Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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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 Supplement intake behavior of heifers grazing late summer dryland pasture(Montana State University - Bozeman, College of Agriculture, 2022) McClain, Tyrell Phillip; Chairperson, Graduate Committee: Timothy DelCurto; This is a manuscript style paper that includes co-authored chapters.Two studies were conducted to evaluate supplement intake and intake behavior of Rumax BoviBox protein supplements. For both studies, individual supplement intake, time spent at the feeder, and frequency of visits was measured using a SmartFeed Pro self-feeder system. In study 1, we examined the effects of free choice loose mineral salt on protein block supplement intake behavior of first-calf heifers. Heifers were stratified by weight, and, within stratum, randomly allotted to one of two supplementation treatments: 1) free-choice access to protein block supplement (30% CP) with access to loose mineral and salt; and 2) free-choice access to protein block supplement (30% CP) with no access to loose mineral and salt for a 42-day performance study. Individual animal was considered the experimental unit. No differences were observed for total supplement intake or supplement intake expressed as grams per kg body weight (BW; P > 0.05). In summary, availability of loose mineral salt did not have an impact on protein block supplement intake. In study 2, we evaluated Rumax BoviBox versus Rumax BoviBox HM protein supplements on supplement intake, intake behavior, body weight (BW), and body condition score (BCS) change of yearling heifers grazing dryland pastures during late summer. Heifers (428 kg) were stratified by BW and within stratum randomly assigned to one of two supplementation treatments: 1) free-choice access to Rumax BoviBox protein block supplement (30% CP, 23% salt; n = 29); and 2) free-choice access to Rumax BoviBox HM high magnesium protein block supplement (28.7% CP, 23% salt; n = 30). Supplement intake rate (g x min -1) displayed a treatment effect (P < 0.01) indicating that heifers in the Rumax BoviBox treatment had lower intake rate compared to Rumax BoviBox HM supplemented heifers. In conclusion, there were only minor differences in intake behavior and animal performance observed in both trials.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 The influence of biostimulation on the occurrence of puberty in beef heifers(Montana State University - Bozeman, College of Agriculture, 1985) Roberson, Mark StephenItem Fertility of non-puberal estrus, pregnancy rates and progesterone concentrations of beef heifers bred at puberal or third estrus(Montana State University - Bozeman, College of Agriculture, 1987) Byerley, Darryl JayItem Effects of crude ergot upon feedlot performance and upon certain blood components of beef heifers(Montana State University - Bozeman, College of Agriculture, 1972) Skarland, Andrew SelmerItem The effects of ruminally undegradable protein, propionic acid and monensin on puberty and reproductive efficiency in beef heifers(Montana State University - Bozeman, College of Agriculture, 1991) Lalman, David LeonItem Influence of form of supplementary copper and zinc on mineral status and performance of beef heifers during and after mineral antagonism(Montana State University - Bozeman, College of Agriculture, 1999) Bailey, John DenverItem The effects of degradable and metabolizable protein supply on the performance of first-calf heifers(Montana State University - Bozeman, College of Agriculture, 1998) Anderson, Leif Paul