Thursday, July 7, 2011

Genetics and livestock improvement

Additive effect – the effect of each allele in the locus where no interaction exists.


Chromosome number – diploid (2n) complement.

- haploid (n) complement

- composed of autosomes and sex chromosomes

Cloning – process of replicating an individual out of its own body cells.

Charles Darwin – proposed the theory of evolution in his book “The Origin of Species” in 1859.

Evolution – the long process of change in the characteristics of organisms that result into new species.

Genetics – the study of the nature and function of genes.

Genetic parameters – heritability, repeatability, covariance, correlation

Gene frequency – the proportion of a particular gene at a given locus.

Generation interval – average age of parents when offspring are born.

Genotypic frequency – the proportion of a particular phenotype present in the population or a breeding group.

Gregor Mendel – an Austrian monk who founded genetics through his studies on crossbreeding of garden Peas in 1865.

Heritability – the degree by which a character is genetically transmitted from a parent to offspring.

Hugo de Vries, Carl Correns, and Erik von Tschermark (1901) – independently rediscovered the works of Mendel that the modern concept of inheritance started to be understood and accepted.

Jay Lush – American scientist who introduced the application of the various theories of the genetics of population to the practice of animal breeding.

Mendelian traits – governed by few pairs of genes.

1. qualitative

2. discreet classes

3. independent segregation

4. independent assortment

5. coat/plumage color

6. presence/absence of horns

Outbreeding – mating of individuals closely related than the average of the population. Other form includes crossbreeding, upgrading, topcrossing, interspecific (between species) and intraspecific (within species).

Recessive – the state where the expression of a gene is suppressed by it alternative allelic gene.

Response to selection - function of heritability and selection differential.

Ronald Fisher – British scientist responsible for the integration of the concept of Darwinian evolution and Mendelian inheritance into the discipline of population genetics.

Selection differential – is the difference between the mean of the selected parents and the mean of the base population.

Selection methods – based on records of individuals and/or relatives.

Selection procedures for simultaneous trait improvement

1. Tandem

2. Independent culling level

3. Index selection

Sewall Wright – American biologist who contributed significantly to the integration of evolutionary and genetic theories into the study of population genetics.

William Bateson – English biologist who found in 1906 that Mendelian inheritance applied to animals (chicken).

Wilhelm Johannsen (1909) – a Danish biologist who coined the term “gene” to refer to the particulate factor that Mendel hypothesized as the basic unit of inheritance.


Genes and their functions

Francis Crick proposed the biochemical nature of the genes together with James Watson in 1950.

Gene – carrier of hereditary characteristics.

 a segment of the DNA (abbreviation of deoxyribonucleic acid, a biochemical substance that bear the genes) that determines the base sequence of the nucleotide in the mRNA (acronym for messenger mRNA the biochemical substance that transcribes the genetic code in the process of protein synthesis) that makes up the code for a certain biological function

 occurs in pairs

 coined by Johannsen

 helical structure by Crick and Watson

 located in the chromosomes

 located in the sex chromosomes

The DNA is a biochemical compound consisting of a chain of nucleotides called polynucleotide. Each nucleotide consists of phosphate (P), a sugar (S), and a base (B). The coding system of the gene is based on the arrangement of the four bases, namely; guanine (G), adenine (A), thymine (T), and cytosine (C).

Functions of genes

1. copy and replicate itself

2. store and transmit genetic information

3. undergo mutation

The manner by which the genetic information is transmitted from cell to cell is made possible through somatic cell division (mitosis). The transmission of the genetic material from parent to offspring is made possible through the reduction division of the germinal cells (meiosis) and subsequent union of gametes (the collective term for the reproductive cells from either the male or female).

The DNA segment consists of two strands of the chain of bases. These two strands arte linked together at each of the base so that it forms a helical shape or a twisted ladder. The nature of the gene is such that each base in one strand can only pair with a specific base. Thus, adenine (A) could only pair with thymine (T) and guanine (G) could only pair with cytosine (C).

In spite of the consistency and the precision by which gene copies itself, mistakes, even if they are rare, occur. These mistakes are copied and become incorporated as part of the genetic information itself. Such mistakes are called mutations. If the mutation occurs in the somatic cell, then it is transmitted only from cell to cell in the same individual. But if it occurs in the germinal cell, then it may be transmitted to the next generation.

