Study on Determining Appropriate Protein Levels in the Diet of Naked Neck Chickens in Nghe An

Available online at www.rajournals.in RA JOURNAL OF APPLIED RESEARCH ISSN: 2394-6709 DOI:10.47191/rajar/v11i10.06 Volume: 11 Issue: 10 October 2025 International Open Access Impact Factor8.553 Page no.- 884-889 884 Le Minh Thanh1, RAJAR Volume 11 Issue 10 October 2025 Study on Determining Appropriate Protein Levels in the Diet of Naked Neck Chickens in Nghe An Le Minh Thanh1, Nguyen Thi Linh1, Pham Thai Hoang1, Pham Hai Ninh2 1Nghe An Science and Technology Application Center 2Institute of Animal Husbandry ARTICLE INFO ABSTRACT Published Online: 10 October 2025 Corresponding Author: Le Minh Thanh This study aimed to determine the appropriate dietary protein levels for commercial Naked Neck chickens in Nghe An province, Vietnam. A total of 450 one-day-old chicks were randomly assigned to three treatments with different crude protein levels: 17%, 18%, and 19% (0–8 weeks), and 15%, 16%, and 17% (9–16 weeks), while metabolizable energy was kept constant at 3000 Kcal/kg. Growth performance, survival rate, and body weight were evaluated over 16 weeks. The results showed that protein levels did not significantly affect survival, which remained high (93.33– 94.67%). However, body weight was strongly influenced by dietary protein content. Chickens fed with higher protein diets (19% for 0–8 weeks and 17% for 9–16 weeks) consistently achieved the highest body weights at all stages, while those on the lowest protein diets (17% and 15%) had the lowest weights. These findings suggest that a dietary protein level of 19% in the starter phase and 17% in the grower phase is most suitable for optimizing growth performance in commercial Naked Neck chickens, without compromising survival. KEYWORDS: Naked Neck chicken, dietary protein, growth performance, survival rate, body weight, indigenous breed 1. INTRODUCTION Protein nutrition in poultry production is an important nutritional indicator that directly affects health, productivity, and product quality. Broiler chickens require relatively high levels of protein in their diet to support rapid growth. Part of this weight gain is the growth of protein-rich tissues. Therefore, feed rations need to provide appropriate protein levels according to breed and growth stage in order to achieve optimal performance. Determining suitable nutritional diets for each breed and production stage helps improve productivity, reduce production costs, and increase economic efficiency. With the growing demand for indigenous chicken meat, producers must focus on nutrition to optimize their potential. Nutrient absorption, especially crude protein, plays an important role in the productivity and meat quality of broiler chickens (Mir et al., 2017). The Naked Neck chicken is an indigenous breed originating from Hanh Dich commune, Que Phong district, Nghe An province. It is characterized by diverse feather colors—males are mostly red-brown while females are brown with black spots. Both sexes share the distinctive feature of a featherless neck. Naked Neck chickens adapt well to mountainous terrain and natural climate conditions, have high disease resistance, and produce tasty meat and eggs. However, no research has yet been conducted on suitable nutrition for commercial Naked Neck chickens. For that reason, we conducted the research project: “Study on determining appropriate protein levels in the diet of commercial naked neck chickens in Nghe An”. II. MATERIAL AND METHODS 2.1. Material - Research materials: One-day-old naked-neck chickens for the experiment: 50 chicks/lot, 3 lots, 3 replications. Total: 450 chicks. - Research location: Nghe An Science and Technology Application Center, Nghe An province, Vietnam. - Research period: April 20, 2024 – August 9, 2024. “Study on Determining Appropriate Protein Levels in the Diet of Naked Neck Chickens in Nghe An” 885 Le Minh Thanh1, RAJAR Volume 11 Issue 10 October 2025 Figure 1: One-day-old naked-neck chickens 2.2. Methods * Experimental Diets: The