Farm Management and Economic Factors Associated with Bulk Tank Total Bacterial Count in Holstein Dairy Herds in Iran

doi:10.21203/rs.3.rs-1504507/v1

The objectives of this research were (1) to study different factors affecting milk total bacterial count (TBC) and (2) to estimate economic values associated with TBC in Holstein dairy herds in Iran. The relationships between bulk tank TBC and farm management and economic factors were examined on 56 randomly selected intensive dairy farms. Herd management factors associated with bulk tank TBC were determined using mixed linear models. The average natural logarithm of bulk tank TBC was the dependent variable. Also, a quadratic equation was developed for economic analyses (penalties and bonuses) associated with TBC. The median bulk tank TBC for the sample herds was 298,930 cfu/mL ranging from 80,880 to 1,185,350 cfu/mL. The average economic premium opportunity from bulk tank TBC was US$ 1.32 per ton of milk ranging from US$ 0.02 per ton of milk for herds applying wet tissue as teat cleaning material and washing the water troughs three times per day to US$ 5.20 per ton of milk for herds with dirty barns. Results showed that the following management factors were associated with low TBC and high economic bonus: herd size, bedding material, presence of vet, milk delivery to the processor multiple times per day, water quality control, frequency of cleaning water troughs, barn hygiene, udder washing material, teat cleaning material, having a hospital pen, frequency of calving area disinfection, education level of workers and material of milking parlor wall. In conclusion, our findings highlight the need to pay more attention to farm management and economic factors to reduce milk TBC in Iran.

milk quality

dairy cattle

TBC control program

management practices

Milk has various essential nutrients such as minerals, vitamins, and easily digestible proteins with balanced AA profiles that are significant in sustaining most body functions (Zucali et al.,2011). Milk also provides an excellent growth environment for microorganisms, and their propagation in milk leads to spoilage, decreased nutritional value, altered sensory and physicochemical properties of milk, and increased risk of foodborne diseases (Claeys et al., 2013; Boor et al., 2017; Porcellato et al., 2018). Hygienic profile, characterized by contamination levels and distributions of microorganisms, is a critical parameter of raw milk quality (Zucali et al., 2011). Total bacterial count (TBC) has commonly been adopted as an index of microbial quality for milk over 100 year because of its direct correlation to spoilage (Boor et al., 2017). TBC is the bacteria growth per ml of milk over a fixed period (Blowey and Edmondson, 1995). High TBC milk should be avoided since some bacteria (Staphylococcus aureus, Escherichia coli, and Streptococcus agalactiae) found in raw milk can cause diarrheal disease and food poisoning (Gilmour and Rowe, 1990). An increase in TBC can be related to mastitis organisms, environmental contaminants, dirty milking equipment, or refrigeration failure (Blowey and Edmondson 1995). Jayarao et al. (2004) documented that herd size and farm management practices influence bacterial counts in bulk tank milk. Furthermore, Magnusson et al. (2007) reported that the type of bedding material causes spore transmission to the udder and then to raw milk. Kelly et al. (2009) documented that use of heated water in the milking parlor, participation in a milk recording scheme was associated with low TBC. According to regulations in Iran, the maximum TBC is 300,000 cfu/ml, and it is much lower in other countries. European Union laws dictate the bacterial count of milk must not go beyond the average value of 100,000 cfu/ml over two months with at least two tests per month. Quality premiums have had a strong influence on milk quality through reduced TBC. For some countries, including Iran, the effects of high TBC on milk quality and other dairy products might not entirely be realized by farmers. Farmers are often not aware of the positive economic impacts of the TBC decrease. Dairy farmers can reduce TBC by improving management and hygiene practices and achieving more economic benefits. To make significant strategic decisions pertaining to TBC control in raw milk, it is essential to adopt different management practices to estimate the possible effects of TBC on milk production. In most studies, the impact of different factors on the production and composition of milk under different management conditions has been mentioned; however, so far, the economic aspects regarding the TBC of milk in Holstein herds in Iran and other countries have not been investigated. This study's principle objective is to develop a bio-economic model to economically analyze the TBC and predict the benefits and the new marketing opportunities provided for farmers due to TBC reduction in milk. The results of this study can be used to improve best management practices regarding milk production, and producers can achieve more economic gain.

