Effect of Dietary Crude Protein on Animal Performance, Blood Biochemistry Profile, Ruminal Fermentation Parameters and Carcass and Meat Quality of Heavy Fattening Assaf Lambs

Abstract

Thirty Assaf male lambs (30 ± 1.9 kg of body weight) were allocated to three groups fed diets differing in their crude protein (CP) contents (low protein (LP), 134 g CP/kg dry matter (DM); medium protein (MP), 157 g CP/kg DM; and high protein (HP), 173 g CP/kg DM) to test the effect of dietary protein content on animal performance, rumen function, animal health, and carcass and meat quality. Feed intake was recorded daily, and animals were weighed every second week. Lambs were blood-sampled to determine their acid–base status and biochemical profile. After 70 days of trial, lambs were slaughtered, and the ruminal content was collected to assess ruminal fermentation. Finally, carcass and meat quality were evaluated. Dry matter intake and average daily gain increased (p < 0.05) when increasing the level of dietary CP. There were not significant differences (p > 0.05) in the evaluated parameters in the rumen fluid of lambs. There were not significant differences in carcass or meat quality (p > 0.05) and in those parameters related to blood acid–base status. Several biochemical parameters showed differences depending on diet CP level (urea, protein, albumin, glucose, and calcium; p < 0.05). Feeding costs calculated in relation to cold carcass weight decreased when dietary CP decreased. The results suggested that a dietary protein content greater than 157 g/kg DM would be required to maximize growth performance in Assaf male fattening lambs under 50 kg of body weight. However, a protein content beyond that level was not found to improve either carcass or meat quality and could worsen profitability.

Effect of Different Protein Levels on Growth Performance, Carcass Trait, Digestibility and Some Blood Bieochemical Parameters in Awassi Lambs

“…Or may be this result is due to the highest bioavailability of nutrient by balanced energy and protein levels on the treatments (13). This finding is in accordance with those reported in sheep (10,29), as well as in goat (2, 22, 13, 27).…”

“…However, blood urea increased by increasing protein level but the increase was not significant. Similar results have been reported by other researchers (12,15,21,29,34,35).…”

Productivity and carcass characteristics of lambs fed fibrous agricultural wastes to substitute grass

“…[ 26 ] in thin-tailed sheep. The previous studies reported that the dressing percentages of different lamb breeds varied from 39% to 51% [ 21 , 25 , 26 , 29 , 30 ]. Valizadeh et al .…”

“…The carcass weights obtained in this study were similar to those reported by Setyaningrum et al [26], where Indonesian thin-tailed sheep weighing 17.5-18.8 kg produced 7.7-8.5 kg carcasses. Other studies reported that lamb carcass weights varied from 15.3 kg to 26.1 kg when originating from a slaughter weight of 34.3 kg-54.1 kg [21,[27][28][29][30]. Forwood et al [30] reported that heavier live weights produced higher carcass weights and dressing percentages.…”

“…Dressing percentages in this study (40.03%) were similar to those reported by Setyaningrum et al [26] in thin-tailed sheep. The previous studies reported that the dressing percentages of different lamb breeds varied from 39% to 51% [21,25,26,29,30]. Valizadeh et al [31] showed that the heavier the body weight of the lamb, the higher its carcass percentage.…”