Nutrition

Feeding grain is common in U.S. feedlots. Corn or maize is the most prevalent, followed by grain sorghum (milo), barley, and wheat. Grain use is based on price, availability, and geographic region. Corn is a relatively abundant and inexpensive energy source containing approximately 70% starch. Feedlot diets generally contain 85% grain such as corn; 5 to 12% forage or roughage such as alfalfa hay, corn silage, or grasses; and 3 to 8% supplement. Diets may contain numerous types of byproduct feeds such as corn gluten feed, distiller's grains, potato wastes, molasses, beet pulp, etc. that may replace 5 40% of the grain, depending on supply, cost, protein, and energy of the by-product feed. Supplements provide protein, minerals, vitamins, and feed additives at appropriate levels based on nutrient requirements of cattle. In feedlot diets, calcium supplementation is required in all cases, owing to the low concentrations of calcium in basal ingredients such as grain. In most cases, unless highprotein by-products are fed, protein supplementation is required to ensure optimal growth of both microbes and the animal. For more information on nutrient requirements and protein nutrition, the reader is referred to the

United States Cattle on Feed 1,000 + Capacity Feedlots

Million Head

Million Head

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec usda-nass 12-19-03

Fig. 1 Graph of cattle on feed or present in feedlots on the first day of each month for 2001, 2002, and 2003. As a general rule, cattle numbers tend to decrease in the summer months, and are greatest in the fall when calves enter feedlots following weaning and as yearlings are brought into feedlots from summer pastures. (View this art in color at www.dekker.com.)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec usda-nass 12-19-03

Fig. 1 Graph of cattle on feed or present in feedlots on the first day of each month for 2001, 2002, and 2003. As a general rule, cattle numbers tend to decrease in the summer months, and are greatest in the fall when calves enter feedlots following weaning and as yearlings are brought into feedlots from summer pastures. (View this art in color at www.dekker.com.)

National Research Council's 1996 publication, ''Nutrient Requirements of Beef Cattle.'' The average feedlot diet, based on a survey of nutritionists, is provided in Table 1,[2] which illustrates how diets are formulated to meet nutrient requirements.

To understand feedlot nutrition, a rudimentary knowledge of ruminants is required. The distinguishing feature for ruminants is the fermentation, digestion, and microbial growth that occurs in the reticulo-rumen. During normal fermentation, microbes digest feed, grow, and produce acid compounds as by-products of their digestion. These acids are referred to as volatile fatty acids (VFAs) and are used by the animal for energy and growth. Common short-chain VFAs produced during fermentation include acetic, proprionic, and butyric acids.

The importance of understanding rumen fermentation is critical for two reasons: 1) when starch (i.e., corn or other grains) is digested too rapidly, cattle may experience negative consequences referred to as subacute and acute acidosis, or too much VFA; and 2) cattle must be slowly adapted from forage diets to feedlot diets (grain-based) over an 18- to 28-day period, commonly referred to as grain adaptation or step-up programs. Acidosis is defined as a series of biochemical events resulting in low rumen pH and reduced DMI (pH<5.6; subacute acidosis) or more severe symptoms including death at very low pH (pH<5.0; acute acidosis). Acidosis is a critical condition that feedlots manage daily to ensure good performance and health.[3]

Grain is normally processed, but can be fed whole. In most large operations, grain may be dry-rolled, fed as high-moisture (24 30% moisture) ensiled grain, or steam-flaked. There is a cost to processing; however, animal performance is improved through improved starch digestion. The effects of corn processing on digestion[4] and on performance1-5-1 has been reviewed, and direct comparisons have been made.[6,7] However, as processing intensity increases, ruminal starch digestion will increase and may cause acidosis-related challenges.

By-product feeding is important in intensive beef production systems, particularly corn gluten feed,[8,9] distiller's grains,[10] and potato by-products.1-11-1

Other Technologies

Implants are steroids usually consisting of estrogenic and androgenic hormones given to cattle for improved growth. Implanting cattle is safe, cost-efficient, effective technology for feedlot operators to utilize. Implants have little impact on tenderness or quality grade of cattle if compared at equal end points[12] and markedly increase finished weight of cattle, by 20 to 40 kg.[13]

Feed additives are commonly used to control disease challenges, improve feed efficiency, or increase weight. Ionophores are a class of compounds that manipulate rumen fermentation, resulting in more proprionic acid

Table 1 Dietary assumptions on nutrients

Nutrient

Average concentration

Minimum concentration

Maximum concentration

CP, % of DM

13.31

12.50

14.0

P, % of DMa

0.31

0.25

0.50

Ca, % of DM

0.70

0.60

0.90

K, % of DM

0.74

0.60

1.00

Mg, % of DM

0.21

0.15

0.30

S, % of DM

0.19

0.10

0.34

Na, % of DM

0.138

0.098

0.197

Cu, mg/kg

14.8

6.0

20.0

Zn, mg/kg

74

50

150

Se, mg/kg

0.21

0.10

0.30

aMaximum concentration of P increased to 0.50%, due to by product feeding in certain regions (From Ref. 2.)

aMaximum concentration of P increased to 0.50%, due to by product feeding in certain regions (From Ref. 2.)

compared to acetic acid. The shift in VFA profiles improves feed efficiency 4%[14] to 7.5%[15] in feedlot diets for monensin. Antibiotics are occasionally fed to beef cattle for health challenges, and for control of liver abscesses. Another class of feed additives called beta-agonists was recently approved for use in beef feedlot cattle. Ractopamine was approved in 2003 for use during the last 28 to 42 days before marketing for increased weight gain and improved feed efficiency.

Why Gluten Free

Why Gluten Free

What Is The Gluten Free Diet And What You Need To Know Before You Try It. You may have heard the term gluten free, and you may even have a general idea as to what it means to eat a gluten free diet. Most people believe this type of diet is a curse for those who simply cannot tolerate the protein known as gluten, as they will never be able to eat any food that contains wheat, rye, barley, malts, or triticale.

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