Silage solves straw issues for pigs

An extensive experiment conducted by Australia’s largest pork producer, SunPork Group, has confirmed that silage has an important role to play in enriching the environment of pigs. Straw is often used as the ‘gold standard’ for enrichment but it is the least-preferred option because of the risks it poses in terms of biosecurity, fire, mycotoxins and effluent management.

While silage is not traditionally associated as a feed ingredient in pork production, the SunPork Group has recently assessed its use as an ‘enrichment’ material as part of their commitment to leading animal care and sustainability. ‘Enrichment’ aims to provide indoor-housed pigs with a stimulating environment that allows natural behaviour, such as rooting, foraging, and nesting.

Common methods of enrichment include the provision of straw, forage, wood shavings, shredded paper or toys, such as ropes, chains or balls.

The recent experiment, which involved more than 700 sows, examined the impact of providing silage to sows during the seven-day interval between weaning and mating on animal welfare and reproductive performance. SunPork Research Officer, Dr Lauren Staveley, says weaning is arguably the highest stress period for a sow. “She is separated from her piglets, she’s producing milk, she’s mixing with unfamiliar sows in a new environment, she’s consuming a new diet and she’s coming into heat – it’s all happening,” Lauren says.

“We wean the sows three to four weeks after giving birth and put them on a special weaning sow diet for seven days until mating.

Providing the sow with enrichment material in the environment is a simple way to reduce competition, fighting and injury during this potentially stressful period. Increased intake of glucose and roughage between weaning and mating has been shown to also have positive effects on reproductive
performance,” Lauren states.

Freshly weaned sows were moved into groups of eight animals per pen in the mating shed and allocated to treatments, ensuring even distribution of parity and body condition. The Control group was offered a standard diet (13.4 MJ DE/kg) ad libitum for seven days post weaning. The Treatment group was offered the same diet and 3 kg/sow/day (0.33–0.35 DM equivalent) of export-quality corn silage, placed on the floor of the pen for the seven days following weaning.

Body condition and injury scores were measured for the seven-day experimental period. Blood and faecal samples were also collected from each group at entry and exit to monitor markers of metabolism and stress. Cameras were installed over every pen to determine welfare using the sows’ ‘startle’ score.

A comprehensive set of reproductive data, including the weaning-to-mating interval, conception rate, farrowing rate, litter size farrowed, pre weaning piglet mortality and litter size weaned was also collected.

“We’re still analysing the results but at the moment, we can say that the provision of silage to sows at weaning minimised the reaction to an adverse stimulus (Figure 1), which would suggest they are less reactive and so more comfortable. This is an important welfare finding” Lauren says.

However, there were no difference in injury scores. Lauren states “The injury scores in both groups were very low, which we attribute to the fact that we’ve eliminated close confinement from our production systems, so the sows are used to group environments.”

The analyses of the reproductive measures are still being conducted, but to date don’t indicate any treatment effects.

“Silage addresses all of the issues that straw poses for us. We are now looking at using silage at different stages of the production cycle, such as pre-farrowing,” says Dr Kate Plush, Science Technology and Adoption Manager at Sunpork.

“We are also quite happy with the practicality of it. Our farm staff were very supportive about the experiment and commented on the ease of use including easy to handle, the pens were much cleaner, the drains weren’t blocking and there was less slippage, even with regular pen hosing”, Kate commented.

The trial was funded by APRIL in conjunction with Sunpork Group and Lallemand Animal Nutrition.

SunPork is Australia’s largest pork integrator, accounting for about 20% of the country’s pork production. Its business spans across the pork value chain.