Bakery waste as a sustainable feed resource for growing Awassi lambs: Effects on growth performance, nutrient utilization, carcass traits, meat quality, and health indicators

Abstract

Background and Aim: Bakery waste (BAWA) represents a potentially economical and sustainable alternative feed resource for ruminant production, particularly in regions where conventional feed ingredients are costly or scarce. This study evaluated the effects of dietary BAWA inclusion on nutrient intake and digestibility, growth performance, nitrogen (N) balance, economic efficiency, carcass characteristics, meat quality, fatty acid (FA) composition, and blood biochemical indicators in growing Awassi lambs. Materials and Methods: Twenty-four male Awassi lambs (initial body weight, 17.33 ± 0.821 kg; age, 75 ± 1.5 days) were randomly allocated to three dietary treatments (n = 8/group): control (CON; 0 g/kg BAWA), BAWA100 (100 g/kg BAWA), and BAWA200 (200 g/kg BAWA) on a dry matter (DM) basis. The 73-day experiment comprised 10 days of adaptation and 63 days of data collection. Nutrient intake, growth performance, feed efficiency, and feeding costs were determined. Five lambs per group were used for digestibility and N balance assessment. Carcass characteristics, meat quality, FA composition, and serum biochemical indicators were also evaluated. Results: BAWA100 and BAWA200 increased DM, crude protein (CP), and metabolizable energy intake compared with CON (p < 0.02). BAWA200 increased final body weight, total gain, and average daily gain and improved feed efficiency (p ≤ 0.007). The cost of gain was lower with BAWA200 (p < 0.001). DM and CP digestibility increased with BAWA200, while N retention improved with both BAWA treatments (p < 0.05). Fasting live weight, hot and cold carcass weights, and carcass cut weights were greater with BAWA200 (p ≤ 0.03). Dietary BAWA did not adversely affect meat quality or FA composition. Most serum biochemical indicators remained unaffected, whereas aspartate aminotransferase was numerically lower (p = 0.051) and alanine aminotransferase activities were lower in BAWA-fed lambs (p ≤ 0.05). Conclusion: Dietary inclusion of BAWA, particularly at 200 g/kg DM, improved growth performance, nutrient utilization, N retention, carcass yield, feed efficiency, and economic outcomes without compromising meat quality, FA composition, or health indicators. BAWA can therefore serve as a practical alternative to conventional concentrate ingredients in growing Awassi lamb diets while supporting more economical and sustainable small-ruminant production. Keywords: Awassi lambs, bakery waste, carcass traits, feed efficiency, growth performance, meat quality, nutrient digestibility, sustainable feeding.