DETERMINANTS OF UDDER QUARTER MILK YIELD IN AUTOMATICALLY MILKED COWS

The objective of this paper was to analyse udder quarter milk yield in automatically milked cows, taking into account the lactation number, lactation period and season, as well as to determine the share of individual quarters (front and rear quarters, left and right quarters) in total milk yield during a single milking. The analysis was conducted using data obtained from one cattle farm with 280 Polish Holstein-Friesian (PHF) cows, milked with 4 VMS milking robots. The analysed parameters included: milk yield during milking of front quarters (left and right), rear quarters (left and right), the ratio of front quarter to rear quarter and left to right quarter yields. In the oldest cows, an increase was observed in udder quarter milk yield in lactations 1–3, followed by a decrease in lactation 4 and then another increase. Cows in lactations ≥5 have better milk yield than cows in the 3rd lactation. An average milk yield of one quarter of the udder for all lactations was 3.81 kg. With higher lactation numbers, there was a decrease in milk yield for all udder quarters. The reduction in udder quarter milk yield of lactating cows ranged from 1.52 kg (rear right quarter) to 1.78 kg of milk (rear left quarter) and from 1.59 kg (front right quarter) to 1.70 kg of milk (front left quarter). No significant differences were observed in the milk yield of individual udder quarters in the spring, summer and autumn seasons. On the other hand, there was a marked increase in this parameter in the winter months. With successive lactations, the share of front quarters in total milk yield decreased – from 46.9% in primiparous cows to 41.2% in cows after ≥5 lactations. The share of rear quarters in milk yield in turn increased. With every successive lactation, the disproportion in the milk yield between the front quarters and rear quarters widened. When it comes to the left and right quarters of the udder, in terms of the factors considered, similar results were observed.