Quick Review on Animal Breeding
- Animal breeding: Branch of animal science that addresses the evaluation (using best linear unbiased prediction and other methods) of the genetic value (estimated breeding value, EBV) of domestic livestock.
- Backcross: Backcross is the mating of a two–breed animal back to one of the two parental breeds
- Crossbreeding: Mating of different breeds to produce multi-breed offspring.
- Dominance: A dominant gene affects the appearance of the phenotype.
- Estimated Breeding Value (EBV): An estimate of an animal’s genetic merit for a particular trait based on the individual’s performance and the performance of relatives.
- Expected Progeny Difference (EPD): The expected difference between the progeny performance of a breed average animal and the performance of an individual’s progeny for any given trait(s). An animal’s EPD is ½ of its EBV and is equal to ½ (Sire EPD + Dam EPD).
- F1: Progeny resulting from the mating of a purebred ram and a purebred ewe of different breeds.
- Gnotype: The actual genetic make-up of an individual as determined by its genes.
- Half-sibs: Individuals who have the same sire or dam (i.e. half brothers and half sisters).
- Heredity: The transmission of characteristics from parents to their offspring through genes.
- Heritability: Is the proportion of a measured or observed trait that is transmitted to the offspring by genes.
- Heterosis (Hybrid Vigour): The increase in performance observed for a specific crossbred above the average performance of the parental lines.
- Heterozygous: Each gene of a specific gene pair is different in an individual (i.e. Aa).
- Homozygous: Each gene of a specific gene pair is the same in an individual (i.e. AA).
- Inbreeding: Production of progeny from closely related parents.
- Linebreeding: A form of inbreeding which increases the average relationship of the individuals in a flock to an outstanding ancestor or line of ancestors.
- Linecross: Progeny produced by crossing two or more inbred lines.
- Multiple Trait Selection: Selection for more than one trait at the same time.
- Mutation: A rare change in the DNA. Extent to which mutations influence the inheritance of farm livestock is not known precisely.
- Outcrossing: Mating of individuals within a breed that are not closely related.
- Persistency: The degree to which milk yield is maintained from month to month by the cow during her lactation.
- Pnetrance: The ability of a gene or group of genes to cause their characteristic to develop under the conditions of a particular environment.
- Pure breeding: Also straight breeding. The mating of purebreds of the same breed
- Random Mating: A mating system where all ewes have the same chance of being mated to any ram used.
- Rotational Crossbreeding: Systematic crossing of two or more breeds in which the crossbred ewes are mated to rams of the breed contributing the least genes to that ewe’s phenotype.
- Sibs (Full Sibs): Brothers and sisters from the same sire and dam.
- Super-ovulation: The administration of a hormone causing a female to develop and release more eggs than normal
THE CELL AND CELL DIVISION
- DNA molecule: 4 bases + a peptone sugar + A phosphate group
- Lysosomes (animal only) - production of intracellular digestive enzyme
- Mitochondria (rice shape)- Energy production (Kreb’s cycle), also called power house of cell which provide the 90% of the energy requirements
- Ribosome-Site of protein synthesis
- Plasma membrane- permeable membrane
- The smallest body cells are found in blood stream, while, and largest are nerve cells.
- Cell is the individual unit of living structure
- Robert Hooke of England applied the term “cell”
- Bases: Purines
@ In RNA Uracil is replaced by Thymine of DNA and pentose ribose is replaced by deoxyribose
- m-RNA: Carry coded information from DNA to ribosomes
- r-RNA: Part of ribosome
- t-RNA: or soluble RNA (s-RNA) recognize specific amino acids in the cytoplasm
@ There is at least one specific S-RNA for each amino acid.
