How to breed goats for high productivity? A detailed explanation of the key technical points

1. Artificial insemination technology for goats

Artificial insemination technology refers to the method of using instruments to collect semen from a stud ram, processing and preserving it, and then using instruments to deliver the semen into the reproductive tract of a doe in estrus so that she conceives. Artificial insemination technology can rapidly expand the number of improved breeds and effectively increase the utilization rate of individual superior stud rams, and is one of the important technologies of modern animal husbandry. Artificial insemination technology for goats includes semen collection and processing, preservation, estrus identification, and timely insemination techniques.

1.1 Semen collection: The preparation of ram semen used for artificial insemination begins with the use of instruments to collect semen from the stud ram; at present, the artificial vagina method is mostly used for semen collection.

1.2 Ram training: Rams used for semen collection should undergo about one month of training before formal collection, including observing mature rams collecting semen, becoming familiar with the teaser animal, the semen collector, and the collection procedure. Rams selected for semen collection are generally 1 to 5 years old; collecting semen too early can easily cause damage to the ram, affect its growth, and shorten its breeding service life.

1.3 Preparation before semen collection: Before collecting semen, the instruments must be strictly disinfected. The preparation of the artificial vagina requires that temperature, pressure, and lubrication all reach suitable levels. Generally, the prepared artificial vagina should have a temperature of 38°C-42°C, pressure such that the inner liner is filled to form a triangle, and lubrication such that lubricant is applied to the inner third of the inner liner from the outer opening inward.

1.4 Semen collection procedure: During collection, at the moment the ram mounts the teaser animal, the prepared artificial vagina is used to guide the extended penis into the artificial vagina so that it ejaculates inside, thereby obtaining semen.

1.5 Semen dilution and preservation: The collected semen should immediately be examined for quality under a microscope; after determining the dilution ratio, it should be diluted immediately at equal temperature and then transferred to low-temperature preservation. Because artificial insemination of does uses cervical insemination, the dilution factor after semen collection should not be too high, and is generally 3-5 times. At the same time, to ensure successful mating, the semen used for insemination is required to have motility of no less than 0.5. This determines that goat semen preservation methods are mainly room-temperature dilution with immediate mating and low-temperature preservation with mating within 1 week, and that large-scale promotion of frozen semen artificial insemination is not suitable (except for breed conservation or introduction of rare breeds).

1.6 Estrus identification: The estrus of does differs from that of other livestock; the signs are not obvious and are not easy to detect through external observation, so the ram teaser method is commonly used to determine estrus. The method is: wrap and tie a teaser cloth around the ram's lower abdomen to ensure the ram's penis cannot extend to perform mating behavior, then release it into the doe flock so that by smelling the vaginal odor of does and attempting to mount, it searches for does in estrus. During teasing, the small-pen teasing method should be used, which helps save the energy of the teaser ram and reduces excessive stress in does caused by chasing by the ram. Standing still when mounted by the ram is a prominent sign that a doe is in estrus.

1.7 Timely insemination: For does in estrus, generally at the same time estrus is confirmed, natural mating is used, or artificial insemination is performed once after 6-8 h, followed by another insemination at an interval of 8-12 h. In production, the method commonly used is mating in the evening for does that come into estrus in the morning, and mating in the early morning for does that come into estrus in the afternoon. For does subjected to estrus synchronization treatment through estrus control technology, ram teasing may be omitted, and insemination can be performed simultaneously directly 42 h after drug treatment is stopped, followed by another insemination at an interval of 8 h.

1.8 Artificial insemination: Artificial insemination of sheep mainly uses the vaginal speculum method or the vaginal endoscope method. The method is: insert a vaginal speculum or vaginal endoscope into the doe's vagina, use a reflector or flashlight beam to locate the external opening of the cervix, insert the loaded semen insemination device 1-2 cm into the external opening of the cervix, inject the semen, and then gently and slowly withdraw the insemination device and vaginal speculum.

2. Early pregnancy diagnosis technology for does

In early pregnancy (1 d-90 d), the placenta of does is not firmly attached and miscarriage is likely to occur. Early pregnancy diagnosis helps strengthen the management of pregnant does, reduce miscarriage in pregnant does, and improve the reproductive efficiency of does. In early pregnancy, the body shape of does does not change obviously and is not easy to confirm through external observation. At present, the main diagnostic methods are mainly the estrus observation method and the B-ultrasound detection method.

2.1 Estrus observation method: The estrus observation method determines pregnancy in reverse by observing estrus. Generally, around 20 d and 40 d after mating, teasing is carried out continuously for 3-5 d each time. Mated does that show no estrus on two consecutive occasions are confirmed as pregnant does. Advantages: simple to perform and does not require instruments. Disadvantages: the earliest confirmation time is relatively late, requiring two consecutive estrous cycles after mating (about 40 d); only does that do not show estrus can be confirmed pregnant. In addition, because some does may still show estrus after conceiving, they are easily misdiagnosed as non-pregnant, resulting in repeat mating and even miscarriage due to chasing, mounting, or butting by rams.

2.2 B-ultrasound detection method: This refers to the method of confirming pregnancy by using a B-mode ultrasound device to probe the fetal development in the uterus through the abdominal wall or rectum of mated does. Advantages: relatively little stress to does, and the detection results are intuitive and accurate, and the time to confirm pregnancy is also earlier than the teasing method. Generally, pregnancy can be confirmed around 30 d after mating by finding the gestational sac, with an accuracy rate of more than 80%; around 40 d after mating, pregnancy can be confirmed by finding cotyledon development, with an accuracy rate of 100%; around 50 d after mating, the twinning rate can be further determined by observing the fetus; experienced examiners can confirm pregnancy as early as around 18 d after mating. Disadvantages: handheld instrument use and early detection technology require some experience; for small sheep farms, because the frequency of use is low, the cost of using the instrument is relatively high.

3. High-frequency breeding system for does

3.1 Three lambings in two years: Each doe gives birth once every 8 months, so exactly 3 lambings occur in two years. This system is generally described as a fixed mating and lambing plan: lambs are generally weaned at 2 months, and does are mated 1 month after the lambs are weaned. To achieve the goals of balanced lambing throughout the year and scientific management, in production the flock can be divided into 4 groups whose 8-month lambing intervals are staggered, so that every 2 months there is 1 batch of lambs for slaughter and market.

3.2 Five lambings in three years: Because half of a doe's gestation period is 73 days, which is exactly 1/5 of a year. The flock can be divided into 3 groups. When the system begins, group 1 does lamb in period 1, are mated in period 2, lamb in period 4, and are mated again in period 5; group 2 does lamb in period 2, are mated in period 3, lamb in period 5, and are mated again in period 1; group 3 does lamb in period 3, are mated in period 4, lamb in period 1, and are mated again in period 2. Repeating this cycle, the lambing interval is 7.2 months. For does producing 1 lamb per litter, 1.67 lambs can be obtained per year; if 2 lambs are produced per litter, 3.34 lambs can be obtained.