Fatty acid profiles of transition milk

Transition milk is the milk produced by a cow in the period from the second milking to approximately the fifth day after parturition and represents an important part of the nutrition of a newborn calf. The positive effects of the transition milk on the calf health were proven and could be attributed, among others, to its fatty acid (FA) profile. When automated milking systems are used, cows can determine their own milking frequency. Therefore, this study aimed to evaluate changes in the FA profile of transition milk in dependence on the number of milkings, parity, and the interval between milkings when using an automated milking system.
The on-farm observation was carried out on 18 Czech Fleckvieh cows in a private dairy farm. The cows involved in the experiment calved within 3 months (February – April 2022) and were on their first (P1, 7 cows), second (P2, 5 cows), or third and higher parity (P3+, 6 cows). Cows had free access to the automatic milking system (AMS, Lely Astronaut A3, Lely Industries NV, Maassluis, The Netherlands). They were milked in AMS since the second milking (M2), with the maximum number of milkings (M) per day limited to four by the AMS software. The between-milking interval was monitored and classified as Short (< 12 h) or Long (> 12 h). The samples of transition milk were collected since the second milking and during the first four days of lactation until the milk was not saleable. The FA profile of feed and transition milk samples was analyzed using two-dimensional gas chromatography with vacuum ultraviolet detector (GC×GC-VUV).
The FA profile was shown to change gradually with the increasing number of milkings. The relative content of short-chain and long-chain FAs increased at the expense of medium-chain FAs, and the relative content of monounsaturated FAs increased at the expense of saturated FAs. Furthermore, the FA profile in transition milk from the cows during their first lactation was similar to the profile that otherwise characterized the milk at the end of transition. On the other hand, the interval between milkings did not have a pronounced effect on the FA profile. When using automated milking systems, cows’ parity and milking number seem to be the main factors influencing FA profile of transition milk.