💡 Practical Examples

Real-world feeding scenarios and calculations for exam preparation

🐄 Example 1: Lactating Dairy Cow - Ration Design

▼

Problem Statement

A 600 kg Holstein dairy cow in early lactation is producing 35 liters of milk daily. Design a balanced ration using available forage and concentrates to meet her nutritional requirements.

Requirement Calculation

Daily dry matter intake target: 3-4% of body weight For 600 kg cow: 18-24 kg DM/day target Let's use 22 kg DM/day as target Energy requirement for 35 L/day milk: Maintenance NEL: ~15 Mcal/day Lactation NEL: 0.74 Mcal per L milk 35 L × 0.74 = 25.9 Mcal Total: 15 + 25.9 = 40.9 Mcal NEL/day Crude protein requirement: Maintenance: ~0.8 kg CP Milk production: ~1.0 kg CP (at 3.2% protein in milk) Total: ~1.8 kg CP minimum

Sample Ration Design (22 kg DM/day)

  • Alfalfa hay (good quality): 12 kg DM (50% forage minimum for rumen health)
  • Corn silage: 6 kg DM (moisture adjusted)
  • Dairy concentrate (high energy): 4 kg DM

Nutrient Analysis

Forage (hay + silage): 18 kg DM at 1.55 NEL = 27.9 Mcal Concentrate: 4 kg DM at 1.85 NEL = 7.4 Mcal Total NEL: 35.3 Mcal (still below 40.9 requirement) Adjustment needed: Increase concentrate to 6 kg DM New energy: 27.9 + (6 × 1.85) = 38.9 Mcal (closer but still slightly short) Better approach: 12 kg alfalfa + 4 kg silage + 6-7 kg high-energy concentrate This provides forage:concentrate ratio of 60:40 (appropriate for dairy) Crude protein: Alfalfa (18% CP): 12 × 0.18 = 2.16 kg CP Silage (8% CP): 4 × 0.08 = 0.32 kg CP Concentrate (16% CP): 6.5 × 0.16 = 1.04 kg CP Total: 3.52 kg CP (exceeds 1.8 kg requirement ✓)

Critical Management Points:

  • Maintain 50% forage minimum for rumen pH (prevent acidosis)
  • Calcium:phosphorus ratio 1.5-2.0:1 critical for milk production
  • Early lactation often shows negative energy balance (normal up to 4 weeks)
  • Ensure adequate fiber (NDF >28%) for rumen health
  • Monitor body condition - should not lose >1 BCS unit/month
  • Quality forage (alfalfa or good grass) supports both energy and protein

🐴 Example 1: Pregnant & Lactating Mare

▼

Problem Statement

A 500 kg Quarter Horse mare is in her 8th month of pregnancy. She previously required 2.2% of body weight in dry matter (11 kg DM) to maintain a body condition score of 5. Now you need to adjust her ration for late pregnancy.

Solution: Late Pregnancy Adjustment

Base requirement (previous maintenance): 2.2% BW = 11 kg DM/day Late pregnancy increase factor: +30-40% (3 months pre-parturition) Adjusted dry matter: 11 kg × 1.35 = ~14.8 kg DM/day Expected weight gain during late pregnancy: 0.45 kg/day Target total gestation gain: 60-80 kg (12-16% above baseline) Protein requirement: 7 g digestible CP per unit energy If ration provides 2.0 DE (energy units): Daily protein requirement: 2.0 × 7 = 14 g digestible CP minimum

Ration Composition

Design a 14.8 kg DM ration for late pregnant mare:

  • 10 kg good quality hay (1.4 DE, 7% CP)
  • 3 kg oats (1.3 DE, 10% CP)
  • 1.8 kg commercial concentrate (pelleted, 1.2 DE, 12% CP)

Nutrient Analysis

Energy (DE): (10×1.4) + (3×1.3) + (1.8×1.2) = 14 + 3.9 + 2.16 = 20.06 DE units Total dry matter: 10 + 3 + 1.8 = 14.8 kg ✓ Protein: (10×0.07) + (3×0.10) + (1.8×0.12) = 0.7 + 0.3 + 0.22 = 1.22 kg CP Protein:energy: 7 g digestible CP per DE unit ✓ Daily feeding schedule: - Hay: free access (or split 5-5 kg morning/evening) - Oats + concentrate: 2 kg × 2 feedings (morning + evening)

