Author(s): Müller FOTSAC DZOUSSE*, Marc K. KOUAM, Roland NANKAM CHIMI, Ashu Michael AGBOR, Ornella Ingrid MBIATCHOUA POSSI, Marvine KEUMEZEU, Boris WAFFO DEFFO, Arouna NJAYOU NGAPAGNA and Florence FONTEH ANYANGWE
Mastitis is the major disease in milking cows causing huge losses to the dairy industry worldwide. It is in view to contribute to the eradication of this pathology that the present study was carried out in cattle farms of the West Region of Cameroon from March 2020 to November 2020. A total of 473 lactating cows of local and improved breeds were screened for mastitis. Screening for clinical and sub-clinical mastitis was based on the observation of clinical signs and on the use of the California Mastitis Test (CMT) respectively. The overall prevalence was 34.88%, among which 9.72% and 25.16% represented clinical and subclinical mastitis respectively. In summary, the factors influencing the occurrence of mastitis were: the divisions surveyed (p<0.001), breed type (p=0.003), age range (p<0,001), farm type (p=0.05), soil type (p<0,001), cleaning frequency (p<0.001), feeding method (p<0.001), hygiene of udder (p=0.05) and stage of lactation (p=0.02). The results obtained allow us to recommend an improvement of the breeding conditions to prevent mastitis, because once mastitis appears in a farm, it becomes very difficult to eradicate it
Cameroon’s cattle population is estimated at 5,770,179 head [1]. However, local milk production remains marginal, barely sufficient for calf feeding and self-consumption by farmers [2]. The profitability of this production depends on the control of feeding and certain pathologies, in particular mastitis [3]. Mastitis is the most important health and economic concern of dairy farms worldwide [4]. They are defined as common udder disorders of infectious, traumatic or toxic origin, characterised by a reduction in milk quality and yield, very often with a deterioration in the animal’s general condition, leading to the early culling of the cow [5]. Depending on the clinical signs that may or may not be perceptible, two types of mastitis are frequently encountered in dairy production namely clinical and subclinical mastitis. The consequences of mastitis in cows include a drop in the overall production level of the animals, unfit milk for human and calf consumption, deterioration of milk quality both nutritionally, microbiologically and physicochemically[6]. Mastitis is also a gateway for other opportunistic germs that are harmful to the health of livestock [6]. Economically, mastitis causes direct costs related to veterinary fees, or milk disposal, as well as indirect costs such as reduced fertility, increased risk of culling and sometimes death of the animal [7]. The impact and importance of this disease in dairy farming has motivated numerous studies on its prevalence in Africa. In Senegal, a study of 101 lactating cows in traditional farms in the peri-urban area of Kaolack revealed a prevalence of 11.9% and 10.9% by the Californian Mastitis Test (CMT) and the Somatic Cell Count (SCC) respectively [4]. A study conducted in 2009 in Holeta, Ethiopia on 107 lactating cows reported a prevalence of 71% [9]. To our knowledge, few studies have been conducted on mastitis in Cameroon. The most recent one was carried out in the Adamaoua region in 2018 on 240 local and improved cows, which yielded a prevalence of 68.3%, of which 60% were subclinical mastitis and 8.3% clinical mastitis [10]. Therefore the objective of this work was to determine the prevalence of mastitis and to evaluate the factors associated with its occurrence in cattle farming in the Western Region of Cameroon.
This is a cross sectional descriptive study carried out between March and November 2020 in all the 08 divisions (Figure 1) of the Western Region of Cameroon. The study was carried in the Bamboutos, Haut-Plateaux, Haut-Nkam, Koung-Khi, Menoua, Mifi, Nde and Noun divisions
The Western region is the most densely populated province (126 inhabitants/km2 ) of Cameroon. As at 2019, its cattle population was estimated at nearly 120,000 head comprising all breeds, sexes and ages combined with a milk production of about 270 tonnes that same year[11].
Figure 1: Study area (Western Region of Cameroon)
The study population consisted of lactating cows of local and improved breeds. The minimum size of 333 cows was determined according to the formula:
where N is the estimated sample size, d is the absolute precision at 5%, p is the known or attributed prevalence[12]. This prevalence was 68.3%, obtained from the work of Ngungwa et al., in the Adamawa region of Cameroon. Eventually, a total number of 473 lactating cows were sampled[10]. Inaccessible herds were excluded from the study. All other herds and farms registered or not with the Ministry of Livestock, Fisheries and Animal Industries (MINEPIA) were considered for the study
Clinical mastitis was diagnosed by visual examination and palpation using the method previously described by Quinn et al, and Radostits et al, [13,14]. Briefly, the technique consists of observing the conformation of the different udder quarters, in order to detect any abnormalities in symmetry, volume, colour, skin growths or lesions. Then each udder quarter was palpated individually with the aim of identifying areas that are sensitive to touch. Finally, the milk secretion was examined to assess the colour, smell, consistency, viscosity and homogeneity.
