Browsing by Author "Holt, Timothy, committee member"
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Item Open Access An 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.Item Open Access Epidemiological, physiological and genetic risk factors associated with congestive heart failure and mean pulmonary arterial pressure in cattle(Colorado State University. Libraries, 2014) Neary, Joseph Michael, author; Garry, Franklyn, advisor; Thomas, Milton, advisor; Orton, Christopher, committee member; Enns, Mark, committee member; Morley, Paul, committee member; Holt, Timothy, committee memberCongestive heart failure, secondary to pulmonary hypertension, has historically been considered a disease associated with high altitude exposure. The disease was first reported to occur at altitudes over 2,440 m (8,000 ft.) and so became known as "high altitude disease". One common clinical sign due to congestive heart failure in cattle is swelling of the brisket. Consequently, the disease also became known as "brisket disease". In more recent years, congestive heart failure has been reported to occur in both beef and dairy cattle at a more moderate altitude of 1,600 m. Anecdotal reports from cattle producers in Nebraska, Colorado and Texas suggest that the incidence of congestive heart failure may be increasing. This suggests that bovine congestive heart failure is not strictly a disease of high altitude exposure. Anatomical studies of cattle indicate that cattle have a smaller lung volume and alveolar surface area available for gas exchange than mammals with similar body masses and oxygen requirements. This may be because selection for increased growth rate, and other traits of high production, increases metabolic oxygen demand. The overarching hypothesis of this doctoral dissertation was that congestive heart failure secondary to pulmonary hypertension is not strictly a disease of high altitude but, a multifactorial disease, that is also associated with physiological traits that increase metabolic oxygen demand relative to oxygen supply via the cardiopulmonary system. The goal of this doctoral dissertation was to identify epidemiological, physiological and genetic risk factors associated with congestive heart failure and increased mean pulmonary arterial pressure in cattle. The results of this dissertation indicate that pulmonary arterial pressures of cattle are substantially higher than other mammalian species. Among pre-weaned calves, mean pulmonary arterial pressures increased significantly with age even at the moderate altitude of 1,470 m. As hypothesized, high oxygen demand relative to supply was positively associated with mean pulmonary arterial pressure in both pre-weaned calves at high altitude (2,170 m) and feedlot cattle at moderate altitudes (1,300 m). A study of 10 Canadian feedlots indicated that the risk of congestive heart failure increased from the year 2000 to the year 2012. The risk of congestive heart failure increased more than the underlying change in the risk of digestive disorders. Death from congestive heart failure occurred throughout the feeding period but typically occurred late in the feeding period, which makes this disease particularly costly to the feedlot industry. Treatment for respiratory disease was a significant risk factor for CHF. Increased growth rate and increased feed efficiency were risk factors for increased mean pulmonary arterial pressure in cattle. Mean pulmonary arterial pressures were significantly higher at the end of the confined feeding period at moderate altitude (1,300 m) than in pre-weaned calves at high altitude (2,170 m). Growth promotion through a steroid implant containing estradiol and trenbolone acetate did not significantly increase mean pulmonary arterial pressure as hypothesized. However, diastolic pulmonary arterial pressure was significantly lower than non-implanted controls, which suggests that one or both of these steroid hormones has cardio-pulmonary protective effects. Genome-wide association analyses of mean pulmonary arterial pressure and traits physiologically associated with mean pulmonary arterial pressures among calves at 4 and 6 months of age did not identify any concordant single