Grazing stubble fields


Cows have different supplementation needs when turned out on stubble fields in the fall.

Cows will pick and choose what they eat from the straw, chaff, throw over grain, weed

seeds in the stubble, slough hay from the low areas and mature hay growing along the

fences and headlands. The quality depends on what they eat, the type of crop grown,

fertility program and stage of maturity when the crop was cut or harvested. How the

combine was set will impact how much light grain and weed seeds were thrown out onto

the ground.


Straw, chaff and over-mature grass hays are typically low in protein, energy, calcium

and magnesium. These feeds are also high in neutral detergent fibre, which can reduce

total feed intake, and relatively high in phosphorus. Grains and weed seeds are also

high in phosphorus and have higher energy and protein content than the grasses, straw

and chaff.


Most of these feeds are low in calcium and magnesium. A diet that is low in calcium

and higher in phosphorus can reduce phosphorus absorption. This is important because

phosphorus is the driver of all metabolic functions. When it is not absorbed, feed intake

is reduced. That in turn reduces milk production and weight gain on the calves. Cows

can also start to lose weight. A continuous imbalance can impair reproductive

performance, with cows taking longer to cycle and conceive a calf next year.


It is not common this time of year, but a calcium or magnesium deficiency can cause

cows to go down, and it generally requires a veterinarian to treat animals in this

situation.


A mineral supplementation program should contain additional calcium and magnesium,

but a 2:1 mineral does not provide enough calcium to remedy the situation. A feedlot

mineral with a 3:1 or 4:1 calcium to phosphorus ratio is preferred.


If there is a 1:1 mineral is left over from the summer, mix 1 bag of limestone - 38%

calcium - with 1 bag of mineral and 1 bag of fortified trace mineral salt - with selenium.

One hundred cow-calf pairs should consume this mixture, weighing roughly 165 lbs. in 5

to 6 days. If consumption is too low, add 8 to 10 lbs. of dried molasses to the entire mix

and adjust the amount of molasses to get the proper intake. If a 2:1 mineral is available,

reduce the limestone to 20 pounds per mix.


Feeds that are over-mature or crop aftermath are usually low in protein. A lactating cow

needs a minimum on a dry basis 11% protein to maintain feed intake and milk

production. Dry cows can manage on 8 to 9% protein.


Using tubs or block to supplement protein will help solve the problem. Calcium and

phosphorus levels are typically low in this type of product. Concerns with a free choice

tub or block are over or under consumption and the cost. Other options include feeding

3 to 4 pounds of grain every third day along with a protein supplement or wean the

calves and put dry cows onto these fields (this reduces protein requirements).


Creep feeding the calves with a ration that is between 14 and 16% protein will improve

average daily gains. If feeding straight oats, which has 10 to 11% protein on average,

the calves will put down fat rather than lean growth. They may not frame out properly,

resulting in an animal that may be discounted at auction. A mixture of 1/3 peas and 2/3

oats or barley by weight will provide a creep ration that meets protein and energy

requirements. With lower grain prices and high calf prices creep feeding will pay very

well in the long run. Creep feeding also reduces the stress on the calves when they are

weaned. They know what grain is and they have less problems adjusting to the new

ration compared to calves that have not received creep feed.