Nutritional Considerations

for the Cow Herd

(based on calving season)

What do they need?

When do they need it?

Energy• Result of CHO and Lipid metabolism

(eg. Converting hay to VFA)

• Requires the majority of feed intake

• Most commonly deficient nutrient for the brood cow

Estimated Net Energy Requirementsfor 2-, 3-, and 5-year old Cows

Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept02468

1012141618 2-year old

3-year old5-year old

Calving

Months Since Calving1996 Beef NRC

Breeding Season

Wean

Mca

l/d

Protein• Cattle have 2 protein requirements

– N needs of rumen bacteria– Amino acids of the animal

• Degradable Intake Protein (DIP)– Breakdown in rumen and supply N to

bacteria• Undegradable Intake Protein (UIP)

– Escape rumen, digested in gut, supply AA

Protein Needs for Cows

02468

101214

1 2 3 4 5 6 7 8 9 10 11 12

Month Since Calving

Cru

de P

rote

in, %

30 lb peak milk production

Macro & Micro MineralsMacro• Salt (NaCl)• Calcium (Ca)• Phosphorous (P)• Magnesium (Mg)• Potassium (K)• Sulfur (S)

Micro• Copper (Cu)• Selenium (Se)• Zinc (Zn)• Manganese (Mn)• Cobalt (Co)• Iron (Fe)• Chromium (Cr)• Molybdenum (Mo)• Iodine (I)• Nickel (Ni)

Mineral Content of Forages

• Grasses are low in P, Mg, Se, Cu, Zn, Mn and others

• Grasses are high in Ca and K

• Grains are low in Ca, K, and many TM

Vitamins• Fat Soluble

– A, D, E and K

• Water Soluble– B complex and C

• For the cow, A is the only vitamin deficient under normal circumstances

Water• Factors affecting water intake

–Temperature–Feed moisture –Body size–Production status

Objective

Meet the nutritional needs of the cow herd as

economically as possible….

…generally on fescue-based pasture systems which minimize the need for stored (hay, silage) or

purchased (supplements) feeds.

Feb. 15 M A M J J A S O N D J

Critical Critical

Goals(Spring Calving Cows)

• Feed a least-cost, balanced ration

• Have healthy, vigorous calves and a good milk supply

• Cycle early and rebreed before extreme heat (in July)

Requirements of Spring Calving Cows

Fescue Production vs. Spring Calvers

Goals(Fall Calving Cows)

• Feed a least-cost, balanced ration

• Rebreed in December/January

• Extra feed for calves during February 15 to April 15 (creep graze or feed)

Requirements of Fall Calving Cows

Fescue Production vs. Fall Calvers

How do you make up the deficiency from pastures?

Allocation of Hay to Various Classes of Cattle Based on Quality

Quality of HayHigh

Low

Classes of Cattle• Young Calves• Weaned Calves• Replacements• Yearlings• Bred Heifers• 2-year old Cows• Lactating Cows• Mature Cows, last 1/3 of

gestation• Mature Bulls• Mature Pregnant Cows, first

2/3 of gestation

How much hay does a cow have to have daily?

Cow and Calf Performance, Feed Intake, lbs

Control Rumensin

Precalving Hay 26.8 23.2

Postcalving Hay 30.5 26.2

SBH 3.5 3.0

Or use your forage analysis to estimate dry matter intake…

120 / NDF (%) = DMI (% BW)

Approximate forage intake by beef cattle

Forage TDN % DMI (%BW)

Well-eared silage 60-70 2.5 to 3.3

Actively growing pasture 70 2.0 to 2.5

Legume hay, good 55-60 2.5 to 3.0

Grass hay, good 50-55 2.0 to 2.5

Mature grass hay 45-50 1.5 to 2.0

Grass hay, poor 40-45 1.0 to 1.5

Straw 35-40 1.0 or less

Find out how much hay the cow will consume

and make up a deficiency with energy or protein supplement

Balance the ration for needed nutrients

Sort Cows and Increase Feed After Calving

Energy Deficiencies Affect

• Cow Rebreeding

• Calf Health/Survival

• Calf Growth Rate

Timing of Deficiency Influences Effect

• Pre-calving deficiency days of post partum interval

• Post-calving deficiency % conception

How do you monitor the nutrition adequacy of

your feeding program?