Sampling Procedure and Experimental Design

In this study, data were obtained in cooperation with one of the major milk processors of Iran's dairy industry, Kalleh Dairy Company (Amol, Iran). Data were obtained on the annual milk supply for all farmers supplying to the milk processor in Iran. The milk processor provided data on milk volume and bulk tank TBC on a collection basis from January 2016 to December 2017, including a total of 23,694 observations. Milk was collected from the farms at a frequency range of one to four days. The TBC of milk supplied by the farms was regularly scanned in Solico Kalleh Central Laboratory with a BactoScan machine at almost every milk collection. BactoScan (Foss Electric) is a flow cytometry technology that can count the bacteria individually in ten minutes (Murphy et al., 2016). A total of 100 herds were randomly chosen, with the percentage selected from each stratum being weighted by the frequency of herds within strata relative to the sample population. These farms were invited to participate in a questionnaire survey; 56 of them decided to participate. These farms were all the company's milk suppliers from different cities in Iran. The farms were visited in each face-to-face interview with the farmers, and the questionnaire was completed. The questionnaires which were mainly developed on the basis of milk quality and major factors affecting TBC of herds, including questions about farms condition, hygiene, development level of the farms and factors affecting milk quality. After completing the questionnaires, the information was input into Microsoft Excel (2013). Due to the nature of the count and the large dispersion of bacterial count data, a logarithmic transformation was used to normalize the data.

Statistical Analyses

Statistical procedures were conducted using SAS/STAT 9 (SAS Institute Inc. 2002). The distribution of management practices across herds was determined using the frequency procedure (PROC FREQ). The following mixed linear model (PROC MIXED) with class statements for management factor, province, year, and the season and herd as a random effect were used to study the effect of TBC on milk yield under various management factors:

y_ijklm = µ + Prov_j + Year_k + Season_l + MF_m + (Year × Season)_kl + (Year × MF)_km + (Season × MF)_lm + (Year × Season × MF)_klm + Herd_i + e_ijklm (1)

where y_ijklm= logarithm of TBC ijklm ; µ = the overall mean; Prov_j= the fixed effect of province j; Year_k= the fixed effect of year k; Season_l = the fixed effect of season l; MF_m= the fixed effect management factor m; (Year × Season)_kl = the interaction between year k and season l; (Year × MF)_km = the interaction between year k and management factor m; (Season × MF)_lm =interaction between season l and management factor m; (Year × Season × MF)_klm= the interaction between year k, season l, and management factor m; Herd_i = the random effect of herd i; e_ijkl = the random residual effect with mean 0 and homogenous variance $\sigma$². In all statistical analyses, least square means were calculated and significance was declared at P < 0.05 and trends at P ≥ 0.10. The Shapiro-Wilk test declared that logarithm of bulk tank TBC and residuals are normally distributed.

Economic Calculations

Currently, the milk pricing system in Iran is based on a price per kilogram of base milk and parentage of differential premium based on milk's fat and protein content. According to the premium/penalty system for TBC of milk determined by Iran Dairy Industry (IDI) to encourage farmers to improve milk quality, the TBC was categorized as follows: (1) < 300,000 cfu/mL, (2) from 300,000 to 500,000 cfu/mL, (3) from 500,000 to 1,000,000 cfu/mL, (4) from 1,000,000 to 2,000,000 cfu/mL, and (5) > 2,000,000 cfu/mL which are set a percentage differential premium from base milk price as + 2%, 0%, -1%, -2%, and − 5% respectively. In this system, premiums and penalties for TBC level per metric ton of milk are calculated as milk base price multiplied by a percentage of the differential premium. When TBC of milk was less than 300,000 cfu/mL, a bonus of US$ 6.20 was paid, which is equal to 2 percentage of the base milk price in 2017 in Iran in terms of US$.