Genes provides the code for the synthesis of proteins through a process of transcription (process whereby the sequence of the bases in the DNA is transcribed by the mRNA in the nucleus for subsequent translation into the corresponding protein material) and translation (process of synthesis of the polypeptide chain based on the base sequence in the mRNA) involving the RNA and the ribosome in the cell.

The role of genotype and environment on the phenotypic

Genotype – the specific combination of genes in the diploid phase representing a phenotype. It is assemblage of gene in an individual.

- determined at the time of fertilization

- genetic make-up

- genetic constitution

Environment – the external factor, other than the genes that affects the character of an individual.

- non-genetic factor

- modifies phenotypic expression

- nutrition, climate, management, season, housing, etc.


Phenotype – the observable effect of a gene action. It is a function of gene and environment.

- outward manifestation of a genotype

- traits

- characteristics

- measurable

- expressed at different stages in life

- same as genotype if effect of environment is zero

- qualitative or quantitative

- production, reproduction and adaptation

- economically important or not

The G x E may be defined as the interaction between the genotype of the individual and the environment under which it is raised. The effect of Genotype x environment interaction when certain genotypes perform well under certain environments than other genotype, e.g. the Zebu (humped) cattle grow and reproduce better in arm tropical environment than the European (humpless) cattle.

Gene action

Genes may be active only when they occur in pairs of alleles during the diploid phase.

Allelic genes – genes that occupy the same locus (the specific location of a pair of genes in the chromosomes) in the chromosome (the colored bodies in the nucleus that contain the DNA).

Genes perform different roles. There are the structural genes which are directly responsible for the synthesis of certain biochemical products during cell metabolism and there are also the regulator genes which serve to control or regulate the function of other genes. Regulator genes may function in terms of quantity, quality or timing of the activity of certain structural genes.

Action of genes may be detected only from the phenotype. The action of genes as they influence genotypic values may be any or a combination of the following types:

a. Partial dominance or incomplete dominance – when a pair of allelic genes contribute independently to the genotypic value, the action of the gene is said to be additive. It is intra-allelic interactions.

- example:

 when a red (NN) cattle is mated to a white (nn) one the progeny is roan (Nn)

b. Complete dominance – when a gene suppresses the expression of its allele, the former is called the dominant gene while the later is referred to as the recessive gene. It is intra-allelic interactions.

- example:

 when homozygous pea comb (genotype PP) and a single comb (genotype pp) are crossed, the progeny will be heterozygous pea comb (genotype Pp)

c. Epistasis – from the Greek word which means “to stand upon”. It is a type of genetic interaction where a gene in one locus suppresses the action of a gene in another locus.

- example:

 in chickens, the presence of a dominant gene C at the C-c locus and the dominant gene O at the O-o locus enables the individual to synthesize the color pigment for its feathers. But in the presence of a dominant I gene at the I-i locus, the action of C and O genes in inhibited.

The mechanics of inheritance

1. Gametogenesis and fertilization

- gametogenesis, the process of production of gametes

a. spermatogenesis – process of producing sperm cells

b. oogenesis - process of production of female gametes

- fertilization, the process of introduction of the sperm cell into the egg to form a zygote

2. The Mendelian inheritance


- laws of inheritance:

a. Laws of segregation – characters are determined by particulate factors (later given the term genes) and that these factors occur in pairs. In the formation of gametes, these factors are segregated so that only one of the pair is transmitted by a particular gamete.

b. Laws of independence – in the formation of gametes, members of one pair of genes segregate independently of other pairs.


3. Non-mendelian inheritance

- governed by many pairs of genes interacting with one another:

a. Sex-linkage – the state where a gene is located in the sex chromosomes

- mammals: XY-male; XX-female

- birds: ZZ-male; ZW-female

- homogametic, the sex that carries identical sex chromosomes, e.g. X and X in mammals

- heterogametic, the sex that carries the different sex chromosomes, e.g. X and Y in mammals

- there are known to be sex-linked, these include hemophilia and color blindness, barring plumage pattern and dwarfism

b. Autosomal linkage – state when the genes are located in the same autosome (the type of chromosome other than the sex chromosome)

- parental type of gametes, those that were similar to what the offspring received from the parents

- recombinant type of gametes, those that are different from what was received from either of the parents but were produced as a result of crossing over of chromosomes during meiosis

- test-crossing, crossing of an individual of unknown genotype

c. Non-nuclear inheritance – in this case, the females would play a larger role than the male in influencing the characteristics of the progeny since the sperm cells have very little, if any, cytoplasmic material

d. Quantitative traits

e. Continuous distribution

f. Sex-influenced

Maternal influence – the mother could further influence the characteristics of her offspring because of the maternal care she provides to her young.

