44 Station Bulletin 372 



To date, in those rations where choline has not been supplied, a serious 

 loss of weight has occurred. Production was less seriously affected, but has 

 been 6 per cent below the control which averaged 60 per cent. In the ration 

 in which additional choline, methionine and crystine were supplied, produc- 

 tion has averaged 70 per cent and weight maintenance has been as satisfac- 

 tory as in the control group. 



R. C. RiNGROSE, H. A. Davis 



Utilization of Sulphite Yeast as a Feedstuff for Poultry 



Yeast for feeding purposes can now be made from the sulphite waste 

 liquor from pulp and paper mills. The product contains about 50 per cent 

 of protein and is a rich source of many vitamins required by poultry. Dur- 

 ing the year, a sufficient quantity of sulphite yeast was available for feeding 

 experiments with chicks and laying hens. When used as the only protein 

 supplement for chicks, sulphite yeast was approximately 20 per cent less effi- 

 cient than soybean oil meal. The explanation for this appears to lie in the 

 fact that, on the basis of present information, sulphite yeast contains about 

 20 per cent of non-protein nitrogen. Thus, when compared on an equivalent 

 protein basis, sulphite yeast is less satisfactory for promoting growth. When 

 4 per cent of fish meal was added to the soybean oil meal and the sulphite 

 yeast rations, growth on the latter was markedly improved but was still about 

 20 per cent less than on the soybean and fish meal ration. 



When equal parts of the protein supplement necessary in the ration 

 were supplied from sulphite yeast and soybean meal, growth was markedly 

 improved over that on yeast alone. The combination was slightly better 

 than the combination of yeast and fish meal although the difference was not 

 statistically significant. Addition of 4 per cent of fish meal to the soybean- 

 yeast combination resulted in further improvement in growth. Results on 

 this ration with respect to growth, feed efficiency, and mortality were equal 

 in all respects to the results obtained on the ration of soybean oil meal and 

 fish meal. 



The use of additional choline may be of importance in the utilization of 

 the soybean-yeast protein combination. The results from one pen in which 

 .25 per cent of choline chloride was added to the soybean-yeast protein com- 

 bination without fish meal were intermediate between the growth results ob- 

 tained with the soybean-yeast combination alone or when supplemented with 

 4 per cent of fish meal. 



The availability and utilization of riboflavin and pantothenic acid from 

 sulphite yeast by chicks have been studied. From the results obtained it is 

 concluded that this product is a satisfactory source of these vitamins for the 

 chick. Since the yeast was assayed for vitamin content by microbiological 

 procedure, it is concluded that such assays are reliable for estimating ribo- 

 flavin and pantothenic acid content in this product for poultry-feeding pur- 

 poses. 



Experiments with sulphite yeast for laying hens producing hatching eggs 

 have also been carried out. Under the conditions of the experiments sulphite 

 yeast was a satisfactory protein supplement for hens producing hatching 

 eggs. With sulphite yeast as the only protein supplement production re- 

 sults, feed consumption, body weight maintenance, mortality, hatchability of 



