Arch. Tierz., Dummerstorf 49 (2006) Special Issue, Department of Cattle Breeding, University of Technology and Agriculture, Bydgoszcz, Poland

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1 Arch. Tierz., Dummerstorf 49 (2006) Special Issue, Department of Cattle Breeding, University of Technology and Agriculture, Bydgoszcz, Poland WOJCIECH NEJA and ANNA SAWA Cytological quality of milk from cows kept in different types of pens, according to the season of the year Abstract A total of 1947 farms from the Pomerania and Kujawy regions were analysed for the effect of type of pen (with or without litter) on the cytological quality of milk, taking into account the season of the year in the statistical calculations. It was found that in most barns, cows were kept in shallow litter stalls. Regardless of the season of the year, milk of the highest cytological quality was obtained from cows kept in pens on litter. Regardless of type of pen and type of litter, the highest proportion of samples with the SCC indicating clinical or subclinical mastitis was found from September to November. Key Words: cow milk, somatic cells, housing with or without litter Introduction Mastitis is the most common and the most expensive disease of cows (KOSSAIBATI and ESSLEMONT, 1997; RAJALA-SCHULTZ et al., 1999; MALINOWSKI and KŁOSOWSKA, 2000). One of the indicators of udder health is milk SCC (MALINOWSKI, 2001), which is also an important criterion of grading the milk purchased from farmers. Changes in the SCC are affected by season of the year, management and milking conditions, age of cows or stage of lactation to a much lower extent than by mastitis. The results of many studies (DORYNEK and KLIKS, 1998; BRZOZOWSKI et al., 1999; BORKOWSKA and JANUŚ, 2001; SAWA and PIWCZYŃSKI, 2002; STENZEL et al., 2002; STENZEL et al., 2003) have shown that milk SCC increases in summer and autumn compared to spring and winter, when it is the lowest. BRZOZOWSKI et al. (1999) attribute this phenomenon to strong seasonality of calvings and greater susceptibility of cows to udder inflammation during the summer period. MALINOWSKI (1996) reports that udder inflammations in summer are favoured by high air temperature and heavy rainfall. The latter encourages the breeding of flies, which prefer hairless skin of the teats when attacking cattle, thus spreading pathogens. In the studies of GRODZKI et al. (1998) and BARŁOWSKA et al. (2003), the spring-summer season proved more favourable in terms of the SCC. The authors attributed this to better hygienic conditions of summer management when cattle spend most of the day on pastures, in contrast to indoor housing in the winter. When discussing the hygienic quality of milk, focus is made on the technological aspects of dairy cow management, including the type of stall and litter used. Litter is the main breeding ground for fungi, which may be a cause of mastitis. They can easily proliferate in old, moist straw and in sawdust (MALINOWSKI, 1997). In the studies by GRODZKI et al. (2002) in 109 analysed farms, shallow litter pens accounted for 89.8%, shallow pens without litter for 8.3%, and deep litter pens for 1.9%. In the studies by LUDWICZUK (2001) conducted on 100 pens, there were 24% deep litter pens and 76% shallow litter pens. The same author states that it is much more laborious to maintain cow hygiene in buildings with deep litter pens than in buildings with shallow litter pens. In the former Zamojskie province in the years 1997/1998, most pens (90%) were shallow, with only 5% of deep litter pens and 5% of deep-litter loose pens (5%) (BORKOWSKA et al., 1998). The studies of GÓRSKA et al. (1999),

2 239 in which the percentages of particular management types were more proportional, indicate that in shallow pens there were more (80%) cows giving milk with less than 500,000 somatic cells per 1 ml than in deep litter pens (75%). The findings of GÓRSKA et al. (1999) show that the proportion of cows giving milk with less than 500,000 somatic cells per ml was higher in shallow pens than in deep-litter pens (80% vs. 75%). The aim of the present study was to analyse the cytological quality of cow s milk depending on the season of the year and management conditions in pens with or without litter, based on large material concerning milk SCC that was routinely collected as part of the milk testing scheme. Material and Methods The study involved 1947 farms in which cows were evaluated for milk performance. Using the questionnaire method, animal specialists gathered housing conditions data on shallow litter pens with straw, shallow litter pens with sawdust, deep litter pens with straw, pens with sand and without litter, and pens with mattresses and without litter. The SYMLEK system provided data on the SCC in samples of milk from test milkings carried out from June 2001 to May SCCs were transformed using the natural logarithm (LnSCC). In the statistical analysis, the average LnSCC value was calculated in relation to management conditions. The significance of differences between means was calculated using Duncan