Automated dairy cattle lameness detection utilizing the power of artificial intelligence; current status quo and future research opportunities.

Lameness represents a major welfare and health problem for the dairy industry across all farming systems. Visual mobility scoring, although very useful, is labour-intensive and physically demanding, especially in large dairies, often leading to inconsistencies and inadequate uptake of the practice. Technological and computational advancements of artificial intelligence (AI) have led to the development of numerous automated solutions for livestock monitoring. The objective of this study was to review the automated systems using AI algorithms for lameness detection developed to-date. These systems rely on gait analysis using accelerometers, weighing platforms, acoustic analysis, radar sensors and computer vision technology. The lameness features of interest, the AI techniques used to process the data as well as the ground truth of lameness selected in each case are described. Measures of accuracy regarding correct classification of cows as lame or non-lame varied with most systems being able to classify cows with adequate reliability. Most studies used visual mobility scoring as the ground truth for comparison with only a few studies using the presence of specific foot pathologies. Given the capabilities of AI, and the benefits of early treatment of lameness, longitudinal studies to identify gait abnormalities using automated scores related to the early developmental stages of different foot pathologies are required. Farm-specific optimal thresholds for early intervention should then be identified to ameliorate cow health and welfare but also minimise unnecessary inspections.

End-of-life decision-making of dairy cattle and calves: A survey of British farmers and veterinary surgeons.

Background: The study aim was to characterise issues faced by farmers and veterinary surgeons when making end-of-life decisions for dairy cattle. Methods: Online surveys were distributed to British dairy farmers and veterinary surgeons for 20 weeks from November 2020. Results: There were 83 responses (37 farmers, 46 veterinary surgeons). Among youngstock, the risk of unassisted/natural death (2.6% ± 0.3%) was almost double the risk of euthanasia (1.4% ± 0.3%; p = 0.003). The opposite, however, was true in the milking herd: the risk of euthanasia (2.3% ± 0.3%) was greater than unassisted/natural death (1.6% ± 0.2%; p = 0.05). A fallen stock collector (62%) typically performed euthanasia and most farms (66%) did not have anyone trained to perform euthanasia. Most deaths within the milking herd were attributed to 'unknown or not recorded' (median 15% of deaths). The factors that farmers most frequently reported as strongly influencing their decision of when to euthanase an animal relative to the onset of disease were 'failure to respond to treatment' (89%), 'veterinary advice' (89%) and 'severity of disease' (88%). On average, veterinarians had moderate or high confidence that 60% of dairy farm clients 'are performing euthanasia in a timely manner so as to prevent unnecessary suffering'. Veterinary surgeons had variable agreement on the time to euthanasia for various conditions. Conclusions: The survey highlighted end-of life decision-making successes and areas for improvement on dairy farms. An evidence-based, decision-support framework may help end-of-life decision-making, particularly for complex diseases.

Hypoxia induces an increase in intestinal permeability and pulmonary arterial pressures in neonatal Holstein calves despite feeding the flavonoid rutin.

The purposes of this study were to determine whether the naturally occurring flavonoid quercetin, as its glucorhamnoside rutin, reduces intestinal permeability and susceptibility to hypoxia-induced pulmonary hypertension in neonatal Holstein calves. A 2 × 2 between-subjects factorial design was conducted using Holstein steers (n = 16). Factors included oxygen level (simulated altitude of 4,572 m vs. 975 m) and quercetin supplementation as its glucorhamnoside rutin (4 g of quercetin per day vs. 0 g per day). Two days after arrival (d 0 of study) the calves were blocked by body mass into treatment groups, and treatments were initiated. Pulmonary arterial pressure, echocardiography, and serum concentrations of orally administered lactulose (0.45 g/kg) and mannitol (0.15 g/kg) were measured on d 12, 13, and 14, respectively. Calves were euthanized on d 15 and pulmonary tissues collected for semiquantitative scoring of histological lesions. Data were analyzed using linear regression, generalized estimating equations, and 2-sample proportion tests. Hypoxia, but not rutin, was found to be associated with intestinal permeability. The lactulose-mannitol ratio was 0.54 ± 0.13 (standard error) in hypoxic calves and 0.02 ± 0.13 in normoxic controls. Hypoxia increased mean pulmonary arterial pressure. Calves fed rutin under hypoxic conditions tended to have a lower mean pulmonary arterial pressure (59 ± 7 mmHg) than control calves (80 ± 7 mmHg) but similar pressures under normoxic conditions. Paradoxically, however, a greater proportion of calves fed rutin had histological evidence of pulmonary arteriolar medial hypertrophy and adventitial hyperplasia than did controls. In conclusion, the findings of this study indicate that hypoxia increased intestinal permeability in neonatal calves. The flavonoid quercetin, as its glucorhamnoside rutin, had no protective effect on intestinal permeability, and, although it tended to reduce the severity of hypoxia-induced pulmonary hypertension, a greater proportion of calves fed rutin had histological lesions consistent with pulmonary arteriolar remodeling.

