Effect of soluble and insoluble dietary fiber on embryo survival and sow performance.

Two experiments were conducted to evaluate the effects of soluble (SF) and insoluble (ISF) dietary fiber during gestation on embryo survival and sow performance. In Exp. 1, 43 gilts were assigned randomly to 1 of 4 experimental diets: a corn-soybean meal control (C; 1.16% SF, 9.98% ISF); a 30% oat bran high in SF (HS; 3.02% SF, 10.06% ISF); a 12% wheat straw diet high in ISF (HIS; 1.08% SF, 18.09% ISF); and a 21% soybean hull diet (HS + HIS; 2.46% SF, 24.55% ISF). Gilts were fed the experimental diets based on their initial BW to meet their daily nutrient requirements. At estrus, gilts were inseminated artificially 3 times using pooled semen. Reproductive tracts were harvested 32 d postmating (range = 28 to 35 d). Statistical analysis of data included the effects of diet with days of gestation as a covariate. There were no differences in ovulation rate among gilts fed the experimental diets (avg. = 14.1). Number of live embryos was less for HIS and HS + HIS gilts compared with C and HS (9.9 and 9.1 vs. 11.9 and 10.6, respectively; P < 0.05). Total embryo survival rate (P < 0.05) was less for gilts fed HS + HIS compared with those fed the C and HS diets. These results suggest that high dietary ISF might decrease the total embryo survival rate without affecting ovulation rate. In Exp. 2, 716 sows were used in 3 concurrent trials. In trial 1, diets included a corn-soybean meal control (C; 0.43% SF, 10.50% ISF; n = 122) or a 31% oat bran diet (HS; 1.93% SF, 8.87% ISF; n = 124). In trial 2, diets included a C (n = 97) or a 13% wheat straw diet (HIS; 1.10% SF, 17.67% ISF; n = 119), and in trial 3 sows were fed a C (n = 123) or a 21% soybean hull diet (HS + HIS; 1.50% SF, 17.77% ISF; n = 131). All diets were offered to sows beginning 2 d postmating. All sows had ad libitum access to a standard lactation diet. Statistical analysis included the effects of diet, parity group, genetic line, and season as well as their interactions. The inclusion of SF and ISF in gestation diets did not affect litter size. Sows fed the HS + HIS diet had a greater ADFI and lost less BW during lactation (P < 0.01) than sows fed C. Under the conditions of this study, feeding gestating sows increased levels of SF and ISF from d 2 after breeding to d 109 of gestation did not increase litter size.

Effect of soluble and insoluble fiber on energy digestibility, nitrogen retention, and fiber digestibility of diets fed to gestating sows.

Twenty-four sows (12 nulliparous, 12 multiparous) were used to determine soluble fiber (SF) and insoluble fiber (ISF) effects on energy digestibility, N balance, and SF and ISF digestibility. Experimental diets included a corn-soybean meal control (C; 1.20% SF, 9.78% ISF), a 34% oat bran diet high in SF (HS; 3.02% SF, 10.11% ISF), a 12% wheat straw diet high in ISF (HIS; 1.11% SF, 17.86% ISF), and a 16% sugar beet pulp diet (HS + HIS; 2.32% SF, 16.08% ISF). Sows were assigned randomly to diets within parity group and individually fed to meet their energy requirements according to the NRC model assuming 10 pigs per litter and 40 kg of gestation gain. Total feces and urine were collected in 5-d periods at wk 5, 10, and 14 of gestation. There were no interactions between dietary treatments and parity group for any of the response criteria evaluated. Dietary energy digestibility was greatest (P < 0.01) for females fed C (87.9%) and HS (89.3%) diets compared with females fed diets high in ISF (HIS, 82.9; HS + HIS, 86.8%). Energy digestibility was not affected by stage of gestation. Dietary N digestibility was similar between C and HS (86.1 and 86.2%) but greater (P < 0.01) than HIS and HS + HIS (82.8 and 82.8%, respectively). Nitrogen digestibility declined (P < 0.05) as gestation progressed for sows fed HS only. Nitrogen retention as a percentage of N intake was not affected by diet (C, 51.8; HS, 44.0; HIS, 42.0; HS + HIS, 48.6). Soluble fiber digestibility was different (P < 0.01) among experimental diets (C, 85.8; HS, 89.5; HIS, 77.7; HS + HIS, 80.3%). Sows fed HS + HIS (61.8%) and HS (58.4%) had greater (P < 0.05) ISF digestibility than sows fed C (53.5%), whereas sows fed HIS (38.3%) had lower (P < 0.01) ISF digestibility than sows fed the other experimental diets. Greater digestibility of dietary energy (87.1 vs. 86.2%; P < 0.05), N (85.7 vs. 83.2%; P < 0.01), and ISF (54.5 vs. 51.2%; P < 0.06) was observed in multiparous vs. nulliparous sows. In conclusion, increased intake of ISF decreased energy digestibility, whereas increasing SF intake improved energy digestibility. Diet had no effect on N retention. Insoluble fiber digestibility improved when SF intake increased, suggesting that knowledge of specific dietary fiber components is necessary to accurately predict effects of dietary fiber on digestibility. Multiparous sows demonstrated a greater ability to digest fibrous diets than nulliparous sows.