Premium = 1000 kg × 0.31 (raw milk price) × 2% = US$ 6.20 per ton

Also, a penalty of US$ 15.50 per ton was set when the TBC of milk exceeded 2 million cfu/mL.

Penalty = 1000 kg × 0.31 (raw milk price) × (-5%) = US$ -15.50 per ton

It should be noted that the currency used in Iran is Rial (IRR). Economic calculations are expressed in US dollars, assuming an exchange rate of 1 US$ = 42,000 IRR.

To do the economic analysis, bulk tank TBC of the milk, which was 50,000 to 3 million cfu/mL, was categorized into groups with a range of 50,000. Logarithmic transformation was used to normalize TBC. Finally, the US$ 6.20 per ton of milk premium was determined for a TBC of 50,000 to 300,000, the best level of raw milk. A penalty of US$ -15.50 was also considered for a TBC of more than 2 million per ton of milk. To achieve the best method for economic analysis of bulk tank TBC, the second-order regression equation with R² = 0.8928 was fitted as follows:

Y = -39.488 X² + 152.88 X -121.64

where Y represents the premium and penalty of TBC, and X is the least square means corrected for each management factor as described in the statistical analysis section. This equation has been chosen due to the simplicity and magnitude of its coefficient of determination; premium and penalty for TBC were calculated for each management factor based on this equation.

Based on the frequency of TBC classes of milk tanks and the amount of premium and penalties considered for each qualitative milk class in terms of health, Economic Premium Opportunity (EPO) was calculated for each herd individually. Calculation of the EPO from TBC per kilogram of milk was as follows:

EPO (US$/ton of milk) = [Maximum TBC premium payment (US$ 6.20) – EPE (US$ / ton of milk)]

where EPE is the economic premium earned calculated as percentage differential premium multiplied by US$ 1000 × 0.31 kg of milk (raw milk price).

For example, if the differential premium from the base milk price for a production system with TBC < 1,000,000 was (-1%), then (1000 × 0.31× (-1%) = US$ -3.10 per ton of milk will be imposed as the penalty for a high level of TBC. The EPO, therefore, gives an estimation of the economic benefit that farmers may earn in their farms by changing the current management practices (6.20- (-3.10)) = US$ 9.30, here in this example.

The variation associated with on-farm factors was studied using data collected from the questionnaire. Across the 56 study herds, the mean and median TBC were 325,530 and 298,930 cfu/ml (range 80,880 to 1,185,350 cfu/ml), respectively (Table 1). The province effect was associated with TBC (P < 0.05) based on the results. Furthermore, effects of year, season, and interactions between them and each of them with management factors were significant on TBC (P < 0.01). The 3-way interactions among year, season and management factors were also significant (P < 0.01). As can be seen in Table 2, farms with size 500 ≤ adult cows had lower TBC than farms with size 500 ≥ adult cows (P < 0.01). Therefore, smaller herds received a lower economic premium due to higher TBC. 13 (23%) herds with sand bedding had lesser TBC and received greater economic premium than herds with bedding of dried manure, straw, or combined (P < 0.01). The results indicated the farms that used an on-farm vet had lower TBC and higher economic premiums than those used as visiting regularly. The farms (with size 500≤) that delivered milk multiple times per day had lesser TBC than those delivered some days in a week (P < 0.05). So these farms can receive high economic premiums. Farms performing water quality control (microbial and chemical) for less than a year had less TBC. They received great economic premiums (compared to more than a year and never done) (P < 0.05). For the factor of frequency of cleaning water troughs, three times a day caused low TBC and high economic premium (P < 0.05). Based on our questionnaire, the farms that cleaned barns had the lowest TBC compared with those that were relatively dirty or dirty (with higher coliforms) (P < 0.01). The results of our study showed there was no significant difference for switch trimming factor in the reduction of milk TBC. Most farms (75%) used warm water to wash udder and had higher TBC than herds using wet tissues, so they took lower economic premiums due to higher TBC (Table 2). Among teat cleaning materials, wet tissue had the highest effect on the reduction of milk TBC. Therefore, using this method, most farms could make more economic premium opportunities (P < 0.01). Also, some factors such as the education level of workers and material of milking parlor wall (as tile) had high significance on the number of milk TBC (P < 0.01). Finally, two factors, having a hospital pen and disinfection of calving area (as once a day), had a significant effect on TBC and economic premiums (P < 0.05) (Table 2).

