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    Comparative evaluation of major milk quality parameters of Holstein and Simmental cows at different lactation stages under similar environmental conditions
    (Polish Soc Veterinary Sciences Editorial Office, 2023) Kaya, Ufuk; Ozkan, Huseyin; Yazlik, Murat Onur; Camdeviren, Baran; Gungor, Guven; Karaaslan, Irem; Dalkiran, Sevda
    The aim of this study was to evaluate the composition and quality parameters of Simmental and Holstein cows' milk with different lactation stages under the same environmental conditions. Multiparous Holstein and Simmental cows from different lactation stages (n = 210) were included in the present study. MDA, SCC, composition, and fatty acid analyzes were performed from the collected milk samples. To determine the effect of breed, lactation stage and their interactions, linear mixed models were applied to these parameters. Among the breeds, only milk fat and pH were determined statistically significant as composition parameters. While C15:0 and C17:1 n8 were observed to be statistically significant for the breed factor, C18:2 n6 trans were statistically significant only for the lactation stage factor. Moreover, the fatty acids of C4:0, C6:0, C8:0, C10:0, C11:0, C12:0, C13:0, C16:0, C18:1 n9, C20:0 and C22:6 n3 were determined to be statistically significant in terms of interactions. For the fatty acid indices, SCFA, MCFA, n3 and n6/n3 were statistically significant in terms of interactions while SFA, MUFA, UFA and AI were statistically significant in terms of breeds. On the other hand, new studies are needed to investigate the differences between these breeds at the molecular level for milk quality and fatty acid synthesis.
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    Diagnostic accuracy of milk components for pregnancy diagnosis in mid and late lactation cows
    (Croatian Dairy Union, 2023) Kaya, Ufuk; Yazlik, Murat Onur; Ozkan, Huseyin; Camdeviren, Baran; Gungor, Guven; Dalkiran, Sevda; Keceli, Hasan Huseyin
    The aims of this study were to establish a cut-off point by evaluating the usability of the somatic cell count (SCC) and milk components (fat, fat-free dry matter (FFDM), protein, lactose, freezing point, electrical conductivity and pH) to observe the pregnancy status, and to determine the practical usage of these parameters as diagnostic biomarker of pregnancy status. In the present study, primiparous Holstein cows (n=133) were included in the mid and late lactation. Milk samples were collected in sterile tubes for SCC and milk components analysis. In each lactation period, SCC, milk yield and milk component parameters were analysed by Student's t test according to pregnancy status. Receiver operating characteristic curves were used to determine the predictive threshold using SCC and milk component parameters to discriminate between pregnant and non-pregnant cows. SCC levels were similar for all cows in the mid and late-lactation. In the mid lactation, FFDM, protein, lactose and electrical conductivity were higher and milk yield, fat, freezing point and pH were lower in pregnant cows (p<0.05). In the late lactation, FFDM, protein, lactose and electrical conductivity were significantly higher and milk yield, fat and pH were significantly lower in pregnant pH were the best predictors for pregnancy diagnosis in mid-lactating cows with the AUC values of 0.840, 0.768, 0.780, 0.772, 0.693, 0.792, and 0.901 respectively. Furthermore, fat, FFDM, protein, lactose, electrical conductivity, and pH could be useful diagnostic tools for pregnancy determination in late lactating cows with the AUC values of 0.869, 0.684, 0.661, 0.689, 0.756, and 0.841 respectively. In conclusion, the milk components could be used as rapid, easily accessible, and inexpensive markers for the evaluation of the diagnosis of pregnancy status in primiparous Holstein cows.