Forage Quality and
By Muh.Salman Naeem & Muh. Shahbaz
quality is defined in many ways but is often poorly
Usually forage quality
receives less concern as it justify.
Adequate animal nutrition
is essential for high rates of gain,ample milk production,
efficient reproduction and maximum profits.
Pakistan has no normal
pasture appropriate for dairy sector, so dairy stocks,
mostly buffaloes, depends on cultivated annual forage for
A large number of
dairy stocks are kept in and around cities and feed have to
be brought in.
Most dairy animals are in and
around intensively cultivated and irrigated regions, except
for some rain-fed areas such as Rawalpindi, Attock and
There is no land for grazing,
so animals are kept at farmstead and stall-fed on cultivated
forage, crop residues and concentrates.
Pakistan has a total cropped area of 22.54 million hectare.
But only 2.35 million hectare area is under fodder crops.
Due to increased requirement, improved forage crops such as
multi-cut Oats, Rhodes grass, Berseem, Lucerne, Sorghum-
Sudan grass hybrids, Maize and Millet have been developed.
Analyzing forages for nutrient content can be used to
determine whether quality is adequate and to guide proper
ration supplementation. The vast irrigated tracts of the
Punjab, the North West Frontier Province and Sindh, which
are the major source of forage for urban dairies, are at low
altitude with a sub-tropical monsoon climate and hot
Cash crops such as wheat, sugar cane, maize, rice, and
forage crops like sorghum, Rhodes grass, alfalfa, clover,
and oats are commonly supply the grain and forage
requirements for urban dairies.
Due to suitable temperatures and availability of irrigation,
green forage is produced year the round. Improved forage
varieties and technology have been slow to reach the small
scale farms which account for the bulk of forage production.
Palatability: Animals select one type of forage over
another forage type on the basis of smell, feel and taste.
palatability may therefore be influenced by texture,
leafiness, fertilization, crop fall, dung or urine patched
in field, moisture content, pest problem, fungal infestation
and compounds present in it to taste sweet, sour or salty.
High quality forages are generally highly palatable.
Intake: Animals must consume adequate quantities of
forage to perform well. Typically, higher the palatability
and forage quality, higher the intake.
Digestibility: The extent to which forage is absorbed
as it passes through an animal’s digestive track varies
greatly. Immature, leafy plant tissues may be 80% to 90%
digested, while less than 50% of mature stem material is
digested. Approximately 0.5% digestibility goes down within
a day after crop maturity.
Nutrient content: Living forage plants usually
contain 70 to 90% water. To standardize analyses, forage
yield and nutrient content are usually expressed on a dry
matter (DM) basis.
Forage dry matter can be divided into two main categories:
(1) cell contents (the non-structural parts of the plant
tissue such as protein, sugar and starch); and (2)
structural components of the cell wall (hemicelluloses and
lignin). Rhodes grass has more DM% on equal age rather than
barseem and alfalfa.
Anti-quality factors: Various compounds may be
present in forage that can lower animal performance, cause
sickness, or even result in death. Such compounds include
tannins, nitrates, alkaloids, cyanoglycosides, estrogens,
The presence or their severity of these elements depends on
the plant species present, time of year, environmental
conditions, and animal sensitivity. High-quality forages not
contain harmful levels of anti-quality components.
■ Animal performance is the ultimate test of forage
quality, especially when forages are fed alone and free
choice. Forage quality encompasses “nutritive value” (the
potential for supplying nutrients, i.e., digestibility and
nutrient content), how much animals will consume, and any
anti-quality factors present.
Animal performance can be influenced by any of several
factors associated with either the plants or the animals.
Failure to give proper consideration to any of these factors
may reduce an animal’s performance level, which in turn
reduces potential income.
Factors affecting forage
Many factors influence forage quality. The most important
are forage species, stage of maturity at harvest, and (for
stored forages) harvesting and storage methods. Secondary
factors include soil fertility and fertilization,
temperatures during forage growth, and variety.
Legumes vs. grasses:
Legumes generally produce higher quality forage than
grasses. This is because legumes usually have less fiber and
favor higher intake than grasses. One of the most
significant benefits of growing legumes with grasses is
improvement of forage quality. But production may affect
intercropping due to different dormant season of crops.
warm-season grasses: There is considerable variation in
forage quality among the grasses used as cultivated forages.
Forage grasses are divided into two broad categories: cool
season and warm season. Cool-season grasses include
perennial and annual ryegrass. Rhodes grass is example of
Cool-season species are
generally higher in quality than warm-season grasses. The
digestibility of cool season grass species averages about 9%
higher than warm-season grasses. Minimum crude protein
levels found in warm-season grasses are also lower than
those found in cool-season grasses.
Within each category, annual
grasses are often higher in quality than perennials. Due to
differences in leaf anatomy, warm-season grasses convert
sunlight into forage more efficiently than cool-season
grasses, but their leaves contain a higher proportion of
highly lignified, less digestible tissues.
