We are still reviewing some actions from the production point of view that we can carry out in order to improve the conversion index.
1. Carry out a correct handling of the loading of the pigs to be taken to the abattoir. If the animals fast for some 12 hours before their loading onto the lorry we will reduce the feed consumption and we will improve the conditions of the transport to the abattoir. Nevertheless, adding up the transport and the waiting time at the abattoir we should not exceed 24 hours of fasting in total (Steward, 2008).
During the periods of fasting-refeeding the animals keep consuming nutrients for their maintenance, so we must avoid that this happens (Brumm, 2008). In order not to affect the fasting of the animals that have to be loaded onto the lorry nor the growth of the pigs that will remain for more days in the farm it is interesting to have special waiting pens. The alternative is to mark, during the previous day, the pigs that will be loaded onto the lorry and evaluate, in each pen, if the majority of the pigs are the ones to be loaded or the ones that will remain in the farm, in order to make the decision whereas all the animals in the pen will fast or if we will separate them according to the moment in which they will be loaded onto the lorry.
2. Check the slaughter weight. High slaughter weights cause the CI to increase. When measured, the effect of the slaughter weight being 116 kg, 124 kg or 133 kg has been observed, and the CI from 75 kg LW onwards is 3.19, 3.24 or 3.48 (Latorre MA., et al., 2004). This effect is mainly due to the increase in the fat deposition rate, so the proportion of lean tissue/fat is lower from approximately 100 kg live weight onward.
Although it is obvious that the higher the slaughter weight the worse the CI, when deciding on the length of the fattening stage or on the slaughter weight we must bear in mind other factors that affect the financial results of the pig farms: for instance, the product that we want to market. On the other hand, it is important to remember that the optimal slaughter weight is not a constant value, but that it depends greatly on the price of the pig and the cost of the compound feed: the higher the price of the pig the higher the optimal slaughter weight, and the more expensive the compound feed the higher the reduction of the optimal slaughter weight (Dipietre, 2009).
According to our own calculations, for the same company, the maximum financial return went from 85 kg carcasses in year 2006 to 78 kg carcasses in year 2007. So, it is important to re-evaluate the slaughter weight goals, especially during those moments in which there are great changes in the market prices.
On the other hand, and although it is laborious, weighing some animals before sending them to the abattoir can mean great savings, so it is a good investment to have scales in the farm.
3. Health. When an animal suffers an infection there are a series of changes:
- the immune system becomes activated.
- the basal metabolism increases.
- the hormone secretion is altered: increase of the catabolic hormones (corticoids) and decrease of the anabolic ones (GH).
- the mobilization of the reserves is increased, so the carbohydrates, the protein and the fat reserves decrease.
The final result is a decrease in the protein synthesis in non-priority tissues, muscle proteins are degraded and the result is a growth loss and an increase in the CI (Bown, 2004). Controlling any disease that affects the CI of the pigs will always be a good investment.
A sanitary improvement that allows an improvement of 0.05 points in the CI means about 1€/pig.
4. Reproduction. The production improvement of the sows can mean a global compound feed saving because, approximately, the 17% of the compound feed consumption belongs to the gestation and the nursing stages.
Although we only consider the compound feed expense during the growing/fattening stage in order to reduce the CI, the fact of bearing in mind the compound feed consumption in previous stages can be of great help. In fact, there are some authors that prefer to use parameters that express better the feeding efficiency of the whole farm, the production pyramid or the company: the global CI or the sows-to-slaughter CI. We must bear in mind that a first parturition sow may have consumed some 750 kg of compound feed until it weans its first litter, and that a multiparous sow can consume some 450 kg of compound feed per cycle. The more piglets obtained by each sow the lower the impact of the compound feed on the total costs.
Any improvement in the reproduction stage that reduces the non-productive days or increases the longevity of the sows or the number of weaned piglets per sow will have a positive impact on this global CI.