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Item Heifer reproduction strategies: molecular insights into early embryonic development and viability(Montana State University - Bozeman, College of Agriculture, 2022) Manuel, Eden Elizabeth; Chairperson, Graduate Committee: Sarah R. McCoskiCurrent heifer development strategies aim to produce the most fertile female possible. However, in western states heifers commonly transition from high to relatively low nutritional planes following breeding. The effects of maternal nutritive status on the embryonic system are not defined, though this transition is likely contributing to the high rates of early embryonic mortality observed in these animals. This study aimed to decipher the impact of maternal nutrition on day 14 conceptuses collected from beef heifers maintained on ?100% or 70% NRC nutrient requirements. Conceptus RNA was isolated and sequenced to identify differentially expressed genes (DEGs). The DEG set included 771 annotated and 132 novel genes. The biological processes representing the most significant differential expression between conceptuses collected from Low- vs- High groups were hormone metabolic processes (Padj = 0.015), inner ear development (Padj = 0.015), inner ear morphogenesis (Padj = 0.015), hematopoietic progenitor cell differentiation (Padj = 0.015), and tissue morphogenesis (Padj = 0.018). KEGG analysis identified the biological pathways most affected between Low- and High-derived conceptuses. Analysis revealed viral fusion proteins, oocyte meiosis, mineral absorption, and sphingolipid metabolism were significantly affected. Interestingly, the pathways representing the highest number of DEGs were peptidases and inhibitors (n = 22 DEGs), MAPK signaling pathway (n = 17 DEGs), and viral fusion proteins (n = 17). Deeper analysis of the KEGG pathway and gene ontology results linked many of the DEGs to processes related to the cellular differentiation, formation, and function of extraembryonic tissues. While more advanced embryonic patterning and fetal development presented as areas of concern in the literature search, at this time they are not likely factors contributing with the most weight to the high rates of embryonic mortality observed in beef cattle. A majority of the DEGs were related to pathways that control early cell specification events that are necessary for the formation of the trophectoderm and the yolk sac. Data indicates that a decreased plane of maternal nutrition affects the expression of genes associated with critical embryonic events, and likely contributes to increased rates of embryonic mortality by altering the function of extraembryonic tissues.Item The influence of dam age and heifer post-weaning voluntary feed intake on subsequent production, reproduction and lifetime productivity of Angus beef females(Montana State University - Bozeman, College of Agriculture, 2022) Wellnitz, Krista Rose; Chairperson, Graduate Committee: Megan Van Emon and Timothy DelCurto (co-chair); This is a manuscript style paper that includes co-authored chapters.Limited research has been done to evaluate the impacts of dam age or post-weaning voluntary feed intake and its impact on subsequent performance and longevity in the beef herds, specifically female offspring. Therefore, the objectives of this research were to investigate how dam age and post-weaning voluntary feed intake influences lifetime productivity of commercial Angus females. First-calf heifers and mature cows were used to conduct three studies. Results indicate that classification of replacement heifers based on intake as a heifer had little to no impact on subsequent productivity as a mature female, while dam age had a greater influence overall. Productivity as a measure of total pounds of calf weaned through 5 yrs indicated that cows from dams that were 8-yr old or older weaned more total pounds of calf than cows from 3- yr old dams. Results indicated that heifers classified as low intake heifers, had greater mature BW at breeding and greater BCS than cows that were classified as average or high intake as heifers. However, DMI expressed as g/kg of BW displayed no differences with respect to cow age. Milk production was influenced by post-weaning intake for 2 and 5-yr old cows. The dam age study, indicated that dam age will affect future outcomes of replacement heifers. Cow BW at weaning displayed significance for dam age with cows born from 5- and 8-yr old and older dams having greater BW than cows born from 2-yr old. Cow yearling weight was significant for dam age with cows from 5-, 6/7-, and 8-years and older dams having greater yearling weights than cows from 2- and 3-yr old dams. The probability of remaining in the herd at 5-yr old varied across dam age groups with cows from 2-yr old and 5-yr old dams having greater probability to remain in the herd than the other age groups. Therefore, our research suggests that selection of replacement heifers based on post-weaning voluntary feed intake at 45 d post-weaning is not a strong indicator of lifetime productivity. Instead, cow age has a greater impact on lifetime productivity than heifer post-weaning voluntary feed intake.Item The influence of heifer post-weaning residual feed intake on subsequent production, reproduction, grazing behavior, supplement intake behavior, dry matter intake and milk production of Black Angus beef cattle(Montana State University - Bozeman, College of Agriculture, 