Page 115 - Calculating Agriculture Cover 20191124 STUDENT - A

CH 11 Calculating Agriculture 11-3

Example 1. If a beef bull calf has an adjusted weaning weight of 500 pounds, in which the herd
average equals 450 pounds, what is his genetic value? Refer to table 11.1. Heritability
estimates.
Solution:
Probable Genetic Value = herd average + [(bull's value - herd average) x heritability estimate]
= 450 + [(500 − 450) x 28%]
= 450 + [(500 – 450) x 0.28]
= 450 + [50 x 0.28]
= 450 + 14
= 464

Example 2: A heifer with an adjusted weaning weight of 480 pounds from a herd having an
average weaning weight of 470 pounds, what would be the genetic value? Refer to 11
table 11.1. Heritability estimates.
Solution:
Probable Genetic Value = herd average + [(heifers value − herd average) x heritability estimate]
= 470 + [(480 - 470) x 28%]
= 470 + [(480 – 470) x 0.28]
= 470 + [10 x 0.28]
= 470 + 2.8
= 472.8

Example 3: If these two animals are mated, what would be the probable weaning weight?

Solution:
Probable Genetic Value of sire + Probable Progeny Genetic Value of dam
Progeny = —————————————————————————————
2

464 + 472.8
Progeny = —————
2

= 468.4 lbs.

PRODUCTION
When raising livestock the products derived from these animals are meat, milk and breeding
services. In each a major concern are numbers of offspring born and brought to sale. As such birthing
rates are calculated to determine efficiency of the programs. For beef, it is a calf crop, for sheep it is a
lamb crop and for swine the number of piglets farrowed with each birthing. These efficiencies are
also factors of the vigor of bulls, rams and boars, and how many females they can service per day
given the environment that the animals are being managed in.
In calculating our offspring crops, the livestock manager is ultimately concerned with how many
offspring actually make it to market, alive, for sale. To arrive at that number, the following questions
need to be answered:
 How many females are bred and pregnant during the breeding cycle?
 How many offspring are born alive?
 How many offspring are weaned and make it to sale? This is a calculation that includes
offspring morbidity.

It is easy to understand that each of the above values will be different and as they are factors of
each other will affect the percentage of a calf crop, lamb crop, or pig crop.

Large livestock scientists have published the following genetic findings after years of research: Their
study supports that statistically if a sire and dam didn’t have offspring it is likely that the offspring will
perform similarly.
INSTRUCTOR Copyrighted Material