199 Phytosorb improves feed efficiency in pigs of two different commercial Duroc sire lines in late finishing compared with tri-basic copper chloride

Abstract The objective of this experiment was to determine whether Phytosorb could replace tribasic copper chloride in grow-finish rations with equal or better performance, and evaluate this in two Duroc sire lines. A total of 1,080 growing pigs [initial body weight (BW) = 35.3 ± 1.05 kg) from DNA female with 2 different sire lines (A and B) were randomly assigned to 2 dietary treatments in a randomized complete block design. There were 27 pigs in each pen and 10 replicate pens per treatment. The 2 dietary treatments were 1) standard diet with an additional 150 ppm of Cu supplementation (CON); 2) standard diet without copper supplementation + 0.45 kg of Phytosorb (PHY) a source of natural flavors and soy lecithin. Body weight and feed disappearance were recorded by pen on d 0, 21, 35, 49, 64, and 77, and were used to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). After d 77, an equal number of pigs from each pen were weighed and marketed over 5 individual cuts. Data were used to calculate all parameters and were analyzed using the GLM procedure in Minitab with Fisher’s t-test determining differences between treatments. The initial model included treatment, genetics (sire lines), and the interaction between treatment and genetics, however, the interaction was excluded in the final model due to being non-significant on the response criteria. Results indicated that ADG was greater (P < 0.05) and ADFI tended (P < 0.10) to be greater in pigs fed CON compared with pigs fed PHY from d 0 to 64 Table 1). G:F was greater (+5.9%, P < 0.05) from d 64 to 77, and G:F tended (+3.8%, P < 0.10) to be greater from d 64 to market weight (MKT; approximately 104 to - 134 kg BW) in pigs fed PHY compared with pigs fed CON. For the overall finishing phase (approx. 35.5 to 134 kg BW), ADG tended to be greater (P < 0.10) in pigs fed CON compared with pigs fed PHY but no differences in ADFI and G:F were observed. For genetics, there were G:F differences (P < 0.05, respectively) between sire line A and B from d 0 to 64, d 64 to MKT, and d 77 to MKT and overall finishing phase. Phytosorb was not able to replace copper in early finishing; the response during this phase was what we would expect copper to do. In late finishing, however, these results demonstrate that Phytosorb may give equal ADG, with an improved G:F ratio leading to an improved cost per kg of gain as compared with feeding tribasic copper chloride. This feeding strategy would support environmental sustainability by reducing the usage of copper in finishing diets.