One of the trickiest parts of
raising animals on pasture is trying to minimize your dependence on
purchased feed.  Granted, with non-ruminants like chickens and
pigs, a traditional pasture of grasses and legumes can only provide a
portion of the animals’ diets, but I still enjoyed Small-Scale
Livestock Farming‘s
explanation of how to maximize the value of your pasture by
understanding the biology of both pasture and animal.



The first factor to
understand is that working animals need more food at certain times of
the year.  Maintenance rations are the baseline for an animal who
is all grown up and not producing eggs or milk.  Farmers need to
add supplemental nutrition on top of the maintenance ration when
animals are expending extra energy growing, nursing, or laying. 
For livestock other than pigs and poultry, the maintenance ration can
usually be hay and/or grass, but the supplemental feed is usually grain
for all of the above unless you time your grazing year very carefully.



If you’re careful, you plan
your annual cycle so your livestock only need maintenance rations when
the grass is growing slowly, then they can enjoy excess forage when
they need supplemental rations.  Making a diagram like the one
shown here is a fun way of working out your annual schedule.  I
was planning three rounds of broilers, trying to make their feed needs
(red shapes) fit on top of the peak pasture growth (green blob). 
(As a side note, my current schedule matches this chart pretty well,
except that I raise our last round of broilers later than the chart
depicts so my chickens can eat up excess garden scraps, which peak in
late summer and early fall.)



Another factor to
consider is how high quality that pasture is, meaning
how much energy your animals get from every bite.  You’d think
that an
animal could just eat twice as much woody grass to meet their
nutritional needs, but the excess fiber slows down digestion, so
there’s usually not room in an animal’s stomach for additional
low-quality forage.  The result is that the animal actually eats
less pasture when quality is low,
and you’re forced to fill the slack with grain or other purchased feeds.

Time of year makes a big
difference in forage quality (with the first spring flush being the highest
quality), but so does species.  In the past, I’ve considered
growing warm season grasses to fill in the midsummer slump, but
Ekarius’s book explained why our
chickens ignored the warm season grasses we do have — warm season grasses
produce a thickened sheath to prevent drying out in
hot weather, which results in a higher fiber content in most cases, and
chickens can’t handle lots of fiber.  In contrast, cool season
grasses seem to lead the way in providing the most calories per pound
of leaves, while legumes (of course) are highest in protein.  The
table below sums up nutritional information for many of the common
pasture grasses and legumes:

I know that was a lot of
in-depth information, but hopefully it’ll help you tweak your pasture
cycle to get the most out of the grass you have.  Good luck!