Effects of proportions of elephant grass (Pennisetum purpureum) in diet on growth performance and feed conversion ratio for commercial ostrich under tropical conditions

Ha Xuan Bo, Nguyen Thanh Cong¹, Do Duc Luc, Dang Thuy Nhung and Nguyen Thi Hoa¹

Faculty of Animal Science, Vietnam National University of Agriculture
hxbo@vnua.edu.vn
¹ Thuy Phuong Poultry Research Center, National Institute of Animal Sciences

Abstract

This study aimed to evaluate the effects of the replacement of elephant grass in the diet on the growth performance and feed conversion ratio of commercial ostriches. This study was conducted at Ostrich Breeding Research Station, Thuy Phuong Poultry Research Center, National Institute of Animal Science, in Ba Vi district, Hanoi, Vietnam from June 2022 to February 2023. A total of 176 commercial ostriches (88 females and 88 males) of 4 months of age were identified individually by the number on their heads and necks and randomly allocated into one of three dietary treatments (EG10, EG15,EG20). The dietary treatments contained elephant grass and concentrate feed, including (90% concentrate feed and 10% elephant grass), (85% concentrate feed and 15% elephant grass) and (90% concentrate feed and 10% elephant grass). The numbers of ostrich for (EG 10, EG15 and EG20). were 58 (28 males and 30 females), 59 (30 males and 29 females), and 59 (30 males and 29 females), respectively. The experiment was lasted for 9 months and divided into two phases, including (1) growing (4 to 8 months of age) and (2) finishing (9 to 12 months of age). In the growing phase, the final body weight (FBW), but improved the daily weight gain (DWG), and daily feed intake (DFI) of commercial ostriches. In the finishing phase, increasing the levels of elephant grass in the diets affects initial body weight (IBW), FBW, and DWG, and increased DFI and FCR. A similar trend was observed for FBW, DFI and FCR for the experimental period from 4 to 12 months of age. Increasing the proportion of elephant grass in the diet improved FBW, DWG, and FCR of commercial ostriches from 4 to 12 months of age.

Keywords: elephant grass, ostrich, production performance, Vietnam

Introduction

In Vietnam, ostriches have been imported and reared at the Ostrich Breeding Research Station, Thuy Phuong Poultry Research Center, National Institute of Animal Science, in Ba Vi district, Hanoi for more than 20 years (Tien et al 2007a). According to the General Statistics Office (GSO 2021), ostrich in Vietnam currently has over 16,000 heads. The ostrich could use forage sources and adapt to different ecological regions, especially in hot and dry climates. Therefore, they are raised in almost all regions but mainly in the central and northern regions of Vietnam. Additionally, ostrich meat is red meat and ideal for a healthy diet due to its low fat and cholesterol content (Poławska et al 2011).

Adequate and appropriate nutrition values in the diet play an important role in the successful growth and reproduction of ostriches. The information on nutritive requirements and forage intake of ostriches under grazing conditions is important for farmers and nutritionists to provide the essential diets for these animals.

The nutrient requirements of ostriches in Vietnam in recent years have been investigated (Tien et al 2007a, b; Hoa and Giang 2017; Hoa et al 2017). While the studies on the nutrient of ostriches in Vietnam in recent years are quite limited. According to our knowledge, the feed for poultry is used for ostriches, there is no specialized feed for ostriches.

Information on the effects of different proportions of elephant grass (Pennisetum purpureum) and concentrate feed in the diet of commercial ostriches in Vietnam has not previously been reported. Therefore, the study of using different proportions of elephant grass and concentrate feed in the diet in Vietnam, especially in commercial ostriches production is essential. This study aimed to evaluate the effects of the replacement of elephant grass at different levels in the diet on the growth performance and feed conversion ratio of commercial ostriches under tropical conditions in Vietnam.

