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Basics of Beef Cattle Nutrition

Bryan Doig, PAgLivestock Development SpecialistSaskatchewan Agriculture and FoodNorth Battleford 446-7477

April 19, 2007

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A Cow’s Digestive System

A Cow has four stomachsReticulum - The honeycomb" It sorts particles by size, this allows for better breakdown of food. Rumen - "The fermentation vat" The largest compartment that is key to volatile fatty acid absorption. It is like a 55 gallon tank. Its capacity can vary from 46 to 70+gallons in a mature cow.Omasum - The folded structure" It traps particles within the folds, where the particles are squeezed to remove water prior to delivery to the abomasum. Abomasum – “The true stomach" This is where the final breakdown of digestion takes place. 60 to 120 litres of Saliva produced each day – helps to buffer the rumen –maintains a more constant pH level.

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The Rumen

RumenThe rumen is a large fermentation vessel that can contain as much as 220 to 265 lbs of digesting material. Fiber particles remain in the rumen from 20 to 48 hours because bacterial fermentation of fiber is a slow process. However, particles that digest faster tend to stay in the rumen for a shorter period of time. ReticulumThe reticulum is the "crossroad" where particles entering or leaving the rumen are sorted. Only particles that are small is size (< 1-2 mm) and dense (> 1.2 g/ml) may move on to the third stomach. OmasumThe third stomach or omasum is round (Figure 1) and has a capacity of about 10 liters. The omasum is a small organ with great absorption capacity. It allows the recycling of water and minerals such as sodium and phosphorus which return to the rumen through the saliva. Since the modes of digestion in the rumen and the abomasum differ drastically, the omasum acts as an organ of transition between these two organs. The omasum is not essential, however, as it is absent in camels, llamas and alpacas (pseudoruminants). AbomasumThe fourth stomach is the abomasum. This stomach is like the stomach of non-ruminants. It secretes a strong acid and many digestive enzymes. In non-ruminants, ingested feeds are first digested in the abomasum. However, the material entering the abomasum of a ruminant is made up primarily of unfermented feed particles, some end-products of microbial fermentation and microbes which grew in the rumen.

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the “Bugs”

THE RUMINAL BACTERIAThe rumen provides a suitable environment with generous food supply for microbes to grow and reproduce. The absence of air (oxygen) in the rumen favors the growth of some particular species of bacteria, among them are those that can degrade plant cell walls (cellulose) into simple sugars (glucose). The microbes ferment glucose to obtain energy to grow and they produce volatile fatty acids (VFA) as end-products of fermentation. The VFA cross the rumen wall and become the major sources of energy to the cow. As ruminal microbes grow, they synthesize amino acids, the building blocks of proteins. Bacteria can use ammonia or urea as nitrogen sources to build amino acids. Without bacterial conversion, ammonia and urea would be useless to the cow. However, bacterial proteins synthesized in the rumen are digested in the small intestine and constitute the major source of amino acids for the cow. How Rumen Microbes Process FeedFeed digestion in cattle is a two-step process. First, the bulk of the feed consumed by the animal is digested by microbes in the rumen. Second, the microbes and any residues they have not broken down are digested by the animal itself. Microbial digestionBefore microbes begin the process of digestion, they must first attach themselves to feed particles. They do this by secreting a sticky, mucous-like envelope onto the feed which serves as a bridge for attachment and reduces their chances of being washed off.Once attached, microbial cells multiply to form colonies at the site of attachment and begin to release digestive enzymes which break down the feed. The

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the Remarkable Ruminants

Video “The Remarkable Ruminants”

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Concept of Dry Matter

52

12.1

12

23.9

47

9.211

32.8

39

3.511

46.5

23

4.3

61

11.7

Ash, Minerals, etc.MoistureCrude ProteinTDN - Energy

Alfalfa-GrassHay

Grass Cereal Cereal Hay Straw Silage

Feeds out of the pail or by the bale.All feeds contain moisture or water.It is difficult to compare the nutrients from one feed type to another.

