Relationship of pulmonary arterial pressure and terrain use of Angus cows grazing high-altitude foothill rangelands

Abstract

Pulmonary arterial pressure (PAP) score is used as an indicator trait for risk of 20 hypoxia-induced pulmonary hypertension, which is commonly termed high altitude disease and 21 observed in cattle grazing at altitude ≥ 1500 m. We hypothesized that cows with higher PAP 22 score would avoid using high elevations, steep slopes and areas far from water while grazing 23 foothill rangeland. During 2013 and 2014, forty-one mature Angus cows from a breeding 24 population of cattle selected for tolerance to high altitude were tracked with global positioning 25 system (GPS) collars for 27 and 17 days, respectively. These cows grazed a 1210 ha foothill 26 rangeland pasture with a vertical relief of 2150 to 2411 m. Pulmonary arterial pressure was 27 measured for each animal at 1 year of age (yearling PAP; 38.2 mm Hg ± 5.1 SD mm Hg) and 28 before tracking (mature PAP; 42.6 mm Hg ± 3.7 SD). Yearling PAP score was not correlated 29 with the mature PAP score (r = 0.23, P = 0.15). Terrain use varied among individual tracked 30 cows, and the range among cows within the same pasture was 59 m (2204 m ± 15 SD) for 31 average elevation use, 4.7 percentage points (8.9% ± 0.2 SD) for average slope use and 247 m 32 (446 m ± 77 SD) for average distance from water. No correlation was detected between mature 33 PAP scores and terrain use metrics (mean elevation, slope and distance from water of tracked 34 locations; r = -0.16, 0.24, 0.25; P > 0.10). Similarly, no correlation was detected (P > 0.10) 35between yearling PAP score and terrain use metrics. Yearling and mature PAP scores were not 36 correlated (P > 0.50) to indices of terrain use that combined elevation and slope use (rough 37 index) and elevation, slope and distance from water (rolling index). Yearling PAP and mature 38 PAP were not useful predictors (P > 0.10) of terrain use in multiple regression analyses. Angus 39 cows in this study were apparently adapted to high elevations and PAP score had little, if any, 40 relationship with their metrics of grazing distribution of foothill rangeland. In situations where 41 elevation was higher, terrain was more rugged or cattle were not adapted, results may differ from 42 those observed in this study. 43 44

Grazing Behaviours of four Nigerian Breeds of Cattle in Awka, Southeast Nigeria

“…Furthermore a significant difference among Muturu and Sokoto gudali on the total grazing record which contradict the findings of this study has been reported [24]. Muturu is highly adapted breed in southern part of Nigerian while Sokoto gudali in northern part of Nigeria, his experiment was undertaken in south east of the country recalling that grazing behavior can be acquired [25] and has been repeatedly reported to be affected by geographical condition.…”

Factors Affecting Site Use Preference of Grazing Cattle Studied from 2000 to 2020 through GPS Tracking: A Review

“…Cows differing in their phenotypical habit to use hilly terrains graze different parts of the same pasture; “hill climbers” use rougher terrain and begin travelling to water about one hour later than cows previously classified as “bottom dwellers” [ 88 ], showing the degree of asynchrony in the motivation to eat or drink of different individuals [ 37 ]. However, other phenotypical traits (e.g., differences in pulmonary arterial pressure) between “hill climbers” or “bottom dwellers”, are not useful predictors of terrain preference within Angus cows adapted to high elevations [ 89 ].…”