Effect of various forms of mastitis on milk quantity and composition for 305-day lactation in cows
2007
Petkov, P. | Dimitrov, F. | Koleva, M.
A total of 273 cows are included in the study in I, II and III lactation, reared on 4 farms. They are of the Bulgarian black-and-white breed and are the daughters of 39 bulls. The aim of the study is related to establishing the effect of the various types of mastitis on the quantity of milk yield for 305-day lactation. To determine the disease of various forms of mastitis a total of 1092 milk samples have been taken from the relevant number of udder quarters. During lactation the test has been performed two to three times. According to the mastitis disease cows were grouped as follows: with healthy quarters; with latent infection (LI); with non-specific mastitis (NSM); with subclinical mastitis (SCM) and with clinical mastitis (CM). The features characterizing milk productivity are: quantity of milk yield, kg; milk fat (MF), kg; milk protein (MP), kg; milk fat + milk protein (MF+MP), kg; percentage of fat and percentage of total protein in milk. Only NSM has had reliable effect on the quantitative parameters of milk productivity (milk yield; MF, MP and MF+MP) (P0.01 to P0.01). Subclinical mastitis and NSM have low reliability level of effect respectively on the percentage of fatty matter and the percentage of total protein in milk. From cows whose quarters have been affected by NSM lower milk yield has been obtained from 437 to 937 kg compared to the LS-mean for the model. The difference exceeds 1140 kg compared to cows with healthy udder concerning that type of mastitis. By increasing the number of quarters affected by NSM the percentage of fatty matters in milk decreases, while the % of total protein increases.
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