Genes in Populations

- populations, a group of individual sharing a common gene pool

- gene pool, is the totality of the genes that could potentially be transmitted by individuals in a populations to the next generation

1. Genetic composition of animal population

-populations are characterized by the frequencies in which the genes and genotypes occur in them

2. Equilibrium population – a population in which the genes and genotypic frequencies do not change generation after generation

- Hardy-Weinberg Law, gene and genotypic frequency remain constant from generation to generation if population is large, there is random mating and there is absence or if there is balance of selection, migration and mutation. Hardy (British mathematician) and Weinberg (German physician) independently formulated the principle in 1908

- violation in Hardy-Weinberg equilibrium:
a. small population leads to genetic drift

b. assortative or dissortative mating

c. natural or artificial selection

d. movement of animals through importation of live animals, semen or embryo

e. change in biochemical structure of genes

3. Factors affecting change in the genetic composition of populations

a. Selection – process where certain individuals are able to contribute more progeny in the next generation than other individuals

- natural selection, natural forces

- artificial selection, intervention of man

b. Migration – process of movement of individuals from one population to another population

c. Mutation – spontaneous change in the biochemical or structural characteristics in the genetic material that results in a different biological action

d. Small population size

e. Non-random mating – occurs when some individuals do not have the same chances of mating with individuals of the opposite sex


- forms of non-random mating:

 Assortative mating – individuals that are more phenotypically similar tend to mate more often

 Disassortative mating – individuals which are less phenotypically similar tend to mate more often together than would be expected by chance

 Inbreeding

Unit 7: Animal Breeding

- the art and science of genetic improvement of farm animals

1. Objectives of animal breeding

a. improve the quantity of production

b. improve the efficiency of production

c. improve the quality of farm animals

d. improve the aesthetic value of farm animals

2. Systems of animal breeding

a. Selection

b. Inbreeding – the process of mating animals that are closely related by descent

- increase genetic homozygosity

- inbreeding depression

- lowly heritable traits

- closest possible inbreeding animals is full-sib mating and parent-offspring mating

- inbreeding may be achieved by:

 irregular systems, the relationship between mates in the pedigree is vary

 regular systems, the relationship between mates is constant throughout the generations

c. Crossbreeding – the breeding of individuals from one population to individuals from another distinctly different population

- hybrid vigor or heterosis, a condition where the heterozygote is better than the average of the homozygote

 F1 progeny is better than the average of the parents

 Better than the average of the better parent

 Occurring on lowly heritable traits

 Caused by non-additive gene action (dominance, epistasis) higher than in the F1 than in the F2


Unit 8: Reproduction

- reproductive cycle and rate of genetic improvement

- frequency of ovulation and length of embryonic development:



Artificial insemination – techniques of introducing semen into the oviduct without the benefit of the male

- effective if the superior animal is the male

- benefit derived from artificial insemination:

a. the number of female that could be mated by a single male is increased dramatically

b. STD are minimized

c. male that are physically unable to mate naturally may still be used fro breeding

d. semen of bulls that have been long dead may still be used for inseminating cows

e. because the number of progeny that could be produced by a single male is increased the accuracy of evaluating the breeding value of a male is increased proportionately


Multiple ovulation and embryo transfer (MOET) – a process of hastening the reproductive rate of female animals

- effective if the superior animal is the female

- multiple ovulation, process by which the female animal is induced to simultaneously ovulate more eggs than what is normally shed

- embryo transfer, technique wherein a young embryo is collected from a donor female parent and then implanted into the uterus of a recipient female parent

Sexing semen – separating the fraction of the semen that would carry a much larger proportion of sperm cells carrying the Y-chromosomes than those that carry the X-chromosomes.

In vitro fertilization – experimentally induced biological processes outside the organisms.

