Current Advances in Broiler Breeder Modeling Research: a North American Perspective Martin J. Zuidhof 1 R. A. Renema, and A. Pishnamazi AMEVEA Bogotá, Colombia April 18-19,

1957 broiler1977 broiler2005 broiler Why are Broiler Breeders Difficult to Manage?

The Nutritionist’s Goal Match nutrient supply to nutrient requirements The Organism’s Goal To feel good and be productive Feel good = f(eat, not eat…) Feel good = f(health, fitness, environment, luxury, scarcity,…)

UnderfedOverfed

Breeder:Broiler BW ratio* from 1979 to 2005 Renema et al WPSJ 63: *6 wk of age

Uniformity Issue: Competing for a limited resource Photo courtesy Philippe Dufour, Cobb-Vantress Broiler breeder feeding time - Brazil

Experimental Design 9

10 SourceProbability Treatment< Age Tmt x Age< Sorting Scatter Sorting and Scatter Feeding Increased Uniformity b c a

Summary – Uniformity Trial Sorting was best for uniformity – Practical consideration: help the smallest group by segregating and giving extra feed Scatter feeding and skip-a-day feeding also improved flock uniformity at photostimulation Skip-a-day feeding – increased fat stores – reduced breast muscle weight and average egg weight presumably due to metabolic inefficiencies 11

Feed Management Composition / Formulation Are current recommendations for protein levels too high? Current research Composition restriction: A new paradigm in broiler breeder feeding

Feed Management Feed Allocation Change feed allocations gradually – Consider the bird’s metabolism (Requirements change gradually) – How are nutrient requirements changing? Goal: Match nutrient supply to nutrient requirements 13 Don’t let the bird’s metabolism know that you’ve changed the feed allocation -- Frank Robinson

Feed Allocation Principles Use BW gain as an indicator of metabolic status Weigh frequently Take the weather into consideration

RECENT RESEARCH Manipulating Reproductive Potential: Growth Profile and Photostimulation Age

Experimental Design 3 commercial strains 4 body weight targets 2 photostimulation ages – 18 wk – 22 wk

Growth Curve Targets STANDARD: Mean target BW profile

Growth Curve Targets LOW: 12 wk BW = 75% of STANDARD Rapid rate of gain to 32 wk

Growth Curve Targets MODERATE: 12 wk BW = 150% of STANDARD Lower rate of gain to 32 wk

Growth Curve Targets HIGH: 12 wk BW = 200% of STANDARD Minimal rate of gain to 32 wk

Age at First Egg P-values: Strain=0.29 Feed= PS age< c bc b a

Total Egg Production* *to 58 wk of age

Photostimulation: Early = More Eggs

Photostimulation: Later = More Settable Eggs

So What? We may have more flexibility than we sometimes think when manipulating growth curves

When broiler breeders start to lay, they are highly motivated to repartition nutrients away from growth, and toward egg production.

RECENT MODELING RESEARCH Effect of environmental temperature on maintenance energy requirements of broiler breeders

Core Body Temperature Dynamics

Feed Allocation Principles Use BW gain as an indicator of metabolic status Weigh frequently Take the weather into consideration

Pullets: Nutrient Requirement Model Account for – Body weight (W) – Temperature (T) – Gain (G) – Age (A) MEI = A(W 0.67 ) (W 0.67 )(T e - 21) G

“Maintenance Energy” Model Age related effects (age=x) ME m = x x x E-06x 4 Why?

Comparing Results

Partitioning of 55 g of Feed* (2,750 kcal/kg) *1.3 kg pullet

Gain per 55 g of Feed (2,750 kcal/kg) *1.3 kg pullet *assuming requirement for gain of kcal/g

Hens: Nutrient Requirement Model Account for – Body weight (W) – Environmental temperature effect on maintenance (W x T) Linear Quadratic – Gain (G) – Egg production (E) MEI = 213.5W W 0.68 (T e ) W 0.68 (T e 2 ) G +1.12E maintenanceEgg Linear nonlinear Effect of Temperature on maintenance Gain

Nonlinear Effect of T on ME Requirement Predicted daily ME intake for a 3 kg bird gaining 10 g/d, producing 50 g of egg mass per day, on average Growth (30 g/d difference) Growth

Decreasing Post-peak Feed Allocations Keep birds growing on target Birds in a positive energy balance will prioritize nutrients toward egg production 39

Match nutrient supply to nutrient requirements Feed allocation: nutrient requirements change slowly… Make feed increases as small and as frequent as possible Use BW GAIN for feed allocation decisions Principles of Breeder Management Utilizar la GANANCIA DE PESO de las decisiones de asignacion de alimentacion

Stimulate sexual maturity by changing daylength (not feed) Support the necessary body weight gain needed with feed EGGS WILL FOLLOW – they are a hen’s priority Principles of Breeder Management

Don’t let the bird’s metabolism know that you have changed the feed allocation Principles of Breeder Management

Don’t forget…… you are managing something you can’t see! you are managing something you can’t see!

THE FUTURE Precision management of individual broiler breeders

Managing Individual Hens Providing the right amount of feed to the right bird at the right time BW Under target Small meal Target or higher Eject from station

Breeder Management Top 10 1.Know the actual weight of your birds 2.Weigh the birds at the same time each day 3.Flock uniformity is very, very important 4.Avoid high nutrient density diets 5.Make sure pullets are at the minimum threshold BW at lighting 6.Don’t make fast increases in feed intake coming into production Robinson, 1996

Breeder Management Top 10 7.Know what you are doing in managing post-peak feed withdrawal 8.Keep an open mind – birds are changing every year (what worked the last flock may not work this year) 9.Don’t put your flock on ‘AUTO-PILOT’ 10.Stay positive person and keep learning 11.Manage birds according to body weight gain instead of BW Adapted, Robinson, 1996

How the Benefit Will Be Gained Stable metabolism Efficiency Flock uniformity – Egg production – Fertility

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