Relationship between milk fat to protein ratio during the postpartum period and calving interval in dairy cows | Povezava med razmerjem med mascobami in beljakovinami v mleku v obdobju po telitvi in dobo med telitvama pri kravah molznicah
2007
Biderman, A., Agricultural Inst. of Slovenia, Ljubljana (Slovenia) | Verbic, J. | Logar, B.
The relationship between fat to protein ratio during the first 100 days of lactation and calving interval (CI) was investigated in dairy cows of various breeds. The study comprised 29.871 lactations, mainly for Black and White breed (13.135 lactations), followed by Brown (8.520 lactations) and Simmental breed (8.216 lactations). It has been established that the wider milk fat to protein ratio and the higher milk production in the first 100 days of lactation resulted in longer CI. The effect of milk fat to protein ratio proved to be more expressed than the effect of milk production. When the milk fat to protein ratio increased for 1 unit, CI was longer for 66 days, 37 and 32 for the primiparous cows of Black and White, Simmental and Brown breed, respectively. For the older cows CI was longer for 54 days, 38 and 42 days for Black and White, Brown and Simmental breed for each unit of increased fat to protein ration in the milk, respectively. The increase of milk production in the first 100 days of lactation for 1000 kg lengthened the CI for 5 days for Brown, and Black and White breed, while for Simmental breed it lengthened the CI for about 8 days. Primiparous cows were characterised by a longer CI than older cows. The month of the beginning of lactation also showed statistically significant effect on CI. In Brown breed CI was the longest if the lactation started in March or April; in Simmental breed if it started in March and in Black and White breed if it started in March, April or May. It has been concluded that dairy cows respond to factors, which widen fat to protein ratio in milk, with longer CI.
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