155 Effects of Ad Libitum or Restricted Feeding from 140 to 200 Days of Age on Removal Rate and Semen Production of PIC 800 Boars

Abstract Our objective was to determine the effects of ad libitum or restricted feeding PIC 800 boars from 140 to 200 d of age on removal rate and semen production. A total of 206 boars (141±1.5 d of age, 115±1.9 kg of body weight) were randomly allotted to 1 of 2 treatments that consisted of ad libitum feeding in pens (n = 119, 1.16 square meter floor space per boar) and restricted feeding with 2.3 kg/d in crates (n = 87, 1.05 square meter floor space per boar). All boars were fed a common diet that was formulated to have 2300 Kcal of NE/kg and 0.61% of standardized ileal digestible lysine. The 2 different feeding regimens were applied for approximately 58 d, with boars being individually weighed at approximately 140 and 200 d of age. Boars were then shipped to commercial boar studs where the removal and semen production data were collected. Data were analyzed using a generalized linear mixed model in R, and individual boar was considered the experimental unit. The feed intake of ad libitum fed boars were predicted to be 3.6 kg/d according to previously published models (Lu et al., 2021). At 200 d of age, restricted fed boars had reduced final body weight (143 and 186 kg, P < 0.001) and average daily gain (492 and 1,212 g/d, < 0.001) compared with those fed ad libitum. By d 450 of age, boars that were restricted fed had improved survival probability (78% and 56%, P = 0.002), and reduced removal probability due to structure reasons (9% and 26%, P = 0.017). The probability of the collected semen to be used was not affected by treatment (98.1 and 98.9%, P = 0.112). In the current experiment, restricted feeding from 140 to 200 d of age reduced growth rate of boars, increased their subsequent survival probability, but did not impact semen production.