experimental diets were designed following a completely randomized single-factor model: - Stage 0–8 weeks of age: three protein levels (Lot 1: 17%, Lot 2: 18%, Lot 3: 19%), with the same energy level of 3000 Kcal/kg. - Stage 9–16 weeks of age: three protein levels (Lot 1: 15%, Lot 2: 16%, Lot 3: 17%), with the same energy level of 3000 Kcal/kg. Each stage in the lots was replicated three times. The experimental chickens were reared on litter in naturally ventilated housing. Husbandry, veterinary hygiene, and disease prevention procedures were applied according to the Ri chicken raising protocol. All experimental lots were uniform in breed, care, and sanitary conditions, differing only in the experimental factor (feed). Objective: To determine the appropriate protein level in diets for commercial naked-neck chickens at three levels, as follows: Table 1: Experimental design scheme Indicator Lot 1 Lot 2 Lot 3 Stage 0–8 weeks KP1 KP2 KP3 ME (kcal/kg) 3000 3000 3000 Protein (%) 17 18 19 Stage 9–16 weeks KP1 KP2 KP3 ME (kcal/kg) 3000 3000 3000 Protein (%) 15 16 17 Number of chicks/replication: 50, replications: 3. Total chicks: 450 Table 2: Nutritional values for naked-neck chickens (1–8 weeks of age) Nutrient Lot 1 Lot 2 Lot 3 ME (Kcal/kg) 3000 3000 3000 Protein (%) 17 18 19 Crude fat (%) 4.44 4.58 4.62 Crude fiber (%) 2.88 2.84 2.85 Calcium (%) 0.81 0.92 0.98 Phosphorus (%) 0.52 0.57 0.59 Lysine (%) 0.89 0.96 1.03 Methionine (%) 0.51 0.53 0.54 Table 3: Nutritional values for naked-neck chickens (9–16 weeks of age) Nutrient Lot 1 Lot 2 Lot 3 ME (Kcal/kg) 3000 3000 3000 Protein (%) 15 16 17 “Study on Determining Appropriate Protein Levels in the Diet of Naked Neck Chickens in Nghe An” 886 Le Minh Thanh1, RAJAR Volume 11 Issue 10 October 2025 Crude fat (%) 4.27 4.42 4.48 Crude fiber (%) 3.06 3.05 3.12 Calcium (%) 0.99 1.10 1.11 Phosphorus (%) 0.60 0.65 0.65 Lysine (%) 0.76 0.83 0.90 Methionine (%) 0.57 0.59 0.61 * Monitoring indicators: The monitoring indicators were determined according to TCVN 13474-1:2022 – Part 1: Poultry breeds. * Data analysis methods: Experimental data were analyzed statistically by ANOVA using the GLM procedure in Minitab 16.0 software. The results are presented as mean values ± standard error (SE). Tukey’s test was applied to compare mean values at a 95% confidence level. Differences were considered statistically significant at P < 0.05. 3. RESULTS AND DISCUSSION 3.1. Effects of protein levels on the survival rate of commercial naked neck chickens We conducted a study to evaluate the effects of protein levels on the survival rate of commercial naked neck chickens across weeks of age. The results are presented in Table 4. Table 4: Survival rate of commercial naked neck chickens across weeks of age (%) Week of age Lot 1 Lot 2 Lot 3 01 day-old 150 (100.00%) 150 (100.00%) 150 (100.00%) 1 week 147 (98.00%) 147 (98.00%) 147 (98.00%) 2 weeks 142 (94.67%) 144 (96.00%) 143 (95.33%) 3 weeks 141 (94.00%) 141 (94.00%) 143 (95.33%) 4–15 weeks 140 (93.33%) 141 (94.00%) 142 (94.67%) 16 weeks 140 (93.33ᵃ) 141 (94.00ᵃ) 142 (94.67ᵃ) Note: Mean values with different superscript letters in the same row are significantly different (P<0.05); otherwise, they are not. From Table 4, it can be observed that the survival rate of commercial naked neck chickens was relatively high and stable throughout the weeks of age. Mortality mainly occurred during the early weeks and gradually decreased in later weeks. Overall, Lot 3 had the highest survival rate at 94.67%, followed by Lot 2 at 94.00%, and Lot 1 at 93.33%. However, statistical comparison showed no significant differences among the groups (P>0.05). Thus, the survival rate of commercial naked neck chickens up to 16 weeks of age ranged from 93.33% to 94.67%. Nguyen Thanh Son et al. (2017) conducted an experiment on VP34 and VP35 chickens with different protein levels and reported survival rates ranging from 90.67% to 92.00% from day-old to 16 weeks of age. These results were lower than those found in our study on commercial naked neck chickens over the same period. Pham Cong Thieu et al. (2020), in a detailed genetic evaluation of naked neck chickens, reported a survival rate of 94.48% up to 16 weeks of age, which is comparable to our study results for the same stage. 