Semen from four Holstein bulls was evaluated to compare effects of four extender treatments on postthaw semen quality. Extender fractions A and B, either heated whole milk or 20% egg yolk-citrate, were combined to yield the extender treatments 1) milk and milk, 2) milk and egg yolk-citrate, 3) egg yolk-citrate and milk, and 4) egg yolk-citrate and egg yolk-citrate. Semen was evaluated at thawin...

Milk flow measurements on 124 cows were analyzed to deternfine how they are affected by vacuum level, pulsation rate, pulsation ratio of the milking maehine, and the breed, age, stage of laetation, and milk yield of the cow. Average rate of flow prior to machine stripping, yield during the first minute, and yield during the first 2 rain of milking were highly correlated with maxinmm rate of mil...

Diagnostic ultrasound imaging of the breast has been limited principally to the abnormal, non-lactating breast. Due to the rapid improvement of imaging technology, high-resolution ultrasound images can now be obtained of the lactating breast. Ultrasound scanning techniques, however, require modifications to accommodate the breast changes that occur in lactation. Furthermore, the function of the...

The aim of this study was to describe and analyze effects of parity, stage of lactation, milkability (3 groups of cows with differing peak flow rates), time of milking, and quarter position on milk production and milk flow measures at udder and quarter levels. Particular emphasis was put on changes to the decline phase and in duration of overmilking. More than 75,800 quarter milk flow curves an...

Vacuum, b-phase duration, and liner compression are 3 milking machine factors that affect peak milk flow rate; however, extreme values of these factors can also have negative effects on teat tissue health. The main and interactive effects of vacuum, b-phase duration, and liner compression on peak milk flow rate were studied by independently controlling these causal variables over a wide range o...

BACKGROUND Having a poor teat-end condition is associated with increased mastitis risk, hence avoiding milking machine settings that have a negative effect on teat-end condition is important for successful dairy production. Milking-time testing (MTT) can be used in the evaluation of vacuum conditions during milking, but the method is less suited for herds using automatic milking systems (AMS) a...

The rennet activity of chymo-trypsin (or pepsin) is conveniently measured by allowing a standard solution of milk to which chymotrypsin has been added to flow slowly through a graduated pipette and observing the rate and distance of flow of the milk before it clots. The time required for chymo-trypsin to clot milk may be calculated from these observations. The rennet activity is expressed as th...

Milk flow parameters at udder and quarter levels were studied in relation to somatic cell count (SCC) and other risk factors for mastitis (bimodality, duration of decline, and duration of overmilking phase). Thirty-eight Holstein cows in their first to sixth lactations were investigated during 10 mo of lactation. Monthly milk samples were collected for SCC during morning milking. Quarter and ud...

Anatomical and functional characteristics of the teat are supposed to have considerableinfluence on milk flow performance. In the present study various teat and milkingcharacteristics in 148 quarters of 38 cows were analyzed via 3 different approaches. Teatcanal length, teat wall thickness and teat diameter were measured by ultrasound. In addition,the vacuum needed to open the t...

Eight cows underwent Doppler sonographic examinations of the milk vein and musculophrenic vein from 9 days prepartum to 300 days postpartum. A 7.5-MHz linear transducer was used to determine the inner diameter of the veins and blood flow velocities and volumes on the left side in standing, non-sedated animals. Cows were weighed and milk yield measured at all examination times. The milk vein app...