Beef Cattle Body Condition Scoring

• Reflects adequacy of feeding program

• BCS is a visual assessment of body fat

• Scoring range of 1 to 9, 1=thin, 9=obese

• A score = 4 to 5% empty body fat and 65 to 85 lbs of body weight

Body Condition Score (BCS)in Beef Cows

• Highly related to reproductive efficiency

• Calving time BCS very important

• Thin cows at calving have days return to heat and pregnancy rate

Putting it all together

Forage System 1 (Control)

Fescue-N

Fescue-NBermuda

grass/Cereal Grain

Fescue/Clover

Fescue-N Fescue-N Fescue/Clover

Forage System 2 (High)

= creep gate

Fescue-NBermuda

grass/Cereal Grain

Fescue/Clover

Fescue-N Fescue-N Fescue/Clover

Forage System 3 (Low)

= creep gate

Fescue-NBermuda

grass/Cereal Grain

Fescue/Clover

Fescue-N Fescue-N Fescue/Clover

Forage System 4 (High)

= creep gate

Fescue/Clover

Fescue/Clover

Fescue/Clover

Fescue-N Fescue-N Fescue-N

Forage System 5 (High)

= creep feeder (soyhulls)

Performance of cattle on different forage/management systems (1.6 acres/cow) , 3 years.

Forage Management System

Item SCH SRH SRL FRH FRHCr

Wt. @ breeding, lbs 1,320 1,283 1,287 1,326 1,276

Timed A.I. preg. Rate, %

50.9 60.1 49.7 62.5 71.4

Overall pregnancy rate, %

82.4 88.8 93.6 88.6 95.3

Calving loss, % 8.9 11.1 6.7 4.4 8.9

Performance of cattle on different forage/management systems (1.6 acres/cow), 3 years.

Forage Management System

SCH SRH SRL FRH FRHCr

Averages

Birthdate Mar. 6 Mar. 6 Mar. 11 Sept. 30 Sept. 24

Birth Wt., lb 85.6 89.7 88.1 80.2 79.4

Weaning date Sept. 6 Oct. 17 Oct. 17 June 1 June 1

ADG, lb 2.30 2.18 2.29 2.16 2.27

Adj. 205 day wt, lb 573.1 555.4 572.2 536.8 560.5

Actual wean wt, lb 575.7 580.3 590.2 608.5 650.3

Creep feed (soyhulls), lb, hd

- - - - 821

Differing costs and income per year for different forage/management systems (15 cows on 24 acres)

Forage Management System

Item SCH SRH SRL FRH FRHCr

Income minus differing cost

$4,963.60 $5,482.83 $5,949.08 $5,474.93 $6,071.60

Advantage over unimproved

system, $

- $519.83 $985.48 $511.33 $1,108.00

(Per cow) - $34.62 $65.70 $34.09 $73.87

Latest Research in Mineral Supplementation

Parameter Evaluated Affects Animals Mineral Requirement

Immunity > Fertility > Growth > Maintenance

Factors influencing mineral intake from forage

• Forage mineral content

• Forage mineral availability

• Antagonists

• Dry matter intake

Organic vs. Inorganic Minerals

• Absorbed by a different system

• Use in presence of antagonists

• Better at immune stimulation

Situation:

Selenium (a trace mineral) is presently supplied as sodium selenite at 3X NRC recommended

level, yet deficiencies seem to appear (impaired immunity, etc.) FDA max. daily allowable is 3mg/hd/da in supplement

Effect of Dietary Selenium (Se) Supplementation on Tissue Se Concentration

Item Control NaSe Sel-Plex P Value

Red Blood Cells, mg/ml

0.26 (a) 0.34 (b) 0.42 (c) <.0001

Liver, mg/g 0.26 (a) 0.34 (b) 0.47 (c) <.0001

Flow chart of experimental approaches and molecular bio-techniques used

Tissue collection

Animal trial

RNA extractionSe analysis of blood & liver tissues

cDNA cRNA

Microarray hybridization

Bioinformatic analysis

(By Dr. Mahan’s laboratory)

Liver

Genes Altered by Se Supplementation:Identification of a Common Effect Between Treatments

30 (17,13) regulated dually by

Fisher’s protected LSD (P < 0.05)

125 (P < 0.01)

26 (13,13) regulated by ISe

23 (14,9) regulated by OSe

Implications

• The form of Se supplied in beef cattle mineral mixes matters!

• Therefore, the consequence of recommending inorganic or organic forms of Se to be used in mineral mixes needs to be fully understood from a physiological, and not just economical, perspective.

0 28 56 84 112 140 168 196 2240.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

ControlISeMixOSe

Live

r Se

(µg/

g)

Days on treatment

Effects of selenium on beef cows and their calves

Testis

• Male Calf Testicles– Gestational source of dietary Se affects

neonatal calf testes- affects spermatogenesis, may affect fertility in males

– Maternal source of Se affect steroidogenic gene expression. Can affect androgenesis and estradiol- 17β.

Effects of Se source on blastocyst development from super ovulated beef cows

• More High quality embryos with mix