USING SCIENCE TO IMPROVE FERTILITY IN BOS

INDICUS CATTLE

F.W.C. Neser

Efficiency of productionCountry % Off-take

South Africa (Commercial) 32

South Africa (Emerging) 21

South Africa (Communal) 6

Australia 28

New Zealand 37

European Union 34

USA 38

Argentina, Uruguay 30

Brazil 22

Source -National beef Cattle Sector Strategy and Implementation Framework – February 2006

Stud vs. Commercial vs. Communal

Communal Commercial Stud

Calving % 40% 65% 85%

Pre-wean mortality 50% 4% 2%

Post-wean mortality 15% 2% 2%

Calves wean/annum/25 cows 5 16 21

Calves available for sale 2 15 20

Average weight 150kg 180kg 205kg

Price/kg R9.00 R20.60 R21.25

Potential monetary value R2700 R55620 R86100

Potential monthly income R225 R4635 R7175

Fitness

Fitness = NATURAL SELECTION:

Survival

Fertility

The heritability of fitness traits are usually low and will be severly influence by inbreeding depression and heterosis (Bourdon, 1997)

Unlike the dairy farmer, the beef farmer derives his entire income from calves born into the herd, making fertility unquestionably the most important trait. Results of a study placed the economic importance of fertility, growth rate and carcass quality in the ratio 10:2:1. This means that fertility is 5x more important than growth and 10x more than carcass quality (Dr G Coulter-Kanada)

Differences in Gross margins using a medium frame cow and different fertility levels

65% 75% 85% 95%260,000

280,000

300,000

320,000

340,000

360,000

380,000

400,000

Medium Frame WeanerFarm size 1000haStocking rate 6ha/LSUWeaner price R 17.00Carcass price R 27.00Price of C grades R 23.00

Perceptions on Fertility

All animals are equally fertile

It is impossible to improve fertility by selection

Feed your animals fertile

Phenotype

Genotype

Environment

Model

P = μ + G + E

Environment

Nutrition & management that affect the animals in the

herd now! Cows:

• manage heifers to attain mating weights (65% of adult weight)

• manage 1st calf cows (e.g. early weaning & mate separately)

• restrict joining & cull empties

• control reproductive diseases

• cull females having difficult births

Bulls:

• breeding soundness test (adequate scrotal size)

• good physical structure (and sheath)

• adequate pre-breeding nutrition (body condition)

• control reproductive diseases

• multi-sire groups, mating ratios, serving

capacity

Fertility

Female fertility is a complex trait with many components.

Each component use resources. Nature select for intermediate optimum. Holistic approach. To much selection emphasis on

production could decrease reproduction

Did not calf

Less fertileAbove average fertile

Genetics

Traditional fertility traits in females

Age at first calving (Optimum) ICP: First and second calf (Min) Average lifetime ICP (Min) Days to calving

• whole herd recording (female inventory) bull in date and service sire(s) subsequent calving date record culls, especially non-calvers /culled empty

Traits Males

Scrotal circumference• measure scrotal circumference all young bull at around 400d

- Scrotal circumference also contributes to DC EBV

- Early indicator of DC EBV for young bulls

Mating ability Fertility Performance of ancesters and daughters

Heritability of Fitness traits in females

Age at puberty 0.16 - 0.57

Age at first calving 0.06 - 0.19

Days to calving 0.08 - 0.11

Calving interval 0.01 - 0.06

Calving ease 0.09 - 0.13

Days open 0.09 - 0.20 Gestation length 0.15 Longevity 0.06 - 0.08 Stayability

0.03 - 0.11 Scortal circumference

0.40 - 0.46

Trait Production level h 2

BrahmanConception rate 0.77 0.11Pregnancy rate 0.76 0.11Calving rate 0.72 0.07Weaning rate 0.62 0.04Days to calving 0.22

Tropical CompositeConception rate 0.95 0.01Pregnancy rate 0.92 0.03Calving rate 0.90 0.03Weaning rate 0.78 0.03Days to calving 0.13

Heritabilities (h2) of reproductive traits of heifers (Johnston 2013)

Trait Lifetime annual calving rate

Lifetime annual weaning rate

Mating1Conception rate 0.61 0.41 Pregnancy rate 0.60 0.51 Calving rate 0.50 0.44 Days to calving -0.46 -0.54 Weaning rate 0.98 0.99 Mating 2Conception rate 0.90 0.76 Pregnancy rate 0.75 0.69 Calving rate 0.89 0.81 Days to calving -1.0* -0.96 Weaning rate 0.86 0.81Days to cycling -0.55 -0.60 Lactation anoestrous interval -0.71 0.62 Lactation cyclicity 0.59 0.53

Genetic correlations between early- and lifetime reproduction traits rate

Correlations show selection for reduced age at puberty will result in increased reproductive performance at both the early and lifetime stages.

