Increased Profit from Pasture Management

                

Pasture management emphasizes utilization of all feed grown

Productivity of livestock as individuals and productivity on a per unit area basis both originate from the combined effects of (i) efficient capture of solar energy (sunlight), (ii) efficiency in forage harvested by the animal(s), and (iii) efficiency in conversion of the forage into animal growth or production. Feed grown does not become profit until it is utilized by grazing animals.

Sufficiently high stocking rates are necessary to graze the whole area of a paddock.

Poor utilization results in selective over grazing of the most palatable species, wasted feed, poor regrowth, and opening up of the sward with establishment of weeds.  Continuous heavy grazing may cause a reduction in legumes because of reduced energy reserves for regrowth.  High producing pasture species, on productive soils, have highest production with rotational grazing that allows a resting period for forage growth, and full recovery of reserves for regrowth.  When growth is slower, the recovery period between grazings is lengthened. 

 

The length of the rest period between grazings must be varied.

The rest period may be only 12-15 days after grazing in mid-April, but should be lengthened to 30-36 days after grazing in late August (Table 1).  To be able to manage pastures and to provide animal-free rest periods there must a sufficient number of paddocks.  This is illustrated in Table 2 with the number of paddocks required at the season¨s end.  Earlier in the season when rest periods are shorter fewer paddocks would be needed to complete one rotation of grazing.  Surplus forage from paddocks not included in this first grazing may be harvested as haylage or hay, thus conserving   feed   for  winter.  Too often dairy farmers in New England adopt a modified version of set stocking or lax form of rotational grazing.  With set stocking there is difficulty in matching feed supply to animal requirements and as a consequence many farmers under- stock continuously grazed areas. 

Productivity of pastures will also be influenced by the availability of soil nitrogen. This most economically can be provided by legumes fixing atmospheric nitrogen in root nodules.  Fertility and grazing management must be designed to promote the growth and persistence of legumes in mixed grass and legume pastures.

Table 1. Length of Rest Period.

 Mid-Apr to mid-May 12-15 days

June 1                   24
July 1         
           24
August 1               30
September 1       30-36

 

Table 2.  Number of paddocks needed for a 36 day rest period.

   Days             Number of
   Grazing     Paddocks

   ½                   73
   1                    37
   2                    19
   3                    13
 

 

 

Correct height of grazing of varies with species (Table 3).

  Table 3.  Guide for managing forage species and mixtures.

 

                                                                                                            Rotational grazing
                                                         Continuous grazing                         heights      
Species                                             average height of pasture       Before          After   

                                                                       -------------- inches or stage ---------------

  Bluegrass-white clover                                 2.0 to 3                       4 to 6          1 to 2

  Orchardgrass-ladino clover                          3.5 to 5                      7 to 10         2 to 4

  Alfalfa                                                             N/R1                          bud2           2 to 3

  Alfalfa-grass                                                  N/R                            bud             3 to 4

  Red clover                                                     N/R                            bud             2 to 3

  Red clover-grass                                           N/R                           bud             2 to 4

  Birdsfoot trefoil                                              3.5 to 5                      bud3           3 to 4

  Birdsfoot trefoil-grass                                   3.5 to 5                      10 to 12      3 to 4 

 

  1 N/R - not recommended to graze continuously

  2 Allow alfalfa to go to first flower at least once during the summer

  3 To replenish the stand, allow trefoil to go to seed once every two years

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Continually grazing tall growing species such as orchardgrass to one inch will depress yield and cause a decline in plant vigor because of low residual leaf area and because tillers that store energy for regrowth are also partially grazed.  Such management of alfalfa, which depends on the root reserves forregrowth, would soon lead to a stand decline, both in vigor and number of plants.  Shorter growing species such as white clover, Kentucky bluegrass and perennial ryegrass can withstand grazing to one inch.  For legume-grass mixtures, light grazing over a prolonged period may lead to a reduction in legumes because of competitive growth of the grass.  Continuous heavy grazing may cause a reduction in energy reserves for regrowth.  Rotational grazing, with a short grazing period followed by  adequate regrowth between grazings, will promote persistence of legumes, and increase growth and quality of grasses.  It may also increase profitability of the farm enterprise.

 

Stephen Herbert

Dept. of  Plant and Soil Sciences

University of Massachusetts Amherst

Crops, Dairy, Livestock News. Volume 1:1, Mar. 1996

 




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