Recent beak evolution in North American starlings after invasion

European starlings are one of the most abundant and problematic avian invaders in the world. From their native range across Eurasia and North Africa, they have been introduced to every continent except Antarctica. In 160 years, starlings have expanded into different environments throughout the world, making them a powerful model for understanding rapid evolutionary change and adaptive plasticity. Here, we investigate their spatiotemporal morphological variation in North America and the native range. Our dataset includes 1217 specimens; a combination of historical museum skins and modern birds. Beak length in the native range has remained unchanged during the past 206 years, but we find beak length in North American birds is now 8% longer than birds from the native range. We discuss potential drivers of this pattern including dietary adaptation or climatic pressures. Additionally, body size in North American starlings is smaller than those from the native range, which suggests a role for selection or founder effect. Taken together, our results indicate rapid recent evolutionary change in starling morphology coincident with invasion into novel environments.

Effect of Antimicrobial Use in Conventional Versus Natural Cattle Feedlots on the Microbiome and Resistome

Antimicrobial use (AMU) in the livestock industry has been associated with increased levels of antimicrobial resistance. Recently, there has been an increase in the number of "natural" feedlots in the beef cattle sector that raise cattle without antibiotics. Shotgun metagenomics was employed to characterize the impact of AMU in feedlot cattle on the microbiome, resistome, and mobilome. Sequenced fecal samples identified a decline (q < 0.01) in the genera Methanobrevibacter and Treponema in the microbiome of naturally vs. conventionally raised feedlot cattle, but this difference was not (q > 0.05) observed in catch basin samples. No differences (q > 0.05) were found in the class-level resistome between feedlot practices. In fecal samples, decreases from conventional to natural (q < 0.05) were noted in reads for the antimicrobial-resistant genes (ARGs) mefA, tet40, tetO, tetQ, and tetW. Plasmid-associated ARGs were more common in feces from conventional than natural feedlot cattle. Interestingly, more chromosomal- than plasmid-associated macrolide resistance genes were observed in both natural and conventional feedlots, suggesting that they were more stably conserved than the predominately plasmid-associated tetracycline resistance genes. This study suggests that generationally selected resistomes through decades of AMU persist even after AMU ceases in natural production systems.

Comparative growth performance of backgrounded beef heifers treated with an injectable fixed-dose combination (0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride) or single-active (0.2 mg/kg ivermectin) endectocide

Gastrointestinal nematodes (GINs) can negatively impact all production classes of cattle, particularly growing cattle. A global decline in efficacy of broad-spectrum single-active anthelmintics requires alternative GIN control methods without the aid of novel drug classes. Here, we present a new fixed-dose combination injectable (FDCI) endectocide for cattle that combines doramectin (5 mg/ml) and levamisole hydrochloride (150 mg/ml). A 56-day comparative performance confinement backgrounding trial was conducted in stocker beef heifers (n = 1548) with confirmed GIN infections to (1) compare the Day 14 post-treatment effectiveness of the new FDCI endectocide to pen mates treated with the injectable single-active endectocide ivermectin, as evidenced by fecal egg counts (FECs) conducted for a randomly selected subset (10%) of both treatment groups, and (2) determine if the greater GIN control by the FDCI evidenced in the subsample improved growth performance in all FDCI-treated heifers. Heifers were procured in four cohorts, with a 10-week timeframe between enrollment of the first and last cohort. Treatment groups were comingled within dirt-floor pens (n = 31; 7-8 per cohort) and offered a standard backgrounding diet ad libitum for the study duration. Heifers with enrollment FEC ≥ 30 eggs per gram (EPG) were randomly allocated to receive the FDCI (n = 773) or ivermectin (n = 775) on Day 0. Day 0 FECs conducted on 10% of enrolled heifers (FDCI, n = 78; ivermectin, n = 79) were not different between treatment groups (p = 0.491). Day 14 FECs for the same heifers were reduced compared to Day 0 within each treatment group. Heifers given the FDCI had lower Day 14 AM FECs and higher FEC reduction test (FECRT) result (0.07 EPG; 0.999) than ivermectin-treated heifers (21.58 EPG; FECRT = 0.850). Mean body weight (BW) was not different between treatment groups on Day 0 (p = 0.2762) and Day 14 (p = 0.2010) but was significantly greater (p = 0.0007) for FDCI-treated heifers compared to ivermectin-treated heifers on Day 56. Compared to ivermectin-treated heifers, overall average daily gain from all evaluation periods (Day 0-14, Day 14-56, and Day 0-56) was greater (p ≤ 0.0052) in FDCI-treated heifers, and FDCI-treated heifers had 4.223 kg greater total weight gain over the 56-day study. The FDCI (0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride) was highly effective in reducing GIN infections and thus promoted improved growth performance in beef heifers over a 56-day backgrounding period.

