Influence of varied sprouted barley feeding levels on carcass traits, meat quality, and fatty acid profile of lambs

Abstract

The aim of this study was to evaluate the carcass characteristics, meat quality and fatty acid profile of lambs fed different levels of sprouted barley (SB) compared to a control group fed a diet based on barley grain and alfalfa hay. Forty-five intact male Awassi lambs (3 months old) were included in the study and were fed for 75 days, divided equally into five feeding groups based on their average body weight. The groups were fed diets containing 25%, 50%, 75% and 100% SB replacing the control diet of barley grain and alfalfa hay (SB25, SB50, SB75 and SB100, respectively). The results showed that SB (SB25–SB75) had no effect on body weight gain while a significant gradual decrease in dry matter, crude protein and crude fat intake with the inclusion of SB (SB50–SB100). Higher rates of SB, especially 50%, 75% and 100%, resulted in a remarkable decrease in body wall fat. In addition, the treatment groups receiving SB50, SB75 and SB100 had a significantly lighter ultimate meat color compared to the control diet (p < 0.05). Interestingly, lambs fed SB25 resulted in the lowest saturated fatty acids and the highest mono-unsaturated fatty acids compared to the control group. In conclusion, partial replacement of the basal diet with SB can improve growth performance, carcass characteristics, body fat distribution and fatty acid profile of lambs. Therefore, further studies are needed to verify the optimal use of SB as one of the feeding systems to increase the nutritional requirements of growing lambs.

Keywords:

• Sprouted barley
• Awassi lambs
• meat quality
• fatty acids profile

REVIEWING EDITOR:

• Pedro Gonzalez-Redondo, Universidad de sevilla, Spain

SUBJECTS:

• Plant & Animal Ecology
• Zoology
• Botany
• Agriculture & Environmental Sciences

1. Introduction

In recent years, there has been a growing interest in improving production systems for fattening lambs, keeping in view their crucial role in ensuring food security, particularly in regions like the Middle East. The fattening lambs in these countries heavily depend on crops and their by-products such as cereals and roughage, which are susceptible to seasonal climatic changes, including rainfall (Alhidary et al., 2016). Currently, the livestock industry faces many challenges, including feed shortages, unaffordable prices, and wastage of water resources for growing crops used for lamb fattening (Fayed, 2011). Therefore, sustainable feed sources need to be evaluated as one of the strategies to overcome the challenges of reducing feed costs and increasing flock owners’ profitability while maintaining productive lamb efficiency, carcass characteristics, and meat quality (Safwat et al., 2014; Gómez-Cortés et al., 2019; Ferrinho et al., 2020). Improvements in feed quality and management have attracted much attention to optimize productivity and efficiency, as feed can account for up to 70% of the total cost of lamb production, and incomes along the chain are dynamic and often under pressure (Cabiddu et al., 2022).

Sprouted barley (SB) is one of the technologies for year-round production of green lambs feed, which is characterized by the fact that it requires less space and water to produce one ton compared to traditional agriculture (Cáceres et al., 2017). Hydroponic feeds such as SB can be an effective strategy for providing lambs feed in areas suffering from soil fertility and water scarcity, while maintaining the productive performance of the lambs (Arif et al., 2023). Due to the activity of hydrolytic enzymes produced during germination, SB is better digested than barley seeds (Lemmens et al., 2019). As a result, SB had a higher nutritional value of protein, fiber, fat, minerals and vitamins, while the content of dry matter (DM), starch and antinutrients was lower (Al-Saadi & Al-Zubiadi, 2016; Ikram et al., 2021). On the other hand, previous studies were conducted in which a high SB content had a negative effect on the performance indices of growing lambs because they consumed less DM compared to traditional feed (Muhammad et al., 2013; Farghaly et al., 2019). Lambs fed 62% SB had a positive affected body weight gain and feed intake compared to those fed the total mixed ration (Ata, 2016). The type of feed affects the carcass composition and meat quality of the lambs (Lee et al., 2008). However, it has been reported that replacing SB with a concentrate mixture (50:50) had no effect on carcass characteristics or body components of growing lambs (Devendar et al., 2020).

The limited research on the use of SB in lamb diets, particularly with respect to meat quality and fatty acid profile, necessitates an investigation of the effects of optimal replacement levels compared to lambs fed barley grain and alfalfa hay. Our previous studies have demonstrated that lambs fed SB have improved rumen ecosystem parameters and digestibility (Al-Baadani et al., 2022; Alharthi et al., 2022). This could be reflected in improvement of carcass characteristics, meat quality and fatty acid profile of growing lambs, which was also the hypothesis of this study.

The aim of this study was to evaluate the effects of different SB levels on carcass characteristics, meat quality and fatty acid profile of lambs compared to the usual diet of barley grain and alfalfa hay. The results of this study will help to support the development of more sustainable and efficient production systems for lambs.

2. Materials and methods

2.1. Lambs management, study design and feeding

All procedures in this study, including lambs’ husbandry, slaughter, and sampling, were approved according to the guidelines of the Scientific Ethics Committee of King Saud University, Saudi Arabia (KSU–SE-22–01). Forty-five healthy male lambs (Awassi) aged three months used for this study were purchased from commercial farms in Riyadh, Saudi Arabia, with an average body weight of 27.85 ± 2.50 kg and equal body condition score (condition 3; spine rounded and smooth) for 75 days as the experimental period. Lambs were isolated for 7 days immediately after their arrival at the study site after making sure that they were healthy. They were vaccinated against common diseases (enterotoxemia, septicemia and peste des petits ruminants) according to the guidelines of the Animal Resources Directorate of the Ministry of Environment, Water and Agriculture in the Kingdom of Saudi Arabia. The lambs were equally divided according to their average body weight into 45 individual pens (150 × 120 cm) in five different SB levels, with each group consisting of nine lambs and each lamb (pen) representing one experimental unit using a completely randomized design. The usual basal diet of barley grain and alfalfa hay (70:30) was replaced in the control diet by SB at levels of 25, 50, 75 and 100% (SB25, SB50, SB75 and SB100, respectively). The analysis of nutrients for each replacement level was performed in duplicate according to the Association of Official Analytical Chemists (AOAC, 2012). The feed ingredients and nutrient content of the control diet, SB (SB100) and replacement levels (SB25–SB75) are listed in Table 1. Sprouted barley (SB) was grown in hydroponics according to the technique described previously (Al-Saadi & Al-Zubiadi, 2016). After the seven-day growth period, the SB was air-dried overnight directly in the hydroponics chamber and then cut into 2 cm pieces and offered to the lambs according to the feeding levels. All lambs were given unlimited access to feed and water throughout the study.

