Sheep - AgRIS

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7. 2 Types of breeding <strong>Sheep</strong> are bred either by natural mating or through artificial breeding. Rams of the Indigenous breeds donate good quality semen under proper management conditions throughout the year. However the rams oftemperate breeds if not protected from high temperateure, high humidity and high solar radiation will not produce good quality semen during hot dry and hot humid seasons. Females oftropical breeds cycle throughout the year. Temperate breeds which are affected by hours of day light, breed with declining day length. They came in heat in autumn from August to November, although some may breed up to February. 7. 2.1 Natural Breeding The natural breeding is done either by flock mating, per mating and hand mating. In flock mating system>/8heep can be bred naturally or through artificial insemination. The natural breeding is done by either flock mating, pen mating or hand mating. In flock-mating system, breeding rams are usually turned out in the flock during the mating season at the rate of 2 to 3 per cent of the ewes all through day and night. It is most widely practised in the flocks of all farmers. Semi flock breeding or pen breeding is done to conserve the energy of rams and give them rest. In this, the rams are turned out for service with the flock in the pen during night, and confined and stall-fed or grazed separately during the day time. Hand mating is practised when exotic purebred sires are used, or when it is considered desirable to extend the services of ram over much larger flocks. <strong>Sheep</strong> in heat do not manifest behavoioural symptoms. Hence, the teaser rams are employed for detecting the ewes in heat. These ewes are then taken out of the flocks and bred to the designated sire of the flock. In pen and hand-mating systems and when teaser rams are used for heat detection some dye mixed in grease or simple linseed oil is smeared on the brisket of the ram. This makes it possible to record the date when the ewes is bred and also to remove them from the breeding flock. The colour of the dye should be changed every 16 to 18 days so that the repeaters can be discovered, if the bred ewes have not been removed from the flock. This is termed as marking of ewes by breeding ram and marked ewes are considered as bred. Breeding rams are usually turned out in the flock during the mating season at the rate of 2 to 3 per cent of the ewes all through day and night. It is most widely practised in the flocks of all farmers. 7. 2.2 Artificial insemination From four to eight ewes may be inseminated from one service of a ram—although as many as 30 to 40 have been reported, 0.1 to 0.2 cc of semen is sufficient for the purpose when there is a heavy concentration of sperm in the semen. Great numbers of sperm are of course needed as they are microscopic in size, and the reproductive tract of the female through which they must migrate to come in contact with the egg, also microscopic, is very large indeed in relation to the size of the reproductive cells. Apparently, most sperm do not survive more than 18 to 24 hours in the reproduction tract of the ewe. Russian research workers have reported impregnating from 300 to 400 ewes in one season with the semen collected from a single ram. They also reported that 90 percent of the ewes so insemianted became pregnant. This is a far greater number than could be bred to one ram using natural methods. From 40 to 60 ewes is generally considered a reasonable for a ram in one season. For the purpose of artificial insemination, artificial vaginas are used for the collection of the semen, although it may be recovered in some quanitity from the vagina of an ewe. Semen can be preserved for several days with suitable media and low temperature and has been transported long distances and used successfully in experimental tests. The semen is diluted for use and is injected into the vagina or deposited at the base of the cervix through a glass or plastic tube. Two inseminations at about a 12 hour interval, beginning soon after the onset of heat, are often recommended. Although little use has been made of artificial insemination in sheep except in an experimental way, some of the advantages and disadvantages are known. The chief advantages are: the usefulness of a superior sire may be extended; the number of rams needed for a large flock is reduced, and a flock of considerably greater uniformity should result. Disadvantages include the need for extra equipment and labor, some of which must be skilled in the work the 399
need for one or more "teasers" to detect which ewes are in estrus, and the frequent handling of the ewes during the breeding season. 7 2. 2.1 Puberty Puberty in the males is marked by production of viable sperms and a desire for mating influenced by hormone testosterone. The age at puberty vary from 132 days for Tobasco (Pelibucy) x Dorset lambs on the high plane of nutrition in Mexico (Valecia et al., 1977)to as old as 738 days for 3/4 Rambouillet 1/4 Malpura lambs in Rajasthan (Tiwari and Sahni 1981). The quantity and quality of ejaculates collected from puberscent rams are poor with a high incidence of dead and deformed sper natozoa (EL-Wishy, 1974). Ram lambs reach puberty about two months earlier than ewe larnbs in each breed. Age at puberty depends upon the nutrition of lamb. Some breeders allow gimmers to mate immediately after they attain puberty. There is no evidence that early first lambing results in diminshed reproductive capacity (Wilson and Durkin, 1983). The hormonal stimulation of lambs is of practical use in the tropics. The gonads of prepubertal sheep respond to exogenous hormones, but animals stimulated in this way do not commence spontaneous estrous cycle (Hunter, 1980). 7. 