s test. The chi 2 test [SAS/STAT 1995] was used to analyse, depending on the above management conditions and seasons of the year (December-February, March-May, June-August, September-November), the frequency of milk samples in which the SCC per ml of milk was 100,000, 100, ,000, 200, ,000, 400, ,000, 500,001-1,000,000 and >1,000,000. The above classification of milk samples served as a basis for evaluating udder health status (according to RENNER, 1975, with our own modifications) as very good, good, at risk, latent changes, subclinical changes, and clinical changes. Results Analysis of data in Table 1 shows that shallow litter stalls were the most common in Pomerania and Kujawy farms, with 9% of deep litter pens and only 0.6% of stalls without litter. This shows a significant disproportion in the number of analysed farms with cows housed in different systems. Therefore, the results obtained are considered preliminary despite the statistically significant effect of the type of pen on the cytological quality of milk. The type of stall was shown to have a significant effect on LnSCC. Highest quality milk was obtained when the cows were kept in shallow litter pens with sawdust (LnSCC=11.9) and straw (LnSCC=12.2). The cytological quality of milk from cows in deep litter pens was significantly poorer compared to shallow litter pens. The SCC was clearly the highest in the milk of cows kept in pens without litter. It was also found that the type of stall resulted in statistically significant differences ( xx ) in the proportion of milk samples, especially those with the lowest (<100,000) and highest (>1,000,000) SCC per ml of milk. The highest (39%) proportion of milk samples with the low SCC was obtained when cows were kept in shallow litter pens with sawdust, and the lowest (24%) in pens without litter and with

3 240 sand. In the pens in which straw was used as litter, the proportion of milk samples indicative of very good udder health was 30%, regardless of whether the pen was shallow or deep. The proportion of milk samples indicative of subclinical or clinical mastitis was the lowest in shallow litter pens, slightly higher in deep litter pens, and the highest in pens without litter. Analysis of the effect of season of the year on the frequency of milk samples with particular SCCs showed that the worst situation occurred in autumn (only 28% of the samples indicative of very good udder health and almost 14% of the samples indicative of clinical mastitis) (Tab. 2). In summer, the proportion of milk samples with SCC of <100,000/ml was the highest (32%), with a relatively high (13%) proportion of samples with more than 1,000,000 somatic cells per ml milk. The results obtained for samples taken in spring were similar to those found in winter and indicate that very good udder health was found in 30% of the cows, with 12% of the cows having clinical mastitis. Table 1 Effect of stall and litter type on the proportion of cow s milk samples with low and high somatic cell counts Type of stall and litter No. of No. of LnSCC Percentage of milk samples with SCC (thous./ml) of: cowhouses milk samples >1000 Shallow litter straw A Shallow litter A, B, C, D sawdust Deep litter straw A, B Without litter sand A, B, C Without litter A, B, D mattress Total A, B, C... values marked with the same letters differ highly significantly at P 0.01 Analysis of the results concerning the effect of season of the year and cow management system on the frequency of milk samples with particular SCCs shows that the greatest variation occurred in the autumn (chi2=202 xx ) and the lowest in the winter (chi2=123 xx ) (Tab. 2). Compared to the other seasons, in the autumn there was the highest proportion of milk samples indicative of clinical mastitis. This particularly concerned shallow litter pens with sawdust (21.3%) and pens without litter and with sand (21.3%). A similar situation occurred for the proportion of milk samples indicative of subclinical mastitis. It is hard to interpret the high proportion of milk samples with more than 1,000,000 somatic cells per ml, found in the autumn period in shallow pens in which sawdust was used as litter, especially since milk of the highest cytological quality was obtained in these pens in the other seasons of the year. Probably, this was due to a small number of shallow-litter pens with sawdust, and thus a small number of milk samples analysed. Analysis of the milk samples with the lowest SCC showed that the best situation occurred in pens in which straw was used as a bedding. When evaluating the effect of type of stall on the cytological quality of milk in winter, spring and summer, the worst conditions were found in pens without litter (the lowest proportion of milk samples from cows with healthy udders and the highest proportion of milk samples from cows with clinical mastitis). In the above seasons of the year, the most desirable proportion of milk samples (the greatest number of high quality samples and the lowest number of poor quality samples) was from cows kept in shallow litter stalls.

