The Issue

• Improvac eliminates boar taint but compared to entire males backfat can increase and the feed:gain ratio can be increased.
• It is important that diets have the correct level of amino acids to minimise these issues and maximise performance.
• But there is no published work on the lysine requirements of immunised males.

Our Aim

• To determine the response of immunised males and entire males to increasing levels of available lysine in their diet.

Our Methods

• Two sexes – entire males and immunised males (second vaccination received six weeks before slaughter).
• Five levels of available lysine from 0.32 to 0.75g available lysine per MJ DE.
• Diets fed for six weeks from 60 to 108kg kiveweight.

Our Findings

• Immunised males had a higher daily gain, lower feed:gain ratio, heavier carcass weight and higher P2 than entire males.
• Immunised males had a higher daily gain at lysine levels compared to entire males (Figure 1).

Figure 1. Change in daily gain of entire males and immunised males as the level of available lysine in the diet increases.

• Immunised males had a higher feed:gain ratio at higher levels of lysine than to entire males (Figure 2).

Figure 2. Change in feed:gain ratio of entire males and immunised males as the level of available lysine in the diet increases.

• P2 decreased as the level of lysine increased (data not shown).

What Does This Mean for Producers?

• Boar taint can be eliminated with the use of Improvac®
• Lysine requirement for immunised males to maximise growth performance and minimise carcass fatness over the liveweight and time period investigated is lower than for entire males.
• Talk to your nutritionist to determine the optimum lysine level for your genotype and environment.
• Further recommendations on the feeding regime for immunised males to come.

A copy of the final report is available by clicking here.