Key Points:

  • Mare should gain 0.45 kg/day (realistic target)
  • Minimum 50% forage (hay) = 7.4 kg, we're at 67% ✓
  • Avoid sudden diet changes; introduce concentrate gradually
  • Monitor body condition (target BCS 5-6 for late pregnancy)
  • After foaling, transition to lactation ration immediately

Post-Partum Transition (Peak Lactation)

At 3 weeks post-foaling, mare reaches peak lactation (10-18 L/day). Requirements increase further:

Peak lactation dry matter: 2-3% BW = 10-15 kg DM/day Protein requirement: 9 g digestible CP per unit energy (Higher than pregnancy due to milk production demands) Suggested modifications to ration: - Increase grain portion to 4-5 kg/day total - Consider adding high-quality forage (alfalfa 30% mix) - Ensure 2+ feeds daily minimum - Free water access at all times

🐔 Example 3: Broiler Chicken Production Phases

▼

Problem Statement

You are managing a broiler house with 10,000 birds targeting 2 kg live weight at 35-36 days. Calculate feed requirements and costs for each growth phase using phase feeding.

Phase Feeding Program

Phase Days Target BW (g) Crude Protein Feed Type
Starter 0-10 days 200-300 >20% High nutrient density
Grower 10-28 days 800-1200 20-22% Moderate density
Finisher 28-36 days 1700-2000 18-20% Lower protein, more energy

Feed Consumption Calculation

Assuming average FCR (Feed Conversion Ratio) = 1.8 kg feed per kg gain Target final weight: 2000 g per bird Total feed per bird: 2000 g × 1.8 = 3600 g (3.6 kg) For 10,000 birds: Total feed requirement: 10,000 × 3.6 kg = 36,000 kg (36 metric tons) Phase breakdown (approximation based on growth curve): - Starter (0-10d): ~400 g/bird = 4,000 kg total - Grower (10-28d): ~1,500 g/bird = 15,000 kg total - Finisher (28-36d): ~1,700 g/bird = 17,000 kg total

Daily Monitoring

Broiler production requires careful daily monitoring:

  • Daily weight sampling (50-100 birds minimum)
  • Calculate average daily gain (ADG) - target ~57 g/day for 2 kg at 35 days
  • Monitor feed intake and calculate FCR: FCR = cumulative feed ÷ cumulative live weight gain
  • Maintain target FCR ≤ 1.9 kg for economic viability
  • Track mortality (healthy flocks <3%)
  • Monitor house temperature and ventilation continuously

Critical Success Factors:

  • Phase feeding is essential - do NOT feed single diet for all 35 days
  • Starter phase: highest CP (>20%) supports rapid muscle development
  • Finisher phase: lower CP (18-20%) reduces costs while supporting final growth
  • Water quality and access equally important as feed quality
  • Litter management prevents disease and ammonia buildup
  • FCR >1.9 indicates problems: disease, poor feed quality, management issues

🐷 Example 4: Lactating Sow Nutrition & Piglet Management

▼

Problem Statement

A 250 kg sow has just given birth to 10 healthy piglets. Design a lactation feeding program and creep feed strategy for the piglets to ensure optimal weaning weight at 28 days.

Sow Lactation Requirements

Lactation duration: 30 days Daily feed intake (ad libitum): 5.8-6.6 kg/day Target maximum intake: 6.5 kg/day Ration specifications: - Crude protein: 16-18% - Minimum lysine: 0.9% - Crude fiber limit: 3-4% - Estimated daily energy: 1.0-1.2 DE per kg Peak lactation (day 21): - Milk production: 10-12 kg/day - This requires approximately 25-35% crude protein diet - At 6.5 kg feed: provides 6.5 × 0.30 = 1.95 kg CP minimum ✓

Sow Feed Formulation (Example)

  • Corn: 50% - primary energy source
  • Soybean meal: 15% - protein and lysine
  • Barley: 15% - energy, fiber balance
  • Tallow/fat: 5% - energy boost for lactation
  • Fish meal: 5% - high-quality protein, amino acids
  • Limestone: 2.5% - calcium for milk production
  • Premix (vitamins/minerals): 2.5% - micronutrient balance