Disease Occurrence in- and the Transferal of Zoonotic Agents by North American Feedlot Cattle

North America is a large producer of beef and contains approximately 12% of the world's cattle inventory. Feedlots are an integral part of modern cattle production in North America, producing a high-quality, wholesome protein food for humans. Cattle, during their final stage, are fed readily digestible high-energy density rations in feedlots. Cattle in feedlots are susceptible to certain zoonotic diseases that impact cattle health, growth performance, and carcass characteristics, as well as human health. Diseases are often transferred amongst pen-mates, but they can also originate from the environment and be spread by vectors or fomites. Pathogen carriage in the gastrointestinal tract of cattle often leads to direct or indirect contamination of foods and the feedlot environment. This leads to the recirculation of these pathogens that have fecal-oral transmission within a feedlot cattle population for an extended time. Salmonella, Shiga toxin-producing Escherichia coli, and Campylobacter are commonly associated with animal-derived foods and can be transferred to humans through several routes such as contact with infected cattle and the consumption of contaminated meat. Brucellosis, anthrax, and leptospirosis, significant but neglected zoonotic diseases with debilitating impacts on human and animal health, are also discussed.

Associations of Work-Related Injuries and Stress to Family and Youth Wellbeing among U.S. Latino/a Immigrant Cattle Feedyard Workers

Based on the Ecological Stress-Based Model of Immigrant Worker Safety and Health, we hypothesized that occupational stress and physical safety would be negatively linked to workers' depression, which in turn, would increase family conflict and decrease youth prosocial behaviors. A total of 242 Latino immigrant cattle feedyard workers from Nebraska and Kansas (90.9% male; M age = 37.7 years) answered questions assessing depression, occupational stress, whether they had ever been injured at work, familial conflict, and youth prosocial behaviors. All four indirect relations among occupational stress and injury and the outcomes (family conflict and youth prosocial behaviors) via depressive symptomatology were significant. Additionally, ever injured was negatively related to youth prosocial behaviors and occupational stress was positively related to youth prosocial behaviors. The findings support our model and suggest that increased stress and work-related injuries on cattle feedyards are linked to mental health problems, which in turn, is linked to more conflict experienced at home and less youth prosocial behaviors. Feedyard employers should focus on improving safety culture including providing robust training in the workplace. Practical implications to improve availability and access to mental and behavioral health resources to mitigate negative family outcomes are provided.

Individual Beef Cattle Identification Using Muzzle Images and Deep Learning Techniques

Individual feedlot beef cattle identification represents a critical component in cattle traceability in the supply food chain. It also provides insights into tracking disease trajectories, ascertaining ownership, and managing cattle production and distribution. Animal biometric solutions, e.g., identifying cattle muzzle patterns (unique features comparable to human fingerprints), may offer noninvasive and unique methods for cattle identification and tracking, but need validation with advancement in machine learning modeling. The objectives of this research were to (1) collect and publish a high-quality dataset for beef cattle muzzle images, and (2) evaluate and benchmark the performance of recognizing individual beef cattle with a variety of deep learning models. A total of 4923 muzzle images for 268 US feedlot finishing cattle (>12 images per animal on average) were taken with a mirrorless digital camera and processed to form the dataset. A total of 59 deep learning image classification models were comparatively evaluated for identifying individual cattle. The best accuracy for identifying the 268 cattle was 98.7%, and the fastest processing speed was 28.3 ms/image. Weighted cross-entropy loss function and data augmentation can increase the identification accuracy of individual cattle with fewer muzzle images for model development. In conclusion, this study demonstrates the great potential of deep learning applications for individual cattle identification and is favorable for precision livestock management. Scholars are encouraged to utilize the published dataset to develop better models tailored for the beef cattle industry.

Occupational Injuries among Latino/a Immigrant Cattle Feedyard Workers in the Central States Region of the United States

Agriculture is a dangerous industry with high rates of occupational injuries. Immigrants comprise the majority of the hired agricultural workforce in the United States, and these workers may be at a higher risk for job-related injuries. This study addressed the frequency, characteristics, and risk factors of occupational injuries among Latino immigrant cattle feedyard workers. Data were collected through structured interviews with Latino immigrant cattle feedyard workers in Kansas and Nebraska (n = 243; 90.9% male). Descriptive statistics and logistic regression were used to identify risk factors for injury. Nearly three-fourths of participants (71.2%) reported having experienced one or more injuries in the past while working on a cattle feedyard. The most frequent types of reported injuries, including those not requiring medical care, were bruises/contusions (40%), cuts/lacerations (21%), and sprains/strains (12%). These injuries were mainly caused by animals/livestock (33%), chemicals (23%), falls (12%), and tools (9%). Significant risk factors for injury included male gender (OR 5.9), being over age 35 (OR 2.6), working on a large or an extra-large feedyard (OR 5.4), having 11 or more employees on the feedyard (OR 3.6), and working more than eight hours a day (OR 4.7). Having received safety training was also associated with greater risk of injury in a univariable model (OR 2.6). Cattle feedyard workers are at high risk for injury and require more effective preventive measures.