Novelty traits for fertility

Male: Sperm quality Hormonal levels

Novelty traits: Males

LH – Luteinising hormone • Testosterone production • Influences onset of puberty

Inhibin • Regulation of sperm production

IGF-I – Insulin-Like Growth Factor-I • Growth stimulus • Bull SC and sperm motility and heifer puberty

Novelty traits: Males

Brahman Tropical Composite

Category Trait h2 h2

Inhibin 0.74 0.72

Hormone Luteinising Horm

0.31 0.48

Insulin-like GF 0.44 0.36

Mass Activity 0.24 0.13

Semen Quality Motility 0.15 0.15

18 months % Normal 0.25 0.20

.

Burns and Corbet 2012

Bull trait Age(Mths)

PregnancyRate

Calving Rate

Days to calving

HormonesInhibin 4 0.14 0.24 -0.13 Luteinising Hormone 4 -0.01 -0.20 0.51 IGF-I 6 0.29 -0.01 -0.11Semen QualityMass Activity 18 0.42 0.42 -0.38 Motility 24 0.34 0.32 -0.37%normal sperm 18 0.45 0.43 -0.50

24 0.26 0.50 -0.43Scrotal and sheathScrotal circumference 12 0.16 0.35 -0.36

18 0.14 0.24 -0.3424 0.14 0.25 -0.25

Sheath score 18 0.29 0.11 -0.12

Genetic correlations between bull traits and heifer reproduction

Bull trait Age(Mths)

L. Anoestrous interval

Calving Rate

Day to calving

HormonesInhibin 4 -0.08 0.14 -0.19Luteinising Hormone 4 -0.29 0.33 -0.29IGF-I 6 -0.21 0.20 -0.24Semen QualityMass Activity 18 -0.27 0.55 -0.24 Motility 24 -0.61 0.88 -0.84%normal sperm 18 -0.52 0.29 -0.21

24 -0.62 0.63 -0.69Scrotal and sheathScrotal circumference 12 -0.19 0.15 -0.19

18 -0.27 0.27 -0.3524 -0.09 0.10 -0.12

Sheath score 18 -0.12 0.11 -0.18

Genetic correlations between bull traits and 1st calf heifer reproduction

Novelty Traits: Males

No genetic antagonisms between semen quality and production traits

Scrotal and semen traits are genetically related to female age of puberty

Scrotal traits but especially semen traits related to reproductive output in cows

Requirements to implement novelty traits to improve beef production

Recognition of novel phenotypes associated with economically important traits

Determination if phenotype can be measured accurately

Assessment of variation associated with phenotype

Proportion of variation attributable to genetics

Programs to implement change

Birth Year

Number

Exposed

Number

Pregnant

% Pregna

nt

1998 77 6 7.79

1999 122 1 0.82

2000 122 16 13.11

2001 142 27 19.01

2002 159 86 54.09

2003 159 77 48.43

2004 149 77 51.68

2005 162 57 35.19

2006 113 81 71.68

2007 151 110 72.85

2008 141 103 73.05

2009 166 124 74.70

2010 177 138 77.97

Selection for early sexual maturity in Rancho da Matinha, ANCP Associate

(Lôbo et al. 2012)

Fertility and not growth is the most important trait in selection

Heifers should conceive first time and calf not later than 33 months

Each cow should calf each year (Herefords currently 384 days)

95% Strive to use Days to Calving – Mating

seasons compulsory DNA technology – Fertility markers

Traits h2 r Increase in accuracy

Progeny equivalents

Age at first calving 0.11 0.40 0.15 14

Heifer preg. Rate 0.24 0.32 0.07 6

Scrotal Circumference (12mth)

0.38 0.28 0.12 3

Stayability 0.12 0.38 0.11 9

Accumulated production

0.20 0.27 0.11 10

Change in BIF accuracy from the incorporation of

Pfizer molecular values into BLUP evaluation of young sires with no phenotypic information

(Lôbo et al. 2012)

Thanks