Pig breeding system
The function of the breeding farm
Purebred breeding improves and breeds new strains; provides excellent purebred male and female sows for breeding grounds; provides excellent terminal boars for commodity farms; and provides excellent boars for artificial insemination stations. Summarized into one sentence: make it "more born, less dead, grow faster, breed well."
The main hybridization method
At present, the main hybridization methods include: binary hybridization, three-way hybridization, four-way hybridization, terminal hybridization, and terminal round hybridization. The advantages and disadvantages of different hybridization methods are different:
Advantages of binary crossbreeding: The highest offspring heterosis can be obtained and the method is simple. Disadvantages: No male or female heterosis can be obtained.
Advantages of three-way hybrids: The ability to obtain maximum maternal and offspring heterosis; Disadvantages: Must ensure that the purebred pigs used to produce the hybrid female parent, can not get the father advantage.
The advantages of four-way hybrids: Obtaining the highest male parent, female parent, and offspring heterosis; Disadvantages: Must maintain purebred pigs used to produce hybrid boars and sows.
Hybridization methods and disease control
Current Hybridization Methods: End-to-End Hybridization
Change the existing terminal hybridization mode to hybrid production for growth cycle mode or terminal cycle mode. If the market places a particular emphasis on lean meat, terminal round hybridization can be used.
reason:
1, to avoid the continued introduction of gilts, reduce the risk of disease.
2. Introduce the best boar semen from each generation to increase the genetic potential steadily
3. Reduce the number of original breeding farms
4. Reduce the level of breeding system and increase the speed of genetic diffusion
Selection of reserve pigs
Paternal and maternal pigs
Paternal pigs: breeds or strains involved in the production of parental boars, such as Duroc and Pietrain.
Maternal pigs: breeds or strains involved in the production of parental sows, such as Landrace and Great White.
The breeding objectives of paternal pigs are: strong breeding ability, strong limbs, good semen quality, high growth rate and lean meat percentage, and a large number of lean meats distributed in high economic value areas; heterozygous (Nn) can be allowed for halothane-sensitive genes.
Maternal pig breeding objectives: High fecundity, strong maternality; good appetite, moderate growth rate and lean meat percentage; no halothane-susceptible gene requires a genotype of NN.
Selection and selection of breeding herds
Breeding and selection of breeding pigs are two basic approaches to genetic improvement of herds.
Seed selection: The genetically superior individuals are selected to reproduce one generation, so that the average value of the next generation can be superior to the previous generation;
Matching: Avoiding the group's transitional inbreeding leads to in-dip recession, while increasing the opportunities for the next generation of extremely good individuals.
Seed selection: selection of reserve pigs adopts four stages:
1. Breastfeeding stage selection: nesting + selection.
2. Selection of end of nursery period: nesting + selection, at least one male and two females per litter, into individual performance measurements; selecting individuals with a robust body and no genetic defect in each litter.
3. Selection of end-of-measurement selection: selection, queuing according to the composite index, selecting the individual with the highest index; in addition, physical appearance evaluation is also required.
4. Selection of breeding and breeding stages: Individuals with good health and reproductive performance should be selected to participate in breeding if the comprehensive selection index of qualified breeding boars exceeds that of the previous generation of boars.
Matching: The selection of spare pigs includes: quality matching and kin selection.
Reserve pig selection
Four stages of selection methods are generally used: selection during the lactation phase, selection at the end of the conservation phase, selection at the end of the determination phase, selection of breeding and breeding stages.
First choice: breastfeeding stage selection (warm selection + selection)
The standard of selection
Changbai and Dabai sows: No less than 10-11 litters are born alive.
The Duroc sow litter produces 7-8 or more live pigs.
Sows were corrected to 21-day-old litter weight (lactation force) by actual parity, number of weaning days, and number of litter litters.
Changbai and White sows corrected 21-day-old litter weight no less than 55 kg.
Duroc corrected the weight of the 21-day-old litter to not less than 50 kg.
Selected criteria
In the litters satisfying the above conditions, piglets with healthy, lively, well-arranged and well-developed nipples (more than 6 pairs), no signs of loss in body appearance and high body weight were selected.
We select 2 male and 3 female piglets per litter at weaning.
Make a mark.
The original litter is cultivated or concentrated.
Second choice: selection at the end of childcare
Pick + choose:
At least 1 male and 2 females per litter enter the individual performance assay.
Individuals with large body size, robust body, and no genetic defects.
Third choice: determination of the end of the phase selection
Individual selection (standard: index + appearance)
According to the composite index, the highest index was selected.
Body appearance evaluation.
Fourth choice: selection of breeding and breeding stages
Selected criteria (health + reproductive performance):
Blood samples from boars and sows were kept for detection of pathogens such as swine fever and pseudorabies. Positive pigs did not stay.
The boar carries on the semen examination, does not pass the unqualified;
The sow does not stay in the race for two consecutive times;
When the index of comprehensive selection for eligible retained boars exceeds that of the previous generation of boars, they enter breeding herds and participate in breeding.
Breeding options
Random mating (ie mating between males and females completely random, regardless of their kinship and production performance as a benchmark) is divided into quality matching (property matching) and kin selection. The focus is different, but they are related.
Quality matching
According to the male and female sows’ production performance (measured by genetic evaluation results), selective mating is divided into homogenous matching and heterogeneous matching.
Homogeneous selection is to select a male and female pig of similar performance for mating
Heterogeneous selection is a sow with excellent performance in some respects and a poorly performing but better performing sow.
Affinity matching
If there is a relationship between the two parties, it is called inbreeding (inbreeding).
Consciously avoiding some degree of inbreeding, known as distant mating (outgoing).
Affinity can be measured by the coefficient of kinship. The sibling coefficient between full siblings was 0.5, the sibling coefficient between siblings was 0.25, and the kinship coefficient between parents and children was 0.5.
Offspring produced by inbreds are called inbred individuals.
The advantages and disadvantages of in-flight
Inbreeding is an effective and even necessary means for exposing harmful genes, maintaining good pedigrees, improving homogeneity of pig herds, fixing good traits, and cultivating experimental animals.
For most traits, especially those with lower heritability (eg litter size, number of weaned piglets, etc.), inbreeding causes inbreeding depression.
In the current improved breeding of lean bred pigs, due to the limited size of the population, inbreeding is often unavoidable, and it is necessary to control the inbred control within a certain range through matching.
Pigs rearing
The newly-introduced reserve pigs were isolated and the isolation period was about 45 days.
Vaccination. The gilts were injected with parvovirus and Japanese encephalitis 4 vaccine four weeks prior to their mating, 2 weeks prior to delivery, jaundice and pseudorabies vaccines were injected into the piglets, and 4 weeks before the replacement of the boar, parvovirus, swine fever, and erysipelas vaccines were injected.
Pay attention to breeding and management of breeding pigs, ensure normal estrus, ovulation, and conception of sows, increase breeding performance of breeding boars, pay attention to the health of pigs before and after mating, and pay attention to breeding techniques and pregnancy identification.
Ensure the normal estrus and ovulation of sows, ensure proper reproductive status, and provide short-term excellent feeding and aphrodisiac for sows. The gilt sow has a pubescent date of 200 days, a fitting age of 220 days to 240 days, an adapted weight of 120 kg to 140 kg, and a suitable sow of 18 mm to 20 mm. The short-term optimal feeding method is based on the lyrics, daily feed concentrates 2.7kg-3.2kg, 0.4%-0.7% animal fats added by weight. Poorly sow sows have obvious short-term effects.
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