held for milk production [1]. Despite these large numbers, milk production often does not satisfy the country’s requirements due to a multitude of factors amongst which the occurrence of mastitis has great prominence. In terms of livestock population, Ethiopia has the largest population of any African country. Furthermore, cows represent the largest population of cattle production of the country. However; milk production often does not satisfy the countries requirement. According to the reports of [2] the total annual national milk production from cattle, camel and goat in Ethiopia was reach 3,031,860 metric tons raw milk, Out of the total national milk production cows produce 2,411,291 metric tons. However, this amount is by far below the national demand for milk and milk products in the country, given the considerable potential for small holder income and employment generation from high value dairy products. Development of the dairy sector in Ethiopia can contribute significantly to poverty alleviation and nutrition in the country [3].

Mostly in Ethiopia, Cows are kept to provide milk primarily for household consumption and reproduce for production of draught oxen and replacement heifers. Surplus milk is sold, usually by women, who use the regular cash income to buy household necessities or to save for festival occasions [4]. Generally, Milk and milk products play a very important role in feeding the rural and urban population of Ethiopia and have a high nutrition value and is daily produced, sold for cash. It is a cash crop in the milk-shed areas that enables families to buy other foodstuffs, contributing significantly to the household food security [1].

Milk is one of the most important livestock products among the pastoralists in the Borana pastoral communities. It is the main diet for pastoralists [5]. Nevertheless the quality and quantity of milk in the country deteriorates due to various causes. Mastitis imposes a serious problem cause reduction in milk production and remains one of the most economically important diseases for the dairy industry worldwide irrespective of the species of animals [6]. Mastitis is the inflammation of the mammary gland that has over 130 different isolated causative agents from mastitis milk samples but Staphylococcus aureus, Streptococci, and members of the Enterobacteriaceae are among the most common etiological agents in cows and in other animal species [7]. Mastitis can cause devastating effects to farmers because of the serious economic losses and the danger that the bacterial contamination of milk from affected cows may render it unsuitable for human consumption. It is often classified as subclinical or clinical depending on the severity of the disease or contagious and environmental based on the causative agents [8]. The occurrence of mastitis depends up on the complex interaction among three factors; host, agent and environment. Hence, any mastitis control program must be designed towards correcting mastitis problem associated with three epidemiological components [9].

The study area is one of the most known pastoralist area in the country in which milk is primary purpose cattle production and potential area, but less considered. Therefore, the present study is designed to determine the prevalence of bovine mastitis under different management in Borana zone, assess mastitis occurrence with some associated potential risk factors in study area and to isolate and identify major etiological agents of clinical and sub clinical mastitis in study area.

Data Analysis

Data collected from field and laboratory result were entered and stored in microsoft excel spread sheet, screened for proper coding and errors and transported to statistical software for analysis. For the statistical analysis SPSS version 20 and chi-square (x2) test were used. Disease associated risk factors with a P-value less than 0.05 were considered significant.

Discussion

The present result in study area revealed an overall prevalence of 47.4% at cow level and 21.48% at quarter level. This result relatively agrees with prevalence of 52.78% around sebeta and 44.78 in sidamo zone reported by sori, et al. [12] and Yibrah Tekle and Tsega Berihe respectively.

Prevalence of this finding was found lower than finding of wubishet, et al. [13] in selected districts of Borana Zone, bedane, et al. [14] in yabello district and Tesfaheywet Zeryehun and Gerema Abera [15] of Eastern Harrarghe Zone reported the prevalence of 70.8, 59.1 and 64.3% respectively. However, the current finding was higher than prevalence of 7.2%, 8.7%, 11.1% and 24.5 % reported by Nesru, et al. [16] in central Ethiopia, in and around Addis Ababa, [17] around Mekelle and Kefele and Biruk [18] from Wolayta Soddo respectively.

The present study also showed prevalence of 12% for clinical mastitis was closer to 12.5% and 12.4%, reports of Tesfaheywet and Gerema [15] in Eastern Harrarghe Zone, and wubishet, et al. [14] in selected districts of Borana zone respectively. However, it was higher than that of Bishi [16] who reported the prevalence of 5.3%, in Addis Ababa Ethiopia and Tolosa, et al. who recorded the prevalence of 9.5% at Wolayta Soddo. The prevalence of, 25.1% 16.11% and 30.17% were also reported by Workineh, et. al. Hundra, et al. and Hasen, et al. [19, 20] respectively in and around Addis Ababa, and Bench maji south west Ethiopia, that was higher than the current finding. The difference in results could be due to difference in management system between husbandary practices.