4 241 Discussion Our results confirmed those of the other authors who reported that in the majority of Polish farms, cows are kept in shallow litter buildings (LUDWICZUK, 2001; GRODZKI et al., 2002; GÓRSKA et al., 2003). WINNICKI et al. (2004) estimate that in Poland 97.1% of the barns have shallow litter stalls, 19.2% have deep litter stalls, and only 1.8% have no litter. The results of the above analyses indicate that because of the potential for production of milk of high cytological quality, shallow litter stalls are the most desirable, followed by deep litter stalls and stalls without litter. Studies by MAJCHRZAK and PEŁCZYŃSKA (1997), MAJEWSKI and TIEZTE (1990) and GÓRSKA et al. (2003) indicate that cows kept in shallow stalls were characterized by better udder health and their milk contained less bacteria and somatic cells. GULIŃSKI et al. (2002) showed that housing cows in shallow stalls caused a marked increase in the percentage of extra class milk. According to KARRER (2001), udder hygiene is better when using a mattress rather than a mat for lying. Table 2 Effect of season of the year and type of stall and litter on the proportion of samples of cow s milk with low and high somatic cell counts Percentage of milk samples with SCC (thous./ml) of: Season of the year XII-I Type of stall and litter No. of samples > 1000 Total Shallow litter straw Shallow litter sawdust Deep litter-straw Without litter sand xx Without litter mattress Total III-V Shallow litter-straw Shallow litter sawdust Deep litter straw Without litter sand xx Without litter mattress Total V-VIII Shallow litter straw Shallow litter sawdust Deep litter straw Without litter sand xx Without litter mattress Total IX-XI Shallow litter straw Shallow litter sawdust Deep litter straw Without litter sand xx Without litter mattress It was shown that the cytological quality of milk was differentiated by the season of the year, with the poorest quality milk obtained in the autumn regardless of the housing conditions. The results of studies by other authors (DORYNEK and KLIKS, 1998; GRODZKI et al., 1998; KWAŚNICKI et al., 2003) on the effect of season of the year on milk SCC are inconclusive. The lower SCC (DORYNEK and KLIKS, 1998; BRZOZOWSKI et al., 1999) found in the winter and the higher SCC found in the summer probably result from the increased incidence of mastitis in the summer months, because high temperature stress can increase the susceptibility of cows to

5 242 infection, while humidity related to high temperature makes it easier for microorganisms to proliferate (SMITH and HOGAN, 1996). Our study confirms the findings of GRODZKI et al. (1998), who showed that the spring-summer season was more favourable in terms of milk SCC. Conclusions Most cows were kept in shallow litter stalls. These stalls had a favourable effect on the cytological quality of milk. Regardless of the season of the year, milk of the highest cytological quality was obtained from cows kept in pens on litter. Regardless of type of pen and type of litter, the highest proportion of milk samples with SCC indicative of clinical or subclinical mastitis was found from September to November. References BARŁOWSKA J.; LITWIŃCZUK, Z.; KRÓL, J.; FLOREK, M.; TETER, U.: Wpływ sezonu i rejonu produkcji na skład chemiczny, zawartość mocznika i jakość cytologiczną mleka krów z rejonu Lubelszczyzny i Bieszczad. Zesz. Nauk. Przeg. Hod. 68 (2003), BORKOWSKA, D.; JANUŚ, E.: Wpływ czynników pozagenetycznych na wydajność i skład mleka oraz liczbę komórek somatycznych. Rocz. AR Poznań, Zoot. 53 (2001), BORKOWSKA, D.; RÓŻYCKA, G.; SZTOJKO, D.: Warunki produkcji mleka w gospodarstwach indywidualnych województwa zamojskiego. VI Szkoła Zimowa, Fundacja Ratowania Fauny i Flory Karpat