RECENT ADVANCES IN OSTRICH NUTRITION IN SOUTH AFRICA: EFFECT OF DIETARY ENERGY AND PROTEIN LEVEL ON THE PERFORMANCE OF GROWING OSTRICHES

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1 SA-ANIM SCI 22, vol 3: 1 RECENT ADVANCES IN OSTRICH NUTRITION IN SOUTH AFRICA: EFFECT OF DIETARY ENERGY AND PROTEIN LEVEL ON THE PERFORMANCE OF GROWING OSTRICHES Tertius Brand Elsenburg Agricultural Research Centre, Private Bag X1, Elsenburg 767, South Africa tersb@elsenburg.com Kobus Nel, Zanell Brand and Koot van Schalkwyk Oudtshoorn Experimental Farm, P.O. Box 313, Oudtshoorn 662, South Africa Introduction Since the first publication on ostrich nutrition appeared in 1913 (Dowsley & Gardiner, 1913), a considerable amount of research has been conducted on the subject in South Africa. Scientific publications on ostrich nutrition is, however, scarce, since plenty of this information is not published in International Scientific Journals yet. During 1997/1998 the ostrich industry in South Africa reached a low point. Feeding usually constitutes about 7-8% of the total costs of intensive production systems for farm animals and had a major influence on the profitability of an ostrich enterprise as well. Researchers of the Elsenburg Agricultural Research Centre and the Oudtshoorn Experimental farm, in cooperation with the Little Karoo Agricultural Cooperation at Oudtshoorn, therefore conducted several experiments over this period to lower the most important cost item in ostrich production systems, namely the cost of feeding. This was an effort to improve the profitability of intensive ostrich production systems in South Africa. Background Like pigs and poultry, ostriches are monogastric animals. Ostriches are herbivores (plant-eaters) and their digestive systems have adjusted to cope with large amounts of low-quality, fibre-rich plant material (roughage) (Angel, 1996). Fibre-rich material is largely digested and absorbed in the lower digestive tract of monogastric animals. In Figure 1 the capacity of the digestive tracts of three common farm animal species namely chickens, pigs and ostriches, are compared graphically. It is clear that the lower digestive tract of an ostrich is much larger than that of poultry or pigs in relation to the total digestive tract. This larger lower digestive tract is directly associated with the ability of an animal to digest fibrous materials. The lower digestive tract (colon or large intestine plus caecum) of poultry, pigs (Getty, 1975) and ostriches (Bezuidenhout & Van Aswegen, 199) constitutes about 11%, 21% and 61% of the total digestive tract of the different species. Table (replacing Figure 1) The relative length of the small intestine, large intestine (colon) and caecum of the chicken, pig and ostrich (adapted from Getty, 1975 and Bezuidenhout & Van Aswegen, 199) Small Intestine % Large Intestine % Caecum % Ostrich Chicken Pig The type of diet given to ostriches also has an effect on the relative size of the lower digestive tract. In animals fed with fibre-rich feed, the capacity of the colon is larger (Baltmanis et al., 1997). These animals probably adapt to obtain more nutrients from the available diets. An important factor that also influences the digestion of fibre by ostriches, is age. In research by Angel (1996) it was found that three-week old ostrich chickens digest 6.5% of neutral-detergent fibre (NDF) in their diet, while mature animals (at 3 months) could digest 61.5%. Angel (1993) found that ostriches are able to digest fibre as early as the age of 1 to 17 weeks (51.2 and 58.% NDF) almost as efficiently as mature birds (61.6% NDF digestion). Another important factor in the digestion of raw materials by farm animals is the retention time of the feed or rate of passage of the digesta. This is the time it takes for feed to move through the digestive tract of the animal. The

