Browsing by Author "Lombard, Jason, committee member"

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Open Access
Effects of pre-milking waiting time and selection behavior in cows milked in an automated batch milking system
(Colorado State University. Libraries, 2025) Weng Zheng, Richard, author; Pinedo, Pablo, advisor; Velez, Juan, committee member; Lombard, Jason, committee member
The adoption of automated milking systems (AMS) has transformed the dairy industry by improving efficiency, animal welfare, and milk production. DeLaval's Batch Voluntary Milking System (Batch VMS) provides a structured alternative to traditional AMS for larger dairy herds. Unlike continuous voluntary milking, Batch VMS organizes cows into groups and schedules their milking at set intervals, enhancing herd management while reducing labor demands. As a hybrid approach, it offers a seamless transition from conventional milking methods to automation. Through a literature review and two research studies, this thesis explores how Batch VMS may affect cow health and performance. Chapter 1 contains the literature review. It introduces the changes in the AMS technologies in recent years and compares it to Batch VMS. Secondly, it discusses the effects of pre-milking waiting time on milking performance and cow health in terms of mastitis and lameness. And lastly, it discusses selection behavior in cows, comparing behaviors in conventional and automated milking systems. Chapter 2 explores the effects of pre-milking waiting time (WT) in an automated batch milking system (ABMS). Visit information was collected to calculate pre-milking WT, defined as the time elapsed between the entrance of the cow to the milking barn, as indicated by pedometers attached to each cow that were read by sensors located at the parlor, and the entrance of each individual cow to the robot milking box. WT were categorized into quartiles within each parity group as Q1 ≤ 9 min, Q2 = 10 to 24 min, Q3 = 25 to 46 min and Q4 ≥ 47 mins for primiparous and Q1 ≤ 11 min Q2 = 12 to 30 min, Q3 = 31 to 51 min and Q4 ≥ 52 mins for multiparous. To assess the association between lameness and WT, individual cow WT averages were calculated separately for primiparous and multiparous groups. Lameness was treated as a categorical variable, where 1 indicated a cow diagnosed with lameness and 0 indicated non-lame cow. The results show that the average waiting time for all milking events was 33.6 min (± SD = 28.5), 34.5 ± 28.9 for PP, and 30.7 ± 27.3 for MP. The means for each breed were 25.6 ± 15.2, 42.3 ± 16.8, and 42.3 ± 23.4, for HO, JE, and HJ, respectively. While significant differences in LSM were observed between breeds for most variables, there was little to no significant association between WT and the analyzed outcomes. An increase of 10 minutes in WT was associated with a 23.7% increase in the odds of lameness in multiparous cows (95% CI: 10.2–39.0; p < 0.001). However, no significant association was found in primiparous cows (OR: 1.09, 95% CI: 0.85–1.38, p = 0.462). Chapter 3 discusses selection behavior in an ABMS where cows select between 22 robots each time there are brought to the milking parlor. The objective of this study was to analyze the robotic milking station selection behavior of three breeds including Holstein, Jersey, and Holstein × Jersey crossbred cows in a multibreed dairy farm with a batch milking system with automatic milking units. The study used data from 1,762,461 milking events in 3705 HO (n=1355), JE (1876) and HJ (475) cows from May 2023 to September 2024 in a commercial organic grass-fed dairy in TX. Cows were moved to the milking center twice per day, where they could select their milking visits among 22 robot units (DeLaval, Sweden). For the analysis, robots were also classified by barn location [East (n=11); West] and arm configuration [left (n=11); right]. Milking visit information was collected to determine the frequency of specific robot usage per cow during the study period. Subsequently, the frequencies of selection for the top 1, 3, and 5 robotic milking stations, top barn location, and top arm configuration were calculated for each cow. Preference consistency scores (PCS) were calculated considering the frequency of access to each robotic milking station, barn side, and arm configuration in 30 days periods. Overall, multiparous and HO cows evidenced more consistent behaviors in milking station preference. Dairy cow selection behavior should be considered when analyzing the efficiency of milking procedures.
Open Access
Evaluation of novel strategies for improving health and wellbeing of dairy cattle
(Colorado State University. Libraries, 2018) Paudyal, Sushil, author; Pinedo, Pablo J., advisor; Roman-Muniz, Ivette Noami, committee member; Callan, Robert J., committee member; Lombard, Jason, committee member; Melendez, Pedro, committee member; Maunsell, Fiona, committee member
To view the abstract, please see the full text of the document.
