HIGH PROTEIN CONTENT OF PASTURE.

New Zealand Journal of Agriculture, Volume XXXVIII, Issue 2, 20 February 1929, Page 97

HIGH PROTEIN CONTENT OF PASTURE.

RESEARCH ON SUGGESTED RELATION TO DAIRY COW DISEASES.

B. C. Aston,

F.N.Z.Inst., Chief Chemist, Department of Agriculture.

Attention having been drawn to the possibility that a ration having a high protein content, such as that furnished by the richest New Zealand pastures, may have a considerable influence in contributing towards the incidence of reproductive troubles in cattle, the matter is now being investigated by the Department of Agriculture. Farmers are asked to assist those officers who are collecting samples for this purpose. .The evidence so far gathered shows that this is a line of investigation well worthy of thorough inquiry.

North Island soils are usually well provided with the valuable fertilizing-agent nitrogen, and this is reflected in the better pastures, where extraordinarily high figures for nitrogen, and consequently protein content, have been lately recorded in the lower Wairarapa, Waikato, and Nelson districts, the last by Mr. T. Rigg, of the Cawthron Institute. This would not warrant special mention of the matter if at the same time there were not appearing in New Zealand troubles in stock which may possibly be referred to an excess of nitrogenous constituents in the diet. Many years ago at Waitotara nitrates or nitrites in mangels were held responsible for the deaths of many cattle and pigs when fed on these roots growing in the field (this Journal, Vol. 3, page 311, 1911). This will show the high percentage of nitrates which may occur in New Zealand soils under favourable conditions. The pulpy kidney condition in lambs occurring in Central Otago and other districts has been associated with an excessive proportion of amines in the spring grass, and this has been suggested as a cause of the mortality {Journal, Vol. 34, page 231, 1927). , . ,

Bulletin 417 of the Ohio Agricultural Experiment Station comments on the fact that three experimental cows dieted on the “ narrow ” ration of 1-2 suffered from temporary sterility, became very thin, and seemed to tire of the ration. The authors say, Their response to this ration is especially interesting in the light of many complaints which have come to our attention regarding breeding difficulties that seem to attend the -use of high protein rations.” The ratio 1-2 of digestible protein to non-protein is what is called a very narrow one —that is, the protein is excessively high compared with the nonprotein ; but it is important to note that some New Zealand pastures provide even a narrower ration than this.

The suggested remedy for this state of things is to widen the ration by giving a -feed of much lower protein content,. supplementary to the pasture. What is at present required is more information, for the problem of temporary sterility is dairy ■ herds in one of immense importance. If herds which receive summer supplementary feed such as green oats, green maize, turnips, sugar-beet pulp, and maize or other starchy meals low in protein do not suffer, it warrants further inquiry. Woodman [Journal of Ag. Science, Vol. 6, page 25, 1926,. and Scot.

Journal Ag., Vol. II, page 383, 1928) appears to have suggested something similar, and if this is so where the protein content of pastures is not so high as in New Zealand, how much more necessary is it here. He says, “ It appears justifiable to assert that optimum results are not possible on closely grazed pasturage with any class of stock —■ young grazing stock, dairy cattle, and fattening animals alike—unless such animals are receiving, at all stages of the season, some supplementary food which is richer in carbohydrates.” He also suggests that carbohydrate supplements might materially mitigate evils, such as scouring in early spring, possibly due to excessive digestible protein.