Table 1

Descriptive statistics for the total bacterial count (× 1000 cfu/mL), herd size on 56 Iran dairy farms.
Variable	N^*	Mean	Median	Standard deviation	Minimum	Maximum
TBC^#	23694	291.02	200.00	572.39	0.00	38802.00
Herd TBC	56	325.53	298.93	185.03	80.88	1185.35
Herd size	56	619.66	169.00	1056.04	35.00	4691.00
^*N, number of observations; ^#TBC, Total Bacterial Count.

Table 2

Least square means of factors associated with total bacterial count and estimated economic premium opportunity on 56 Iran dairy farms
Management variables	Herd (%)	LTBC (TBC)^*	EPO^#	SE^†	p-value
Herd size (adult cows)					0.0008
< 200	30	2.36 (231)^a	1.70	0.04
200 to 500	34	2.22 (165)^a	0.70	0.08
500 to 1000	7	2.11 (128)^b	0.20	0.08
> 1000	11	2.13 (136)^b	0.30	0.06
Bedding material					0.0009
Sand	23	2.10 (125)^c	0.20	0.06
Dried manure	30	2.25 (180)^b	0.90	0.06
Straw	6	2.56 (364)^a	3.60	0.12
Combined^θ	41	2.32 (209)^ab	1.30	0.05
Presence of vet					0.0703
On-farm	76	2.31 (203)^a	1.20	0.04
Visiting regularly	24	2.19 (156)^b	0.50	0.06
Milk delivery to the processor					0.02
Once a day	9	2.22 (166)^ab	0.70	0.11
Multiple times per day	7	2.05 (112)^b	0.10	0.11
Multiple times per week	84	2.36 (232)^a	1.60	0.03
Water quality control					0.05
Less than a year	48	2.24 (172)^b	0.80	0.04
More than a year	34	2.38 (240)^a	1.80	0.05
Never done	18	2.33 (212)^a	1.40	0.07
Frequency of cleaning water troughs					0.02
After each milking time	13	2.32 (208)^a	1.30	0.08
Once a week	37	2.38 (242)^a	1.80	0.05
Whenever needed	34	2.28 (192)^a	1.10	0.05
Three times a day	16	2.04 (110)^b	0.02	0.10
Barn hygiene					0.001
Clean	84	2.28 (192)^b	1.10	0.03
Relatively dirty	14	2.52 (327)^a	3.10	0.08
Dirty	2	2.69 (487)^a	5.20	0.19
Switch trimming					0.37
Less than a year	61	2.29 (193)^a	1.10	0.04
More than a year	33	2.35 (224)^a	1.60	0.07
Never done	6	2.45 (280)^a	2.40	0.11
Udder washing material^‡					0.001
Warm water	75	2.37 (234)^a	1.70	0.04
Wet tissue	25	2.15 (140)^b	0.30	0.06
Teat cleaning material^‡,¶					0.0007
Tissue paper	37	2.34 (219)^a	1.50	0.05
Straw paper	18	2.30 (199)^a	1.20	0.07
Washable towel	14	2.34 (219)^a	1.50	0.07
No cleaning	20	2.34 (219)^a	1.50	0.06
Wet tissue	11	2.05 (111)^b	0.02	0.08
Having a hospital pen					0.03
Yes	59	2.25 (178)^a	0.90	0.04
NO	41	2.38 (239)^b	1.80	0.05
Frequency of calving area disinfection					0.03
Once a day	34	2.18 (152)^b	0.50	0.05
Twice a week	15	2.41 (259)^a	2.10	0.07
Once a week	34	2.33 (216)^a	1.40	0.05
Once a month	11	2.41 (260)^a	2.10	0.08
Never	6	2.37 (237)^a	1.70	0.13
Education level of workers					0.007
Illiterate	47	2.40 (249)^a	1.90	0.05
Elementary education	27	2.27 (184)^ab	0.90	0.06
Secondary education	13	2.13 (136)^b	0.30	0.08
Diploma and higher	7	2.28 (190)^a	1.00	0.10
Different levels of education	6	2.30 (199)^a	1.20	0.14
Material of milking parlor wall					0.005
Cement	49	2.33 (215)^a	1.40	0.04
Tile	44	2.17 (148)^b	0.40	0.04
Two types of materials	7	2.44 (276)^a	2.30	0.11
^*LTBC, log10 (TBC) (TBC = total bacterial count, TBC (×10³/ml)); ^# Economic premium opportunity from total bacterial count US$ per ton of milk; ^†SE, standard error; ^θDried manure combined with sawdust or sand or straw;^‡Conducted before cluster attachment;^¶All materials were disposable (except washable towel), single-use, and dry before use; ^a,b,c,d Means in a column with the same letter are not significantly different (P < 0.05).

