Fattening performance and carcass characteristics of lambs fed diets with different shares of non-degradable protein

Abstract

The effects of the level of non-degradable protein in diet on fattening performance and carcass characteristics of intensively fattened lambs are presented in the paper. The aim of this study was to determine the optimal level of non-degradable protein in the diet of weaned lambs fattened intensively. The experiment was conducted on 60 lambs of MIS population weaned at 60 days of age, divided into three groups. The effect of the use of three concentrated mixtures which differed in terms of the share of non-degradable protein at the rumen level was studied: 43% (I), 51% (II) and 58% (III). The average daily gain of lambs included in the treatments I : II : III was 0.169 : 0.205 : 0.227 kg, respectively. Conversion of dry matter (kg/kggain) on analogue treatments was 4.54 : 3.71 : 3.30; energy (MJ NEM/kg): 33.77 : 29.37 : 26.25; total protein (g/kg): 732 : 596 : 549. Values of yield of warm carcass with offal, observed per treatments I : II : III were as follows: 58.70 : 58.02 : 57.42%. Meat yield of category I (thigh, loin) on analogue treatments amounted to 37.27 : 37.35 : 37.51%, category II (back, shoulder, neck) 33.9 : 32.67 : 32.83% and category III (chest with a forearm and shanks): 27.78 : 29.59 : 29.10%. The ratio of muscle and bone tissue in the treatments with 48 : 51 : 58% non-degradable protein was 2.5:1; 2.9:1; and 2.8:1. This research has shown that the best fattening performance was achieved by lambs on treatment with 58% RUP while meat yield and morphological composition of the carcass side were not under significant influence of the studied treatment.