Dairy and Poultry Production

What to remember

• Milk is a complete food with about 87 % water; its main sugar is lactose and its main protein is casein. Cow milk has about 4 % fat, buffalo milk about 6 to 7 % fat. Pasteurisation (63 °C for 30 minutes, or 72 °C for 15 seconds) kills disease germs.
• Poultry: chicken eggs hatch in 21 days at about 37.5 °C; layers are White Leghorn types and broilers are fast-growing meat strains reaching market weight in about 6 to 7 weeks.
• Feed conversion ratio (FCR) = feed eaten / weight gained (or eggs produced). A lower value means better efficiency.

Milk: composition, quality and testing

• Total solids = fat + SNF. SNF includes lactose, proteins, minerals and vitamins.
• Proteins: casein (about 80 % of milk protein; precipitates at pH 4.6 and with rennet) and whey proteins (lactalbumin, lactoglobulin).
• Fat is present as small globules and gives the cream. Buffalo milk is whiter because it has no carotene (cow milk has a yellow tint).
• Specific gravity of normal cow milk is about 1.028 to 1.032, measured with a lactometer at 15.5 °C (60 °F). Adding water lowers it; removing cream raises it.
• pH of fresh milk is about 6.6 to 6.8. Acidity is expressed as per cent lactic acid (about 0.13 to 0.15 % in fresh milk).
• Colostrum is the first milk after calving; it is rich in antibodies (immunoglobulins), vitamin A and protein. It should be fed to the calf and not sold.
• Tests: Gerber method for fat (using sulphuric acid and amyl alcohol, centrifuge); lactometer for adulteration with water; alcohol test and clot-on-boiling test for acidity; methylene blue reduction test (MBRT) and resazurin test for keeping quality (bacterial load); phosphatase test to confirm that pasteurisation was done properly (a negative test means correctly pasteurised); California Mastitis Test for udder infection.
• Standard milk types (typical): full cream, standardised, toned (3 % fat), double toned (1.5 % fat), skimmed (very low fat). Toned milk is made by adding skim milk powder and water to buffalo milk.

Milking, lactation and dairy management

• Lactation curve: yield rises for about 4 to 6 weeks after calving, peaks, then falls slowly. A standard lactation is 305 days, followed by a dry period of about 60 days.
• Calving interval target: 12 to 13 months. Age at first calving: 30 to 36 months for crossbreds.
• Milk let-down is caused by the hormone oxytocin (posterior pituitary), triggered by washing the udder, the calf's presence or the milking routine. Adrenaline blocks let-down, so avoid noise and fear. Prolactin supports milk synthesis.
• Milking methods: full-hand (best, whole hand), stripping and knuckling (bad, hurts the teats); machine milking in big dairies.
• Clean milk production: healthy cow, clean shed, wash and dry udder with warm antiseptic water, clean milker with trimmed nails, stainless steel or aluminium clean utensils with narrow mouth, filter milk, cool quickly to below 5 °C, avoid delay. Discard the first jets of milk (foremilk).
• Mastitis is the commonest and costliest disease of dairy animals. It is inflammation of the udder, with a change in milk and the udder. Teat dipping after each milking reduces it.
• Housing: sheds should be dry, ventilated and shaded; floor slope 1 in 40; separate calf pen. Fresh water always.

Dairy products and processing

Pasteurisation heats milk to destroy disease-causing germs without much change in taste or nutrition.

• After pasteurisation milk is cooled quickly to below 5 °C. Homogenisation breaks fat globules so cream does not rise.
• Cream separator works by centrifugal force. Cream has 25 to 40 % fat. Butter has at least 80 % fat and about 16 % moisture; made by churning ripened cream. Ghee (clarified butter fat) has about 99.5 % fat and almost no moisture. Skim milk powder and whole milk powder are made by spray drying.
• Curd (dahi) is made by lactic acid bacteria (Lactococcus, Lactobacillus) which turn lactose into lactic acid. Paneer is acid-coagulated milk, pressed. Cheese is made with rennet (enzyme) from milk casein, then ripened. Khoa is milk evaporated until semi-solid.
• Lactose intolerance is due to lack of the enzyme lactase.
• Cooperatives: AMUL (Anand, 1946) showed the model. Operation Flood (1970), also called the White Revolution, was run by the National Dairy Development Board (NDDB). Verghese Kurien is known as the father of the White Revolution. In AP, milk is collected by village cooperatives and sold under well-known cooperative brands, including Vijaya (the state dairy federation).