On that basis alfalfa
considered best by dairy specialist than Rhodes grass.
However, Rhodes grass is many time better as economical and
management point of view than Mott grass and alfalfa.
grown at high temperatures generally produce lower quality
forage than plants grown under cooler temperatures, and
cool-season species grow most during the cooler months of
the year. However, forage of any species tends to be lower
in quality if produced in a warm region rather than a cool
For example, in one study
annual ryegrass grown at temperatures of 18°C to 24°C
produced forage made up of 59% leaf material, but only 36%
leaf matter when grown at 32° C to 45°C.
Maturity stage at harvest is the most important factor
determining forage quality. Forage quality declines with
advancing maturity. For example, cool season grasses often
have dry matter (DM) digestibility’s above 80% during the
first 2 to 3 weeks after growth initiation in spring.
declines by 1⁄3to 1⁄2percentage units per day until it
reaches a level below 50%. Maturity at harvest also
influences forage consumption by animals. As plants mature
and become more fibrous, forage intake drops dramatically.
Intake potential decrease and NDF concentration increases as
plants age increase.
This is because NDF is more
difficult to digest than the non-fiber components of forage.
Also, the rate at which fiber is digested slows as plants
mature. Therefore, digestion slows dramatically as forage
becomes more mature. As I mentioned before nearly 0.5%
digestibility loses by fodder after maturity due to late of
Reduced leaf-to-stem ratio is a major cause of the decline
in forage quality with maturity, and also the loss in
quality that occurs under adverse hay curing conditions.
Leaves are higher in quality than stems, and the proportion
of leaves in forage declines as the plant matures.
The oldest portion of alfalfa
stems had less than 10% CP compared with 24% in alfalfa
leaves. Stem had much higher fiber levels than leaves, but
the older, lower alfalfa leaves were similar in quality to
the upper, younger leaves. However, older alfalfa stem
tissue was considerably lower in quality than young stem
tissue. Reproductive growth lowers leaf-to-stem ratio, and
thus forage quality.
Most cool-season grasses
require a period of cool temperatures (vernalization) for
flowering, so they produce reproductive stems only in the
spring. Thus, the forage quality of re growth of these
grasses is greater and changes less over time because they
have higher leaf-to-stem ratios than first-growth forage.
Legumes and some grasses such
as Bermuda grass can flower several times each season, so
their forage quality patterns are less closely linked to
Grass–legume mixtures: Grass–legume mixtures
generally have higher crude protein concentration and lower
fiber concentration than pure grass stands.
Fertilization of grasses with nitrogen (N) often
substantially increases yield and also generally increases
CP levels in the forage.
Fertilization with phosphorus
(P), potassium (K), or other nutrients that increase yield
may actually slightly reduce forage quality when growth is
rapid. Excessive levels of some elements such as potassium
may in some cases decrease the availability of other
elements such as magnesium (Mg) in the diet.
Daily fluctuations in
forage quality: changes in soluble carbohydrate levels
in alfalfa were linked to time of day. Plants accumulate
soluble carbohydrates during daylight and then use them
overnight. Thus, soluble sugars are lowest in the morning
and highest after a day of bright sunshine.
Alfalfa is harvested in the
late afternoon rather than in the morning. It appears that
the advantage of afternoon harvest is greatest on cool,
sunny days and when the forage is highly conditioned to
increase drying rates and minimize respiration in the
However, afternoon harvests
may not be advisable in high rainfall areas where every hour
of good drying time is needed in curing hay. In summer
season, digestibility may also be on lower endin case of
cutting at afternoon both in alfalfa and legumes.
Harvesting and storage
effects: Leaf shatter, plant respiration, and leaching
by rainfall during field drying of hay can significantly
reduce forage quality, particularly with legumes. Moderate
rain damage reduced alfalfa CP levels slightly and
digestibility dramatically, but NDF and ADF levels increased
Red clover hay quality was
also greatly reduced by rain, even though crude protein
increased. The total amount of crude protein did not
increase; the percentage of crude protein in the remaining
dry matter was higher due to leaching of highly soluble
constituents. Rainfall during curing damages legume leaves
For alfalfa hay exposed to
both drying and leaching losses, more than 60% of the total
losses of dry matter, CP, ash, and digestible DM were
associated with the leaves.
Rain during field drying has
less impact on the forage quality of grasses than legumes.
In one study, alfalfa hay that received rain was 12
percentage units less digestible than fresh forage, compared
with a difference of only 6 percentage units for grass hay
produced under similar conditions.
Damage from rain increases as
forage becomes dryer, and is especially severe when rain
occurs after it is ready to bale. Quality losses also occur
due to weathering, plant respiration, and microbial activity
during storage. In high rainfall areas, losses can be large
for round bales stored outside, due to weathering of the