Enhancing lactational performance of Holstein dairy cows under commercial production: malic acid as an option

l-Malic Acid Facilitates Stem Cell-Driven Intestinal Epithelial Renewal through the Amplification of β-Catenin Signaling by Targeting Frizzled7 in Chicks

l-Malic acid (l-MA) contributes to energy metabolism and nutrient digestion, which is an alternative to antibiotics for livestock; however, it is not clear whether l-MA can replace antibiotics to promote intestinal development in chicks. To investigate the effects of l-MA on intestinal stem cells (ISCs) driving epithelial renewal, we employed in vivo chick feeding experiments, chick intestinal organoid (IO) models, and in vitro chick intestinal epithelial cell models. The results showed that the feed conversion rate and diarrhea scores were decreased with improved jejunal morphology and barrier function in the 0.5% l-MA group. l-MA promoted the proliferation and differentiation of ISCs, inhibited the cell apoptosis, increased the IO formation efficiency, surface area, budding efficiency, and number of buds, suggesting that l-MA promoted the expansion of ISCs. Furthermore, l-MA treatment dramatically upregulated the Wnt/β-catenin signaling pathway in the jejunum. Importantly, Wnt transmembrane receptor Frizzled7 (FZD7) mRNA abundance was increased in response to dietary 0.5% l-MA. In addition, molecular docking analysis using Autodock software and isothermal titration calorimetry revealed that l-MA binds to Lys91 of FZD7 with high affinity, indicating a spontaneous interaction. The chick intestinal epithelial cells treated with 10 μM l-MA significantly increased cell viability, and the Wnt/β-catenin signaling pathway was activated, but l-MA failed to upregulate the Wnt/β-catenin signaling when treated with the FZD7-specific inhibitor Fz7-21 in chick intestinal epithelial cells, indicating that FZD7 is indispensable for l-MA activation of the Wnt/β-catenin signaling. Collectively, l-MA stimulated β-catenin signaling by targeting transmembrane receptor FZD7, which promoted ISC expansion and inhibited cell apoptosis to accelerate intestinal epithelial renewal in chicks.

Bio-Fermented Malic Acid Facilitates the Production of High-Quality Chicken via Enhancing Muscle Antioxidant Capacity of Broilers

Malic acid, an intermediate of the tricarboxylic acid (TCA) cycle, is a promising acidifier with strong antioxidant capacity. This study aimed to evaluate the effects of bio-fermented malic acid (BFMA) on promoting the body health, performance and meat quality of broilers. A total of 288 one-day-old Arbor Acres male broiler chicks were randomly divided into four treatments with six replicates in each. Every replicate had 12 chicks. Four experimental diets contained 0, 4, 8, and 12 g/kg BFMA, respectively. During the 42-day trial, mortality was recorded daily, feed intake and body weight of each replicate being recorded every week. Blood samples were collected on days 21 and 42 for chemical analysis. After slaughter at the age of 42 days, the carcass traits and meat quality of the broilers were measured, breast muscle samples were collected for the determination of antioxidant capacity, and cecal digesta were pretreated for microbiota analysis. Dietary BFMA significantly increased feed intake and daily gain, and decreased feed conversion ratio and death and culling ratio of the broilers at the earlier stage. The water-holding capacity of breast muscle indicated by the indexes of dripping loss and cooking loss was significantly increased by BFMA, especially at the addition level of 8 g/kg. Dietary BFMA significantly decreased the activity of superoxide dismutase and contents of immunoglobulin A and glutathione, and increased contents of immunoglobulin G and M in serum of the broilers. The contents of glutathione, inosinic acid, and total antioxidant capacity and the activities of glutathione-Px and superoxide dismutase were significantly increased by dietary BFMA, with the level of 8 g/kg best. The diversity of cecal microbiota of broilers was obviously altered by BFMA. In conclusion, as one of several acidifiers, addition of BFMA in diets could improve the performance and body health of broilers, probably by reinforcing immunity and perfecting cecal microbiota structure. As one of the intermediates of the TCA cycle, BFMA increases the water-holding capacity of breast muscle of broilers, probably through reducing lactate accumulates and enhancing antioxidant capacity.

