Growth Performance, Eating Behavior, Digestibility, Blood Metabolites, and Carcass Traits in Growing-Finishing Fat-Tailed Lambs Fed Different Levels of Dietary Neutral Detergent Fiber with High Rumen Undegradable Protein

This study was conducted to investigate the effect of decreasing concentrations dietary neutral detergent fiber (NDF) at high rumen undegradable protein (RUP) on performance, digestibility, chewing activity, blood attributes, and carcass characteristics in 32 weaned male Afshari lambs (90 days age; 26 kg initial body weight; BW). Dietary metabolic energy (ME) increased from 10.6–11.5 11.8 MJ/kg dry matter (DM) by replacing alfalfa hay with grain achieve NDF 270, 245, 220 g/kg DM, respectively, 66.6 DM RUP. The control (CON) diet contained 10.9 ME, 270 59.6 RUP basis. Rations containedsimilar crude (CP, 160 DM). Lambs were slaughtered after a 56-d feeding period. increase had no BW average daily gain (ADG) but tended decrease apparent digestibility CP significantlydecreasedplasma urea concentration, content. Other or unchanged. Decreasing did not result adverse effects BW, ADG, length, withers height, CP, BFT, decreased intake (1539 vs. 1706 g/d) feed conversion ratio (FCR; 4.33 5.39) compared CON. Gradual reduction physically effective affecteating, ruminating times. Plasma glucose concentration greater for NDF220 than three other treatments (p = 0.015).Slaughtering traits affected treatment except hot weight, which NDF245 NDF270 0.021). meat versus CON (167 152 g/kg). Quadratic occurred ether extract (highest NDF220) fat-tail weight NDF245). In conclusion, results showed that increasing proportion within improves accretion. does impair eating behavior FCR 3-month-old fat-tailed lambs.