Editor’s note: In this first of a two-part series, the importance of achieving high weaning weights and how it leads to higher market weights is discussed. In Part II, we look at areas of management that can have an influence on feed intake and pig performance.
Small adjustments in lactating sow and nursery systems can have dramatic impacts on lifetime performance.
It is well documented that weaning age and weaning weight have large impacts on lifetime performance. (Main, et al 2004) showed in two trials the importance of weaning age on wean to finish performance, see Table 1. These results showed the benefit of increasing weaning age not only on pork throughput in the system but also on a greater income per pig.
Weaning weight is also important in improving post-weaning performance. A commercial evaluation in Canada showed that increasing weaning weight from 3.8 kg to 6 kg improved the 42-day post-weaning performance by 4.2 kg or the equivalent of 45 g/day for a 1 kg improvement in weaning weight. This is supported by work conducted by the Prairie Swine Centre which showed that for every 1 kg extra in weaning weight there was an improvement in ADG by 40 g/day through the nursery..
Not only is the benefit seen through the nursery but also through the finishing units reported that 1 kg extra at weaning resulted in 4.2 kg at 20 weeks of age.
Achieving high weaning weights
These results show that as we know, improving weaning age and weight improves subsequent performance. Attention to the lactating sow is important to ensure that high weaning weights for age are achieved. Although weaning weight and age are important, two studies out of Leeds University by the Helen Miller group showed the importance of early post-weaning growth on subsequent pig performance..
In the first study, there was a strong correlation between both weaning weight and growth rate in week one on subsequent performance post-weaning. Their influence is very similar and their impact is additive. Day 20 live weight = 3.73 + 1.25 weaning LW + 8.92 ADG in week 1 (r2 0.798, P < 0.001)
As both weaning weight and week one post-weaning average daily gain had equal effect on the day 20 weight, then management practices that promote high feed intake in that first week after weaning should be given as much focus as maximizing weaning weight..
The second study at Leeds University (Isley, et al 2001) conducted a similar study but investigated birth weight, weaning weight and 20-day growth rate on lifetime performance and showed the best predictor of weight at slaughter was day 20 post-wean average daily gain > weaning weight > birth weight and that weaning weight with day 20 post-weaning ADG were the best predictors for weight at slaughter.
This is supported by research that showed the importance of one week post-weaning growth rate on days to market with pigs doing greater than 115 g/day in week one getting to market 10 days quicker than pigs doing less than 115 g/day (Pollman 1993).
Improving weight at market
In the Leeds study it was possible to determine what was required at birth weight, weaning weight or 20-day growth rate to improve weight at market by 1 kg.
Looking at the parameters of change required to gain the extra 1 kg at slaughter, both the 20-day ADG and weaning weight are achievable (5% improvement on average performance) through management and nutrition while increasing birthweight by 10% is more difficult to achieve. It must be remembered that it has been reported in numerous trials that extra gain out of the nursery results in extra gain at finish with 1 kg in the nursery translating to an extra 2 to 4 kg at slaughter.
On average, the industry would equate an extra 1 kg out of the nursery to 2.5 kg at slaughter or 2.5 to 3.5 days saving to get to the same slaughter weight. Therefore, nursery management can improve post-weaning performance if we can achieve just a 5% improvement in that first 3 weeks post-weaning, we can deliver an extra 1 kg of live weight to the producer at market.
Thus, this shows that if we can increase feed intake in the 3 weeks post-weaning and thereby gain, then pigs should get to slaughter quicker or produce more pork in the same period, both providing returns to the pig producer.
It is well-known that dry matter intake drops immediately post-weaning as the pig comes off the sow’s milk onto a dry feed in a strange environment. This is one common stress that reduces feed intake that needs to be overcome but this can be complicated as feed intakes vary dramatically from unit to unit depending on other stresses in the system. This is because of appetite being sensitive to all type of stress, discomfort and disease.
Nucleus units with few stresses, for example, have higher feed intakes while units with many stresses (disease and poor management) have lower intakes.
If we are in the situation of low feed intake and low nursery performance because of disease and management, can we change it for the better?
By improving feed intake it has been shown that there was a positive relationship between increasing feed intake, improving gut integrity (villous height) and improving post-weaning gain - all factors we want to achieve.
A practical example of management improving performance was when five commercial farms all suffering from E. coli scour and mortality had pigs weaned into either their existing production system or into a research and development (R&D) facility with excellent management and an all in, all out policy.
All feed fed to the pigs in the commercial farms and those in the R&D facility was the same, thereby removing any feed factor on the evaluation as all pigs were fed the same feed program.
The results in Table 2 were achieved by improving the environment and management on the pig. In the second part of this series, we will looks at some of these areas and their effects.