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- ItemOpen AccessGenetic relationships between sex-specific traits in a crossbred beef cattle population(Colorado State University. Libraries, 1993) Speer, Nevil, C., author; Brinks, James S., advisorData used were obtained from the Fort Keogh Livestock and Range Research Laboratory (LARRL), Miles City, Montana. Data were from a crossbreeding experiment involving Hereford, Angus and Charolais cattle collected from 1962 to 1977. Traits studied and considered separate with respect to sex, included male and female birth weight (BWM and BWF), weaning weight (WWM and WWF), and postweaning average daily gain (ADGM and ADGF). Other traits studied were average adjusted mature weight (MW) of cows and fat thickness (FT), ribeye area (REA), yield grade (YG), quality grade (QG) and days on feed (DOF) of bulls and steers slaughtered at a weight constant endpoint of 1000 - 1050 lb. Multi-trait sire-maternal grandsire REML analyses were performed on straightbred and crossbred Hereford, Angus, and Charolais cattle. Observations on 2888 animals contributed to development of the A-inverse which represented relationships among 138 sires and maternal grandsires. Models for BWM, BWF, WWM, WWF, ADGM, ADGF, and MW analyses models included birth year, age of dam (2, 3, 4, 5+) and linear regression on weaning age. The DOF analysis model included birth year, age of dam, sex of calf (bull vs steer), age of dam-sex of calf interaction and linear regression on weaning age. Carcass trait (FT, REA, YG, QG) models included birth year, age of dam, sex of calf, age of dam-sex of calf interaction and linear regression on carcass weight. Linear regressions on individual breed percentage, combined reciprocal cross percentage (individual heterosis), dam breed percentage and dam combined reciprocal cross percentage (maternal heterosis) were also included in all models for analyses of all traits of interest. Correlations between direct components of birth weight, weaning weight, and postweaning average daily gain considered separately between male and female calves were .93, .90 and .74 respectively. The correlation between direct components of MW and DOF was -.66. Correlations between direct components of MW and carcass traits were -.54, -.18, -.18, and .41 for FT, REA, YG and QG, respectively. Correlations between maternal components of birth weight, weaning weight, and postweaning average daily gain considered separately between male and female calves were .86, .98 and .42, respectively. The correlation between maternal components of MW and DOF was -.71. Correlations between maternal components of MW and carcass traits were .40, .10, .08, and -.06 for FT, REA, YG and QG, respectively. Correlations between mat-dir and dir-mat of the same traits studied were moderate and ranged from -.44 to .47. Predictions of correlated responses in mature weight per standard deviation of direct response in male carcass traits were -32 lb, -13 lb, -10 lb, and 31 lb respectively for FT, REA, YG and QG. Correlated response predictions indicate selection for improved carcass cutability on a weight constant basis (increased leanness and decreased yield grades) would increase mature weight while selection for increased ribeye area and decreased quality grade scores (favorable) on a weight constant basis would result in decreased mature weights of females. Strong selection pressure for leanness may be antagonistic to commercial beef producers since results suggest sires selected on the basis of reducing fat in steer progeny also produce females that are larger at maturity when cattle are slaughtered at a constant weight endpoint. It should be noted, however, relationships between carcass traits and mature weight may differ when cattle are slaughtered at a constant age endpoint.
- ItemOpen AccessProcesses to improve storage shelf-life and palatability of beef(Colorado State University. Libraries, 2023) González Sánchez, Sara Victoria, author; Nair, Mahesh N., advisor; Geornaras, Ifigenia, advisor; Morgan, J. Brad, committee member; Gutierrez-Rodriguez, Eduardo, committee memberThree studies were conducted to evaluate processes to improve the storage shelf-life and palatability of beef. The first two studies evaluated the effects on retail shelf-life and palatability characteristics of beef following Suspended Fresh® storage. Suspended Fresh® (SF) is a patented, proprietary, trademarked process that allows the storage of beef muscles at temperatures at or slightly above their freezing point to slow down microbiological spoilage while maintaining the product's fresh status. These studies evaluated the impact of 60, 75, or 90 d of storage in SF (-2.7±0.3°C) on the retail shelf-life and palatability characteristics of steaks derived from inside rounds (IR), bone-in ribeyes (RE), and striploins (SL) from 10 (n=10) upper two-thirds Choice beef carcasses. Two steaks fabricated from each subprimal