Subclinical mastitis was diagnosed using the CMT test. Manufacturer’s instructions for the CMT Kit - DeLaval was strictly followed as follows [15].After the milk was collected in the CMT plate, the excess milk was poured out and about 3ml of milk from each quarter was kept in the cups of the plate. Subsequently, 3ml of DeLaval reagent was added to each cup and a circular motion was imparted to the plate for a few seconds (15) to mix the milk and reagent. Then the fluidity of the mixture was assessed by tilting the paddle. The results of the CMT test were interpreted on a 5-point scale (negative, 1+, 2+, 3+ or 4+). Positive samples had a score of ≥ 2+. Thus, quarters diagnosed as positive were defined as CMT positive and the cow considered as mastitis carrier. Only animals declared negative on clinical examination were subjected to CMT test.
The collected data were analysed using the statistical software SPSS version 25. Chi-square test (X2) at 5% level was used to compare different prevalence [16]. The value of p ≤ 0.05 was considered statistically significant.
Out of a total of 473 cows screened in the Western region of Cameroon, the overall prevalence of mastitis was 34.88% (165/473). The share of clinical mastitis was 9.72% (46/473), against a prevalence of 25.16% (119/473) for subclinical mastitis (table I). This indicates the poor general hygiene of the farms visited. The dominance of subclinical mastitis could be explained by the fact that this mastitis re silent and very often detected late, contrary to clinical mastitis that are visible, detectable and therefore makes its early management possible. This result is two times lower than the overall prevalence obtained by Ngungwa et al. in the Adamawa region of Cameroon. Indeed, these authors found a prevalence of 68.3% after screening 240 local and improved cows, of which 60% represented subclinical mastitis and 8.3% clinical mastitis [10]. Also, the prevalence values obtained in different regions of the Cameroon’s Western region varied significantly from one division to another (p< 0.001). This could be explained by the uneven distribution of cows screened in these divisions.
Table I: Overall prevalence of mastitis and prevalence per division of the West Region of Cameroon
| Type of Mastitis | BT (N=59) | HP (N=86) | HN (N=32) | KK (N=78) | MN (N=68) | Mifi (N=4) | Nde (N=73) | Noun (N=73) | Total (N=473) | X2 (p-value) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | n | % | n | % | n | % | n | % | n | % | ||
| Clinical | 2 | 3.39 | 6 | 6.98 | 6 | 18.75 | 11 | 14.10 | 2 | 2.94 | 0 | 0.0 | 6 | 8.22 | 13 | 17.81 | 46 | 9.73 | 0.01* |
| Sub-Clinical | 14 | 23.73 | 19 | 22.09 | 6 | 18.75 | 15 | 19.23 | 17 | 25.0 | 0 | 0.0 | 18 | 24.66 | 30 | 41.10 | 119 | 25.16 | 0.004* |
| Total | 16 | 27.12 | 25 | 29.07 | 12 | 37.5 | 26 | 33.33 | 19 | 27.94 | 0 | 0.0 | 24 | 32.88 | 43 | 58.91 | 165 | 34.88 | < 0.001** |
N= Number of cows in lactation; n = Number of cows with mastitis; % = Prevalence of mastitis; * = Significant difference at 5% level; ** = Very significant difference at 5% level; BT = Bamboutos ; HP = Hauts Plateaux ; HN = Haut Nkam ; KK = Koung-Khi; MN = Menoua ; X2 = Chi-square.
Regarding the types of breeds found in the West region herds, a significant difference (p=0.003) was observed between the prevalence of mastitis in both local and improved breeds. Indeed, the prevalence of mastitis in improved cows (62.07%) was much higher than that observed in local breeds (33.11%) (Table II). This could be explained by the fact that almost all the improved cows were high performance dairy cows (Holsteins), which are prone to mastitis compared to the local cows which constituted the majority of our study population [17]. These results are in agreement with that of Hamlaoui, who found in a study conducted in the Willaya of Constantine, that improved breeds more precisely Holstein was more predisposed to develop subclinical mastitis than local breeds [18].
Table II: Prevalence of mastitis by breed type
| Type of Mastitis | Locale Breed (N=444) | Improved Breed (N=29) | X2(p-value) | ||
|---|---|---|---|---|---|
| n | % | n | % | ||
| Clinical | 44 | 9.91 | 2 | 6.90 | 0.9 |
| Sub-Clinical | 103 | 23.20 | 16 | 55.17 | < 0.001** |
| Total | 147 | 33.11 | 18 | 62.07 | 0.003* |
N= Number of cows in lactation; n = Number of cows with mastitis; % = Prevalence of mastitis; * = Significant difference at 5% level; ** = Very significant difference at 5% level; X2 = Chi-square
In addition to the divisions of the West Cameroon region and the breed type, several other parameters significantly influenced the occurrence of mastitis in cattle farms in the West Cameroon region (Table III). In Other words, the age of the cows, the type of farm, the nature of the soil, the frequency of cleaning of the barn, the feeding method, the cleaning of the udders and the stage of lactation were all statistically significant (p< 0.05).
