Relationship between teat morphological traits and subclinical mastitis in Frieswal dairy cows

The present study was aimed to investigate the relationship between selected morphological traits of teat and subclinical mastitis (SCM) in Frieswal crossbred dairy cows. A total of 1040 quarters from 261 lactating cows were evaluated for teat shape (bottle/fleshy/collapsed/conical/normal/pencil and short), teat-end shape (dished/flat/funnel/pocketed/pointed and rounded), teat orientation (aligned/misaligned) and teat position (front and rear; left-sided and right-sided). Each udder quarter was screened with California Mastitis Test (CMT) for the purpose of defining quarter health status. Data were analysed using Chi-square test and multivariable logistic regression procedure. An overall prevalence of SCM (CMT positive) at quarter level was 30.6%. Most of the teats had normal or cylindrical shapes (48%), dished teat-ends (40.7%), and aligned (central or squared) in orientation (65%). At bivariable level, significant association of SCM with teat shape, teat position, teat orientation, parity, and stage of lactation was observed (P < 0.05 to P < 0.001). Teat-end shapes showed some association with SCM (P = 0.07). Results of multivariable analysis showed that pencil-shaped teats were least associated with SCM (P < 0.05) as compared to other teat shapes. Prevalence of SCM was also higher in rear teats (P = 0.015), misaligned teats (P = 0.01), and cows in second or higher parities (P < 0.01) and late stage of lactation (P < 0.001). The results of the present study indicate that selected morphological traits of teat are associated with SCM in Frieswal crossbred cows; therefore, selection towards desirable morphological traits could help reduce mastitis in this breed.     

Improving smallholder cattle reproductive efficiency in Cambodia to address expanding regional beef demand

This study aimed to identify factors associated with cattle reproductive output in rural smallholder farms in Cambodia in order to determine the main causes of reproductive failure and design efficient interventions for improvement. The majority of the nation’s beef is produced on smallholder farms where productivity is constrained by poor animal reproductivity reflected in the recent livestock population decline of approximately 13 % from 2009 to 2013. Farmers (n?=?240) from 16 villages from five provinces were surveyed in mid-2015 to determine their baseline knowledge, attitude and practices (KAP) associated with cattle reproduction. In addition, 16 case studies from three of these provinces were conducted to provide a more detailed assessment of current cattle reproductive husbandry practices. In order to assess the reproductive impact of previously implemented interventions, an endpoint KAP survey and longitudinal health and husbandry study from three Cambodian provinces conducted between 2008 and 2013 were also analysed. Three multivariable prediction models (two KAP and one longitudinal) identified the following significant factors associated with the reproductive outcomes ‘number of calves born’ or probability that cows ‘gave birth’: target feeding (P?=?0.074), growing vegetables (P?=?0.005), attitudes towards cattle vaccination (P?=?0.010), improving bull selection (P?=?0.032), local breed use (P?=?0.005), number of joining attempts (P?<?0.001), discontinuation of animal draught practices (P?=?0.003) and retention of breeding animals (P?<?0.001). The identification of significant factors and interventions in this study has led to intervention recommendations that can potentially improve reproductive efficiency, combat the declining cattle population and improve smallholder capacity to supply to expanding regional meat demand in South-East Asia and China.     

Prevalence of bovine subclinical mastitis and antibiotic susceptibility patterns of major mastitis pathogens isolated in Unguja island of Zanzibar,Tanzania

A cross-sectional study was conducted between January and July 2014 in Unguja island of Zanzibar to establish prevalence of subclinical mastitis (SCM) in smallholder dairy cows and patterns of antibacterial susceptibility of major mastitis pathogens isolated. A total of 416 dairy cows from 201 farmers were randomly selected from three districts of Unguja Island to participate in the study. Questionnaire interview, field observation, individual cow examination, California Mastitis Test (CMT) and bacteriological examination were carried out. Kirby-Bauer disc diffusion technique was used to test drug sensitivity for common bacteria isolated. Based on CMT results, the overall prevalence of SCM was 28.6, 48.8 and 64.7% at quarter, cow and farm level, respectively. Prevalence of bacterial infection was recorded at 42.9, 70.9 and 78.6% at quarter, cow and farm examined, respectively. The common bacteria isolated included Staphylococcus aureus (36.8%), Pseudomonas aeruginosa (17.8%), Staphylococcus epidermidis (16.1%), Klebsiella spp. (9.5%), Micrococcus spp. (6.3%) and Escherichia coli (4.9%). In conclusion, findings of this study demonstrated high level of subclinical mastitis at farms, cows and quarters levels with both contagious and environmental bacterial pathogen involved. Therefore, efforts should be directed to the decreased subclinical mastitis by improving sanitary measures and proper milking practice.     