2021) Parsons, Cory Todd; Chairperson, Graduate Committee: Timothy DelCurto; Julia Dafoe, Samuel Wyffels, Tim DelCurto, Darrin Boss and Megan Van Emon were co-authors of the article, 'Impacts of heifer post-weaning residual feed intake classification on reproductive and performance measurements of first, second and third parity Angus beef' in the journal 'Translational animal science' which is contained within this dissertation.; Julia Dafoe was a co-author of the article, 'The influence of residual feed intake and cow age on body weight and body condition change, supplement intake, resource use, and grazing behavior of beef cattle winter grazing mixed-grass rangelands' in the journal 'Animals' which is contained within this dissertation.; Julia Dafoe, Samuel Wyffels, Tim DelCurto and Darrin Boss were co-authors of the article, 'The influence of residual feed intake and cow age on dry matter intake post-weaning and peak lactation of Black Angus cows' in the journal 'Animals' which is contained within this dissertation.Residual feed intake (RFI) is a recognized measure of biological efficiency in beef cattle. However, RFI determination is expensive, time consuming and not well studied in beef cattle fed forage-based diets, nor how post-weaning RFI influences grazing behavior, supplement intake behavior or dry matter intake at different ages and physiological stages of production. Thus, the objectives of this research were to investigate how post-weaning RFI influences reproductive and productive performance, grazing behavior, supplement intake behavior as well as dry matter intake at different ages and physiological stages of production. A commercial herd of black Angus cows were utilized to conduct three experimental studies. Results indicate that classification of RFI for replacement heifers had little to no effect on subsequent beef cattle production and reproductive efficiency through the weaning of the 3rd calf. Subtle differences were denoted for cow Julian birth dates based on RFI classification and conception of 1st calf-heifers categorized as low RFI. However, heifer post-weaning RFI had little effect on subsequent cow performance (BW or BCS), grazing behavior, supplement intake behavior, and resource use. In addition, cow age significantly influenced cow performance, grazing behavior, supplement intake behavior, and resource use. We also observed high individual variability in grazing site selection, suggesting that individual-level factors may be driving grazing resource use and grazing behavior. Heifer post-weaning RFI did not influence mature cow dry matter intake, and this was consistent for both lactating and non-lactating beef cows. In contrast, cow age did correspond to quadratic increases of DMI and intake rates of mature cows. However, when DMI was expressed as g x kg body weight-1 no differences were observed with respect to cow age in lactating and non-lactating cows. Milk production was influenced by heifer post-weaning RFI for 2/3 and 5/6-yr old cows. Therefore, our studies suggests that selection for low RFI females would not impact overall herd productivity of cattle on foraged-based production systems, and that cow age has more of an impact on resource use, supplement intake, and grazing behavior, as well as DMI than heifer post-weaning RFI while grazing dormant-season mixed-grass prairie rangelands.Item Does calcium propionate elicit similar growth and reproductive responses as monensin in developing heifers?(Montana State University - Bozeman, College of Agriculture, 2017) Hubbard, Ashton Rose; Chairperson, Graduate Committee: Rachel L. Endecott; C. C. Reichhardt, A. R. Williams, I. R. McGregor, C. M. Page, D. M. Staudenmeyer and R. L. Endecott were co-authors of the article, 'Does calcium propionate elicit similar feed efficiency and reproductive responses as monensin in developing heifers?' submitted to the journal 'Journal of animal science' which is contained within this thesis.Replacement beef heifer development is critical for the continued production of beef and for ranch success. Objectives of this research were to investigate the growth and reproductive responses of developing heifers fed similar basal diets supplemented with pellets containing different feed additives. Pellet treatments consisted of 2.27 kg x heifer -1 x d -1 of: 1) control with no feed-additive (CON), 2) 200 mg x heifer -1 x d -1 monensin (MON), or 3) 40 g x heifer -1 x d -1 calcium propionate (PRO). Experiment 1 utilized one hundred and ninety-eight heifers (254 + or = 3.8 kg) stratified by BW and randomly assigned to one of six pens (n = 2 pens per treatment). Experiment 2 utilized fifty-eight heifers (304 + or = 3.4 kg) stratified by BW and randomly assigned to one of 12 pens (4 pens per treatment). Heifers were fed a grass hay basal diet in both experiments (Exp. 1: 65% TDN and 11% CP; Exp. 2: 62% TDN and 15% CP, DM basis). Experiment 1 was 129 d and Experiment 2 was 122 d. Body weights were collected at the beginning and end of each experiment, with interim BW collected every 30 d. Serum samples were collected via coccygeal venipuncture and analyzed for progesterone to determine pubertal status. Overall pregnancy rates and pregnancy rate from AI were determined. Experiment 1 observed no differences for initial BW, final BW, overall ADG, pregnancy rate from AI, or overall pregnancy rate (P > or = 0.16). Fewer CON and PRO heifers were pubertal at experiment start than MON