Dietary Supplementation with Rumen-Derived Streptococcus macedonicus Improves Growth Performance and Carcass Characteristics of Barki Lambs
by
, , , , ,
Mahmoud M. Shaaban
1,†,
Min Gao
2,†,
Mohamed El-Sherbiny
3,*
,
Ahmed M. Abd El Tawab
3,
Mostafa S. A. Khattab
3,
Mohamed A. Radwan
4
,
Fatma I. Hadhoud
3 and
Yongbin Liu
5,6,* 1
Biological Applications Department, Nuclear Research Center, Egyptian Atomic Energy Authority, Inshas, Cairo 13759, Egypt
2
Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot 010031, China
3
Department of Dairy Science, National Research Centre, 33 Bohouth St., Dokki, Giza 12622, Egypt
4
Department of Animal Production, Faculty of Agriculture, Cairo University, Giza 12613, Egypt
5
Department of Animal Genetics, Breeding, and Reproduction, College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China
6
State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, Inner Mongolia University, Hohhot 010021, China
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Animals 2026, 16(18), 2865; https://doi.org/10.3390/ani16182865
Submission received: 28 July 2026
/
Revised: 6 September 2026
/
Accepted: 9 September 2026
/
Published: 11 September 2026
(This article belongs to the Special Issue Functional Prebiotics and Probiotics: Impact on Animal Growth, Development and Health)
Simple Summary
The use of probiotics is an increasingly attractive strategy for improving livestock productivity while reducing reliance on antibiotic growth promoters. In this study, we evaluated a strain of Streptococcus macedonicus isolated from the rumen of healthy sheep as a potential probiotic for growing Barki lambs. The isolate showed antimicrobial activity against several pathogenic bacteria and a predominantly susceptible antibiotic-response profile. Dietary supplementation with S. macedonicus improved nutrient digestibility and growth performance, resulting in greater body weight gain and better feed conversion efficiency than the control diet. It also increased carcass yield and longissimus muscle area, reduced carcass fat proportion, and improved meat quality traits, including water-holding capacity and redness. No significant treatment-related changes were detected in the measured blood biochemical variables. Both supplementation levels produced favorable responses, but increasing the dose from 1 to 2 g/day did not result in additional statistically significant improvements in the evaluated productive traits. These findings support further evaluation of rumen-derived S. macedonicus as a promising direct-fed microbial for improving the productivity and carcass quality of growing Barki lambs.
Abstract
This study evaluated a rumen-derived Streptococcus macedonicus isolate in Barki lambs using in vitro and in vivo approaches. The isolate was characterized for antibacterial activity and antimicrobial susceptibility. In vitro, a control diet was incubated for 24 h with 0, 0.002, 0.004, 0.008, or 0.016 g of S. macedonicus, and fermentation and digestibility were determined. In vivo, 40 Barki lambs were assigned to four dietary treatments for 210 d: control, control plus 1 g/d commercial probiotic, or control plus 1 or 2 g/d S. macedonicus. Feed intake, nutrient digestibility, growth performance, carcass traits, and meat quality were evaluated. The isolate showed antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and Bacillus cereus. In vitro, S. macedonicus increased dry matter digestibility (52.9% to 56.7%; p = 0.042) and total gas production (p < 0.0001). In vivo, dry matter digestibility increased from 66.3% to 75.2% (p = 0.002). Supplemented lambs had greater final body weight, average daily gain, and an improved feed conversion ratio (p < 0.001). Supplementation also improved carcass yield, dressing percentage, longissimus muscle area, lean proportion, water-holding capacity, and meat redness while reducing carcass fat percentage. Overall, rumen-derived S. macedonicus improved nutrient utilization, growth performance, and carcass and meat quality traits.
