Abstract:
313 FURTHER EXPERIMENTS ON CHOICE FEEDING IN POULTRY R.B. CUMMING* SUMMARY Two experiments were conducted to determine if choice feeding could be successfully applied to broilers housed on deep litter,. In the first trial males of two broiler breeds were offered complete diets or a protein concentrate plus either whole wheat, whole sorghum or whole wheat and sorghum. The coccidiostat was administered via the drinking water. Overall growth was very good, with the choice fed broilers herforming as well as those on complete diets. In the second experiment, sexed chickens of two breeds were offered conventional diets or protein concentrate plus whole wheat and sorghum. The coccidiostat was supplied in the diets. Overall growth was depressed in this experiment and the choice fed birds did not perform as well as those fed the complete diets. In both trials the broilers offered whole wheat and whole sorghum showed a marked preference for sorghum over wheat. INTRODUCTION Mastika and Cumming (1981a; 1981b) showed that modern broilers, housed in experimental cages, could adequately select their diets when offered a protein concentrate and untracked wheat or sorghum. These two trials, one in winter and one in summer, were designed to demonstrate if the birds would perform equally well when housed on litter. MATERIALS AND METHODS Housing and Management The birds were housed in an experimental broiler shed, with 32 pens each measuring 300cmx240cm in which 100 day-old chickens were placed. Heating was by means of electric hover brooders around which a metal guard was placed for the first five days. Feed was supplied in three tubular feeders and water in two plastic water fonts per pen for the first five days. Thereafter the birds received water from a hanging automatic bell drinker. The chickens were debeaked at the hatchery. All feed placed was recorded, as were body weights at three and six weeks of age. The birds were vaccinated by the incontact route at day 1 with A3 infectious bronchitis vaccine and by the same route with Vic S infectious bronchitis vaccine at 14 days of age. All dead birds were autopsied. 9 .Breeds and-Treatments 1600 commercial male broilers were obtained from each of two commercial hatcheries, Tegels and Steggles. *Department of Biochemistry and Nutrition, University of New England, Armidale, N.S.W. 2351. 314 There were four treatments (four replicates of each) per breed. 1q 2s 30 4 l Conventional commercial Protein concentrate plus Protein concentrate plus Protein concentrate plus diet wheat sorghum wheat and sorghum in separate feeders, Eqeriment 2 1600 sexed chickens were obtained from both Tegel and Hyline hatcheries. There were four treatments (four replicates of each) per breed. 1. 20 3 4 Diets The diets fed in Experiments 1 and 2 are presented in Table 1. The conventionally fed birds received a commercial type starter ration to 28 days of age, after which they received a commercial finisher ration. The choice fed birds received a protein concentrate in crumble form in one feeder and grain in the other two feeders. Crushed grain was fed for the first four days, after which the grain was supplied uncrushed. TABLE 1 Composition of diets fed in Experiment 1 .. l l Conventional commercial Protein concentrate plus male chickens Conventional commercial Protein concentrate plus female chickens. diet - male chickens wheat and sorghum in separate feeders diet - female chickens wheat and sorghum in separate feeders - In Experiment 1 the coccodiostat used was Amprolmix-plus, supplied at the curative level in the drinking water for 24 hours over seven days. In Experiment 2 Amprolmix-plus was included in the concentrate at three times the recommended level. Carcass Composition The fat content of the carcasses of the birds was determined at six weeks of age as previously described (Mastika, 1981). 315 RESULTS The results of Experiments 1 and 2 are presented in Tables 2 and 3 respectively. TABLE 2 Body weights, food conversion ratios and percentage carcass fat for Experiment 1 TABLE 3 Body weights, food conversion ratios and percentage carcass for for Experiment 2 DISCUSSION Growth overall was better in Experiment 1 which was conducted in the cooler spring months. In this trial the choice fed birds performed essentially as well as those fed complete diets. In Experiment 2, which was conducted in the summer, was lower overall and the choice fed birds did not reach as those on the complete diets. F.C.R. was generally not A possible explanation of this poorer performance may be the whole grains used in Experiment 2 had a large amount and dust in them. the the as the of growth rate same weights good either. fact that broken grains An interesting observation in both trials was that, when offered both grains, the broiler chickens consistently consumed more sorghum. Similar observations,have been made in laying bird trials. In a recently completed laying trial (Cumming, unpub) pullets were choice fed from seven to 84 weeks of age. They performed as well as birds fed a high quality complete laying diet. Pullets restricted fed on a time basis produced in the same manner as pullets restricted on a complete diet. 316 Overall these results suggest that choice feeding may have application -0 in the poultry industry. More research is required to establish the principles on what governs the intake of chickens and hens to enable this system of feeding to be propertly applied and evaluated. ACKNOWLEDGEMENTS The considerable help of Mr, John Swainston of Fielders Stock Feeds in producing the various rations is gratefully acknowledged. The . coccidiostat Amprolmix-plus was generously supplied by Merck, Sharpe & Dohme. The financial assistance of the Australian Chicken Meat Research Committee to help conduct the two broiler trials is gratefully acknowledged. REFERENCES MASTIKA,.M. (1981). M.Sc.Ag. thesis, University of New England. MASTIKA, M. and CUMMING, R.B. (1981a). Choice feeding of broiler chickens at high temperatures. In 'Recent Advances in Animal Nutrition in Australia 1981'. p. 228, ed. D.J. Farrell (University of New England Publishing Unit). MASTIKA, M. and CUMMING, R.B. (1981b). Proc. Fourth Australasian Poultry and Stock Feed Convention. p.79. Perth.