Lactation curves for first lactation Egyptian buffalo.

First lactation records of 1538 buffalo maintained at the Animal Production Research Institute farms in 1967 to 1990 were used to determine lactation curves for three lactation lengths: > 28 and < 150 d, > 149 d, and > or = 308 d, as well as all records. Daily milk yields were summed by 14-d intervals for analyses. Yields peaked at the first, fifth, sixth, and seventh periods for > 28 and < 150 d, > 149 d, > or = 308 d, and all records. Herd-year-season significantly affected milk yield in all periods. Persistency for all records and three groupings (> 28 d, > 149 d, and > or = 308 d in milk) was highest for the > or = 308-d group (1.02 vs. .85 for > 149 d, .57 for > 28 d, and .47 for all records). Herd-year-season of calving significantly affected persistency in all records and the three subset groupings. Persistency was higher for buffalo calving in spring and summer for all records, records > 28 d, and records > 149 d but in summer and autumn for the > or = 308 d, the correlation coefficient between persistency and milk yield (r = .06) was not significant but was negative with season of calving (r =-.11).