Increasing Dietary Lysine Impacts Differently Growth Performance of Growing Pigs Sorted by Body Weight.

ABSTRACT

An experiment was conducted analyzing whether growing pigs classified in different initial body weight categories (BWCAT) have a different response to increasing standardized ileal digestible lysine to net energy ratio (SID LysNE), to assess whether light pigs might benefit from being differentially fed. A total of 1170 pigs in pens of 13 were individually weighed, classified in 3 BWCAT (Lp 32.1 ± 2.8 kg, Mp 27.5 ± 2.3 kg, and Sp 23.4 ± 2.9 kg), and afterwards pens were randomly allocated to 5 dietary SID LysNE treatments (3.25 to 4.88 g/Mcal) fed over 47 days. Results reported a greater linear improvement of growth and feed efficiency of Sp compared to Lp when increasing SID LysNE. Modelling the response to SID LysNE using quadratic polynomial models showed that the levels to reach 98% of maximum growth from day 0-47 were 3.67, 3.88, 4.06 g SID Lys/Mcal NE for Lp, Mp, and Sp, respectively. However, due to the overlapping SID LysNE confidence intervals at maximum performance, it was not possible to determine if requirements were different between BWCAT. Summarizing, the results suggested that feeding small pigs greater SID LysNE than large pigs can improve their performance and increase the efficiency of the overall production system.