The ornamental design for a cattleimmobilizer, as shown and described.
FIG. 1 is a first perspective photorealistic view of the design of the cattle immobilizer of the present invention from the top, left, back perspective.
FIG. 2 is a second perspective photorealistic view thereof from the top, right, back perspective.
FIG. 3 is a third perspective photorealistic view thereof from the right, back perspective.
FIG. 4 is a fourth perspective photorealistic view thereof from the front, left perspective.
FIG. 5 is a right side photorealistic view thereof, with a left side photorealistic view being a mirror image thereof.
FIG. 6 is a back photorealistic view thereof; and,