ASK THE SOW WHAT SHE NEEDS !!!
With the increase of sophistication in Swine production, it is more and more relevant to adjust the animal diets to each situation. For the past years, we have been managing nutrition based on average requirement per stage. All sows were having similar feed with slight adjustment on quantity sometimes. To be more effective, it is clear now that we need to calculate more precisely the requirement of each animal according to their situation.
If the sow is in first cycle at 150kg body weight and produce 10 piglets, she may not need the same diet as another sow in her fifth cycle at 250kg with 15 piglets. We need to formulate according to each sow context to save costs on younger sow and ensure optimal production on heavier sows
To do so, we need a way to relate the calculation of diet requirement to the situation of the animal. A model of calculation has been developed by INRA (France) based on thousands of field data. J.Y.Dourmad & al. developed equations to correlate energy requirement to animal weight, growth, litter size, external temperature. Similar model exists as well for Lysin requirement.
During gestation, requirements are based on maintenance (including activity and thermoregulation) and foetal/uterus and maternal growth.
During lactation, nutrient and energy requirements are based on the requirements for maintenance, milk production and maternal growth
In this article, we will limit ourselves only to the gestation stage. If you want more information on the lactation stage, do not hesitate to come back to me. Other models of calculation have been developed by other research institutes but conclusions are quite similar.
Energy needs for maintenance during gestation: For the gestating sow, regardless of the reproductive cycle, the daily maintenance need is 100 kcal ME / kg of Metabolic body weight (or 77 Kcal of NE) at the Thermo-Neutral Zone (18-22°C). As you notice, we do not use the standard animal weight but the metabolic weight. Energy expenditure and basal metabolic rate depend on the amount of metabolically active tissue in the body, rather than total body weight. To assess the metabolic body weight, we are using the standard body weight at power 0.75 – (Power (BW, 0,75)). The table below illustrates this correlation between body weight, metabolic body weight and daily energy requirement for maintenance in ME and in NE.
These recommendations have been built for sows in gestating cages. If the sows are in free station, we need to increase maintenance needs by 15%. We notice in this table that the energy requirement for sows in 7thparity are 60% higher than the needs for sows at their first parity. If we want the sows to keep being productive, we need to increase the supply of energy to cover their maintenance requirement. Energy needs for the sow body growth during gestation: During the gestation, the diet allows the proteins and lipids accretion in the maternal tissues in order to compensate the losses and to prepare the sow for the next lactation. Furthermore, the mature bodyweight being reached only towards the fourth cycle, it is necessary to cover the nutritionals needs to insure a sufficient growth (around + 20 kg BW/reproductive cycle). We therefore need to assess the body weight lost during the previous lactation and add on the top between 40 to 20kg of growth during the first 4 cycles (see above table of sow body weight according to parity) The need of energy can be estimated by: 37 Kcal ME / day / (or 29 Kcal NE) / additional kg of weight, and for each mm of fat deposition: 126 Kcal ME / day (or 96 Kcal NE). Energy needs for uterine contents during gestation: The energy required for uterine contents is calculated according to the weight of the litter at birth. The daily need of energy can be estimated at 15 Kcal ME (or 11 Kcal NE) / kg litter weight. To summarize the different categories, I included the values recommended by INRA into the table below
If we take the example of a sow of 250kg who will gain 15kg of weight and 5mm of fat during the gestation and who will give birth to 12 piglets of 1.3kg each, we can calculate the daily energy needs as follows
This example underlines the importance of energy requirement for maintenance that represents 82% of the total requirement for a sow at 5thparity and can even be higher for heavier sows. The calculation above is an average requirement during the 114 days of gestation but the requirement is different depending the period of gestation. During the first third of gestation (first 5 weeks), the sow needs to recover from the loss in lactation and rebuild reserves. This period will represent 37% of the total gestation requirement. The second third represent only 30% of total requirement. This is the period with the lower requirement. The last third of the gestation period is critical for the development of the uterus and the foetus. That period will count for 33%.