Nuclear cloning – continued splitting of embryos that would lead to an indefinite duplication of an individual





Chapter 4: Slaughter, Processing and Marketing of Farm Animals

Unit 9: Slaughtering and fabrication

Unit 10: Composition of meat, milk and eggs

Unit 11: Basic principles of proper handling and processing of meat, milk and egg

Unit 12: Marketing of livestock and livestock products

Unit 9: Slaughtering and Fabrication

Definition of terms

Meat terms:

Meat – the carcass or carcass parts coming from animals sufficiently mature and healthy

Beef – meat from cattle more than one year old

Veal – meat from cattle less than one year old

Carabeef – meat from carabao more than one year old

Chevon – meat from goats

Pork – meat from swine

Mutton – meat from sheep

Lamb – meat from lambs

Venison – meat from deers

Hot meat – meat coming from an illegal source

Fresh meat – meat that has not undergone any substantial physical, chemical and microbiological changes from the time of slaughter

Meat by-products – the edible by-products from the slaughterhouse

Abattoir – the premises approved and registered as premises for slaughtering animals for human food

Cold slaughter – slaughtering an animal dead of some causes prior to slaughter

Fabrication – process of cutting carcasses into standard wholesale and retail cuts

Flaying – a ct of removing hide from animals

Corned meat – prepared meat cured by soaking with or without one or more of nitrate, nitrite, sugar dextrose, syrup, honey and with or without the use of spices

Curing – the addition of salt with or without nitrite, nitrate and sugar for the purpose of lengthening shelf life and/or enhancing the development of odor, color, and flavor

Quick freezing – freezing products at a temperature of -20 °F or lower

Green hams – unsmoked cured hams

Hot boned meat – meat deboned before the development of rigor mortis

Milk terms:

Pasteurization – it is a process of heating a foodstuff, usually liquid, for a definite time at a definite temperature and thereafter cooling it immediately. US public health service recommends heating milk to at least 145 °F for at least 15 seconds

Homogenization – fat globules are subjected to mechanical treatment, which breaks them down into smaller globules, uniformly dispersed in the milk

Certified milk – fresh milk of higher purity to be delivered to the customer within 36 hours. The number of bacteria is 10,000 or less per ml

Pasteurized milk – milk heated to a temperature of not lower than 145 °F for a period of not less than 30 minutes

Homogenized milk – milk than contains finer globules of butterfat than those present in fresh milk. It is prepared by passing fresh milk through small openings by pressure.

Evaporated milk – fresh milk which has been evaporated to a concentration of 73.7 % water. It contains 7 % protein, 7.9 % fat, 9.9 % lactose and 1 % minerals

Condensed milk – concentrated milk to which sugar has been added. It has 27 % water, 8.1 % protein, 54.8 % lactose and 1.7 % minerals

Filled milk – milk where the butterfat is replaced with vegetable fat such as coconut fat

Dried or powdered milk – dried milk obtained by evaporating the moisture from the milk solids

Recombined milk – dry skim milk, dry buttermilk plus butter oil

Reconstituted milk – milk powder plus water

Basic principles of selecting animals prior for slaughter

- the basic considerations in selecting animals are as follows:

a. sex consideration

b. age consideration

c. size consideration

d. class considerations

e. health consideration

f. finish considerations

Management of Animals Prior to Slaughter

There are four management practices given to animals prior to slaughter. These are fasting, allowing animals to relax, handling them gently and keeping them as clean as possible.

Fasting

 Feed is not given to the animal, however, sufficient amount of water is provided. Simple stomach animals are fasted for 12 to 24 hours whereas the ruminants are fasted for 24 to 48 hours. Advantages of fasting include savings of feeds, ease of cleaning entrails and eviscerating carcasses, thoroughly bled and brightly colored carcass, long shelf life and low shrinkage of resulting meat.

Relaxed animal

 No form of stress should be given to animal prior to slaughter. If stress cannot be avoided, animals must be given enough time to rest and gain their composure before they are slaughtered. One to three-day relaxation in the holding pen is enough to remove the effects of stress on the animal depending on the degree of stress.

 The disadvantages of stress include loss of muscle glycogen, high temperature of carcass, low water holding/binding capacity of resulting meat, low aroma, flavor, texture and juiciness scores.

Handling animal gently

 The part of an animal whipped, kicked or boxed prior to slaughter develops blood clots and red spots in the meat. Blood clots in meat are support for luxuriant growth of microorganisms and cause accelerated meat spoilage.