1. Mitosis: Division of somatic cells when 2 daughter nuclei are formed with same chromosome as parent cell
- Interphase: Chromosomes are visible, centrosome divides into 2 parts of centrioles
- Prometaphase: Spidle mechanisms are formed
- Metaphase: Each chromosome 2 chromatids with single centromere
- Anaphase: 2 sister chromatids are converted to independent chrosomomes
- Telophase: Spindle disappear
Karyokinesis: Nuclear division
Cytokinesis: Cytoplasmic division
2. Meiosis: Division I: Prophase I:
- Leptonema: Bead like structure
- Zygonema: Synapsis, Zipper like
- Pachynema: Crossing over
- Diplonema: Chiasmata
- Diakinesis: Termination completed
Metaphase I, Anaphase I, Telophase I
Division II: Equational like mitosis cell division
SEGREGATION AND RECOMBINATION OF GENE
- Zygote: Fertilized egg before first cleavage
- Synapsis: Pairing of homologous chromosomes during prophase of meiosis I
- Sex limited traits: Traits controlled by gene located on the X-chromosome
- Sex limited gene expression: Heritable traits determined by only one sex (Beard in man)
- Sex influenced dominance: Dominance in one sex and recessive to other (Baldness in man)
- Pleiotropy: Where a single gene produced 2 or more phenotypic effects
- Multiple allele: 3 or more possible alleles (ABO blood group in humans)
- Autosomes: The chromosomes present in the same number in both sexes of any species
- Gregor Johann Mendel is called “father of Genetics”
- Law of segregation: Tall × Dwarf In mono hybrid cross: 3:1 (F1) and 1:2:1 (F2) ratio
CHROMOSOME NUMBER (2N)
- Cattle: 60, Horse: 64, Waterbuffalo: 50, Donkey(Ass): 62,
- Swamp buffalo: 48, Mule: 63, Goat: 60, Dog: 78, Sheep: 54,
- Cat: 38, Pig: 38, Foul: 78, Yak: 60, Elephant: 56 .
INDIGENEOUS BREEDS OF LIVESTOCK & POULTRY
- Siri (Local hilly cow):
- Black and white in colour
- Famous draft breed of esteem hills of Nepal (Ilam District)
- Fairly good milkers (360kg/lactation @1.5kg milk/day)
- Av. Body wt. 315kg, age of 1st calving 63 months, C.I-12-20 months
- World smallest breed of cow found in Nepal only
- They are less than 1 meter in height at withers
- Suitable in hill condition and low input system (Achham, Doti, Bajura)
- Body colour is varies from black and white.
- Maximum body wt. is 150 kg
- Av. Milk yield is 1.5 kg/day
- Found in Himalayn region of Nepal particularly in Mustang, Humla & Mugu districts (suitable for mid-hills)
- Good draught type animal located in far-western region of Nepal
- Larger indigenous breed in the country and difficult to handle
- Bulls and cows are breed with Naks and Yaks
- Av. Milk yield is 2.5 kg/day
- They are light coloured animal mostly white and suitable for terai region (hot climate)
- They are low milk yielder (2.1 kg/day) and good draught breed
- Use terai cattle for genetic improvement to the 62.5% of exotic breed & 37.5% to 50% terai cattle
- Small size Bos taurus cattle found in high mountains of Nepal (suitable for cool & dry place and good for low input system)
- This is the only breed of cattle in the country that is humpless.
- They are located in the Mustang and some parts of Manang & Dolpa
- Av. Milk yield is 1.6 kg/day
- They are mostly black in colour
- Located across the hills conditions and good draught breed
- Av. Milk yield is 1.1 kg/day
- Yak and Nak:
- They are the mountains (14,000-20,000 ft) cattle and localized in the northern belt of the country
- Body colour is varies from black and white.
- Chauries are good milk yielders and Jhopkyos are sterile & good for transportation as pack animals
- Wool production of Yak and Nak is 1.2 & 0.7 kg respectively
- Maximum body wt. is 355 (Yak) and 325 (Nak) kg
- Av. Milk yield is 0.6 kg/day with fat 6.6%
Mating of Yak (male) × hill cattle (female)
- Urang Chauri (female, fertile)
- Urang Jhopkyos (male, sterile)
Mating of Nak (female) × hill cattle (male)
- Dimgo Chauri (female, fertile)
- Dimgo Jhopkyos (male, sterile)
Mating of Yak (male) × Dimgo Chauri (female)
- Tolmu Chauri (female, fertile)
- Tolmu Jhopkyos (male, sterile)
- This buffalo is grey in colour with white hair colour around the jaw and brisket region
- Body medium sized with sickle shaped horns cuverd toward the back
- Can withstand under low pasture condition and resistant to disease
- Live wt. 250-400 kg, MY-255ltr/lactation, @2.1 ltr/Day, Fat 7.5%, CI-80wks, Calving period- Swrawa- Aswin, age of 1st calving- 4 years
- This buffalo is mainly black in colour with long face, black muzzle and flat head white hair colour around the jaw and brisket region
- Body medium sized with sword shaped horns directed toward the back
- Suitable for hills, high milk yielders, adaptable to brash environment
- MY-2.0-2.5 kg/day
- They are located in the far western region in Nepal
- This buffalo is mainly black in colour with white round patches on the forehead.
