Performance and carcass characteristics in fattening lambs feed diets with different levels of pistachio by-products silage with wasted date

• Pistachio by-product (PBP) was ensiled with wasted date and used in lambs diet.
• Ensiling PBP with wasted date decreased total tannins and phenolic compounds.
• Adding pistachio by-products silage with wasted date (PBSWD) in diet increased DMI.
• Feeding 21% PBSWD increased performance of fattening lambs.
• PBSWD can be used up to 21% as a proper alternative feed in lambs diet.

Forty Kermani fattening male lambs (21 ± 1.4 kg body weight (BW) and six months old) were assigned to a completely randomized design to determine the effects of feeding pistachio by-products silage with wasted date (PBSWD) on dry matter intake (DMI), live weight gain, feed conversion and carcass characteristics. Two thousand kg of fresh pistachio by-products (PBP) were mixed thoroughly with 400 kg Mazafati wasted date and ensiled for 2 months. Experimental diets were: (1) control (without PBSWD); (2) diet containing 7% PBSWD; (3) diet containing 14% PBSWD and (4) diet containing 21% PBSWD. All diets were formulated to contain 60% concentrate and 40% forage (dry matter (DM) basis). The lambs were divided into four equal groups and fed the diets for a 90-day experimental period. At the end of the experiment, all animals were slaughtered on the same day. Ensiling of PBP with wasted date increased the DM and metabolisable energy (ME), but decreased (P < 0.05) the percentages of crude protein, ether extract, total tannins and phenolic compounds. Lambs fed the 14 and 21% PBSWD diets had more (P < 0.05) DMI than those fed control diet. Feeding 21% PBSWD increased (P < 0.05) final BW, weight gain, the weights of warm and cold carcass, liver, loin, lean meat, reproductive system and small intestine, and the eye muscle area,. Lambs fed 21% of PBSWD had higher (P < 0.05) back fat depth than lambs fed control diet. Results showed that feeding 21% PBWDS to fattening lambs increased their feedlot performance and lean meat yield.