Olive leaves as alternative feed for finishing lambs: evaluation of feed intake, nutrients digestibility, growth performance, and carcase quality

Figures & data

Table 1. Ingredients and chemical composition of diets fed to Awassi lambs.

Item	Diet^a
	CON	OL50	OL100
Ingredients (g/kg DM)
Barley	540	548	560
Soybean meal	190	182	10
Wheat straw	250	200	150
Olive leaves^b	0	50	100
Salt	10	10	10
Limestone	09	09	09
Vitamin–mineral premix^c	01	01	01
Cost (US$/1000 kg)^d	405	381	359
Nutrients
Dry matter, g/kg	918	914	906
Crude protein, g/kg DM	160	161	160
Neutral detergent fibre, g/kg DM	312	293	275
Acid detergent fibre, g/kg DM	133	125	117
Ether extract, g/kg DM	10	13	16
Metabolisable energy, Mcal/kg	2.3500	2.4200	2.4800

^aDiets were (1) no olive leaves (CON), (2) 50 g/kg olive leaves (OL50), and (3) 100 g/kg olive leaves (OL100).

^bContained: 887, 88, 294, 219, 61 dry matter, crude protein, neutral detergent fibre, acid detergent fibre and ether extract, respectively.

^cComposition per kg contained: vitamin A, 600,000 IU; vitamin D3, 200,000 IU; vitamin E, 75 mg; vitamin K3, 200 mg; vitamin B1, 100 mg; vitamin B5, 500 mg; lysine, 0.5%; DL-methionine, 0.15%; manganese oxide, 4000 mg; ferrous sulphate, 15,000 mg; zinc oxide, 7000 mg; magnesium oxide, 4000 mg; potassium iodide, 80 mg; sodium selenite, 150 mg; copper sulphate, 100 mg; cobalt phosphate, 50 mg; dicalcium phosphate, 10,000 mg.

^dCalculated based on ingredients prices during 2022.

DM: Dry matter.

Table 2. Effects of olive leaves (OL) feed on nutrient intakes and growth performance of Awassi lambs.

Item	Diet^a
	CON	OL50	OL100	SE^b	p value
Nutrient intake, g/d
Dry matter	957b	976a	985a	2.2400	.0030
Crude protein	153c	158a	156b	0.4140	.0020
Neutral detergent fibre	299a	288b	268c	0.6610	<.0001
Acid detergent fibre	127a	123b	114c	0.2820	<.0001
Ether extract	9.7000c	12.900b	15.8000a	0.0290	<.0001
Metabolisable energy, Mcal/d	2.2500c	2.3800b	2.4200a	0.0054	<.0001
Initial weight, kg	17.8000	17.7000	17.3000	0.9400	.9300
Final weight, kg	31.0000	31.8000	30.4000	1.2000	.7000
Total gain, kg	13.2000	14.1000	13.1000	0.6800	.4800
Average daily gain, g/d	220	235	218	11.4000	.4800
Feed conversion ratio	4.3600	4.1900	4.5200	0.1870	.5200
Cost ($US/kg gain)	1.7700a	1.5900b	1.6200b	0.0310	.0300

a, b, c within a row, means without a common letter differ (p ≤ .05).

^aDiets were (1) no olive leaves (CON), (2) 50 g/kg olive leaves (OL50), and (3) 100 g/kg olive leaves (OL100).

^bSE: standard error.

Table 3. Effects of olive leaves (OL) feed on nutrient in vivo digestibility and N balance of Awassi lambs.

Item	Diets^a
	CON (n = 4)	OL50 (n = 4)	OL100 (n = 4)	SE^b	p value
Digestibility coefficients
Dry matter	77.000	75.700	77.100	2.4300	.900
Crude protein	76.000	75.000	78.200	3.2700	.780
Neutral detergent fibre	61.500	59.200	58.700	4.7800	.910
Acid detergent fibre	51.800	47.300	46.000	6.1800	.800
Ether extract	66.600	66.500	72.000	9.2900	.880
N balance
N intake, g/d	23.100	25.900	26.600	0.8700	.090
N in faeces, g/d	5.550	6.330	5.830	0.759	.630
N in urine, g/d	4.530	3.880	4.840	0.419	.310
N retained, g/d	13.020	15.670	15.970	1.334	.330
Retention, %	56.200	60.300	59.900	3.930	.740

^aDiets were (1) no olive leaves (CON), (2) 50 g/kg olive leaves (OL50), and (3) 100 g/kg olive leaves (OL100).

