219 Effect of stocking density on F1 gilt grow-finish performance

Abstract

Abstract As replacement rates in the swine industry have increased, gilt development units have increased the number of females developed in the same allotted space. The impact of decreasing space is not well understood on the developing gilt. Therefore, the objective of this study was to evaluate differences in grow-finish performance for developing gilts housed at different stocking densities. At 10 wk of age 824 F1 females (DNA L241, DNA Genetics, Columbus, NE) were randomly allotted to 12 pens per treatment of either 0.71 m2 (n = 360), 0.93 m2 (n = 264), or 1.25 m2 (n = 204). Body weights (BW) were individually collected at 10, 24, and 31 wk of age. Backfat and loin depth were measured using an Exxago Ultrasound between the 10th and 11th rib at 24 and 31 wk of age. Feed consumption was measured at the pen level using a Feed Logic system. Mortality date, reason, and BW were recorded throughout the grow-finish phase. At 10-wk of age, there was no significant difference in BW between the treatments. Differences in BW were observed between treatment 0.71 m2 at 119.3 kg compared with 0.93 m2 and 1.25 m2 at 123.4 kg and 125.6 kg, respectively (P < 0.01). All stocking densities were significantly different (P < 0.01) at 31 wk of age with 0.71 m2 at 142.4 kg, 0.93 m2 at 152.4 kg and 1.25 m2 at 156.5 kg. Backfat and loin depth were significantly different at 24 wk for 0.71 m2 compared with 0.93 m2 and 1.25 m2 (P < 0.05). At 31 wk of age, all treatments were significantly different for backfat with 0.71 m2 at 16.1 mm, 0.93 m2 at 18.0 mm and 1.25 m2 at 19.1 mm (P < 0.05). Feed conversion was not different across treatments from 71 d of age until 84 d of age and from 84 until 111 d of age. However, feed conversion was significantly different from 111 d until 167 d of age for 0.71 m2 at 3.83 compared with 1.25 m2 at 3.40 (P < 0.10). Mortality was not different between treatments (P < 0.05). Gilts that were assigned to the least square foot treatment grew slower and had decreased backfat and loin depth. This could potentially impact the timing of the estrus detection and matings in the replacement gilt population. Overall, producers looking to improve the BW of females entering the breeding herd should evaluate increasing the space allotted per female in their gilt developer.