Open Access
Individual quarter dry-off procedure in dairy cows
(Colorado State University. Libraries, 2025) Ibarguren, Clara, author; Pinedo, Pablo, advisor; Velez, Juan, committee member; Lombard, Jason, committee member
Mastitis, defined as inflammation of the mammary gland, has a major impact on the dairy industry, affecting profitability and animal welfare due to reduced milk production, increased antibiotic use, and pain and discomfort in the affected animals. This health disorder concerns researchers, producers, and consumers worldwide. The "individual quarter dry-off" procedure, which consists of stopping milking the affected quarter is an alternative to the use of antibiotic treatment in unresponsive cases. Understanding the relationship between the multiple factors involved in the disease and this procedure is crucial. Through an extensive review of mastitis and a descriptive statistical analysis of this dry-off practice, this thesis focuses on understanding the dynamics of this procedure within a lactating dairy herd. Chapter 1 includes a literature review on mastitis, and the possible management practices conducted by the dairy industry to mitigate the problem. Due to the limited information available on individual quarter dry-off, the information provided in this chapter consists of a discussion of the anatomy of the mammary gland, physiology, pathology of mastitis disease, and management practices. Once general knowledge of the root of the problem is established, technical implications regarding the individual dry-off procedure are explained in the following chapter. The objective of chapter 2 is to describe the dynamics of individual quarter dry-offs in certified organic dairies. The data were collected from PCDart (©DRMS) spanning from 2018 to 2023 from four organic dairies in CO, USA. The dataset included 2,881 cows with at least one dried quarter (QDO), of which 769 cows (26%) had a second dried quarter (QDO2). The variables considered in this study were quarter location, parity, days in milk (DIM), season, and survival after the first quarter dry-off (QDO). The statistical analysis was completed in SAS (SAS Institute Inc.), employing chi-square goodness of fit, logistic regression, and ANOVA. The results showed that QDO was more prevalent in front quarters among both primiparous (PP) and multiparous (MP) cows, with higher frequencies observed during winter across both parity categories. The mean ± SE of days in milk at QDO was smaller for primiparous cows compared to multiparous cows, and it took approximately one year to have a second dried quarter to occur. Parity category had no effect on the likelihood of QDO2, and the number of days to culling after QDO were not significantly different between parities, averaging around 365 days. Additionally, cows with QDO had lower actual and projected 305 milk yield compared to healthy cows (597 kg [PP] and 436 kg [MP] less for actual 305 milk production; 628 kg [PP] and 495 kg [MP] less for projected 305 milk production). Overall, milk yield was consistently lower in cows with QDO compared to their herdmates. These findings provide valuable insights into the dynamics of quarter dry-off, contributing novel information to support the control of mastitis in certified organic dairies. Chapter 3 explores the dynamics of milk yield following the individual dry-off of quarters (QDO) in dairy cows. The study focused on cows that had one quarter dried off due to a chronic mastitis event and had milking records available for 30 days post-procedure. Data were collected from 144 cows on an automatic milking system (AMS) dairy farm in Colorado, of which 79% (n=144) were multiparous and 21% (n=30) primiparous. Information was sourced from DelPro and DairyComp on-farm software, and linear mixed models with repeated measures and estimated marginal means (emmeans) were generated using RStudio. Although the sample size of primiparous cows was limited, results showed a slight decrease in milk production following QDO. Conversely, multiparous cows displayed increased production in the opposite quarters, with an overall milk yield rising over the 30-day period after the dry-off. Total milk production following QDO was higher in cows ≤120 days in milk (DIM) compared to those with >120 DIM. Additionally, cows experienced greater milk yields when the dry-off procedure was performed on rear quarters versus front quarters. Of the variables analyzed, the number of days in milk after the procedure showed the most statistically significant relationship with milk production, while presence of other diseases did not exhibit a significant effect. These findings offer valuable insights into milk yield dynamics and implications for management strategies in dairy herds.
