Data from: A comprehensive study of respiration rates in dairy cattle

Respiration rate (RR) is often used to assess health and heat stress in
cattle, influencing decisions that affect their welfare (e.g., medical
treatment, cooling). Despite its importance, systematic information on how
RR responds to various intrinsic and extrinsic factors is limited. This
study recorded RR and behavior of 406 female Holstein and Jersey cattle
(newborn to sixth lactation cows) in California over a year, aiming to: 1)
describe RR across different life stages (calves, heifers, lactating, and
dry cows), 2) evaluate how different weather or thermal load indexes
predict RR using linear regression and mixed models, and 3) assess the
effects of individual characteristics (life stage, breed, milk production,
lactation state) and behavior (posture, location) on RR in a Mediterranean
climate. A total of 11,210 RR and behavior records were obtained over 39 d
between October 2016 and August 2017. Each record was paired with
individual characteristics and 25 different weather parameters within 5
min of collection. Data analysis utilized descriptive statistics, mixed
models, linear and multinomial logistic regressions. Across all life
stages, RR ranged from 16 to 185 breaths/min, with first and third
quartiles at 37 and 59 breaths/min, respectively. The likelihood of upper
normal RR values (30 to 50 breaths/min, according to some textbooks) was
highest when air temperatures (AT) were below 20-25°C, depending on the
life stage. During observations, AT ranged from 1.8 to 43.9°C and was the
sole most reliable RR predictor, accounting for 35% of the observed
variation. While most individual characteristics and behaviors influenced
RR, the biological significance was sometimes unclear. Calves showed the
highest RR increase (+17 breaths/min per 10°C increase in AT), while dry
cows had the lowest (+11 breaths/min). Changes for heifers and lactating
cows were 13 and 14 breaths/min per 10°C increase in AT, respectively. We
suspect differences in cooling provision and metabolic rates across
categories drove these results. In general, Jersey cattle had higher RR
than Holsteins, (~3 breaths/min every 10°C), except in calves. RR were the
lowest when heifers, lactating, and dry animals were near the feed bunk,
likely due to soakers' provision for mature cattle. RR averaged 52
and 49 ± 3 breaths/min for lying down and standing postures, respectively,
with <1 breath/min change per 10°C increase in AT. For lactating
cows, RR increased by ~2 breaths/min for every 10 kg of milk produced but
reduced by ~1 breath/min for every 50 d of pregnancy. There was no
relationship between RR and DIM or lactation number. Our study
systematically collected RR data from a relatively large number of dairy
cattle across different life stages and weather conditions, suggesting
that current textbook RR thresholds may underestimate upper values for
cattle and demonstrating that AT was the most reliable predictor of RR
changes in a Mediterranean climate. RR varied with life stage, breed,
posture, location, milk yield, and gestation length, with more pronounced
changes in calves, suggesting a need for further research to understand
these variations and their welfare implications.