The objective of this study was to determine the association between improved herd management practices and the quality of milk in terms of TBC. In the dairy industry, milk production and milk quality are of paramount importance. Therefore, it is necessary to observe the herd management factors associated with milk quality. Because of the framework of the study, it should be noted that the relationships reported do not indicate cause and effect relationships and should not be interpreted as such. In larger herds, the total bacterial count was low. In large farms, consultants and veterinarians are usually employed to advise management practices and system design. Therefore, increased farmer knowledge about the production system was likely associated with lower TBC found in larger herds. This is consistent with the findings of Van Shik et al. (2002), who found that milk samples from larger herds had a lower bacterial count in comparison to milk obtained from smaller herds. Miller et al. (2015) also found that lower mesophilic spores accompanied a larger herd size. Depending on the existing nutrients in bedding materials, a various range of microorganisms can be observed; consequently, the total bacterial counts of the herds on different types of bedding materials also vary (Rendos et al. 1975; Zdanowicz et al. 2004). Bacterial counts in inorganic bedding are typically lower than the organic ones, depending on the bacterial strain and the type of material (Fairchild et al., 1982). Our results show that herds that bedded cows on the sand had the lowest TBC. As reported by Zdanowicz et al. (2004), when cows were bedded on sawdust, the number of coliforms and Klebsiella spp. on the teats was greater than the number of Streptococcus spp. when the cows were on the sand bed. According to the results, farms employed on-farm vets showed a lower herd TBC. In addition to timely diagnosis and treatment of veterinary diseases, the presence of an on-farm vet can lead to the necessary health principles and positively influence TBC reduction in herds.

Farms that delivered milk to the company multiple times per day had the lowest TBC. Storing raw milk under refrigeration for a long time at the dairy farm and its delivery to the industrial factories can create a suitable environment for the growth of microorganisms and increase the TBC of milk (Silva et al., 2015). One of the Brazilian state requirements for producing raw milk with high quality is the duration of milk storage in refrigeration for 48 hours. For more remarkable performance, it is recommended to have a maximum storage time of up to 24 hours (Silva et al., 2015). Nonetheless, O'Connell et al. (2017) study indicated that milk could be stored for up to 96 hours at temperatures between 2 and 6 C with a negligible effect on its composition or properties. Water itself can be a source of contaminated bacteria, so water used in any part of the milking procedure must be of good quality (O’Brien, 2008, p. 73). Our results proved that water quality control was associated with a decrease in the bacterial count of the herd. Water hardness is referred to as calcium carbonate (CaCO3), which is hard water that increases the level of magnesium and calcium, having a negative effect on disinfection; furthermore, it causes both mineral sediments on surfaces and biofilm formation (Gleeson et al. 2013). Providing hygienic water is essential for producing quality milk. Water used in washing equipment must be as clean and healthy as drinking water (Bekuma and Galmessa, 2018). Bacterial contaminants in cow water troughs may be generated from various sources. Cows may contaminate the water troughs with cud or fecal material and peripheral materials such as dust, feed, or bedding (LeJeune et al. 2001). Based on our results, increasing the frequency of water troughs cleaning had a significant association with lower TBC. Cleaning facilities should be provided to prevent algae growth. Clean barns were significantly associated with lower TBC. A hygienic and dry environment for cows has a crucial role in preventing environmental mastitis (Bartlett et al. 1992). It is of paramount significance to take care of the barn hygiene to produce high-quality milk (Bekuma and Glamessa 2018). Long-tail hair can transmit contamination from the cow's body to the teat. Therefore, cows' tails should always be clipped switch trimming should always be done. However, as Kelly et al. (2009) reported, switch trimming effectively reduced TBC if done more than once a year. The present study did not show any significant relationship between switch trimming and TBC decrease.

