Relationship of gestation protein and feed intake level over a five-parity period using a high-producing sow genotype.

High-producing Landrace-Large White crossbred gilts (n = 50) involving 198 farrowings were used to evaluate dietary gestation protein (13 vs 16% CP) and gestation feed intakes (Control vs High), and their interaction, over a five-parity period on sow reproductive performance. Gestation feed intake for Control was 1.81 kg/d during parity 1, increasing by .09 kg for each successive parity. The daily feed intake for High was greater by .13 kg or approximately 450 kcal ME at each respective parity. The experiment was a 2 x 2 in a randomized complete block design conducted in two replicates with parity nested within sow groups. Sow weights and backfat thickness were determined at various intervals. A lactation diet containing .90% lysine in parity 1 and .80% lysine during parities 2 to 5 was fed to all sows from farrowing to weaning (21 d). Sow and pig weights, feed intakes, and colostrum and 21-d milk samples were collected during each lactation. The High feed intake and the 13% protein diet resulted in greater (P < .01) backfat thicknesses, and the effects were additive. Backfat thickness declined quadratically (P < .01) by parity and from late gestation to the rebreeding period of the following parity. The High feed intake resulted in a larger litter size (P < .01), whereas dietary gestation protein concentration had no effect on parturition performance. Sows in each parity consumed more (P < .01) feed from 0 to 7 d postpartum and for the overall 21-d lactation period (P < .01) for parity 1 when the 16% gestation protein had been fed. Gestation feed intake regimens did not affect lactation feed intake. Neither gestation variable affected colostrum or 21-d milk fat, but concentrations declined (P < .01) in all groups after parity 2. Parity 1 litters were heavier at 14 and 21 d, with larger litter gains from 0 to 14 and 0 to 21 d when gestating sows had been fed the 16% protein and the High feed intake combination compared to the other sow treatment groups. From parity 2 to 5, litter weights and gains were similar for all treatment groups. This resulted in a three-way interaction response (P < .05) for these variables. These results suggest that primiparous sows required a greater gestation protein concentration and greater feed intake than generally recommended, but the 13% CP diet at the High feed intake was effective in older sows.