were vacuum-packaged, wet-aged for 21 d (3°C), and frozen (-20°C) for Warner-Bratzler shear force (WBSF) and sensory analyses. These steaks served as the control with regard to storage condition and time. The remainder of each subprimal was fabricated into three portions, and after vacuum packaging, were randomly allocated to an SF storage time of 60, 75, or 90 d. After each storage time, five steaks were fabricated from the subprimal pieces, overwrapped, and placed in a retail display case (3°C) under continuous fluorescent light for 7 d. Another two steaks were vacuum-packaged and stored at -20°C until WBSF and consumer sensory evaluations. Consumers (N=238) evaluated each sample for juiciness, tenderness, flavor liking, and overall liking. Instrumental and trained visual color were evaluated daily during retail display, and aerobic bacterial populations (APC), lactic acid bacteria, and Pseudomonas spp. were enumerated on days 0, 2, 4, and 7. Data were analyzed in R using a factorial design for the microbial counts or a split-plot for the rest of the analyses. Least-squares means were separated using a significance level of α=0.05. For all cuts, initial redness (a* values) of SF60 steaks were lower (P < 0.05) than SF75 and SF90 steaks. In general, irrespective of SF storage time or retail display day, trained panelists did not detect differences in lean color and discoloration of steaks. For all cuts, the APC of SF60 steaks on days 0, 2, and 4 of retail display were lower (P < 0.05) than those of SF75 and SF90 samples. The WBSF values decreased (P < 0.05) with increased storage time for all the cuts. Similarly, the consumer tenderness rating scores of IR and SL generally increased with the SF storage time. However, storage time did not influence (P ≥ 0.05) the juiciness, flavor, and overall liking of any cuts. The results of this study suggest it would be feasible to extend the storage time of beef while preserving or improving the sensory quality when held at optimal conditions above the freezing temperature. The third study was conducted to evaluate the effects of different temperature and time treatment combinations (1A: 56.1°C and 71 min; 1B: 56.1°C and 150 min; 1C: 56.1°C and 240 min; 2A: 61.7°C and 8 min; 2B: 61.7°C and 150 min; 2C: 61.7°C and 240 min) of sous vide cooking on the palatability of beef biceps femoris. Beef biceps femoris were sliced into 1.6-cm steaks, vacuum packaged as 4.5 kg bags, and randomly assigned to one of the six treatments with 16 packages (n=16) per treatment. Cooked and chilled packages were weighed, and then the weight of the meat was taken to measure cooking loss. Weighed samples were divided into two halves: one was left non-marinated, and the other was assigned to marination. Two 1.6-cm non-marinated steaks were randomly selected and cut in half to measure the internal cooked color. Additionally, non-marinated and marinated steaks were randomly selected for WBSF and sensory analysis by a trained panel. Data were analyzed using a complete randomized design in R with a significance level of α=0.05. The cooking loss of samples increased as the temperature and dwell time combinations increased (P < 0.05). Internal redness of steaks decreased (P < 0.05) with increased temperature and dwell time. The only major difference in WBSF and the trained sensory panel results was between treatment 1C (56.1°C and 240 min) and 2A (61.7°C and 8 min), where 1C samples had lower WBSF values and higher perceived tenderness scores than 2A samples. These results suggest that biceps femoris samples can be cooked at conditions examined in this study with minimal impact on palatability, allowing producers more flexibility with cooking time to optimize production time and energy while reducing cooking loss. Overall, the findings of these studies should be useful to the beef industry as they consider strategies for improving the storage shelf-life and palatability of beef.
- ItemOpen AccessTemperament and maternal behavior of beef cattle(Colorado State University. Libraries, 2023) Rogers, Corley, author; Grandin, Temple, advisor; Engle, Terry, committee member; Archibeque, Shawn, committee member; Garry, Frank, committee memberThis thesis contains both a literature review and an observational study about temperament and maternal behavior of beef cattle. The literature review covers maternal behavior, maternal protectiveness, temperament, and stress in beef cows. The aim of the experiment was to compare the distance maternal protective behaviors were performed against measurements of temperament. The results of the study showed very little correlation between how the cow defends her calf and her behavior in the chute. The overall aim of this thesis was to was to address the paucity of data regarding how maternal protectiveness and temperament are related and if there is an inadvertent increase in the potential for predation if breeding for a docile temperament.
