Abstract
Dystocia is a leading cause of calf mortality, yet there is little available information quantifying the duration and forces applied to assisted deliveries. Objectives of this study were to: (1) develop a method to measure the magnitude and duration of various forces applied to a calf during calving assistance, and (2) quantify the forces applied to beef calves during manual or mechanical calving assistance. Twenty-five primiparous dams requiring calving assistance were enrolled. Calvings were assisted by manual (1 or 2 people pulling) or mechanical (calf extractor) delivery. A set of modified obstetric chains with integrated force measuring devices (Calving Assistance Force Logger; CAF-Log) were applied to the calf for delivery. The CAF-Log system was calibrated using known masses ranging from 25 to 200 kg in increasing increments of 25 kg. Duration of the assisted delivery and force parameters (peak force applied to one leg, peak force applied to both legs, cumulative force, and maximum jerk force) were described and assessed for their associations with method of delivery and ranch. Median duration was 112.6 s (IQR: 88.4–149.7) for manual and 312.6 s (IQR: 221.6–462.3) for mechanical deliveries. Mean peak force applied to one leg was 56.9 kg (SD: 22.9) for manual and 126.8 kg (SD: 48.2) for mechanical deliveries. Mean peak force applied to both legs was 95.4 kg (SD: 34.1) for manual and 188.6 kg (SD: 83.9) for mechanical deliveries. Median cumulative force was 178.3 kg min (IQR: 21.1–38.8) for manual and 380.6 kg min (IQR: 252.1–581.3) for mechanical deliveries. The maximum jerk force for manual deliveries was 36.6 kg/s (IQR: 21.1–38.8) and 77.2 kg/s (IQR: 60.9–97.1) for mechanical deliveries. An interaction occurred between ranch and method of delivery for peak force applied to one leg, peak force applied to both legs, and cumulative force. The CAF-Log system demonstrated that significantly greater forces were applied to mechanically delivered calves compared to manually delivered calves and could be used in future studies to investigate forces applied to a calf during calving assistance and their impacts on cow and calf well-being.
Highlights
Calving difficulty negatively impacts overall herd productivity due to increased calf morbidity and mortality [1,2,3], reduced subsequent fertility and production in cows [4,5,6], and increased labor inputs by ranch personnel [7]
Obstetrical chains were modified to measure the amount of force placed on manually and mechanically delivered calves
The Calf Assistance Force Logger (CAF-Log) system developed for this study successfully enabled measurement of various force parameters applied to calves during both manual and mechanical assisted deliveries under field conditions
Summary
Calving difficulty negatively impacts overall herd productivity due to increased calf morbidity and mortality [1,2,3], reduced subsequent fertility and production in cows [4,5,6], and increased labor inputs by ranch personnel [7]. The incidence of fetal trauma [9,10,11], broken bones and dislocated joints [12], and hypoxia and mixed respiratory and metabolic acidosis [13,14,15,16] increase with the severity of calving difficulty, and these directly impacts the vigor, transfer of passive immunity, health, and performance of the calf [11, 16,17,18]. A device that can digitally measure various types of forces applied during live calving assistance has not been described and may be useful to objectively classify calving difficulty when assessing the impacts of calving difficulty on cow and calf health. The objectives of this study were to: [1] develop a method to measure the magnitude and duration of various forces applied to a calf during calving assistance, and [2] quantify the forces applied to beef calves during manual or mechanical calving assistance
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