nucleotide polymorphisms (SNPs). However, multiple SNPs were identified to be associated with mean and systolic pulmonary arterial pressures that have been associated with pulmonary hypertension in humans or have a plausible biological role in the development of pulmonary hypertension. In conclusion, the results of these investigations provide evidence to suggest that congestive heart failure of cattle is a multifactorial disease that is exacerbated by high altitude exposure.Item Open Access Estimation of heterotic effects on stayability in beef cattle(Colorado State University. Libraries, 2019) Huff, Emma, author; Enns, R. Mark, advisor; Speidel, Scott, committee member; Holt, Timothy, committee memberStayability in beef cattle is defined as the probability that a cow remains in the herd until age six given that she has calved as a heifer. In some breeds with total herd reporting, those cows are required to calve every year. Stayability influences herd profitability by decreasing the need for replacements by increasing the number of cows that reach the typical breakeven age of six. Stayability is a binary trait on the observed scale and is considered a lowly heritable trait. General consensus is that lowly heritable traits should be subject to higher levels of heterosis in crossbreeding programs. Therefore, heterosis should have a positive effect on the cows' ability to remain in the herd until age six. The objective was to estimate maternal and individual heterosis values for stayability. Data was obtained from the American Gelbvieh Association and included a total of 13,114 animals, with 5 being purebred American Angus and 5,493 purebred Gelbvieh, and the rest being a combination of crossbred animals. Variance components and fixed heterosis effects were estimated from single trait animal models using a probit threshold link function. The model included contemporary group as a fixed effect and breed percentage as a linear covariate. Two models were evaluated with different heterosis covariates, model one included only individual heterosis and model two included individual and maternal heterosis. Heterosis was estimated to be 48.96% when individual heterosis is 100% with the first model. For the second model 100% individual heterosis was estimated to be 48.88% and 49.57% was the estimate for 100% maternal heterosis. The results from this experiment indicate that stayability is affected by heterosis and that these effects should be accounted for in cattle evaluation using pure and crossbred data.Item Open Access Evaluating the genetic architecture of the Japanese Wagyu breed within the United States(Colorado State University. Libraries, 2022) Heffernan, Kathryn, author; Speidel, Scott E., advisor; Thomas, Milt, committee member; Enns, Mark, committee member; Blackburn, Harvey, committee member; Holt, Timothy, committee memberThe objective of this thesis is to better understand the genetic architecture of Japanese Wagyu cattle in the United States to improve on current breeding strategies, as well as help to develop new strategies to increase the genetic diversity of the U.S. Wagyu population. For this study, pedigree data (n = 48) were collected on full-blood Japanese Wagyu sires and dams, and high-density genotype data (n = 414) were collected on Japanese Wagyu, Ayrshire, Brahman, Brangus, Devon, Holstein, Milking Devon, Milking Shorthorn, Shorthorn, Simmental, South Devon, Angus, Jersey Island, and Brown Swiss cattle. Inbreeding coefficients were calculated from the pedigree data and averaged 0.19, with a minimum coefficient of zero, max coefficient of 0.43, and a standard deviation of 0.08. Using the genotypes, a principal component analysis (PCA), an admixture graph, and a phylogenetic tree were computed to ascertain the population structure and breed composition of modern Japanese Wagyu cattle in relation to other breeds. The majority of the Japanese Wagyu had an elongated dispersal that overlapped with the origin of the PCA graph. Japanese Wagyu also averaged 85.5% indicine influence as indicated by the admixture graph, and the phylogenetic tree showed Japanese Wagyu as the closest branch to the root breed Brahman. These results suggest that