Poultry: breeds, housing and production

• Types: layers (egg), broilers (meat) and dual-purpose (backyard) birds. Common layer strains are White Leghorn crosses; broilers are fast-growing hybrids (such as Cobb and Ross). Duck breeds: Khaki Campbell (best egg layer), Indian Runner.
• Systems: free range, semi-intensive, deep litter (a layer of dry husk or straw 5 to 8 cm deep, stirred regularly) and cage (battery) system. Cage layers are hygienic but costly.
• Brooding: chicks need heat for the first weeks. Start at about 35 °C (95 °F) under the brooder in week 1 and reduce by about 3 °C each week (5 °F). Signs: chicks spread evenly when comfortable; crowd under the heat when cold; move away when hot.
• Lighting: laying hens need about 16 hours of light per day (natural plus artificial); a falling day length reduces laying.
• Growth stages: chick (0 to 8 weeks), grower (8 to 18 or 20 weeks), layer (from point of lay at about 18 to 20 weeks; peak at about 28 to 30 weeks; first laying cycle about 72 weeks). Broiler marketed at about 6 to 7 weeks and 2 kg or more.
• Feeds: chick mash (high protein, about 20 %), grower mash (about 16 %), layer mash (about 16 to 18 % protein with extra calcium for the shell, with oyster shell or limestone grit), broiler starter (about 22 to 23 %) and finisher. Maize is the main energy source; soybean meal the main protein source.
• Debeaking (beak trimming) prevents cannibalism and feather pecking.

Eggs and incubation

• Egg composition: shell about 11 %, albumen (white) about 58 % and yolk about 31 %. Shell is mainly calcium carbonate. A fresh egg has a small air cell.
• Incubation period: chicken 21 days; duck 28 days; turkey 28 days; Japanese quail about 17 to 18 days; goose about 30 days.
• Incubator conditions: temperature about 37.5 °C (99.5 °F), relative humidity about 55 to 60 % for setting and about 65 to 70 % for the last 3 days (hatching), turning of eggs several times a day up to day 18, then no turning.
• Candling is done to check fertility (first on about day 7 and next on about day 14 or 18). Fertile eggs show a network of blood vessels; infertile eggs stay clear; dead embryos show a blood ring.
• Egg storage before setting: 10 to 15 °C; set within about 7 days. Eggs are kept with the pointed end down and set tray turned.
• Hatchability = chicks hatched / fertile eggs set x 100. Fertility = fertile eggs / total eggs set x 100.
• Egg quality traits: shell strength, albumen height (Haugh unit), yolk colour, and no blood or meat spots.
• Hen-day egg production = total eggs / (number of hens x number of days) x 100.
• Feed conversion ratio for broilers is about 1.7 to 2.0 in modern strains; the value is 1.7 if 1.7 kg feed is eaten to give 1 kg of live weight.

Worked examples

• 1. A cow gives 10 kg milk with 4 % fat. Fat yield = 10 x 0.04 = 0.4 kg.
• 2. Pearson square for fat standardisation: to make toned milk of 3 % fat from buffalo milk (6 %) and skim milk (0.05 %, taken as 0): parts of buffalo milk = 3 - 0 = 3; parts of skim milk = 6 - 3 = 3. Ratio 1 : 1, so 50 litres of each gives 100 litres.
• 3. A flock of 200 hens laid 150 eggs in a day. Hen-day production = 150 / 200 x 100 = 75 %.
• 4. A broiler ate 3.6 kg feed and weighed 2 kg. FCR = 3.6 / 2 = 1.8.
• 5. 1,000 eggs set; 900 fertile; 720 chicks hatched. Fertility = 90 %; hatchability of fertile eggs = 720 / 900 x 100 = 80 %.
• 6. 100 kg of cream containing 40 % fat is churned to make butter with 80 % fat. Fat in cream = 40 kg; butter weight ≈ 40 / 0.80 = 50 kg (ignoring loss).
• 7. Chicken eggs set on 1 January (non-leap year) will hatch on 22 January (21 days).