Clean animal

 Good sanitation practice is best started by keeping the animal clean. One of the worst contaminants of meat is the micro flora abundant in feces.

Basic requirements in slaughtering animals

 Basic factors to consider in slaughtering:

1. cleanliness of meat produced

2. hygiene or production

3. efficiency of meat inspection

4. adequacy of meat preservation

 The slaughterhouse:

1. There must be complete facilities for the proper care of animals prior to slaughter.

2. The slaughterhouse should have separate rooms for the slaughter of swine and ruminants.

3. The slaughterhouse must have good drainage and ventilation, must be at least 100 meters away from residential houses and must have adequate pollution control device.

 Classification of slaughterhouse in the Philippines:

1. AAA – those with facilities and operational procedures so adequate that the meat processed herein is eligible for sale in any market in and out of the country.

2. AA – those with facilities and operational procedures sufficiently adequate that the meat processed herein is eligible for sale in any market in the Philippines.

3. A – those with facilities and operational procedures of minimum adequacy as defined by the National Meat Inspection Commission (NMIC), the meat processes herein is eligible for sale only in the city or municipality in which the plant is located.

4. Non-accredited – those with facilities and operational procedures of less than minimum standards that must be closed until minimum standards are provided or achieved.

Slaughtering animals

1. Ante-mortem inspection – is determining whether an animal is fit for slaughter or not.

2. Stunning – is making animals unconscious but not killing them.

3. Sticking – animals must be stuck within 3 minutes after stunning.

4. Cleaning of the carcass – vary within species. There are three distinct methods of cleaning carcasses:

a. Flaying – is removing the hide. This is commonly done in carabaos, cattle, horses and goats.

b. Scalding – is submerging the carcass in hot water to loosen the hairs and scurf. Scalding is necessarily followed by scraping. The temperature of scalding water must be controlled at 130-180 °F.

c. Singering - is burning the hairs and scraping the hairs as soon as these are burned. This is commonly done in goats.

5. Evisceration – starts from the time cuts to open the carcasses are made and end when the slaughter by-products are removed from the body cavity.

6. Splitting/washing – splitting is cutting the carcass into two equal parts. The carcass must be splitted at the backbone, but the tail normally goes with the left side if it is not removed before cutting. Right after splitting the carcass is washed very thoroughly and the parts with blood clots are trimmed.

7. Post-mortem inspection – this is inspecting the carcass for final determination whether it is fit for human consumption or not.

8. Shrouding – is wrapping the carcass with cheesecloth.

9. Chilling – the chilling room where carcasses are laced after slaughter should have a temperature of 0-4 °C (32-40 °F).

10. Aging – is holding the meat for 7-14 days at 36 °F to improve tenderness and flavor of meat.

Meat fabrication

Fabrication is cutting carcasses into standard wholesale and retail cuts.

 Four principles to follow in cutting carcasses:

1. thick portions must be separated from the thin ones

2. the tender parts must be separated from the less tender portions

3. the high priced cuts are separated from the less expensive parts

4. cuts must be made across the muscle fibers

 Dressing yield of common livestock and poultry:

Dressing % = carcass weight / slaughter x 100

- obtained after 24-48 hours chilling without the head and internal organs

Lean-fat-bone yield = component / live weight x 100

Boneless recovery = boneless carcass / live weight x 100

Unit 10: Composition of Meat, Milk and Eggs

The meat

 General characteristics

1. Meat is a high quality, concentrated and easily digested source of nutrients and is well balanced with regard to the relative amounts of specific nutrients which it contains. It is an excellent source of high quality protein, B-complex vitamins and of certain minerals.

2. Meat provides satiety unequaled by other food items, it can be prepared in several ways and it provides nutrients almost in the proportion and amount needed by the human body. Because of its high nutritive content, microorganisms also love to attack it, hence spoils fast at ordinary room temperature.

 Physical component of meat

a. The basic structures that can be seen in meat are lean, fat, bone, skin, connective tissues, and blood vessels. Some meat cuts have also noticeable bone marrow inside the bones.

b. The lean or muscle is considered the most important among the components because of its palatability and nutritive value. Muscle also comprises the bulk of the carcass (about 50-65 %).

c. The fat tissues are the most variable constituents of meat. The amount of fat in the body is markedly influenced by the diet, age, exercise and other physiological factors.

d. The amount of connective tissues is also important in meat because it determines the tenderness or toughness of the meat. The higher the amount of connective tissues, the tougher the meat is.

