Livestock On Pasture

Delaware Envirothon Training Susan Truehart Garey

Extension Agent, Animal Science University of Delaware

truehart@udel.edu

Cooperative Extension

Monogastric

• Humans, pigs, dogs, cats, horses, rabbits

• Characterized by one stomach with one compartment

Monogastric • Comprised of:

– Mouth – Esophagus – Stomach – Small Intestine – Cecum – Large Intestine – Rectum

“It all starts with the mouth… open up!”

Monogastric

• Mouth – Where food enters the digestive

tract • Teeth chew to break down food

– Enzymatic breakdown of starch begins

• Saliva is an enzyme which breaks down starch

– The tongue helps move food around and push it to the next part of the digestive system

My teeth are amazingly strong.

Did you know chewing is also

called MASTICATION?

Monogastric • Esophagus

– Tube which carries food from the mouth to the stomach

– Pushes with a series of muscle contractions called PERISTALSIS.

Monogastric • Stomach

– Chamber where chemicals are added to the food

– Cells secrete hydrochloric acid and enzymes

• These help break down food into basic carbohydrates, proteins, and fats

• Some smaller particles are absorbed into the blood stream through the stomach wall

Monogastric Stomach

Monogastric

• Small Intestine – Complex tube which lies in a spiral

• Absorbs nutrients! – Cells produce enzymes to help

break down food further

Monogastric • Cecum

– Known as the “blind gut” – Located between the

small and large intestines – Has little function in the

monogastric digestive system

I have a really big cecum!

Monogastric

• Large Intestine – Shorter than the small intestine, but larger in diameter – Main function is the absorption of water – Mucous is added to the matter to make it easier to pass through

the rest of the system

Monogastric

• Rectum – The terminal portion of the large intestine – Leads to the anus where the remaining wastes are passed

outside of the body as feces or manure

Monogastric Cecum and Large Intestine

• Found in goats, sheep,

cattle, deer, camels, giraffes, llamas and more

• Characterized by one stomach with four compartments

• Used for the digestion of mass quantities of roughages – Hay and grasses

Ruminant (Polygastric)

First Things First

• Ruminant – Primarily herbivores – 4 chambered stomach – Higher proportion of ruminant’s digestive system is

stomach – Major utilizers of cellulose/hemicellulose – 60-75% of ingesta fermented by microbes before

exposed to gastric juices

Mouth

• Tongue – Used more by cattle and goats

• Teeth – No upper incisors- hard palate – Used more by sheep to sort – Lateral chewing

• Saliva – Continual production – Sheep 2 gal /day – No enzymes- high pH

Esophagus

• No sphincter valve • Opens into reticulum and rumen • Muscle contractions move in both directions- rumination or “chewing

cud”

• Reticulum • Rumen • Omasum • Abomasum-”true

stomach”- gastric juices, enzymes

Ruminant Stomach Chambers

The Digestive Tract

Mouth

Esophagus

Rumen

Reticulum

Omasum Abomasum Small

Intestine

Cecum

Large Intestine

50 gallons

Rumen Structures

Reticulum lining-

honeycomb “Hardware disease”

Rumen Structures

Rumen Papillae- finger like

projections

Rumen Structures

Omasum lining- Manyplies

Digestion in the Rumen: Anaerobic Fermentation

It’s All About the Bugs!

Rumen volume lactating cow = 120,000 ml

Rumen bacteria:10,000,000,000/ml

Rumen protozoa: 1,000,000/ml

Rumen fungi: 1,000/ml

Rumen Microbes

Rumen Microbes

Ciliated Protozoa -Colorado State University

Rumen Microbes

How Much Fiber Does a Cow Consume?

Lactating dairy cow eats about 120 lb of wet food containing

about ~ 25 pounds of dry fiber a day

The average adult eats about 1 ounce of dry fiber/day

A human consuming a 10 oz steak eats about 3 ounces of protein

What is the Microbial Protein Worth?

Microbes produced in the rumen supply a cow the equivalent of

15-20, 10-oz steaks/day!

