The Effects of Feeding Narasin (Skycis) on Late Finishing Pig Performance

The purpose of this study was to determine the effects of narasin (Skycis, Elanco Animal Health, Greenfield, IN) on growth and performance of pigs during late finishing. In study 1, 240 barrows (Smithfield Premium Genetics, Rose Hill, NC) were weighed (initial BW 82.3 kg) and randomly allocated to 1 of 2 treatments: Control (CON) or narasin 15 ppm for 35 d. All pigs were then fed CON for 7 d prior to harvest. Each treatment had 15 pens containing 8 pigs per pen (0.87 m² per pig). In study 2, 416 barrows and gilts (PIC Landrace × Large White composite females mated to Smithfield Premium Genetics) were weighed (initial BW 84.5 kg) and randomly allocated to 1 of 2 treatments: Control (CON) or narasin 15 ppm for 35 d. Each treatment had 26 pens containing 8 pigs per pen (0.78 m² per pig). Pigs were weighed on d 0, 35 and at harvest to determine start weight, harvest weight and ADG. Feed issuance and weigh backs were recorded in order to determine ADFI and G:F. Pigs were individually tattooed and transported to a commercial packer for harvest and collection of HCW. Data were analyzed in SAS using PROC GLM. Fixed effects included treatment, room and sex. Pen was the experimental unit. In study 1, pigs fed narasin had greater (P < 0.05) ADG (1.185 vs. 1.140 kg) and ADFI (3.33 vs. 3.24 kg) than pigs fed the CON diet. In study 2, gilts fed narasin tended (P = 0.08) to have greater ADG (1.13 vs. 1.08 kg) and had superior (P < 0.05) G:F (0.362 vs. 0.347) when compared to CON fed gilts. Across both studies 1 and 2, pigs fed narasin had greater (P < 0.05) ADG (1.138 vs. 1.100 kg) and G:F (0.363 vs. 0.355) than CON. Market weight CV tended (P = 0.09) to be lower for narasin when compared to CON (8.4 vs. 9.1%). Results showed that supplementing diets with narasin for 35 d prior to harvest significantly improved growth performance and feed efficiency of finishing pigs.