Milk composition in the United Kingdom / report of an Interdepartmental Committee.
- Great Britain. Interdepartmental Committee to Consider the Composition of Milk Sold off Farms in the United Kingdom.
- Date:
- [1960]
Licence: Public Domain Mark
Credit: Milk composition in the United Kingdom / report of an Interdepartmental Committee. Source: Wellcome Collection.
69/100 page 63
![Grazing 64. Published work suggests that, provided an adequate quantity of grazing of good quality is available, milk of satisfactory composition can be produced from grazing alone over the whole grazing season and that, in such circumstances, the provision of supplementary feeding in the form of concentrates gives no worthwhile improvement in s.n.f. or in milk yield. Where, due to poor management, drought or excessive rainfall pasture yield and quality decline severely in the later summer months, additional feeding may, however, become essential. 65. The main factor affecting the quality of grazing is the stage of growth of the grass. Very short, succulent spring grass with a high energy, low fibre content often produces milk with a low fat and high protein con- tent ; somewhat longer but still leafy grass generally produces milk of normal composition, whereas more fibrous, stemmy grass tends to lower both milk yield and s.n.f. by restricting the feed intake of the cow. 66. From the available results we do not consider that the application of artificial fertilisers at rates normally used in good husbandry is likely to affect milk composition. Similarly, although there are differences in chemical composition between the various species of grass commonly used in the United Kingdom, we believe that any effect this may have on milk composi- tion is small and is liable to be overriden by the effect of stage of growth of the pasture and the quantity available. 67. It has been suggested that spring grazing may possess special consti- tuents which may affect milk composition. While this cannot entirely be dismissed, it seems more likely from published information we have con- sidered that the higher s.n.f. contents commonly observed are due more to increases in quantity and quality of the food consumed when cattle change to spring grazing after a winter ration which may often have been at a fairly low level. Winter feeding of grass products 68. Of the grass products used in winter feeding, hay appears in the majority of diets, silage in some 20 to 30 per cent. (rather less in Northern Ireland) and dried grass in only a small proportion. Hay is very variable in quality, depending on the stage of growth at which it is cut, its botanical composition and the effectiveness of the haymaking process. In consequence hays range in their content of starch equivalent from 20 to 45 (per 100 Ib. of dry matter). Since hay often accounts for half the total bulk of the cow’s ration (as dry matter), its quality can profoundly affect milk composition. Indeed, as was the case in the winter of 1958/9, a bad hay harvest is generally followed by low winter s.n.f. contents. 69. Silage, like hay, varies greatly in starch equivalent (35 to 60 calcu- lated on a dry matter basis) but, in addition, the dry matter content commonly varies between 15 and 30 per cent. From these extremes it can be noted that 100 lb. of good silage might supply at least twice as much starch equivalent as the same quantity of a poorer product. Moreover, it is known that, in general, the ensilage of wetter materia] results in poorer fermentation and in a less palatable product.](https://iiif.wellcomecollection.org/image/b32177483_0069.jp2/full/800%2C/0/default.jpg)
