Identifying and exploring new approaches to optimise the weaning of cattle youngstock

Abstract

Current methods take a generalised, indirect approach to weaning the calf from cow. Novel optimised weaning methods for youngstock cattle are presented in this thesis by revealing new knowledge pertaining to rumination development and other critical behaviours at an individual animal level through advanced technologies. Previous work on calf development and weaning strategies are reviewed in Chapter 2, which highlights the variability, limitations, and gaps of current weaning methods. The first step towards filling these gaps is taken in Chapter 3 where an accelerometer-based ear-tag technology is evaluated as to its accuracy for automatically recording calf rumination and suckling behaviours. High accuracy between the visual behaviour durations and the ear tag output was found. This allows for the variability and development of calf rumination and suckling behaviour to be determined in Chapter 4 alongside the impact of weaning on rumination duration, intake, and weight gain. While exploring a novel dairy cow-calf system, Chapter 5 reveals dairy calf growth to be able to match that of beef systems when reared on the cow for over 100 days on pasture, while also highlighting the negative impact of abrupt separation on the cow in Chapter 6. To address this, Chapter 7 then compares the impact of this abrupt separation with fenceline separation on behaviour, cortisol levels and weight gain in calves and cows, over a longer duration than preceding work enabled by the ear tag technology. And finally, the thesis culminates in Chapter 7 where a new process of weaning with cows and calves separated by fenceline for 3 days before full separation is recommended for industry to optimise both cow and calf performance whilst minimising stress. This progression of work highlights the opportunity for industry to adopt new weaning methods for improved production and welfare but also reveals the opportunities to expand on this novel research to further exploit the variability that exists between animals.