Exam traps

• Casein vs whey proteins: casein is the main protein and clots with rennet or acid.
• LTLT vs HTST: 63 °C for 30 minutes versus 72 °C for 15 seconds.
• Pasteurisation vs sterilisation vs UHT: only sterilisation and UHT give long shelf life without refrigeration; pasteurised milk needs cold storage.
• Phosphatase test vs MBRT: phosphatase checks pasteurisation; MBRT checks bacterial quality.
• Butter vs ghee: butter is about 80 % fat with water; ghee is about 99.5 % fat.
• Fertility vs hatchability: based on total eggs versus fertile eggs.
• Incubation: chicken 21 days, duck 28 days, quail 17 to 18 days.
• Oxytocin vs prolactin: oxytocin causes milk let-down; prolactin is for milk production.

One-liners

• 1. Casein is about 80 % of milk protein.
• 2. Lactose is the sugar of milk.
• 3. Cow milk fat is about 4 %; buffalo about 6 to 7 %.
• 4. HTST pasteurisation is 72 °C for 15 seconds.
• 5. LTLT pasteurisation is 63 °C for 30 minutes.
• 6. A negative phosphatase test shows proper pasteurisation.
• 7. Oxytocin triggers milk let-down.
• 8. Standard lactation is 305 days with a 60-day dry period.
• 9. Operation Flood was run by NDDB; Verghese Kurien led it.
• 10. Chicken eggs hatch in 21 days.
• 11. Hen-day production = eggs / (hens x days) x 100.
• 12. Khaki Campbell is the best egg-laying duck breed.

Practice questions

1. The main protein of milk is:

   1. globulin
   2. keratin
   3. casein
   4. albumin
   Answer

   C. casein

   Casein forms about 80 % of milk protein.

2. The main sugar of milk is:

   1. fructose
   2. sucrose
   3. maltose
   4. lactose
   Answer

   D. lactose

   Lactose is the milk sugar.

3. The first milk after calving, rich in antibodies, is called:

   1. buttermilk
   2. colostrum
   3. whey
   4. skim milk
   Answer

   B. colostrum

   Colostrum gives passive immunity to the calf.

4. The hormone responsible for milk let-down is:

   1. thyroxine
   2. oxytocin
   3. insulin
   4. progesterone
   Answer

   B. oxytocin

   Oxytocin from the posterior pituitary causes the udder to eject milk.

5. HTST pasteurisation of milk uses:

   1. 100 °C for 1 minute
   2. 72 °C for 30 minutes
   3. 72 °C for 15 seconds
   4. 63 °C for 15 seconds
   Answer

   C. 72 °C for 15 seconds

   HTST is 72 °C for 15 s; LTLT is 63 °C for 30 min.

6. LTLT (holding) pasteurisation uses:

   1. 72 °C for 15 seconds
   2. 135 °C for 2 seconds
   3. 90 °C for 1 hour
   4. 63 °C for 30 minutes
   Answer

   D. 63 °C for 30 minutes

   Holding method is 63 °C for 30 minutes.

7. Chicken eggs hatch in about:

   1. 28 days
   2. 18 days
   3. 21 days
   4. 35 days
   Answer

   C. 21 days

   The incubation period of chicken is 21 days.

8. The incubation period of duck eggs is:

   1. 18 days
   2. 35 days
   3. 21 days
   4. 28 days
   Answer

   D. 28 days

   Duck and turkey eggs need 28 days.

9. The standard length of a lactation is:

   1. 200 days
   2. 305 days
   3. 365 days
   4. 120 days
   Answer

   B. 305 days

   A standard lactation is 305 days.

10. The best egg-laying duck breed is:

    1. Muscovy
    2. Pekin
    3. Khaki Campbell
    4. Aylesbury
    Answer

    C. Khaki Campbell

    Khaki Campbell lays many eggs a year.

11. Ghee contains about ____ milk fat.

    1. 60 %
    2. 40 %
    3. 80 %
    4. 99.5 %
    Answer

    D. 99.5 %

    Ghee is nearly pure fat.