Japanese Wagyu are an inbred population. While mostly Bos indicus, these results suggest that Japanese Wagyu are admixed with low percentages of Bos taurus breeds such as Simmental and Brown Swiss.Item Open Access Evaluation of pregnancy rates following timed AI in beef heifers after synchronization of follicular waves using a 14-d controlled internal drug release insert, and the lifetime productivity of beef heifers conceiving to, or sired by, AI(Colorado State University. Libraries, 2012) French, Jesse, author; Peel, Kraig, advisor; Holt, Timothy, committee member; Ahola, Jason, committee member; Whittier, Jack, committee memberThree studies were conducted to evaluate the efficacy of a timed AI (TAI) estrous synchronization protocol that used a 14-d controlled internal drug release (CIDR) insert and a GnRH injection on d 9 to force ovulation of potentially persistent follicles and induce a second wave of follicle growth. In the first study 710 yearling heifers across 4 locations were assigned to 1 of 3 treatments: 1) 14-d GnRH-9 heifers (n = 242) received CIDR (1.38 g progesterone) and 100 μg GnRH on d 0, 100 μg GnRH on d 9, and 50 mg PGF2α on d 14 concurrent with CIDR removal, 2) 14-d 6 h PG heifers (n = 233) were identical to 14-d GnRH-9 except that on d 14, 2 25 mg injections of PGF2α were given 6 h apart, and 3) 5-d CO-Synch + CIDR heifers (n = 235) received 100 μg GnRH and CIDR on d 9 and a single 25 mg PGF2α at CIDR removal. All 3 treatments received 100 μg GnRH with TAI at 72 ± 2 h after CIDR removal. The 14-d GnRH-9 TAI pregnancy rate (54.5%) did not differ (P = 0.57) from the 14-d 6h PG TAI pregnancy rate (53.6%). The TAI pregnancy rate of 14-d protocols combined was 54.1%, and was not different (P = 0.20) from the 5-d CO-Synch + CIDR TAI pregnancy rate of 46.4%. The following year 319 yearling heifers across 4 locations were assigned to 1 of 3 treatments: 1) 14-d GnRH-9 (n = 107; as described earlier), 2) 14-d PG (n = 107) was identical to 14-d GnRH-9 except instead of receiving GnRH on d 0 they received 25 mg of PGF2α and, 3) 5-d CO-Synch + CIDR (n = 104; as described earlier). All treatments received 100 μg GnRH at TAI 72 ± 2 h after CIDR removal. Heifers' ovaries (n = 120) were ultrasounded at 2 locations on d 0, 9, 14, and 17 of the estrous synchronization protocol to determine ovarian structures and response. The 14-d GnRH-9 TAI pregnancy rate (52.3%) was not different (P = 0.82) than 14-d PG (47.6%), nor was the TAI pregnancy rate of both 14-d treatments combined (50.0%) different (P = 0.66) from 5-d CO-Synch + CIDR (47.1%). Based on ultrasonography, the 14-d GnRH-9 treatment induced a second wave of follicular growth in 25.9% of heifers while 14-d PG heifers had larger (P = 0.01) follicle size on d 9 but did not reduce (P > 0.10) corpora lutea at TAI compared to 14-d GnRH-9 or 5-d CO-Synch + CIDR. That same year 453 heifers at another location were assigned to 1 of 3 treatments: 1) 14-d GnRH-9 (n = 150; as described earlier), 2) 14-d GnRH-7 (n = 150) received 100 μg GnRH and CIDR on d 0, 100 μg GnRH on d 7, 25 mg PGF2α on d 14 at CIDR removal, and 100 μg GnRH at TAI 63 ± 3 h after CIDR removal, and 3) 7-d CO-Synch + CIDR received 100 μg GnRH and CIDR on d 7, 25 mg PGF2α at CIDR removal, and 100 μg GnRH at TAI 63 ± 3 h after CIDR removal. Pregnancy rate to TAI of 14-d GnRH-9 (51.3%) was not different (P = 0.75) than 14-d GnRH-7 treatment (48.0%), nor was the TAI pregnancy rate of both 14-d treatments (49.6%) different (P = 0.83) from 7-d CO-Synch + CIDR (48.6%). These data indicate that the 14-d CIDR estrous synchronization protocol with d 9 GnRH produces comparable pregnancy rates to TAI compared to the industry utilized 5-d and 7-d CO-Synch + CIDR estrous synchronization protocols. However, the additional labor and pharmaceutical cost of handling heifers on d 9 raises the question whether it's a viable TAI estrous synchronization alternative. The final experiment evaluated the lifetime productivity of heifers conceiving to AI or natural service (NS), and heifers sired by AI vs. NS. Calving and breeding records (n = 6,693) at one location for 1,173 Angus females and were obtained from 1991 to 2010. Lifetime weight weaned, calves