As a dairy goat breeder I look at structure from a practical viewpoint. What I look for in each animal in my herd needs to be practical so that the goat can be as functionally sound as possible. With kidding season in full swing all over the country, one part of the goat in which good structure is very important is the rump. This is officially the pelvic portion of the dairy goat from hips to pins and from thurl to thurl. It plays so many important parts in kidding and milking, not just one season but over the lifetime of the goat. So, understanding what makes good rump structure and why, is very important for the goat owner to understand.
On the La Mancha, using a cream colored goat so the rump structure is visible, notice the long wide rump that is fully 1/3 of the back from withers (top of the shoulders) to tail. It is flat from front to back and side to side. The front of the pelvis (hip bones) are visible from the top. The pin bones under the tail are wide and open and the thurls are the widest points, wider than the widest part of the udder.
On the Nigerian, the rump is proportionally smaller, just as wide and long, still 1/3 of the length of the back from withers to tail. The thurls are not quite as visible, but are still the widest point and stick out at the top of the thigh where the upper leg attaches to the pelvis. The pin bones on this doe are a bit narrower for her size, though still wide enough to be functional.
First let’s examine the terminology of the pelvis. The prominent hipbones on a four-legged animal, goats included, are the front area of the pelvis bone. The pins are the bony protuberances right behind and below the tail head. The thurls are the tops of the thighbones where they attach to the pelvis. They are normally placed one third of the length of the pelvis, in front of the pin bones and two-thirds behind the hipbones, and should be level with the pin bones.
The udder attachments are hung internally from the pelvis. The whole set of ligaments and fibrous tissue that contains all that wonderful milk, truly hinge on a proper rump shape and angle.
One of the first things I look at in a doe kid who I’m considering keeping is to see if she has a wide rump. That width will give her the structure to kid with ease, giving lots of room for kids to pass. If the rump is narrow, the chances rapidly increase that a kid could get stuck, requiring assistance either manually or thru surgery, to prevent damage to the internal birth passage which could occur due to trauma of passing a kid that is wider than the opening for it to pass through. A wide rump also allows for the width of the udder to hold more milk. The width of the thurls help the legs be wide enough to walk comfortably around a full capacious udder.
The rump should also be long, since the udder attachments are hung from the framework of the pelvis. The ideal length should be one third of the total topline length, with the other two thirds being the loin and the chine. The rump is directly proportional to length and width of attachment an udder can have front to rear and side-to-side.
The ideal dairy goat rump is slightly angled from front to rear, approaching but not quite meeting the level. A bit of angle is needed to assure bodily drainage, so that excess bodily fluids are not trapped inside causing infection.
The udder depends on the rump, in angle as well as width and length, as a more level rump gives more opening under the body to carry an udder that is long from front to back. If the rump angle is steep, angling downward from the hips, it pushes the udder forward which may result in a tilted udder, which often breaks down over time, or in a shorter front to back attachment which has less area to hold as much milk. Levelness from side to side, as well as front to back opens up the body cavity underneath to make room for an open escutcheon, the part of the body where the udder will set as a milker.
I keep all of this in mind as I evaluate each kid born on our farm. My goal is to produce functional and productive dairy goats. Having wide, long and level rumps is one major component helping me meet my goals.