12. Operation Flood was implemented by:

    1. NDDB
    2. ICAR
    3. FSSAI
    4. NABARD
    Answer

    A. NDDB

    The National Dairy Development Board led the White Revolution.

13. The father of the White Revolution in India is:

    1. B. P. Pal
    2. Verghese Kurien
    3. M. S. Swaminathan
    4. Norman Borlaug
    Answer

    B. Verghese Kurien

    Kurien led NDDB and Operation Flood.

14. The test used to check that milk was properly pasteurised is the:

    1. alcohol test
    2. lactometer test
    3. Gerber test
    4. phosphatase test
    Answer

    D. phosphatase test

    Alkaline phosphatase is destroyed by correct pasteurisation.

15. Methylene blue reduction test (MBRT) is used to assess:

    1. adulteration by water
    2. bacterial quality of milk
    3. fat content
    4. protein content
    Answer

    B. bacterial quality of milk

    Quicker decolourisation means more bacteria.

16. The Gerber method is used to determine the ____ of milk.

    1. fat
    2. protein
    3. lactose
    4. ash
    Answer

    A. fat

    Gerber uses sulphuric acid and amyl alcohol with a centrifuge.

17. A lactometer reading that falls below normal suggests:

    1. dehydration of the cow
    2. added cream
    3. added water
    4. a higher fat test
    Answer

    C. added water

    Adding water lowers the specific gravity.

18. Buffalo milk is whiter than cow milk because it lacks:

    1. lactose
    2. calcium
    3. carotene
    4. casein
    Answer

    C. carotene

    Buffalo convert carotene to vitamin A in the body.

19. Butter must contain at least ____ milk fat.

    1. 20 %
    2. 80 %
    3. 99 %
    4. 50 %
    Answer

    B. 80 %

    Butter has at least 80 % fat.

20. Curd is formed by the action of:

    1. lactic acid bacteria on lactose
    2. moulds on protein
    3. yeast on fat
    4. rennet on lactose
    Answer

    A. lactic acid bacteria on lactose

    Lactic acid bacteria make lactic acid, which sets the milk.

21. The enzyme used to make cheese from milk is:

    1. lactase
    2. rennet
    3. amylase
    4. pepsin of the pig only
    Answer

    B. rennet

    Rennet (chymosin) coagulates casein.

22. Chicken eggs in an incubator are usually kept at about:

    1. 30 °C
    2. 42 °C
    3. 25 °C
    4. 37.5 °C
    Answer

    D. 37.5 °C

    The standard incubator temperature is 37.5 °C (99.5 °F).

23. The first candling of hatching eggs is usually done on about day:

    1. 1
    2. 20
    3. 7
    4. 21
    Answer

    C. 7

    Fertile eggs show blood vessels by day 7.

24. Laying hens need about ____ hours of light per day.

    1. 6
    2. 10
    3. 24 hours with no dark period
    4. 16
    Answer

    D. 16

    A day length of 16 hours maintains egg production.

25. Debeaking in poultry is done mainly to prevent:

    1. cannibalism
    2. feather moulting
    3. calcium loss
    4. egg eating by rats
    Answer

    A. cannibalism

    Beak trimming limits pecking injuries and feed wastage.

26. Which is the main energy ingredient in poultry feed?

    1. Maize
    2. Soybean meal
    3. Limestone
    4. Fish meal
    Answer

    A. Maize

    Maize is the main energy feed; soybean meal provides protein.

27. Extra calcium is given in layer mash mainly for:

    1. broiler growth
    2. yolk colour
    3. egg shell formation
    4. feather colour
    Answer

    C. egg shell formation

    The shell is mostly calcium carbonate.

28. In the deep litter system, the litter is:

    1. never disturbed
    2. stirred regularly to keep it dry
    3. kept very wet
    4. made of sand only
    Answer

    B. stirred regularly to keep it dry

    Dry, turned litter reduces ammonia and disease.

29. A low FCR in broilers indicates:

    1. poor efficiency
    2. low growth rate
    3. low egg production
    4. better feed efficiency
    Answer

    D. better feed efficiency

    Less feed is needed per kg of gain.