Addition of Organic Acids and Lactobacillus acidophilus to the Leguminous Forage Chamaecrista rotundifolia Improved the Quality and Decreased Harmful Bacteria of the Silage

This study aimed to investigate the effects of citric acid, malic acid, and Lactobacillus acidophilus (L) on fermentation parameters and the microbial community of leguminous Chamaecrista rotundifolia silage. Fresh C. rotundifolia was treated without any additive (CK), or with L (106 CFU/g fresh weight), different levels (0.1, 0.3, 0.5, and 1% fresh weight) of organic acid (malic or citric acid), and the combinations of L and the different levels of organic acids for 30, 45, and 60 days of ensiling. The effects of malic acid and citric acid were similar during the ensiling process. Treatment with either citric or malic acid and also when combined with L inhibited crude protein degradation, lowered pH and ammonia nitrogen, and increased lactic acid concentration and dry matter content (p < 0.05). The neutral detergent fiber and acid detergent fiber increased initially and then decreased with fermentation time in all treatments (p < 0.05). Increasing the level of organic acid positively affected the chemical composition of C. rotundifolia silage. In addition, the addition of 1% organic acid increased the relative abundance of Lactobacillus, while the relative abundances of Clostridium and Enterobacter decreased at 60 days (p < 0.05). Moreover, both organic acids and combined additives increased (p < 0.05) the relative abundance of Cyanobacteria at 60 days of fermentation. We concluded that adding malic acid, citric acid, and L combined with an organic acid could improve the quality of C. rotundifolia silage and increase the relative abundance of beneficial bacteria. The addition of organic acid at a level of 1% was the most effective.

Utilization of Waste Date Palm Leaves Biomass Ensiled with Malic or Lactic Acids in Diets of Farafra Ewes under Tropical Conditions

The aim of the current study was to evaluate the ensiling of date palm leaves (DPL) with organic acids (lactic or malic acid) for 45 day as a feed for lactating ewes under desert conditions. Two weeks before expected parturition, 50 multiparous lactating Farafra ewes (mean ± SD: 2 ± 0.3 parity, 34 ± 1.9 kg bodyweight, 25 ± 2.4 months of age, and 555 ± 13.0 g/day of previous milk production) were equally divided into five treatments in a completely randomized design for 90 day. The ewes in the control treatment were offered a diet composed of a concentrate feed mixture and DPL at 60:40 on a dry matter (DM) basis ensiled without additive. In the other treatments, DPL (ensiled without organic acids) in the control treatment was replaced with DPL ensiled with lactic or malic acid (at 5 g/kg DM) at 50 or 100% levels. Organic acids linearly and quadratically increased (p < 0.01) DPL and total intakes and digestibilities of DM, organic matter, crude protein, and nonstructural carbohydrates without affecting fiber digestibility. Malic and lactic acid treatment also increased the concentrations of ruminal total volatile fatty acids, acetate, propionate, and ammonia-N. Additionally, malic and lactic acid-treated DPL increased serum glucose concentration and total antioxidant capacity. Without affecting daily actual milk production, treatments increased (p < 0.001) the daily production of energy-corrected milk (ECM), fat-corrected milk (FCM), milk energy output, milk contents of fats, and feed efficiency. Organic acid-treated DPL increased (p < 0.05) the proportions of total polyunsaturated fatty acids and total conjugated linoleic acids and the unsaturated to saturated fatty acid ratio in milk. It is concluded that feeding DPL ensiled with malic or lactic acid at 20 or 40% of total diet DM increased daily ECM and FCM production, nutrient utilization efficiency, and milk quality. No differences were observed between lactic and malic acid treatment of DPL during ensiling; therefore, both of them are recommended to treat DPL for silage preparation.

The Effect of Sustainable Feeding Systems, Combining Total Mixed Rations and Pasture, on Milk Fatty Acid Composition and Antioxidant Capacity in Jersey Dairy Cows