heifers (P < or = 0.01) in Experiment 1, which was unexpected. Differences in puberty achievement were diminished at the end of the experiment. Experiment 2 observed no differences for initial BW, final BW, overall ADG, pregnancy rate from AI, or overall pregnancy rate (P > or = 0.19). Treatment had no effect on puberty achievement at beginning or end of experiment (P > or = 0.09). A period effect was observed for ADG in both experiments (P < or = 0.01) which may be related to cold stress. Neither calcium propionate nor monensin resulted in improved performance compared to no feed additive. Further research is warranted to elucidate the impact of calcium propionate on heifer development.Item A metabolomics approach for the study of long-term progesterone in domestic sheep and physiological processes in domestic and bighorn sheep(Montana State University - Bozeman, College of Agriculture, 2017) Herrygers, Melissa Rashelle; Chairperson, Graduate Committee: James G. Berardinelli; J. M. Thomson, K. A. Perz, K. B. Herrygers and J. G. Berardinelli were co-authors of the article, 'Effect of long-term progesterone on feed efficiency, body compostition, non-esterified fatty acids, and metabolic hormones in mature Rambouillet ewes' submitted to the journal 'Journal of animal science' which is contained within this thesis.; J. M. Thomson, K. A. Perz, K. B. Herrygers, V. Copie, B. Tripet, and J. G. Berardinelli were co-authors of the article, 'Using nuclear magnetic resonance spectroscopy (NMR) metabolic profiling to study the effect of long-term progesterone on metabolic profiles in Rambouillet ewes' submitted to the journal 'Journal of metabolomics' which is contained within this thesis.; J. White, C. Butler, R.A. Garrott, V. Copie, B. Tripet, and J. G. Berardinelli were co-authors of the article, 'Potential identification of metabolic biomarkers using nuclear magnetic resonance spectroscopy (NMR) metabolic profiling for nutrition status, season, and location of bighorn sheep (Ovis canadensis) in Montana and Wyoming' submitted to the journal 'Journal of metabolomics' which is contained within this thesis.Metabolomics allows for a snapshot of global metabolisms by studying metabolic intermediates and products of cellular metabolism. Experiments 1 and 2's objectives were to evaluate the effects of long-term P4 treatment, independent of the influence of the placenta and fetus, on changes in feed efficiency, BW, body composition, NEFA, metabolic hormones, and metabolites identified through nuclear magnetic resonance (NMR) metabolic profiling in mature Rambouillet ewes. Thirty, multiparous, 5- and 6-yr-old Rambouillet ewes were stratified by age and metabolic BW and assigned randomly to receive long-term P4 administration using controlled intravaginal releasing devices (CIDR) or no P4 (CIDRX; CIDR backbone only). Sera samples and body weights were collected every 14-d, along with CIDR/CIDRX replacement. Sera samples were assayed for metabolic hormones, NEFA, and metabolites. There were no differences in BW, RFI, STDMI, body composition, or temporal patterns of T3, T4, NEFA, or metabolites between CIDR- and CIDRX-treated ewes. Insulin concentrations were greater in CIDR-treated ewes than in CIDRX-treated ewes. Long-term P4 did not affect metabolism or body composition, independent from the presence of a fetus or placenta. Progesterone may increase tissue sensitivity to INS. In Experiment 3, the primary aim was to determine if NMR metabolic profiling has the potential to serve as a management tool for evaluating herds of bighorn (Ovis canadensis) sheep. Bighorn sheep herds were sampled between December of 2014 to March of 2015 in Montana and Wyoming. The sampling included 240 bighorn sheep ewes from 13 herds from geographically distinct locations at different times of the year. Metabolites identified by NMR in bighorn sheep serum were analyzed by pathway enrichment analyses, PLS-DAs, and biomarker analyses to determine if bighorn sheep herds can be distinguished by pregnancy status, geographic location, or time of year. NMR metabolic profiling could not distinguish between pregnant and non-pregnant bighorn sheep. Metabolic profiling did differentiate bighorn sheep herds and identified a subset of potential biomarkers that discriminated distinct geographic locations and time of year. Thus, NMR metabolic profiling has the potential to develop a suite of metabolites that wildlife managers can use to assess bighorn sheep nutrition and overall health.Item Effect of supplemental trace mineral level and form on peripubertal bulls(Montana State University - Bozeman, College of Agriculture, 2003) Alexander, Whisper Lynn; Chairperson, Graduate Committee: Raymond P. Ansotegui.Item The influence of biostimulation on the occurrence of puberty in beef heifers(Montana State University - Bozeman, College of Agriculture, 1985) Roberson, Mark StephenItem Dispersal by enzymatic digestion and recovery of bovine oocytes from whole ovaries(Montana State University - Bozeman, College of Agriculture, 1976) Strickland, James DaileyItem Urinary excretion of estrogenic substances by the bovine in the estrous cycle(Montana State University - Bozeman, College of Agriculture, 1957) Bergman, Robert KayeItem Postpartum interval to estrus and patterns of luteinizing hormone (LH) concentrations in first-calf suckled beef cows exposed to mature bulls(Montana State University - Bozeman, College of Agriculture, 1988) Custer, Edward Earl