Pork CRC Makes Progress in Boosting Sow Lifetime Productivity

by 5m Editor
3 November 2011, at 12:00am

A review of recent research carried out by Pork CRC into improving sow productivity. Among the findings is that sow productive lifetime is maximised when gilts and sows have a certain amount of body protein mass and a minimum level of body fatness.

Subprogramme 2D, ‘Improving sow reproduction and longevity’, led by Rob Smits of Rivalea, arguably had the most new and innovative research projects in the Pork CRC, with 33 projects commissioned since 2005-06, with some continuing into the new CRC.

The main research areas were:

  • improving sow longevity and lifetime sow performance
  • investigating the cause and impact of differences between gilt and sow progeny
  • investigating the potential for a new approach to breeding management through inducing lactational oestrus, and
  • alleviating the costly impacts of summer/seasonal infertility

Professor Frank Dunshea, Manager, Pork CRC Programme Two: ‘Improving herd feed conversion efficiency’.

Project 2D-104, ‘Management strategies to maximise sow longevity and lifetime performance’, a completed collaboration between CHM, SARDI and Rivalea, has considerably improved understanding of what contributes to poor longevity and why certain sows are at risk of early exit from the breeding herd. Modern sow genotypes are larger and leaner and we have now established that sows of a certain size and body condition are more likely to be removed from the herd for low productivity and increased mortality.

The project found that mating weight of gilts and parity 1 sows are well correlated to body protein mass and body fatness increases with parity.

Further, in modern genotypes rate of body fat deposition proceeds with parity at only a slighter higher rate than protein deposition.

Therefore, feeding sows to increase fatness and body condition mostly increases sow size, without considerably increasing P2 backfat.

Sow productive lifetime is maximised when gilts and sows have a certain amount of body protein mass and a minimum level of body fatness.

Exceeding or failing to achieve these thresholds causes productivity and longevity to decline.

The project provides the information and predictive equations for producers to monitor their own genotypes and identify sows at risk of culling.

Adjusting lactational demands on the sow is another outcome resulting in improvements in litter size and sow productivity.

As the industry moves further into group housing and new lactation-mating management systems, 2D-104 will help determine how sows are appropriately fed and managed.

Project 2D-120 and 2D-129, ‘Inducing ovulation during lactation’, examined the potential of a system for inducing oestrus in lactation, allowing the flexibility of independent weaning and mating.

The outcomes have confirmed that oestrus can be induced in more than 90 per cent of sows while lactating and that, when mated, their reproductive performance compares favourably with control sows weaned and mated at first oestrus post-weaning.

A series of experiments examined the effect of litter separation, boar contact and hormone use to promote follicle growth. Litter separation improved induction success, but can negatively impact litter weight gain, so experiments were conducted to determine how litter separation could be reduced. Interestingly, a large proportion of sows had a spontaneous oestrus without litter separation and boar stimulation.

Projects 2D-107 to 2D-110, ‘Addressing summer/ seasonal infertility’, investigated seasonal infertility, which remains a complex and costly limitation to consistent pig production flows.

University of Sydney and University of Adelaide research showed that poor oocyte quality and insufficient progesterone support for the conceptus was associated with summer-mated sows.

Nutritional strategies to improve oocyte quality and embryo survival have included betaine and omega-3 fatty acids.

Energy responses at the ovarian-utero level have also been investigated for effect on progesterone, embryo survival and litter size and conception rate outcomes.

A producers’ guide, Seasonal Infertility in Pigs, was published in December 2010 to describe how best to manage gilts and sows during summer and autumn to reduce infertility.

During the funding period, the impact of the breeding herd on HFC has been estimated at about 0.2-0.25 units or 16-20c/kg COP when improvements to breeder herd productivity lead to an attainable replacement rate of 40 per cent.

November 2011