Influence of mastitis and repeat breeding incidence on participation in the animal insurance program for dairy farmers in Ba Vi, Hanoi, Vietnam

nistered to obtain 
information regarding dairy management and 
hygiene awareness as well as cattle health 
outcomes. Occurrences of mastitis and repeat 
breeding within the previous three months were 
queried for each individual cow. The degree of 
each farm’s sanitation was graded on a scale of 
1-4 (1: cleanest to 4: dirtiest) for three parts of 
each cow: legs, udder, and flank and upper leg 
(Reinemann, 2007). The average score of the 
three parts for all cattle was recorded as the 
farm’s hygiene score. Farmers were also asked to 
rate their level of awareness regarding diseases 
common in cows, including mastitis and repeat 
breeding, using a Likert scale, with 0 indicating 
no problem and 5 indicating a significant 
problem. 
Informed consent was obtained from all the 
farmers participating in this study at the time the 
interview was performed. This study did not 
involve invasive treatments in animals or 
collection of personal information through 
interviews. All interviewing and sampling 
procedures adopted in this study were approved 
by the ethics committee of Rakuno Gakuen 
University, Japan (approval number: 16-8). 
Laboratory examinations 
Causal organisms of sub-clinical mastitis 
were isolated from the collected milk samples. 
Microbial species isolated included coagulase-
Kentaro Koide et al. (2019) 
https://vjas.vnua.edu.vn/ 465 
positive staphylococci (CPS) other than 
S. aureus, S. agalactiae, Escherichia coli, and 
Klebsiella spp. Cows were categorized as having 
sub-clinical mastitis if they presented no 
apparent symptoms but their milk samples were 
positive for bacterial growth. Milk samples were 
streaked on sheep blood agar plates, which 
support the growth of various types of bacteria. 
The plates were incubated at 37°C overnight. 
Three major bacterial colonies on each agar plate 
were selected and sub-cultured on blood agar 
plates. Biochemical tests were used for species 
identification, including the hemolysis, CAMP, 
catalase, and tube coagulase tests. Bacterial 
isolates that produced no hemolysis were 
subjected to biochemical testing for confirmation 
as E. coli or Klebsiella spp. Staphylococcus hyicus 
produces no hemolysis on blood agar, but 
S. aureus, S. intermedius, and S. agalactiae 
exhibit β-hemolysis. Therefore, these bacteria 
were classified based on the catalase test, which 
is primarily used to distinguish gram-positive 
bacteria. The results obtained with the catalase 
and coagulase tests were confirmed by PCR for 
S. aureus species-specific genes using the 
forward primer 5'-GCG ATT GAT GGT GAT 
ACG GTT-3' and the reverse primer 5’-AGC 
CAA GCC TTG ACG AAC TAA AGC-3’ 
(Sasaki et al., 2010). 
Statistical analysis 
Data were digitized in a Microsoft 
Access® Database and analyzed using R 
statistical software (R×64, version 3.0.3) for 
Windows®. The association between 
insurance subscription and the aforementioned 
disease occurrence/ management practices was 
analyzed at the farm level. A farm was denoted 
as positive for mastitis/repeat breeding if at 
least one animal with the problem was reported 
or diagnosed by microbiological testing. These 
occurrences (0 = negative and 1 = positive) 
were used as response variables, and the other 
data collected in the questionnaire were used as 
explanatory variables. Each variable was 
analyzed using the Wilcoxon rank-sum, chi-
square, or Fisher’s exact test, depending on the 
data structure. 
Results 
Farm characteristics 
All of the farms in the study were small scale 
(1 to 22 cows per farm), and 88.7% (86/97) of the 
farms had less than 10 cows. Table 1 shows the 
number of farms, milk samples, and mean herd 
sizes of the insured and non-insured farms. All 
cattle were housed on concrete surfaces. Cattle 
were fed raw grass and purchased concentrate at 
both insured and non-insured farms. There were 
no significant differences between insured and 
non-insured farms in any of the characteristics 
examined (Figure 2). 
Cumulative incidence of clinical mastitis and 
prevalence of sub-clinical mastitis 
In the questionnaire survey, factors related to 
mastitis were investigated using data from 95 
farms, as two farms did not provide information 
regarding the incidence of mastitis in the 
interviews. The three-month cumulative 
incidence of clinical mastitis, calculated from the 
questionnaire survey results, was 22.1% (21/95) 
at the farm level. In addition, at the individual 
level, the incidence was 8.4% (29/344, health 
information regarding clinical mastitis was not 
obtained for 85 cows). 