This study was carried out to assess the effect of using pasture combined with total mixed ration (TMR) on milk production and composition, fatty acid (FA) profiles, fat-soluble antioxidant content, and total milk antioxidant capacity (TAC). In addition, the effect of milk pasteurization and storage at 2 °C for 4 days, lipophilic antioxidants and TAC were assessed. Two homogeneous groups of Jersey cows (n = 8) were constituted, which were randomly assigned to one of the two treatments: TMR (without access to pasture), or partial mixed diet (pTMR: grazing 8 h/day + TMR indoors). To establish FA profiles and lipophilic antioxidants’ changes in milk during the grazing period, in case of the pTMR group the experimental period was spilt in three grazing periods: P1 (May), P2 (June), and P3 (June/July). Milk yielded from cows having limited access on pasture (pTMR diet) showed an improved FA profile, with higher concentrations of FAs considered benefic for human health (vaccenic acid (VA), conjugated linoleic acid (CLA), omega-3 FA (n-3 FA)) (p < 0.01) and a lower concentration of FAs with hypercholesterolemiant potential (C12:0, C14:0, and C16:0) (p < 0.05), compared to that of the TMR diet. This change in FA profile was correlated with improved sanogenous lipid indices of milk fat (n-6/n-3 FA atherogenic index and thrombogenic index). Milk yielded during the P1 grazing period had higher concentrations of VA, CLA, and n-3 FA (p < 0.05) and lower concentrations of C14:0 and C16:0 (p < 0.01); it exhibited the best values for the main sanogenous fat lipid indices of fat. Moreover, pTMR milk showed a higher α-tocopherol, retinol, and β-carotene content (p < 0.05), positively correlated with TAC values in milk (P1 ˃ P2 ˃ P3). By comparison, cows fed using the TMR diet yielded a higher quantity of milk (p < 0.05), but a lower fat and protein content (p < 0.01), and also a higher saturated FAs and n-6 FA content (p < 0.05) together with a lower concentration of lipophilic antioxidants in milk. Thermal treatment showed no effect on α-tocopherol and retinol content in milk, but their concentrations decreased during the storage, at the same time a TAC decrease. The results of this study prove the positive effect of using pasture combined with TMR on FA profiles, milk antioxidant content, and antioxidant capacity, with beneficial effects on nutrition and health in humans.

Valorization of a Pyrolytic Aqueous Condensate and Its Main Components for L-Malic Acid Production with Aspergillus oryzae DSM 1863

Pyrolytic aqueous condensate (PAC) might serve as a cost-effective substrate for microbial malic acid production, as it is an unused side stream of the fast pyrolysis of lignocellulosic biomass that contains acetol and acetate as potential carbon sources. In the present study, shake flask cultures were performed to evaluate the suitability of acetol and its combination with acetate as substrates for growth and L-malate production with the filamentous fungus Aspergillus oryzae. Acetol concentrations of up to 40 g/L were shown to be utilized for fungal growth. In combination with acetate, co-metabolization of both substrates for biomass and malate formation was observed, although the maximum tolerated acetol concentration decreased to 20 g/L. Furthermore, malate production on PAC detoxified by a combination of rotary evaporation, overliming and activated carbon treatment was studied. In shake flasks, cultivation using 100% PAC resulted in the production of 3.37 ± 0.61 g/L malate, which was considerably improved by pH adjustment up to 9.77 ± 0.55 g/L. A successful scale-up to 0.5-L bioreactors was conducted, achieving comparable yields and productivities to the shake flask cultures. Accordingly, fungal malate production using PAC was successfully demonstrated, paving the way for a bio-based production of the acid.

Influence of Replacement Levels of Orange Waste Silage on Intake, Nutrient Digestion, Ruminal Fermentation and Milk Yield in Barki Goats

Exploring new alternative sources of feedstuffs can contribute to animal production sustainability in some Mediterranean regions in order to overcome the rising food demand. The influence of dietary replacement of wheat straw (WS) with orange waste silage (OWS) on nutrient intakes, apparent digestibility, ruminal fermentation and blood biochemical constituents and milk production of dairy goats were evaluated. Forty pregnant goats (46.30±1.6 kg BW) were housed in individual pens in a completely randomized design and fed (ad libitum) a TMR for 75 days period. Goats were assigned to four experimental diets with the forage amounts consisting of either WS as a control diet (1000 g WS/kg DM in the TMR), a 50:50 mixture of both WS and OWS (500 g WS and 500 g OWS/kg DM in the TMR), an orange waste silage (1000 g OWS/kg DM in the TMR) or corn silage as a positive control (1000 g CS/kg DM in the TMR). The DMI increased linearly (P<0.01), while fiber fractions intake decreased linearly (P<0.01) with increasing of OWS in the diet. Ruminal pH was increased quadratically (P<0.01), whereas NH3-N concentration and total protozoa abundance decreased quadratically (P<0.01) with increasing OWS in the diet. Ruminal acetate content was increased linearly (P = 0.012) by diet; whereas linear effects were observed on propionate and butyrate proportions (P<0.01) as OWS amount increased. Blood urea nitrogen (BUN), non-esterified free fatty acids (NEFA) and β-hydroxybutyrate (BHBA) levels decreased linearly (P<0.01) with ascending amounts of OWS. Serum glucose, BUN, NEFA and BHBA levels were lower (P<0.01) for goats fed the OWS diet than those fed the CS diet. Milk yield and milk nitrogen efficiency were linearly increased (P<0.01), whereas quadratic effects (P = 0.049) were observed on milk urea nitrogen content with increasing dietary OWS. In conclusion, the replacement of WS with OWS enhanced rumen fermentation and milk yield of late pregnant and early lactation Barki goats.

