Ileal Digestibility of Amino Acids in Pistachio Blanks and Growth Performance of Weanling Pigs Fed Diets Containing Pistachio Blanks as a Source of Fiber

Two experiments were conducted to determine the amino acid (AA) digestibility of pistachio blanks and to test the hypothesis that pistachio blanks can be used as a fiber source in diets for weanling pigs without affecting growth performance. In Exp. 1, two diets contained pistachio blanks or soybean meal (SBM) as the sole source of crude protein and AA were formulated. A nitrogen-free diet was also used. Nine barrows (body weight: 22.67 ± 0.93 kg) that had a T-cannula installed in the distal ileum were allotted to a triplicated 3 × 3 Latin square design with three diets and three periods. Ileal digesta were collected and analyzed for Cr and AA. In Exp. 2, four diets were formulated. A control diet containing corn and SBM, and three additional diets containing corn, SBM, and 5.0, 7.5, or 10.0% pistachio blanks at the expense of corn. A total of 160 pigs (body weight = 5.73 ± 0.33 kg) were allotted to the four diets using a randomized complete block design with 10 replicate pens per treatment and four pigs per pen. Pigs were fed in a 2-phase feeding program (5 to 20 kg) for 42 days, and average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F) were calculated. Fecal samples were collected in phase 2 for dry matter analysis. In both experiments, data were analyzed using the MIXED procedure in SAS, with diet as the fixed effect and block as the random effect. In Exp. 2, polynomial contrasts were used to test linear and quadratic effects of increasing pistachio blanks in the diets. Results of Exp. 1 indicated that the standardized ileal digestibility (SID) of crude protein and most AA were not different between pistachio blanks and SBM. However, the SID of Arg, His, Lys, and Met was greater (P < 0.05) in SBM than in pistachio blanks (Table 1). In Exp. 2, ADFI, G:F, and final body weight were not affected by dietary treatments throughout the experimental period (Table 2). However, ADG tended to decrease and then increase (quadratic, P < 0.10) as the inclusion of pistachio blanks in the diet increased. Likewise, fecal dry matter tended to reduce and then increase (quadratic, P < 0.10) as pistachio blanks inclusion in the diet increased. In conclusion, pistachio blanks provided amino acid digestibility values comparable to SBM for most amino acids. Additionally, inclusion of up to 10% pistachio blanks in diets for weanling pigs did not negatively affect growth performance or fecal dry matter, indicating that pistachio blanks can be used as a potential alternative fiber source in nursery pig diets without a negative effect on nutrient utilization or growth.