In the laboratory analyses, the prevalence of 
sub-clinical mastitis was 11.1% (17/153) at the 
individual level, and the prevalence at the farm 
level was 12.4% (12/97). Two samples had 
mixed infections involving S. agalactiae and 
S. aureus, and of the 19 isolates, these bacteria 
accounted for 57.9% (11 isolates) and 21.1% (4 
isolates), respectively. There were three CPS 
isolates other than S. aureus, and these 
contagious mastitis-causing bacteria 
(S. agalactiae and CPS) accounted for 94.7% 
(18/19). One Klebsiella isolate causing 
environmental mastitis was detected; however, 
E. coli was not detected. Sub-clinical mastitis 
was found at 12 farms; thereby, both clinical 
mastitis and sub-clinical mastitis were identified 
in cattle at one farm. 
Clinical and/or sub-clinical mastitic cattle were 
present on 33.0% (95% CI: 24.0-43.4, 32/97) of the 
farms, based on the questionnaire survey and 
Influence of Mastitis and Repeat Breeding Incidence on Participation in the Animal Insurance Program 
466 Vietnam Journal of Agricultural Sciences 
laboratory examination results. The proportion of 
farms with mastitic cattle was not significantly 
different between insured (34.2%, 13/38) and non-
insured farms (32.2%, 19/59, p = 1). There was 
also no significant difference in terms of the 
incidence rates of clinical and/or sub-clinical 
mastitis between insured (29.3%, 17/58) and non-
insured farms (22.1%, 21/95, x2 = 0.6527, p = 0.42). 
Table 1. Farm size and number of milk samples 
Insurance 
Farms in 
Yen Bai 
Farms in 
Van Hoa 
Mean herd size 
(range) 
Adult cows 
Milk samples 
(sampling fraction) 
l 16 22 5.4 (2-22) 153 58 (37.9%) 
Non-insured 33 26 5.9 (1-13) 239 95 (39.7%) 
Total 49 48 5.7 (1-22) 392 153 (39.0%) 
Figure 2. Statistical analysis results
Kentaro Koide et al. (2019) 
https://vjas.vnua.edu.vn/ 467 
The average scores regarding farmers’ 
awareness of mastitis were not significantly 
different between insured (3.22, 95% CI: 3.0-4.5) 
and non-insured farms (2.88, 95% CI: 2.75-4.00, p 
= 0.36). For the treatment of mastitis, 77% (64/83) 
of farmers called a veterinarian, whereas 23% 
(19/83) of farmers called other staff or treated the 
disease themselves. There was no significant 
difference between insured and non-insured farms 
in terms of factors relating to mastitis. 
Incidence and farmers’ awareness of repeat 
breeding 
Ninety-three farmers answered the questions 
relating to reproductive difficulties, and the 
results indicated that repeat breeding occurred at 
38.7% (36/93) of the studied farms. The 
proportion of farms with these reproduction-
related problems did not differ between insured 
(44.4%, 16/36) and non-insured farms (35.1%, 
20/57, x2 = 0.47, df = 1, p = 0.49). In addition, 
the average score of awareness of repeat breeding 
was not significantly different between insured 
(3.2, 95% CI: 2.5-4.5) and non-insured farms 
(2.8, 95% CI: 2.50-3.75, p = 0.35). Artificial 
insemination was used at all the farms. 
Discussion 
The main purpose of this study was to test 
the hypothesis that Vietnamese dairy farmers 
were motivated to participate in an animal 
insurance program due to experience with 
chronic production diseases, even though the 
program targeted acute infectious diseases. For 
that reason, two economically important 
diseases, mastitis and repeat breeding, were 
examined. 
There were no significant differences in 
terms of farm size, feed management, 
vaccination, or disease occurrence between 
insured and non-insured farms in this study. In 
laboratory analyses, contagious pathogens 
associated with mastitis were identified much 
more frequently than environmental pathogens, 
indicating that the milking method is more 
important than environmental factors in efforts to 
control the spread of mastitis in this region. In 
this study, the p-values of most factors were 
greater than 0.30, but the p-value associated with 
the milking method was relatively lower (p = 
0.16), and farms with milking machines tended 
not to participate in the insurance program. 
Milking by machine is a sign of intensive dairy 
farming, and economically developed farmers 
may evaluate the significance of the program 
carefully. Another study carried out during the 
same period but with different farmers (Kono et 
al., 2017) showed that a farmer’s decision to 
purchase animal insurance was affected by the 
absence of a trustworthy person nearby and a low 
rate of time discounting. Such sociological 
factors seemed to be more significant 
determinants of insurance participation by dairy 
farmers than disease burden. 
Conclusions 
This study found that the incidence of two 
important production diseases, mastitis and 
repeat breeding, was not the primary determining 
factor for the decision to participate in the animal 
insurance program in Ba Vi, Vietnam. The risk 
factors for mastitis and repeat breeding in 
Vietnam will be published elsewhere. 
Acknowledgements 
This study was supported by KAKENHI 
Grant Number 25304035, from the Ministry of 
Education, Culture, Sports, Science, and 
Technology of Japan. 
Conflicts of Interest 
The authors declare no conflicts of interest. 
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