Table 1. Feed ingredients and nutrient content of sprouted barley levels.

Feed ingredients, %	Sprouted barley levels (SB)
	Control	SB25	SB50	SB75	SB100
Barley	70.0	52.5	35.0	17.5	0
Alfalfa hay	30.0	22.5	15.0	7.5	0
Sprouted barley	0.0	25.0	50.0	75.0	100
Total	100	100	100	100	100
Nutrient analysis, % of DM*
DM	95.5	76.7	57.8	38.9	20.1
Crude protein	15.0	14.6	14.4	14.2	13.9
Neutral detergent fiber	34.2	35.0	30.3	31.0	36.9
Acid detergent fiber	19.8	18.2	16.0	17.6	16.8
Lignin	5.8	5.4	5.0	4.1	2.1
Non-fibrous carbohydrates	43.9	43.6	48.8	48.3	43.5
Fat	1.7	1.8	1.9	2.0	2.7
Ash	5.2	4.9	4.6	4.4	3.0
Calcium	0.6	0.6	0.5	0.4	0.2
Phosphorus	0.2	0.3	0.3	0.3	0.4
Magnesium	0.2	0.2	0.2	0.2	0.1
Potassium	1.5	0.4	1.2	1.0	0.5
Sulfur	0.2	0.2	0.2	0.2	0.2
Sodium	0.2	0.2	0.2	0.2	0.2
Zinc, ppm	33.0	37.0	39.0	41.0	70.0
Copper, ppm	5.0	7.0	6.0	5.0	6.0
Total digestible nutrients	80.0	81.8	84.3	82.5	83.4
Net energy, MJ/kg	7.72	7.91	8.09	7.91	8.00

* Nutrient analysis was performed in duplicate.

The groups were fed diets containing 25%, 50%, 75% and 100% sprouted barley replacing the control diet of barley grain and alfalfa hay (SB25, SB50, SB75 and SB100, respectively).

2.2. Calculation of general performance indices

All lambs were weighed twice (1 and 75 days) during the study period to calculate body weight gain (BWG) according to the formula described previously (Tánori-Lozano et al., 2022). $$\mathit{\text{BWG}}=\frac{\mathit{\text{Initial}}-\mathit{\text{final}}\mathit{\text{body}}\mathit{\text{weight}}}{\mathit{\text{Days}}}$$

During the study period, nutrient intake, including dry matter intake (DMI), crude protein intake (CPI), and crude fat intake (CFI) were determined using the following formula (Hassan & Almaamory, 2019): $$\mathit{\text{Nutrient}}\mathit{\text{intake}}=\frac{\mathit{\text{offered}}-\mathit{\text{rejected}}\mathit{\text{nutrient}}in\mathit{\text{take}}}{\mathit{\text{Days}}}$$

Finally, the nutrient conversion ratio was expressed using the following formula (Wu et al., 2021): $$\mathit{\text{Nutrient}}\mathit{\text{conversion}}\mathit{\text{ratio}}=\frac{\mathit{\text{daily}}\mathit{\text{nutrient}}\mathit{\text{intake}}}{\mathit{\text{daily}}\mathit{\text{weight}}\mathit{\text{gain}}}$$

2.3. Slaughter procedures and measurements

The slaughter process and sampling involved precise steps that were carried out within 24 h: After 75 days, all lambs were slaughtered for the feeding level (total = 45) according to standard commercial procedures at the slaughterhouse. Record live weight prior to slaughter after withholding feed and water from lambs for 12 h, in accordance with animal welfare legislation. Skin all lambs and remove the eviscerates, known as body components. The carcasses (without skin and digestive tract or internal organs) with tails were weighed at 15 min after slaughter (initial) to determine the hot carcass weight (Maggiolino et al., 2021). Empty body weight was calculated based on the difference between the slaughter live weight and the full gastrointestinal tract (stomach and intestines) (Bautista-Díaz et al., 2020). The relative weights of the body components (head, heart, lungs, liver, spleen, kidneys, genitals, tail, skin, gut fill, stomach empty and intestine empty) were calculated as a percentage based on the body weight (Wu et al., 2021). $$\begin{array}{l}\mathit{\text{The}}\mathit{\text{relative}}\mathit{\text{weights}}\mathit{\text{of}}\mathit{\text{the}}\mathit{\text{body}}\mathit{\text{components}}\\ =\frac{\mathit{\text{body}}\mathit{\text{components}}\mathit{\text{weight}}}{\mathit{\text{slaughter}}\mathit{\text{weight}}}\times 100\end{array}$$

The carcasses were chilled at 5 °C for 24 h (ultimate) to determine the cold carcass weight and chill shrink (hot carcass weight − cold carcass weight/hot carcass weight × 100). Finally, the carcass dressing percentage was expressed as percentage based on the slaughter live weight and empty body weight (Wu et al., 2021). $$\begin{array}{l}\mathit{\text{Carcass}}\mathit{\text{dressing}}pe\mathit{\text{rcentage}}\\ =\frac{\mathit{\text{hot}}\mathit{\text{carcass}}\mathit{\text{weight}}}{\mathit{\text{slaughter}}\mathit{\text{or}}\mathit{\text{empty}}\mathit{\text{weight}}}\times 100\end{array}$$

2.4. Depots measurements and wholesale cut percentage

Fat depot components such as back fat and body wall fat were recorded, while pericardial fat, Kidney knob and channel fat, omental fat, and mesenteric fat were expressed as a percentage based on live weight (Bautista-Díaz et al., 2020).

Carcasses were divided into two halves along the midline, and the right half of each carcass was divided into primary wholesale cuts, including shoulder, rack, loin, leg, and fore shank and breast. Each cut was weighed and reported as a percentage of the half carcass weight (Avendaño-Reyes et al., 2011). The fat, meat, bone, and trimmings of rack cut were separated by trained people and then weighted and expressed as a percentage of rack cut weight (Almeida et al., 2022). The area of the rib eye (12th and 13th ribs) was estimated by drawing an acetate sheet on the border of the eye rib, then removing it, coloring the area black, and scanning it with an electronic planimeter (Topcon KP-92N, USA) to calculate the outer limits of the longissimus dorsi (Khani et al., 2023).

