Pork CRC Subprogram Leader, Professor Paul Hemsworth of the Animal Welfare Science Centre (AWSC), University of Melbourne, said domestic pigs, just like their wild relatives, needed to establish a social order or hierarchy and this needed to be done quickly when sows were first mixed.
“Sows need adequate space to avoid other sows and research has shown that space is more important than group size when mixing sows.
Producers at the workshops generally agreed that providing plenty of feed, including perhaps multiple drops per day if floor feeding, was very important, especially when sows were first mixed in groups.
All feeding arrangements, including electronic sow feeding systems (ESFs), where sows are trained and full or shoulder stall feeding, had advantages and disadvantages.
Producers should, for example, ensure sufficient ESFs for the number of sows in the pen to minimise aggression during entry to the ESF.
Dr Jean Loup Rault, a colleague of Professor Hemsworth at AWSC, addressed the workshops, recommending that, in order to limit unwelcome aggression between sows mixed at weaning, producers should consider using feeding stalls, distinct mating stalls and make efforts to limit sexual interaction by dominant sows over submissive sows.
Chris Richards and Associates veterinarian, Dr Bernie Gleeson, warned of unintended consequences, saying that nothing happened in isolation and this was particularly the case in group housing.
Producers needed to be aware of potential hazards such as mycotoxins in straw bedding, overweight sows, especially when floor feeding where dominant sows may eat more than submissive sows and the strategic placement of self feeders.
Robust producer panel discussions were held at the Toowoomba and Melbourne workshops, with most agreeing that the transition to group sow housing, albeit challenging, was working well and that there was no one size fits all solution.
Most agreed that the positive perception of improved sow welfare was apparent.
A very informative manual, titled ‘Mixing Sows – How To Maximise Welfare’, was launched at the workshops and made available to producers. It can be viewed and/or downloaded from the Pork CRC website at http://porkcrc.com.au/
Edited by Pork CRC Program One Leader, Dr Ray King, it is very comprehensive, outlining the latest research on group housing sows and strategies for mixing sows post weaning or post insemination.
Some key take-home messages in the manual are:
- Current Australian research indicates that the minimum space allowance for group housed sows is likely to be somewhere between 1.8 and 2.4 m2 per sow.
- Sows adapt quickly to mixing and may adapt to reduced space during later stages of pregnancy.
- Physical and visual barriers within pens of large groups of sows allow sows to avoid each other and escape aggressive sows.
- Sows should receive average daily intakes that maintain targeted body condition.
- Higher feeding levels immediately after mixing and through to day 28 of gestation will minimise the risk of less dominant sows receiving less nutrition, as well as reduce aggression.
- Feed should be spread widely to allow greater access by timid sows, while multiple feed drops, every 30 to 60 minutes, may reduce aggression at feeding.
- Dynamic groups should not experience more welfare issues than static groups, provided only a small proportion of sows enter and are removed from the group at each change.
- Keep the majority of sows in the same group from one pregnancy to the next and try to match sows into groups, based on parity and size.
Source: AASV