Analysis: CP ~17%, Lys ~0.8-0.9%, suitable for lactation

Piglet Management Timeline

Age/Day Management Action Nutritional Management
Day 0 (Birth) Iron injection Dam colostrum 250-300 mL essential
Days 1-5 Maintain temp >33°C Nurse from dam; dam 4.8-5.5 kg/day feed
Days 7-10 Introduce creep feed High protein pellets; 4.3 kg dam milk per 1 kg piglet gain
Days 14-20 Increase creep access Target 150+ g creep feed daily
Days 21-28 Pre-weaning Target 200+ g creep/day; dam lactation peaks then declines
Day 28 Weaning Body weight target: ~8 kg/piglet

Creep Feed Formulation

Creep feed specifications (high quality, low fiber): - Crude protein: 18-22% - Crude fiber: <3% - Form: pellets (easier to consume for piglets) Example ingredients: Corn meal: 30% Soybean meal: 20% Skim milk powder: 10% Fish meal: 8% Barley: 20% Tallow: 5% Limestone + Premix: 7% This provides high CP (20%), high digestibility, attractive taste

Success Metrics:

  • Sow body condition: maintain good score throughout lactation
  • Piglet weight gain: ~200-250 g/day pre-weaning
  • Weaning weight target: 7-9 kg (influenced by colostrum intake, dam nutrition)
  • Creep feed intake pre-weaning: gradual increase from 7 days to 28 days
  • Minimize post-weaning mortality: creep feeding reduces stress at weaning
  • Sow weight loss during lactation should not exceed 15-20% of body weight

🐕 Example 5: Pregnant and Lactating Bitch Nutrition

▼

Problem Statement

A 30 kg female Labrador is in her final month of pregnancy with an estimated litter size of 8 puppies. Design a nutrition program for pregnancy and lactation, calculating DER (Daily Energy Requirements).

Energy Requirement Calculation

Step 1: Calculate RER (Resting Energy Requirements) RER formula: 70 × (Body Weight in kg)^0.75 RER = 70 × (30)^0.75 RER = 70 × 12.4 = 868 kcal/day Step 2: Calculate DER for pregnancy phases Exponent changes by trimester First 2 trimesters (pregnancy weeks 1-6): DER = Exponent × RER = 1.8 × 868 = 1,562 kcal/day (Maintenance level - no major increase yet) Final trimester (pregnancy weeks 7-9): DER = Exponent × RER = 2.5 × 868 = 2,170 kcal/day (Assuming moderate litter size, 25-50% increase) Peak lactation (3-4 weeks post-parturition): DER = Exponent × RER = 4.0 × 868 = 3,472 kcal/day (Most demanding physiological state = 4× maintenance)

Pregnancy Nutrition Plan

Weeks 1-6 (Maintenance Level)

  • Daily intake: Normal maintenance diet (~1,562 kcal/day)
  • Feed quality: High-quality commercial diet (AAFCO complete & balanced)
  • Crude protein: 18-22%
  • Fat: 8-15%
  • Quantity: Feed to maintain body condition 4-5/9

Weeks 7-9 (Final Trimester)

  • Daily intake: Increase to 2,170 kcal/day (+40% above early pregnancy)
  • Feeding frequency: 3 meals per day (smaller portions easier to digest)
  • Crude protein: 22-23%
  • Fat: 10-25% (supports fetal development)
  • Monitor body condition: avoid excessive weight gain (target +25-50% of pre-breeding weight)

Lactation Nutrition Plan

Weeks 1-2 (Early lactation): DER = 2.5 × 868 = 2,170 kcal/day Weeks 3-4 (Peak lactation): DER = 4.0 × 868 = 3,472 kcal/day (Increase from pregnancy 2,170 → lactation 3,472 = +60% increase) Weeks 5-7 (Late lactation, declining): DER = 3.0 × 868 = 2,604 kcal/day (Gradual reduction as puppies become more independent)

Sample Lactation Diet

At peak lactation, bitch requires ~3,472 kcal/day:

  • Option 1: High-quality commercial lactation diet (25-35% CP, >18% fat) + ad libitum feeding
  • Option 2: Standard diet + supplemental protein/fat
  • Example feed plan: 2.5 cups high-quality kibble × 4 feedings = ~3,500 kcal (verify kcal/cup on package)

