@article{morbeck_flowers_britt_1993, title={Response of porcine granulosa cells isolated from primary and secondary follicles to FSH, 8-bromo-cAMP and epidermal growth factor in vitro}, volume={99}, DOI={10.1530/jrf.0.0990577}, abstractNote={A cell culture system was developed to study the function of porcine granulosa cells from primary and secondary follicles. Primary follicles were isolated from 1- to 3-day-old pigs. Secondary follicles were isolated from 50- to 60-day-old pigs. Follicles were isolated after a digestion for 15 min with 0.25% trypsin followed by 15 min with 1000 U DNAase. Follicles were plated at 100 primary follicles or 30 secondary follicles per well in 48-well plates and cultured in media containing 10% fetal bovine serum (FBS). During initial plating, follicles attached to the plate and cells spread from the point of attachment. This resulted in monolayer cultures of granulosa cells from primary or secondary follicles. On day 4 of culture, media were replaced with 0.5 ml media containing one of the following treatments: control (media only); 10% FBS; 100 ng FSH; 2 mmol 8-bromo-cAMP l-1 or 50 ng epidermal growth factor (EGF). Media and cells were harvested on day 6, after 2 days of treatment. FBS and EGF increased DNA in granulosa cell cultures from primary or secondary follicles (P < 0.01). Treatment with 8-bromo-cAMP increased DNA in granulosa cell cultures from primary but not from secondary follicles (P < 0.05). Conversely, treatment with FSH increased DNA in granulosa cell cultures from secondary but not from primary follicles (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)}, number={2}, journal={Journal of Reproduction & Fertility}, author={Morbeck, D. E. and Flowers, W. L. and Britt, J. H.}, year={1993}, pages={577} }
 @article{morbeck_esbenshade_flowers_britt_1992, title={KINETICS OF FOLLICLE GROWTH IN THE PREPUBERTAL GILT}, volume={47}, ISSN={["1529-7268"]}, DOI={10.1095/biolreprod47.3.485}, abstractNote={Follicular growth rates were determined by histological examination of ovaries of five prepubertal gilts following treatment with the stathmokinetic agent colchicine. One ovary from each of five gilts was removed surgically and then colchicine (n = 3) or saline (n = 2) was infused i.v. Precisely 2 h after treatment with colchicine, the remaining ovary was removed. Ovaries were processed for histological analyses and sectioned at 10 microns; every twentieth section was stained with hematoxylin and periodic acid-Schiffe's. Sections were viewed with a projection microscope and individual follicles were measured. Eight classes of follicles were established such that the number of granulosa cells per cross section doubled in each class. Diameters of follicles for each class were as follows: 1) less than 106 microns, 2) 106-148 microns, 3) 148-206 microns, 4) 206-287 microns, 5) 287-400 microns, 6) 400-657 microns, 7) 657-1480 microns, and 8) 1480-3130 microns. A layer of thecal cells was first seen in class 2 follicles, and 76% of class 3 follicles had a thecal layer. Oocyte diameter increased through the first four classes and reached a maximum diameter of approximately 110 microns. Almost all follicles greater than 400 microns had an antrum. Preantral follicles had a lower mitotic index and a higher mitotic time and class time than antral follicles. Growth rate increased with increasing size of follicles. Preantral follicles grew at a rate of 5.2 microns/day whereas antral follicles grew at 313 microns/day.(ABSTRACT TRUNCATED AT 250 WORDS)}, number={3}, journal={BIOLOGY OF REPRODUCTION}, author={MORBECK, DE and ESBENSHADE, KL and FLOWERS, WL and BRITT, JH}, year={1992}, month={Sep}, pages={485–491} }