Metabolism Changes with Age • Calves are born with only 1

functioning stomach (like humans) based on glucose as an energy source

• Adult cows are ruminants (4 stomachs) and obtain most of their energy primarily from acids produced in the rumen

More Cool Cow Facts

• Cows chew for 12 hr/day • Chewing produces 50 gallons of saliva per

day • Cows burp 600 liters of methane (CH4) gas per day!

Why Grazing?

• Lower Input – Lower Expenses- Feed for cattle represents major cost in most

production systems – Stored feed 2-3x more expensive per animal then pasture – Less Labor – Less Equipment – Less Infrastructure – Converting solar energy to livestock products

Pasture is Dynamic!

• Constantly changing – New tissue growing at same time old tissue is decaying – Balance between new growth and losses

– Reduce losses by improved grazing efficiency

Herbage harvested Growth-decay

How Do We Increase Herbage Harvested?

• Increase herbage grown – Change environment- overcome deficiencies – Change pasture species

• Decrease herbage lost – Change grazing management☺ – Adapt to pattern of pasture growth – Determined by environment- seasonality, regionality

Environmental Effects on Pasture

• Most critical – Moisture stress in summer – Low winter temperatures

Grazing Management

• Farm subdivision basis for pasture control • Grazing management influences utilization of herbage

grown • Continuous stocking- animals remain on same pasture

for long time – Extreme form- set stocking- no adjustments in stock

numbers despite conditions • Rotational grazing- paddocks grazed in sequence, each

for short time (hours to days) • Both systems adjustments made # animals to control

pasture conditions/animal performance

Set Stocking vs. Rotational Grazing

• Continual grazing of animals on a larger piece of ground for a longer period of time

• Cannot control intake as well

• Herbage wasted by selective grazing

• Lower stocking rates • Older ungrazed material

mowed

• Animals on smaller areas

for shorter periods of time • Continuously moved • Higher stocking rates • More even grazing, less

wasted herbage • Control weeds • Control or limit intake • Control internal parasites

Benefits Rotational Grazing

• Allows intake control • Pasture rationing • Net herbage accumulation increased by

reducing losses, not increasing growth

Different Rotational Grazing Systems

• Strip grazing- temp. elec. fence offer strip pasture in paddock each day- no back fence

• Block grazing- offered pasture daily with front and back fence- extremely high grazing intensity of animals with restricted intake, low residual

• On/off grazing- offered daily pasture allowance and removed from area, reduces hoof damage, leaves more residual for re growth

• All utilized during winter

Stocking Rates for Horses

• Number of horses per unit of land area – Affected by size of horses, age, forage species, soil type, time of

year, environmental moisture, fertility and length of time horses have access to pasture

– research trials- quantify stocking rates as amount of forage per amount of animal weight (lbs. of forage dry matter per 100 lbs live animal)

• General rule is one horse per two acres for majority of diet

• What happens if you overstock?

Pasture Establishment and Fertility • Allow pasture adequate time to get established before

grazing- 1 year spring planted • Root system needs to develop to prevent seedlings from

being pulled out of soil or being damaged by hooves – New forage stands 18-24 months to fully establish – Overgrazing during this time can severely damage – Light, infrequent grazing beneficial – Do not graze closer than 4-6 inches and allow at least 30 days

rest for actively growing pasture • Remember newly seeded as well as renovated

Pasture Establishment and Fertility

• Fertility- – Maintain proper pH – Fertilize as needed- N, P, K – Soil test regularly- every 2-3 years – Keep records – Keep animals off of wet pasture to minimize soil compaction

Nitrogen(N)

• Produces dramatic growth response • Grasses high utilizers of N • Lost through leaching • Legumes- can use soil N or if deficient fix own N from atmosphere

– Use symbiotic rhizobia bacteria – Free living in most soils but can be introduced as inoculum on

seed – Share N with grasses- reduce need for N fertilizer – Don’t need to apply N to pastures with 30% or legume

Phosphorus(P)

• Needed for root growth, seed and fruit formation • Increases survival and growth of seedlings • Usually does not leach