Puppy Colostrum & Weaning

Stage Age Nutrition/Management
Colostrum Birth-12h 10% Ig; 12-24h absorption window critical
Nursing 12h-3 weeks Milk only; bitch needs high nutrition (see above)
Semisolid intro 3 weeks Moistened high-protein puppy food 3-4 times/day
Weaning 5-7 weeks Transition to solid food; dry:water = 2:1 at 5-6 weeks
Completed weaning 6-8 weeks 100% solid food; high-quality puppy diet (>25% CP)

Critical Success Factors:

  • Peak lactation is most demanding - can lose 20-30% body weight if underfed
  • DER increases 4× from maintenance during peak lactation
  • Ad libitum (unlimited) feeding during lactation recommended
  • Monitor bitch body condition weekly (target 4-5/9 score)
  • Colostrum absorption window only 12-24 hours - critical for passive immunity
  • Puppies reaching 50% adult weight by 4 months (for <25 kg adult dogs)

🐰 Example 6: Lactating Rabbit Doe and Kit Growth

▼

Problem Statement

A New Zealand white doe (3.5 kg) has delivered 8 kits. Design a feeding program for peak lactation and create a growth plan for meat broiler production to market weight (2.5 kg) at 10-12 weeks.

Lactating Doe Nutrition

Gestation: 31 days (already completed) Lactation: 5-6 weeks (most demanding stage) Peak lactation: day 21 post-parturition Doe milk characteristics: - DM content: 30-34% (extremely concentrated) - Fat: 15-17% - Protein: 11.5-13% - 8 kits × nursing = high demand Nutritional requirements: - Crude protein: 17-18% for maximum milk production - Digestible energy: High-quality feeds (alfalfa hay, grains) - Feed intake: Ad libitum (unlimited access) - Hay: Essential for fiber and digestive health

Doe Feeding Plan (Peak Lactation)

  • Timothy hay or alfalfa: Ad libitum (free access)
  • Grain mixture: 75-100 g/day (oats and barley mix)
  • Pellets (commercial): 100-125 g/day (17-18% CP)
  • Water: Fresh, clean, unlimited access
  • Feeding frequency: Once or twice daily

Analysis: This ration provides adequate energy and 18%+ protein for sustaining peak lactation of concentrated rabbit milk.

Kit Growth Timeline & Weight Targets

Age (days) Nutrition Source Target Weight Notes
0-19 Doe milk only ~80-150 g Dependent on doe
19-28 Milk + creep feed intro 200-350 g Begin solid food transition
28-35 (Weaning) Growing solid diet 400-600 g Separation from doe
35-60 Growing diet continued 1200-1800 g 30-38 g ADG
60-84 (Market) Growing diet 2300-2500 g Ready for processing

Kit Feeding Plan (Post-Weaning)

Growing diet composition (weaning to market weight):

  • Timothy hay: Ad libitum (essential fiber, prevents enteritis)
  • Oats: 50% of grain portion (digestible, safe)
  • Barley: 30% of grain portion
  • Pellets (17% CP): 10-20 g/day → 40-60 g/day (increasing with age)
  • Total grain: ~50-80 g/day increasing toward market
  • Critical: Cannot overfeed concentrate - high energy causes enteritis in rabbits

Growth Performance Calculation

Weaning weight (28 days): 400 g average Market weight (84 days): 2500 g Total weight gain: 2100 g over 56 days (days 28-84) Average Daily Gain (ADG): 2100 g ÷ 56 days = 37.5 g/day ✓ Feed intake estimate: Total gain: 2.1 kg FCR (Feed Conversion Ratio): 2.5-3.2 kg Total feed needed: 2.1 × 2.8 = 5.9 kg This includes: - Hay (ad libitum): ~3.2 kg - Grain & pellets: ~2.7 kg Production metrics: - 8 kits × 2.5 kg market weight = 20 kg live weight per doe per cycle - 2 production cycles per year possible - Doe productivity: 40 kg meat/year

Management Recommendations:

  • Doe milk is most concentrated of all mammals (30-34% DM) - kits grow rapidly
  • FCR of 2.5-3.2 kg is excellent compared to other species
  • Cecotrophy critical for kit health - high-quality hay essential
  • Fiber prevents enteritis - never feed excessive grain or pellets
  • Fresh water available at all times
  • Monitor for signs of digestive upset (wet cecotrophs, diarrhea)
  • Keep litter clean and dry
← Back to Home