Re-Breeding Nutritional Requirements

Kelley Neuhold, Ph.D.—Tech. Services

“The most economically relevant trait in beef cattle production is reproductive

performance.” -- J.N. Wiltbank, 1994

Nutrient Consumption Reproductive Consequence• Inadequate Energy Intake • Delayed puberty, suppressed estrus and

ovulation, suppressed libido and spermatozoa production

• Inadequate protein intake • Suppressed estrus, low conception, fetal resorption, premature parturition, weak offspring

• Vitamin A deficiency • Impaired spermatogenesis, anestrous, low conception, abortion, weak offspring, retained placenta

• Phosphorus deficiency • Anestrus, irregular estrus• Selenium deficiency • Retained placenta• Copper deficiency • Depressed reproduction, impaired immune

system, impaired ovarian function

• Zinc deficiency • Reduced spermatogenesis

Table 1. Influence of Inadequate Dietary Nutrient Intake on Reproduction in Beef Cattle (Bearden And Fuquay, 1992)

Mature Cow’s Requirement2nd

TrimesterLast

TrimesterLactation

CP, % 6.2 7.8 10.2

TDN, % 45.9 52.6 58.7

NEm, Mcal/lb 0.39 0.49 0.59

Ca, % 0.15 0.25 0.3

P, % 0.12 0.16 0.2NRC, 1996

Young Cow’s Requirement2nd

TrimesterLast

TrimesterLactation

CP, % 6.8 8.6 11.2

TDN, % 50.5 57.9 64.6

NEm, Mcal/lb 0.43 0.54 0.65

Ca, % 0.17 0.28 0.3

P, % 0.12 0.16 0.2NRC, 1996

Target BCS for Rebreeding

• Target BCS was first suggested in 19701

• Literature suggest that ≥5 at calving time to ensure adequate postpartum breeding2

• Cows in BCS 7 to 9 at calving were able to return to estrus with in 60 d no matter BW change pre or post-calving3

1Randel, 19902Dziuk & Bellows, 1983; Richards et al, 19863Whitman, 1975

BCS at Calving No. of cows % cycling 60 d % cycling 90 d

Thin (1-4) 272 46 66Moderate (5-6) 364 61 92Good (7-9) 50 91 100

Body Condition at Calving and Return to Estrus After Calving

Adapted from Whitman, 1975

Effect of BCS at Calving on Postpartum Interval and BCS at Breeding Conception Ratea

Body Condition Score

Post partum interval (d)

Conception Rate (%)

3 (thin) 89 704 (thin) 70 805 (moderate) 59 946 (moderate) 52 1007 (good) 31 100A Adapted from Ken Odde, CSU Department of Animal Science “They are what they eat”

0

10

20

30

40

50

60

1-49 50-99 100-199 200+ All

Perc

ent o

f ope

ratio

ns

Herd size

19972008

Use of BCS Tool by Size & Yr

USDA NAHMS

Energy partitioning by the cow:1.Basal metabolism2.Activity3.Growth4.Energy reserve (basic)5.Pregnancy6.Lactation7.Energy reserve (additional)8.Estrous cycle and pregnancy initiation9.Energy reserve (excess)

Short & Adams, 1988

Energy• Pregnancy rates are greatly impacted by energy

intake• Inadequate energy intake in the 3rd trimester

can reduce pregnancy even with adequate energy intake post-calving

• Further declines are seen when energy intake is inadequate in both periods

• Conception rates of 50-76% with inadequate energy compared to 87-95% when energy intake is adequate

Randel, 1990

Effect of Dietary Energy on Pregnancy Rates in Suckled Cows and Heifers

Adequate* Inadequate* P Source

Pre-Calving

68 60 <0.05 Dunn et al, 1969

78 60 0.1 Bellows & Short, 1978

Post-Calving

95 50 <0.01 Whiltbank et al, 1962

87 64 <0.01 Dunn et al, 1969

92 76 <0.05 Richards et al, 1986

* % PregnantAdapted From Randel 1990

The Current Fad is Fat

Fat Advantages

• Energy dense• Potential reproductive benefits• Improve visual appearance/condition

Fat Disadvantages

• Can depress fiber digestion of high forage diets

• Handling/storage, etc.• Delivering the fat to the cow’s mouth• Can depress overall intake

How much fat/oil can be added to a high forage diet and not decrease

fiber digestion??????

ADDED Fat levels, forage intake and digest

• Hess, et al., 2008--Optimal inclusion levels• Maintain forage digestibility, but fat may

replace some forage– 3% of dietary dry matter or less– May decrease forage intake slightly, but still

increase total dietary energy• Maintain forage digestibility and intake

– 2% of dietary dry matter or less– No change on forage intake

Jenkins, 1987, Mixed Grass Hay incubated with increasing corn oil

0

5

10

15

20

25

30

35

40

0% Corn Oil 2% Corn Oil 4% Corn Oil 6% Corn Oil 8% Corn Oil 10% Corn Oil

48 Hr In Vitro Fiber Digestibility, %48 Hr In Vitro Fiber Digestibility, %

Supports Hess, somewhere between 2-4% added fat starts to depress fiber digestion

Compared corn vs corn oil as energy

• Whitney, et al., 2000—In Vitro data & fed heifers

• Brome Hay @ 9.2% protein was the base• Equal dietary Protein concentration• Equal dietary Energy concentration

– Corn alone– Added 3% corn oil replacing part of the corn– Added 6% corn oil replacing almost all the corn

