laboratory introduction fall 2011...a study: pullets have an appetite for calcium (classen and...
TRANSCRIPT
Dinesh Kumar (M.Sc. Candidate)
Dept. of Animal and Poultry Science
University of Saskatchewan
1
Introduction
Genetic improvement of laying hens
Increased egg production
Improved egg quality
Reduced hen weight
Feed intake
Feed efficiency
Early sexual maturity
2
Introduction contd.
Nutritional management Rearing period (growth)
Laying period (egg performance)
Importance of calcium Skeletal development during rearing
(Whitehead and Fleming, 2000)
Improves eggshell quality during lay (Safaa et al., 2008)
Protein Requirement For growth and egg production
3
Pullet Feeding Program (Lohmann-LSL Lite)
Diet
Age (wk) % CP % Lys % Ca % Av PME
(Kcal/kg)
Developer 9 - 16 15.0 0.70 0.95 0.37 2800
Pre-Lay 16 - 18 17.0 0.85 2.5 0.45 2800
Pre-Peak18 – 50%
EP19.0 0.90 4.0 0.65 2800
4
Pullet Feeding Program (Lohmann-LSL Lite)
Diet
Age (wk) % CP % Lys % Ca % Av PME
(Kcal/kg)
Developer 9 - 16 15.0 0.70 0.95 0.37 2800
Pre-Lay 16 - 18 17.0 0.85 2.5 0.45 2800
Pre-Peak18 – 50%
EP19.0 0.90 4.0 0.65 2800
5
Pullet Feeding Program (Lohmann-LSL Lite)
Diet
Age (wk) % CP % Lys % Ca % Av PME
(Kcal/kg)
Developer 9 - 16 15.0 0.70 0.95 0.37 2800
Pre-Lay 16 - 18 17.0 0.85 2.5 0.45 2800
Pre-Peak18 – 50%
EP19.0 0.90 4.0 0.65 2800
6
Calcium utilization in laying hens
Need for Ca for eggshell synthesis
Dietary calcium is not sufficient
Additional Ca is drawn from medullary bone
Department of Animal and Poultry Science 7
Cortical and medullary bone development
8
Cortical and medullary bone development
9
Source: www.Wikipedia.org
Cortical or Cancellous Bone: Outer bone layer, hard and compact Provides smooth, solid, white appearance
Bone Development
Source: www.wikipedia.org 10
Medullary bone formation
11
Long bones elongate with growth of chondrocytes
Chondrocytes replaced by osteoblasts to form structural trabecular bone
Cortical bone formation with bone reabsorption by osteoclasts
Estrogen changes the function of osteoblasts to form medullary bone
12
Endocrine effects of photostimulation
Development of
characteristics
essential for
reproduction
13
Ovary and follicle types
Note follicle pulled from ovary
and nature of tissues layers
surrounding ovum
Follicular hierarchy (upper)
Small yellow, large white and
small white follicles (lower)
Internal cavity of a long bone from a non-laying chicken (a)
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Cortical
bone
Trabecular
bone
Medullary
bone
Internal cavity of a long bone filled with medullary bone in a laying hen (b)
When does medullary bone develop?
Two to three weeks before the start of lay (Hurwitz, 1964)
Pullets increase calcium intake on average 19 days before laying their first egg (Classen and Scott, 1982)
Consumed 2.08% of their total diet intake as calcium
Research validates feeding higher calcium prior to the onset of lay (pre-lay diet)
Recommended level – 2.0 to 2.5%15
What if Ca level is as low as in rearing diets?
16
What if Ca level is as low as in rearing diets?
Weak bones
Cage layer fatigue
Osteoporosis
17
What if Ca level is as low as in rearing diets? Weak bones /
osteoporosis
Cage layer fatigue
Reduced eggshell quality
18
What if Ca level is as low as in rearing diets? Weak bones /
osteoporosis
Cage layer fatigue
Reduced eggshell quality
A pre-lay diet is an insurance policy against Ca deficiency during lay
19
What if pre-lay Ca levels are too high or are fed too long?
Department of Animal and Poultry Science 20
What if pre-lay Ca levels are too high or are fed too long?
Problem of urolithiasis
Kidney stones
21Kidney stone
Urolithiasis (Kidney stones)
Kidney stones are frequently seen in pullets and caged layers (Jones et al. 1978)
High Ca fed during pullet growing period may cause Urolithiasis (Wideman et al., 1985)
Higher available P can ameliorate the effect of excessive Ca in the rearing diet
Higher Ca and low available P is not a favourable combination
22
A study on Urolithiasis (Wideman et al., 1985)
4 x Treatment diets
1. Normal Ca (1.0%) and normal P (0.6) – NCNP (Control)
2. High Ca (3.25%) and normal P (0.6%) – HCNP
3. Normal Ca (1.0%) and low P (0.4%) – NCLP
4. High Ca (3.25%) and low P (0.4%) - HCLP
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Results: No. of cases with kidney stones (%)
24
2%
14%
3%
Why higher protein in a Pre-lay diet?
