Scholarship & Research
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Item Does Paid Family Leave Cause Mothers to Have More Children? Evidence from California(Springer Science and Business Media LLC, 2022-05) Golightly, Eleanor; Meyerhofer, PamelaLiterature on the labor market and health effects of paid family leave largely overlooks the impacts on fertility, particularly in the United States. Increased childbearing following the introduction of a modest paid family leave policy in the U.S. could explain the contrasting short–term gains and long–term losses in women’s labor market outcomes found in recent work. We exploit the nation’s first paid family leave program, implemented in California in 2004. Using the universe of U.S. births and a difference-in-differences strategy, we find that access to leave increases fertility by 2.8 percent, driven by higher order births to mothers in their 30s, as well as Hispanic mothers and those with a high school degree. Our results are robust to corrective methods of inference, including synthetic controls. Our findings may inform the discussion of a national paid family leave policy.Item Characterization of non-polar compounds from Pinus ponderosa needles causing reproductive failure in mice during early gestation(Montana State University - Bozeman, College of Letters & Science, 1979) Kubik, Yolanta MiroslawaItem Ruffed grouse productivity and habitat selection at the base of the Beartooth Plateau in southcentral Montana(Montana State University - Bozeman, College of Letters & Science, 1999) Johnson, David EdwardItem Estrogens and progesterone in the posterior vena cava and estrogens in the urine of cattle(Montana State University - Bozeman, College of Agriculture, 1964) Varman, Pran NathItem Sequential changes in some characteristics of two-row barley (Hordeum distichon L., VAR. Betzes) induced by differential irrigation and fertility regimes(Montana State University - Bozeman, College of Agriculture, 1969) Redgrave, David John VaughanItem Age determination, growth, fecundity, age at sexual maturity, and longevity for isolated, headwater populations of westslope cutthroat trout(Montana State University - Bozeman, College of Letters & Science, 1995) Downs, Christopher CharlesItem Changes in temporal leptin concentrations and other metabolic factors in primiparous, postpartum, anestrous, suckled beef cows exposed to bulls(Montana State University - Bozeman, College of Agriculture, 2009) Olsen, Jesse Riley; Chairperson, Graduate Committee: James G. Berardinelli.Exposing cows to bulls or excretory products of bulls stimulates resumption of ovarian cycling activity in postpartum, suckled, anestrous cows. This biostimulatory effect may be mediated by pheromones produced by bulls that stimulate physiological changes in metabolic regulation of the hypothalamic-pituitary-ovarian (HPO) axis of cows. In Experiment 1, the hypotheses tested were that concentrations of glucose, NEFA, thyroxine (T4), tri-iodothyronine (T3), and T3:T4 ratios do not differ between cows exposed to bulls or steers. The biostimulatory effect of bulls was associated with lower mean concentrations of NEFA in postpartum cows. Experiment 2 was designed to determine if continuous (24-h daily) bull exposure alters temporal patterns of leptin concentrations in postpartum, anestrous cows. Cows exposed to bulls that resumed cycling activity after the start of the experiment tended to have higher leptin concentrations by the end of the 30-d exposure period than cows not exposed to bulls. However, it was not known if these changes were related to resumption of ovarian cycling activity in postpartum, anestrous cows. Experiment 3 tested the hypothesis that temporal leptin concentrations may depend upon duration of daily bull exposure. Cows had higher daily leptin concentrations and resumed ovarian cycling activity sooner as duration of daily bull exposure increased. In conclusion, as duration of daily bull exposure increases, the biostimulatory effect of bulls alters temporal leptin concentrations and this change may facilitate or support the function of the HPO axis and accelerate resumption of ovarian cycling activity in primiparous, postpartum, suckled, anestrous cows.Item Effects of ewe late gestational supplementation of rumen undegradable protein, vitamin E, zinc, and chlortetracycline on ewe productivity and postweaning management of lambs on feedlot