2.5. Meat quality analysis

At 15 min and 24 h after slaughter (initial and ultimate), the pH and temperature in longissimus dorsi muscle on carcass and meat sample were measured using a digital pH meter (Hanna Instruments, 211, RI, USA) equipped with a puncture electrode and a thermometer (Luo et al., 2019). The instrumental color values including lightness, redness, and yellowing of carcasses (outer surface of the shoulder) and meat (longissimus dorsi cut) were measured at initial and ultimate stages using a digital colorimeter (Konica Minolta, CR -400- Japan). These values were then used to calculate color change [(Sqrt (lightness − 94.18) 2 + (redness − 0.43) 2 + (yellowness − 3.98) 2)], chroma [Sqrt (redness) 2 + (yellowness)2], hue angle [tan − (yellowness/redness)], and yellowness to redness ratio (Ekiz et al., 2020).

Longissimus dorsi muscle was collected, then cut and placed in polyethylene bags for analysis of meat quality parameters. The cooking loss (CL) was determined by cooking 100 g of the meat sample in an electric grill (Princess, 2321, Netherlands) while monitoring the temperature by inserting a thermal probe (Eco scan Temp JKT, Eutech Instruments) until an internal temperature of 70 °C was reached, which represents the end of the cooking process. The CL was calculated as follows: CL % = (initial weight − cooked weight) × 100/initial weight (Maggiolino et al., 2021).

Shear force (SF) and texture profile analysis (hardness, springiness, cohesiveness, chewiness, and resilience) were determined by cutting the cooked meat sample into longitudinal muscle fibers pieces (2 cm²) and measuring the force required to cut through the sample using a TA-HD Texture Analyzer (Stable Micro Systems Ltd., Godalming, UK) outfitted with a Warner–Bratzler attachment (Maggiolino et al., 2021).

Texture profile analysis:

• Hardness: The force required to compress the cooked meat sample by 50% of its original height (maximum force needed to compress the sample).

• Springiness: The distance that the cooked meat sample recovered after being compressed by 50% of its original height (the ability of a sample to recover to its original form after the removal of the compressing force).

• Cohesiveness: The amount of energy required to break the cooked meat sample into two pieces (ratio between the total energy required for the first and second compression).

• Chewiness: The sum of the hardness and cohesiveness of the cooked meat sample (springiness × hardness × cohesiveness).

• Resilience: The ability of the cooked meat sample to return to its original shape after being compressed by 50% of its original height (area of the first compression divided by area of the first compression).

Water holding capacity (WHC) was determined by the filter paper press method using a pressing machine with a force of 12 kg for 5 min and then reweighed. WHC was expressed as follows: WHC% = 100 − (weight of meat pressed before the press − weight of meat pressed after the press) × 100/weight of meat pressed before the press (De Palo et al., 2017).

Myofibril fragmentation index (MFI) was determined by homogenizing 4 g of longissimus dorsi muscle sample in 40 mL of buffer cold (4 °C) and then measuring the absorbance of the solution using a spectrophotometer analyzer (JENWAY, 6705, Stone, Staffs, UK) at 540 nm (Culler et al., 1978).

2.6. Fatty acid composition analysis

Meat samples from the longissimus dorsi muscle (100 g) were collected and frozen in polyethylene bags at −20 °C until the fatty acid profile was analyzed. The fatty acid profile of the meat was analyzed according to the previously described procedure (Tánori-Lozano et al., 2022; Luo et al., 2019). Briefly, each meat sample was homogenized and dried in a freeze dryer (Osterode am Harz, Germany), ground to powder and stored at −20 °C until fat extraction. The fat extraction was performed as described by the Association of Official Analytical Chemists (AOAC, 2012). To evaluate the fatty acid profile, 0.5 mL boron trifluoride was added to the fat extract, which was then heated at 100 °C for 5 min and cooled to room temperature. A mixture of hexane and NaCl sodium chloride (sigma-aldirch Santlouis, USA) (1:2) was added and centrifuged at 1,500 × g for 5 min at 4 °C (Universal 320, Andreas Hettich GmbH, Tuttlingen, Germany). The upper phase of the fatty acid methyl esters was isolated. The fatty acid methyl esters were analyzed by gas chromatography-mass spectrometry (Agilent Technologies, Palo Al-to, CA, USA). The fatty acid parameters were expressed as a percentage of the total fatty acid methyl esters identified.

2.7. Statistical analysis

The results obtained from this study for each parameter were examined by normality test (skewness, kurtosis, and boxplot) before data analysis process. The data were analyzed by one-way analysis of variance using the general linear models in Statistical Analysis System version 9.4 software (SAS Institute, 2008). The statistical model was performed using the following formula: $$\begin{array}{l}\text{Observation\hspace{0.17em}\hspace{0.17em}values\hspace{0.17em}\hspace{0.17em}}\left(Y\mathit{\text{ij}}\right)\\ =\mathit{\text{general}}\mathit{\text{mean}}\left(\mu \right)\\ +\mathit{\text{main}}\mathit{\text{effect}}\mathit{\text{of}}\mathit{\text{SB}}\left(\mathit{\text{SBi}};i=0,25,50,75,\hspace{0.17em}\mathit{\text{and}}100\text{\%}\right)\\ +\mathit{\text{experimental}}\mathit{\text{error}}\left(\mathit{\text{eij}}\right)\end{array}$$

A Duncan multiple range test was used to statistically compare of different levels for each parameter and considered as a statistical difference at the 5% probability level. The values of the different levels of SB were presented as means of the individual parameters together with the standard error of the mean (±SEM).

3. Results

3.1. General performance indices

The General growth performance of lambs fed SB was evaluated and summarized in Table 2. Replacing 25%–75% of the control diet with SB (SB25–SB75) had no effect on BWG but replacing 100% of the control diet with SB resulted in lower BWG compared to all groups (p = 0.009). Replacing 50%–100% of the control diet with SB (SB50–SB100) resulted in a gradual decrease in DMI, CPI and CFI compared to the control diet (p < 0.05). The nutrient conversion ratio of DM, crude protein (CP) and crude fat (CF) were not affected by SB compared to the control diet (p > 0.05).