3.2. Effects of protein levels on the body weight of commercial naked neck chickens To determine the effects of different protein levels in the diet on the growth performance of the experimental chickens, we measured their body weight weekly. The results are presented in Table 5. * Stage 0–4 weeks of age: Table 5: Effects of protein levels in feed on the body weight of commercial naked neck chickens from 1 day-old to 4 weeks of age (g) Week of age Lot 1 (Protein 17%) Lot 2 (Protein 18%) Lot 3 (Protein 19%) 01 day-old 28.98 ± 2.35 (CV 8.11%) 29.07 ± 2.21 (CV 7.60%) 29.75 ± 2.18 (CV 7.32%) 1 week 53.81 ± 6.85 (CV 11.68%) 58.03 ± 6.40 (CV 11.03%) 60.14 ± 6.38 (CV 10.61%) 2 weeks 92.08 ± 10.95 (CV 11.89%) 97.64 ± 12.18 (CV 11.89%) 104.20 ± 12.18 (CV 11.69%) “Study on Determining Appropriate Protein Levels in the Diet of Naked Neck Chickens in Nghe An” 887 Le Minh Thanh1, RAJAR Volume 11 Issue 10 October 2025 3 weeks 148.94 ± 18.27 (CV 12.27%) 156.95 ± 19.38 (CV 12.35%) 165.87 ± 20.29 (CV 12.23%) 4 weeks 217.96ᶜ ± 28.28 (CV 12.97%) 227.45ᵇ ± 29.02 (CV 12.76%) 237.39ᵃ ± 29.93 (CV 12.61%) Note: Mean values with different superscript letters in the same row are significantly different (P<0.05); otherwise, they are not. At the beginning of the experiment (day-old), the chickens were relatively uniform (average ranging from 28.99 g to 29.77 g). This body weight was consistent with the findings of Pham Cong Thieu et al. (2020), who reported the weight of naked neck chickens at 1 day-old was 29.40 g/bird. However, it was lower than that of naked neck chickens raised at Lien Ninh Experimental Farm (31.87 g/bird) (Ho Xuan Tung et al., 2020). At the end of the 0–4 week stage, body weight in Lot 2 and Lot 3 began to increase more rapidly compared to Lot 1. Specifically, at 4 weeks of age, the body weight of chickens in Lot 3 was 237.39 g, Lot 2 was 227.45 g, and Lot 1 was the lowest at 217.96 g. The differences in body weight at 4 weeks were statistically significant (P<0.05). Pham Cong Thieu et al. (2020) reported that naked neck chickens had an average body weight of 255.83 g/bird at 4 weeks of age. Ho Xuan Tung et al. (2020) found that naked neck chickens raised at Lien Ninh Experimental Farm weighed 243.06 g/bird at 4 weeks. Ngo Thi Kim Cuc and Nguyen Cong Dinh (2017), in their study on appropriate protein levels for Mong chickens, reported a body weight of 274.33–293.00 g/bird at 4 weeks, indicating that naked neck chickens were lighter than Mong chickens. * Stage 5–8 weeks of age: Figure 3: Naked Neck female chicken at 8 weeks old This is the period when chickens experience the fastest body weight gain. During this stage, we observed noticeable differences in body weight among dietary treatments. At the end of 8 weeks, Lot 3 reached the highest Figure 2: Naked Neck chicken at 4 weeks old “Study on Determining Appropriate Protein Levels in the Diet of Naked Neck Chickens in Nghe An” 888 Le Minh Thanh1, RAJAR Volume 11 Issue 10 October 2025 body weight (634.15 g), followed by Lot 2 (607.94 g), and the lowest was Lot 1 (596.86 g). Statistical analysis showed that the difference in body weight between Lot 1 and Lot 3 was significant (P<0.05). Thus, during this stage, chickens fed diets containing 19% protein grew the fastest. Pham Cong Thieu et al. (2020) reported that naked neck chickens at 8 weeks of age weighed 661.33 g/bird for males and 557.67 g/bird for females, with an average of 609.50 g/bird, which was comparable to the results in our study on commercial naked neck chickens. Ho Xuan Tung et al. (2020) found that naked neck chickens raised at Lien Ninh Experimental Farm had an average body weight of 665.10 g/bird at 8 weeks, higher than the results of our experimental chickens. Table 6: Effects of protein levels in feed on the body weight of commercial naked neck chickens from 5 