Question #5 You have a 320 acre pasture that is stocked with 26 mature cows (1,1
ID: 3195142 • Letter: Q
Question
Question #5
You have a 320 acre pasture that is stocked with 26 mature cows (1,150 lbs.) from May 15 to October 1. The cows have calves (0.3 AUE) with an average calving date of April 1 The pasture produces about 1,500 lbs./acre of air-dry forage. What is the (a) stocking rate, (b) stocking density of cows, (c) cumulative grazing pressure, and (d) cumulative forage allowance?
You have a 320 acre pasture that is stocked with 26 mature cows (1,150 lbs.) from May 15 to October 1. The cows have calves (0.3 AUE) with an average calving date of April 1 The pasture produces about 1,500 lbs./acre of air-dry forage. What is the (a) stocking rate, (b) stocking density of cows, (c) cumulative grazing pressure, and (d) cumulative forage allowance? 5.Explanation / Answer
One animal unit is defined as a 1000 lb cow with or without a nursing calf, with a daily dry matter forage requirement of 26 lb.
It says in the question that the cows have calves with a calving date of April 1st which ensures the calves are no older than 6 months old by October 1st. This enables us to follow this definition that 1 AU = 1 Cow + (calf until 6 months old) or 1 AU = 1 Cow + no calf.
a) Stocking rate needs to be expressed in Animal Unit Months per unit area.
There are 26 1,150 lbs cows that lead to 26 1.15 Animal units of cows.
May 15 to October 1 means that the number of months are 4.5 months in the pasture.
So AUM = animal unit months = 26 x 1.15 AU x 4.5 months = 134.55 AMU.
No. of acres = 320 Acres.
------> Stocking Rate = AMU/ac = 134.55/320 = 0.42 AMU/ac.
b) There's no mention of seperate paddocks in the question. This leads us to assume that every acre is being consumed 100% of the time with the cows continuously and evenly grazing the pasture at all times.
So, in this case, stocking density = stocking rate = 0.42 AMU/ac.
c) Cumulative grazing pressure is defined as the demand/supply ratio of cumulative or total forage requirements of the livestock to total availabe forage in the pasture at the time.
In our case, the demand can be obtained from the weight of the cows.
i.e Demand for forage = 26 x 1150lbs = 29,900 lbs
Supply for forage = 1500lbs/acre x 320 acres = 480,000 lbs
Cumulative Grazing Pressure = 29,900/480,000 = 0.0623
d) Forage allowance is defined as the amount of forage available to an animal, calculated by weight over weight.
In our case, the total cattle weight = 26 x 11,50lbs = 29,900 lbs
And the amount of forage available = 1,500lbs/acre x 320 acres = 480,000 lbs
Hence, the forage allowance is 480,000/29,900 = 16.05.
This is read as the forage allowance is 16.05 pounds of forage availabe for every one animal pound.
Cheers!