VALUE AND USE
SPECIES: Amaranthus retroflexus | Rough Pigweed 



WOOD PRODUCTS VALUE : 
NO-ENTRY


IMPORTANCE TO LIVESTOCK AND WILDLIFE : 
Rough pigweed affects the kidneys of swine and cattle when animals
consume large quantities of fresh material for 5 to 10 days.  Cattle
have developed perirenal edema and toxic nephrosis after ingesting rough
pigweed.  The toxicant has not been identified, although oxalates and/or
phenolics have been suspected [37].  Additionally, rough pigweed
accumulates nitrates, which causes poisoning in most livestock species
when ingested in large quantities either fresh or in hay [6,21,44].  The
excess nitrates cause cattle to bloat [41].  In the Midwest, pigs have
been poisoned by rough pigweed growing under drought stress.  In drought
conditions, rough pigweed accumulation of nitrates accelerates [28,49].

In Nebraska, cattle consumed immature leaves and tops of rough pigweed
in fields seeded to big bluestem (Andropogon gerardii var. gerardii).
By mid-July of the first year of the study, nitrate concentration had
reached toxic levels (10,000 ppm).  In the second year, nitrate levels
exceeded the toxic level at the beginning of the grazing season [23].

Sheep in Texas were maintained for varying lengths of time on rough
pigweed pasture supplemented with wheat and alfalfa hays [15].

Scaled quail in Texas made use of rough pigweed seeds.  When available,
seeds averaged 0.9 percent of food eaten.  In the highest recorded use,
rough pigweed seeds made up 3.6 percent of food eaten.  Percent use was
greater than rough pigweed presence [1].


PALATABILITY : 
Rough pigweed is probably unpalatable when mature because of the stiff,
spine-like bracts in the flower clusters.

In Utah, rough pigweed was rated as having fair palatability for cattle
and horses, and good palatability for sheep [7].

In Minnesota, rough pigweed was as palatable to sheep as oats (Avena
sativa) [25].


NUTRITIONAL VALUE : 
Rough pigweed seeds with hulls contain 18.0 percent protein [29].

The nutritional components of immature rough pigweed browse are [29]:

                  Component       Percent

                Ash                18.8
                Crude Fiber        10.8
                N-free Extract     43.2
                Protein            25.7


The use that various animals can make of protein in rough pigweed browse
is [29]:
                             
                                  Percent
                  Animal     Digestible Protein 
      
                  Cattle           19.7  
                  Goats            20.5
                  Horses           19.3
                  Rabbits          18.5
                  Sheep            20.9

The food value of rough pigweed for wildlife species in several western
states is rated as follows [7]:

                              North                   
                              Dakota        Utah       Wyoming

        Pronghorn              good         fair        poor
        Elk                                 fair        poor
        Mule deer              good         good        poor
        White-tailed deer      good                     poor
        Small Mammals                       fair        good
        Small nongame birds                 good        good
        Upland game birds      good         fair        good
        Waterfowl              good         poor        fair

In Minnesota, rough pigweed harvested from late June to mid-July showed
a nutrient composition and digestibility for sheep equivalent to that of
high-quality alfalfa (Medicago sativa).  Rough pigweed contained
adequate minerals to meet the requirements of ruminants.  However, it
must be utilized at relatively early stages of maturity.  Nitrate
concentration, which has been implicated in livestock poisoning, is
highest in rough pigweed just before bloom.  Calcium to potassium ratio
in rough pigweed is such that it should not be fed as the sole ration
[25].


COVER VALUE : 
The degree to which rough pigweed provides environmental cover for
wildlife species in several western states is as follows [7]:

                        North
                        Dakota          Utah         Wyoming

Pronghorn                good           poor          poor
Elk                                     poor          poor
Mule deer                good           poor          poor
White-tailed deer        good                         poor
Small mammals                           fair          fair
Small nongame birds                     fair          fair
Upland game birds        poor           poor          poor
Waterfowl                fair           poor          poor


VALUE FOR REHABILITATION OF DISTURBED SITES : 
NO-ENTRY


OTHER USES AND VALUES : 
Young leaves of rough pigweed are used as salad greens when the plant is
only a few inches tall, before the stem becomes woody.  Fresh young
plants can also be used as a potherb.  Seeds are edible whole or ground
into meal.  However, because rough pigweed concentrates nitrates, it
should be used in moderation, particularly when taken from
nitrate-fertilized areas [9].


MANAGEMENT CONSIDERATIONS : 
Rough pigweed is a useful component of patchwork vegetation for scaled
quail habitat, providing both food and cover [1].

Rough pigweed is difficult to eradicate when once established [34].  A
survey of weeds in spring annual crops throughout Manitoba over a 4-year
period showed 83 weed species.  Rough pigweed was the third most common
dicotyledonous weed [40].  In Kansas, it was the most abundant forb weed
in the seedbank [24].

Rough pigweed can be controlled with herbicides [30].

Cultivation reduces longevity of rough pigweed seed, apparently by
increasing soil aeration, exposing the seeds to light, and generally
improving conditions for germination.  High soil temperatures favor
germination and reduce rough pigweed seed survival [8].

Rough pigweed showed no establishment in intact prairie vegetation in an
Illinois study.  It did, however, establish in gaps in prairie
vegetation.  Flowering and seed set increased with increasing gap size
[26].

An investigation was conducted in Nebraska as to the effect of cattle
grazing in controlling rough pigweed and other weeds in seeded
grassland.  Cattle consumed immature rough pigweed, but nitrate
accumulation limited grazing rough pigweed as a weed control practice
[23].

Related categories for Species: Amaranthus retroflexus | Rough Pigweed