i Podkarpacia. (1998), BRZOZOWSKI, P.; LUDWICZUK, K.; ZDZIARSKI, K.: Liczba komórek somatycznych w mleku krów objętych oceną użytkowości mlecznej w Polsce Centralnej. Zesz. Nauk. Przeg. Hod. 44 (1999), DORYNEK, Z.; KLIKS, R.: Wpływ wybranych czynników na kształtowanie się liczby komórek somatycznych w mleku krów. Rocz. AR Poznań, Zoot. 50 (1998), GÓRSKA, A.; GULIŃSKI, P.; POPŁWSKA, J.; MRÓZ, B.: Jakość mleka krów utrzymywanych w gospodarstwach indywidualnych województwa podlaskiego. Rocz. Nauk. Zoot., Supl.17 (2003), GÓRSKA, A.; LITWIŃCZUK, Z.; NIEDZIAŁEK, G.: Wpływ wybranych czynników środowiskowych na liczbę komórek somatycznych w mleku krów utrzymywanych w gospodarstwach indywidualnych regionu Podlasia. Zesz. Nauk. Przeg. Hod. 47 (1999), GRODZKI, H.; GRABOWSKI, R.; KARASZEWSKA, A.; ZDZIARSKI, K.: Wpływ sezonu i kolejnych lat oceny mikrobiologicznej mleka na jego jakość. Zesz. Nauk. AR Wrocław, Zoot. 331 (1998), GRODZKI, H.; NAŁĘCZ-TARWACKA, T.; SLÓSARZ, J.; PRZYSUCHA, T.: Zmiany zachodzące w pogłowiu bydła, produkcji i jakości mleka w Polsce w ostatnich latach. Zesz. Nauk. Przeg. Hod. 60 (2002), GULIŃSKI, P.; GIERSZ, B.; MŁYNEK, K.; DZIUDZIK, A.: Uwarunkowania produkcji mleka surowego w gospodarstwach indywidualnych środkowo-wschodniej Polski. Zesz. Nauk. Prz. Hod. 62 (2002), KARRER, M.: Haltungsverfahren beim Milchvieh. Deutsch-Polnisches Seminar der Hans-Seidel-Stifung, Bayerische Landesanstalt für Tierzucht, Grub KOSSAIBATI, M.A.; ESSLEMONT, R.J.: The cost production diseases in dairy herds in England. Vet. J. 154 (1997), KWAŚNICKI, R.; DOBICKI, A.; ŁOZA, A.; MICHAŁOWICZ, D.: Wpływ sezonu na zawartość komórek somatycznych i ogólną liczbę bakterii w mleku krów użytkowanych w trzech rejonach Dolnego Śląska. Zesz. Nauk. Przeg. Hod. 69 (2003), LUDWICZUK, K.: Przyczyny zmienności liczby komórek somatycznych w mleku krów objętych oceną użytkowości mlecznej w województwie warszawskim i siedleckim. Praca doktorska. SGGW, Warszawa MAJCHRZAK, E.; PEŁCZYŃSKI, E.: Wpływ warunków doju na jakość higieniczną mleka. Med. Wet. 53 (1997),

6 243 MAJEWSKI, T.; TIETZE, M.: Wpływ warunków zoohigienicznych na zdrowotność wymion krów i jakość higieniczną mleka. Ann. Univ. MCS, Vol. VIII (1990), MALINOWSKI, E.: Przyczyny, leczenie i zapobieganie mastitis u krów. PIWet, Puławy (1997) MALINOWSKI, E.: Komórki somatyczne mleka. Med. Wet. 57 (2001), MALINOWSKI, E.; KŁOSOWSKA, A.: Stan zdrowia wymienia krów punktem krytycznym w produkcji mleka. Przeg. Mlecz., 9 (2000), MALINOWSKI, E.: Letnie zapalenie wymienia. Med. Wet. 52 (1996), RAJALA-SCHULTZ, P.J.; GROHN, Y.T.; McCULLOCH, C.E.; GUARD, C.L.: Effects of clinical mastitis on milk yield in dairy cows. J. Dairy Sci., 82 (1999), RENER, E.: Investigations on some parameters of milk for the detection of subclinical mastitis. Proc. Semin. Mast. Cont. IDF Doc SAWA, A.; PIWCZYŃSKI, D.: Komórki somatyczne a wydajność i skład mleka krów mieszańców cb x hf. Med. Wet. 58 (2002), SMITH, K.L.; HOGAN, J.S.: Future prospects for mastitis control. Proc. XIX World Buiatrics Congress. Edinburgh, 1 (1996), SAS\STAT User s guide Version 6,12 Edition, 1995 STENZEL, R.; CHABUZ, W.; CIASTEK, K.: Ilość i jakość mleka pozyskiwanego w różnych systemach utrzymania i dojenia zależnie od pory roku, wieku krów, przebiegu laktacji. Pr. Mater. Zoot. 14 (2002), STENZEL, R.; CHABUZ, W.; CIASTEK, K.; ŻELEZIK, M.: Wpływ wybranych czynników środowiskowych i genotypu na jakość i skład chemiczny mleka pozyskiwanego w gospodarstwach prywatnych Lubelszczyzny. Ann. UMCS Sect. EE, XXI, 1 (2003), Authors address Prof. Dr. habil. ANNA SAWA Dr. WOJCIECH NEJA University of Technology and Agriculture Faculty of Zootechnic, Department of Cattle Breeding, BYDGOSZCZ, Kujawsko-Pomorskie POLAND nejaw@atr.bydgoszcz.pl