Machine milking of Istrian dairy crossbreed ewes: udder morphology and milking characteristics

摘要

The objective of this study was to evaluate the differences in udder morphology and milking characteristics between Istrian dairy crossbreeds. A total of 63 Istrian dairy crossbreed ewes (12 crosses with 75% Istrian and 25% Awassi, IAI; 14 crosses with 25% Istrian, 25% Awassi and 50% East Friesian, IAEF; 37 crosses with 50% Istrian and 50% Awassi, IA) were used in the experiment. Ewes were milked twice daily up to day 149 of lactation. Thereafter, they were milked once a day until the end of lactation (150-250 days). Udder morphology was evaluated in mid-lactation (90-120 days). The traits measured were udder volume, teat length and teat angle. Milk flow recordings by using a specially calibrated mobile system for ewe milking (Lactocorder) were performed in early (month 2), mid (months 3-4) and late (months 6-7) lactation. Overall milk yield was 292 10 kg during 203 4 days of lactation in all crosses. The estimated average daily yield was 1.4 +/- 0.1, 1.4 +/- 0.1 and 1.6 +/- 0.1 kg per day for IAI, IA and IAEF crosses, respectively. Milk flow curves with one peak were mainly present in IAEF crosses, while IAI and IA crosses had an equal distribution of milk flow curves with one and two clearly separated peaks. Milk flow curves with diffuse shape and peak flow rate below 0.4 kg/min were equally low in all animals (8-11%). Udder traits in all animals were 1.2 +/- 0.11, 3.3 +/- 0.1 cm and 46 +/- 1degrees for udder volume, teat length and teat angle, respectively. Milking characteristics were 1.7 +/- 0.4 min, 0.6 +/- 0.2 kg, 0.7 +/- 0.2 kg/min and 0.4 +/- 0.1 kg/min for milking time, milk yield, peak flow rate and average flow rate, respectively. Milking characteristics were mostly positively correlated (P < 0.001), except for milking time and average flow rate (r = -0.30, P < 0.05). Moreover, udder volume was positively and significantly (P < 0.001) correlated with all milking characteristics. Peak flow rate tended (P = 0.08) to be higher in IAEF compared to IAI crosses. Udder volume increased with lactation number. Istrian dairy ewe crosses are well adapted to machine milking. The milk production tended to be higher in IAEF crosses compared to IA and IAI crosses.