Evaluation of a method estimating real-time individual lysine requirements in two lines of growing–finishing pigs

Abstract

The implementation of precision feeding in growing-finishing facilities requires accurate estimates of the animals' nutrient requirements. The objectives of the current study was to validate a method for estimating the real-time individual standardized ileal digestible (SID) lysine (Lys) requirements of growing-finishing pigs and the ability of this method to estimate the Lys requirements of pigs with different feed intake and growth patterns. Seventy-five pigs from a terminal cross and 72 pigs from a maternal cross were used in two 28-day experimental phases beginning at 25.8 (±2.5) and 73.3 (±5.2) kg BW, respectively. Treatments were randomly assigned to pigs within each experimental phase according to a 2×4 factorial design in which the two genetic lines and four dietary SID Lys levels (70%, 85%, 100% and 115% of the requirements estimated by the factorial method developed for precision feeding) were the main factors. Individual pigs' Lys requirements were estimated daily using a factorial approach based on their feed intake, BW and weight gain patterns. From 25 to 50 kg BW, this method slightly underestimated the pigs' SID Lys requirements, given that maximum protein deposition and weight gain were achieved at 115% of SID Lys requirements. However, the best gain-to-feed ratio (G : F) was obtained at a level of 85% or more of the estimated Lys requirement. From 70 to 100 kg, the method adequately estimated the pigs' individual requirements, given that maximum performance was achieved at 100% of Lys requirements. Terminal line pigs ate more (P=0.04) during the first experimental phase and tended to eat more (P=0.10) during the second phase than the maternal line pigs but both genetic lines had similar ADG and protein deposition rates during the two phases. The factorial method used in this study to estimate individual daily SID Lys requirements was able to accommodate the small genetic differences in feed intake, and it was concluded that this method can be used in precision feeding systems without adjustments. However, the method's ability to accommodate large genetic differences in feed intake and protein deposition patterns needs to be studied further.

Effect of a lysine depletion–repletion protocol on the compensatory growth of growing-finishing pigs1

“…With respect to Lys utilization efficiency, the pigs that were the most efficient in retaining Lys for muscle deposition were those that had been restricted to 70% of their estimated Lys requirements, whatever the animals' BW. These results were also observed in a previous study using similar animals and feeds (Cloutier et al, 2015) as well as in other studies (Heger et al, 2008;Zhang et al, 2012). The pigs that had been restricted during the first feeding phase tended to maintain this greater efficiency during the second phase, but the effect was not significant.…”

“…In the pigs in the present study that received, from 25 to 50 kg, 70% of their SID Lys requirements, Lys utilization efficiency exceeded 100%, a result that seems metabolically improbable but is in keeping with the results of a previous study using similar animals and feeds (Cloutier et al, 2015). After repeated analyses of this nutrient, the possibility that feed Lys was underestimated was discarded in favor of the hypothesis that retained Lys was overestimated.…”

“…It is possible that dietary Lys restriction was lower than expected in the finishing stage, which would explain these results. However, a study that was similar to the present one and used the same animals and feeds demonstrated that the method used to determine the animals' requirements was sound overall (Cloutier et al, 2015).…”

“…The Institutional Animal Protection Committee at Agriculture and Agri-Food Canada's Dairy and Swine Research and Development Centre, in Sherbrooke, QC, Canada, reviewed and approved the protocol for the experiment. The experimental diets, estimates of Lys requirements, measurement methods, and analytical procedures are similar to those described by Cloutier et al (2015).…”

Precision feeding can significantly reduce lysine intake and nitrogen excretion without compromising the performance of growing pigs

“…The amount of protein contained in the BW gain of each pig was estimated by regression analysis relating within each feeding period the observed performance variables and the protein content in live weight gain (Rivest J and Pomar C, unpublished data). This method of estimating nutrient requirements has been described previously (Hauschild et al, 2012;Pomar et al, 2014b) and validated in two previous studies (Zhang et al, 2012;Cloutier et al, 2014).…”