Studies of Herd Management Records II. Relation of Gestation Length to Birth Weight of Holstein Calves of both Sexes at Various Calvings

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Abstract
A study of 755 normal gestations, 384 male births and 371 female births of Holstein calves in the U. of Nebraska herd during the period 1897-1950 was made to detn. the relationship between length of gestation and birth wts. of calves, by sexes and successive calvings. Gestation length for each sex and for successive calvings showed no significant trend. The avg. gestation length for males was 278.9 days and for females 278.4 days. The avg. birth wt. for males was 96.7 lbs. and for females 90.3 lbs. Analysis of variance showed that differences in birth wt. due to sex, calving sequence, and gestation length were significant (P<0. 0.1), Correlation between gestation length and birth wt. was 0.26, with 99% fiducial limits of 0.28-0.22. The regression of birth wt. on gestation was 0.66 lb./ day.