2 SA-ANIM SCI 22, vol 3: 2 longer the rate of passage, the more time there is for the actions of digestive enzymes and microbes, and the more material is digested. The retention time of feed for chickens, pigs and ostriches is presented in Table 1. Table 1 The retention time of feed in digestive tracts of chickens, pigs and ostriches (Ensminger & Olentine, 1978; Swart, 1988) Retention time Species Chickens Pigs Ostriches Time (h) ± 1 ± 3 ± 4 In order to compare the efficiency of digestion of diets for ostriches, pigs and chickens, a survey was conducted in which nine diets with various crude fibre levels were fed to the three animal species (Brand et al., 2a). The results are shown in Figure 2. Energy value (MJ/kg DM) Ostrich ME Pig DE Poultry ME Figure 2 The energy value of the same nine diets fed to ostriches, pigs and chickens (Brand et al., 2a) The research clearly shows that ostriches consistently showed 2% higher energy values for the same raw materials compared to pigs. With higher containing fibre diets ostriches had considerably higher energy values for the same raw materials compared to poultry. The exceptional ability of ostriches to utilize lower quality raw material better than pigs and chickens was clearly illustrated in this study. The ability of the ostrich to utilize lower quality raw material was also clearly indicated by the pioneering work of Swart (1988). This researcher indicated that the ostrich has the ability to digest both cellulose and hemicellulose. It was also established that ostriches could probably obtain 12 to 76% of their energy in the form of volatile fatty acids (the end product of the digestion of fibre-rich feed in the large intestine). With pigs, that are also able to digest fibre fractions (hemicellulose) to a certain extent, energy supply in the form of volatile fatty acids from the lower digestive tract may contribute 1 to 3% to their total energy requirements (Eggum et al., 1982). The lower digestive tract of chickens does not supply any energy to the animal (Hayes, 2). Growth studies with slaughter ostriches To utilize the above-mentioned unique ability of ostriches, various studies were carried out in which more fibre-rich and eventually relatively cheaper diets were evaluated. In a study by Salih et al. (1998) ninety ostriches (18 groups of five each) were fed starter, grower and finisher diets with three energy levels each. Their study indicated better growth rates and feed conversion ratios for birds on the high energy diets during the starter phase. No significant differences were however observed in feed conversion ratio between the high, medium and low energy diets during the grower and finisher phases, which were unexpected and difficult to explain, since high energy diets normally lead to better feed conversion ratios. A high quality lucerne diet was however used as source of roughage, which might have played a role in the utilization of these diets. Growth rates were generally higher on the higher energy diets. A second study was conducted by Brand et al. (2b), in which diets with three energy and three protein/amino acid levels were evaluated. In this case very low-quality roughage was used. Eighteen groups of ostriches of five per group were given diets with energy levels of approximately 9., 1.5 and 12. MJ

3 SA-ANIM SCI 22, vol 3: 3 ME/kg DM and 13, 15 and 17% protein. Diet formulations were done according to requirements and raw material composition values presented in the Elsenburg Ostrich Feed Databasis (Brand, 2). Amino acid compositions were adjusted to correspond with protein levels. Birds were fed from age 4 to 11 months. Bodyweight and feed intake of animals were determined on a monthly basis. The composition of the nine experimental diets is illustrated in Table 2. Table 2 Experimental diets for slaughter ostriches with varying inclusion levels of energy and protein. (Oats bran plus lucerne hay were used mainly as a source of roughage and maize as a source of concentrated feed) (Brand et al., 2b) Low energy diet 13 % protein + (9. MJ ME/kg DM) 15 % protein + 17 % protein + Medium energy diet 13 % protein + (1.5 MJ ME/kg DM) 15 % protein + 17 % protein + High energy diet 13 % protein + (12 MJ ME/kg DM) 15 % protein + 17 % protein + + Amino acid compositions were adjusted to correspond with protein levels. The effect of dietary (energy level) on the production results of ostriches over the experimental period (4 11 months) is presented in Table 3. Table 3 The effect of dietary energy level on the production performance of slaughter ostriches from age 14 to 11 months (± kg living mass) (Brand et al., 2b) Energy level Measurement High Medium Low s.e. Dry matter intake (kg/bird/day) 2.41 a 2.63 a 2.9 b.6 Growth rate (g/bird/day) 313 NS 39 NS 285 NS 11 Feed conversion (kg feed/kg weight increase) 6.79 a 7.45 ab 8.81 b.39 Skin surface (dm²) 138 a 137 ab 134 b 1.2 s.e. Standard Error; NS Non-significant; a,b Indicates significant (P.5) differences Table 4 The effect of protein level on the production performance of slaughter ostriches of age 4 to 11 months (± kg living mass) (Brand et al., 2b) High protein 17% Medium protein 15% Low protein 13% s.e. DM intake (kg/bird/d) 2.21 NS 2.14 NS 2.32 NS.7 Growth rate (g/bird/d) 38 NS 299 NS 3 NS 11 Feed conversion (kg feed/kg 7.52 NS 7.49 NS 8.13 NS.39 weight increase) Skin surfcace (dm²) 138 NS 136 NS 135 NS 1.2 s.e. Standard error; NS Non-significant

