ASAS CENTENNIAL PAPER: Impacts of animal science research on United States sheep production and predictions for the future1

Abstract

One hundred years ago, there were more than 48 million sheep in the United States. In 1910, they were valued at $4/head, with 43% of income coming from the sale of sheep, lambs, and meat and 57% coming from wool. Over the years, fluctuations in this ratio have challenged the breeder and researcher alike. By 2007, sheep numbers had declined to 6.2 million, with the average sheep shearing 3.4 kg of wool (representing <10% of income), 0.2 kg more than in 1909 but 0.5 kg less than fleeces in 1955. Sheep operations have declined by more than 170,000 in the past 40 yr. A cursory examination of this information might lead one to conclude that animal science research has made little impact on sheep production in the United States. On the contrary, lamb crops in the new millennium (range = 109 to 115%) are greater than those recorded in the 1920s (85 to 89%) and dressed lamb weights increased from 18 to 32 kg from 1940 to the present. In the past century, researchers conducted thousands of investigations, with progress reported in new, existing, and crossbreed evaluations, quantitative and molecular genetics, selection, nutrition, fiber, meat, hides, milk, growth, physiology, reproduction, endocrinology, management, behavior, the environment, disease, pharmacology, toxicology, and range, pasture, and forage utilization such that a vast amount of new information was accrued. Our understanding of sheep has benefited also from research conducted on other species, and vice versa. Many factors that have contributed to the decline in the sheep industry are not influenced easily by academic research (e.g., low per capita consumption of lamb meat, predation, reluctance to adopt new technologies, cost and availability of laborers with sheep-related skills, and fewer young people pursuing careers in agriculture). The size of the US sheep industry is expected to remain stable, with possible slow growth in the foreseeable future. To remain profitable, producers will take advantage of new (or previously unused) technologies, the desire of the public for things natural, domestic niche and international fiber markets, and the ability of the sheep to control noxious weeds and thrive in suboptimal ecosystems.

Characterization of the productive performance of Highlander sheep in Southern Chile. I. Female reproductive traits

“…Maternal traits that affect the production of weaned lambs are ovulation, fertilization and gestation efficiency, and maternal ability to raise the lamb thereafter (Snowder and Foggarty, 2009;Leeds et al, 2012). Seasonality, by facilitating the access to the markets (Notter, 2002;Kleemann et al, 2006) and carcass traits using terminal sires will add value to the lambs (Fogarty and Milholland, 2014 Basic information on the reproductive potential of any breed is required to establish sound procedures for reproductive management including the application of assisted reproductive technology (Notter, 2002;Lupton, 2008;Delgadillo et al, 2014). The present study aimed to characterize the reproductive function of average Highlander sheep.…”

“…Sustainable sheep production systems are based on valuable lamb sold per ewe exposed to rams under balanced cost of production (Lupton, 2008;Snowder and Foggarty, 2009;Fogarty, 2009). Under this context prolificacy and survival of twin lambs have the most critical impact in sheep productivity (Young et al, 2014).…”

Blood Chimerism Confounds Genetic Relative Susceptibility Testing for Classical Scrapie in Sheep

“…16,24 Where detection of chimeras is deemed an appropriate adjunct to other genetic testing being performed, the results of the current study suggest blood samples are preferable.…”

“…One technology that has the potential for commercial cost-effectiveness might be DNA microarray technology 39 because this platform could be adapted to sensitive detection of unusual genome complexity in addition to trait analyses and other genomics applications. 16,24 None of these methods discriminate natural chimerism from sample contamination between individuals as the cause of detecting a complex genome, but replication of results after controlled resampling diminishes the possibility of inadvertent cross contamination. Because mitochondrial DNA is maternally inherited, 40 codetection of a complex mitochondrial genome might also be used as evidence most consistent with cross contamination.…”

Livestock breeding for sustainability to mitigate global warming, with the emphasis on developing countries

“…However, reproduction (ewe productivity) and its components are the traits that are universally important, because performance in these two traits define the efficiency and profitability of a sheep enterprise (Snyman et al, 1997;Olivier et al, 2001;Lupton, 2008). The biggest single opportunity for increasing the efficiency of lamb meat production is through an increase in the number of lambs marketed per ewe per year (Shelton, 1971).…”