Materials and methods

Experimental design, animals and diets

This experiment was conducted on 176 commercial ostriches (88 females and 88 males) of 4 months of age at Ostrich Breeding Research Station, Thuy Phuong Poultry Research Center, National Institute of Animal Science, in Ba Vi district, Hanoi, Vietnam from June 2022 to February 2023. The ostriches were identified individually by the number on their heads and necks and randomly allocated into one of three dietary treatments (EG20, EG 15 and EG10). In each treatment, there were 3 replicates. The numbers of ostrich for EG10, EG 15 and EG20 were 58 (28 males and 30 females), 59 (30 males and 29 females) and 59 (30 males and 29 females), respectively. The experiment was divided into two phases (growing and finishing). At the growing phase (4-8 months), ostriches were raised from 4 months to 8 months of age with a body weight of 33.0 ± 3.15 and 80.0 ± 7.03 kg, respectively. At the finishing phase (9-12 months), ostriches were raised from 9 months to 12 months of age with a body weight of 87.3 ± 7.47 kg and 104 ± 8.16 kg, respectively. The males and females were raised in the same pen according to the grazing method. They were access to feed and water ad libitum. The animals were vaccinated according to the farm procedure.

Diets

The dietary treatments contained elephant grass (EG) and concentrate feeds, including (80% concentrate feed and 20% elephant grass), (85% concentrate feed and 15% elephant grass) and (90% concentrate feed and 10% elephant grass). The diets were formulated and are detailed in Table 1.

The chemical compositions of diets were analyzed at the Department of Animal Feeds and Products analysis of the National Institute of Animal Sciences, and nutrient composition was analyzed according to Vietnamese National Standards (TCVN) of Ministry of Science and Technology (MST). Dry matter (DM), crude protein (CP), calcium (Ca), phosphorus (P), lipids, and crude fibers (CF) were estimated according to TCVN 4326:2001 (MST 2001a), TCVN 4328: 2007 (MST 2007a), TCVN 1526-1: 2007 (MST 2007b); TCVN 1525:2001 (MST 2001b), TCVN 4331:2001 (MST 2001c) and TCVN 4329:2007 (MST 2007c), respectively. The chemical compositions of diets are presented in Table 2 according to phase and treatment.

Data collection

Body weight was individually measured at the initial and final fattening of each phase by the Mettler Toledo scale. Body weight gain (BWG) was calculated by the difference between final (FBW) and initial body weight (IBW). Average daily gain (ADG) was based on BWG and fattening days. Feed consumption was recorded daily for each pen. The cumulative feed consumption during the fattening period was considered as feed intake (FI). While the feed conversion ratio (FCR) was calculated from the body weight gain and feed intake.

Statistical analyses

For IBW, FBW, and ADG, the effects of diet, sex, and interaction between these factors were tested using a statistical linear model (1) below:

Y_ijk = µ + DIET_i + Sex_j + DIET_i *Sex_j + e_ijk (1)

Where, Y_ijk = IBW, FBW, or ADG of ostrich kth, sex jth, and DIET ith; µ = overall mean; DIET_i = fixed effect of diet ith (EG20, EG 15 and EG10); Sex_j = fixed effect of sex j (female and male); DIET_i*Sex_j = interaction between diet and sex; e_ijk = residual errors.

For FI and FCR, statistical model 1 was used without sex and interaction effects. The pairwise comparison between means was performed using Tukey’s HSD test. Statistical parameters, arithmetic mean (Mean), and standard deviation (SD). A significant difference was declared p<0.05. The data were performed using lm() function of R software (R version 4.2.2, R Core Team (2022)).

Results

Production performance and feed conversion ratio in the growing phase

The production performance and feed intake of commercial ostriches in the growing phase are shown in Table 3. In this phase, increasing proportions of elephant grass in the diets did not affect FBW (p>0.05), while improved DWG of commercial ostriches from 4 to 8 months of age (p<0.05). Additionally, increasing the amounts of elephant grass in the diets also increased EGI, CFI, and DFI in commercial ostriches from 4 to 8 months of age (p<0.0001). The diet with 15% EG had the highest DWG (398 g), and the lowest FCR (5.14 kg)

Production performance and feed conversion ratio in the finishing phase

The effects of diets on growth performance and feed conversion ratio of commercial ostriches in the finishing phase are shown in Table 4. Increase of elephant grass in the diets led to an increase in IBW (p<0.05), FBW (p<0.0001), and DWG (p <0.05) of commercial ostriches from 9 to 12 months of age. A similar trend was observed for EGI, CFI, and DFI of commercial ostriches from 9 to 12 months of age (p<0.0001). Additionally, using a diet with 15% elephant grass had the highest FBW (106 kg), and the lowest FCR (11.5 kg) among three diets (Table 4).