Cardiopulmonary remodeling in fattened beef cattle: a naturally occurring large animal model of obesity-associated pulmonary hypertension with left heart disease.

The obesity epidemic in developed societies has led to increased cardiovascular diseases including pulmonary hypertension associated with left heart disease (PH-LHD), the largest and fastest-growing class of PH. Similar to obese humans, PH and heart failure (HF) are increasingly recognized in North American fattened beef cattle. We hypothesized that PH and HF in fattened beef cattle are novel, phenotypically distinct manifestations of bovine PH arising from left ventricular (LV) dysfunction similar to obesity-related PH-LHD in humans. We conducted a semi-quantitative histopathological assessment of cardiopulmonary tissues obtained from fattened beef cattle suffering end-stage HF compared to asymptomatic cattle of equivalent age undergoing the same fattening regimens. In HF animals we observed significant LV fibrosis, abundant cardiac adipose depots, coronary artery injury, and pulmonary venous remodeling recapitulating human obesity-related PH-LHD. Additionally, striking muscularization, medial hypertrophy, adventitial fibrosis, and vasa vasorum hyperplasia in the pulmonary arterial circulation were associated with sequela of pathologic right ventricular (RV) remodeling suggesting combined pulmonary venous and arterial hypertension. The association between obesity, pathologic cardiopulmonary remodeling, and HF in fattened beef cattle appears to recapitulate the complex pathophysiology of obesity-associated PH-LHD in humans. This novel, naturally occurring, and large animal model may provide mechanistic and translational insights into human disease.

Preliminary evidence that hydrostatic edema may contribute to the formation of diffuse alveolar damage in a Holstein calf model.

Background: Two notable findings of clinically healthy feedlot cattle suggest they may have pulmonary hydrostatic edema during the finishing phase of production: increased pulmonary arterial wedge pressures and pulmonary venous hypertrophy. The goal of this study was to determine if increased pulmonary arterial wedge pressure (PAWP) in a Holstein calf could lead to diffuse alveolar damage consistent with the early, exudative phase of acute interstitial pneumonia of feedlot cattle. Methods: Six male Holstein dairy calves were given daily subcutaneous injections of the nonspecific ß-adrenergic agonist isoprenaline (10 mg/kg/d), to induce left ventricular diastolic dysfunction, or sterile water for 14 days. On Day 14, pulmonary arterial pressures and wedge pressures were measured, echocardiography performed, and the ratio of mitral valve flow velocity (E) to septal lengthening velocity (e') calculated. Calves were euthanized on Day 15 and lung lesions semi-quantitatively scored. Results: Mean PAWP was 12 ± 1 mm Hg in calves that received isoprenaline and 7 ± 1 mm Hg in controls ( P = 0.01). Calves that received isoprenaline tended to have greater relative wall thickness than control calves ( P = 0.15) and greater E/e' ratios ( P = 0.16), suggestive of concentric hypertrophy and diastolic dysfunction, respectively. Calves that received isoprenaline also tended to have a left ventricle and interventricular septum that was 29 ± 10 g heavier than control calves ( P = 0.10) when controlling for body mass. Hyaline membranes, the hallmark feature of diffuse alveolar damage, were evident in lung sections from all calves that received isoprenaline but none of the controls. Conclusions: Consistent with prior pathological and physiological studies of feedlot cattle, this study provides preliminary evidence that cattle presenting with clinical signs and pathology consistent with early stage acute interstitial pneumonia could be attributable to hydrostatic edema associated with left ventricular failure.

