Purdue University
Agricultural Experiment Station
Lafayette, Indiana
Mimeo DH-65
April 17, 1957
FEEDING VALUE OF SILAGES FOR DAIRY CATTLE
C. H. Noller and N. S. Lundquist
Dairy Department
Although many experiments have been conducted to measure the feeding value of silages for dairy cattle, more information is needed on the comparative values of various silages. In most of the experiments, hay and grain were used in addition to the silages. Any differences occurring between the silages were probably obscured, to some extent at least, by the hay and grain in the ration.
The amount and quality of the forage consumed is important in feeding the milking cow. Although quality is difficult to determine, it is best measured by the amount consumed and production per unit of forage.
Forcing a cow to consume a product in the form of silage, which she normally would refuse as pasture, will reduce milk yield. This is often the case when poor silages are fed. A cow will produce more milk when consuming the tops or leafy portion of the plant than the stem portion. Therefore, in the making of grass silage for dairy cattle, one should harvest the plant at the most immature stage of growth which is agronomically and economically feasible. Grain should be used, if necessary, to supplement any deficiencies in quality.
Grass Silage
Quality grass silage is an excellent feed for dairy cattle if made from immature legumes and grasses, and properly ensiled to produce a quality product with the maximum retention of nutrients. If it meets all these criteria, it should be a palatable and nutritious feed. Cows fed grass silage as the sole feed can produce high levels of milk, provided the silage is of high enough quality. Results from Scotland indicate that Ayrshire cows would consume up to 150 pounds of grass silage as the sole feed. Experiments conducted by the Purdue Dairy Department also showed that cows would consume large quantities of grass silage, but this was dependent on the quality of the silage.
On one experiment, consumption differed markedly between three silages made from the same forage, but differing in the type of fermentation which occurred in the silo (Table 1).
TABLE 1. Daily dry matter consumption and milk production of cows fed grass silage as the sole feed.
  Silage	  Preservative	  Quality	  pH	Dry Matter Consumed per 100 lb./body wt.	 FCM Produced
	(per ton)			(lb.)	(lb.)
Alfalfa-Brome, macerated	8 lb. bisulfite	Fair +	4.45	2.38	23.3
Alfalfa-Brome, macerated	None	Poor	5.50	2.16	22.9
Alfalfa-Brome, chopped	8 lb. bisulfite	Good	4.45	2.49	25.4
Grass silage can be used as the sole roughage, although some people feel that some hay should be fed (4 to 5 pounds daily) to maximize intake and to satisfy the cow's appetite for dry feed. The hay would supply vitamin D which may be deficient in the grass silage, Depending on the dry matter content, 3.0 to 3.5 pounds of grass silage is equivalent to one pound of hay. In general, varied results have been obtained when comparisons were made between forages preserved as hay or as silage.