Lysine requirements of modern genotype finisher pigs

Moore et al. (2013) determined the performance responses to dietary lysine concentrations of the modern genotype pig from 50 to 100 kg liveweight (LW) and found that the lysine requirement to optimise growth performance in this weight range was higher by approximately 10% than that being used by the Australian industry. The aim of the current study was to confirm the optimal standardised ileal digestible lysine (SID Lys)/MJ digestible energy (DE) ratio for a modern genotype of entire male and female pigs from 60 to 100 kg LW obtained in a research facility.

A total of 392 pigs (Large White × Landrace × Duroc) was used in a 2 × 7 factorial arrangement of treatments. The treatments were: sex (entire males vs females); and SID lysine concentrations (0.40, 0.46, 0.52, 0.58, 0.64, 0.70 and 0.76 g SID Lys/MJ DE). The diets contained 14.0 MJ DE/kg and were fed for 6 weeks from 63.6 ± 0.44 to 103 ± 0.55 (mean ± SE) kg LW. Pigs were housed in groups of seven and there were four replicates/treatment. The data were analysed using the linear plateau and quadratic models fitted to the treatment means (Nutrient Response Models Version 1.1, Vedenov and Pesti 2008; O’Connell et al. 2006). The results from the linear plateau and quadratic models were then averaged to determine the requirement (Williams et al. 1984).

For female pigs, the SID Lys concentrations to maximise daily gain and minimise FCR were 0.58 and 0.58 g/MJ, respectively (Fig. 1). For entire male pigs the SID Lys concentrations to maximise daily gain and minimise FCR were 0.64 and 0.63 g/MJ DE, respectively (data not shown). These SID lysine concentrations confirm optimal SID Lys/MJ DE ratio for a modern genotype of entire male and female pigs from 60 to 100 kg LW as they are similar to the results from Moore et al. (2013) in a research environment. These values for female pigs are similar to the SID Lys requirement estimated in Australian commercial facilities (Moore et al. 2015).

Fig. 1.  Effect of dietary SID Lys content on (a) daily gain and (b) FCR for female pigs from 63 to 98 kg LW (n = 4, mean ± SE). Data has been fitted with linear plateau (- - -) and quadratic (…) models.