Soybean hull inclusion on gilt growth and first parity total born

Four thousand three hundred and forty-six gilts from 10 gilt developer rooms (DNA Line 241, DNA Genetics, Columbus, NE) were weaned at ∼21 days and assigned to either a control (CON) diet based on corn and soybean meal or a slow growth (SG) diet containing increasing levels of soybean hulls (up to 50% soybean hulls) starting at approximately 25 kg of body weight to evaluate if feeding increasing levels of soybean hulls (dietary fiber) would reduce gilt growth rate and improve first parity performance. Each room was an experimental unit. Feed and water were provided ad libitum. Growth, puberty indicators, and reproductive traits were assessed through first parity. Subsets of gilts were vulva scored (day 111 of age; 150 gilts per treatment), blood was sampled for hormone analysis (days 150 and 164 of age; 40 gilts per treatment), and evaluated by ultrasound for back fat (BF) and loin depth (LD). Data were analyzed in SAS 9.4 using the GLIMMIX procedure, with cohorts as the experimental unit. Gilts fed the CON diet were heavier (102.2 vs. 94.8 ± 2.26 kg; P < 0.01), had wider vulvas, and greater back fat (15.1 vs. 12.5 mm ± 0.28; P < 0.01) compared to SG gilts. Loin depth did not differ between treatments. Age at first breeding was slightly younger for CON (227.7 vs. 231.8 ± 4.09 days; P = 0.44), though not significant. Total pigs born (15.0 and 14.8± 0.21 pigs/sow, respectively) and weaned (13.0 and 12.9 ± 0.24 pigs per sow, respectively) at first parity were unaffected by diet. Feeding soybean hulls to growing gilts reduced growth rates and back fat delaying puberty onset without impacting first-parity total born and pigs weaned performance. These findings suggest soybean hulls can be a tool for managing gilt growth rates without compromising productivity.