Open Access
Influence of early life management strategies on indicators of health and performance in pre-weaned dairy calves and mature cows
(Colorado State University. Libraries, 2021) Velasquez Munoz, Ana Karina, author; Pinedo, Pablo, advisor; Lombard, Jason, committee member; Rao, Sangeeta, committee member; Roman Muniz, Ivette Noami, committee member
To view the abstract, please see the full text of the document.
Open Access
The epidemiology and ecology of Escherichia coli O157 on U.S. dairies
(Colorado State University. Libraries, 2018) Stenkamp-Strahm, Chloe Marie, author; Reynolds, Stephen, advisor; McConnel, Craig, advisor; Magzamen, Sheryl, committee member; Lombard, Jason, committee member; Abdo, Zaid, committee member
Escherichia coli O157 (O157) is a bacterium that causes human foodborne disease outbreaks worldwide. Beef and dairy cattle are reservoirs for O157, as they harbor the bacteria in their lower gastrointestinal (GI) tracts and shed it in feces without clinical illness. Humans become infected with O157 after contacting cows or manure, or ingesting the bacteria on dairy, meat or produce products. Dairy cattle are a central part of the U.S food supply, providing milk for a multitude of dairy products, and 15-20% of the beef produced. Transmission of O157 from dairy cattle to humans is reduced by techniques that limit bacterial survival after food is harvested (i.e. post-harvest). However, O157 outbreaks occur after post-harvest dairy pasteurization and slaughter laws are applied across the U.S food chain. Due to these outbreaks, an emphasis has been placed on developing methods that reduce O157 presence prior to harvest (i.e pre-harvest) at the dairy farm. An understanding of dairy cow O157 prevalence and magnitude of shedding, and animal-level correlates for shedding, may aid in the development of pre-harvest O157 strategies. We hypothesized that life history features (parity, history of disease, others) would be associated with O157 shedding by adult cows on Colorado dairies, and that shedding in early lactation would be correlated with shedding detected during the pre-weaning period of these dams' calves. Although overall prevalence was low (3.0%) and only one individual shed O157 at a high magnitude (>103 CFU/g feces), a higher number of adult cows shed O157 between June and October. Dams were at increased risk of shedding if they were a lower parity, earlier days in milk, or had a history of antibiotic use. Calf shedding was not detected on the Colorado dairies studied; no correlation between dam and calf O157 shedding was present. We hypothesized that the lack of calf shedding was due to the sampling time-frame, calf management, and the geographic region of study. Using fecal samples collected by the National Animal Health Monitoring System (NAHMS) from dairy calves across the U.S, we estimated the prevalence of O157 shedding and managerial, environmental, and calf-level variables associated with pathogen presence. U.S calf shedding of O157 was low (2.5 %) and not influenced by geographic region. Calves were at increased risk to shed if they received colostrum from their own dam, which suggests that increased time spent with the dam is associated with shedding. Results indicated that the passive transfer status of calves also influenced shedding, but was affected by the temperature and humidity index (THI) calves were exposed to during pre-weaning. Calves experiencing thermoneutral or heat-stress THIs were more likely to shed O157 if they had poor or moderate passive transfer. Calves were unlikely to shed if they had excellent passive transfer, regardless of THI. Herds of cattle likely have uniform levels of O157 exposure, but only some individuals shed the bacteria. We hypothesized that the GI microbial community influenced which cows become colonized with O157 post-ingestion. After measuring microbial communities in naturally infected cows on Colorado dairies, lower microbial richness (i.e. total number of unique species) was associated with intermittent or multi-day shedding of O157. The species Bacillus coagulans was lower in abundance in fecal samples that contained O157, while the genus Moryella spp was higher in abundance. The results of this dissertation highlight factors associated with O157 shedding by dairy cows and calves. This information may be used when developing techniques that reduce transmission between dairy cows, or dissemination of O157 beyond the dairy. Because O157 does not adversely affect cows, the future adoption of O157 mitigation strategies relies on whether or not these approaches benefit the dairy operation. Based on our results, we hypothesize that ill health and cow stress is associated with shedding, but is difficult to measure and monetarily quantify. At the current time, development of reduction strategies should focus on methods that reduce O157 while simultaneously improving cow health and production (e. g reducing stress during cow transition periods, improving passive transfer and limiting dam exposure of calves, feeding probiotics that improve GI health, creating multi-pathogen vaccines). We propose that future studies should also focus on determining whether O157 augments milk production and cow fertility.