Table 2. General growth performance of lambs fed sprouted barley.

Parameters^1	Sprouted barley levels (SB)
	Control	SB25	SB50	SB75	SB100	SEM^2	p-Value
BWG (g/day)	176^a	141^a	144^a	138^a	39^b	20.86	0.009
DMI (g/day)	1067^a	1026^ab	917^b	729^c	336^d	38.87	<0.0001
CPI (g/day)	160^a	150^a	132^b	104^c	47^d	5.31	<0.0001
CFI (g/day)	18^a	17^ab	15^b	12^c	6^d	0.57	<0.0001
Nutrient conversion ratio (g/g)
DM	6.89	7.84	6.85	6.88	8.81	0.99	0.681
CP	1.03	1.15	0.99	0.99	1.22	0.13	0.763
CF	0.11	0.13	0.12	0.11	0.15	0.02	0.618

For superscripts (a–e), the difference in the mean values within the rows for each SB level is considered significant if p < 0.05.

The groups were fed diets containing 25%, 50%, 75% and 100% sprouted barley replacing the control diet of barley grain and alfalfa hay (SB25, SB50, SB75 and SB100, respectively).

¹ BWG = body weight gain; DMI = dry matter intake; CPI = crude protein intake; CFI = crude fat intake.

² SEM = Standard error of means for diets effect.

3.2. Carcass measurements

Carcass characteristics and body components of lambs fed SB are presented in Table 3. Lambs fed 100% SB (SB100) had significantly lower live weight, empty weight, hot weight and cold weight than lambs fed the control diet (p < 0.05). Lambs fed SB100 also had significantly higher relative chill shrink, head and heart weights than lambs fed the control diet (p < 0.05). Relative genital weight was higher in lambs fed SB75 than in lambs fed the control diet and SB100, while it was not affected by SB25 and SB50 (p = 0.006). The relative weight of the tail decreased in lambs fed SB50 and SB100 compared to lambs fed SB25 and SB75, but not compared to the control diet (p = 0.034). In contrast, the relative weight of the dressing and other body components were not affected by SB (p > 0.05).

Table 3. Carcass traits and body components of lambs fed sprouted barley.

Parameters	Sprouted barley levels (SB)
	Control	SB25	SB50	SB75	SB100	SEM^6	p-Value
Carcass properties
Slaughter wt. (kg)	40.5^a	40.7^a	37.4^a	36.3^a	26.5^b	1.65	<0.0001
Empty body wt. (kg)^1	36.3^a	36.9^a	33.9^a	32.4^a	23.2^b	1.49	<0.0001
Hot carcass (kg)^1	19.0^a	19.4^a	17.1^a	17.5^a	12.0^b	0.97	<0.0001
Cold carcass (kg)^2	18.7^a	19.2^a	16.7^a	17.2^a	11.7^b	0.97	<0.0001
Chill Shrink%	1.77^b	2.00^b	2.21^b	2.27^b	2.97^a	0.21	0.006
Dressing % (SLW)^3	46.7	47.8	45.8	48.2	45.4	0.92	0.177
Dressing % (EBW)^4	52.1	52.7	50.5	54.1	51.9	1.11	0.261
Body components (%)^5
Head (skinned)	3.38^b	3.37^b	3.54^b	3.51^b	4.17^a	0.09	<0.0001
Heart	0.85^b	0.83^b	0.85^b	0.86^b	1.02^a	0.02	0.009
Lungs	2.68	2.39	2.32	2.24	2.33	0.22	0.702
Liver	4.01	3.46	3.39	3.62	3.65	0.27	0.570
Spleen	0.35	0.32	0.37	0.30	0.37	0.02	0.214
Kidneys	0.58	0.54	0.58	0.58	0.72	0.04	0.092
Genitals	0.75^b	1.02^ab	1.05^ab	1.07^a	0.46^c	0.09	0.006
Tail	11.24^ab	12.70^a	9.43^b	12.68^a	8.89^b	1.01	0.034
Skin	11.15	10.77	12.01	11.09	10.97	0.34	0.138
Gut fill	10.29	9.44	9.26	10.89	12.49	0.92	0.127
Stomach empty	3.27	3.60	3.82	3.87	3.48	0.18	0.171
Intestine empty	2.95	3.51	3.31	3.89	3.85	0.30	0.194

For superscripts (a–c), the difference in the mean values within the rows for each SB level is considered significant if p < 0.05.

The groups were fed diets containing 25%, 50%, 75% and 100% sprouted barley replacing the control diet of barley grain and alfalfa hay (SB25, SB50, SB75 and SB100, respectively).

¹ Empty body and hot carcass were weighted at 15 min after slaughter.

² Cold carcasses were weighted at 24 h after slaughter.

³ Dressing percentage was calculated based on slaughter live weight (SLW).

⁴ Dressing percentage was calculated based on empty body weight (EBW).

⁵ Body components were computed based on slaughter weight.

⁶ SEM = Standard error of means for diets effect.

3.3. Fat depots measurements

Body fat depots components of lambs fed SB are presented in Table 4. Back fat was significantly decreased in lambs fed 100% SB (SB100) and increased in lambs fed 25% SB (SB25) compared to other groups (p = 0.004). Body wall fat was significantly decreased in lambs fed 100% SB (SB100) and then 75% SB (SB75) compared to lambs fed the control diet and SB25 (p = 0.001). In contrast, other parameters of body fat depots, such as back fat, pericardial fat, kidney knob and channel fat (KKCF), omental fat, and mesentery fat, were not affected by SB (p > 0.05).

Table 4. Body fat depots components of lambs fed sprouted barley.

Parameters	Sprouted barley levels (SB)
	Control	SB25	SB50	SB75	SB100	SEM^2	p-Value
Back fat (mm)	2.525^b	3.595^a	2.476^b	2.533^b	1.778^c	0.23	0.004
Body wall fat (mm)	5.05^a	5.26^a	4.24^ab	3.89^bc	2.91^c	0.36	0.001
Pericardial fat%	0.38	0.31	0.29	0.37	0.37	0.03	0.308
KKCF%^1	1.27	1.04	1.14	0.97	1.06	0.11	0.402
Omental fat%	0.002	0.002	0.002	0.001	0.001	0.0004	0.347
Mesentery fat%	0.003	0.002	0.003	0.003	0.003	0.0004	0.595

For superscripts (a–c), the difference in the mean values within the rows for each SB level is considered significant if p < 0.05.