2.2.2 Ram Semen Collection Ram Semen can be collected by making use of (i) An Anoestrus ewe (ii) Artificial vagina (iii) by Electrical stimulation. i) Anoestrus ewe In this method the rams are trained to serve anoestrus ewe and after the service the semen is aspirated from the vagina. It is unsafe to use the semen so collected for fear of contamination. ii) Artificial vagina (A. V.) The pattern of A.V. is similar to that in the cattle, except that the A.V. is short. The outer hard rubber casing is 15.0 x 3.75 cm. The A.V. is prepared in the usual way by pouring hot water (45°C) through the inlet on the outer jacket. Necessary air is blown to provide cushioning affect and air valve tightened. Both the temperature and pressure are important. When the A.V. is ready, the inner temperature should be 40°C. Kaushish and Sahni (1976) considered it advisable to warrn the A.V. first with hot water (47°-50°V) initially and then pour out and refill the A.V. with hot water at 45° to 47°C, depending upon the season, in order to maintain the inner tube temperature between 40° - 41°C at the time of collection. A rubber cone is attached to one end of the A.V. at the end of which a graduated 5 ml test tube is fitted to serve as a receptacle for the semen. The open end of the A.V. should be properly lubricated preferably with liquid parafin. A glass collection cup may be directly fixed to the other end of the A.V. to obtain collection. Rams are very sensitive to temperature variations and therefore, adjusting, proper temperature in the A.V. is important. Once the rams are exposed either to an A.V. which is too hot or cold, they may refuse to serve on subsequent occasions. A freshly prepared artificial vagina should be used for each collection from a ram to avoid contamination. It should be properly sterilised aRer the use and kept in dry sterile chamber ready for use. iii) Electrical stimulation The equipment for collection of semen from the rams by electrical stimulation as modified by Dziuk et al., (1954) is said to be satisfactory. The power is obtained from 110 volt battery with 60 cycles which is reduced by transformer to 3 0 volt. This isolates the electrodes from the line of source. The probe for insertion into rectum is made up of rubber hose about 3/4 inch diameter with shoulder rings one inch apart. Alternate rings or electrodes are connected to provide the difference in electrical potential between adjacent electrodes. With this equipment the collection can be made in standing position. However, at times it is necessary to restrain the 400
Page 1 and 2:
1. Introduction ANNEXURE - IX-C SHE
Page 3 and 4:
2. Classification, Origin and Domes
Page 5 and 6:
Nadu, Andhra Pradesh and Karnataka,
Page 7 and 8:
different states it is estimated th
Page 9 and 10:
Table 3.3 continued...... Country N
Page 11 and 12:
een possible because of its substan
Page 13 and 14: (USA). The Rambouillet as purebreds
Page 15 and 16: ii) Marwari Deriving its name from
Page 17 and 18: Pradesh and Bihar, Bijapur, Gulbarg
Page 19 and 20: elatively tall with little hair exc
Page 21 and 22: 4.2 Distribution of type breeds in
Page 23 and 24: Table 4.1 continued...... Region/Br
Page 25 and 26: Table 4.2 continued....... SI. Bree
Page 27 and 28: 5. Genetics 5.1 Chromosome Profile
Page 29 and 30: esponsible for the formation of one
Page 31 and 32: the exercise these animals did not
Page 33 and 34: For understanding the inheritance o
Page 35 and 36: with a dense growth of relatively l
Page 37 and 38: produced on rations which contain i
Page 39 and 40: The Coefficient of Variation The co
Page 41 and 42: 5.6.3 Wool Production/Wool yield an
Page 43 and 44: 6. Breeding 6.1 Components of Sheep
Page 45 and 46: elationships. Certain coat colors a
Page 47 and 48: Selection on this basis means that
Page 49 and 50: ii) Independent Culling Method In t
Page 51 and 52: eflected by increase in average fle
Page 53 and 54: at 75 or 8-4 monthly intervals comp
Page 55 and 56: Based on the crossbreeding results,
Page 57 and 58: Table 6.8 Means and standard errors
Page 59 and 60: month post-weaning individual feedl
Page 61 and 62: ams) in November, 1975 for evaluati
Page 63: een heavily fed and therefore may h
Page 67 and 68: ii) Consistency The normal consiste
Page 69 and 70: collection frequencies per day in 3
Page 71 and 72: iv) Altitude High altitude and poor
Page 73 and 74: containing diluents enriched with a
Page 75 and 76: 6. Nutrients Although spermatozoa u
Page 77 and 78: 7. 3.1 Puberty Puberty in the femal
Page 79 and 80: Estrogen in large quantities inhibi
Page 81 and 82: The udder becomes firm and enlarged
Page 83 and 84: 7. 3. 8 Interlambing interval It is
Page 85 and 86: 8. Nutrition 8.1 Components of Shee
Page 87 and 88: allied to the various amino acids o
Page 89 and 90: animals. A deficiency of salt is sh
Page 91 and 92: seem to have most significance in s
Page 93 and 94: Table 8.2 Chemical composition of g
Page 95 and 96: Table 8.3 Nutritive value of fodder
Page 97 and 98: Mineral and vitamin Requirement If
Page 99 and 100: Table 8.5 Total digestible nutrient
Page 101 and 102: Table 8.7 continued....... c) Lacta
Page 103 and 104: shirinking due to reclaimation of l
Page 105 and 106: Sorghum-Berseem-Maize Improved vari
Page 107 and 108: 9. Housing and Management 9.1 Syste
Page 109 and 110: ) Shearing, skirtng and primary cla
Page 111 and 112: The availability of pastures which
Page 113 and 114: fodder as green or hay, concentrate
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9.2.2 Lambs Efforts should be made
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Mortality in young lambs and other
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land and they depend on the forest
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age and fed intensively till they a
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Overnight teasing and drafting ridd
Page 125 and 126:
The secretion of milk takes place d
Page 127 and 128:
with coarse and hairy breeds showed
Page 129 and 130:
11. Sheep Production System in Diff
Page 131 and 132:
12. Wool Production and quality 12.
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crosses with Dorset and Merinos, Pa
Page 135 and 136:
13. Meat Production 13.1 MeatProduc
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Table 13.1 Mutton (sheep) productio
Page 139 and 140:
14.4 Utilization of milk Sheep are
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one crushing mills and about 360 bo
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16. Sheep Records It is essential t
Page 145 and 146:
17. Diseases and their Control Morb
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Atropin sulphate 2.0 mg/kg. body we
Page 149 and 150:
contents by neutralization tests wi
Page 151 and 152:
prophylactic, foot and mouth vaccin
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Sheep - AgRIS

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