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Concept of Dry Matter

Ash, Minerals, etc.Crude ProteinTDN - Energy

Alfalfa-GrassHay

Grass Cereal Cereal Hay Straw Silage

59.1

13.8

27.2

52.8

10.3

36.9

43.8

3.9

52.3

59

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Remove the water

100 % Dry Matter

Take the moisture content to zero and nutrient comparisons can now be made.You can now compare “apples to apples”

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Water Quality

Water is the single most important nutrientWater is never “pure”Water may contain

dissolved mineralspollutantsmicro-organismssuspended solidsorganic and inorganic compounds

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Water Quality

a measure of all the inorganic compounds dissolved in the waterTDS provides a useful measure of the suitability of a water supply for livestock

Total Dissolved Solids - TDS

7000 + Unsatisfactory5000 – 7000 Diarrhea in Lactating Cows4000 – 5000 Useable3000 – 4000 Fair1500 – 3000 Good

< 1500 Very Goodppm or mg/litre

TDS Concentration Usefulness for Cattle

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Water Quality

Sulphates

3300 + Unsuitable for lactating cowsand cause deficiency problemsmay interfere with Copper absorption

800 + Sulphate levels higher than 800 mg/l500 – 3000 Laxative Effect

< 500 No Problemsppm or mg/litre

Concentration Usefulness for Cattle

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Water IntakesRequirementsCows Calves Feeders Feeders

to 500 lbs to 750 lbs to 1100 lbs

Daily Demand Gallons per 1100 lbs liveweight

- Average 10 10 (5) 10 (7) 10

- Hot Weather 20 20 (10) 20 (14) 20

Surface Area Required 4 square feet per 100 head

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Energy

• Loss of body weight and condition

• Inability to keep warm

• Loss of performance

TDN = total digestible nutrients

“Fuel for the body”

Inadequate energy causes . . .

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Crude Protein

Plays an important role in . . .

• digestion and body functions

• muscle and skeletal growth

• feeding the “microbes” in the rumen

• “by-pass” protein

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Calcium

Plays an important role in . . .

• growth and lactation

• digestion and enzyme activity

• deficiency symptoms include

• slow growth, stiff tendons

• retained placentas

• stillborn calves

Maximum calcium content is 1.0% of Dry Matter Intake. Calcium functions in building and maintaining the structures of bone and teeth, initiation of the clotting of blood , maximal activity of digestive enzymes and is involved as part of the messenger system in the body. The body uses both active and passive transport systems to absorb Ca from the intestine in response to parathyroid secretion . Absorption is increased by arginine chelation and lysine but decreased by oxalates, phytates and phosphates. Deficiencies include rickets in the young, osteomalacia in mature animals, and slow growth. Low dietary Ca levels, vitamin D deficiency, hypoparathyroidism, renal insufficiency or excessive P dietary levels are some of the causes of Ca deficiency. Hypercalcemia does not normally occur because excessive Ca is not absorbed. Calcium is abundant in grasses, legumes and some oil seeds. It is limited in grains and supplementation is common with grains. Acceptable ratios are from 1.5:1 to a maximum of 7:1. Calcium levels are affected by K and Mg.

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Phosphorus

Plays an important role in . . .• energy transfer in the body

• genetic, enzyme and blood systems

• deficiency signs include

• slow growth, reduced appetite

• reduced feed efficiency

• low milk production

• “silent heat”, lowered fertility

Maximum phosphorus content is 0.6% of DMI. Phosphorus functions in bone and cell membrane structures, genetic, energy, enzyme and blood buffering systems. Phosphorus absorption involves both active and inactive systems but is independent of Ca absorption. Over 90% of P can be absorbed on P deficient diets. However, the availability of P is rather low (about 15 to 20 percent). Presence of fatty acids, aluminium and ions which can form complexes with P in the gut decrease P absorption. Deficiency symptoms include slow growth, pica, low appetite, low conception rates, reduced feed efficiency and low milk production. Toxicity can occur when Ca and Mg phosphates precipitate in the urine (the cause is urinary calculi). Although cattle may receive sufficient P when fed high grain diets, supplementation is normally required for most classes of cattle. Acceptable ratios are from 1.5:1 to a maximum of 7:1.

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Sulphur

• High levels of sulphur in the diet interferes with copper absorption. Problems occur when sulphur levels exceed 0.35% diet dry matter.

• At increasingly higher levels and where the sulphur is readily absorbed, “P.E.M.” orpolioencephalomalacia can result, causing scarring of the brain tissue and death.

Sulphur is needed at 0.15% of the diet for all cattle. Maximum tolerable level is 0.40%. Sulphur is a constituent of the amino acids methionine and cysteine. Sulphydryl compounds are involved in the activation of various enzymes, formation of adrenaline and creatine, bone calcification and prevention of enzymes from damaging epithelial cells. Most absorption of S occurs in the small intestine as part of amino acid sulphur. In the rumen, dietary S is usually degraded to sulphide and then re-used in the formation of microbial protein. Deficiency symptoms are very varied due to the varied functions performed by S. Toxicity can lead to polioencephalomalacia (P.E.M.). Excess sulphur from either the diet or water interferes with copper availability. Sulphur present in water is additive to sulphur present in the feed or forage.

