Genesis, design and methods of the Beef CRC Maternal Productivity Project

Abstract

Australian seedstock cattle breeders have expressed concerns that while there has been genetic improvement in feedlot and abattoir performance of cows, it could have led to a decline in maternal productivity, especially under variable nutritional conditions. This paper describes a substantial project with two components designed to address these issues. The first sub-project was to monitor bodyweight and composition of 7760 young Angus and Hereford cows as they experience variable physiological states (pregnancy and lactation) and seasons. This was conducted on large numbers in seedstock herds. The second sub-project was to monitor more regularly bodyweight, body composition, and calf rearing performance of 500 Angus cows that are genetically divergent for either fat or residual feed intake at two research centres. This also included two levels of nutrition and recording of weekly feed intake of small groups of cows for at least three parities to allow reporting of genotype × nutrition effects on maternal productivity and efficiency. Results from the project are reported in a series of papers with each one having a defined focus.

Abstracts from the Proceedings of the 34th Biennial Conference of the Australian Association of Animal Sciences

“…At the start of the Beef CRC Maternal Productivity Project, commercial beef breeders raised concerns that genetic selection programs were focusing too heavily on feedlot and carcass traits with a negative weighting on fat depth to increase lean meat yield, and cows were becoming too lean as a result. There was concern that this would lead to a decline in maternal productivity, especially during times of feed shortage (Lee et al 2018;Pitchford et al 2018). Thus, the question to be addressed in this paper is how much genetic variation is there in cow body composition independent of genetic variation in yearling composition?…”

A regional-scale assessment of nutritional-system strategies for abatement of enteric methane from grazing livestock

“…Research for determining an optimal rate of post-weaning growth to enable early joining and maximising lifetime breeding productivity in cattle has shown that results from more recent work (Le Cozler et al 2008) diverge from those of early research (Short and Bellows 1971). This suggests that with genetic progress, the optimal nutritional strategies to achieve early joining may have changed and need re-assessment (Pitchford et al 2018;Walmsley et al 2018).…”

A large proportion of genetic variation in cow and ewe body composition is independent of yearling composition

“…At the start of the Beef CRC Maternal Productivity Project, commercial beef breeders raised concerns that genetic selection programs were focusing too heavily on feedlot and carcass traits, with a negative weighting on fat depth to increase lean meat yield, and cows were becoming too lean as a result. There was concern that this would lead to a decline in maternal productivity, especially during times of feed shortage (Lee et al 2018;Pitchford et al 2018a). Thus, the question to be addressed in this paper is how much genetic variation is there in cow body composition independent of genetic variation in yearling composition?…”