The groups were fed diets containing 25%, 50%, 75% and 100% sprouted barley replacing the control diet of barley grain and alfalfa hay (SB25, SB50, SB75 and SB100, respectively).

¹ KKCF = Kidney knob and channel fat.

² SEM = Standard error of means for diets effect.

3.4. Wholesale cut percentage

Primary wholesale cuts and rack physical separation of lamb carcasses fed sprouted barley are illustrated in Table 5. The relative weight of primary wholesale cuts, including shoulder (SB75–SB100) and leg (SB50–SB100), increased while that of rack (SB75–SB100) and loin (SB50–SB100) decreased compared to other groups (p < 0.05). The physical separation of rack, such as the relative weight of fat, was lower and that of bone higher in SB100 than in the other groups (p > 0.05). The relative weight of meat was not affected by the levels of SB (p = 0.428). However, the relative weight of meat trimmings was lower in SB75 and SB100 compared to SB25 (p = 0.020). The rib-eye area was lower in lambs fed 25%–100% sprouted barley (SB25–SB100) compared to the control diet (p = 0.001).

Table 5. Primary wholesale cuts and rack physical separation of lamb’s carcass fed sprouted barley.

Parameters	Sprouted barley levels (SB)
	Control	SB25	SB50	SB75	SB100	SEM^3	p-Value
Primary wholesale cuts (%)^1
Shoulder	29.3^b	29.3^b	29.9^b	31.6^a	32.1^a	0.87	0.041
Rack	9.6^a	8.8^ab	8.1^ab	7.5^c	7.1^c	0.39	0.001
Loin	13.7^a	12.9^a	11.7^b	11.3^b	10.9^c	0.64	0.022
Leg	29.4^b	32.7^ab	33.3^a	33.8^a	34.2^a	1.26	0.046
Foreshank and breast	18.0	16.2	17.0	15.7	15.8	1.44	0.764
Physical separation of rack (%)^2
Fat	7.84^a	7.83^a	6.83^a	7.11^a	5.17^b	0.41	0.009
Meat	65.8	63.6	67.7	67.8	65.0	1.82	0.428
Bone	21.7^b	21.9^b	20.6^b	21.1^b	26.8^a	1.51	0.041
Trimmings	4.6^ab	6.6^a	4.8^ab	3.9^b	3.0^b	0.70	0.020
Rib-eye area (cm²)	15.28^a	12.80^b	11.38^bc	11.63^bc	9.86^c	0.81	0.001

For superscripts (a–c), the difference in the mean values within the rows for each SB level is considered significant if p < 0.05.

The groups were fed diets containing 25%, 50%, 75% and 100% sprouted barley replacing the control diet of barley grain and alfalfa hay (SB25, SB50, SB75 and SB100, respectively).

¹ Cuts were computed based on hot carcass weight.

² Physical separation parameters were computed based on rack cut weight.

³ SEM = Standard error of means for diets effect.

3.5. Meat quality parameters

The physical properties of the carcass and meat of growing lambs fed different levels of SB are presented in Table 6. Meat pH values during 15 min and 24 h after slaughter (initial and ultimate) were not affected in lambs replaced by SB (p > 0.05). The initial temperature was lower in SB100 followed by SB75 (p < 0.0001), while the ultimate temperature was not affected compared to the control diet (p = 0.501). Meat color components such as lightness value (initial and ultimate) and yellowness value (ultimate) were higher in SB100 than in the control diet (p < 0.05). Other color components of meat and carcass and their derivatives (color change, yellow to redness ratio, chroma and hue angle) were not affected by SB (p > 0.05).

Table 6. Carcass and meat physical properties of growing lambs fed sprouted barley.

Parameters	Sprouted barley levels (SB)
	Control	SB25	SB50	SB75	SB100	SEM^3	p-Value
Initial pHi^1	6.27	6.03	6.10	6.23	6.17	0.08	0.255
Ultimate pHu^2	5.96	5.80	5.92	5.93	5.90	0.05	0.195
Initial Temp. (°C)	24.21^a	23.45^a	23.54^a	22.12^b	19.98^c	0.31	<0.0001
Ultimate Temp. (°C)	11.83	11.26	11.41	11.78	11.65	0.26	0.501
Initial meat color components
Lightness	35.32^b	35.98^b	36.16^b	36.54^b	39.42^a	0.74	0.006
Redness	12.22	12.00	12.40	12.52	12.36	0.46	0.943
Yellowness	5.21^b	5.33^b	5.42^b	5.44^b	6.76^a	0.34	0.020
Ultimate meat color components
Lightness	36.56^b	35.73^b	38.95^ab	37.57^ab	41.14^a	1.21	0.034
Redness	16.29	16.26	16.75	17.05	15.95	0.69	0.812
Yellowness	11.76	11.00	11.09	12.08	11.78	0.69	0.766
Meat color derivatives
Color change	3.35	3.09	3.54	3.44	3.03	0.30	0.713
Yellowness to redness ratio	0.72	0.68	0.66	0.71	0.73	0.02	0.383
Chroma	20.11	19.65	20.11	20.90	19.85	0.91	0.892
Hue angle	35.70	33.99	33.54	35.32	36.20	1.11	0.403
Ultimate carcass color components
Lightness	69.23	72.08	72.25	70.15	70.19	1.76	0.691
Redness	−0.74	−0.72	−2.73	−1.25	−1.83	0.72	0.275
Yellowness	12.12	11.85	10.59	10.66	12.69	1.01	0.518
Carcass color derivatives
Yellowness to redness ratio	−1.64	4.43	−5.21	−4.54	−7.66	3.87	0.253
Chroma	12.39	12.00	11.04	10.86	12.84	0.97	0.558
Hue angle	94.96	93.64	106.03	97.30	98.60	3.83	0.207

For superscripts (a–e), the difference in the mean values within the rows for each SB level is considered significant if p < 0.05.

