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 Requirements for 2-, 3-, and 5-year old Cows Calving Months Since Calving 1996 Beef NRC Breeding Season Wean Mcal/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 30 lb peak milk production

Macro & Micro Minerals Macro 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. 15MAMJJASONDJ 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 Hay High 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 ControlRumensin Precalving Hay Postcalving Hay SBH3.53.0

Or use your forage analysis to estimate dry matter intake… 120 / NDF (%) = DMI (% BW)

Approximate forage intake by beef cattle ForageTDN %DMI (%BW) Well-eared silage to 3.3 Actively growing pasture702.0 to 2.5 Legume hay, good to 3.0 Grass hay, good to 2.5 Mature grass hay to 2.0 Grass hay, poor to 1.5 Straw 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

Bermuda grass/ Cereal Grain Fescue/ Clover Fescue-N Fescue/ Clover Forage System 2 (High) = creep gate

Fescue-N Bermuda grass/ Cereal Grain Fescue/ Clover Fescue-N Fescue/ Clover Forage System 3 (Low) = creep gate

Fescue-N Bermuda grass/ Cereal Grain Fescue/ Clover Fescue-N Fescue/ Clover Forage System 4 (High) = creep gate

Fescue/ Clover Fescue/ Clover Fescue/ Clover 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 ItemSCHSRHSRLFRHFRHCr breeding, lbs1,3201,2831,2871,3261,276 Timed A.I. preg. Rate, % Overall pregnancy rate, % Calving loss, %

Performance of cattle on different forage/management systems (1.6 acres/cow), 3 years. Forage Management System SCHSRHSRLFRHFRHCr Averages BirthdateMar. 6 Mar. 11Sept. 30Sept. 24 Birth Wt., lb Weaning dateSept. 6Oct. 17 June 1 ADG, lb Adj. 205 day wt, lb Actual wean wt, lb Creep feed (soyhulls), lb, hd

Differing costs and income per year for different forage/management systems (15 cows on 24 acres) Forage Management System ItemSCHSRHSRLFRHFRHCr Income minus differing cost $4,963.60$5,482.83$5,949.08$5,474.93$6, Advantage over unimproved system, $ -$519.83$985.48$511.33$1, (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 ItemControlNaSeSel-PlexP Value Red Blood Cells, mg/ml 0.26 (a)0.34 (b)0.42 (c)<.0001 Liver, mg/g0.26 (a)0.34 (b)0.47 (c)<.0001

Flow chart of experimental approaches and molecular bio-techniques used Tissue collection Animal trial RNA extraction Se 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.

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