The impact of genetic and non-genetic factors on somatic cell count as a monitor of udder health in Slovak Simmental dairy cows

Received: 2018-05-18 | Accepted: 2018-05-22 | Available online: 2018-11-26 https://doi.org/10.15414/afz.2018.21.04.166-168 The aim of study was to evaluate the impact of genetic and non-genetic factors on somatic cells count in Slovak Simmental dairy cows in period 2009 to 2013. We observed subsequent results in dairy cows of 55 822 Slovak Simmental cattle. Data were analysed using the SAS and linear model with fixed effects of herd, years and months controls, sire, breeding type. The results of somatic cells count during the years 2009 and 2013 were as follows: the highest number of samples was analysed during 2010 (n = 288 215), where the average count was 560.48*10 3 · ml -1 . The lowest average value of somatic cells count was of amount of 535.93*10 3 · ml -1 (n = 280 732) in 2009.The linear model represents coefficient determination R 2 = 0.038296 % (P<0.001) for SCC with all fixed effects. According to the analyses by the effects on SCC the highest effect was the effect of herd R 2 = 0.021625, then effect of sire R 2 = 0.015075. These effects were highly statistically significant (P<0.001). Correlation coefficients among milk in kg, fat, protein in % with somatic cells count were r = -0.12918, r = 0.04166 and r = 0.11423. These coefficients were highly statistically significant (P<0.001). Keywords: dairy cows, milk production, Slovak Simmental cattle, somatic cells count and coefficient of determination References Alhussien M.N., Dang A.K. (2018) Milk somatic cells, factors influencing their release, future prospects, and practical utility in dairy animals: An overview. Veterinary World, 11 (5), 562-577. DOI:  https://dx.doi.org/10.14202/vetworld.2018.562-577 Boro, P., Naha, B., Prakash, Ch., Madkar, A., Kumar, N., Kumari, A., Prakash Channa, G. (2016) Genetic and non-genetic factors affecting milk composition in dairy cows. International Journal of Advanced Biological Research, 6 (2), 170-174. Ceron-Munoz, M., Tonhati, H., Duarte, J., Oliveira, J., Munoz-Berrocal, M., Jurado-Gamez, H. (2002) Factors affecting somatic cell counts and their relations with milk and milk constituent yield in buffaloes. Journal of dairy science, 85 (11), 2885-2889 https://www.journalofdairyscience.org/article/S0022-0302(02)74376-2/pdf de Freitas, J. A., da Silva, J., FroesGarcezNeto, A., Machado dos Santos, T. (2017) Somatic cell count and milk yield on physicochemical components of milk from free-stall housed cows. Semina: CienciasAgrarias, 38 (2). DOI:  https://dx.doi.org/10.5433/1679-0359.2017v38n2p909 Jadhav, P.V., Tarate, S.B., Bhuvana, M., Das, D.N., Shome, B.R. (2016) Somatic cell count as a monitoring system for hygienic milk production in India: A review. Asian J. Dairy & Food Res., 35, 270-277. Japertienė, R., Anskienė, L., Japertas, S. (2016) Evaluation of the milk production and somatic cell count of Lithuanian purebred and crossbred dairy cows. VeterinarijairZootechnika, 73 (95) Supplement, 51-57. Jattawa, D., Koonawootrittriron, S., Elzo, M. A., Suwanasopee, T. (2012)  Somatic cells count and its genetic association with milk yield in dairy cattle raised under Thai tropical environmental conditions. Asian-Australasian journal of animal sciences, 25 (9), 1216. DOI:  https://dx.doi.org/10.5713/ajas.2012.12159 Oudah, E. Z. M. (2009) Non-genetic factors affecting somatic cell count, milk urea content, test-day milk yield and milk protein percent in dairy cattle of the Czech Republic using individual test-day records. Livestock Research for Rural Development, 21 . Rhone, J. A., Koonawootrittriron, S., Elzo M.A. (2008) Factorsaffecting milk yield, milk fat, bacterial score, and bulk tank somatic cell count of dairy farms in the central region of Thailand. In Tropical animal health and production, 40 (2), 147-153. Saravanan, R., Das, D. N., De, S., Panneerselvam, S. (2015) Effect of season and parity on somatic cell count across zebu and crossbred cattle population. Indian J. Anim. Res., 49, 383-387. DOI:  https://dx.doi.org/10.5958/0976-0555.2015.00127.2 SAS User’s Guide 2002-2003. Version 9.3 (TS1M3). SAS Institute. Inc., Carry. NC. USA. Savic, N. R., Mikulec, D. P., Radovanovic, R. S. (2017) Somatic Cell Counts in Bulk Milk and their Importance for Milk Processing. In: IOP Conference Series: Earth and Environmental Science, 85, p012085. Sharif, A., Muhammad, G. (2008) Somatic cell count as an indicator of udder health status under Modern dairy production: a review. Pakistan Vet. J., 28 (4), 194-200. Souza, G. N., Brito, Jose R. F., Brito, Maria A. V. P., Moreira, Elvio C., da Silva, Marcos V. G. B.(2005) Factors affecting somatic cell counts (SCC) in Brazilian dairy cows. In: Animals and environment. 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Introduction
The somatic cells count (SCC) of milk is widely used to monitor udder health and the milk quality (Sharif, Muhammad, 2008;Jadhav et al., 2016).The composition of milk from dairy cows is of major interest to milk producers, processors and consumers because of its health related issues and also market demand.It directly affects the economy of milk production as well as economic condition of these dairy farmers (Boro et al., 2016).Milk composition can be affected by a wide array of factors: breed, season, age, stage of lactation and diet of the animal (Savić et al., 2017;Tančin et al., 2018).Factors affecting on somatic cells count shows in publications others authors as Cerón-Muñoz et al., 2002;Souza et al., 2005;Rhone et al., 2008;Oudah, 2009;Saravanan et al., 2015 andAlhussien, Dang, 2018.The aim of study was to evaluate the impact of genetics and non-genetics factors on somatic cells count in Slovak Simmental dairy cows.