4 SA-ANIM SCI 22, vol 3: 4 Bodyweight (kg) High Energy Medium Energy Low Energy Figure 3 The effect of dietary energy on the live weight of ostriches for the growth interval 25 to 9 kg (No significant differences were found) Feed intake (kg/day) High Energy Medium Energy Low Energy Figure 4 The effect of dietary energy levels on the feed intake of ostriches for the growth interval 25 to 9 kg. ( Indicate significant differences) 1 9 Feed conversion ratio (kg feed/kg weight) High Energy Medium Energy Low Energy Figure 5 The effect of dietary energy level on the feed conversion ratio of ostriches for the growth interval 25 to 9 kg. ( Indicate significant differences) Figures 3, 4 and 5 also illustrate the effect of dietary energy level on the bodyweight, feed intake and feed conversion of ostriches from the onset of the study on a monthly basis with increasing age. It is clear from Table 3, as well as Figure 3, that the energy levels of the diet did not affect the growth rate of the slaughter birds in this study. Birds on the low energy diet did, however, consume significantly more feed than birds on the high energy diets, with a consequent feed conversion ratio in terms of kilogram feed per kilogram weight gain for the higher energy diets. The implications of this are illustrated in Table 6 and discussed later. The effect of the protein content of the diet is shown in Table 4. Figures 6 to 8 illustrate the effect of the level of protein inclusion on the bodyweight, feed intake and feed conversion of ostriches from the beginning of the survey on a monthly basis with increasing age. It is clear from Table 8 and Figures 6 to 8 that the protein content of 13 to 17% of the diet had no effect on the production performance of the ostriches

5 SA-ANIM SCI 22, vol 3: 5 for this growth interval. Protein content did, however, significantly affect growth rate between four and five months (± kg). This difference was eliminated again at the following weighing interval (4 6 months). (Figure 6 not reproducible) Figure 6 The effect of dietary protein level on the live weight of ostriches for the growth interval 25 to 9 kg. ( Indicate significant differences) Feed intake (kg/day) High Protein Medium Protein Low Protein Figure 7 The effect of dietary protein level on the feed intake of ostriches for the growth interval 25 to 9 kg ( Indicate significant differences) Feed conversion ratio (kg feed/kg weight High Protein Medium Protein Low Protein Figure 8 The effect of dietary protein level on the feed conversion ratio of slaughter ostriches for the growth interval 25 to 9 kg (No significant differences were found) Conclusions and implications of lower energy and protein diets Young birds Local studies as well as foreign studies indicated that young ostriches perform better up to about three months of age on high-quality diets with relatively low roughage content. Table 5 illustrates the results of a study by Gandini et al. (1986), where young ostriches (up to age eight weeks) received diets with increasing levels of protein. No differences were found in production between diets with 16, 18 or 2% protein, while birds on these diets performed better on these diets compared to those on a 14% protein diet.

6 SA-ANIM SCI 22, vol 3: 6 Table 5 The effect of diet protein level on the intake, growth and feed conversion of young ostriches (Gandini et al., 1986) Production performance Level of protein (%) + Feed conversion Final bodyweight (kg) ADG (g/day) (kg feed/kg mass gain) Green lucerne was provided additionally at 3.5% of intake Growing birds According to Angel (1996) ostriches can utilize roughages well from the age three months. These findings have also been confirmed by recent studies. In the study by Salih et al (1998), where high-quality roughage (lucerne hay) was used in the diets, feed conversion from 12 to 52 weeks of age (±28 15 kg growth interval) was also not significantly or negatively affected by the high roughage level. In the study by Brand et al. (2) where a lower quality roughage (oat middlings with a ME concentration of 6.9 MJ ME/ kg DM and 5% CP) was used, birds on the low energy diets consume more feed relative to birds on higher energy diets. The slaughter birds in this study also used more feed per kilogram weight gain for the growth interval four to 11 months age (± kg growth interval) when utilizing lower energy containing diets compared to the higher energy containing diets. Protein and amino acid levels, as provided in the study (13, 15 and 17%), had no effect on growth performance. Finally, the cost of production is dependent on the total number of units of energy or kilogram of protein consumed per kg live weight gain. In Table 6 the energy and protein consumption (which determine the costs) are calculated for different dietary energy levels. The results clearly show that the energy consumption per kilogram weight gain did not differ between high and low energy containing diets. There was, however, a tendency towards better protein utilization on the low-protein diet. These results may indicate that, depending on production system and the price of raw materials, lower energy diets may play a role in ostrich production systems during the later growth stages. Table 6 Energy and protein consumed by slaughter birds (Calculations based on results found by Brand et al., 2b) Effect of energy level High energy Medium energy Low energy s.e. Feed consumption a 7.45 ab 8.81 b.39 Energy consumption NS 78.3 NS 79.3 NS 4.2 Effect of protein level High protein Medium protein Low protein s.e. Feed consumption NS 7.49 NS 8.13 NS.39 Protein consumption , kg feed consumed/kg liveweight increase; ++ MJ ME consumed/kg liveweight increase +++ NS kg protein consumed/kg liveweight increase Non-significant a,b 1,2 Indicates significant (P.5) differences; Indicates significant (P <.1) differences General remarks Nutritionists still do not agree about the nutritional standards that should be used for ostriches (Brand et al., 1999). Angel (1996) formulated diets on the basis of poultry requirements (chicken ME). Other American nutritionists suggested that the turkey is the best model to use to project the requirements for ostriches. Australian studies indicated that the use of extrapolated poultry values have led to the development of ostrich diets that exceed their requirements. A review published in the Netherlands indicated that recommendations and composition of diets for ostriches still vary considerably. Diverse