Potential of graded doses of neem (Azadirachta indica) seed oil on ruminal fermentation characteristics, degradability, and methane formation in vitro

Neem (Azadirachta indica) belongs to Meliaceae family, represented mainly by trees, and widely cultivated and adapted in many tropical regions. The objective of this study was to evaluate the effect of increasing doses of neem seed oil (NSO) on ruminal methane (CH4) formation, diet degradability, and fermentation characteristics 24 h of in vitro incubation. Treatments were randomly designed to four doses of NSO supplemented to the basal diet (0, 20, 40, or 60 ml/kg DM). Increasing NSO dose resulted in a quadratic decrease (P < 0.05) in net gas (expressed as ml/g DM and ml/g TDOM) and CH4 (expressed as ml/g TDNDF) production, while CH4 (expressed as ml/g TDOM), acetate and propionate proportions decreased linearly confirming a dose-related effect. A quadratic increase in TDOM and linear increase (P = 0.023) in DNDF, NH3-N concentrations, and total protozoal counts were observed. However, a linear increase (P = 0.009) was found in the ruminal butyrate proportion and partitioning factor as dietary NSO supplementation increased. In conclusion, dietary NSO supplementation mediated some desirable fermentation patterns, reducing ruminal NH3-N concentration and CH4 production with some adverse effects on fiber degradability. However, practical research under long-term conditions is required for further investigation.

Effect of supplementing Leucaena leucocephala leaves alone or in conjunction with malic acid on nutrient utilization, performance traits, and enteric methane emission in crossbred calves under tropical conditions

Dietary strategies aiming at minimizing enteric methane (CH₄) emission in ruminants are of practical interest from nutritional, economical, and environmental point of view. The present study evaluated the effects of supplementing Leucaena leucocephala leaves either alone or in conjunction with malic acid on nutrient utilization, growth performance, and enteric CH₄ emission in crossbred cattle fed wheat straw and concentrate-based diet under tropical conditions. Eighteen crossbred (Karan-Fries) calves were randomly allocated into 3 groups: G-I (control)-fed wheat (Triticum aestivum) straw and concentrate mixture in the ratio 50:50; G-II-fed wheat straw, concentrate mixture, and Leucaena leucocephala leaves in the ratio 45:45:10; and (3) G-III-fed similar diet like G-II with an additional supplementation of 1% malic acid on dry matter intake basis. Experimental feeding spanning 90 days included a 7-day metabolism trial and CH₄ quantification study by sulfur hexafluoride tracer technique. Results revealed no significant effect of dietary treatments on dry matter intake (DMI) and digestibility of nutrients, except neutral detergent fiber (NDF) digestibility which was 5.5% higher (P < 0.05) in G-III as compared to control. Further, nitrogen (N) metabolism, rumen microbial protein synthesis, and growth performance remained similar among the treatments. No significant effect was also observed for enteric CH₄ emission (expressed as g/day and g/kg DMI) in calves supplemented with Leucaena leucocephala leaves and malic acid. Therefore, the present findings depict modest improvement in fiber digestibility with no encouraging effect in mitigating enteric CH₄ in growing cattle calves by supplementing Leucaena leucocephala leaves alone or with malic acid within the selected levels.