- ItemOpen AccessLife cycle environmental impacts of utilizing hemp seed meal as a protein source in sheep feedlot rations(Colorado State University. Libraries, 2023) Clark, Samantha Maye, author; Dillon, Jasmine, advisor; Archibeque, Shawn, committee member; Nachappa, Punya, committee member; DiVerdi, Joseph, committee memberHemp seed meal is a protein-rich byproduct of the hemp industry, obtained from the cold press extraction process used to produce hemp oil. The objective of this work was to evaluate the environmental impact of using hemp seed meal as a protein supplement in sheep production. A cradle-to-gate life cycle assessment (LCA) was conducted on three sheep production systems which differed in the feedlot phase: one fed a feedlot ration containing soybean meal as the protein source (soybean meal diet), one fed hemp seed meal in the feedlot ration (hemp diet), and one fed organic hemp seed meal in the feedlot ration (organic hemp diet). Animal performance data were collected from a nutrition trial. Hemp production, harvest, and processing data were provided by a hemp product company. Economic and physical allocation were applied to the hemp diet systems, and the ReCiPe Midpoint (H) methodology was used to calculate the global warming (i.e., carbon footprint), water consumption, land use, and fossil resource scarcity impacts on a per kg lamb live weight basis for each system. Carbon footprint ranged from 10.1 to 11.4 kg CO2eq/kg LW, water consumption ranged from 1.3 to 4.2 m3/kg LW, fossil resource scarcity ranged from 0.5 to 0.8 kg oil eq/kg LW, and land use ranged from 2.8 to 6 m2a crop eq/kg LW. Impact assessment results were not sensitive to a 10 or 20% increase in electricity demand at processing. The use of IPCC Tier 2 methods for estimating enteric methane emissions from sheep resulted in a 7.5–8.5% increase in the carbon footprint, relative to a mechanistic equation present in the Ruminant Nutrition System model. Physical allocation resulted in greater impacts of the hemp diet systems than the soybean diet systems for all categories except land use. However, economic allocation resulted in greater impacts for the soybean diet systems than the hemp diet systems for all categories evaluated. This was explained by inherent differences between the allocation method, as physical allocation attributed 80% of the environmental burden to hemp seed meal, while economic allocation attributed 0% of the environmental burden to hemp seed meal due to the current lack of an economic value for hemp seed meal. The production volume of dependent products ("dependent products", or products for which a change in demand does not affect production volume, commonly referred to as co- or byproducts) are driven by monetary value of the determining product (the product for which a change in demand affects the production volume), but relationships between co-products change overtime. Therefore, as the hemp industry continues to develop, an economic value may be placed on hemp seed meal with implications for its relative ability to reduce the environmental impacts of livestock production. As agricultural industries strive to become more environmentally efficient, they must be adaptive to changes in both monetary value and environmental impact, which are intrinsically related. This research demonstrated the importance of allocation choice in assessing the impact of feeding byproducts on the environmental impact of livestock production systems. Economic allocation better reflected the monetary driving factor for hemp production than physical allocation. As such, the inclusion of hemp seed meal in a feedlot ration reduced the environmental impact of sheep production systems.
- ItemOpen AccessAn integral approach for management challenges in the dairy industry(Colorado State University. Libraries, 2023) Herrera, Natalia, author; Pinedo, Pablo, advisor; Velez, Juan Santiago, committee member; Holt, Timothy, committee memberA growing body of literature recognizes the importance of including an integrated approach to animal welfare and employee well-being in the dairy industry. The current thesis aims to describe this integral approach by presenting two research projects developed in a commercial dairy under the same management. Hence, an animal welfare pilot study was performed on a dairy farm located in northern Colorado, and an employee well-being study was developed on three dairy farms, two located in northern Colorado and one in northern Texas. Both projects were performed during the year 2022 and the dairies are administrated by the same management. The overall structure of this thesis takes the form of three chapters, including each perspective previously analyzed in the current management challenges explored in the dairy industry. Chapter one presents an extensive literature review of both approaches identified as management challenges in the dairy industry. Then, chapter two analyses the results of an online survey undertaken from September through November 2022 that aimed to explore employee adaptation, perception, and understanding of technology in the dairy farm. In order to accomplish the goal of this pilot study, the online survey completed by two-hundred-sixty-six employees was analyzed and the results are presented in chapter two. Chapter three presents the results of an observational study done on cow-calf behavior from the expulsion of the calf up to the separation in a dairy system located in northern Colorado. One-hundred-sixty-seven calving that occurred from May to June were analyzed and the results are presented in chapter three. Results are briefly described next. First, from the adaptation, perception, and understanding of technology in the dairy farm study, employees recognize and have positive feelings towards the technology implemented at work, where they highlighted the understanding of its benefits, and recognized the technology as a tool that helps them to be more efficient. However, the challenges to adapting to new technology were mainly determined to be personal limitations, such as not knowing the language of the technology and impairments to seeing. Also environmental limitations were recognized by the employees such as cold weather, wind, or an environment that is too dark or too bright. Lastly, the level of perception of technology was found to be associated with the level of education and level of English of the employee, but no significant differences were identified by age or gender. Findings are promising and the current thesis invites the academia to extended this type of research in other livestock operations that adopt precision livestock farming technology. Second, from the cow-calf behavior from the expulsion of the calf up to separation in a dairy system research, with an average time of 2,489 seconds together, the predominant behavior found by the dam was the intensive licking towards their calf, and secondary particular behaviors were lying down after calving, aggressive behavior upon a surrogate cow, and a following behavior upon separation. On the calf side, the main behaviors were licking the cow, and mobilizing with their two front hooves. Less common behaviors were standing up, reaching the udder, suckling, and looking at her cow upon separation. Moreover, animal-level variables that were associated with these behaviors were found to be parity and calving difficulty. Also, for environmental-level variables, the drop time, calving in the patio, and temperature were associated with these behaviors as well. In general, no significant associations were found for twins, calf gender, and heat index. Lastly, when the future health performance of both animals was analyzed, only the stand-up behavior of the calf was significantly associated with an increased average daily gain weight from birth to weaning, compared to calves that did not stand up. The novel findings presented in this thesis will help dairy management to better understand latent challenges in the industry with an integral approach that includes animal welfare and employee well-being. This study extends the knowledge of cow-calf contact systems by exploring the animal behavior right after calving and up to separation and provides a comprehensive assessment of adaptation, perception, and understanding of precision livestock farming technologies by the dairy employee. The conclusions from this thesis will add to the rapidly expanding field of integrating animal and employee health into integral strategies for current management challenges in the dairy industry.