Pistachio by-product as a forage source for ruminant nutrition: A review (Part A: Reservation, chemical composition, feed intake, performance, and digestibility)

Pistachio farming is a main agricultural enterprise in central Iran and pistachio by-product are produced during the de-hulling of pistachio nuts after harvesting. This by-product contains varying amounts of soft external hull, twigs, leaves and kernel and bony shells. The present paper aims to sum up the literature exists on the methods of processing and storage, chemical composition, the appropriate levels of pistachio by-product consumption for livestock and its effects on growth performance and nutrient digestibility in ruminants. This by-product has a good potential for use in ruminant nutrition as a low price feed. Ensiling is the best method for long time preservation of this by-product as storage is difficult owing to its high moisture content; however, the addition of 1.5% molasses and a maximum of 0.5% urea are effective in increasing the quality of pistachio by-product silage. The dry matter (DM), organic matter, crude protein, NDF, ADF, phenolic compounds and total tannin in the dry pistachio by-product have been reported to be 93.91, 83.84, 11.81, 30.27, 22.12, 10.38 and 6.16%, respectively. The average dry matter digestibility of pistachio by-product ranged from 56.5 to 52.0% of DM. This review evaluates pistachio by-product relative to their nutrient composition, content of secondary compounds, and their impact on feed intake, digestibility, microbial protein synthesis and animal performance. Possible reasons and implications of these results to use pistachio by-product as a feed were discussed.