- Long face, flat face and horns are long half curved
- Suitable for hills, high milk yielders, adaptable to brash environment
- MY-4.6 kg/day
- They are located in the Mahabharata, mid hills region of Nepal & represent 56% of the total goat population of the country
- They are prolific and good for meat purpose of 30 kg body wt and 3.5% fat in milk
- They are hardy and well adopted in local environment
- Body color varied from white (Seti) to black (Kali)
- They are light coloured (mostly white) breed located in the Terai region
- Good meat types of breeds of 30 kg body wt.
- From conservation point of view they are at risk as it is difficult to find as a pure form
- Found in south hill mountains (1500-3000 m) of Nepal as pack animals
- They are heaviest native breed of goat and represent 16% of the total goat population of the country
- They are good meat and draught types of breeds of 35 kg body wt.
- Found in hill hills of Nepal as pack animals along with Bhyanglung type of sheep
- They represent 1% of the total goat population of the country
- They are used for meat and Mohair or Pashmina (cashmere=500-740gm) production
- Body color varied from pure white to pure black of 25-40 kg body wt.
- Suitable for lower hills, hardy, short tailed breed, course wool type & suitable for making radi/pakhi (Blankets)
- They represent 21% of the total sheep population of the country
- They are mainly used for wool and smallest among the indigenous breed with better prolificacy (18% twining)
- It is the purest Neplease breed of sheep
- Male are sickle shaped horns and female are polled.
- The coat colour is white except in the head region (brown)
- Av. Wt. is 16-24 kg, 3 lambing/2years, 700gm.year
- They extremely heat tolerance and suitable for terai region, hardy, long tailed (0.5-0.6m) breed, good fighting quality, meat type
- They represent 12% of the total sheep population of the country
- The body colour is mostly white
- Av. Wt. is 25-30 kg
- Suitable for hills, hardy, good grazing instinct, wool suitable for making radi/pakhi
- They represent 63% of the total sheep population of the country and concentrate in mountains (41%) & hills (22%)
- They are also used as pack animals
- Av. Wt. is 40kg (male) & 30kg (female) kg, Wool production 1.65kg (male) & 1.2kg (female)
- Bhyanglung: (Tibetan Sheep)
- Suitable for high hills (2500 -4000 m), hardy, carpet wool type
- They represent 4% of the total sheep population of the country
- Av. Wt. is 60-90 kg, Wool production 1.0kg/2shearing
- Found in the Northern part of Nepal
- They are the largest sized pig amongst indigenous breeds
- Suitable for terai, hardy, suitable for backyard rearing
- They are mainly used for meat
- They represent 23% of the total pig population of terai
- They are rust brown in colour, well suited for scavenging conditions
- Body wt. is 40-55 kg, produce 7 piglets in a litter with Av. Wt. of 0.8 kg
- Suitable for hills, hardy, suitable for backyard rearing
- They represent 58% of the total pig population of the country
- They are black in colour, hardy and well suited for local environment
- Body wt. is 25-40 kg, produce 5 piglets in a litter with Av. Wt. of 0.6 kg
- Bampudke (Sano bandel):
- They are the smallest hog breed in the world
- They are found in both wild and domestic form and are very hard animal, meat quality
- Found in Chitwan, Nawalparasi
- Body wt. is 18-25 kg
Poultry: Sakini, Pwankhulte, Ghantikhuile