performance and tissue deposition(Montana State University - Bozeman, College of Agriculture, 2009) Redden, Roy Reid, 1981-; Chairperson, Graduate Committee: Patrick G. Hatfield.Lamb survival and productivity from birth to weaning and lamb postweaning management harvest are areas that the US sheep industry needs to become more efficient at to remain profitable. Western white-faced ewes were supplemented HIGH (12.5% rumen by-pass protein, 880 IU/kg of supplemental Vitamin E, 176 ppm chelated Zn, and 72.7 mg/kg chlortetracycline) or LOW (7.56% rumen by-pass protein, with no supplemental Vitamin E, chelated Zn, or chlortetracycline) supplements at 0.227 kg·ewe -1·d -1 during late gestation. Ewes of different age and body condition scores were individually supplemented for 29 d prior to expected lambing. Thereafter, each ewe was mass fed the appropriate supplement until lambing. In Experiment 3, approximately 600 ewes were group fed HIGH or LOW supplements over 2 yr. Differences in antibody transfer from ewe to lamb were detected in supplemented ewes of different age (P < 0.10); however, lamb production was not different (P > 0.10) for all 3 experiments. To investigate lamb post-weaning management, terminally sired lambs (n = 72) were randomly assigned to 1 of 4 backgrounding treatments. Lamb backgrounding treatments were: ad libitum access to 80% alfalfa: 20% barley pellets (PELLET); cool season grass paddock grazing (GRASS); remain with ewe flock on fall dormant range (LATE WEAN); wean for 96 h and returned to ewe flock on dormant range (RANGE). Background treatments were applied for 29 d. Thereafter, lambs were finished on a corn based diet. Lamb BW and ultrasound measurements were taken at weaning, after background treatment, after feedlot step-up and at the conclusion of the finishing period. Pen intake was measured. Lambs backgrounded on PELLET were heavier (P < 0.10) than all other treatments after the backgrounding period and at the end of the feedlot period. Lambs backgrounded on PELLET had the greatest intakes and ADG (P < 0.10) during the feedlot period. At beginning and end of the feedlot period, PELLET and GRASS lambs had larger (P < 0.05) LM areas than RANGE and LATE WEAN treated lambs. Under the condition of the studies, late gestational supplements did not improve ewe productivity and backgrounding treatments on dormant range diminished feedlot productivity.Item The biostimulatory effect of bulls on postpartum follicular wave development in postpartum, anestrous, suckled beef cows(Montana State University - Bozeman, College of Agriculture, 2009) Wilkinson, Jarrod Robert Charles; Chairperson, Graduate Committee: James G. Berardinelli.The objective of this experiment was to determine if bull exposure influences follicular wave dynamics in primiparous, postpartum, anestrous, suckled, beef cows exposed to bulls. In Experiment 1, cows were exposed (continuously 24 h/d), (EB; n = 5) to bulls or not exposed to bulls (NE; n = 5) throughout the experimental period. In Experiment 2, cows were exposed to bulls for either 12 h, (EB12; n = 15), 6 h, (EB6; n =14) or not exposed to bulls (NE; n = 10) from the start to the end of the experimental period. In Experiments 1 and 2, cows were 67 d ± 3.8 (mean ± SE) and 51.5 ± 2.3 d postpartum at the start of the experiment. Follicular characteristics of each cow were examined by transrectal ultrasonography. In Experiment 1, interwave interval for wave 3 was shorter in EB than NE cows. Maximum dominant follicle (MDF) diameter tended to be greater during wave 2 for EB than NE cows, while wave 3 was greater for EB than NE cows. However, MDF diameter for wave 6 was greater for NE than EB cows. In Experiment 2, EB12 cows had fewer follicular waves to the resumption of luteal activity (RLA) than NE cows, while the number of waves to RLA for EB6 cows did not differ from that of EB12 or NE cows. Normalizing follicular waves to the time of RLA for cows within the EB12 and EB6 indicated that those cows at RLA had larger MDF diameters for the wave that produced the ovulatory follicle than cows that did not RLA. These data show the effects of bull exposure in altering follicular growth and developmental patterns, shortening the inter-wave interval and increasing the MDF diameter. Though the mechanism through which bull exposure alters postpartum follicular development is not entirely understood, these data provide new understanding.