Agriculture Reference
In-Depth Information
and quality of animal source foods produced per unit of feed and other resources
invested. Continued improvements in efficiency will be required in the coming
decades to meet future needs. These improvements must be driven by robust funding
for science and technology in plant and animal source foods and for training of new
generations of scientists. These issues have been addressed by Ireland et al. (2008)
and Reynolds et al. (2008).
milk
Milk production in dairy cattle in the United States over a standard 305-day lac-
tation period has increased from about 15,000 pounds in the mid-1980s to about
25,000 pounds in 2006. In many parts of the world, sheep, goats, water buffalo,
reindeer, camels, and other animals are important sources of milk (Ullrey, 2000).
Milk composition is qualitatively similar in all species, but all milk, regardless
of species, has unique properties and constituents needed by all newborn mam-
mals. Improved efficiency of milk production can be expected in all of these
species through new technologies and more appropriate application of tested
technologies.
meat and fish
Swine
In the past two decades, growth rate, feed utilization, and lean meat output in swine
increased from 220 pounds body weight at 5 to 6 months of age and an average back
fat depth of 1.5 inches in the mid-1980s to 270 pounds at 5 to 6 months of age and an
average back fat depth of 1 inch or less.
Chickens
In the United States in the 1980s, it was the norm to market broiler chickens at 9 weeks
of age. In 2005, broilers were marketed at 7 weeks and at a higher market weight.
Sheep
Similar improvements in production efficiency can be cited in lambs per ewe per
year through accelerated lambing and the use of more prolific breeds and improved
pasture management and nutrition.
Fish
Technological advances in commercial fish farming have increased pounds of fish
per unit of feed through improved nutrition and management.
Beef Cattle
The average rate of weight gain during the finishing period is now approaching 4 pounds
daily, compared to about 3 pounds daily two decades ago. This increase is due to a
combination of improvements in nutrition, genetics, animal health, and environment.
Diverse climates create challenges for animal agriculture that are being
addressed by research focused on adaptability of food animals to extremes in envi-
ronmental temperature. Crossbreeding programs using heat-tolerant and disease-