 Chemical composition of meat

- The chemical composition of meat is usually presented by its proximate composition. The proximate composition of meat varies depending on:

1. species from which the meat was obtained

2. degree of fatness to which the animal has been fed

3. specific cut used

4. extend of cutting and trimming

5. curing and processing treatment

Relationship of physical structure and chemical composition to the eating qualities of meat

1. kind of protein

2. amount of fat specifically marbling

3. carbohydrates

4. moisture content

5. nitrogenous extractives

6. connective tissues

7. muscle fibers bundle

 Nutritional value of meat

1. connective tissues proteins have high amount of proline, hydroxyproline, and glycine and has low tryptophan and tyrosine

2. meat is an excellent source of the B vitamins, phosphorus and iron but relatively low in calcium. The cooking and processing of meats do not appreciably affect the quantity or availability of the mineral elements present as long when mineral salts are added.

The milk

 General characteristics of milk

1. Milk ranges from a bluish white to almost golden yellow color. In large quantities, milk appears entirely opaque.

2. Milk has no pronounced taste but slightly sweet to most persons. Freshly drawn milk has low characteristics odor but gets lost upon exposure to air.

3. The pH of fresh milk is about 6.5. When milk is allowed to stand undisturbed for a few hours, a layer forms on the surface. This layer is the cream which is composed of fat globules.

4. Since milk is very nutritious, microorganisms grow in it very fast and spoil it. The normal freezing point is -0.545 °C.

 Chemical composition of milk

1. Water is the principal constituents of milk. It is about 78-88 % (average of 87 %) of the fresh whole milk.

2. Fats are also present in the form of fat globules which amount to 3-10 % of milk. Fats are very good absorber of flavor and odor and usually come into two forms:

a. true fat (glycerides)

b. associated substances (lecithin, cholesterol, carotene, vit. A, D and E)

3. Carbohydrates in milk are in the form of lactose, which is about 4-5 % (average of 4.9 %) of the milk. Lactose is complex disaccharide made up of glucose and galactose. This is easily fermented by microorganisms to lactic acid.

4. Nitrogenous component of milk is made up of 95 % protein and 5 % non-protein. The milk has around 3-6 % protein. The 78.5 % of protein in milk is casein while 16.5 % rest is milk serum protein. The protein milk is considered as of high quality; almost the same as in meat, but a little bit lower than that of egg. Milk protein is slightly deficient is sulfur containing amino acid.

5. Milk has 0.7-1.0 % ash or inorganic minerals. Milk is a rich source of calcium, magnesium, phosphate and citrate.

The colostrums has 73.79 % water, 1.17 % protein, 6.74 % fat, 2.30 % lactose and 1.0 % ash while human has 87.6 % water, 1.2 % protein, 3.8 % fat, 7.0 % lactose and 0.4 % ash.

 Nutritional value of milk

1. Milk contains broad distribution of nutrients. Milk is especially rich in high-quality protein, calcium, phosphorus, riboflavin, ands other B vitamins. It is poorer source of vitamin D, C, and iron.

2. Milk protein is one of the highest quality proteins. The only principal deficiency of milk protein is the sulfur containing amino acids: cystine and methionine. It is very rich in lysine. Milk lipids, however, contain high saturated fatty acids and low linoleic acid and linolenic fatty acid.

3. The fat-soluble vitamins of milk exist partially in a free state and partially bound to proteins. There, the biological activity of the bound forms may-depend on their release upon ingestion.

The egg

 General characteristics

The egg is compact package of well-balanced food nutrients. Eggs have high protein, very low in carbohydrate, have high vitamin A, riboflavin and vitamin D. it is richest source of iron in animal foods. One chicken egg weighs on the average about 50-60 grams. Calcium is in the form of CaCO3.





 Constituent of egg

The egg is basically composed of around 31 % yolk, 59 % albumen or white and 10 % shell. The yolk is made up of 47-48 % moisture, 16 % protein, 32-35 % ether extract or fat and around 1 % carbohydrate. The ether extract component of yolk contains phospholipids, triglycerides and cholesterol. On the other hand, the albumen is made up of 87-89 % moisture, 9.7-10.6 % protein, 0.5-0.6 % ash, 0.03 % fat and 0.5-0.9 % carbohydrates.