30. A buffalo gives 12 litres of milk with 7 % fat. Taking 1 litre as 1 kg, the fat yield is:

    1. 0.7 kg
    2. 0.84 kg
    3. 8.4 kg
    4. 0.084 kg
    Answer

    B. 0.84 kg

    12 x 0.07 = 0.84 kg.

31. A flock of 400 hens laid 300 eggs in one day. Hen-day egg production is:

    1. 75 %
    2. 30 %
    3. 60 %
    4. 133 %
    Answer

    A. 75 %

    300 / 400 x 100 = 75 %.

32. A broiler consumed 4.2 kg feed and weighed 2.1 kg. The FCR is:

    1. 8.8
    2. 0.5
    3. 2.0
    4. 1.0
    Answer

    C. 2.0

    4.2 / 2.1 = 2.0.

33. 1,000 eggs were set; 800 were fertile. Fertility percentage is:

    1. 8 %
    2. 100 %
    3. 20 %
    4. 80 %
    Answer

    D. 80 %

    800 / 1,000 x 100 = 80 %.

34. Of 800 fertile eggs, 640 chicks hatched. Hatchability of fertile eggs is:

    1. 80 %
    2. 64 %
    3. 90 %
    4. 160 %
    Answer

    A. 80 %

    640 / 800 x 100 = 80 %.

35. To prepare 100 litres of milk with 3 % fat from buffalo milk (6 % fat) and skim milk (0 % fat), the volume of skim milk needed is:

    1. 25 litres
    2. 50 litres
    3. 30 litres
    4. 75 litres
    Answer

    B. 50 litres

    Pearson square gives 3 parts : 3 parts; half is skim milk.

36. Chicken eggs set on 10 March will hatch on:

    1. 24 March
    2. 7 April
    3. 31 March
    4. 28 March
    Answer

    C. 31 March

    10 March + 21 days = 31 March.

37. A cow gives 15 litres of milk per day for a 305-day lactation. Her lactation yield is about:

    1. 3,050 litres
    2. 5,000 litres
    3. 4,500 litres
    4. 4,575 litres
    Answer

    D. 4,575 litres

    15 x 305 = 4,575 litres.

38. Total solids of milk with 4 % fat and 8.5 % SNF are:

    1. 12.5 %
    2. 8.5 %
    3. 32 %
    4. 4.5 %
    Answer

    A. 12.5 %

    Total solids = fat + SNF = 12.5 %.

39. From 200 kg of cow milk at 4 % fat, the fat present is:

    1. 0.8 kg
    2. 8 kg
    3. 4 kg
    4. 80 kg
    Answer

    B. 8 kg

    200 x 0.04 = 8 kg.

40. 100 kg of cream with 40 % fat is churned into butter containing 80 % fat. Ignoring losses, the butter obtained is about:

    1. 32 kg
    2. 80 kg
    3. 50 kg
    4. 40 kg
    Answer

    C. 50 kg

    Fat = 40 kg; butter = 40 / 0.80 = 50 kg.

41. Milk A has 6 % fat and milk B has 3 % fat. To obtain 4 % fat, A and B must be mixed in the ratio (A : B):

    1. 2 : 1
    2. 1 : 1
    3. 3 : 1
    4. 1 : 2
    Answer

    D. 1 : 2

    Parts of A = 4 - 3 = 1; parts of B = 6 - 4 = 2.

42. Consider the statements: 1. Casein is the main protein of milk. 2. Butter has a higher fat percentage than ghee. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Ghee has about 99.5 % fat, butter about 80 %.

43. Consider the statements: 1. UHT milk can be stored without refrigeration if aseptically packed. 2. Pasteurised milk can be stored at room temperature for months. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Pasteurised milk needs refrigeration.

44. Consider the statements: 1. Prolactin supports milk synthesis. 2. Oxytocin triggers milk let-down. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct.

45. Match: (a) Khaki Campbell, (b) White Leghorn, (c) Cornish with (i) meat fowl, (ii) laying duck, (iii) laying fowl. Which is correct?

    1. a-i, b-iii, c-ii
    2. a-iii, b-ii, c-i
    3. a-ii, b-i, c-iii
    4. a-ii, b-iii, c-i
    Answer

    D. a-ii, b-iii, c-i

    Khaki Campbell is a duck, White Leghorn a layer, Cornish a meat breed.