Preliminary Observations on Milk Flow and Udder Morphology Traits of East Friesian Crossbred Dairy Ewes

Milk yield, milk flow, and udder morphology traits were measured in 72 East Friesian crossbred multiparous ewes to estimate the variation in milk flow patterns present in this research flock, and to asses the repeatability of these measurements and their relationships with other lactation traits. A special milk flow apparatus designed for dairy ewes was used on two consecutive morning milkings at approximately 90 d in lactation to measure milk yield and flow rates. Udder morphology and teat placement traits were measured 4 hr prior to the evening milking. From the original 72 ewes, 48 of them were measured every two weeks during their fourth and fifth months of lactation with the milk flow apparatus only. Milk yield traits measured included: machine milk yield and time (the amount of milk extracted by the machine only); stripping yield and time (milk extracted by the milker during stripping); and total milk yield and time. Milk flow traits measured included: milk flow latency (the time it took for milk to begin to flow); maximum milk flow rate; and the time at which maximum milk flow occurred. From the milk yield and milk flow data, calculations were made to estimate average milk flow rate (total milk yield/total milking time), stripping percentage (stripping yield/total milk yield), and machine milking efficiency (machine milk yield/total milking time). The average ewe during mid-lactation yielded 1.14 L of milk in 2.25 min at the morning milking. Of the total milk, 20% of it was extracted by the milker during stripping. Rumination occurred in 93% of the ewes during machine milking. Milk flow traits had good estimates of repeatability between consecutive test days, and reasonable estimates of repeatability as lactation progressed. Machine milking efficiency was significantly positively correlated to maximum milk flow and average milk flow, and significantly negatively correlated to milk flow latency and stripping percentage. Cistern height and teat position score were positively correlated with stripping percentage and negatively correlated with machine milking efficiency. Regression analyses for some of the milk flow traits on machine milking efficiency indicate that average milk flow rate and stripping percentage can be used together to estimate machine milking efficiency. Bimodal or “two-peak” milk emission was observed in 43% of the ewes. These ewes had significantly higher machine milking efficiency, higher maximum milk flow rate, shorter milk flow latency, and shorter milking times. We conclude that this flock of experimental East Friesian-crossbred ewes is well adapted to machine milking and milk flow measurements along with subjective udder morphology scores appear to be reliable techniques for evaluating machine milking efficiency.