<Emphasis Type="Italic">Staphylococcus aureus</Emphasis> intramammary infection affects milk yield and SCC of dairy cows

Staphylococcus aureus (S. aureus) is the most prevalent infectious microorganism affecting dairy cattle worldwide, and its pathogenic characteristics facilitate its spread in dairy herds. S. aureus intramammary infections (IMI) are mainly subclinical, and associated losses can exceed average herd losses where the pathogen is not isolated. However, the extent it affects milk composition at udder and quarter levels is still unknown, and cow composite milk losses may be underestimated due to the dilution effect. The aim of this study was to investigate the effects of S. aureus subclinical mastitis on mammary quarter milk yield and composition. In order to determine the effects of the pathogen on milk yield and composition at quarter level, a pairwise comparison of infected and non-infected mammary quarters (n?=?28) from two dairy herds was carried out. Quarters were individually milked, and milk production and composition were assessed. S. aureus has increased somatic cell counts at quarter level; however, no effect of S. aureus IMI on milk lactose, fat, and protein contents was observed. Fat yield from infected quarters decreased, but losses due to the infection caused by S. aureus were not associated with quarter positioning in cows.     

Comparative performance of dairy cows in low-input smallholder and high-input production systems in South Africa

The aim of this study was to benchmark the performance of dairy cows in the low-input smallholder system against their counterparts in the high-input system, in South Africa. Data comprised of cow performance records from the national dairy recording scheme. Performance measures included production (305-day yields of milk, fat, and protein), lactation length, somatic cell count (SCC), and reproductive traits, represented by age at first calving (AFC) and calving interval (CI). Least squares means of each trait were compared between the two systems, and lactation curves for production traits and SCC were plotted for each production system. Mean yields of milk, fat, and protein were significantly (P?<?0.05) lower in the smallholder (4097?±?165, 174?±?5.1, and 141?±?4.5 respectively) compared to the high-input system (6921?±?141, 298?±?4.7, and 245?±?4.1 respectively). Mean lactation length was significantly (P?<?0.05) shorter for the smallholder (308?±?15.1) than the high-input system (346?±?12.8). Log-transformed somatic cell count (SCS) was, however, significantly (P?<?0.05) higher in the smallholder (2.41?±?0.01) relative to the high-input system (2.27?±?0.01). Cows in high-input herds showed typical lactation curves, in contrast to the flat and low peaking curves obtained for the smallholder system. Cows on smallholder herds had their first calving significantly (P?<?0.05) older (30?±?0.5) than those in the high-input system (27?±?0.5). There was, however, no significant difference (P?<?0.05) in CI between the two systems. These results highlight large room for improvement of dairy cow performance in the smallholder system and could assist in decision-making aimed at improving the productivity of the South African dairy industry.     

Effect of mixed maize-legume silages on milk quality and quantity from lactating smallholder dairy cows

The study investigated the effect of the following maize:legume (70:30) mixed crop silages: maize:cowpea, maize:velvet bean, and maize:lablab on milk production during the 2016 dry season. Using a 5?×?5 double Latin square design, five Holstein-Friesian crossbred cows in early lactation (30?±?15 days) and five Jersey crossbred cows in early lactation (25?±?10 days) were given the supplementary mixed crop silage diets at 0.5 kg/l of milk produced over 105 days. Commercial dairy meal and sole maize silage were used as positive and negative controls, respectively. Milk yield was significantly higher (P?< 0.05) in cows given the dairy meal compared to mixed crop silages; however, milk yield was also significantly higher (P?< 0.05) for cows given the three mixed crop silages compared to cows given sole maize silage. Cows given mixed crop silages produced milk of significantly higher protein content (P?< 0.05) than those given sole maize silage. There was no significant difference (P?> 0.05) in butterfat content of milk across all the dietary treatments. The dietary cost of producing 1 l of milk was highest at 0.31USD/l for cows given commercial dairy meal and lowest for cows given maize:velvet bean and maize:cowpea silage at 0.19USD/kg. The highest dietary gross margins of 68% were observed when cows were given maize:velvet mixed silage compared to commercial dairy meal (47%) and sole maize silage (57%). The 70:30 maize:legume mixed crop silages showed the capability to increase milk quantity and quality at very low production costs in smallholder dairy schemes.     

