University:
Sam Houston State University
Course:
BIOL 2413 | General Zoology
Academic year:

2022
Views:

31

Pages:

11
Author:

larbiwxcvbn

• Meat Goats – Examples: Boer, Spanish, Hejazi (Arabia), Kiko (New Zealand) • Dual purpose goats: meat and milk – Probably most of the species in the world are dual purpose • Fiber Goats: Cashmere, Angora Matching Breeds to Markets • Breeds should be chosen primarily on the basis of climatic adaptability and compatibility with other production conditions, but performance and marketability should also be considered. Selection of Individuals for Breeding • Select only for traits that have some bearing on herd or flock profit or objectives. • Use the most objective measures when available. • If there are no objective measures, be sure any visual methods are meaningful and affect profit. Most Important Traits • Reproductive performance - highest economic value • Maternal ability - including milk production • Growth and efficiency - weaning weight, postweaning gain, yearling weight, feed conversion • Market price - with traditional live methods by weight, or carcass grids, or by the head as replacements • Temperament (cattle) Flocking instinct (sheep goats) ease of handling • Longevity - length of productive life In dairy and beef cattle, selection can be most accurate and most effective using Expected Progeny Difference (EPD) EPD • Adjusts for differences in environment, such as climate and nutrition. • Can be compared within a breed for all individuals (males and females) in all locations and management systems across all years. Also can be used to compare EPDs within one breed for crossbreeding, such as comparing Angus sires to be used on Hereford cows. • Procedures have been developed for comparing EPDs of different breeds, but these are less reliable than within-breed EPD. EPD ACCURACY • Every EPD has a value for Accuracy. • Accuracy is a measure of confidence that the EPD is the true genetic value. • Accuracy ranges between 0 and 1. • High Accuracy requires significant number of progeny records on an individual. Young animals with pedigree data only have low Accuracy, but the EPD is still useful for selection. SELECTING WITHOUT GENETIC DATA Use visual appraisal for: - Structural soundness - Breeding soundness - Udder capacity and soundness - Indicators of productivity and adaptability (such as body capacity, fleshing ability) - Visible factors affecting market price (such as color, muscle thickness, breed/type)