Zotc111 LE 2

• Reproduction is the process by which animals produce offspring.
• Reproductive decisions are some of the most critical management decisions that a producer makes.
• The ability to reproduce is one of the basic characteristics of a living thing; in order for a species to continue they must be able to produce viable offspring.
• Parents are selected and mated to achieve certain goals with offspring such as producing offspring with high milk productivity, large litters, or meaty carcasses.
• Advantages of MOET include more offspring from outstanding females, opportunity to test males genetically, for carrying undesirable traits, and facilitates transport of genetic resources.
• Producers now have the ability to use sexed semen.
• Sexed semen is semen that contains only all male or all female sperm.
• There is only about a 90% chance that the preferred sex will be produced and the cost of the semen is much higher.
• Reproduction results in new animals that are raised for the products they produce, examples of products include meat, eggs, milk, wool, and pets.
• Sexual Reproduction is the production of offspring by the fusion of haploid gametes (eggs & sperm) from two parents to form a diploid zygote (fertilized egg).
• Genetic variability is increased by the random combinations of genes from the parents.
• Testes are where male gametes, sperm cells, are produced.
• Testes contain the seminiferous tubules where sperm are formed.
• Leydig cells scattered between the tubules produce testosterone & other androgens.
• Sperm production can’t occur at normal body temperature in mammals, so the testes are held outside the body in the scrotum.
• After leaving the testes, sperm pass through the epididymis where they become motile and gain the ability to fertilize an egg.
• Sperm leave the body through the vas deferens and urethra.
• An orgasm occurs as rhythmic muscular contractions compress the urethra and expel the semen, this expulsion is termed ejaculation.
• The accessory sex glands provide 95-98% of total ejaculate volume: the prostate gland produces a secretion that buffers the vaginal pH, which is normally 3.5 to 4, the seminal vesicles add fructose to nourish the sperm and prostaglandins to promote contractions in the female, and the bulbourethral gland (cowpers gland) produces mucus which lubricates the penis to help dilute the concentration of sperm & provide a suitable environment for them once it buffers the vaginal pH.
• The production of spermatozoa which occurs in the seminiferous tubule is called as spermatogenesis.
• The conversion of the spermatids into spermatozoa is called as spermiogenesis.
• The release of the spermatazoon into the lumen of the seminiferous tubule is called spermiation.
• Certain physical handicaps to mating can be overcome.
• Sire cost can be reduced.
• The danger and cost of keeping a sire can be eliminated.
• The cost and delays involved in using infertile sires can be reduced.
• Better health can be maintained.
• Breeding herd records can be improved.
• Profits can be increased.
• Limitations of AI include the potential to spread diseases easily if improperly used, spread poor genes very rapidly if sire used is of poor genetic quality, lower reproductive efficiency rate than that of natural mating, expensive equipment and supplies used in AI work, and need for well trained technicians to carry on the work.
• In cattle, collected semen is processed by diluting it (semen extender) and slow freezing in “french” straws.
• Heat detection is very important in cattle as failure to detect it is a major cause of prolonged calving intervals.
• Thawed semen from the plastic straw is directly deposited into the female reproductive tract to ensure that the maximum number of live sperm will be inseminated in the process.
• Estrus Synchronization involves treating animals with a drug-prostaglandin or its analogs, to reset their reproductive clocks, enabling them to come into heat all at the same time.
• Prostaglandin F2 alpha is injected twice, 10-11 days apart in cows, causing all the cows to exhibit estrus 48-72 hours after the last treatment.
• Progestins, similar to progesterone, prevents estrus and maintains diestrus stage, are administered by injection or implants, causing all females to start their proestrus period 12-15 days after administration.
• Multiple Ovulation (Superovulation) involves injecting a dam with superior genetic characteristics with a hormone to cause superovulation, through AI, the eggs are fertilized by semen from a genetically superior sire, and the superovulated dam develops a number of fertilized embryos that is later harvested into the uterus.
• Embryo Splitting involves using a microscopic surgical blade to puncture the zona pellucida of the embryo and cut it into half, commonly applied to large domestic animals to increase the number of offspring with identical genotypes, based on the principle of twins wherein identical twins are produced from the natural splitting of the embryo producing two identical offspring.
• Embryo Transfer/ Transplant involves the removal or collection of an embryo in its early stage of development from its own mother’s reproductive tract and transferring to another female’s reproductive tract for development to term.
• Capacitation is the final maturation of the spermatazoon which occurs in the female genital tract.