Effect of feeding slowly fermentable grains on productive variables and amelioration of heat stress in lactating dairy cows in a sub-tropical summer

Feeding low-fiber and high-energy diets to dairy cows is one approach to ameliorate heat stress (HS) by reducing heat increment (HI) during digestion. However, rapidly and slowly fermentable cereal grains differ in their HI. The aim of this experiment was to quantify if feeding slowly fermentable grains ameliorated the physiological responses to HS and improved milk production (MP) in dairy cows. Holstein-Friesian lactating dairy cows were housed in shaded pens and were fed either a total mixed ration (TMR) plus wheat (TMRW), a TMR plus wheat treated with 2% of a commercial starch-binding agent (TMRB), or a TMR plus corn (TMRC) (n?=?8 cows per diet) during summer in Queensland, Australia. Respiration rate (RR) and panting score (PS) were measured four times a day; rumen temperature (RuT) was recorded every 20 min, and rectal temperature (RT) and milk samples were obtained every 4 days. Cows fed slowly fermentable grains had higher milk production (MP) than cows fed TMRW, and cows fed TMRC had lower RT than those fed TMRW and TMRB (P?<?0.001). Rumen temperature was positively correlated with temperature-humidity index and negatively correlated with MP (P?<?0.05). In summary, feeding TMRC ameliorated HS as indicated by lower RT and improved MP in dairy cows. Milk production was improved with starch-binding agents; however, this was not associated with efficient thermoregulatory responses. Furthermore, determination of RuT enabled the prediction of changes in physiological variables and productive responses due to HS in lactating dairy cows.     

Presence of <Emphasis Type="Italic">Ureaplasma diversum</Emphasis> in the genital tracts of female dairy cattle in Mato Grosso State,Brazil

Ureaplasma diversum infection in bovine females may result in various reproductive problems, including granular vulvovaginitis, abortion, weak calves, salpingitis, and spontaneous abortion. The presence of U. diversum in a dairy bovine population from midwestern Brazil has not been established. The aim of this study was to determine whether U. diversum was present in dairy cattle from midwestern Brazil using polymerase chain reaction (PCR). Vulvovaginal mucus was analyzed from 203 cows located in six municipalities in the north region of Mato Grosso State, Brazil. A total of 25% of dairy cows with vulvovaginitis were positive for U. diversum. The factors evaluated were included in a multivariable logistic regression model with the presence of at least one positive cow in the herd serving as the dependent variable. Three variables were significantly associated with a U. diversum-positive PCR and were included in the final multivariable model: number of parities, vulvar lesions, and reproductive problems. For each new parity, the chance of U. diversum infection decreased 0.03-fold, indicating that cows with the highest number of parities were more protected. The presence of vulvar lesions was increased 17.6-fold in females positive for U. diversum, suggesting that this bacterium could be related to the red granular lesions in the vulvar mucosa, whereas reproductive problems were increased 7.6-fold. However, further investigations should be conducted to ascertain the effects of U. diversum in association with other mycoplasma species in the herds studied.     

Use of serology and real time PCR to control an outbreak of bovine brucellosis at a dairy cattle farm in the Nile Delta region,Egypt

Background

Bovine brucellosis remains one of the most prevalent zoonotic infections affecting dairy cattle in developing countries where the applied control programs often fail. We analyzed the epidemiologic pattern of bovine brucellosis in a dairy cattle herd that showed several cases of abortions after regular vaccination with RB51 (B. abortus vaccine). In 2013 thirty dairy cows, from a Holstein-Friesian dairy herd with a population of 600 cattle, aborted five months post vaccination by a regular RB51 vaccine. Blood samples were drawn from milking cows and growing heifers, as well as heifers and cows pregnant up to 6 months. These samples were collected in June 2013 (n?=?257) and May 2014 (n?=?263) and were tested by real time (rt)-PCR as well as serological tests, in particular Rose Bengal Test (RBT), Enzyme-Linked Immunosorbent Assays (ELISA) and Fluorescence Polarization Assay. Tissue specimens were also collected from an aborted fetus and cultured. Isolates were subjected to bacteriological typing tests at the genus and species levels.

Results

Five months post vaccination with RB51 vaccine, Brucella (B.) DNA was detected in blood samples of cows by rt-PCR. The serological tests also revealed the spread of Brucella field strains within the herd in 2013. Four Brucella isolates were recovered from specimens collected from the aborted fetus. These isolates were typed as follows: one B. abortus RB51 vaccine strain and three isolates of B. abortus field strain. The seropositive cows with positive rt-PCR might indicate an infection by the Brucella field strain; while the positive rt-PCR results from seronegative animals may either be due to circulating RB51 vaccine DNA in vaccinated animals or to circulating field strain in infected animals before seroconversion.

