The Effect of Feeding Cottonseed Meal as the only Concentrate on Several Properties of Milk. II. Nitrogen Distribution

Abstract

Summary The nitrogen distribution of the milk produced by a group of cows receiving cottonseed meal as the only concentrate was compared with that of milk from a comparable group receiving a concentrate mixture of corn gluten meal, wheat bran, and ground corn and oats. The roughage was the same for the two groups. The milk from the cottonseed meal group had a higher non-protein nitrogen content than that from the control group. The two systems of feeding resulted in no apparent differences in the non-casein protein nitrogen content of the milk. About four months after placing the cows on their respective experimental rations, the group receiving cottonseed meal as the only concentrate began to produce milk of a lower casein nitrogen content than did the control group. The comparatively lower casein nitrogen was accompanied by a lower fat and total solids content in such a ratio that the casein nitrogen expressed as per cent of total solids was the same for both groups. Differences in the total nitrogen content of the two milks were dependent on the relative levels of non-protein and casein nitrogen; hence the total nitrogen was first higher and then lower in the milk from the cottonseed meal group than in the control group. The quantity of milk produced by the two groups of cows was essentially the same; therefore the differences in properties of the milk reported in this series of articles cannot be related to the milk yields.