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Potassium

Excess potassium (over 3.0% of ration DM) may interfere with magnesium absorption and reduce feed intake

Cereal greenfeed or silage can have high levels of potassium (1.8% to over 5.1%)

High levels of potassium can contribute to milk fever. Measure using the DCAB ratio. Can also affect the Tetany Ratio (K / Ca + Mg).

DCAB = Dietary Cation Anion Balance (Na+K)-(Cl+S)

+400 to 450 or more = hypocalcemia

Growing and finishing cattle and gestating cows need 0.6% of DMI as potassium. Lactating cows need 0.7% potassium. Maximum tolerable level is 3% of DMI. Potassium functions in the acid-base balance of the body, enzyme systems, glucose and amino acid uptake, and blood pressure regulation. Absorption is mostly by passive means. Several hormones including antidiuretichormone, aldosterone (decrease), glucocorticoids (decrease), insulin and glucagon (increase), influence K levels in the body. Deficiency symptomsinclude abnormal electrical activity of the heart, slow growth, stiffness, convulsions and even death. Deficiency can occur in animals fed high grain diets and during stressful situations. A small increase in blood K can be toxic The dietary K/(Mg+Ca) ratio should not exceed 2.2:1. High dietary K reduces absorption of magnesium but increases calcium absorption from the intestine. Potassium is involved in the DCAB calculation. At present there are no DCAB recommendations for beef cattle. Problems with milk fever start to appear when the DCAB values start to exceed 400.

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Copper

10 to 16 mg/kg of feed (ppm) depending on sulphur and molybdenum intake

1400 lb cow requires 166 mg to 265 mg/day

Maximum intake is 100 mg/kg of feed

more than 0.25% sulphur and 2 ppmmolybdenum increases the requirement

800 ppm sulphate in water is equivalent to about 0.24% sulfur in the ration

some strains of cattle require more copper

Deficiency symptoms include reduced fertility, retained placentas, faded hair coat

Copper is needed at 10 mg/kg of diet for all cattle. Maximum level is 100 mg/kg of diet. It is absorbed in all parts of the gut, with high levels found in the liver and brain. Absorption of Cu is decreased in the presence of excess calcium, zinc, cadmium and iron. In addition, high levels of molybdenum and sulphur influence the availability of copper through the formation of insoluble and unabsorbablecopper sulphide. Molybdenum inhibits sulphide oxide which is required to release Cu from copper sulphide. Copper availability is increased by chelationwith amino acids, citrate and high protein diets. It functions in various enzyme systems including desaturase enzymes. The dietary Cu:Mo should ideally be greater than 6:1, borderline at 2-3:1 and toxic if less than 2:1. Blood Cu levels are not acceptable unless extremely low. Levels in the liver are more acceptable.

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selenium

0.3 mg/kg of feed

1400 lb cow, range 3.3 mg to 12 mg

Selenium deficiency can cause white muscle disease, stillborn calves, weak calves, reduced fertility, “silent” heat, retained placentas and reduced immune system

“narrow window” of supplementation. Toxicity problems do occur from over-feeding Selenium. Loss of hair, cracked hooves and lameness, weak or stillborn calves and abortions all result from excess dietary Selenium

New regulations by the Canadian Food Inspection Agency specify that the maximum level of Selenium in prepared beef cattle minerals cannot exceed 30 mg/kg. The maximum levels in trace mineralized salt cannot exceed 120 mg/kg. “White muscle” areas of the province include the Black, thin Black and Grey-Wooded soils. These soil types are common in the Parkland region of Saskatchewan.The NRC requirement for selenium is 0.1 mg/kg but a more practical level is 0.2 mg/kg. Maximum tolerable level is 2.0 mg/kg. Absorption in association to methionine and cysteine is almost 100% with inorganic sources about 60-70% efficient. Excretion occurs through the urine, bile and pancreatic juice. Deficiency symptoms include white muscle disease, loss of condition, retained placenta, lameness and diarrhea. Toxicity can cause loss of tail hair, sloughing of hoofs and death from respiratory failure. Selenium and vitamin E perform related functions in the muscle, one can replace the other to an extent but not completely.

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selecting Salt

Look for products with these levels of trace minerals

Trace Mineralized Fortified Salt• 2500 to 3000 mg Copper

• 5000 to 8000 mg Zinc

• 10000 to 12000 mg Manganese

• 90 to 120 mg Selenium

Blue Salt = salt + cobalt + iodine

Blue Salt is “1962” technology. Our cattle have 2000 genetics. It is generally advisable to use the newer Trace Mineralized Fortified Salts which, in addition to Cobalt and Iodine, contain Copper, Manganese and Zinc. They can be purchased with or without Selenium.A daily intake of 1.5 oz salt containing 120 mg/kg selenium provides 5.1 mg of seleniumA daily intake of 1.5 oz mineral containing 30 mg/kg selenium provides 1.3 mg of seleniumSalt plus mineral gives a total of 6.4 mg of selenium – well within the window for seleniumintakes in “white muscle” areas of the province.