Conclusion

The results herein suggest that PCR can be a good supplementary tool in an outbreak situation, if an assay is available that can differentiate vaccine and field strains with a high analytical sensitivity. We recommend using RBT and ELISA in parallel in outbreak situations, to identify as many infected animals as possible during the initial screenings. This test procedure should be repeated for at least three successive negative tests, with one month interval.

     

Comparison of milk fatty acid profiles measured on Kouri cows near Lake Chad and on dairy cattle as reported by meta-analytical data

Kouri (Bos taurus) is a breed aboriginal from Lake Chad and threatened with extinction. This study aimed to compare milk fatty acid profiles measured on Kouri cows and on high-yielding dairy cattle in Europe and elsewhere as reported by meta-analytical data (22 experimentations). Milk samples were collected from 14 Kouri dairy cows in dry season (March to June) and fatty acids (FA) were determined by gas chromatography. Overall, 32 FA have been identified. Kouri showed lower values (P < 0.001) in the sum of saturated FA (SFA, ?10.9 pts), cis-9, cis-12 18:2 (?1.00 pt) (P < 0.01, higher values (P < 0.001) in the sum of monounsaturated FA (MUFA, +15.3 pts), C18:0) (+3.5 pts), cis-9, trans-11 C18:2-CLA (+1.00 pts), trans-11 18:1 (+1.4 pts) and (P < 0.01) in cis-9, C18:1 (+3.00 pts) acids. The differences between the milk FA profile of the Kouri cows and that obtained from meta-analytical data could be the possible consequence of the use of particular lake pastures by Kouri cows.     

Screening food-borne and zoonotic pathogens associated with livestock practices in the Sumapaz region,Cundinamarca, Colombia

Hazardous practices regarding antibiotics misuse, unsanitary milking procedures, and the commercial sales of raw milk and unpasteurized dairy products are currently being practiced by livestock farmers in the Sumapaz region (Colombia). The purpose of this study was to screen for food-borne and zoonotic pathogens associated with local livestock practices. We evaluated 1098 cows from 46 livestock farms in the Sumapaz region that were selected by random. Of the total population of cattle, 962 animals (88%) were tested for bovine TB using a caudal-fold tuberculin test and 546 (50%) for brucellosis by a competitive ELISA. In the population tested, 23 cows were positive for Brucella sp. representing a 4.2% seroprevalence and no cases of bovine tuberculosis were found. In addition, food-borne contamination with Escherichia coli and Staphylococcus aureus was assessed together with antibiotic susceptibility for ten different antibiotics in milk samples from 16 livestock farms. We found that 12 of the farms (75%) were contaminated with these food-borne pathogens. Noteworthy, all of the isolated pathogenic strains were resistant to multiple antibiotics, primarily to oxytetracycline and erythromycin. Our findings suggest that livestock products could be a source of exposure to Brucella and multidrug-resistant E. coli and S. aureus strains as a result of unhygienic livestock practices in the Sumapaz region. Training in good farming practices is the key to improving safety in food production.     

Colostrum quality,IgG absorption and daily weight gain of calves in small-scale dairy production systems in Southern Vietnam

Dairy production is expanding rapidly in Vietnam, but still, the smallholder farms are most common. The aim of this study was therefore to get improved knowledge about colostrum quality in dairy cows, immunoglobulin G (IgG) absorption, daily weight gain in dairy calves and calf management in small-scale dairy production systems in Southern Vietnam. A field survey was conducted on 40 farms, with two calves on each farm being intensively studied. It was observed that newborn calves were separated from their dams immediately after birth and offered 2–4 L first colostrum within 4 h by bucket feeding. The first colostrum IgG level, fat and protein content were on average 35.6, 4.8 and 21.4%, respectively, and 91% of the cows produced colostrum of good quality (Brix value >22%). The IgG level in serum of calves, measured as Brix value, was on average 9.3%. Colostrum in the samples studied was of quite high quality and on-farm observations showed that colostrum was offered on the first day of calf life, so passive transfer of immunity to the calves was high. In total, 10% of the calves had a Brix value for IgG in serum lower than 8.3%, indicating that those calves had suffered from failure of passive immune transfer (FPT). The daily weight gain of female and male calves was 0.75 and 0.54 kg, respectively. Serum IgG was positively correlated with colostrum protein (P = 0.002). Daily weight gain and diarrhoea was negatively correlated (P = 0.001).     