Successful treatment of suckling Red Angus calves for bovine respiratory disease is not associated with increased mean pulmonary arterial pressures at weaning.

The purposes of this study were to determine if the successful treatment of bovine respiratory disease (BRD) in suckling calves was associated with a long-term increase in mean pulmonary arterial pressure (mPAP) and, to screen for associations between blood leukogram variables and mPAP. A cohort of Red Angus calves (n = 74) were followed from birth to weaning at an altitude of 975 m. Calves were weaned at 172 ± 14 d when their mPAP was measured and whole blood collected. Thirty calves that had been treated for BRD (34 to 45 d prior) and 30 calves that had not required treatment for BRD were sampled. Treatment for BRD had no effect on mPAP (P = 0.37). Mean mPAP was 48 ± 8 mm Hg (± SD) with a minimum of 34 mm Hg and a maximum at 69 mm Hg. Weaning weight and sex tended to be associated with mPAP, but they explained just 5% of the variation in mPAP (P = 0.08; Adj. r2 = 0.05). Fibrinogen (P = 0.008) and absolute lymphocyte count (P = 0.06) were negatively associated with mPAP, whereas absolute monocyte count was positively associated with mPAP (P = 0.01). The findings of this study suggest that pre-weaning treatment for BRD does not increase a calves' post-weaning risk of congestive right heart failure. Further, components of the immune and acute phase response system may play a role in the development and progression of pulmonary hypertension.

Surgical placement of a wireless telemetry device for cardiovascular studies of bovine calves.

Background: Domestic cattle ( Bos taurus) are naturally susceptible to hypoxia-induced pulmonary arterial hypertension; consequently, the bovine calf has been used with considerable success as an animal model of the analogous human condition. Studies to date, however, have relied on instantaneous measurements of pressure and cardiac output. Here, we describe the surgical technique for placement of a fully implantable wireless biotelemetry device in a bovine calf for measurement of pulmonary arterial and left ventricular pressures, right ventricular output, and electrocardiogram. Methods: Three, 2-month old bovine calves underwent left-sided thoracotomies. A transit-time flow probe was placed around the pulmonary artery and solid-state pressure catheters inserted into the pulmonary artery and left ventricle. Biopotential leads were secured to the epicardium. The implant body was secured subcutaneously, dorso-caudal to the incision. Results: The implant and sensors were successfully placed in two of the three calves. One calf died from ventricular fibrillation following left ventricular puncture prior to pressure sensor insertion. Anatomical discrepancies meant that either 4 th or 5 th rib was removed. The calves recovered quickly with minimal complications that included moderate dyspnea and subcutaneous edema. Conclusions: Left thoracotomy is a viable surgical approach for wireless biotelemetry studies of bovine calf cardiovascular function. The real-time, contemporaneous collection of cardiovascular pressures and output, permits pathophysiological studies in a naturally susceptible, large animal model of pulmonary arterial hypertension.

Right Ventricular Longitudinal Strain Is Depressed in a Bovine Model of Pulmonary Hypertension.