Occurrence of subclinical mastitis was found high when compared to clinical mastitis. The prevalence of subclinical mastitis based on CMT test in the present study was (35.4%), which is in close agreement with (38%) the reports done by Bedane, et al. [14] in the same area. It was lower than report of Tesfaheywet and Gerema [15] that was 51.8% and Jirata and Indalem [21] was reported 61.19%. However, the present report is higher than 26.9% and 19.6 % reports of Mulugeta and Wassie, and Kefele and Biruk [18] respectively.

The quarter level prevalence of mastitis in the present study was 21.48%, out of 3% were clinical and 18.48% were subclinical. This result is far lower than findings of 62.3% at Addis Ababa [22] and 47.52% at Addis Ababa and Sebeta Town [23]. Similarly, Mekibib, et al. [24] reported an overall prevalence of 44.9% around Holeta Town, where 10% and 34.8% represent prevalence of clinical and subclinical mastitis.

However, prevalence recorded in the current study is higher than finding of Haftu, et al. 15.4 %; from which, 11.9 subclinical form and 2.4 % were of clinical form and report of Bitew, et al. [25] (12.3%) infection of sub clinical mastitis. The finding of 3.5% blind teat in this study is in agreement with the previous reports 3.32% of Lakew, et al. [26] and higher when compared with the report of Haftu, et al. and Bitew et al. of which 1.1 % and 1.9% respectively. However this result was lower than report (6.6%) of Tesfaheywet and Gerema Abera [15].

The difference may be due to greater experience in drying off, the potential effect of level of milking hygiene, herd size and cleanness, and the application of sanitary measures. With regard to prevalence of mastitis in each quarter of the udder, the left hindquarters were affected with the highest infection rate 7.4%. The right hindquarters were the second with an infection rate of 5%. Zeryehun, et al. [22] attributed the highest infection rates in these quarters to the high production capacity of the rear quarters and the high chance of getting fecal and environmental contamination.

Association of mastitis occurrence with parity, body condition and lactation stage were found statistically significant (P<0.05). According to the result higher infection in cows in early lactation stage followed by medium and late lactation stages that concurs with previous reports [27]. The early lactation stage infection might be due to the carryover of infection from dry period. In cows most new infections occur during the early part of the dry period and in the first two months of lactation (Radostits et. al., 2007). The increase in prevalence of mastitis with parity reported in the study is comparable with the previous reports [27, 28, 29]. This might be due to the increased opportunity of infection with time and the prolonged duration of infection, especially in a herd without mastitis control program and also an increase for teat injuries [30].

In the present study the causes of mastitis were Staphylococcus aureus (38.06%) followed by streptococcus species (21.29%) and coagulase negative Staphylococcus (19.35%). The high prevalence of S. aureus in this study is in accordance with other workers [20]. High prevalence of S. aureus points to poor milking time hygiene as this pathogen is mainly spread during milking via milkers’ hands and towels [6]. The finding of Streptococcus species was in agreement with Bedane, et al. [14], Fentaye, et al. Kefele and Biruk [18] which were 21.5, 23.5 and 25.49% respectively [31, 32, 33, 34, 35]. The relative isolation of this organism in this study may due to poor milking time hygiene, absence of post milking teat dipping, lack of proper treatment for clinically infected animals and absence culling of non-responding of dry period therapy cows.

Conclusion and Recommendations

Generally, mastitis is one of the complex diseases of dairy cows which involve an interaction between management practice and infectious agent occurring throughout the world. The present study indicated considerable prevalence of the disease with the isolation of major pathogenic microorganisms from both clinical and subclinical mastitis. The disease has also been reported in different parts of Ethiopia with varying prevalence. Inadequate hygienic condition of dairy cow, poor milking method, poor animal health service and lack of proper attention to the health of the mammary gland were important for the prevalence in the study area. The impact of diseases on lactating cows is occurred due to increment of risk factor for infection of mammary glands.

Therefore, based the above conclusions the following point forwarded:

• Preventive and control strategy of mastitis should have established that focusing up on awareness on key factors of mastitis such as good herd management, washing hands before and after milking, preparation of clean towel for each lactating cow and milking of infected cow lastly.
• Standard milking procedure, such as pre and post milking udder washing should be applied to reduce the risk of transmission.
• Regular screening of subclinical mastitis for early detection and treatment, and culling of chronically infected cows should be practiced in ranch and farm.
• To reduce the impact of the disease on milking cows, appropriate control measures targeting to reduce risk of infection should be in place, and awareness needs to be created to pastoralists/agro-pastoralists on the impact of the disease.

Conflict of Interest Statement

I declare that this paper is original and my own work results.