Common tests to determine composition of meat, milk and egg:

Composition Laboratory Analyses

Meat Milk Egg

Moisture Oven drying Oven drying /use of lactometer Oven drying

Total solids Oven drying Use of lactometer Oven drying

Ash Ignition Ignition Ignition

Crude fat Ether extraction /Babcock test Ether extraction Babcock test

CP Kjeldahl analysis Kjeldahl analysis Kjeldahl analysis

Casein N/A Walker method N/A



Measures of egg quality:

1. Whole egg characteristics

• Size, shape, color, texture, cleanliness, uniformity of eggs

• Floatation test

2. Candling characteristics

• shell, air cell, yolk, white and germ

• bubbly air cell – state, weak shell membrane, rough handling

• air cell moves – broken inner membrane

• normal yolk – faint shadow at the center of egg

• abnormal yolk – moves freely and casts darker shadow

• old egg – floats

• high quality egg has no germ development (blood begins to show after 48 hours at 100-103 °F)

3. Broken out odor, flavor, physical characteristics

• normal – yolk is well rounded

• old – flattered and spread out

• haugh unit – height of yolk – log of albumen

- height corrected to standard egg weight of 2.03

HU = 100 log {H – [G (30 W – 37 – 100) + /g] / 100}

HU – Haugh units

H – Albumen height

G – Gravitational constant

W – Weight of eggs

- simplified formula:

HU = 100 log (H + 7.57 – 1.7 W – 37)

4. Other measures of quality

• yolk index = measures of the standing up quality of yolk

= height of yolk / diameter

0.42 – 0.4 = normal

0.25 = low

Unit 11: Basic Principles of Proper Handling and Processing of Meat, Milk and Egg

Causes of deterioration

 Categories:

1. Biological forces. Biological spoilages may also be brought about by flies, rodents and cockroaches. Spoilages of these kinds are however easy to control. Working in ideal rooms may entirely eliminate insect spoilage problems.

2. Chemical forces. Oxidation is a common chemical cause of meat, milk and egg deterioration. Oxidation of the fats causes rancidity while oxidation of the color pigment in meat causes darkening.

3. Physical forces. Dehydration and enzymatic action are two of the physical processes causing food deterioration. These two are expensive to minimize and very impractical to completely stop or control.

Processing of meat

 Meat processing refers to any or combination of process utilized in altering fresh meat.

1. Cold storage may be divided into chilling and freezing.

a. Chilling is subjecting meat to a temperature of 32-40 0F (0-4 0C). There is rapid cooling but there is no hardening and freezing of meat juices.

b. Freezing of meat is either slow or quick freezing. The meat hardens in 30 minutes in quick freezing. Longer time is required in slow freezing. Quick freezing on the other hand can be accomplished by blast, deep, cryogenic, direct immersion, indirect immersion, indirect contact and spray freezing. Quick freezing is more advantageous than slow freezing because there is less destruction of the muscle fibers, less drip, minimal loss of water holding capacity and flavor of product.

2. Drying meat is lowering the available water in meat. This can be done by withdrawing the water by binding the water and renders it unavailable for microbial growth.

3. Salting is accomplished by the addition of salt, hypochlorite of calcium and/or other salts. Through osmosis, salts withdraw water from meat and causes plasmolysis of bacterial cells. Salts also ionize to yield chlorine ion, which is harmful to organisms. Other action of salts include reducing the availability of oxygen in the moisture, sensitizing bacterial cells to carbon dioxide, reducing the action of proteolytic enzymes and accelerating development of rancidity.

4. Canning is hermetically sealing of meat in a container and then subjecting it to thermal process. All the organisms present are killed in this process and the product is considered commercially sterile.

5. Curing started as a method of meat preservation; however, as time went by, people developed the liking for cured flavor. There are basic ingredients required in meat curing. These are salt, sugar, and nitrate/nitrite.

Ordinary table salt is the major portion of the curing ingredients. It inhibits the growth of putrefying bacteria, hardens muscle fibers and draws out moisture from the meat. Together with other ingredients, it adds desirable flavor and texture to the meat.

Sugar adds flavor, helps overcome saltiness and counteracts the toughening effect of salt. It is also utilized as media by some beneficial organisms.

Nitrate/nitrite helps develop cured color and flavor and inhibit microbial growth.

