Agewean
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Research partners: University of Newcastle,ADAS, BIOSS, Harper Adams University College, BPEX
and SAC
Sponsors: Defra
Project duration: 2003-2007
Final report - download here
Summary:
The objectives of the work were:
• To determine whether increasing weaning age gives significant health and performance benefits
when all dietary AGPs are removed and heavy metals (zinc, copper) are reduced
• To determine the implications for production economics and environmental impact at a whole
systems level for different weaning ages
Weaning ages of 4, 6 and 8 weeks have been compared in multi-site trials involving nearly 600 sows
and representing both outdoor and indoor production. Key evaluations included lifetime sow
productivity over 4 parities, performance of piglets after weaning at these different ages, and monitoring
of sub-samples (25%) of the progeny for growth performance from weaning to slaughter. Trials have
been completed on schedule with the following major conclusions.
• There were significant benefits from later weaning in terms of piglet performance during the
immediate post-weaning period. These were reflected in later weaned piglets having significantly
better feed intakes and daily liveweight gains, and a more favourable gut microflora (assessed by
faecal lactobacilli:coliform ratio). Pigs weaned at later ages were also significantly less likely to be
removed from trial or die during the weaning to slaughter period. However, when progeny
performance was considered over the full period from birth to slaughter, no overall benefits of
later weaning for survival, health or growth rate were seen.
In terms of sow productivity, there was a significant production penalty to be paid by later weaning.
Sows weaned at 8 weeks of age produced the equivalent of 4 fewer piglets per year than sows weaned
at 4 weeks of age.
• The feed cost per weaner up to the point of weaning was obviously greater for the later
weaning ages but, despite the different qualities and costs of diets used in the post-weaning
phase, the overall lifetime feed cost per kg progeny live-weight gain (including all sow feed
inputs) did not differ significantly between treatments.
• Modelling of the overall system economics to take account of pig performance and resource
requirements in the form of both fixed and variable costs, indicated a lower production cost for
the 4-week weaning system in comparison with the 6- or 8-week weaning system (by
approximately 3 p/kg carcase weight in July 2007, or 2.8%).
• Nutrient budget calculations, based on overall feed inputs (eaten plus wastage) and diet analyses
for each treatment, indicated that feed nitrogen and phosphorus inputs per kg pig produced
were significantly greater for the later weaning ages, suggesting the potential for greater
environmental impact. Pigs in the 8-week weaning system received over 10g more phosphorus
and over 500g more nitrogen in feed inputs to reach slaughter weight when compared to the
4-week weaning system.
• Under current UK conditions, and with appropriate nutrition and management, later weaning of
piglets at 6 or 8 weeks of age therefore appears to offer no significant benefits for health or
performance of the progeny which outweigh the reduction in sow output when compared to
the current industry norm of 4 week weaning.
