Gilt feeding – Ad libitum feeding

Optimum feeding of gilts by ad libitum feeding

Gilts represent the future production of the sow herd, and DanBred gilts come with an extraordinary genetic potential for reproductive performance.

Careful attention to the feeding of the DanBred gilt will be rewarded in the farrowing unit- setting a prime starting point on the road to release the genetic capability for optimum lifetime performance.

The recommended feed curve will ensure a balance of the feed amount in relation to the age and weight of the gilts as shown in figure 1 (on the left).

The huge potential for growth in the DanBred animals means that there must be a focus to limit the growth rate in the DanBred gilts, which is why the feed energy level is a very important factor when working with DanBred gilts.

The optimum lifetime production for DanBred gilts is reached when the gilt is mated for the first time in the second heat, at the age of 230-250 days weighing between 140-160 kg with a back-fat thickness of 14-15mm at the P2 measuring point (2).

Moderation of gilt growth

The feeding strategy for DanBred gilts is set to meet nutrient requirements as well as maximisation of long-term productivity.

A daily gain of 750-800 g/day from 30 kg to 140 kg will lead to the best possible basis for long-term reproduction productivity in DanBred gilts [2].

Feeding of DanBred gilts should ensure a steady continuous but controlled weight gain throughout the period of growth. Expected weight development from following the DanBred recommendations is shown in figure 2.

The target is to initiate puberty and the onset of the oestrus cycle, support the pre-pubertal mammary development and maximise the productivity of litter size and longevity.

Studies indicate that the age of the gilt, as well as the correct introduction of boar contact, are the main factors when it comes to the onset of puberty [2][3].

The amount of body fat in the gilts might help the onset of puberty in gilts [1].

The managed growth rate for replacement gilts has shown to positively correlate with sow longevity because the moderated growth rate has a positive effect on bone growth giving the gilts stronger legs and thereby increasing longevity in breeding animals [5].

In a 2004 trial, Vestergaard et. al. found that 50 to 60 % of sows were culled due to leg problems and this can be related to unmanaged growth rates during gilt development.  Managing growth and increasing fat deposit through feeding will give lighter but slightly fatter gilts at the age of first mating.

Gilt body fat content can play a role in the onset of puberty, therefore, it is important to ensure a back fat target of 15 mm  (or at least 14 mm) at first mating.

Mammary development in the replacement gilts is not affected by the more linear growth curve, as the vast part of the udder, growth happens in the last third of gestation [2].

Size of first litter might be marginally decreased at steady growth rate, but flushing the gilts before mating has proven to be a very efficient way of increasing the ovulation rate at mating in the second oestrus and thereby enlarge the litter size [1].

Easy gilt feeding to reach optimum DanBred reproductivity targets

To exploit the full potential of DanBred gilts the following targets should be met at first mating:

• Age: 230-250 days (32-35 weeks)
• Weight: 140-160 kg
• 14-15 mm back fat at the P2 measuring point.
• First mating on the 2^ndheat

Start boar exposure daily at the age of 200 days (28 weeks).

To efficiently control daily gain, the DanBred gilts must be fed diets containing less crude protein and lysine than finisher pigs. Restricted phase feeding with three different diets from 30 to 140 kg is recommended as shown in figure 1.

If ad libitum feeding is the only possibility, the daily gain should be controlled as ad libitum increase the risk of daily gain exceeding the recommendation.

From 30-110 kg keep the energy density between 9.2-9.5 MJ NE/12.0-12.5 MJ ME/0.97-1.00 EW per kg feed and feed increased amounts of fibre. Additionally, follow the lysine and protein recommendations shown below.

At a weight of 110 kg, the diet should be changed to promote the deposit of back fat. Energy density should be kept but Standardized Ileal Digestible (SID) lysine should be reduced and the gilts should be fed based on body condition to ensure a growth rate within the desired level.

The table below shows the recommended content of selected nutrients per kg feed when using ad libitum feeding for gilts from 30-110 kg and for gilts above 110 kg, respectively.

*NE = Net energy,; ME = Metabolic Energy; EW= Net Energy in Dutch evaluation system

References

[1] Beltranena, E., Aherne, F. X., Foxcroft, G. R. og Kirkwood, R. N. (1991): Effects of pre- and postpubertal feeding on production traits at first and second estrus in gilts. Journal of Animal Science. 69: 886-893.

[2] Bruun, T.S., Sørensen, G.; Tybirk, P. (2014): Baggrund for næringsstofnormer til polte fra 30 til 140 kg. Notat nr. 1418, Videncenter for Svineproduktion

[3] Foxcroft, G., Beltranena, E., Patterson, J., Williams, N., 2005. The biological basis for implementing effective replacement gilt management. In: Proceedings of 2005 Allen D. Leman Pre-Conference Reproduction Workshop, Saint Paul, Minnesota, 17–20 September, pp. 5–25.

[4] Sørensen, G. (2006): Fodring af polte i opvækstperioden. Meddelelse nr. 741. Videncenter for Svineproduktion, Den rullende afprøvning.

[5 ]Sørensen, G. (2011): Betydning af poltes væksthastighed for livslængde og produktivitet. Meddelelse nr. 916, Videncenter for Svineproduktion.

[6] Vestergaard, K. (2004): Afgangsårsager hos søer – samt obduktionsfund hos aflivede og selvdøde søer. Meddelelse nr. 656, Landsudvalget for Svin.