Pre-milking udder washing procedure affected TBC. The use of wet tissue was highly associated with lower TBC of herds compared to warm water. As Elmoslemany et al. (2009) discussed, using water for Pre-milking udder preparation caused an increase in the total aerobic bacteria count. Water fluxing along the udder can transmit bacteria to the teat; as a result, increasing the risk of mastitis (Koster et al. 2006). Using wet tissue for teat cleaning had the lowest TBC among different materials in use. According to Murphy et al. (2005), teat preparation is one of the critical factors pertaining to TBC reduction. Various methods of teat cleansing have been evaluated to determine their effect on the presence of spores in milk. The most effective way (showing a 96% reduction) was using wet washable towels followed by drying with a paper towel (Magnuson et al. 2006). Rowe et al. (2019) suggested that cloth udder towels may act as a fomite for non-aureus Staphylococcus spp. (NAS) and Streptococcus spp. or Streptococcus-like organisms (SSLO). They recommended that laundered towels be completely dried in a hot air dryer. Our results show that using tissue paper and washable towels is not recommended for teat cleaning. The priority, in this case, is with wet tissue; the best choice was to use straw paper afterward. Our results revealed that lower TBC was in herds having hospital pens. The existence of a hospital in the farm is remarkably essential for treating animals. Increasing the frequency of calving area disinfection had an impact on TBC reduction. However, as Kelly et al. (2009) reported, the number of calving area disinfection was not significant in decreasing bacterial count. Paying attention to hygiene, in general, can reduce the risk of environmental pathogens exposure at the cubicles and calving parlor, and thus prevent the transmission of these contagious pathogens to milk during milking (Barkema et al., 1998). Different educational levels of workers were associated with a lower TBC of herds. The farms with illiterate workers had the highest TBC than farms employing workers with varying literacy levels. However, we could not find a pattern between increasing education and TBC reduction among other farms with literate workers of different educational levels. Our results suggested that the type of milking parlor material was associated with lower TBC. This issue requires the farmers to be aware of proper materials to cover the milking parlor wall. In this study, a total of 14 herd management practices including 48 levels of health, workers’ level of education, and housing conditions were examined, of which only three management factors (straw bedding, relatively dirty barns, and dirty barns) had the highest economic premium opportunity from TBC (Table 2). The production systems with dirty barns had the most increased economic premium opportunities (EPO) (5.20). At the same time, the lowest EPO (US$) belonged to the systems in which the water troughs were washed three times a day and wet tissue was used for teat cleaning (0.02) per kg of milk. It is an old standard in Iran to classify raw milk in terms of the TBC. The threshold of 300,000 cfu/ml of milk is a very high number to estimate TBC. It has led to many limitations for the country's dairy industry as the international legal constraints for TBC range usually are lower. As determined by European law (EEC, 1992, Council Directive 92/46/EEC), in the case of at least two tests per month, the maximum total bacterial count is not legally permitted to surpass a geometric average of 100,000 per ml over two months. A total of twenty-eight of the study farms had EPO < $ 2.2 per metric ton of milk, and twenty-three farms had US$ 2.2 < EPO < US$ 4.7 per metric ton of milk, and others had EPO > US$ 4.7 per metric ton of milk as shown in Fig. 1. Among study herds, only one farm had the lowest economic premium opportunity (EPO = 0) because the farm could reduce the TBC (less than 300,000 cfu/ml) and earned the highest economic premium payment (US$6.20 per metric ton of milk) by adopting the most appropriate management practices and observing health factors. However, two farms had the weakest performance due to the highest level of TBC and EPO. Not only did those farms not receive any economic premium benefit, but some economic penalties were also imposed due to the high TBC level caused by not observing health and management practices.