Materials and methods
The material for evaluation traits in population of dairy cows Slovak Simmental cattle between 2009 and 2013 years were received from of Breeding Service of Slovak republic (B.S. SR, S.E., 2014).We observed subsequent results of 55,822 in dairy cows (1,131,509 control samples) Slovak Simmental cattle: milk in kg (DMY), fat in % (DFC), protein in % (DPC) and somatic cells count (SCC).We according to divided dairy cows a breedtype S 0 -cows with genetic proportion of pure Slovak Simmental blood (into 87.5%), S 1 -cows with genetic proportion of pure Slovak Simmental blood (from 75% to 87.4%), S 2 -cows with genetic proportion of pure Slovak Simmental blood (from 50% to 74.9%).To determine the effect of SCC, it was divided into 4 groups according to the SCC values: I. -up to 100,000 SCC cm -3 ; II.-101-400 SCC cm -3 ; III. -401-500 SCC cm -3 ; IV. -501-1 million SCC cm -3 and V. >1 million SCC cm -3 .The basic statistical analysis of milk production traits and SCC were performed using the Statistical Analysis System (SAS) version 9.3 (TS1M2) Enterprise Guide 5.1.(SAS, 2011).For the actual computation a linear model with fixed effects was used: The aim of study was to evaluate the impact of genetic and non-genetic factors on somatic cells count in Slovak Simmental dairy cows in period 2009 to 2013.We observed subsequent results in dairy cows of 55,822 Slovak Simmental cattle.Data were analysed using the SAS and linear model with fixed effects of herd, years and months controls, sire, breeding type.The results of somatic cells count during the years 2009 and 2013 were as follows: the highest number of samples was analysed during 2010 (n = 288,215), where the average count was 560.48 × 10 3 •ml -1 .The lowest average value of somatic cells count was of amount of 535.93 × 10 3 •ml -1 (n = 280,732) in 2009.The linear model represents coefficient determination R 2 = 0.038296% (P <0.001) for SCC with all fixed effects.According to the analyses by the effects on SCC the highest effect was the effect of herd R 2 = 0.021625, then effect of sire R 2 = 0.015075.These effects were highly statistically significant (P <0.001).Correlation coefficients among milk in kg, fat, protein in % with somatic cells count were r = -0.12918,r = 0.04166 and r = 0.11423.These coefficients were highly statistically significant (P <0.001).

Original Paper
where: μ -mean value H i -effect of herd YS j -effect of years and month of controls b k -sire c l -breeding type e ijklm -residual error

Results and discussion
The basic traits of milk production and somatic cells count (SCC) in evaluated population of dairy cows Slovak Simmental cattle are presented in Table 1.
Figure 1 shows results of SCC by year's evaluation and trends of rising SCC which related with negative correlation among traits of milk production (DMY, DFC and DPC) and SCC.The correlation coefficients among DMY, DFC and DPC with SCC were r = -0.12918,r = 0.04166 and r = 0.11423.These coefficients were highly statistically significant P <0.001 (Table 2).These results are correspondence with Japertienė et al., 2016. De Freitas et al., 2017 shows correlation coefficients among DMY, DFC and DPC with SCC (r = -0.18116,r = 0.09046 and r = 0.08100).
The results of milk traits in control samples by code of SCC were divided into 5 groups and are presented in Figure    Using the linear model we have found out the coefficient determination R 2 = 0.038296% (P <0.001) for SCC with all fixed effects.The analyses by the effect on SCC showed the highest effect of the effect of herd R 2 = 0.021625, followed by the effect of sire R 2 = 0.015075.These effects were highly statistically significant P <0.001 (Table 3).These results are similar with results of Cerón-Muñoz et al., 2002;Souza et al., 2005;Rhone et al., 2008;Saravanan et al., 2015;Boro et al., 2016 andSavić et al., 2017.

Conclusions
The results confirm that the effect of herd on somatic cells count was higher R 2 = 0.021625%, than the effect of sire R 2 = 0.015075%.These effects were significant (P <.0001).For comparison, the correlation among evaluated somatic cells count (SCC) and traits of milk production (milk in kg, fat and proteins in %) were lower and negative r = -0.12918,r = 0.04166 and r = 0.11423.These results were statistical high significant (P <.0001).

Figure 1 Figure 2
Figure 1Estimation of SCC in Slovak Simmentaldairy cows by years of control samples

Table 1
Statistical characteristic of DMY, DFC, DPC and SCC in dairy cows of Slovak Simmental CV -coefficient of variation, Mode -value that appears most often in a set of data, n -number of observation, x --average, SD -standard deviation,

Table 2
Relation between SCC and traits of milk production(DMY, DFC and DPC)