weaned, and revenue produced was determined and analyzed. Heifers that conceived to AI had greater (P < 0.0001) lifetime weight weaned, lifetime calves weaned, lifetime revenue, and greater (P < 0.05) average annual weaning weight than heifers that conceived to NS. There was no difference (P > 0.10) in average annual weaning weight, lifetime weight weaned, lifetime calves weaned, or lifetime revenue produced between heifers sired by AI or NS. Estrous synchronization and AI can be a valuable tool to produce replacement heifers that conceive earlier, and in doing so increase their lifetime productivity.Item Open Access Evaluation of roughage inclusion rate within a total mixed ration effects on feedlot performance, carcass characteristics, and fatty acid composition of subcutaneous adipose, intramuscular adipose, and muscle tissue of Wagyu cattle(Colorado State University. Libraries, 2015) Linton, Kathryn, author; Peel, Kraig, advisor; Archibeque, Shawn, committee member; Holt, Timothy, committee memberThe objective of this study was to investigate the effect of roughage inclusion rate of 10, 20, and 30% within a total mixed ration on feedlot performance, carcass composition and marbling distribution in Wagyu cattle (n=41). Upon arrival, cattle were acclimated to bunk style feeding. Initial body weights were collected. Animals were blocked by sex and weight to be assigned to 1 of 3 roughage inclusion rate treatments. Treatments included 1) 10% roughage inclusion on dry matter basis; 2) 20% roughage inclusion and 3) 30% roughage inclusion on dry matter basis. Diets were formulated to be isoenergentic, isonitrogenous, and isoamylolytic. Animals were weighed every 7d. For harvest animals were transported to a commercial abattoir. Hot carcass weight (HCW) was determined at time of harvest, intramuscular adipose, and subcutaneous adipose tissue was collected at harvest and snap frozen for analysis of FA composition. Longissimus muscle area (LMA) and backfat (BF) carcass measurements were determined after 21d storage at 0° C chill. A 1.25 cm cross section of longissimus dorsi at 12th and 13th rib interface was collected for Computer Vision System Ribeye Camera evaluation of marbling distribution. Limited treatment effects were observed. Feedlot performance and carcass characteristics were not significantly affected by roughage inclusion rate (P>0.05). Treatment presented a significant effect on Linoleic acid (C18:3) concentration within the longissimus muscle tissue (P=0.05). Concentration of C18:3 increased with increased roughage inclusion rate. Fatty acid profiles for LM, IMF and SQ tissues were similar across treatments. There was not treatment effect for marbling distribution collected via Computer Vision System Ribeye Camera evaluation. Overall, the data suggests that roughage inclusion rate causes very little impact on feedlot performance, carcass characteristics, fatty acid composition and marbling distribution in Wagyu cattle.Item Open Access Extracting copper from dairy footbaths to prevent heavy metal bioaccumulation in agricultural land(Colorado State University. Libraries, 2018) Jalali, Sam, author; Engle, Terry, advisor; Archibeque, Shawn, committee member; Holt, Timothy, committee member; Roman-Muniz, Noa, committee memberTo view the abstract, please see the full text of the document.Item Open Access Genetic relationship between ewe longevity and structural foot and leg traits in sheep(Colorado State University. Libraries, 2022) Yazar Gunes, Hilal, author; Enns, R. Mark, advisor; Speidel, Scott E., advisor; Thomas, Milton G., committee member; Holt, Timothy, committee memberTo view the abstract, please see the full text of the document.Item Open Access Heterosis and breed percentage effects on reproductive performance and preweaning traits in a multibreed beef cattle herd in Panama(Colorado State University. Libraries, 2023) Gonzalez Murray, Roderick Alexander, author; Speidel, Scott E., advisor; Enns, R. Mark, advisor; Thomas, Milton G., committee member; Coleman, Stephen J., committee member; Holt, Timothy, committee memberPanama is located in Central America and is characterized by a tropical climate. Given the tropical climate