Dietary strategies to enrich milk with healthy fatty acids – a review

Feed is the main factor impacting the composition and quality of milk of dairy animals. Therefore, the present review explores the effects of feed and nutrition on milk fat content and levels of healthy fatty acids (FA) in milk consumed by humans. Milk and dairy products are two main sources of healthy and unhealthy FA in human nutrition. The concentrations of FA in milk depend mainly on diets; therefore, milk FA concentrations and ratios can be greatly altered by some feeding strategies. Dietary supplementation of the diets of dairy livestock with vegetable seeds or oils, microalgae and phytogenic feed additives, and feeding of some grasses can enhance the contents of healthy FA, including n-3 FA, α-linolenic acid, conjugated linoleic acid (CLA) and, generally, unsaturated FA in milk and dairy products. Enrichment of milk with healthy FA may make milk a source of anticarcenogens (CLA and polyphenols) for human health. This review, therefore, focusses on the current research findings on enrichment of milk with healthy FA and summarizes some effective supplementation strategies to alter milk FA profile.

Chlorella vulgaris Microalgae and Copper Mixture Supplementation Enhanced the Nutrient Digestibility and Milk Attributes in Lactating Boer Goats

Thirty-two lactating Boer goats (35.2 ± 1.4 kg body weight) were grouped into control and three treatment groups in completely randomised design. In treatment groups, supplementation was done as a mixture of 5 g Chlorella vulgaris + 4.5 mg of supplemental Cu/kg diet from CuSO4 (Alg5 treatment), 10 g C. vulgaris + 9 mg of supplemental Cu/kg diet (Alg10 treatment), or a mixture of 15 g C. vulgaris + 13.5 mg of supplemental Cu/kg diet (Alg15 treatment). Treatments did not affect feed intake; however, Alg10 treatment increased (P<0.001) nutrient digestibility. Treatments did not affect ruminal pH, ammonia-N, butyrate; however, the Alg10 treatment increased (P<0.01) ruminal total volatile fatty acids, propionate and acetate concentrations. Without affecting other blood measurements, the Alg10 treatment quadratically increased (P<0.001) serum glucose and Cu. The Alg10 treatments increased (P<0.001) daily milk production and the concentration of fat, and enhanced milk (feed) efficiency. The Alg10 treatment decreased (P<0.05) milk saturated fatty acids and the atherogenic index, and increased the proportions of total conjugated linoleic acids, C18:1n9t, odd fatty acids and total unsaturated fatty acids compared with the control treatment. Present study concluded that inclusion of a mixture of 10 g C. vulgaris + 9 mg Cu/kg diet in the diet of lactating Boer goats enhanced nutrient digestibility, ruminal fermentation, milk production, feed efficiency as well as milk nutritive value. Increasing the dose of the mixture to 15 g C. vulgaris + 13.5 mg Cu/kg diet is not recommended in the diet of lactating Boer goats.

Enrichment of common carp (Cyprinus carpio) diet with Malic acid: Effects on skin mucosal immunity, antioxidant defecne and growth performance

The present study investigated possible effects of dietary malic acid on the expression of immunity, antioxidant and growth related genes expression as well as skin mucus immune parameters in common carp. Common carp (Cyprinus carpio) fingerlings were fed diets supplemented with different levels (0 [control], 0.5%, 1%, 2%) of malic acid (MA) for 60 days. The results revealed highest expression levels of immune-related genes (tnf-alpha, il1b, il8 and lyz) in skin of common carp fed 2% MA (P < 0.05). Regarding 1% MA treatment comparison with control group, significant difference was noticed just in case of lyz (P < 0.05). Evaluation of growth related genes expression revealed no significant difference between treatments (P > 0.05). The study of antioxidant related genes (gsta and gpx) in common carp skin fed with MA, showed significant difference between treated groups and control (P < 0.05). Carps fed with 2% MA had highest alkaline phosphatase activity in skin mucus compared other treated groups and control (P < 0.05). There were no significant difference between 0.5% and 1% and control (P > 0.05). The study of total protein and total immunoglobulin (Ig) in common carp skin musus revealed no alteration following MA treatment (P > 0.05). The present data demonstrated that feeding with MA altered immune and antioxidant genes expression in skin mucus of common carp.

