The Power of Female Proofs in your Herd
Three times per year, the genetic value of bulls and cows is evaluated. You most likely notice the list of bull proofs in different magazines and marketing lists from several AI's. But in addition to bull evaluations, the genetic value of females in your herd is also evaluated each proof round. These genetic evaluations are a powerful tool for selecting the upper and lower end cows in your herd.
What your cows produce, what they look like or how well they get pregnant is called the phenotype. The phenotype is the sum of the genetic value (genotype) of an animal and the environment in which she lives. Examples of environmental factors are housing type, feed-ration and season of calving.
Phenotype = Genotype + Environment
There is a big difference between the genotype and the environment. Unlike environmental factors, the genotype passes on to the next generation animals. It yields permanent and additive improvement in traits of interest over multiple generations. This means that when working with a successful selection strategy you are able to pass on the best genotype to future generations. One selection method is using bulls in your herd which fit your breeding goals. Another selection method is choosing the right cows in your herd to breed and produce the next generation.
To identify the best cows in your herd, use breeding values. Breeding values combine the animal's own data with that all of her relatives. Environmental factors such as age of calving or season of calving are filtered out. Selection on phenotype (e.g. daily lbs of milk) does not use such a filter, therefore, you may select animals that are producing better due to favourable environmental factors and not because they are truly genetically superior.
To demonstrate the usefulness of breeding values to estimate the genetic value of an animal, see the example below which looks at 495 two-year olds in one herd. The Net Merit index is used to rank and categorize the heifers and is defined as expected lifetime profit as compared with the breed base cows born in 2005. This index is expressed as a dollar value and captures the economic impact of the genetics of an animal.
The 495 heifers are grouped in 5 categories:
The table clearly shows that the highest group for Net Merit has the highest Yield for Milk, Fat and Protein and the lowest SCS scores. This confirms that most money can be made with this group of cows. This is also graphically shown in the pictures below.
Selection based on female proofs will help you accumulate the best genetics over future generations, will lead to better phenotypic results in your herd, and overall, will lead to higher profits from your cows.