Production performance and feed conversion ratio of commercial ostriches from 4 to 12 months of age

Effects of proportion elephant grass in the diet on production performance and feed conversion ratio of commercial ostriches from 4 to 12 months of age are shown Table 5, Figure 1.

Increasing proportions of elephant grass in the diets did not affect IBW (p>0.05), while improved FBW, DWG of commercial ostriches (p<0.001). Additionally, increasing the levels of elephant grass in the diets also increased EGI, CFI, DFI, and FCR in commercial ostriches (p<0.0001) from 4 to 12 months of age.

A	B
C
Figure 1. Effects of the proportion of elephant grass in the diet on (A) Total feed intake, (B) Average daily gain (ADG) and (C) Feed conversion ratio (FCR) of ostriches from 4 to 12 months of age

Discussions

The results of our study indicated that increasing the amounts of elephant grass in the diets improved FBW, and DWG while increasing DFI and FCR (Figure 1) of commercial ostriches from 4 to 12 months of age. There was a linear increase of DFI and FCR when the increase of proportion of elephant grass was in the diets. Using a diet with 15% elephant grass could improve the final body weight, daily weight gain, and feed conversion ratio of commercial ostriches. Our results are in agreement with the previous studies that demonstrated the positive effects of the proportion of forage in diets on the overall performance of ostriches (Swart and Kemm 1985; Cilliers et al 1998; Hoa and Giang 2017; Hoa et al 2017).

Swart and Kemm (1985) reported that FBW, DWG, and FCR of ostriches with a live weight between 60 to 110 kg were significantly affected by dietary supplies of three levels of lucerne (67, 57, and 35%). The diets supplied 35% lucerne had the best DWG (235 g/day) and FCR (10 kg).

The results reported by Cilliers et al (1995) showed that the FCR of ostriches were 3.8, 5.5, and 10 kg for the period from 4 to 6 months of age, from 6 to 10 months of age, and from 10 to 14 months of age, respectively. Cilliers et al (1998) confirmed that maize silage is a source of nutrient supply for growing ostriches (50-70 kg). These authors also suggested that poor-quality fiber sources such as wheat straw can replace 20% of lucerne meals without reducing the production of ostriches.

Forage intake for ostriches (50 kg live weight) grazing Rhodes grass, Kikuyu grass, and white clover pastures were from 648 to 858 g/day, and daily gain from 248 to 299 g during 84 days (Farrell et al 2000).

Three experiments were conducted by Tien et al (2007b) to determine a diet suitable for ostriches from 0 to 3 months of age. The authors reported that a diet with 50% forage and 50% concentrate feed was the best for ostriches from birth to 3 months of age.

Two feeding methods were conducted by Hoa et al (2017) to evaluate the economic efficiency and meat quality of ostriches when they were fed the same diet with a proportion of elephant grass of 20%. The results reported by Hoa et al (2017) showed that the FBW and ADG of ostriches with a live weight between 88.7 and 104.8 kg feeding in a diet mixing green forage and concentrate feed were higher than those being green forage and concentrate feed separately. FBW of ostriches in our study was the same as that reported by Hoa et al (2017), whereas FCR was higher. Similar results were reported by Hoa and Giang (2017), who demonstrated better FBW of commercial ostriches fed in a diet mixing green forage and concentrate feed.

Conclusion

• Increasing the proportion of elephant grass in the diet improved FBW, DWG, and FCR of commercial ostriches from 4 to 12 months of age. Using a diet with 15% elephant grass could improve the final body weight, daily weight gain, and feed conversion ratio of commercial ostriches.

Acknowledgment

The study was conducted in the framework of a project entitled “Determine the metabolizable energy value of some common forage, and determine the proportion of forage and concentrate feed in the diets for ostriches” granted by the Ministry of Agriculture and Rural Development, Vietnam. The authors thank the owner, technicians, and workers who participated in and supported this study.

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