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Twenty-eight cows were assigned randomly to a daily photoperiod of 18 h light and 6 h darkness or to continuous light and were observed 1 day each month from December 1981 to February 1982. Lighting regimen did not affect eating behavior or milk production. Overall means of total eating time, number of eating bouts, and average time eating per bout on the 3 observation days were 270 to 280 min, 10 to 12 times, and 24 to 27 min. Eating behavior and milk production were not significantly correlated. Eating patterns were similar in both groups and across observation days. Peaks of eating activity occurred before sunset, bracketing the evening milking and after the offering of fresh feed in the morning. Approximately 80% of total eating activity occurred between 0900 and 2100 h in both groups. Cows had a clear preference for entry into the right or left side of the milking parlor, and entry order was repeatable. Milking order and milk production were not correlated. In one group, location of free stalls did not influence utilization; but in the other group, centrally located stalls were utilized more than stalls at either end of the alley. About 40% of cows had individual free stall preferences.

Statistical properties, inheritance of spermatozoan midpiece length, and its association with bull reproductive traits and daughters' dairy traits were examined in a sample of 39 Holstein bulls. Variation for midpiece length of individual cells was small within bulls (coefficient of variation ⋍ 4.5%), but midpiece length did vary among bulls. Average midpiece length did not differ in ampules of semen collected from the same ejaculate but did differ between ampules of semen from the same bull collected at least 6 mo apart. Two methods of estimation yielded heritabilities of midpiece length greater than one. Both were imprecise but consistent with additive genetic variation for the trait. Moderate correlations between a sire's midpiece length and his Predicted Difference for dairy production traits were negative. Correlations between midpiece length and semen quality and fertility were close to zero. Results suggest that midpiece length is heritable and that it might be correlated with economically important dairy production traits.