conditions, Zebu cattle (Bos indicus) are the most predominant breeds in cow–calf systems due to greater resistance to internal and external parasites, and greater tolerance to elevated ambient temperatures and humidity when compared to Bos taurus beef breeds. Zebu is a breed that is reproductively inefficient due to Age at First Calving (AFC) being over 36 months and having longer calving intervals (CI), ranging between 12.2 to 26.6 months. The Panamanian cow-calf system reports an average annual birth rate of 55%, with a range of 35% to 60%, depending on the province. This reduced efficiency reported in the cattle production system is also reflected in low kilograms of weaned calves per cow exposed to AI or Bull (80kg) to 120 WW/cow exposed), high age at first calving (over 36 months), long calving interval (more than 450 days), and perhaps low-income returns ranging between 8 to 15% per dollar invested. The reproductive efficiency of a herd is one of the main components of a cow-calf system economically. Other important traits that affect the system efficiency and profitability are the preweaning traits: birth weight (BW) and weaning weight (WW). The lack of system efficiency and profitability is why different breeds have been introduced to the country to be used in crossbreeding systems to obtain the benefits of heterosis in growth and reproductive traits. The beneficial effects of crossbreeding on animal performance have been well established, benefiting low heritability traits such as those related to reproduction. For that reason, in tropical environments, matching the optimum cow numbers with the correct genetic potential in the appropriate production environment can maximize economic benefits. In the tropics, reduced pre- and post-weaning growth and reproductive efficiency are the main limiting factors in the cow-calf system. Preweaning traits are a combination of the direct genetic, maternal genetic, maternal permanent environment, and temporary environmental effects. The challenge for farmers in Latin American countries is to identify those animals that achieve maximum productive performance in a given agro-ecological environment, and to maintain a balance between longevity and generation intervals, in order to obtain the greatest genetic gain per unit of time. Knowledge of the genetic effects of breeds and their crosses in various climatic and forage conditions can be used to identify optimal breed combinations and crossbreeding systems for existing markets. Based on the heterogeneity of herds in tropical regions due to the introduction of multiple breeds and the different crossbreeding systems utilized, it is necessary to carry out a multibreed evaluation that includes all crossbred and purebred individuals into a single analysis and accounting for the direct and maternal breed and heterosis effect evaluation. As we mentioned above, different breeds have been introduced in Panamá, but no genetic evaluation program has been developed in the country, to improve the efficiency of cow-calf production. However, it is important to evaluate the breed groups and heterosis effect through productivity indicators to know the relative performance of the breeds and crosses of Zebu and Bos taurus cattle in the cow–calf system. Therefore, the objectives of this study were to determine heterosis and breed percentage effects on reproductive performance and preweaning traits in a multibreed beef cattle herd in Panama. For this, traits like age at first calving (AFC), calving interval (CI), gestation length (GL), birth weight (BW), and weaning weight (WW) that constitute important elements of the breeding objective of beef cattle producers were selected as the traits to evaluate in this study. All the reproductive and preweaning data utilized in this investigation was produced by a multibreed cattle population of the Livestock Experimental Station of Panama Agricultural Innovation Institute (IDIAP) in Gualaca, province of Chiriqui, Republic of Panama. The herd was comprised of the following genetic groups and breed percentage combinations: tropical adapted Brahman (BR), Nellore (Ne), Undefine Bos indicus (BI), Guaymi Creole (CR), Senepol (SP) Romosinuano (RS); Bos taurus (BT), Simmental (SM), Angus (AN), Red Angus (AR), Limousin (LM), Charolais (CH), Wagyu (WA), and Others (OTH); crossbreeds (CX), Beefmaster (BF), Three CX (F1 x different BT), R1(Backcross BR), R2 (Backcross BT), Composite (combination of at least 4 different breeds with less than 25% of Zebu), Upgraded Brahman (87.5% BR 12.5% BT), B1 (62.5% Zebu + 37.5% BT), B2 (62.5% BT + 37.5% Zebu). In general, this dissertation was divided into three different studies according to the physiological status of the individual producing the phenotypic record (e.g., calf, heifer, and multiparous cows). The first study estimated the influence of heterosis and breed percentage on age at first calving (AFC). An animal model was utilized to estimate variance components using data from 619 cows and 1,142 individuals in the pedigree from the multibreed herd with data collected between 2000 to 2019. The average AFC was 42.7 ± 10.5 months, with an estimated regression coefficient for AFC on heterosis of -0.046 ± 0.009 month/percent of outcross. Lower AFC was observed for the F1, R2, and B2, with 39.8 months, 39.9 months, and 39.5 months, respectively. A reduction in AFC was also observed for the Beefmaster (-0.13 ± 0.05 months) and the OTHER category (-0.14 ± 0.04 months). A heritability of 0.17 0.10 was estimated for AFC. These results suggest that heterosis had a beneficial influence on AFC measurements in a multibreed beef cattle herd in Panama. The second study focused on estimating the influence of heterosis and breed percentage on calving interval (CI) and gestation length (GL), and the correlation between age at first calving (AFC) and CI. Calving performance data included 1,291 repeated observations of CI and GL from 502 cows with a 3-generation pedigree consisting of 2,840 individuals in the pedigree with data collected between 2000 to 2021. A repeated records animal model was utilized to estimate variance components for both CI and GL. Additionally, a bivariate animal model was used to estimate the genetic correlation between CI and AFC. The average CI was 572.6 ± 140 days, and for GL was 284.2 ± 6.3 days, for this population. The regression of CI and GL on heterosis was not significant. A lower CI was observed for the F1, and Three CX, translating to 558.7 days and 567.2 days, which represents 2.3% and 1.3% reduction in CI, respectively when compared to the Zebu group. Calving interval was estimated to be lowly heritable (0.037 ± 0.026), however, a positive genetic trend over the duration of the study. The analysis between CI and AFC revealed a moderate genetic correlation (0.49 ± 0.36) which allows the establishment of a selection program to improve AFC and CI, due to the pleiotropic effect, which would improve the fertility of this multibreed herd in Panama. Finally, the third study aimed to estimate the influence of heterosis and breed percentage on birth weight (BW) and weaning weight (WW). Data from 900 calves with 2,843 individuals in the pedigree was utilized in a bivariate animal model for BW and WW was utilized to estimate variance components. The estimated regression coefficient for BW on heterosis was not significant, however, for WW was 0.072 ± 0.027 kg/percent of outcross. Lower BW and WW were observed for the Japanese, and B1, while R2 and Upgrade had the highest average WW. Heritability for BW was found to be low 0.14 ± 0.06 and moderate for WW 0.26 ± 0.09. The proportion of variation of WW accounted by the maternal permanent environment for WW was 0.2 ± 0.09. The estimated genetic correlation between additive genetic BW and WW was 0.63 ± 0.30, while a negative, additive genetic correlation was observed for WW and WW maternal -0.43 ± 0.37. These results suggested that heterosis had a beneficial influence on WW but a limited effect on BW. Additionally, increasing the percentage of WA and BR negatively influenced WW measurements in this multibreed population.Item Open Access Influence of BOVAMINE DEFEND® Plus on growth performance, carcass characteristics, estimated dry matter digestibility, rumen fermentation characteristics, and immune function in finishing beef steers(Colorado State University. Libraries, 2024) Miller, Alexandra