Effect of Simulated Outdoor Rearing on Growth Performance, Health, Blood Minerals, and Complete Blood Cell Count in Wean-to-Finish Pigs.

Sows (PIC-29) were blocked by 110d BW and parity to test the effect of an enriched environment during lactation on health, growth performance, blood minerals and blood cell counts of offspring. Entire litters (10 replicates/treatment) with more than 8 pigs/litter were assigned to: a) PC, devoid of topsoil;, b) ITS, irradiated topsoil (1x10⁶ CFU/ml);c) non-irradiated topsoil (TS, 6x10⁶CFU/ml) from d4 postpartum to end of lactation (d21) by allowing free access to an empty pan or pans contained approximately 1 kg of daily-renewed soil located in the farrowing crate assessable only to piglets. At weaning, 4 middle BW littermates were penned together from nursery through finishing, and feed disappearance and BW were recorded at the end of each feeding phase to calculate ADG, ADFI, and G:F. Real time ultrasound images were collected at the end of each grow-finish period. Pigs were fed common antibiotic-free nursery diets and corn-SBM-DDGS finishing diets. Blood samples were collected at d 4, 21 and 69 to determine blood cell counts and mineral composition. Data were analyzed with PROC Mixed of SAS, with lactation treatments as the lone fixed effect. Chi-Square was used to test frequency of binary variables. Pigs exposed to both TS and ITS during lactation had a reduced scour rate and medical treatment requirement when compared to PC, and TS pigs were more efficient during the overall nursery than either PC or ITS pigs, which indicates possible efficacy of live microorganisms. Results of this study confirms the enhancement in growth performance in pigs exposed to non-irradiated topsoil during the lactation period which suggest that soil exposure during lactation may explain improved performance and health status of outdoor-reared pigs in previous studies.

Table 1 Effect of simulated outdoor rearing on performance in wean-to-finish pigs

	PC	ITS	TS	P - value
ADG, nursery phase 1, kg/d	0.017x	0.050xy	0.073y	0.06
Gain to feed ratio:
Nursery phase 1	-0.057a	0.214ab	0.345b	0.03
Nursery overall	0.532a	0.558a	0.637b	0.01
Finisher phase 3	0.277x	0.295xy	0.369y	0.10
Longissimus area, end of finisher 3, cm2	43.0x	46.6xy	47.3y	0.08
Hot carcass weight, kg	92.57	95.26	96.74	NS
Lean, %	52.64	52.67	52.76	NS
Scour, %	12.12y	5.05x	5.05x	0.10
Medical treatments, %	10y	3x	4x	0.07
Lymphocyte, %	41.45b	40.88b	35.03a	0.03
MCH1, pg	14.38a	15.68b	15.01ab	0.01
MCHC2, g/dl	27.98a	29.99b	28.93ab	< 0.01
P, mg/kg	14.92y	14.00xy	13.63x	0.07
K, mg/kg	59.98y	58.29xy	53.84x	0.08

1. Mean corpuscular hemoglobin: hemoglobin amount per red blood cell
2. Mean corpuscular hemoglobin concentration: hemoglobin amount per unit of red blood cell