Quality in meat

 The word quality infers superiority and degree of excellence

 Measures used to evaluate quality in meat:

1. Lean color

- Bright colored meat gives so much appeal to the consumer

- Indicates how long a cut of meat has been held on meat stall

- Improves selling or marketability of meat

- Helps identify species of animals from which the meat is taken

2. Lean firmness

3. Lean texture

4. Marbling

5. Age or maturity of the carcasses

Milk processing

1. Straining – right after milking, the milk is strained using sterilized cheesecloth.

2. Cooling milk – the milk should be cooled to 50 0F of lower as soon as it is milked out to minimize microbial growth.

3. Clarification and filtration – this process is done to further remove dirt, which were not removed during straining. Clarification is the by the use of the principle of centrifugation, while filtration is using the principle of filter paper.

4. Separation – this is separating the cream and the skim milk. This can be accomplished by either gravity method or using a mechanical cream separator.

5. Pasteurization – treating milk with heat thereafter followed by rapid cooling to destroy bacteria. About 98.99 % of bacterial cells die. Pasteurization can be done by either:

a. Holding process – milk is heated to 145 0F (62. 8 0C) for 30 minutes, then cooled rapidly/.

b. Flash process:

- HTST (High temperature short time) – milk is heated at 165-185 0F (73.9-82.2 0C) for 15 seconds.

- UHT (Ultra high temperature) – milk is heated at 192-194 0F (80-90 0C) for 1 to 4 seconds.

6. Homogenization – forcing milk through small opening under high pressure. Normal pressure is from 2,500 – 5,000 psi. Fat particles are reduced to less than 2 microns in diameter.

Forms of milk in the market

1. Fresh whole milk

2. Whole milk powder – water is removed

3. Skim milk – fat or cream is removed

4. Skim milk powder (SKMP) – water is removed from the skim milk, also known as non-fat dry milk

5. Evaporated milk – some water removed

6. Condensed milk – more water removed plus water

7. Filled milk – SKMP = vegetable oil + Vitamin A and D

8. Homogenized – small fat globules (2,500-5,000 psi)

9. Flavored milk – SKMP + water + flavor

10. Whey powder

Unit 12: Marketing of Livestock and Livestock Products

Methods of marketing livestock in the Philippines

1. Livestock market/concentration yards - farmers or traders bring their animals to the concentration yards to sale. Markets usually have facilities for the care of animals. The transactions could be:

 trader to trader;

 farmer to trader; and

 trader to farmer.

2. Barrio agents – perform one or both of the following:

 buy livestock from scattered backyard farms and sell these to viajeros; and

 act as a viajero or wholesaler and sell livestock, directly to retailers. These agents are highly skilled especially in live weight estimation.

3. Wholesalers or viajeros – buys livestock in wholesale quantity, transport the livestock and resell them to wholesalers, retailers and/or processors.

4. City dealers – are the intermediaries between the provincial viajeros and the wholesalers in the cities.

5. Retailers – are those who buy animals and sell them to consumers. These are very common in goat marketing.

6. Contract growing schemes – there are several approaches used in contact scheme. In all of the schemes, a mother company takes the animals produced and takes care of the processing before final sale to consumers.

Problems commonly encountered in the marketing of livestock

1. No grade standards

2. Lack of integrated information

3. Difficulty of transporting animals

4. Cost of transportation is very high

5. Lack of suitable public transport system

Meat and Meat Products Marketing

Traditionally, the meat distribution system is multi-layered with many middlemen involved in the whole process. The most common is the five (5) level distribution system.

Producer ------- Barrio agent ------- Wholesaler ------- Retailer -------- End consumer

However, recent trends indicate that more producers have resorted to direct marketing system in an effort to reduce or totally eliminate the middlemen involved and maximize profits.

Producers ----- retailers

• wet market

• institutional markets

- supermarkets

- groceries

- hotels

- restaurants

Types of meat markets

1. Retailers

a. Wet markets – are those meat stalls in public markets where meat are usually hung in bulk and sliced only when a customer comes. Wholesalers usually supply meats for these markets.

b. Supermarket style/meat shops – are components or grocery stores, supermarket or individual meat shops. Meats are properly fabricated and handled.

2. Wholesalers

a. pack trading

b. packers to retailers

c. retail outlets

d. institutional outlets

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