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Potassium (K)

• Used in relatively large quantities • “Antifreeze” for plants- cold hardiness • Important for longevity of stand • Reduce susceptibility to disease

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Rotate and Rest Pastures

• Plants need time to regrow and replenish food sources • Length of rest period depends on time of year and

environment (stresses) • Rotate based on height of plant, not on specific time

schedule • Differences among forage species • Horses are selective or spot grazers- don’t wait for entire

pasture to be grazed to minimum height

Rotate Livestock in Pastures

• Consider grazing different types of livestock in horse pastures – Allows more efficient use – Cattle and sheep are less selective grazers – Grazed more uniformly – Maintain vegetative stage – Cattle and sheep will graze around equine manure piles or follow in rotation – Different parasite profiles

• consume up to 20 percent of their weight daily

• move slowly - approx 30 to 60 bites per minute

• use tongues to draw forage into mouth

• pull or tear it ~ hold it firmly between lower incisor teeth and hard upper dental pad

• graze for 6 to 11 hours per day- 2 major bouts

• cattle rest and ruminate

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Grazing Cattle

• select higher-quality leafy forage

• more nutritious parts of coarse weeds, brush, grasses, and legumes

• wider range of plants than cattle

• tolerate bitter tastes including plants containing large amounts of tannins

• more selective and closer grazing than cattle

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Grazing Goats

• narrower mouths, more flexible lips

• can be more selective- individual bites

• consume a certain amount rest ruminate – sheep/goats 9-11

hours a day • rest and ruminate more

than cattle – 7 to 10 hours a day for

sheep

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Grazing Sheep

Grazing Behavior • Horses are selective grazers

– “Choose the best, leave the rest” • Biting style allows to clip plants close to the ground • Development of lawns vs. roughs

– Lawns- overgrazed forage, allows for erosion and weeds – Roughs- reduced palatability forage

• Preferred, localized elimination areas in larger pastures • Do not graze here

• Lounging areas- when not eating

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Trying to Overcome Selectivity

• Most difficult behavioral trait to overcome! • Time limit grazing? • Rotational grazing • Cultural practices

– Distribute manure piles- dragging – Mowing – Multispecies grazing

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Equine Grazing Management

• Provide adequate land area- reasonable stocking rates • Let pasture get established and maintain fertility • Rotate and rest pastures • Rotate livestock in pastures • Utilize a sacrifice, dry or exercise lot • Provide hay as an alternate forage • Mowing • Manure management

Mowing Pasture

• Selective or spot grazers • Some areas left ungrazed • Clip back to remove mature growth and seed heads,

promote new growth and increase forage quality • Added benefit- slows weed propagation, removes seed

heads • Clip to a height of approx 4 inches • Can not clip too often if minimum height is maintained

but can clip too infrequently

Manure Management • Undergrazed areas of horse pasture generally contain

piles of manure • Compounded by the nutrients in manure promoting plant

growth • Scatter manure piles by dragging with chain harrow or

other implement across pasture • Good after horses have been rotated to a new field or

into sacrifice area and pasture has been mowed • Parasite Control???

Utilize a Sacrifice Lot

• Also called dry or exercise lot • Area where no plants grow • Should be well drained and surrounded by vegetative

buffer • Can improve footing and drainage using geotextile and

1-2 inch rock covered with stone dust and or sand • Used when pasture is too wet, during drought, during

winter (non growing conditions), when fertilizing or whenever pasture is too short to graze

• Remove manure regularly

Resources

• Ball, D.M., Hoveland, C.S.,& Lacefield, G.D., Southern Forages. Potash and Phosphate Institute and Foundation for Ag Research. 2002.

• Bates, A., Food to Feces. CTE Online. Ag and Natural Resources • Boland, H.T., Grazing Behavior Basics. Stocker Cents. April 2011. • Hodgson, J. & White, J., New Zealand Pasture and Crop Science.

Oxford University Press. Auckland, NZ.1999. • Kung, L., Cows Are Cool!, University of Delaware.

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