The freestall divider has a number of functions, including:
- Defining the lateral limits of the resting space
- Facilitating the lying direction of the cow – straight rather than diagonal
- Permitting or preventing side lunge
- Determining the height of the neck rail
Obviously, it is preferable if the divider performs these functions without injuring the cow. In this section, we will assume that we are going to provide the cow with the necessary space to rest comfortably using the latest recommendations for stall length and width, and refer to dimensions suitable for a 1400 to 1600-lb (640 to 730 kg) typical Holstein cow. We will also mount the dividers to avoid obstructions in the lunge space in front of the stall.
The most important part of the stall divider is the lower rail. The lower rail’s purpose is to suggest to the cow just enough, but not too much, where to lie down while allowing her to rise without obstruction or risk of injury.
The height of the lower rail is critical. It must allow for at least a 5-inch (13 cm) gap between the lower edge of the bar and the top of any brisket locator. This will prevent any front leg entrapment below the rail. Low divider rails allow cows to rise with their front legs over the lower rail – leading to entrapment and a cow caught in the middle of the loop. The lower rail must also be high enough, but not too high. High divider rails will at some point prevent side lunge into the adjacent stall, unless they are so high that the cow lunges below them, such as with the Michigan or dog bone loop design.
If the stall is long enough to permit front lunge, a lower rail that prevents side lunge is perhaps permissible. However, on head-to-head stalls, cows in the opposite stall may pose a social obstruction to a subordinate cow, creating a desire to side lunge even when there is space provided in front. For that reason, our preference is to use a divider that allows side lunge, however we do not believe that we should use a divider and stall design that only permits side lunge. Cows that front lunge lie straight in the stall and are cleaner.
The height of the lower rail above the level stall surface (or rear point of the curb in a deep loose bedded stall) should be between 10 to 13 inches (25 to 33 cm) – typically 11 to 12 inches (28 to 31 cm) for mature Holstein cows. The rail should be level and not angle down to the surface (like the green or freedom stall divider). This type of loop will promote side lunge and diagonal lying as the cow takes advantage of the lower rail height at the front of the stall. Loops designed for side lunge (Michigan and dog bone designs), where the cow lunges below the lower rail, also promote diagonal lying, dirty stalls, and medial hock injuries, and are therefore not recommended. Similarly, loops where the lower rail starts level, but bends down to mount onto the top of the stall surface in front should also be avoided since these also invite the cow to lie too far forward and side lunge.
The location and design of the lower divider rail is critical to loop design
The lower rail should extend back toward the rear curb just enough to suggest where the cow should lie straight in the stall, but not so far back that the rail impacts the hooks and rump of the cow as she lies down before it angles upward and out of the way.
From measurements we have taken from countless stalls, we recommend that the angle be 20 to 22 inches (51 to 56 cm) toward the rear curb back from the brisket locator. Since the location of the brisket locator will typically range from 68 to 72 inches (173 to 183 cm) from the rear curb and stall length may vary, we need different sized loops for different sized stalls!
Again, the lower rail is the most important part of the divider – it determines the lateral limits of the resting space, prevents diagonal lying, and allows or prevents side lunge. The rest of the divider loop design is relatively easy!
We prefer dividers that are loops with a level or angled upper rail. The angle allows the cow to pivot her head out of the stall when she is leaving a little easier. The open diameter of the loop determines the height of the neck rail. A distance of 33 to 36 inches (84 to 91 cm) from the upper edge of the lower rail to the lower edge of the upper rail should locate the neck rail at the target height of 46 to 52 inches (117 to 132 cm) depending on the size of the cow. Neck rails determine the standing position of the cow in the stall, and they will always be in the way since cows usually step forward when they rise. However, in a correctly designed stall, provided we have sufficient height, cows will adapt and step backward if we make sure there are no other obstructions to the normal rising movement of the cow.
Lastly, the rear limit of the divider should be 9 to 12 inches (23 to 31 cm) inside of the rear curb, close enough to prevent cows from walking along the back of the stalls, but not so close that it gets hit by passing machinery.
Vertical positioning of the divider loop for mature dairy cattle
Stall Divider Loop Check List:
Mount the lower edge of the lower rail 5 inches (13 cm) above the top of the brisket locator
Upper edge of the lower rail should be 11 to 12 inches (28 to31 cm) above the stall surface
The lower rail should be level with the bed
Angle of the lower rail should bend upward 20 to 22 inches (51 to 56 cm) past the brisket locator
Interior diameter of the loop should be 33 to 36 inches (84-91 cm)
Leave 9 to 12 inches (23 to 31 cm) between the inside of the rear curb and the rear edge of the loop
Location of the brisket locator, lower divider rail, and neck rail in a stall with a 35-inch (89 cm) interior loop diameter. This type of divider has been called a side lunge type because it allows the cow to lunge over the lower divider rail if she chooses to do so. The distance between the brisket locator and the angle of the lower divider rail should be approximately 20 to 22 inches (51 to 56 cm) for mature Holstein cows.
To transfer as much weight as possible from the hind limbs when rising and lying down, the cow moves her head downward toward the ground at the end of the lunge, and then moves her head upward as she completes the rising and lying movement sequence. This area from the stall surface to a height of around 38 to 40 inches (97 to 102 cm) at the end of the lunge is called the ‘bob zone,’ and it must be free of obstruction. We therefore do not recommend accumulation of mounds of bedding, transverse mounting bars, or deterrent bars which impinge on the cow’s head movement in this area.
A bob zone obstruction (box beam) in combination with multiple deterrent wires inhibits normal front lunge movement of the cow’s head
Preferred loop mounting systems include vertically mounted standpipes concreted in, and single beam mounting systems pioneered by GEA Norbco, but are now available from most loop manufacturers. These mounting systems enjoy flexibility in stall width choice and keep the mountings out of the bedding, avoiding rust and damage.
It is critical with these types of systems that the lower edge of the single mounting beam is level with the tops of the cows’ heads at rest, approximately 36 inches (91 cm) above the lying surface. This recommendation is lower than the desired 38 to 40 inches (97 to 102 cm), but with this system a higher beam location will weaken the structure of the stall.
A single beam mounting system correctly positioned to not interfere with the forward lunge of the cow
Divider Loop Recommendations
The below recommendations are for cows 1400 to 1600-lb (640 to 730 kg). Additional specifications for cows of various body weights can be found here.
For a 120-inch (305 cm) long stall with the divider loop anchored 114 inches (290 cm) from the point of the rear curb:
Length of upper rail: 102 inches (259 cm) allows for 12 inches (31 cm) to the rear point of the curb
Length of the lower rail: 64 inches (163 cm) allows for the angle to be at 20 inches (51 cm) behind the brisket locator
Interior diameter of loop: 33 to 36 inches (84 to 91 cm)
Exterior diameter of loop: 37 to 40 inches (94 to 102 cm)
For a 17-foot (5.2 m) head-to-head platform with the divider loop anchored 100 inches (254 cm) from the point of the rear curb:
Length of upper rail: 88 inches (224 cm) allows for 12 inches (3 cm) to the rear point of the curb
Length of the lower rail: 50 inches (127 cm) allows for angle to be at 20 inches (51 cm) behind the brisket locator
Interior diameter of loop: 33 to 36 inches (84 to 81 cm)
Exterior diameter of loop: 37 to 40 inches (94 to 102