28 December 2001

Breeding gilts need own feed strategy

By Hannah Velten

BREEDING gilts must be fed correctly so they build up fat reserves and strong bones to ensure longevity.

Pauline Lee, pig research manager at ADAS Terrington, says breeding gilts should be treated differently to slaughter pigs from about 70kg.

"Although gilts are bought in at 35kg on many units, disease concerns mean there is a move towards rearing F1 home-bred replacement gilts. Without the correct feeding early in life gilts may have to be culled for poor performance."

Ideally, home-reared gilts should be housed separately from slaughter pigs at 70kg and put onto a special feeding strategy (see table 1).

Phase two of the feeding strategy uses a specialised gilt diet, says Dr Lee. "This feed is designed to supply energy, allowing gilts to grow slowly and build fat reserves.

"But it must also provide adequate levels of lysine to continue lean growth, which is important for reproductive system development."

The diet also contains higher intakes of calcium and phosphorus than required for slaughter pigs to promote strong bones. "Leg weakness comes fairly high on the list of reasons to cull," she adds.

Phase three provides gilts with the high nutrient intake they need for a flushing effect before mating. "Increased intake prompts ovaries to produce more eggs, which helps achieve better conception rates."

From mating to late pregnancy, gilts must be allowed to steadily put on weight as they are still maturing.

During late pregnancy gilts will eat less as foeti grow, so require the higher protein and energy levels found in a lactating sow ration, adds Dr Lee. Through lactation, appetites will increase to cope with milk production demands.

Dr Lee admits that on some units there may not be storage space for specialised gilts diets, but producers can use sow diets to develop a compromise feeding strategy.

Target nutrient intakes (see table 2) should be compared with compromise diet ingredients and a feeding plan devised.

"When compromise diets need to be fed in high quantities to reach nutrient targets, increasing the number of feeds may encourage gilts to eat more," she advises. &#42

Fine-tuning gilt diets from 70kg liveweight is essential to maximise future performance, says ADAS pig researcher Pauline Lee..


Phase 1 35-70kg: Medium density finisher diet fed ad-lib.

Phase 2 70kg to 21 days pre-mating: Specialised gilt rearing diet fed at 2.5-3kg/day.

Phase 3 21 days pre-mating to mating: Specialised gilt rearing diet fed ad-lib.

Phase 4 Mating to late pregnancy: Specialised gilt rearing diet fed at 2-2.5kg/day.

Phase 5 Late pregnancy to weaning: Lactating sow diet fed to appetite.

Phase 6 Weaning to mating: Specialised gilt rearing diet fed ad-lib.


DE CP Lysine

intake intake intake

(MJ/day) (g/day) (g/day)

Phase 1 35 375 32

Phase 2 44 450 26

Phase 3 55 560 32

Phase 4 30 300 18

Phase 5 48 490 28

Phase 6 60 800 45