Nutrition for gilt rearing

When rearing gilts, it is essential they are fed correctly. Read our information on nutrient recommendations to help maximise the lifetime productivity of your gilts.

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Nutrition

The primary objectives of gilt rearing, whether the pigs are home-reared or bought in, is to ensure that gilts are fed correctly to ensure optimal lifetime productivity.

Nutrition is important in the development of gilts and can help to improve post-farrowing condition in the first parity, improve litter size and reduce the number of empty days.

Reproductive failure is one of the most common reasons given for premature culling, so giving gilts the best possible start will help to reduce this and the associated losses in revenue. Correct nutrition can also help to reduce foot and leg problems which can cause significant problems in the breeding herd, which also reduces culling.

Rearing

When rearing gilts and finisher pigs, it is important to remember they have different nutritional requirements; therefore, ideally, they should be housed separately and fed to the required condition.

When rearing gilts, the aim is to prepare the animal for a long productive life. The nutritional strategy is largely determined by target weight, age and in some cases P2 targets suggested in the genetic companies’ guidelines. Feeds are lower in amino acids and energy than finishing feeds and higher in minerals to ensure sound skeletal development.

With genetic improvement, it is increasingly difficult to achieve targets when pigs are ad lib fed – weight for age is often too high. Some degree of feed restriction may be needed although it is not always practical.

Nutrient recommendations for gilts

Table 1 gives typical feed specifications for gilt rearing.

These feed specifications should be used as a guide. They are based on what nutritionists consider appropriate. Consult your nutritionist for further recommendations.

Table 1. Nutrient specifications for gilt rearing

Nutrients

Gilt rearer, 30-60 kg

Gilt rearer, 60-100 kg

Gilt rearer, 100 kg+

Net energy (MJ/kg)

9.7-9.9

9.5-9.7

9.3-9.5

Crude protein (%)

13.0–14.0

13.0-14.0

13.0-14.0

Crude fibre (%)

4.5–6.0

4.5-6.0

4.5-6.0

Standardised ileal digestible amino acids

Lysine (%)

0.93-0.96

0.77-0.80

0.62-0.65

Methionine (ratio)1

0.30-0.33

0.30-0.33

0.30-0.33

Methionine + cysteine (ratio)

0.58-0.62

0.58-0.62

0.58-0.62

Threonine (ratio)

0.65-0.66

0.67-0.68

0.68-0.69

Tryptophan (ratio)

0.18-0.19

0.18-0.19

0.17-0.18

Valine (ratio)

0.67-0.69

0.67-0.69

0.67-0.69

Isoleucine (ratio)

0.54-0.56

0.54-0.56

0.54-0.56

Histidine (ratio)

0.34-0.36

0.34-0.36

0.34-0.36

Minerals

Calcium (%)

0.75-0.80

0.70-0.75

0.67-0.70

Digestible phosphorus (%)2

0.31-0.33

0.27-0.29

0.25-0.27

Sodium (%)

0.19-0.21

0.19-0.21

0.19-0.21

Copper (mg/kg)3

0.25

0.25

0.25

Vitamins

Vitamin E (IU/kg)

50

50

50

1Amino acids are presented as ratios to standard ileal digestible lysine 

2Digestible phosphorus level is based on diet formulation without the use of phytase. If phytase is being used, phosphorus levels must be readjusted. The addition of phytase to the diet is recommended for improved digestibility

3The maximum permitted level of copper in feed for all pigs over 8 weeks post-weaning is 25 mg/kg

Additional additives to consider

In addition to the above nutrient recommendations, the following additives may be considered for gilt rearing:

  • Phytase

Adding phytase to gilt rearer diets has been shown to increase the nutritional value of feed by increasing the release of phosphorus

Quantity of feed

Feed intake during rearing will depend largely on gilt weight for age.

Gilts may often be fed ad lib until a certain weight, after which they are fed restrictively to ensure the correct body condition. Broadly speaking, a feed allowance of 2.6 kg/day is sufficient, with further monitoring and adjustment to establish and maintain an average body condition score of 3.0 at entry to the farrowing house.

Feeding requirements by production system

During rearing, gilts will be less sensitive to temperature changes than gestating or lactating sows; however, seasonal changes in feed intake can be expected – particularly for gilts reared outdoors.

During the summer months, a drop in feed intake may be observed and, if body condition is affected, a more nutrient dense feed can be considered. Conversely, during the winter, gilts may have an increased requirement for energy. Increasing feed allowance can be beneficial if a drop in body condition is seen.

Feed form

Feed is available in several different forms, including pellets, meal, nuts and rolls. There are benefits of each and, ultimately, the type of production system and feeding equipment available may dictate choice.

In outdoor systems, rolls and nuts may be used. These are beneficial because the gilt will forage from the ground and, while on straw in the rearing period, will help to increase intake and reduce wastage.

Pellets have been widely reported to increase feeding efficiency and feed intake. This may be explained by the finer grist size giving improved availability of nutrients and quicker digestion leading to increased intake. The compact nature allows more feed to be consumed in the same length of time, resulting in improved growth performance.

In the UK, meal is generally a coarse grist product, which increases flowability and reduces blockages and dust. However, studies have shown that, generally, meals have a higher feed conversion ratio than pellets.

Frequently asked questions

Homebred gilts should ideally be separated and fed differently from approximately 12 weeks of age (around 40 kg), although practically it is often easier to do this from 65 kg and not a major compromise. Some producers separate earlier but continue feeding the same rations as the growing herd.

From 100 kg, a gilt finisher feed should be fed. Historically a dry sow diet was then often fed but with genetic improvements in our animals this is not ideal.

Different breeding companies have different recommendations for the correct age or weight at which to breed, so it is worth consulting with them before making a decision.

Recommendations vary from approximately 135-150 kg at first mating, a lifetime growth rate of 600-750 g/d, P2 to 14-16 mm and second or third oestrus.

The extent to which these standards truly reflects differences in the genotype is unclear. However, feeding the gilt in lactation is absolutely crucial; nuances around gilt rearing pale into significance by comparison.

Flush feeding is the practice of increasing the feed intake between the first and second heat, with the aim to increase the ovulation rate and subsequently the number of piglets born per litter.

This can be beneficial to gilts that have been fed restrictively; however, for those that have been fed ad libitum throughout the rearing period, there is unlikely to be a benefit.

primary. diets.

This work was written in conjunction with ABN, Primary Diets and Premier Nutrition.

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