Effect of parity and stage of gestation on growth and feed efficiency of gestating sows.

The effects of parity and stage of gestation on female growth criteria, and reproductive performance were evaluated on a commercial sow farm. A total of 712 females (Camborough, PIC, Hendersonville, TN) were group-housed and individually fed with electronic sow feeders. Gilts (parity 1) and sows were offered 2.0 and 2.26 kg of feed per day (4.7 and 5.3 Mcal NE per day), respectively. Females were moved from the breeding stall to pens on day 5 of gestation. A scale was located in the alleyway after sows left individual feeding stations. Feed intake and BW were recorded daily throughout gestation generating values for ADFI, ADG, and G:F for each sow. Data were divided into 3 parity groups: 1, 2, and 3+ and gestation was divided into 3 periods: day 5 to 39, 40 to 74, and 75 to 109. From day 5 to 39, ADFI was decreased (P < 0.05) for parity 3+ sows compared to the other periods of gestation. Parity 2 sows, although provided the same feed allowance, had greater (P < 0.05) ADFI during the first period of gestation than parity 3+ sows. Parity 1 and 2 sow ADG increased (P < 0.05) from day 39 to 74 of gestation, then decreased (P < 0.05) from day 74 to 109 of gestation. Parity 3+ sow ADG increased (P < 0.05) in each subsequent period of gestation. Parity 1 sows had the greatest (P < 0.05) ADG in comparison to parity 2 and 3+ sows in each period of gestation. Regardless of parity group, G:F was poorest (P < 0.05) from day 5 to 39 of gestation compared with sequential periods of gestation. Parity 1 sow G:F was greater (P < 0.05) than parity 2 and 3+ sows for all periods of gestation. Backfat gain indicated that parity 1 sows maintained backfat (approximately 18 mm) while parity 2 and 3+ sows gained (P < 0.05) approximately 1 mm backfat throughout gestation. Total born was greatest (P < 0.05) for parity 3+ sows with parity 1 sows marginally greater (P < 0.10) than parity 2 sows. Although there was statistical evidence (P < 0.001) for a positive correlation between BW gain and total born in parities 1 (r = 0.23; P = < 0.001), 2 (r = 0.15; P = 0.035), and 3+ (r = 0.29; P < 0.001), these correlations are very weak. Overall, this study indicates that parity 1 sows have the greatest G:F in gestation and that there is a lack of evidence for strong correlations between feed intake, growth, and reproductive performance.