Fatigue and the Need for Recovery among Latino/a Immigrant Cattle Feedyard Workers

Cattle feedyards are animal feeding operations where beef cattle are finished to market weight on grain. Cattle feeding can be dirty, demanding, and dangerous work. This study sought to assess the predictors of fatigue and the need for recovery among Latino/a immigrant cattle feedyard workers in the United States. A path model was examined to explore direct and indirect relations among physical fatigue, mental fatigue, need for recovery, job characteristics, and health and sociodemographic covariates. Lower self-reported health, experiencing physical pain, not handling animals, and decreased decision latitude were directly related to increased physical fatigue. Shorter tenure working on cattle feedyards, lower educational level, experiencing physical pain, and increased job demands were directly related to heightened mental fatigue. Being female, experiencing physical pain, an elevated average of hours worked per day, increased job demands, and less decision latitude were directly related to an increased need for recovery and indirectly related to both physical and mental fatigue. Physical and mental fatigue have specific correlates, but job characteristics, including job demands and decision latitude, can directly and indirectly impact workers' levels of physical and mental fatigue and their need for recovery. Both preventive measures and restructuring work operations may reduce the risk for fatigue and the need for recovery. Implications for cattle feedyard workers, supervisors, and employers are discussed. Finding ways to balance productivity and the well-being of workers should be a high priority for cattle feedyards across the country.

Reduced space in outdoor feedlot impacts beef cattle welfare

There is a trend to reduce the space allowance per animal in cattle feedlot, despite its potential negative impact on animal welfare. Aiming to evaluate the effects of space allowance per animal in outdoor feedlots on beef cattle welfare, a total of 1350 Nellore bulls (450 pure and 900 crossbred) were confined for 12 weeks using three space allowances: 6 (SA6), 12 (SA12) and 24 (SA24) m2/animal (n = 450 per treatment). Bulls were housed in three pens per treatment (n = 150 per pen). The first 6 weeks in the feedlot were defined as 'dry' and the last as 'rainy' period, according to the accumulated precipitation. Animal-based (body cleanliness, health indicators and maintenance behaviour) and environmental-based indicators (mud depth and air dust concentration) were assessed weekly during the feedlot period. Most of the health indicators (nasal and ocular discharge, hoof and locomotion alterations, diarrhoea, bloated rumen and breathing difficulty) were assessed in a subset of 15 animals randomly selected from each pen. Coughs and sneezes were counted in each pen. Maintenance behaviours (number of animals lying and attending the feed bunk) were recorded with scan sampling and instantaneous recording at 20-min intervals. Postmortem assessments were carried out in all animals by recording the frequencies of macroscopic signs of bronchitis, pulmonary emphysema, nephritis and urinary cyst and by measuring the weight and cortical and medullar areas of adrenal glands (n = 30 per pen). Compared with SA12 and SA24, SA6 showed a greater number of sneezes per minute during the dry period and a greater percentage of animals with locomotion alterations during the rainy period. Coughing, diarrhoea and nasal discharge affected a larger number of animals in the SA6 relative to the other two groups. During the rainy period, there was a lower percentage of animals with nasal and ocular discharge, and a greater percentage of animals with abnormal hoof and lying. A lower percentage of animals in SA6 and SA12 (but not SA24) attended the feed bunk during the rainy relative to the dry period. A mud depth score of 0 (no mud) was most frequent in SA24 pens, followed by SA12 and then SA6. Adrenal gland weight and cortical area were lower in SA24 animals compared with those in SA6 and SA12. The results show that decreasing the space allowance for beef cattle in outdoor feedlots degrades the feedlot environment and impoverishes animal welfare.

A Preliminary Analysis of Immigrant Cattle Feedyard Worker Perspectives on Job-Related Safety Training

Immigrants comprise a large percentage of the agricultural labor force in the United States. They are a vulnerable worker population and often have fewer occupational and social protections. Latino immigrant cattle feedyard workers (N = 68; 59 men; mean age = 38.7 years) in the central Midwest reported on their perceptions and preferences for job-related safety training and practices. Preliminary findings indicate that approximately 40% of workers reported that they had not received any health or safety training from their current employer, and only about 13% had ever participated in any Occupational Safety and Health Administration (OSHA) safety training program. In-person training, videos, or shadowing another worker were the most frequent methods of safety training reported by those who had received training. More than 90% were interested in receiving more information about health and safety related to their job. Workers preferred that safety information be provided through in-person training at the job site, videos (particularly those accessible through media sources such as YouTube), and written materials. Specific topics that workers were interested in obtaining more information about included zoonoses, low-stress cattle handling, injury prevention, hazard and injury reporting, chemical and equipment safety, and teamwork. Furthermore, a majority of participants preferred to receive information in Spanish. Results may help guide the development of future materials and training strategies to better suit the needs of the growing immigrant workforce in production agriculture.