The key technology of producing high quality fat lamb

The high-quality fat lamb refers to the lamb whose body weight reaches 35~40kg after being weaned at 2-3 months and fattening at 4-6 months after crossing with local breeds. Compared with the traditional feeding method, the breeding cycle is shorter, the input of feed is less, and the production rate, meat yield, commodity rate and meat quality are improved, which is more conducive to the organization of professional and intensive production. Since 2009, Yanggu County has undertaken the project of popularizing the production technology of high-quality fat lambs in Shandong Province for several years in a row. Through the implementation of the project, it has promoted the technologies of economic hybridization, synchronous estrus, artificial insemination and centralized fattening to produce high-quality fat lambs. Obvious economic benefits have been achieved. The key technical measures are summarized as follows:

1 Economic hybrid technology

The introduced high quality mutton sheep breeds were selected as the male parent and the local small tail Han sheep as the female parent for economic crossbreeding, and all the hybrid offspring were used in the production of fat lambs. The hybrid generation has the advantages of strong vitality, rapid growth and development, high feed utilization rate, neat product specifications, good meat quality and so on.

1.1 main points for the selection of male parents: (1) select varieties with good production performance and stable heritability of various traits; (2) select varieties with rapid early development, good meat quality and good meat shape; (3) choose varieties with rich breed resources and meet the requirements of fat lamb production of mutton sheep. After several years of practice, Yanggu County finally chose Dupo sheep as the hybrid male parent.

1.2 main points for the selection of female parents there are 3 key points for the selection of small-tailed Han sheep. (1) to select individuals with high fecundity, from those who had given birth to one child, to give priority to 2 or more lambs in the first birth, (2) to select individuals with strong lactation and good motherhood, and (3) to choose ewes with good physical condition (middle and upper fat).

2 estrus synchronization technique

Synchronous estrus is a technique that uses some hormones and drugs to synchronize the estrous cycle of ewes and artificially control a group of ewes to concentrate their estrus within a certain period of time. The application of estrus synchronization and artificial insemination technology can realize centralized breeding, lambing, fattening and fattening of sheep in production, realize the three yields of ewes in two years, reduce the labor intensity and improve the efficiency of breeding.

Selection of drugs and tools (1) CIDR vaginal suppository and CIDR gun were produced by former Pfizer Company of New Zealand; (2) gonadotropin of pregnant horse serum was produced by Ningbo Sansheng Pharmaceutical Co., Ltd.

(5) on the 12th day, the CIDR vaginal suppository was removed and the vagina was opened with an asphyxiator and washed with normal saline (4 million IU penicillin and 4 million IU streptomycin per 500ml). (6) at the same time, each sheep was injected with PMSG500IU. Generally, the sheep treated in 2d can be mated in estrus.

2.3Note (1) when using progesterone vaginal suppository, the effect of injection of pregnant horse serum gonadotropin (PMSG) is very good, but the cost is high. (2) in production practice, ewes with better physical condition should be selected as ewes for synchronous estrus, because the fatness of ewes directly affects the effect of synchronous estrus. (3) when injecting pregnant horse serum gonadotropin (PMSG), we should be very careful not to leave the drug in sheep. (4) according to the breeding ability of rams, the number of ewes should be handled every day, and the number of ewes in estrus should be controlled so that they can match in estrus.

3 artificial insemination technology

3.1 ewe estrus identification (1) ewes often show excitement, abnormal behavior, frequent tail swinging, sensitive to external stimuli, loss of appetite, mating desire, actively approach the ram, stand still when the ram chases or crawls; (2) vulva relaxation, congestion, swelling, clitoris erection; (3) vaginal congestion, relaxation, secretion of mucus; (4) estrus holding.

The duration is generally 36 to 60 hours, and the average estrous cycle is 21 days. (5) when the ewe terminates estrus, the ram is refused to approach and climb.

3.2 the ratio of ram to ewe in the trial is 1: 40: 50. After entering the ewe flock, the ram is found to be an ewe that stands still and actively approaches the ram or accepts the ram to climb across.

3.3 semen collection and dilution (1) semen collection: the semen collector crouched on the right side of the Taiyang sheep, holding the false vagina in his right hand at an angle of 35 degrees 40 degrees with the ground, close to the rump of the Taiyang sheep, when the breeder ram climbed on the back of the Taiyang sheep and protruded the penis, the semen collector nimbly supported the penis foreskin with his left finger and introduced the penis into the false vagina. Immediately after the ram ejaculates, the false vagina is erected to remove air.

The next semen cup, cover the semen cup, hang the ram brand to send to the semen processing room, the ejaculation volume of the ram is generally 1: 1.5 ml; (2) semen quality examination: normal sheep semen is milky white, tasteless or slightly fishy (with rotten smell, red or brown semen is not available); take out the original semen or semen diluted with normal saline 1 drop, magnify under the microscope 300 times 600 times to observe sperm viability and density. (3) dilution of semen: milk diluent was taken from fresh milk of healthy cows and ewes, disinfected 15min in water bath (92-95 ℃), cooled to less than 40 ℃, and added penicillin 100-200,000 IU / 100ml.

Egg diluent (glucose 3G, sodium citrate 1.4g, distilled water added to 100ml). Take the supernatant 80ml, add yolk 20ml penicillin 100000 IU; normal saline (0.85% sodium chloride solution), the dilution multiple should depend on the semen density, viability and the selected diluent, each insemination dose 0.1~0.2ml, keep the effective sperm count above 20 million.

3.4 semen preservation and transportation (1) the semen collected should be quickly diluted, packed and cooled after passing the quality inspection, and the thermos for transporting semen should be put into ice to keep the semen temperature at 2: 5 ℃ and strictly prevent severe oscillation; (2) take out the thermos during insemination and raise the semen temperature to 18 ℃ at room temperature (warm water) (3) the semen transported and preserved need to pass the semen quality test before it can be used for insemination.

Insemination time (1) insemination time: ewes must undergo estrus identification and health examination before insemination is allowed. Insemination time is usually 12-24 hours after estrus; (2) insemination site: clean the vulva, gently insert the sterilized opener into the vagina, open the vagina, look for the external orifice of the cervix, and then insert the insemination device into the external orifice of the cervix, with a depth of about 1~2cm.