 @article{morbeck_tyler_britt_1991, title={DURATION OF ESTROUS CYCLES SUBSEQUENT TO 2 INJECTIONS OF PROSTAGLANDIN-F2-ALPHA GIVEN AT A 14-DAY INTERVAL IN NONLACTATING HOLSTEIN COWS}, volume={74}, ISSN={["0022-0302"]}, DOI={10.3168/jds.s0022-0302(91)78407-5}, abstractNote={Data from previous experiments in our laboratory indicated that estrous cycles following synchronization with two injections of prostaglandin F2 alpha often averaged more than 21 d. To investigate whether this could be an effect of prostaglandin F2 alpha, 54 mature heifers and nonlactating Holstein cows were used in a crossover experiment in which estrous cycles either occurred spontaneously or followed two injections of prostaglandin F2 alpha at a 14-d interval (induced estrus). One estrous cycle of each type was recorded for each animal. Blood samples were collected twice weekly for analysis of progesterone. Cattle were observed twice daily for estrus with the aid of tail chalking and an androgenized cow. Estrous cycles following induced estrus were longer than those following spontaneous estrus (24.2 vs. 22.7 d). Ninety-two percent of the cycles following spontaneous estrus were 17 to 25 d in duration compared with 71% of the cycles following induced estrus. If the first prostaglandin F2 alpha was given when progesterone was greater than 1 ng/ml, the estrous cycle following treatment was longer than if the first prostaglandin F2 alpha was given when progesterone was less than 1 ng/ml (26.0 vs. 22.6 d). This experiment demonstrates that two injections of prostaglandin F2 alpha increase the incidence of estrous cycles greater than 25 d. Stage of the estrous cycle at time of the first injection of prostaglandin F2 alpha may contribute to this effect.}, number={7}, journal={JOURNAL OF DAIRY SCIENCE}, author={MORBECK, DE and TYLER, HD and BRITT, JH}, year={1991}, month={Jul}, pages={2342–2346} }
 @article{morbeck_britt_mcdaniel_1991, title={RELATIONSHIPS AMONG MILK-YIELD, METABOLISM, AND REPRODUCTIVE-PERFORMANCE OF PRIMIPAROUS HOLSTEIN COWS TREATED WITH SOMATOTROPIN}, volume={74}, ISSN={["0022-0302"]}, DOI={10.3168/jds.s0022-0302(91)78388-4}, abstractNote={Thirty-two primiparous Holsteins were assigned to receive 0, 5.15, 10.3, or 16.5 mg/d recombinant bST. Treatment began between 28 and 35 d postpartum and continued until 60 d prior to next expected calving or 400 d postpartum. Metabolic hormones and metabolites were measured in blood weekly during the first 10 wk of treatment, and progesterone was measured in milk twice weekly to assess ovarian activity until conception. Milk production (305 d, actual) was 8350 +/- 562, 8348 +/- 515, 9571 +/- 515, and 9070 +/- 515 for cows given 0, 5.15, 10.3, or 16.5 mg/d and did not differ statistically. Insulin, glucose, NEFA and blood urea nitrogen were not influenced by dose of bST. However, insulin-like growth factor-I increased linearly with dose of bST. Days from parturition to first detected estrus, days open, and services per conception did not differ among groups; however, days from parturition to first service increased with dose of bST. Rate of detection of estrus decreased with dose of bST, resulting in a longer interval to first insemination. The lower rate of detection of estrus in bST-treated cows may have been associated with reduced expression of estrus. Additional statistical analyses were conducted to determine the relationship between metabolism, milk production, and reproduction over all doses of bST. There was a negative correlation between 305-d milk yield and glucose (r = -.44) and insulin (r = -.46) concentrations during 30 to 100 d postpartum. In stepwise regression analyses, insulin accounted for 21% of the variance in 305-d milk yield. Glucose and NEFA accounted for 18% of the variance in days open, and there was a negative correlation (r = -.32) between glucose and days open. Days open and milk production were not correlated.}, number={7}, journal={JOURNAL OF DAIRY SCIENCE}, author={MORBECK, DE and BRITT, JH and MCDANIEL, BT}, year={1991}, month={Jul}, pages={2153–2164} }
 @article{morbeck_mcdaniel_britt_1989, title={Relationships among days open, milk production and metabolism in high producing Holstein cows}, volume={72}, journal={Journal of Dairy Science}, author={Morbeck, D. E. and McDaniel, B. T. and Britt, J. H.}, year={1989}, pages={350} }
 @article{morbeck_mcdaniel_britt_1989, title={Reproductive and metabolic performance of primiparous Holstein cows treated with recombinant bovine somatotropin (rbST)}, volume={72}, journal={Journal of Dairy Science}, author={Morbeck, D. E. and McDaniel, B. T. and Britt, J. H.}, year={1989}, pages={345} }