The Mode of Grass Supply to Dairy Cows Impacts on Fatty Acid and Antioxidant Profile of Milk

The optimization of milk production includes a rational use of forages, respect for the environment and offers the best quality to consumers. Milk production based on grass and forages produces healthier milk and it is widely spread throughout the Atlantic arc to maximize milk yield per hectare. However, the mode of offering the grass can have a major influence on milk composition. The aim of this study was to evaluate the effect of grass supply mode (grazing, zero-grazing or ensiling) on dairy cows’ performance, with particular reference to fatty acids and fat-soluble antioxidants concentration. A three by three Latin square experiment was performed with 18 dairy cows. Experimental treatments consisted of exclusive feeding with grass silage and zero-grazing, both offered ad libitum indoors, or grazing for 24 h. The results showed that grazing cows had a higher dry matter intake and greater milk yield than cows feeding on grass silage and zero-grazing, as well as higher concentrations of protein, lactose, nonfat-solids and urea in milk than housed cows. Milk fat from grazing cows had a higher proportion of unsaturated fatty acids than from cows feeding on grass silage and zero-grazing, with significant differences in the proportion of vaccenic and rumenic acids. The 18:1 trans-11 to 18:1 trans-10 ratio is proposed as biomarker to identify the milk produced from the management system of grazing cattle. Milk from grazing cows had a greater proportion of lutein than cows eating grass silage, with the zero-grazing system having intermediate values. In conclusion, the mode of grass supply affects fatty acid and antioxidant profiles of milk.

Palmitic acid-enriched fat supplementation alleviates negative production responses during early lactation of Holstein dairy cows

Effects of rumen-protected fat (RPF) on suppressing the negative performance responses in early lactation period of Holstein dairy cows were investigated. Three hundred multiparous Holstein cows (647 ± 16 kg bodyweight and 90 days in milk (DIM)) were randomly housed into three free-stall barns (100 cows per barn) and assigned to the treatments for 90 days, as follows: (1) control (CTL) diet without RPF; (2) calcium salt of palm fatty acids (CaFA) 30 g/kg DM, and (3) fractionated fatty acids of palm oil (FFA) 25 g/kg DM. Cows were fed total mixed ration containing 580 g of concentrate and 420 g of roughage per kilogram DM. Cows fed FFA exhibited a higher (P &lt; 0.05) DM intake and body condition score than did those fed CaFA or CTL diets respectively. Moreover, cows fed the FFA diet showed decreased (P &lt; 0.05) changes to bodyweight at 30 DIM and to body condition score at 60 DIM and increased digestibility of ether extract and neutral detergent fibre. Blood concentrations of triglycerides, cholesterol and glucose were higher (P &lt; 0.05) for cows fed FFA diet than for those fed the other diets, between 4 and 30 DIM, whereas concentrations of non-esterified fatty acids, β-hydroxybutyric acid and urine ketones were lower for cows fed RPF sources (P &lt; 0.05). Relative to CTL diet, CaFA and FFA diets increased (P &lt; 0.05) milk yield and milk fat content at 4–30 DIM. Feeding FFA improved feed efficiency by 8.9% (P = 0.006), between 31 and 60 DIM, compared with CaFA. Inclusion of a palmitic acid-enriched fat supplement in Holstein cow diet increased milk yield and fat content and mitigated the deleterious effects of metabolic disorders during the early lactation period.

Effects of microbial feed additives on feed utilization and growth performance in growing Barki lambs fed diet based on peanut hay

The effects of supplementing diet of growing lambs with microbial feed additive mixture (direct-fed microbial; DFM) based on Saccharomyces cerevisiae, lactic acid bacteria and exogenous enzymes on feed intake, nutrient digestibility, nitrogen (N) utilization, ruminal fermentation, blood chemistry and growth performance were studied. The study was a completely randomized design with 12 growing Barki lambs divided into two groups of six lambs per treatment. Lambs were offered a control diet of peanut hay and concentrates (1:1 dry matter (DM) basis) or the control diet supplemented with DFM at 0.5 g/day (Bactozyme treatment) for 16 weeks. There was no effect on feed efficiency but Bactozyme lambs had increased (p = 0.009) feed intake, average daily gain (p = 0.042) and final body weight (p = 0.047). Bactozyme treatment had greater neutral detergent fiber (p = 0.020) and acid detergent fiber (p = 0.034) digestibility compared with the control treatment. Metabolism experiment showed that the feed additive mixture increased (p<0.05) N intake and N retention. Bactozyme treatment had greater blood total protein (p = 0.027), and globulin (p = 0.025) concentrations compared with the control treatment. It is concluded that supplementing growing Barki lambs with DFM at 0.5 g daily enhanced final body weight gain and fiber digestion without affecting feed efficiency.