Milk production and fatty acid profile of dairy cows grazing four grass species pastures during the rainy season in small-scale dairy systems in the highlands of Mexico

The study evaluated small-scale dairy systems with continuous grazing of pastures based on three temperate grasses festulolium (FL), tall fescue (TF), and perennial ryegrass (RG), compared with subtropical kikuyu grass (KG). All pastures were associated with white clover (Trifolium repens L.). Twelve multiparous Holstein cows were assigned to a 4?×?4 Latin square replicated three times with 14-day experimental periods. Sampling and analyses of pastures, concentrates, and animal variables followed standard procedures. FL showed a significantly (p?<?0.05) higher mean sward height, but there were no differences (p?>?0.05) in net herbage accumulation. There were significant differences (p?<?0.05) among pastures for CP, NDF, ADF, in vitro digestibility of OM (IVOMD), and estimated metabolizable energy (eME). There were no differences (p?>?0.05) between treatments for milk yield and composition, live weight, or body condition score. There were significant differences (p?<?0.05) in fatty acid values for pastures in C14:0, C16:1, and C18:3n3. There were significant differences between treatments (p?<?0.05) in milk contents for C18:0, C18:1t11, and C18:2c9t11. Grazing FL, TF, RG, or KY pastures showed no differences in milk yields. Higher values for C18:0, C18:1t11, and C18:2c9t11 were detected in KY, RG, and TF. RG had significantly higher MUFA than FL and higher PUFA than TF. A value under 65% of SFA, a ratio of n-6/n-3 lower than 4, and an atherogenic index of 1.7 are indicators of milk with beneficial effects for human health.     

Seroprevalence of <Emphasis Type="Italic">Anaplasma marginale</Emphasis> and <Emphasis Type="Italic">Babesia bigemina</Emphasis> infections and associated risk factors in Machakos County,Kenya

Anaplasma marginale and Babesia bigemina are important tick-borne pathogens of cattle. A cross-sectional survey was undertaken to determine the seroprevalence of A. marginale and B. bigemina infections and identify associated risk factors on traditional smallholder farms in Machakos County, Kenya. A total of 421 cattle from 127 farms from four divisions in the county were sampled and visited between September and November 2007. The farms were selected by a proportional allocation approach based on the number of farms in the four divisions previously selected by stratified random sampling method. Information on animal and individual farm management variables was obtained using standardized questionnaires. Prevalence of serum antibodies due to A. marginale and B. bigemina pathogens was determined using the enzyme-linked immunosorbent assay (ELISA) technique. The relationship between the seropositivity and associated risk factors was assessed by multivariable analyses using standard logistic regression models. The overall estimation (and their 95% confidence intervals) of A. marginale and B. bigemina seropositivity at the animal level was 53.4% (48.5%, 58.2%) and 40.6% (35.8%, 45.4%), respectively. Two variables, “animal age” and “administrative division,” were significantly associated with the A. marginale seroresponse. Three variables, “animal age” “grazing system” and “administrative division” were significantly associated with the B. bigemina seroresponse. These findings suggest possible indicators of existence of endemic instability for the two infections. The study identifies characterization of environmental suitability for the vectors and how they interact with grazing systems to cause the infections as an area for further studies, for improved understanding of the infections and in designing disease control programs.     

Effect of dietary inclusion of date seed (<Emphasis Type="Italic">Phoenix dactylifera</Emphasis> L.) on intake,digestibility, milk production,and milk fatty acid profile of Holstein dairy cows

The objective of this experiment was to investigate the influence of ground date seed (GDS) on intake, digestibility, and milk yield and milk fatty acid (FA) composition of lactating Holstein cows. The experimental design was a 4?×?4 replicated Latin square with eight lactating dairy cows with an average milk production of 35.5?±?1.5 kg and 75?±?5 days in milk (DIM). Dairy cows were fed one of the four treatments contained 0, 2, 4, and 6% of diet dry matter (DM) GDS in replacement of wheat bran. All diets contained the same amount of forages (alfalfa hay and corn silage). Dietary treatments had no effect on DM intake (DMI), total tract apparent digestibility, milk yield, and milk composition. Increasing GDS linearly decreased concentration of C13:0 and increased cis-9 C14:1 and trans-11 C18:1 (vaccenic acid) (P?<?0.05). A linear tendency for more C16:1 content in milk fat was observed with increasing GDS (P?=?0.06). Feeding GDS resulted in a linear decrease (P?<?0.01) in saturated FA (SFA) but increased milk fat monounsaturated FA (MUFA) and trans FA (TFA) (P?<?0.05). Therefore, low levels of GDS (up to 6%) in the diet of Holstein dairy cows can beneficially modify milk FA composition without any adverse effects on intake, digestibility, and milk yield.     