The groups were fed diets containing 25%, 50%, 75% and 100% sprouted barley replacing the control diet of barley grain and alfalfa hay (SB25, SB50, SB75 and SB100, respectively).

¹ Initial = at 15 min after slaughter.

² Ultimate = at 24 h after slaughter.

³ SEM = Standard error of means for diets effect.

Meat quality characteristics of the growing lambs fed with SB are shown in Table 7. Lambs fed SB100 had a higher CL compared to SB50 and SB75 (p = 0.014). MFI was higher in lambs fed SB25 and SB75, while SF was lower in lambs fed SB100 compared to the other groups (p = 0.002). WHC was not affected by SB (p = 0.625). Texture profile parameters such as hardness (SB25, SB75 and SB100) and chewiness (SB75) increased compared to the other groups (p < 0.05). In contrast, other texture profile parameters (springiness, cohesiveness, and resilience) were not influenced by SB (p > 0.05).

Table 7. Meat quality characteristics of growing lambs fed sprouted barley.

Parameters^1	Sprouted barley levels (SB)
	Control	SB25	SB50	SB75	SB100	SEM^2	p-Value
CL%	34.2^abc	35.9^ab	26.3^c	27.9^bc	38.4^a	2.65	0.014
MFI	40.0^b	64.1^a	56.9^ab	74.6^a	44.2^b	6.11	0.002
WHC%	37.3	35.6	36.1	35.2	35.9	1.01	0.625
SF (N/cm^2)	24.8^a	23.7^a	22.7^a	21.9^ab	17.7^b	1.46	0.021
Texture profile analysis
Hardness (N)	16.6^b	21.5^a	14.3^b	25.8^a	24.3^a	3.11	0.050
Springiness ratio	0.59	0.56	0.60	0.61	0.62	0.02	0.222
Cohesiveness ratio	0.49	0.47	0.50	0.52	0.53	0.02	0.195
Chewiness ratio	4.49^b	5.11^ab	4.30^b	8.86^a	7.72^a	1.05	0.015
Resilience ratio	0.21	0.20	0.20	0.22	0.23	0.01	0.210

For superscripts (a–e), the difference in the mean values within the rows for each SB level is considered significant if p < 0.05.

The groups were fed diets containing 25%, 50%, 75% and 100% sprouted barley replacing the control diet of barley grain and alfalfa hay (SB25, SB50, SB75 and SB100, respectively).

¹ CL = cooking loss; MFI = myofibril fragmentation index; WHC = water-holding capacity; SF = shear force.

² SEM = Standard error of means for diets effect.

3.6. Meat fatty acids determination

The profile of fatty acid methyl esters in meat of growing lambs fed SB is shown in Table 8. The palmitic acid (C16:0) and saturated fatty acid (SFA) content decreased in lambs fed SB25 and SB50 compared with the control diet (p < 0.05). In addition, tetradecenoic acid (C14:1 n–5) in SB50, linolenic acid (C18:3 n–3) in SB100 were lower compared with the control diet (p < 0.05). In contrast, myristic acid (C14:0) in SB100 and oleic acid (C18:1 n–9) and total monounsaturated fatty acids (MUFA) were increased in SB25 and SB50 compared with the control diet (p < 0.05). Other fatty acid profiles of the meat were not affected by SB (p > 0.05).

Table 8. Meat fatty acid methyl esters profile (%) of growing lambs fed sprouted barley.

Parameters^1	Sprouted barley levels (SB)
	Control	SB25	SB50	SB75	SB100	SEM^2	p-Value
Saturated fatty acids (SFA)
C10:0	0.29	0.20	0.21	0.22	0.24	0.03	0.503
C12:0	0.52	0.48	0.73	0.57	0.82	0.15	0.497
C14:0	4.61^b	3.86^b	4.17^b	4.46^b	6.07^a	0.36	0.002
C15:0	0.88	0.76	0.84	0.76	0.92	0.09	0.655
C16:0	26.05^a	23.27^c	24.15^bc	25.19^ab	26.25^a	0.60	0.008
C17:0	2.89	2.27	2.93	3.08	2.67	0.26	0.253
C18:0	15.11	15.25	14.88	15.39	15.84	0.84	0.945
ΣSFA	50.35^ab	46.11^c	47.92^bc	49.69^ab	52.38^a	1.13	0.007
Monounsaturated fatty acids (MUFA)
C14:1 n–7	0.32	0.21	0.27	0.37	0.33	0.07	0.622
C14:1 n–5	0.23^ab	0.21^ab	0.17^b	0.25^ab	0.34^a	0.03	0.033
C16:1 n–7	2.64	2.67	2.66	2.72	2.83	0.11	0.804
C16:1 n–5	0.26	0.23	0.24	0.28	0.38	0.03	0.371
C18:1 n–7	2.45	2.52	1.92	2.45	2.65	0.20	0.160
C18:1 n–5	0.89	0.90	0.72	0.70	0.67	0.11	0.513
C18:1 n–9	36.10^b	39.14^a	38.86^a	36.03^b	34.98^b	0.79	0.002
C20:1 n–9	0.24	0.42	0.30	0.24	–	0.11	0.609
ΣMUFA	43.04^bc	46.10^a	45.12^ab	42.80^bc	41.70^c	0.89	0.011
Polyunsaturated fatty acids (PUFA)
C16:3 n–4	0.98	1.48	1.10	1.01	0.81	0.25	0.434
C18:2 n–6	3.63	4.16	3.90	4.01	3.19	0.36	0.417
C18:2 n–7	0.29	0.32	0.26	0.33	0.35	0.04	0.596
C18:3 n–3	0.33^a	0.30^a	0.27^ab	0.28^ab	0.19^b	0.03	0.050
C18:4 n–3	0.26	0.26	0.39	0.29	0.28	0.04	0.174
C20:4 n–6	0.63	0.62	0.64	0.59	0.70	0.12	0.976
ΣPUFA	6.08	5.77	6.54	6.46	5.28	0.70	0.705
Σ n–6	4.26	3.39	4.55	4.60	3.89	0.57	0.560
Σ n–3	0.59	0.57	0.67	0.57	0.48	0.05	0.179
Σ n–6/Σ n–3	7.26	5.80	7.28	8.01	8.79	1.03	0.388
ΣPUFA/ΣSFA	0.12	0.13	0.13	0.13	0.10	0.01	0.668

For superscripts (a–e), the difference in the mean values within the rows for each SB level is considered significant if p < 0.05.

