Forage

Grass

Characteristics

Typically based on ryegrass, but often mixed swards with cocksfoot, fescues, timothy, and legumes (e.g. clover). It is present in rough/hill grazing (often with heather, rushes, mosses), permanent pasture and rotational leys, the latter often high yielding italian or perennial ryegrass monocultures.

	DM (%)	ME (MJ/kg DM)	CP (g/kg DM)
Grass (young)	15 - 20	11.5 - 12.5	150 - 250
Grass (mature)	25 - 50	9.5 - 10.5	50 - 130

Associated Problems

Scours, hypomagnesaemic tetany (especially in winter, or in rapidly growing grass (e.g. spring,/early summer, late summer/autumn), bloat (especially as mixed legume swards), pasture-induced laminitis.

Silage and Haylage

Characteristics

Silage is a fermented crop with a low dry matter content. It is cut at a relatively early stage of development and stored under anaerobic conditions (clamp or big bale). Haylage is similar to silage but is often cut at a more mature stage and is typically baled. Haylage has a higher pH and DM than silage and can often be of more variable quality. With horses haylage is typically preferred (by owners) to silage.

	DM (%)	ME (MJ/kg DM)	CP (g/kg DM)	pH
Silage	15 - 20 (20-30 clamp)(40-50 bale)	9.5 - 12	120 - 190	3.8 - 4.8
Haylage	50-60	9 - 11.5	75 - 110	4.5 - 5.5

4.8) or too acidic (pH < 3.8).

Hay

Characteristics

Hay is dried grass, either naturally or artificially (dependent on the weather). It is cut at a relatively late stage of maturity and is typically of variable quality in colour and smell, and nutritive value. There are various types of hay such as ryegrass, meadow, and timothy.

	DM (%)	ME (MJ/kg DM)	CP (g/kg DM)

Hay 80 - 90 7.5 - 10.5 50 - 150

Associated Problems

Moulds/mycotoxins.

Straw

Characteristics

Straw (usually barley or oat for feed) can be treated with alkali, urea or ammonia. It is commonly used as a roughage source for growing ruminants, and especially animals being reared in cereal beef systems.

	DM (%)	ME (MJ/kg DM)	CP (g/kg DM)

Straw 86 - 88 6.1 - 7 34 - 38 Straw (ammoniated) 84 - 88 7.4 - 7.8 68 - 75

Associated Problems

Moulds/mycotoxin. Impaction within GI tract (especially horses). High intakes of straw (+ grains) are associated with hypomagnesaemic tetany (due to high K levels in grain and straw)

Whole-Crop Cereal Silage

Characteristics

Maize whole-crop silage has high energy concentration while having a low protein concentration. It is harvested when grain is in the late dough stage. Barley, oats, wheat, and triticale are also used for whole-crop cereal silage either as monocultures or mixed with legumes (e.g. peas) to improve protein content. They are also high in energy while low in protein. Whole-crop cereal silages are fed as sole forage or mixed with grass silage.

	DM (%)	ME (MJ/kg DM)	CP (g/kg DM)

Maize whole-crop silage 22 - 35 10.5 - 12 65 - 110 Barley whole-crop silage 30 - 40 9 - 11 80 - 110

Associated Problems

Clostridia. Listeriosis. Acidosis. Poor fermentation (pH > 4.8) or too acidic (pH < 3.8).