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Feeding weaned sows

Ioannis Mavromichalis
One of the least discussed topics in pig nutrition is how to feed the sow after piglets are weaned and until she shows the first signs of estrous. There are many programs, ideas, and methods! They range from starvation in the first couple days to feeding ad libitum to achieve the so-called 'flushing effect'. Based on my experience, no two farms use the same method, and there is at least more than a few programs that are used successfully.

The area that requires some further discussion here concerns the influence of the amount of feed from weaning to mating on subsequent litter size - and this is to be differentiated for gilts and sows. The following may explain why similar practices lead to different, and quite often disappointing, results in several farms.
Gilts that have been raised on an ad libitum or near ad libitum feed intake program, including those that were raised on a limit-feeding but generous program, end up quite heavy for their age at mating time. Such gilts almost invariably will fail to benefit from increasing their feed intake in the last couple weeks before mating. On the other hand, great results in terms of ovulation and  subsequent litter size are to be expected on increasing feed intake (up to twice the normal daily allowance) in gilts that reach mating time on the lean side of body condition.
For sows that have just completed a lactation period, flushing works best when body condition has been allowed to greatly deteriorate during lactation. Here, again up to doubling of normal (maintenance levels) feed intake can speed up ovulation and increase subsequent litter size.
However, this is a 'cheap' method to influence productivity as it will only continue the rapid decline of sow condition and reduce overall lifetime productivity. It is best to address the issues of low feed intake during lactation (in most cases a result of overfeeding during gestation) and keep sows on maintenance levels during weaning-to-mating period.
I would be very interested to read your thoughts on this neglected topic!


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    Dr Nikolaos Kotrotsios

    At one time or another, there has been reason to suppose that, after weaning, both a generous ratio and a restricted ration might enhance the number of ova released and the number of embryos safely implanted into the uterine wall. It would now appear that extremely heavy feeding before conception and in the first 3 weeks of the pregnancy may be counter productive but very high feeding levels after weaning are in any event rather difficult to achieve it.
    The question is coming more interesting while it's based on the differences in management factors between farms. According to my opinion it's very important to take in consideration the natural body condition of the sow after piglets are weaned. So I will consult to treat each case individually getting the best results. In fact modern genetic material of the sows, gives a higher littersize with an rapid increasing of the weight of piglets. Most of the cases the sow is unable to have a good reaction in that and at the end of lactation period, body condition is lower than the normal, thin to emaciated score. The appetite of the lactating sow is lowest immediately after farrowing, increasing gradually up to the third week of lactation. Sows do not compensate for low feeding levels the first week post farrowing by eating more later in lactation and therefore will lose more body weight and wean lighter pigs as a result. Farms that use a gradual increase in feeding program during early lactation have lower litter weaning weights and longer wean to estrus intervals compared to farms using a rapid increase in early lactation feed intake. This emphasizes the importance of maximizing feed intake as soon as possible following farrowing and throughout lactation in order to limit sow body weight loss, maximize piglet growth rate and optimize subsequent reproductive performance. Consequently lactation weight losses may have involved loss of both fatty and proteinaceous body tissues. This being the case, logic would suggest a high quality, high nutrient dense (protein and energy) diet as appropriate for the weaning to conception interval in order to replenish lost tissue and return the body to rebreeding condition. Finally, we should take into consideration that the duration weaning to mating period is not only affected by the balanced feeding ratio and feed intake but also by many environmental, genetic, metabolic and physiological factors.

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    The effects of flushing for sows with a poor condition are well known to me.
    But what I don't know is the effect of flushing methods on "normal" sows. Since last year we use a mixture with high levels of sugar and starch. They should keep the insulin-level high an help to promote oestrus. What do you think about this concept?

    Another strategy is to continue to feed the sow the lactation diet until she is mated. Are there any studies about the success of this concept?

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