C., author; Engle, Terry E., advisor; Edwards-Callaway, Lily, committee member; Holt, Timothy, committee memberOne hundred and eighty crossbred beef steers (406.0 ± 2.2 kg) were used to determine the impact of a novel direct-fed microbial (DFM) on growth performance, carcass characteristics, rumen fermentation characteristics, and immune response in finishing beef cattle. Steers were blocked by body weight and randomly assigned, within block, to 1 of 2 treatments (3 replicates/treatment: 30 steers/replicate). Treatments included: 1) no DFM (control) and 2) DFM supplementation at 50 mg∙animal-1∙d-1 (BOVAMINE DEFEND® Plus). All steers were fed a high-concentrate finishing diet and individual feed intake was recorded daily via the GrowSafe® system. Body weights were collected every 28 d. On d 55, 10 steers per pen were injected with ovalbumin (OVA). Jugular blood samples were collected from each steer on d 0, 7, 14, and 21 post-injection. On d 112, the same steers were injected again with OVA and intramuscularly with a pig red blood cell solution. Jugular blood samples were collected from each steer on d 0, 7, 14, and 21 post-injection. On d 124 rumen fluid was collected from 3 steers per treatment and used to estimate in vitro rumen fermentation characteristics. Equal numbers of steers per treatment were transported to a commercial abattoir on d 145, 167, and 185 of the experiment, harvested, and carcass data collected. Initial body weight (BW) was similar across treatments. On d 28 and 55, steers receiving DFM had heavier BW (P < 0.01) compared to controls. Average daily gain was greater in DFM-supplemented steers from d 0 to 28 (P < 0.01) and d 0 to 55 (P < 0.01) of the experiment compared to controls. Overall dry matter intake was greater (P < 0.04) and overall feed efficiency was similar in DFM-supplemented steers compared to controls. Dressing percentage (P < 0.02) was greater in steers receiving DFM compared to controls. Antibody titers to injected antigens were similar across treatments. However, red blood cell superoxide dismutase activity was greater (P < 0.05) in DFM-supplemented steers compared to controls. In vitro molar proportions of isobutyric and butyric acid were greater (P < 0.01) and dry matter (DM) digestibility tended (P < 0.07) to be greater in rumen fluid obtained from steers supplemented with DFM. These data suggest that BOVAMINE DEFEND® Plus supplementation improves growth performance during the initial period of the finishing phase, increases overall dry matter intake and dressing percentage, and may impact antioxidant status in beef cattle.Item Open Access Pulmonary arterial pressure as an indicator for high altitude disease in cattle: breed differences and relationships with growth performance(Colorado State University. Libraries, 2015) Crawford, Natalie Faye, author; Enns, R. Mark, advisor; Thomas, Milton, advisor; Holt, Timothy, committee memberHigh altitude disease (HAD), commonly known as brisket disease, is a natural occurring phenomenon in cattle. This disease occurs most often in high altitude (> 1,500 m) environments, where adaptability to the hypoxic conditions may be insufficient. Pulmonary arterial pressure (PAP) scores are the most useful tool available to cattle producers in predicting an animal’s susceptibility to HAD. The all-encompassing objectives for this thesis were to delineate the important factors influencing PAP scores and understand the relationships between PAP scores and other performance traits, where selection for more favorable PAP may have adverse effects on those performance traits. Two sources of data were used for this thesis: Historical records from the San Juan Basin Research Center, 4-Corners Bull Test (1983 to 2005; n = 2,041) and from the Colorado State University Beef Improvement Center (1993 to 2014; CSU-BIC; n = 8,718). For the 4-Corners study, data of yearling age and breed of cattle were used to determine how PAP varies with regards to both of these effects. The model of birth year, pen, breed, and yearling age effects on yearling PAP revealed these terms were all significant predictors of PAP (P < 0.01). With every one-day increase in yearling age, PAP increased by 0.03 (± 0.01) mm