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choosing Minerals

Look for products with these levels of trace minerals

Minerals• 2500 to 3000 mg Copper

• 5000 to 8000 mg Zinc

• 10000 to 12000 mg Manganese

• 30 mg Selenium

Minerals need to be fed every day

Mineral supplements are used to balance or correct deficiencies of required minerals that may or may not be present in the feed.There are many commercially available beef cattle mineral products available in the market. They are often described as a 1:1, 2:1, 3:1 or 0:1 ratio. This ratio is determined by the amount of Calcium compared to the amount of Phosphorus contained in the mineral (expressed as a percentage). A 1:1 mineral may contain 15% Calcium: 15% Phosphorus or 18% Calcium: 18% Phosphorus or any other equal amount of Calcium and Phosphorus. A 2:1 mineral may contain 18% Calcium: 9% Phosphorus or any other blend, but it will always have 2 parts of Calcium for every one part of Phosphorus. Commercial mineral products may also contain other minerals such as Copper, Zinc, Manganese, Selenium, Vitamins A, E and D, medicating ingredients and ionophores.

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vitamin ACows require 40 to 50,000 IU’s of Vitamin A per day (Lactating 70 to 80,000 IU’s)Grains and weathered forages do not supply any Vitamin AHigh nitrate levels impair Vitamin A uptakeLiver will store Vitamin A up to 90 daysVitamin A deficiencies include retained placentas, abortions, stillbirths and weak calves, reduced fertility and lowered conception rates, reduced immune response, night blindness and an increase in “water belly”Vitamin A can be injected or fed once per week

Vitamin A content of each feed is expressed in thousands of international units (KIU) per kg and Ib. Recommended and supplied levels of vitamin A are expressed as IUs. Recommended values are 2200, 2800 and 3900 IU/Kg DMI for growing/finishing, gestating and lactating cattle, respectively. Vitamin A is a generic term and refers to all compounds other than carotenoids (pro-vit A), with vitamin A activity. Vitamin A is fat soluble and is absorbed in the gut mainly as free retinol and carotenols but is esterified with long-chain fatty acids and released into the lymph as chylomicrons. Over 90% of vitamin A is stored in the liver. Light and oxygen oxidize vitamin A and usually over 90% of activity is retained for periods up to 6 months but stability is reduced by pelleting and in the presence of trace minerals. Excretion is in the bile and urine. It functions in vision, growth, glycoprotein formation, reproduction, maintenance of mucus membranes and immunity. Deficiency symptoms reflect the many functions of vitamin A. Toxicity results in bone abnormalities, loss of hair, poor growth and congenital abnormalities. Toxicity problems of Vitamin A are rare as extremely high amounts would have to be fed over a long period of time.

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The Basics Thumb rules . . .

• cows do not eat percentages

• cows do not eat decimal points

• cows know nothing about nutrition

Once cows are on a balanced ration, monitor their condition to ensure that the feeding targets are being met.

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Feeding Cattle

Cows will only balance 4 things . . .• the air they breathe

• the water they drink

• dry matter intake

• salt

It is up to us to supply properly balanced winter rations

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feeding exampleOne square bale of hay weighs about 65 lbs

During lactation, a 1200 lb cow will eat about one-half of a bale each day. If that is the only feed that is provided – this is the result

The cow is losing 0.82 lbs of body weight per day

The diet is deficient in TDN (energy)Phosphorus Vitamin A

Copper Zinc

Manganese

Selenium

1200 lb cow lactating AprilAlfalfa-Grass Hay – average feed values Crude Protein 14 % TDN Energy 61 %The cow will lose ½ of a Body Score in 130 days or 7 % of her body weight 1200 lbs X 7% = 84 lbs in 103 days = a loss of 0.82 lbs per day

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example of a balanced ration

Feeds and Intake

Alfalfa-grass Hay 22.0 lbs

Straw 2.0 lbs

barley or oats grain 7.0 lbs

1200 lb Cow lactatingMonth of April

1:1 Mineral 1.5 oz per day

Vitamin A 0.2 oz per day (10 million IU per Kg)

Fortified Salt 1.5 + oz per day Free Choice

current month temperature 5 Cprevious month temperature -5 C0.19 lbs ADGexpected calf birth weight 80 lbs

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Basics of Beef Cattle Nutrition

Questions

Comments

Concerns

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end of presentation

Bryan Doig, PAgLivestock Development SpecialistSaskatchewan Agriculture and FoodNorth Battleford 446-7477