More milk for more pigs

The specific theme of Dr Farmer’s paper dealth with ‘Maximising mammary development to increase sow milk yield’. The background to this target is the fact that, while advances in genetics and management have facilitated larger litters, the sow’s ability to feed those larger litters adequately in the critical early weeks has not improved to the extent necessary. Put simply, the sow is not producing enough milk to sustain maximal piglet growth. Hyper prolificity, as Dr Farmer explained, is a relatively new problem. As the litter size has increased, the amount of milk ingested per piglet has decreased. As confirmed by the Canadian researcher, the number of secretory cells present in the sow’s mammary tissue at the onset of lactation is the main factor limiting milk yield.

Mammary development

This is clearly an entire research field. There is the existing knowledge on mammary development to be assessed with critical questions to be answered around when mammary development takes place and the impact of hormones on that development. With that knowledge, influential factors can be identified including pre-puberty and late-gestation management. Body condition and mammary development in the late-gestation period must be managed optimally to increase milk-production potential. The IPHS conference attendees were informed that there are three main timelines when rapid mammary accretion can be achieved. These include the prepubertal period from 90 days onwards, the last third of gestation and during actual lactation. It is in one or the other or all of these three specifically identified periods that it is possible to stimulate increased milk production. Dietary and supplementation management are not new. Dr Farmer reached back to research carried out in 1945 to confirm outcomes on the ingestion of barley ergot for the last 25 to 87 days of pregnancy in sows. This research essentially provided evidence of what does not encourage udder development of milk secretion. It was not until the 1970s that research confirmed that the inclusion of barley ergot depresses prolactin, the critical hormone for mammary growth and milk production during pregnancy and after giving birth. This breakthrough then facilitated the development of management and feed formulation technologies to increase prolactin, with favourable outcomes in terms of early lactation milk yield and significantly improved piglet weight – up to 21 per cent during lactation. Commercialising this research was then targeted and successfully introduced.

Feeding for milk production

Manipulation of nutrition at critical periods in the sow-feed management was further highlighted by the Canadian researcher, with specific guidelines delivered. Returning to the aim of improving mammary development, Dr Farmer spoke about the use of natural stimulants, including a milk thistle extract, silymarin, as a prolactinemic agent. It had been shown to be efficacious in raising prolactin in rats as well as milk yield in humans and cows. However, fed to sows, there was evidence of some increase in prolactin but not on a large enough scale to improve mammary development or milk yield. In what is clearly a complex field of research, Dr Farmer outlined various approaches in terms of nutrition management and supplementation with the ultimate aim of increasing milk yield at that critical early life of the suckling piglets. Her concluding message was enlightening – that there is still much to be learned. The data from this ongoing research is provided in the Canadian researcher’s paper available on the IPHS website.