In Vitro Diets

% of Dry Matter Brome hay only Corn/ SBM

Corn/SBM +3% degummed

Soy oil

Corn/SBM +6% degummed

Soy oil

Brome hay 100 72.3 77.4 81.0

Cracked Corn 18.6 11.9 4

Soybean Meal 5.7 6.3 7.2

Soybean Oil 3 6.2

CP 9.2 11.2 11.2 11.0

ME, Mcal/lb 1 1.09 1.09 1.14

Whitney et al., 2000

In Vitro digestibility

60.468.1 66.1

61.1

24.131

34.829.3

0

10

20

30

40

50

60

70

80

Brome Hay Alone Corn/SBM Corn/SBM+3%degummed soyoil

Corn/SBM+6%degummed soyoil

In Vitro Digestibility, % 24-hr Dry matter disappearance, %

Whitney et al., 2000

*Based on NRC, ‘96 TDN values, the Corn/SBM diet is estimated to be 7.7% more digestible than the brome alone or 65.1%

Feed intake of Heifers in Exp 2 & 3soy oil replaced corn on equal energy basis

Dry basis Corn/ SBM

Corn/SBM +3% degummed

Soy oil

Corn/SBM +6% degummed

Soy oil

Brome hay, lb/hd/d 14.9 14.6 14.5

Cracked Corn, lb/hd/d 3.8 2.3 0.7

Soybean Meal, lb/hd/d 0.18 1.3 1.4

Soybean Oil, lb/hd/d 0.6 1.2

Mineral supp 0.30 0.29 0.29

Total Av. DMI, lb/hd/d 20.2 19.0 18.0

CP 11.2 11.2 11.0

ME, Mcal/lb 1.09 1.09 1.14

Total ME intake Mcal/d 22 20.7 20.5

Whitney et al., 2000

Heifer performance in Exp 2 & 3

Dry basis Corn/ SBM

Corn/SBM +3% degummed

Soy oil

Corn/SBM +6% degummed

Soy oil

Heifer ADG, lb/hd/d Exp 2 1.78 2.0 1.74

Feed efficiency,lb feed/lb gain Exp 2

9.9 8.6 9.4

Exp 2 repro

% pregnant 91.7 90.9 100

% bred AI 67 50 50

Days preg@ preg check 89.4 92.1 89.0

Exp 3 repro

% pregnant 92.9 100 92.9

% bred AI 65 73 54

Days preg @ preg check 93.3 104.6 93.8

Whitney et al., 2000

• Adding 3% corn oil replacing corn maintained or tended to improve the performance of the heifers

• Similar to the in vitro trends, adding 6% corn oil may have suppressed fiber digestion decreasing the energy delivered

Whitney et al., 2000

IMPORTANT: On low quality forages, protein in many cases is first limiting

• Need a Protein, fat, mineral supplement for the greatest potential for improved performance

• 3.5 to 4% of diet DM as fat depresses fiber digestion

• Fat can have positive effects on Reproduction– Females may see a fat effect but source and amount

of fat are important• Linoleic (Safflower)

– Tends to be energy effect rather than a fat effect

Protein• Pregnancy rates can also be greatly impacted

by protein intake• Both pre and post-calving inadequate protein

intake can lower pregnancy rates• Sasser et al. (1989) found pregnancy rates

reduces from 74% to 32% with inadequate protein intake on isocaloric diets

Randel, 1990

Effect of Dietary Protein on Pregnancy Rates in Suckled Cows and Heifers

Adequate* Inadequate* P SourcePre-Calving

84 12 <0.01 Garmendia et al, 1969

58 21 <0.02 Mobley et al, 1983

88 56 <0.11 Fleck & Lusby, 1986

Post-Calving91 71 <0.01 Kropp et al, 1983

95 80 <0.01 Hancock et al, 1985

92 76 <0.05 Rakestraw et al, 1986

* % PregnantAdapted From Randel 1990

When supplementing low quality forages <8% protein, what happens

to forage intake?????

Forage dry matter intake relative to forage crude protein concentrationSource: Adapted from Moore and Kunkle, 1995.

The impact of a small amount (1.8 lbs) of protein supplement on forage intake by

cowsItem No

suppl. + Suppl.%

change

Forage protein content,%TDN of forage, %Supplement protein, %Forage intake, lbsTotal intakeProtein in diet, %TDN in diet, lbs

545-

161657

5454221238

11

+30+41

+49

Montana Beef Network

What happens to forage digestibility when supplementing a low quality

(<8% protein) forage???

DelCurto et al., 1990a532 lb. steers-fed prairie hay

0

10

20

30

40

50

60

Dietary % CP Forage intake Total intake DMdigestibility, %

No supp13% CP Supp26% CP Supp39% CP Supp

Supplements fed @ 2.14 lb/hd/d

At what forage quality level do we lose the improvement in fiber

digestion?????

DelCurto et al., 1990a532 lb. steers-fed prairie hay

0

10

20

30

40

50

60

Dietary % CP Forage intake Total intake DMdigestibility, %

No supp13% CP Supp26% CP Supp39% CP Supp

Supplements fed @ 2.14 lb/hd/d

Cow Nutrition Effects Calf Performance

• Research suggest that cows with adequate nutrition cycle earlier and conceive sooner then cows with inadequate nutrition

• Cows that conceive earlier calve earlier!• Typically age is the great determinate of calf

weight– i.e. calves that are older weigh more

Funston et al., 2012

*

*Conceived 10 days later. French et al, 2012

Take Home• Nutrition and reproduction are highly related• Inadequate protein and energy pre and/or

post-calving can increase postpartum interval and reduce conception rates on first cycle

• Older calves weigh more• 11/21/13 528 lb steers brought $1.91/lb

– $1008.48

Questions?