# Digestibility of Energy and Concentrations of Digestible and Metabolizable Energy in Pistachio Shell Powder and in Soybean Hulls Fed to Growing Pigs

## TL;DR

This study found that pistachio shell powder can be used as a fiber source in pig diets, providing similar energy value to soybean hulls.

## Contribution

The study provides new energy value data for pistachio shell powder as a feed ingredient for pigs.

## Key findings

- Pistachio shell powder had lower energy digestibility than corn but similar to soybean hulls.
- Pistachio shell powder provided 1778 kcal/kg of digestible energy on a dry matter basis.
- Pistachio shell powder increased fecal output due to its high fiber content.

## Abstract

Pistachio shells are a co-product of the pistachio industry and are often considered waste. Because pistachio production is increasing, identifying alternative uses for pistachio shells will improve sustainability. In this experiment, the hypothesis that the metabolizable energy in pistachio shell powder is not less than that in soybean hulls when fed to growing pigs was tested. Pigs were fed on a corn-based diet or diets containing pistachio shell powder or soybean hulls. Pistachio shell powder increased fecal output and had lower energy digestibility than corn, which was expected due to its high fiber content. However, the digestible and metabolizable energy in pistachio shell powder was not different from that in soybean hulls when included at 20% of the diet. These results indicate that pistachio shell powder may be used as a fiber ingredient in pig diets.

The hypothesis that the values obtained for the apparent total tract digestibility (ATTD) of energy and digestible energy (DE) and metabolizable energy (ME) in pistachio shell powder are not different from the values obtained for soybean hulls when fed to growing pigs. A basal diet containing corn, a diet containing corn and 20% pistachio shell powder, and a diet containing corn and 20% soybean hulls were formulated. Twenty-four growing pigs (initial body weight: 32.0 ± 1.7 kg) were allotted to the three diets in a randomized complete block design with eight pigs per diet. After a 7-d adaptation period, feces and urine were quantitatively collected for 4 days. The diets and feces were analyzed for dry matter, and all samples were analyzed for gross energy (GE). The results indicated that the ATTD of GE was greater (p < 0.05) for soybean hulls than for pistachio shell powder, but less (p < 0.05) than for corn. Pistachio shell powder provided less (p < 0.05) DE than corn (i.e., 1778 kcal/kg vs. 3787 kcal/kg; dry matter basis), but the DE in pistachio shell powder was not different from that in soybean hulls (i.e., 2010 kcal/kg; dry matter basis). In conclusion, pistachio shell powder can be used as an alternative ingredient in diets for growing pigs and provides 1778 kcal/kg of DE on a dry matter basis.