25
Pullet Feeding Program (Lohmann-LSL Lite)
Diet
Age (wk) % CP % Lys % Ca % Av PME
(Kcal/kg)
Developer 9 - 16 15.0 0.70 0.95 0.37 2800
Pre-Lay 16 - 18 17.0 0.85 2.5 0.45 2800
Pre-Peak18 – 50%
EP19.0 0.90 4.0 0.65 2800
26
Pullet body weight chart (g)
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Pullet weight chart (g)
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0
200
400
600
800
1000
1200
1400
1600
1800
1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930
Age (weeks)
Pre-Lay Period
Pullet weekly body weight gain (g)
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Pullet weekly body weight gain (g)
30
Extra protein needed for
Development of organs involved in egg production
Ovaries
Oviduct
Liver
Inadequate protein
Reduced pullet weight gain or if extreme weight loss
Effect on egg performance
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Why protein level in a Pre-lay diet is lower than Pre-peak diet (layer diet 1)?
Pre-lay diet: 17.0% CP
Pre-peak diet: 19.0% (layer diet 1)
Reasons
None or only 1-2% of egg production
Feed cost, wet litter, ammonia pollution
32
Things to think about
Using a pre-lay diet to compensate for low pullet weight?
Should we be assessing daily feed intake to establish diet nutrient levels?
33
A Pre-Lay Diet: An overview
Feeding Period (7 – 14 days) Between 16 – 18 weeks of age
First egg – 1 to 2% of egg production
Pullet wt, sexual maturity and flock uniformity
Higher dietary calcium (2.0 - 2.5%) Medullary bone development
Increased dietary protein level (17%) Liver and sexual organs growth and muscling
34
Pre-lay Feeding Programs
Pullets
Age (wk) % CP % Lys % Ca % Av PME
(Kcal/kg)
Hy-line 15 - 17 16.5 0.72 2.5 0.48 2900
Lohmann-LSL 16 - 18 17.0 0.85 2.5 0.45 2800
Bovans (Br)16 – 2%
EP16.8 0.80 2.0 0.42 2750
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Take home message
Birds have an appetite for calcium prior to lay
Higher calcium in pre-lay diets is needed for development of medullary bone
Slightly higher protein to facilitate sexual growth
Normal level of available phosphorus
Hen weight and flock uniformity are key factors to decide the length of pre-lay feeding
Pullet body weight and sexual maturity should be carefully monitored during pre-lay period
36
Take home message
Higher calcium in pre-lay diets is needed for development of medullary bone
Higher protein to facilitate sexual development
Hen weight and flock uniformity are key factors to decide the length of pre-lay feeding
Pullet body weight and sexual maturity should be carefully monitored during pre-lay period
38
Calcium level in a Pre-lay diet
What if Ca level is as high as in layer diets
( ̴ 4%)?
What if Ca level is as low as in rearing diets (<1%)?
If Ca level is high:
Problem of Urolithiasis (kidney stones)
If Ca is low:
Weaker bones/osteoporosis, eggshell quality39
A study: Pullets have an appetite for Calcium(Classen and Scott, 1982)
Exp. 1: 2 x diets, fed 5 to 18 weeks
Diet 1 (control ration): 0.89% Calcium and 0.46% avail. Phosphorus
Diet 2 (calcium self-selection ration): Control ration without the inclusion of ground
limestone (0.35% calcium) and was fed in combination with a separate source of chick-sized double duty grit (38% calcium).
Result: Ca consumption was significantly higher (1.18%) in Ca self-selection ration compared to control ration (0.89%)
40
Exp. 2 (Classen and Scott, 1982)
Exp. 2: 3 x layer diets, fed 25 to 32 weeks
Diet 1 (control ration):
3.50% Calcium and 0.36% avail. Phosphorus
Diet 2 (Oyster shell ration):
Control ration with ground limestone replaced with equal amount of oyster shell (38% calcium)
Diet 3 (calcium self-selection ration):
Control ration without the inclusion of ground limestone (0.35% calcium) and was fed in combination with a separate source of chick-sized double duty grit (38% calcium). 41
Results: Exp. 2 (Classen and Scott, 1982)
Results (25 to 32 weeks):
Calcium intake for calcium self-selection pullets was significantly higher (1.92%) than control (0.98%)
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