^bSE: standard error.

Table 4. Effects of olive leaves (OL) feed on the carcase, non-carcase components, carcase cut weights, and loin cut tissues percentages of Awassi lambs.

Item	Diets^a
	CON n = 12	OL50 n = 12	OL100 n = 12	SEb	p value
Fasting live weight (kg)	28.200	30.400	29.200	1.260	.470
Hot carcase weight (kg)	13.600	14.300	14.200	0.640	.710
Cold carcase weight (kg)	12.400	13.400	13.300	0.620	.460
Dressing percentage	43.600	44.000	45.300	0.810	.330
Non-carcase components (kg)^c	1.200	1.300	1.200	0.052	.280
Carcase cut weights (kg)^d	11.340	12.020	11.350	0.520	.570
Loin weight, g	299	351	311	27.800	.400
Intermuscular fat (g)	6.800	8.500	7.300	1.240	.610
Subcutaneous fat (g)	24.600	26.000	24.600	4.240	.960
Total fat (%)	10.100	9.200	10.100	0.840	.690
Total lean (%)	50.400	52.000	53.000	2.120	.520
Total bone (%)	30.100	28.500	30.200	2.280	.800
Meat to bone ratio	2.670	1.910	1.830	0.582	.510
Meat to fat ratio	5.470	6.060	5.750	0.529	.730

^aDiets were (1) no olive leaves (CON), (2) 50 g/kg olive leaves (OL50), and (3) 100 g/kg olive leaves (OL100).

^bSE: standard error.

^cNon-carcase components (Heart, liver, spleen, kidney, lungs, and trachea).

^dCarcass cut (shoulder, racks, loins, and legs).

Table 5. Effects of olive leaves (OL) feed on linear dimensions of the longissimus dorsi muscle in Awassi lambs.

Item	Diets^a
	CON (n = 12)	OL50 (n = 12)	OL100 (n = 12)	SE^b	p value
Leg fat depth (L3) (mm)	1.630	1.920	1.810	0.286	.780
Tissue depth (GR) (mm)	8.030	8.370	7.630	0.504	.550
Rib fat depth (J) (mm)	1.690	1.910	1.540	0.215	.450
Eye muscle width (A) (mm)	48.890	49.980	48.420	1.198	.640
Eye muscle depth (B) (mm)	20.060	21.780	20.020	0.755	.200
Fat depth (C) (mm)	1.110	1.090	1.080	0.075	.970
Shoulder fat depth (S2) (mm)	1.370	1.280	1.250	0.149	.780

^aDiets were (1) no olive leaves (CON), (2) 50 g/kg olive leaves (OL50), and (3) 100 g/kg olive leaves (OL100).

^bSE: standard error.

Table 6. Effects of olive leaves (OL) feed on the physicochemical properties of the longissimus dorsi muscle in Awassi lambs.

Item	Dietsa
	CON (n = 12)	OL50 (n = 12)	OL100 (n = 12)	SE^b	p value
pH^c	5.800	5.810	5.790	0.006	.080
Cooking loss (%)	40.450	39.640	39.570	0.529	.440
Water holding capacity (%)	20.380	23.730	21.850	0.994	.080
Shear force (kg/cm^2)	5.580	6.020	4.740	0.439	.130
Colour coordinates
L* (whiteness)	28.200	28.110	28.800	0.433	.490
a* (redness)	1.780	1.870	1.820	0.066	.630
b* (yellowness)	19.790	19.920	20.030	0.205	.670

^aDiets were (1) no olive leaves (CON), (2) 50 g/kg olive leaves (OL50), and (3) 100 g/kg olive leaves (OL100).

^bSE: standard error.

^cpH measured after thawing.

Data availability statement

The original data of the paper are available upon request from the corresponding author.