Abstract
Serum concentration of estrone (E1) and estradiol (E2) were quantitated during the postpartum interval of suckled (S) and non-suckled (NS) primiparous heifers. Ovarian and uterine changes, estrus and ovulation were also recorded during this period. Then 2-year-olds primiparous Hereford heifers were randomly divided into two groups of five S and five NS animals. The calves of the NS group were removed at birth while those of the S groups were allowed to suckle four times daily until satiated. Blood samples were collected at 6-hour intervals from parturition to estrus, and observations for standing estrus conducted six times daily. The animals were palpated every other say and fed according to NRC recommendations. The nutritional status was monitored by recording individual animal weights at approximately 2-week intervals. The group means of each animal's prepartum and postpartum daily gain were within the recommendations reported necessary to avoid a delayed return to reproductive activity due to nutritional stress.
Conner, Jack Seale (1976). Serum estrone and estradiol from parturition to estrus and ovulation in suckled and nonsuckled primiparous Hereford heifers. Doctoral dissertation, Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -182548.