Agriculture Reference
In-Depth Information
Probiotics
Probiotics are live microorganisms that may confer health benefits in the host ani-
mal (mainly cattle, swine, and poultry) and in humans when provided in appropriate
amounts (Gilliland, 2005; Sanders et al., 2007). They have received attention as a
potential alternative to antibiotics, but inconsistent results have been reported in ani-
mals.
Lactobacillus acidophilus, L. casei,
and
L. fermentum
have received the most
attention in animals.
enzymes
Some
enzyme additives are useful in improving digestibility of nonstarch polysac-
charides (carbohydrates). Supplementation of the feed with these enzymes may have
use in improving utilization of these polysachharides in some cereal grains (Newbold
and Hillman, 2005). The most promising application of added enzymes in the diet is
that of phytases to improve the utilization of phosphorus in cereal grains. Reduction
in excretion of unused phosphorus in the diet improves performance of pigs and
poultry and may result in large decreases in phosphorus entering the environment
and eutrification of streams and bodies of water This technology has been adopted
by the feed industry (Lei and Porres, 2005).
Ionophores
A group of compounds, notably monensin and lasalocid, influence rumen fer-
mentation in cattle when added to the feed and have had a major impact on
animal agriculture by increasing milk yield in dairy cattle, reducing methane
production, and improving feed utilization and growth in feedlot cattle. These
dramatic responses have resulted in major saving of natural resources to animal
agriculture (McGuffy, 2007). Ionophores are technically antibiotics but are usu-
ally classified separately because they act by very different mechanisms than
other antibiotics and are not used much as antimicrobials for humans. There is
also hope among manufacturers of these compounds and the companies that use
them that, if broad-brush bans on antibiotics use were passed, ionophores might
be spared.
Protein Anabolic Agents
A class of compounds known as β-adrenergic agonists (β-agonists, repartitioning
agents) has been used for about two decades to enhance lean tissue and decrease
fat in beef cattle and swine (Anderson et al., 2005). The β-agonists have been used
safely for many years in human medicine as bronchodilators for asthma and as uter-
ine relaxants in pregnancy to arrest premature labor. Approval by the U.S. FDA for
use as feed additives resulted in their rapid acceptance to enhance carcass leanness,
decrease fatness, and improve growth efficiency.