The groups were fed diets containing 25%, 50%, 75% and 100% sprouted barley replacing the control diet of barley grain and alfalfa hay (SB25, SB50, SB75 and SB100, respectively).

¹ Data are expressed as the percentage of total fatty acids identified.

² SEM = Standard error of means for diets effect.

4. Discussion

The current results showed that the addition of 25%–75% SB (SB25–SB75) had no negative effect on BWG, while SB100 resulted in a lower BWG than the control diet. The lower BWG in lambs receiving SB100 could be attributed to lower DMI. The DMI is an important indicator, when it decreases, the lambs do not meet the nutrient requirements to achieve the ideal BWG compared to the control diet. This is consistent with the results of nutrient analysis of SB (Table 1), were DM was lower in SB100 (20.1%) than in the control diet (95.5%). Thus, the lambs do not have the opportunity to increase DMI, which may affect growth, as noted in a previous study (Morales et al., 2009). These findings are consistent with the research conducted previously (Muhammad et al., 2013), which suggested that lambs fed higher levels of SB may have a negative impact on growth performance indices. It has been found that lambs fed SB100 consumed less DM than traditional feed, which may lead to a decrease in growth performance (Farghaly et al., 2019). In contrast, a previous study showed that lambs fed 62% sprouted barley for 90 days had a positive effect on body weight gain and feed intake compared to total mixed ration feed (Ata, 2016). In addition, feeding lambs a concentrated mixture with SB (50:50) increased DMI and BWG (Devendar et al., 2020). These results suggest that SB can be replaced as part of the traditional feed that meets the nutritional requirements of lambs in terms of quantity and quality to maintain growth performance. Hydroponic cultivation of barley has been observed to result in alterations in nutrient composition, leading to an increase in CP and CF content. This change can be attributed to the activity of hydrolytic enzymes compared to barley seeds (Al-Saadi & Al-Zubiadi, 2016; Ikram et al., 2021). The results of the current study, which showed that CPI and CFI decreased compared to the control diet. However, lower CPI and CFI with an increase in SB may be due to reduced DMI. In addition, the use of SB in feeding lambs could result in better outcomes when DMI was raised to improve performance. In lambs fed SB, all nutrient conversion ratios (DM, CP, and CF) were unaffected compared with the control diet. These results suggest that lambs fed SB had the same effect on nutrient utilization as lambs fed barley grain and alfalfa hay (the control diet). Study reported that goats fed 20% and 40% SB had higher BWG, DMI and CPI with improved nutrient utilization compared to the basal diet (alfalfa hay and wheat straw) (Arif et al., 2023).

Dressing percentage and carcass components are important criteria for evaluating carcass characteristics and slaughter value of lambs (Shewita & Taha, 2018). In contrast, the decrease in lambs fed SB100 could be due to the lower live weight of the lambs before slaughter. Lambs fed SB100 had higher relative chill shrink compared to the control diet. This could be due to increased moisture loss after chilling due to drip loss and evaporation in the absence of fat on the carcass, especially the outer fat in SB100. Carcass fat acts as an insulator and prevents the loss of liquids from the carcass (Castro et al., 2017). The relative weight of genitals increased, while head and heart decreased in lambs fed SB25 to SB75 and tail decreased in lambs fed SB50 and SB100 compared to the control diet. Study reported that replacement of SB had no effect on carcass characteristics and body components of growing lambs (Devendar et al., 2020). Body wall fat was lower in SB100 compared to the control diet. This is consistent with other studies which have shown that lambs on high forage tend to deposit less subcutaneous fats (Papi et al., 2011). In contrast, other fat depot measurements such as back fat, pericardial fat, KKCF, omental fat, and mesenteric fat was not affected by SB. The results of the current study showed that the relative weight of primary wholesale cuts, including shoulder (SB75–SB100) and leg (SB25–SB100), increased compared with the control diet, while that of rack (SB50–SB100) and loin (SB75–SB100) decreased. This is attributed to the protein, carbohydrate, and uptake of minerals present in the introduced diet of SB. On the other hand, the relative weight of bone in SB100 and trimmings in SB25 increased compared to the control diet. Rib-eye area decreased in SB50 to SB100 compared to the control diet. Nutrients change could develop a mechanism in the lambs, apart from environmental influences and the same testing parameters, to adapt in a certain way so that the lambs develop differently.

In this study, we evaluated carcass and meat physical property indicators and meat quality traits, including pH, temperature, color components, CL, MFI, WHC, SF, and texture profile analysis. These parameters can significantly affect the quality of fresh meat at the point of sale (Kim et al., 2020). In addition, these indicators can determine consumer purchasing power (Maltin et al., 2003). We found that feeding lambs supplementary barley (SB) had no effect on carcass and meat physical characteristics, including pH, temperature, and color components, except for the lightness value of initial and ultimate meat color. The lightness value of the initial and ultimate meat color was higher in lambs fed SB100. The yellowness value of the initial meat color was also higher in lambs fed SB100. In addition, feeding lambs with SB75 and SB100 resulted in a decrease in initial meat temperature may be due to lower slaughter live weight and the thickness of the external fat, especially lambs fed SB100, which leads to rapid loss of body heat within 15 min after slaughter.

The color change in the meat of lambs fed SB100 may be attributed to green carotenoids (Carrasco et al., 2009). Carotenoids are pigments that give plants and lambs their characteristic colors. Green carotenoids are found in barley, and they can be transferred to the meat of lambs that eat barley. The higher lightness value of meat from lambs fed SB100 may be due to the increased fat content of the meat. Fat reflects light, so meat with a higher fat content will appear lighter in color. The higher yellowness value of meat from lambs fed SB100 may also be due to the increased fat content of the meat. Carotenoids are fat-soluble, so they are more concentrated in fatty tissues. This can give the meat a yellow or orange color (Carrasco et al., 2009). Overall, our findings suggest that feeding lambs supplementary barley does not have a significant effect on the physical characteristics of the carcass or meat. However, it may slightly affect the color of the meat.