Effect of grape seed and skin supplement on milk yield and composition of dairy ewes

In the present study, we investigated the effect of grape seed and skin supplement (GSSS), on lactating dairy ewes’ production. Ten dairy pregnant ewes from northern Tunisia were allocated to two groups: control diet (C) and supplemented with 20 % (w/w) GSSS. The experiment lasted for 8 weeks and took place after 2 months of lambing. During the experiment, daily milk yield and milk composition were determined. Supplementation of the diet with GSSS increased milk production (P?<?0.001), calcium (P?<?0.01), free iron (P?<?0.01) and urea content (P?<?0.001) but had no effect on milk fat nor protein. From these data, it is concluded that the inclusion of GSSS in sheep diets increased significantly ewes’ milk yield.     

Antimicrobial resistance and virulence profile of enterococci isolated from poultry and cattle sources in Nigeria

This study investigated the occurrence, antimicrobial resistance and virulence of Enterococcus from poultry and cattle farms. Three hundred and ninety samples: cloacal/rectal swabs (n?=?260) and manure (n?=?130] were processed for recovery of Enterococcus species. Standard bacteriological methods were used to isolate, identify and characterize Enterococcus species for antimicrobial susceptibility and expression of virulence traits. Detection of antibiotic resistance and virulence genes was carried out by polymerase chain reaction. Enterococcus was recovered from 167 (42.8%) of the 390 samples tested with a predominance of Enterococcus faecium (27.7%). Other species detected were Enterococcus gallinarum, Enterococcus faecalis, Enterococcus hirae, Enterococcus raffinosus, Enterococcus avium, Enterococcus casseliflavus, Enterococcus mundtii and Enterococcus durans. All the isolates tested were susceptible to vancomycin, but resistance to tetracycline, erythromycin, ampicillin and gentamicin was also observed among 61.0, 61.0, 45.1 and 32.7% of the isolates, respectively. Sixty (53.1%) of the isolates were multidrug resistant presenting as 24 different resistance patterns with resistance to gentamicin-erythromycin-streptomycin-tetracycline (CN-ERY-STR-TET) being the most common (n?=?11) pattern. In addition to expression of virulence traits (haemolysin, gelatinase, biofilm production), antibiotic resistance (tetK, tetL, tetM, tetO and ermB) and virulence (asa1, gelE, cylA) genes were detected among the isolates. Also, in vitro transfer of resistance determinants was observed among 75% of the isolates tested. Our data revealed poultry, cattle and manure in this area are hosts to varying Enterococcus species harbouring virulence and resistance determinants that can be transferred to other organisms and also are important for causing nosocomial infection.     

Prevalence and risk factors of subclinical mastitis in lactating dairy cows in north and south regions of Bangladesh

The purpose of the study was to identify the potential risk factors for subclinical mastitis (SCM) in lactating dairy cows in Bangladesh. A cross-sectional study was carried out on randomly selected 212 smallholder dairy farms of Sadar upazilas of Rangpur, Mymensingh, and Satkhira districts of Bangladesh during January to October 2011. The direct interview using a structured questionnaire and physical examination of the cows were done to collect data on 15 variables. Milk samples collected from study cows were subjected to California Mastitis Test (CMT). The diagnosis of SCM was based on the results of CMT and physical examination of udder and milk. The bivariable followed by multivariable analysis was done using SPSS 17.0. Of the total cows examined, 20.2 % had subclinical mastitis. In bivariable analysis, eight risk factors were identified. However, in the final model of multivariable analysis, four potential risk factors were identified. These were history of previous clinical mastitis (odds ratio (OR) 10.51, p?<?0.001), pendulous type of udder (OR 2.26, p?=?0.008), no grass feeding (OR 1.84, p?=?0.039), and body condition score (BCS) 2.5 or less (OR 7.25, p?=?0.054). Four different factors were significantly associated with the occurrence of subclinical mastitis, which need to be considered in the control of the disease. However, particular emphasis should be given on grass feeding and BCS because these traits can be modified or improved to allow prevention of SCM.