Hg (P < 0.01) with a mean PAP of 45.2 ± 12.8 mm Hg. Breed was found to be a highly significant factor (P < 0.001) in the model influencing PAP scores for bulls developed at high altitude. There was a 13.8-mm Hg range between breeds with the lowest adjusted PAP estimate to those with the highest adjusted PAP. The results suggested that appropriate breed selection based on reduced PAP scores could be advantageous in reducing the susceptibility of cattle to HAD and subsequent death due to pulmonary hypertension and right heart failure. The CSU-BIC data contained production weight traits of birth (36.2 ± 5.1), weaning (213.5 ± 31.8), yearling (345.6 ± 83.9), and post-weaning gain (121.9 ± 63.7) and PAP (42.4 ± 9.9) scores and these data were used to estimate heritabilities and relationships amongst them (mean ± SD; kg). Single-trait, two-trait, and multi-trait models revealed genetic correlations between PAP and the weight traits ranging from -0.11 ± 0.10 to 0.23 ± 0.08. An advantage to using a multi-trait model over a two-trait model is the increase in heritability due to the increase of information from more traits evaluated. Results of this study suggested that selection for lower PAP should not have adverse effects on the growth performance traits evaluated.Item Open Access Trace mineral source impacts rumen trace mineral distribution and fiber digestion in steers fed a low-quality forage-based diet(Colorado State University. Libraries, 2020) Guimaraes, Octavio, author; Engle, Terry, advisor; Geornaras, Ifigenia, committee member; Holt, Timothy, committee memberTwelve Angus steers (BW 452.8 ± 21.8 kg) fitted with ruminal cannulae were used to determine the impact of trace mineral (TM) source on neutral detergent fiber (NDF) digestibility, short chain fatty acid (SCFA) production, ruminal solubility of Cu, Zn, and Mn, and relative binding strength of trace minerals located in the rumen insoluble digesta fraction. Steers were fed a low-quality grass hay diet (DM basis: 10.8% CP, 63.1% NDF, 6.9 mg Cu/kg, 65.5 mg Mn/kg, and 39.4 mg Zn/kg) supplemented with protein for 21 d. Treatments consisted of 20, 40, and 60 mg supplemental Cu, Mn, and Zn/kg DM, respectively, from either sulfate (STM) or hydroxy (HTM) sources (n=6 steers/treatment). Following a 21-d adaptation period, total fecal output was collected for 5 d. Dry matter digestibility tended (P < 0.07) to be reduced (51.9 vs. 53.4 ± 0.52%) and NDF digestibility was reduced (P < 0.04; 40.4 vs. 42.7 ± 0.67%) in STM vs. HTM supplemented steers. On d-6, rumen fluid was collected at 0, 2, and 4 h post feeding and analyzed for SCFA. There were no treatment x time interactions for any response variables measured. However, treatment was a significant (P < 0.05) source of variation for butyric acid and total SCFA production. Steers receiving HTM had less (P < 0.02) butyric acid and greater (P < 0.05) total SCFA than STM supplemented steers. Steers were then fed the same low-quality grass hay diet without supplemental Cu, Zn, or Mn for 14 d. On d-15, steers received a pulse dose of 20 mg Cu, 40 mg Mn, and 60 mg Zn/kg DM from either STM or HTM sources (n=6 steers/treatment). Ruminal samples were obtained at 2-h intervals starting at -4 h and ending at 24 h relative to dosing. There was a treatment x time interaction for ruminal soluble Cu, Mn and Zn concentrations. Ruminal soluble mineral concentrations were greater (P < 0.05) for Cu at 4, 6, 8, 10, 12, and 14 h; for Mn at 4 and 6 h; and for Zn at 4, 6, and 8 h post dosing in STM compared to HTM supplemented steers. Concentrations of Cu and Zn in ruminal solid digesta were also affected by treatment, time, and treatment x time. At 12 h post dosing, Cu and Zn concentrations were greater (P < 0.05) in HTM supplemented steers when compared to STM supplemented steers. Upon dialysis against Tris-EDTA the % Zn released was greater at 12 h (P < 0.03) and 24 h (P < 0.05) and the % Cu released was greater (P < 0.02) at 24 h post dosing when compared to STM supplemented steers. Results indicate that Cu and Zn from HTM have low solubility in the rumen, may improve fiber digestibility and appear to be less tightly bound to ruminal solid digesta than Cu and Zn from STM.