The prevalence of mastitis was higher in cows older than 7 years (54.34%). In fact, according to a study conducted by Poutrel (Poutrel, 1983), the frequency of both udder infections and clinical mastitis increases with age or more precisely, increases with the number of lactations of the animals. Therefore, culling of cows older than 7 years could be a solution to this problem. Also, the prevalence of mastitis was much higher in modern farms (61.54%) than in traditional farms (34.13%). This could be explained firstly, by the uneven distribution between the types of farms under study and secondly, by the totality of the exotic farms which consisted of dairy cows, which are more prone to develop mastitis. The nature of the barn floor, especially cement and plank floors, was strongly associated with mastitis (p< 0.001). This could be explained by the fact that on these farms, with cement and plank floors, the breeds found were once again improved dairy breeds with a strong tendency, or more likely to develop mastitis. Moreover, the presence of these improved breeds significantly influenced the occurrence of mastitis with high prevalences in farms with daily cleaning frequency (69.57%), stall feeding (69.57%) and udder washing with warm water (52.94%). These three factors have in common the dominant presence of improved cows. However, the high prevalence in farms with daily cleaning frequency (+/- modern farm) could be corrected by cleaning twice a day to keep the stall air clean and dry. This hygiene will limit the occurrence of environmental mastitis by reducing the occurrence of favourable factors such as dirty udders and damaged teats.
Table III: Factors associated with the occurrence of mastitis in cattle farms of the West Cameroon region
| Associated Factors | N (= 473) | n | % | X2 (p-Value) |
| Origin / Division | < 0,001** | |||
| Bamboutos | 59 | 16 | 27,12 | |
| Hauts Plateaux | 86 | 25 | 29,07 | |
| Haut Nkam | 32 | 12 | 37,5 | |
| Koung-Khi | 78 | 26 | 33,33 | |
| Menoua | 68 | 19 | 27,94 | |
| Mifi | 4 | 0 | 0,0 | |
| Nd | 73 | 24 | 32,88 | |
| Noun | 73 | 43 | 58,91 | |
| Breed | ||||
| Local | 444 | 147 | 33,11 | 0.003* |
| Improved | 29 | 18 | 62,07 | |
| Age range/year | ||||
| ] 3; 5] | 192 | 53 | 27,6 | < 0.001** |
| ] 5; 7] | 235 | 87 | 37,02 | |
| >7 | 46 | 25 | 54,34 | |
| Type of farm | ||||
| Modern | 13 | 8 | 61,54 | 0,05* |
| Traditional | 460 | 157 | 34,13 | |
| Soil nature | ||||
| Cimented | 20 | 10 | 50 | < 0.001** |
| Ground | 442 | 149 | 33,71 | |
| Wood | 11 | 6 | 54,55 | |
| Frequency of Barn cleaning | ||||
| Daily | 23 | 16 | 69,57 | < 0.001** |
| Monthly | 33 | 13 | 39,39 | |
| Occasionally | 115 | 53 | 46,09 | |
| Never | 302 | 83 | 27,48 | |
| Nutrition mode | ||||
| Vain pasture | 450 | 149 | 33,11 | < 0.001** |
| In stalls | 23 | 16 | 69,57 | |
| Udder washing | ||||
| Yes with warm water | 34 | 18 | 52,94 | 0,01* |
| Yes with cold water | 106 | 41 | 38,68 | |
| No I don't wash | 319 | 103 | 32,9 | |
| No response | 14 | 3 | 21,43 | |
| Lactation stage | ||||
| 0 to 3 months | 1 | 1 | 100,0 | 0,02* |
| 4 to 10 months | 232 | 63 | 27,16 | |
| >10 months | 135 | 54 | 40,0 | |
| No Idea | 105 | 47 | 44,76 | |
N= Number of cows in lactation; n = Number of cows with mastitis; % = Prevalence of mastitis; * = Significant difference at 5% level; ** = Very significant difference at 5% level; X2 = Chi-square
The aim of this study was to determine the prevalence of mastitis and the factors influencing its occurrence in cattle farms in the Western Region of Cameroon. Indeed, this disease is the greatest world health and economic concern in dairy farms. Therefore, an accurate knowledge of the epidemiological data on cattle mastitis would help to create a better mastitis control program in Cameroon, where most of the efforts are concentrated on the treatment of clinical cases. Also, according to the results obtained, the prevalence of subclinical mastitis is much higher than that of clinical mastitis, which means that early detection techniques of these mastitis in farms should be considered, using CMT, which is reliable, quick, simple and effective. This is to ensure effective management of sick cows and improve milk production in Cameroon.
The study was conducted without any conflict of interest.