Characteristics and management practices of farms with minimum and maximum economic premium opportunity for TBC are presented in Table 3. These farms were similar in their barn hygiene, frequency of milk delivery, and material of milking parlor wall. But the major differences between farms with minimum and maximum economic premium opportunity for TBC were in herd size (2200 vs. 30 heads), bedding material (sand vs. combined), presence of vet (on-farm vs. part-time), water quality control (less than a year vs. more than a year), frequency of cleaning water troughs (three times a day vs. once a week), and udder washing material (wet tissue vs. warm water), teat cleaning material (wet tissue vs. tissue paper), having a hospital pen (yes vs. no), frequency of calving area disinfection (once a day vs. twice a week) and education level of workers (secondary education vs. illiterate).

Table 3

Characteristics and management practices of farms with minimum and maximum economic premium opportunity for Total Bacterial Count (TBC)
Management factors	Minimum economic premium opportunity	Maximum economic premium opportunity
Herd size (adult cows)	2200	30
Bedding material	Sand	Combined
Presence of veterinarians	On-farm	Part-time
Frequency of milk delivery	More than once a day	More than once a day
Water quality control	Less than a year	More than a year
Frequency of cleaning water troughs	Three times a day	Once a week
barn hygiene	Clean	Clean
Udder washing material	Wet tissue	Warm water
Teat cleaning material	Wet tissue	Tissue paper
Having a hospital pen	Yes	No
Frequency of calving area disinfection	Once a day	Twice a week
Education level of workers	Secondary education	Illiterate
Material of milking parlor wall	Tile	Tile

Bacterial count is one of the chief factors in milk pricing and directly influences milk sales revenue. In this study, we attempted to provide an insight for dairy producers on economic premium opportunities associated with TBC under different management practices to reduce TBC of herds and achieve higher economic benefits. The median bulk tank TBC and the average economic premium opportunity for the sample herds were 298,930 cfu/mL and US$ 1.32 per ton of milk, respectively. Some of the management practices associated with low TBC and high economic bonus included herd size, bedding material, presence of vet, milk delivery to the processor multiple times per day, water quality control, frequency of cleaning water troughs, barn hygiene, udder washing material, teat cleaning material, having a hospital pen, frequency of calving area disinfection, education level of workers and material of milking parlor wall.

Acknowledgments

The authors are grateful to the farmers for participating in the study and to the Solico Kalleh for generously providing the data.

Authors’ contributions

All authors contributed to the study conception and design. Data collection and analysis were performed by Fatemeh Soleimani-Rahimabad, Ali Sadeghi-Sefidmazgi, and Rabea Rahbar. The first draft of the manuscript was written by Fatemeh Soleimani-Rahimabad and Ali Sadeghi-Sefidmazgi. All authors read and approved the final manuscript.

Compliance with ethical standards

Conflict of interest

The authors certify that there are no conflicts of interests among authors and between authors and other people and organizations.

Ethical approval

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.

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Farm Management and Economic Factors Associated with Bulk Tank Total Bacterial Count in Holstein Dairy Herds in Iran

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Abstract

Figures

Introduction

Materials And Methods

Sampling Procedure and Experimental Design

Statistical Analyses

Economic Calculations

Results

Discussion

Conclusions

Declarations

References

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