Problem statement:
Chicken farming is a traditional and long-standing occupation in Vietnam. Currently, the demand for chicken consumption has increased sharply, leading to the emergence of many large-scale industrial chicken farms. However, problems related to food safety and hygiene in chicken farming are on the rise (Trần Anh Tuyên et al., 2019). Nowadays, probiotic preparations are increasingly receiving attention because the use of antibiotics in farming to stimulate growth is banned to ensure food safety (Phạm Kim Đăng et al.). Using probiotics to supply beneficial bacteria brings great benefits in chicken farming. Probiotics help maintain the balance of gut microbiota, stimulate metabolism of feed to increase digestive enzyme activity, improve digestion, stimulate the immune system, enhance the natural immunity of the gut, and promote secretion and immunity. Probiotics are supplements of beneficial live microorganisms in feed aimed at improving the balance of intestinal microbiota in favor of the host (Perdigon et al., 1999). Probiotics also prepare the body’s responses better to stress factors in the farming environment (Blok et al., 2002). Lactobacillus preparations are recommended to enhance the immune system, balance gut microbiota, inhibit harmful microbes, support digestion and nutrient absorption in chickens, thereby helping chickens to stay healthy and develop better. To provide more evidence and scientific basis for these effects, this study was conducted to evaluate the influence of Lactobacillus preparations on biological safety during broiler chicken farming.

2. MATERIALS AND METHODS

2.1 Materials and duration
The experiment was conducted in Chau Thanh district, An Giang province, using probiotic preparations containing Lactobacillus bacteria.

Summary:
The experiment was conducted on a chicken farm in Chau Thanh district, An Giang province to evaluate the effect of supplementing probiotics containing Lactobacillus plantarum and Lactobacillus acidophilus on the productivity of broiler chickens aged 1 to 8 weeks. The experiment included 3 treatments: control (no probiotic supplementation), treatment 1 (supplemented with probiotic containing Lactobacillus plantarum), and treatment 2 (supplemented with probiotic containing Lactobacillus acidophilus). Results showed that powdered Lactobacillus plantarum and Lactobacillus acidophilus preparations had a significant impact on monitored indicators including cumulative growth, absolute growth, feed conversion ratio, weight gain, feed consumption, and survival rate. Probiotic supplementation effectively improved productivity and health in broiler chicken farming.

2.2 Methods
Local chickens (Ga Noi) aged 1 to 8 weeks were fed a mixed feed supplemented with probiotic preparations containing Lactobacillus sp. The experiment was arranged in a completely randomized design with 5 replicates, each replicate consisting of 10 chickens with a male-to-female ratio of 1:1. Chickens were raised under the same conditions using semi-intensive farming with identical care, hygiene, and disease prevention protocols across treatments.

The treatments were:

• Control (C): chickens fed 100% homemade feed without probiotics, supplemented with antibiotics for common disease treatment;
• Treatment 1 (T1): chickens fed homemade mixed feed supplemented with powdered probiotic containing Lactobacillus plantarum at 0.5% (5g probiotic/kg feed, sprayed directly onto feed);
• Treatment 2 (T2): chickens fed homemade mixed feed supplemented with powdered probiotic containing Lactobacillus acidophilus at 0.5% (5g probiotic/kg feed, sprayed directly onto feed).

Monitored parameters (based on Bùi Hữu Đoàn, 2011) included:

• Survival rate (SR): SR = Number of surviving individuals / Initial total number of individuals.
• Cumulative growth: chickens weighed every 2 weeks from birth to 8 weeks old, using an electronic scale with 0.01g accuracy.
• Relative and absolute growth: calculated by common methods.
• Feed conversion ratio (FCR): FCR = Feed consumed (kg) / Weight gain (kg).
• Weight gain (WG, g/chicken/day): chickens weighed weekly per treatment, then WG calculated. Feed offered and leftovers were weighed daily.
• Disease parameters: determined through clinical symptoms by daily monitoring and recording dead chickens and abnormal symptoms; survival rate, disease incidence, and duration calculated by standard livestock methods.

2.3 Data analysis
Raw experimental data were preliminarily processed in Microsoft Excel 2007, then analyzed by ANOVA using the General Linear Model on Minitab Release 20.3 (Minitab, 2021).

CONCLUSION
Supplementing 5g of powdered probiotic preparations containing Lactobacillus plantarum and Lactobacillus acidophilus in the feed of Ga Noi chickens showed positive effects on cumulative growth, absolute growth, feed conversion ratio, weight gain, and significant differences compared to no supplementation. This enhanced farming efficiency and significantly reduced losses related to survival rate and disease prevention. It is recommended to supplement powdered probiotic preparations containing Lactobacillus plantarum and Lactobacillus acidophilus in Ga Noi chicken feed to improve efficiency and productivity in broiler chicken farming.