BACKGROUND: Pulmonary hypertension and resulting right ventricular (RV) dysfunction are associated with significant perioperative morbidity and mortality. Although echocardiography permits real-time, noninvasive assessment of RV function, objective and comparative measures are underdeveloped, and appropriate animal models to study their utility are lacking. Longitudinal strain analysis is a novel echocardiographic method to quantify RV performance. Herein, we hypothesized that peak RV longitudinal strain would worsen in a bovine model of pulmonary hypertension compared with control animals. METHODS: Newborn Holstein calves were randomly chosen for induction of pulmonary hypertension versus control conditions. Pulmonary hypertension was induced by exposing animals to 14 days of hypoxia (equivalent to 4570 m above sea level or 430 mm Hg barometric pressure). Control animals were kept at ambient pressure/normoxia. At the end of the intervention, transthoracic echocardiography was performed in awake calves. Longitudinal wall strain was analyzed from modified apical 4-chamber views focused on the RV. Comparisons between measurements in hypoxic versus nonhypoxic conditions were performed using Student t test for independent samples and unequal variances. RESULTS: After 14 days at normoxic versus hypoxic conditions, 15 calves were examined with echocardiography. Pulmonary hypertension was confirmed by right heart catheterization and associated with reduced RV systolic function. Mean systolic strain measurements were compared in normoxia-exposed animals (n = 8) and hypoxia-exposed animals (n = 7). Peak global systolic longitudinal RV strain after hypoxia worsened compared to normoxia (-10.5% vs -16.1%, P = 0.0031). Peak RV free wall strain also worsened after hypoxia compared to normoxia (-9.6% vs -17.3%, P = 0.0031). Findings from strain analysis were confirmed by measurement of tricuspid annular peak systolic excursion. CONCLUSIONS: Peak longitudinal RV strain detected worsened RV function in animals with hypoxia-induced pulmonary hypertension compared with control animals. This relationship was demonstrated in the transthoracic echocardiographic 4-chamber view independently for the RV free wall and for the combination of the free and septal walls. This innovative model of bovine pulmonary hypertension may prove useful to compare different monitoring technologies for the assessment of early events of RV dysfunction. Further studies linking novel RV imaging applications with mechanistic and therapeutic approaches are needed.

Impaired alveolar-arterial oxygen transfer is associated with reduced milk yield in primiparous post-partum dairy heifers at moderate altitude.

Domestic cattle have limited cardiopulmonary reserve for their body size and oxygen requirements. Therefore, it is plausible that impaired alveolar-arterial gas exchange may be detrimental to energetically expensive traits such as milk production which, like all aerobic processes, requires oxygen. The degree of alveolar-arterial oxygen transfer impairment can be determined by estimating the alveolar-arterial oxygen (A-a O2) pressure gradient from arterial blood-gas tensions. The degree of oxygen transfer impairment is proportional to the A-a O2 pressure gradient: the higher the A-a O2 pressure gradient the less oxygen is transferred to the blood for a given ventilation rate. In this study two cohorts of Holstein-Friesian heifers were followed on one northern Colorado dairy farm. Arterial blood-gas analyses were performed up to 9 d post-calving. Heifers were grouped into quartiles based on A-a O2 pressure gradient so that relative comparisons could be made. Heifers in the lowest (Q1) and highest (Q4) quartile had the least and greatest impairment of alveolar-arterial oxygen transfer, respectively. We hypothesised that milk yield over 60 d would be greatest for heifers in Q1 and would decrease with quartile increments. Hyperventilation, as indicated by hypocapnia, was notable. Despite hypoxia, haematocrit was low. Alveolar-arterial O2 pressure gradient was associated with milk production (P=0·03) when controlling for cohort, treatment for disease and calving difficulty score. Heifers in Q1 produced 1992 kg (95% CI=1858, 2127 kg) of milk when controlling for all other variables. Relative to heifers in Q1, heifers in Q2, Q3 and Q4 produced 130 kg (95% CI=313, -52 kg; P=0·45), 285 kg (95% CI=474, 96 kg; P=0·004) and 169 kg (95% CI=395, -57 kg; P=0.14) less milk, respectively. In conclusion, efficacy of alveolar-arterial oxygen transfer was associated with milk yield in dairy heifers on one farm at moderate altitude.

Myosin heavy chain 15 is associated with bovine pulmonary arterial pressure.