to 8 weeks of age (g) Week of age Lot 1 (Protein 17%) Lot 2 (Protein 18%) Lot 3 (Protein 19%) 5 weeks 297.43 ± 39.92 (CV 13.42%) 305.53 ± 40.63 (CV 13.30%) 319.68 ± 42.04 (CV 13.15%) 6 weeks 387.21 ± 52.55 (CV 13.57%) 394.40 ± 54.84 (CV 13.91%) 411.90 ± 56.19 (CV 13.64%) 7 weeks 484.21 ± 68.83 (CV 14.22%) 494.89 ± 70.54 (CV 14.25%) 517.64 ± 72.91 (CV 14.08%) 8 weeks 596.86ᵇ ± 89.40 (CV 14.98%) 607.94ᵇ ± 89.27 (CV 14.68%) 634.15ᵃ ± 96.46 (CV 15.21%) Note: Mean values with different superscript letters in the same row are significantly different (P<0.05); otherwise, they are not. * Stage 9–16 weeks of age: Figure 4: Naked Neck male chicken at 16 weeks old During this period, chickens began to grow more slowly. At 16 weeks of age, the highest body weight was observed in Lot 3 (1288.2 g), followed by Lot 2 (1226.5 g), and the lowest was Lot 1 (1185.5 g). Statistical analysis revealed that body weights in Lot 1 and Lot 3 differed significantly (P<0.05), while there was no significant difference between Lot 1 and Lot 2 (P>0.05). Therefore, diets with 17% protein resulted in the highest body weight at 16 weeks, suggesting this level was the most appropriate. Pham Cong Thieu et al. (2020), in a detailed genetic evaluation of naked neck chickens, reported an average body weight of 1062.65 g/bird at 16 weeks (males and females combined), which was lower than in our study. Although both studies involved naked neck chickens, our results showed higher weights at 16 weeks, likely due to better care and feeding conditions compared to conservation flocks at the local level. Ho Xuan Tung et al. (2020) reported that naked neck chickens raised at Lien Ninh Experimental Farm had a body weight of 1656.00 g/bird at 16 weeks, higher than the commercial naked neck chickens in our experiment. “Study on Determining Appropriate Protein Levels in the Diet of Naked Neck Chickens in Nghe An” 889 Le Minh Thanh1, RAJAR Volume 11 Issue 10 October 2025 Table 7: Effects of protein levels in feed on the body weight of commercial naked neck chickens from 9 to 16 weeks of age (g) Week of age Lot 1 (Protein 15%) Lot 2 (Protein 16%) Lot 3 (Protein 17%) 9 weeks 693.93 ± 100.60 (CV 14.50%) 708.72 ± 99.30 (CV 14.01%) 738.52 ± 106.51 (CV 14.42%) 10 weeks 783.14 ± 109.49 (CV 13.98%) 800.35 ± 108.60 (CV 13.57%) 834.12 ± 115.89 (CV 13.89%) 11 weeks 866.00 ± 118.21 (CV 13.65%) 886.30 ± 119.20 (CV 13.45%) 923.80 ± 126.10 (CV 13.66%) 12 weeks 941.60 ± 126.40 (CV 13.43%) 965.40 ± 126.40 (CV 13.09%) 1007.90 ± 135.00 (CV 13.40%) 13 weeks 1010.50 ± 132.80 (CV 13.14%) 1038.40 ± 133.80 (CV 12.88%) 1082.30 ± 140.80 (CV 13.01%) 14 weeks 1073.00 ± 138.60 (CV 12.92%) 1105.80 ± 139.90 (CV 12.65%) 1155.40 ± 146.10 (CV 12.65%) 15 weeks 1131.10 ± 143.20 (CV 12.66%) 1168.70 ± 147.50 (CV 12.62%) 1221.90 ± 150.00 (CV 12.27%) 16 weeks 1185.50ᵇ ± 146.10 (CV 12.32%) 1226.50ᵇ ± 152.20 (CV 12.41%) 1288.20ᵃ ± 155.00 (CV 12.03%) Note: Mean values with different superscript letters in the same row are significantly different (P<0.05); otherwise, they are not. Thus, chickens fed with different protein levels during this stage did not show large variations in body weight. However, from 5 to 16 weeks, body weight differences became more pronounced: the growth curve of Lot 1 consistently remained the lowest, while the growth curve of Lot 3 increasingly diverged from those of Lot 2 and Lot 1. 4. CONCLUSION - Different protein levels in the diet did not affect survival rate. The survival rate ranged from 93.33% to 94.67%. - At the end of the trial, group 3 with protein levels of 19% (0–8 weeks) and 17% (9–16 weeks) achieved the highest body weight, while group 1 with 17% (0–8 weeks) and 15% (9–16 weeks) had the lowest. Acknowledgements The results presented in this report are part of the scientific and technological project 'Exploitation and development of the Naked Neck chicken genetic resources in some North Central provinces'. The authors thank the Ministry of Science and Technology for their support. REFERENCES 1. 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