7 SA-ANIM SCI 22, vol 3: 7 recommendations regarding the protein content in starter ( %), grower ( %), finisher ( %), as well as maintenance ( %) and breeding diets ( %) are still found, while recommendations for the energy requirements of breeding birds, for example, vary between 7.9 and 1.6 MJ ME (Brand, 1999). Milton et al. (1994), on the other hand, found that wild ostriches select for a high fibre concentration in their diet (24.%) and that the selected plants in wild ostrich diets contain approximately 12% protein. Current information provides general guidelines for the protein, amino acid and energy content of diets for growing ostriches in relation to the relative nutrient requirements during different growth and production stages. It is important to remember that the efficiency of the utilization of a diet depends on how balanced the specific diet is for animals in terms of their requirements for protein, amino acid, energy and other essential nutrients. It is important to remember that diets should be formulated on the principle of least cost. The prices of raw materials in relation to their nutritional value will always determine the final diet composition. Until now only a few growth studies have been undertaken on a scientific basis to evaluate the efficiency of feed utilization of ostriches. Scientific information on the nutrient requirements of ostriches during different growth and production stages is also scarce. This information is essential for the ostrich industry in order to remain competitive and economically viable in the long term. Acknowledgements The Klein Karoo Co-operative at Oudtshoorn and the Technology and Human Resources for Industry Program of the National Foundation of South Africa who financed this studies. References Angel, C.R., Research Update: Age changes in the digestibility of nutrients in ostriches and nutrient profiles in the hen and chick. Proc. Assoc. Avian Vet. p.p Angel, C.R., A review of ratite nutrition. Anim. Feed Sci. Technol. 6, Baltmanis, B., Blue-McLendon, A. & Angel, R., Effect of diet on the ostrich gastrointestinal tract size. Amer. Ostrich: Res. Issue, p.p Bezuidenhoudt, A.J. & Van Aswegen, G., 199. Light microscopic and immunocytochemical study of the gastro-intestinal tract of the ostrich (Struthio camelus). Onderstepoort J. Vet. Res. 57, Brand, T.S., 2. Elsenburg Ostrich Feed Databasis. Elsenburg Agricultural Research Centre, Private Bag X1, Elsenburg, 766, South Africa. Brand, T.S., Brand, Z., Nel, C.J., Van Schalkwyk, S.J. & Salih, M., Ostrich nutrition: Review of recent research results. Proc. Ostrich Information, 3 November 1999, p.p (In Afrikaans). Brand, T.S., Van der Merwe, J.P., Salih, M. & Brand, Z., 2a. Comparison of ostrich energy values with energy values obtained by pigs, poultry as well as ruminant in vitro values. Proc. 58 th Anim. Production Conf., Kwazulu-Natal, July 2, p.p Brand, T.S., Nel, C.J. & Van Schalkwyk, S.J., 2b. The effect of dietary energy and protein level on the production of growing ostriches. Proc. 58 th Anim. Production Conf., Kwazulu-Natal, July 2, p.p Dowsley, W.G. & Gardiner, C., Ostrich Foods and Feeding. The Publishers, P.O. Box 118, Grahamstown, South Africa. Eggum, B.O., Thorbek, G., Beames, R.M., Chwalibog, A. & Henckel, S., Influence of diet and microbial activity in the digestive tract on digestibility, and energy metabolism in rats and pigs. Brit. J. Nutr. 48, Ensminger, M.E. & Olentine, C.G., Feeds and Nutrition Complete. The Ensminger Publishing Co., USA. Gandini, G.C.M., Burroughs, R.E.J. & Ebedes, H., Preliminary investigation into the nutrition of ostrich chicks (strutio camelus) under intensive conditions. J. S. Afr. Vet. Assoc. March 1986, Getty, R., The Anatomy of the Domestic Animals (fifth ed.). WB Saunders Co., London. Hayes, J.P., 2. University of Stellenbosch, Private Bag X1, Matieland 762. Personal comm. Milton, S.J., Dean, W.R.J. & Siegfried, W.R., Food selection by Ostrich in South Africa. J. Wildlife Management. 58, Salih, M.E., Brand, T.S., Van Schalkwyk, S.J., Blood, J.R., Pfister, B., Brand, Z. & Akbay, R., The

8 SA-ANIM SCI 22, vol 3: 8 effect of dietary fibre level on the production of growing ostriches. Proc. Second Int. Ratite Congr., Oudtshoorn, South Africa Sept. 1998, pp Swart, D., Studies on the hatching, growth and energy metabolism of the ostrich chick (Struthio camelus) PhD-thesis. University of Stellenbosch, South Africa.