Bovine pulmonary hypertension, brisket disease, causes significant morbidity and mortality at elevations above 2,000 m. Mean pulmonary arterial pressure (mPAP) is moderately heritable, with inheritance estimated to lie within a few major genes. Invasive mPAP measurement is currently the only tool available to identify cattle at risk of hypoxia-induced pulmonary hypertension. A genetic test could allow selection of cattle suitable for high altitude without the need for invasive testing. In this study we evaluated three candidate genes (myosin heavy chain 15 [MYH15], NADH dehydrogenase flavoprotein 2, and FK binding protein 1A) for association with mPAP in 166 yearling Angus bulls grazing at 2,182 m. The T allele (rs29016420) of MYH15 was linked to lower mPAP in a dominant manner (CC 47.2 ± 1.6 mmHg [mean ± standard error of the mean]; CT/TT 42.8 ± 0.7 mmHg; P = 0.02). The proportions of cattle with MYH15 CC, CT, and TT genotypes were 55%, 41%, and 4%, respectively. Given the high frequency of the deleterious allele, it is likely that the relative contribution of MYH15 polymorphisms to pulmonary hypertension is small, supporting previous predictions that the disease is polygenic. We evaluated allelic frequency of MYH15 in the Himalayan yak (Bos grunniens), a closely related species adapted to high altitude, and found 100% prevalence of T allele homozygosity. In summary, we identified a polymorphism in MYH15 significantly associated with mPAP. This finding may aid selection of cattle suitable for high altitude and contribute to understanding human hypoxia-induced pulmonary hypertension.

An investigation into beef calf mortality on five high-altitude ranches that selected sires with low pulmonary arterial pressures for over 20 years.

Producer reports from ranches over 2,438 meters in southwest Colorado suggest that the mortality of preweaned beef calves may be substantially higher than the national average despite the selection of low pulmonary pressure herd sires for over 20 years. Diagnostic investigations of this death loss problem have been limited due to the extensive mountainous terrain over which these calves are grazed with their dams. The objective of the current study was to determine the causes of calf mortality on 5 high-altitude ranches in Colorado that have been selectively breeding sires with low pulmonary pressure (<45 mmHg) for over 20 years. Calves were followed from branding (6 weeks of age) in the spring to weaning in the fall (7 months of age). Clinical signs were recorded, and blood samples were taken from sick calves. Postmortem examinations were performed, and select tissue samples were submitted for aerobic culture and/or histopathology. On the principal study ranch, 9.6% (59/612) of the calves that were branded in the spring either died or were presumed dead by weaning in the fall. In total, 28 necropsies were performed: 14 calves (50%) had lesions consistent with pulmonary hypertension and right-sided heart failure, and 14 calves (50%) died from bronchopneumonia. Remodeling of the pulmonary arterial system, indicative of pulmonary hypertension, was evident in the former and to varying degrees in the latter. There is a need to better characterize the additional risk factors that complicate pulmonary arterial pressure testing of herd sires as a strategy to control pulmonary hypertension.

Onchocerca armillata contains the endosymbiotic bacterium Wolbachia and elicits a limited inflammatory response.

Human onchocerciasis, also known as River Blindness, is a debilitating disease caused by the filarial nematode Onchocerca volvulus. Many, but not all, filarial nematodes carry within their tissues endosymbiotic, Rickettsia-like bacteria of the genus Wolbachia. Onchocerca spp. infections in cattle offer the most relevant, analogous host-parasite model system. West African cattle are commonly co-infected with four Onchocerca spp.; two of these are Wolbachia-positive (Onchocerca gutturosa and Onchocerca ochengi), and the remainder are of unknown Wolbachia status (Onchocerca dukei and Onchocerca armillata). Previous studies have suggested that worm survival is dependent on this bacterium. O. armillata, an abundant parasite of African cattle that has received little attention, is a primitive species that may lack Wolbachia. The objectives of this study were to determine if O. armillata carries Wolbachia and to provide preliminary descriptions of the host inflammatory cell environment around the adult worms. The findings may support or refute the hypothesis that a prime contribution of Wolbachia is to permit long-term survival and reproduction of certain Onchocerca spp. (including O. volvulus in humans). O. armillata adult worms were found in the aorta of 90.7% of cattle (n=54) slaughtered at an abattoir in Ngaoundéré, Adamawa Region, Cameroon. The presence of Wolbachia in O. armillata was confirmed by a specific anti-Wolbachia surface protein antibody detected using a peroxidase conjugate (immunohistochemistry) and PCR for detection of Wolbachia-specific sequences within DNA extracts from frozen worms. Tissue sections stained with haematoxylin and eosin showed the host cell response to be dominated by macrophages and fibroblasts. This is unusual compared with nodule-dwelling Wolbachia-positive Onchocerca spp., where the host response is typically characterised by granulocytes, and suggests that the mechanisms for worm survival employed by this species (which is probably motile) may differ.