A lower CL value indicates less water loss during cooking, which can lead to juicier meat. This is in line with the proven relationship between CL and juiciness (Hussein et al., 2020). In this study, lambs fed SB50 and SB75 compared to SB100 might enhance water retention in the meat due to water lost during cooking. This could be due to a better balance of fat deposition in back fat and body wall fat, but the exact mechanism needs further investigation. In addition, lambs fed SB50 and SB75 diets might provide a more balanced nutrient and fat intake compared to SB100. This balanced intake could contribute to less moisture loss during cooking (Karaca et al., 2016). Moreover, WHC is one of the most important functional markers for measuring the ability of the meat to retain water (Devatkal et al., 2019; Davoodi & Ehsani, 2020). Our results showed that the WHC value did not differ between the different SB. The MFI was increased in lambs fed SB25 and SB75 compared to the control diet. This suggests that the SB may have made the meat firmer. However, the reason behind increased firmness with SB25 and SB75 is unclear and requires further investigation. The SF was lower in lambs fed SB100 compared to lambs fed the control diet. This suggests that the SB100 may have made the meat less tough due to its moisture content, which reached 79.9% according to a chemical analysis of the nutrients in the SB. The texture profile parameters of hardness and chewiness were increased in lambs fed SB25, SB75, and SB100 compared to lambs fed no SB. This suggests that the SB may have made the meat harder and chewier. The hardness and chewiness of meat is influenced by many factors, especially the proteins in the meat, the amount of water in the muscles and the cooking process. During cooking, the strength of the internal bonds can decrease due to the decomposition of the proteins, which can lead to a brittle structure and thus increase chewiness (Pematilleke et al., 2022).

The fatty acid profile of lamb’s meat is crucial for meat quality. Customers are increasingly interested in the nutritional value of meat, so our current study we focused on the analysis of meat fatty acids (Osman et al., 2023). In addition, determining the fatty acid profile of meat has a significant impact on lambs meat quality and human health, as the fat in meat is not trimmable before consumption (Rahimi et al., 2011; Aghwan et al., 2014). The changes in the fatty acid profile may be attributed to the following: (i) the levels of substitution of common forages used (the control diet; barley grain and alfalfa) with SB, (ii) hydrolytic enzymes in SB potentially improve nutrient content, influencing meat fat deposition, and (iii) the modification of the rumen ecosystem by SB, which can affect the production of fatty acids.

The results showed that the levels of palmitic acid (C16:0), saturated fatty acids (SFAs), and the omega–6 to omega–3 (n–6/n–3) ratio were lower in lambs fed SB25 compared to those fed the control diet. The enzymes of SB could increase the nutrient content in feed, influence fat deposition in meat and possibly reduce palmitic acid and SFAs (Raeisi et al., 2018). Palmitic acid is a saturated fatty acid that has been linked to cardiovascular disease and increased cholesterol levels (Howes et al., 2015). Therefore, the decrease in palmitic acid, SFAs, and n–6/n–3 in lambs fed 25% SB is desirable for human health. The levels of myristic acid (C14:0) and oleic acid (C18:1 n–9), as well as the monounsaturated fatty acids (MUFAs), were higher in lambs fed SB25 and SB50 compared to those fed the control diet. This is because SB is a good source of MUFAs, which are considered to be beneficial for human health. MUFAs can help to lower cholesterol levels and reduce the risk of heart disease. The levels of other fatty acids were not affected by the level of SB intake. This suggests that SB has a selective effect on the fatty acid profile of lamb’s meat. Sprouted barley (SB), parti­cularly at the 25% inclusion, appears to improve the lamb meat’s fatty acid profile from a human health perspective, potentially lowering saturated fat and increasing beneficial MUFAs. However, further research is needed to fully understand the underlying mechanisms.

6. Conclusion

In conclusion, the results showed that the partial replacement of traditional feed with SB had beneficial effects on lamb through maintaining performance and certain aspects of meat quality. Particularly, a 25% inclusion level of SB resulted in the lowest saturated fatty acids and the highest monounsaturated fatty acids in the meat. Overall, the study suggests that SB could be a valuable partial replacement for traditional feeds, with potential benefits for the performance and meat quality of growing lambs. However, further research is needed to verify the optimal use of SB as a feeding system for growing lambs.

Authors’ contributions

Methodology, formal analysis, data curation and writing-original draft were performed by S. Al-Ghamdi, H. Al-Baadani, I. Alhidary, A. Alharthi. Conceptualization, and project administration by I. Alhidary. Investigation, review and editing by S. Al-Ghamdi, A. Alharthi, W. Soufan, G. Suliman, M. Abdelrahman. All authors have read and agreed to the published version of the manuscript.

Institutional review board statement

All procedures of the present study, including lambs husbandry, slaughter, and sampling, were approved according to the guidelines of the Scientific Ethics Committee of King Saud University, Saudi Arabia (KSU–SE-22–01).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, [W.S], upon reasonable request.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

The authors thank King Saud University, Riyadh, Saudi Arabia, for funding this work through the Research Project Group (RSPD2024R833).

Notes on contributors

Saleh Al-Ghamdi

Saleh Al-Ghamdi Assistant Professor at the Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University. My research interest is in modern methods to improve meat quality.

Hani H. Al-Baadani

Hani H. Al-Baadani Assistant Professor at King Saud University at the Department of Animal Production. My research interests include the effects of nutrition and feed additives on animal health and their impact on production performance.

Abdulrahman S. Alharthi

Abdulrahman S. Alharthi Assistant Professor at King Saud University at the Department of Animal Production. My research interests include the effects of nutrition on gene expression, health and performance.

Walid Soufan

Walid Soufan Associate Professor at Plant Production Department, Collage of Food and Agricultural Sciences, King Saud University. His research interests include crop production and physiology, modern trends in forage crop production and hydroponic crop production.

Gamaleldin M. Suliman

Gamaleldin M. Suliman Professor at King Saud University at the Department of Animal Production. My research interests include the effects of nutrition on meat production and quality.

Mutassim M. Abdelrahman

Mutassim M. Abdelrahman Professor at King Saud University at the Department of Animal Production. My research interests include the effects of nutrition on the physiology of ruminants.

Ibrahim A. Alhidary

Ibrahim A. Alhidary Professor at King Saud University at the Department of Animal Production. My research interests include the effects of nutrition on the physiology of the digestive system in ruminants.