Sheep - AgRIS

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1. Sire individuality The spermatozoa from all apparently healthy rams do not stand the cold shock, therefore rams have to be screened for this attribute and selected for donating semen for freezing. 2. Extenders Neat semen can not be frozen and revived, it requires certain additives like nutrients, cryoprotectants, cell wall fortifying agents, buffers and antibacterial agents etc. to be provided. Semen has to be diluted to ensure the required number of spermatozoa per insemination dose to avoid wastage and to be able to cover more females from one ejeculate. Different workers have developed a nurnber of extenders using different combination of various chemicals having qualities of a good extender but with varying results of conception rate. A good extender should consist of following: 1. Buffering agents Ram semen has high number of vigorously motile spermatozoa which consume nutrients very quickly, collect the metabotites specially of the anaerobic respiratory pathway like lactate, pyruvate and lower the pH. Low pH disturbs the electric potential of the sperm cell wall leading to seepage of the enzymes and other material from within the spermatozoa and preventing some from entering into their body, causing toxicity, bursting of the cells and autolysis. To check this, it is important ot provide suitable buffering material which may not allow the pH to go down drastically and keep it within the tolerable range. Alternatley certain chemicals like cortisole and catalase etc which may avoid accumulation of lactate, pyruvate, H 2 O 2 if provided may give good results. Milk has good buffering capacity but the results in the freezing experiments are not satisfactory. Egg yolk, blood serum albumin and different chemical buffers like tris, glycine, citrate, phosphate etc have given good results. Out of these egg yolk and tris have not become popular. Although electrolytes are helpful at the time of thawing they are unwanted at the time of freezing. 2. Cryoprotactants Spermatozoa contain some water. On freezing, the volume of frozen semen expands resulting in the bursting of spermatozoa cells and killing them. Cryoprotactants decrease the freezing point below zero degree celsius, allow the water to make smaller crystals and the chance to pass through the stage quickly. Glycerol, DMSO, ethylene glycol and propylene glycol have been used but varying percentage of glycerol has found favour with most of workers. Its higher percentage is harmful because it is reported to deplete the ATP, the energy reserves of the spermatozoa. Cyroprotactants need some time to enter the sperm cell. It is called "equilibration time". Equilibration time of 1 h and 30 min have been tried but best results have been reported with 1, 4 and 5 h at 4-5°C temprature. Some workers have different opinion. It must, however be taken care that the cabinet temperature does not go below 2°C during equilibration. 3. Cell wall fortificatton agents Egg yolk, egg yolk extract, lecithin, glutathione have been comrnonly used. 4. Antioxidants Ram sperm cell wall lipids are oxidised quickly on coming in contact with oxygen in the medium or atmosphere, and lower the fertilizing ability. Alphatocopherol, BHT, etc have been used for the purpose. Boiling water just immediately before preparing the buffers also helps in removing free oxygen dissolved in it. 5. Osmoregulators Living cells perform well in the media isotonic to the biological fluid they are used to. They should perform well in extender isotonic to semen plasma although certain workers have claimed better results with slightly hypertonic diluents. 409
6. Nutrients Although spermatozoa utilize fructose and glucose in order of priority but maltose, raffinose, lactose, trebalose have given better results in freezing experiments. 7. Antibacterial agents Bacteria are practically omnipresent. Spermatozoa like the living cells, have to be kept away from bacteria and be controlled by providing suitable bactericides antibiotics. 8. Dilution rate It includes the number of live normal spermatozoa to be in- cluded per ml of the diluted semen per insemination dose while freezing in straws. Normally ram semen contains 3000- 5000 million sperms per ml of the neat semen and only 100-150 million sperms are enough to impregnate an ewteven though only one spermatozoa takes part in fertilization process. In certain extenders used for freezing, dilution rates of 1:2 and 1:3 have given better results than dilution rate of 1:1 which is general practice for short term preservation or for imrnediate use. 9. Rate of heat exchange It is the most important factor which needs monitoring. It is important not only to control the rate of echange of heat at the time of cooling but also at the time of thawing revival. It is clarified by some workers that it should be equal in both the stages and certain workers prefer high rate of cooling as well as thawing i.e. using high temperature water bath. There is a critical zone oftemperature which is particularly harmful for the spermatozoa and the latter group in the absence of the knowledge of that zone advise the practice of fast rate of heat exchange. Now a days computer controlled programmable cooling and thawing cabinets are available and the day is not for offwhen the critical temperature zone will be identified and the measures to pass through it will be devised for successfully freezing the ram semen. Some workers have advised thawing the pelleted frozen semen in media like citrate solution others however, have found no difference between the results of thawing with or without the medium. Some prefer freezing pellets while the others prefer freezing in straws to give wider surface area for quicker heat exchange. Pellets are prepared by dropping 0.2 ml of diluted equilibrated semen in the smooth pits carved on the surface of plas tic tray floating on liquid nitrogen allowing it to freeze for 3-5 minutes, collecting the pellets into the goblets and lowering down into the liquid nitrogen for storage. Allowing the liquid nitrogen in direct contact or not has made no difference. Straws have to be filled in the clean cabinet atomosphere of 4-5°C temperature after equilibration, sealed, exposed to certain temperature below 0°C for a particular length of time and then only lowered into liquied nitrogen (-196°C) for storage. These days small size liquid nitrogen containers are also available for transporting smaller quantities of frozen semen. During thawing certain workers have claimed good results with as low temperature of water bath as 37°C, while some advise as high as 75°C. Similarly the time for exposure may be 10-15 seconds for straws while 1-2 minutes for pellets. 10. Additives Addition to the semen of certain chemicals like cortisol, amylase, glucoronidase which play part in longivity of the spermatozoa in the female reproductive tract and are reported to be deficit under stressful conditions in the tract and their varying concentration in the ram semen with season, individuality etc, chelating agents like EDTA are also under study to see their effects vis-a-vis fertility rate. The process of freezing adversely affects the survival of sper matozoa. It is dependent upon number of inter-related factors such as diluent composition, concentration of cryoprotectant, dilution rate, size of pellet or straw and rate of freezing or thawing. There are some problems in achieving desirable lambing rate with the use of frozen semen. Unlike other species, the complex anatomy of the ewe‘s cervix does not permit smooth passage for frozen thawed spermatozoa in the cervical canal. Concerted efforts are going on to improve the fertility of frozen semen by improving the procedures of ram semen freezing and to develop better insemination techniques for laparoscope 410
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1. Introduction ANNEXURE - IX-C SHE
Page 3 and 4:
2. Classification, Origin and Domes
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Nadu, Andhra Pradesh and Karnataka,
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different states it is estimated th
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Table 3.3 continued...... Country N
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een possible because of its substan
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(USA). The Rambouillet as purebreds
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ii) Marwari Deriving its name from
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Pradesh and Bihar, Bijapur, Gulbarg
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elatively tall with little hair exc
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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 and 64: een heavily fed and therefore may h
Page 65 and 66: need for one or more "teasers" to d
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: containing diluents enriched with a
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
Page 115 and 116: 9.2.2 Lambs Efforts should be made
Page 117 and 118: Mortality in young lambs and other
Page 119 and 120: land and they depend on the forest
Page 121 and 122: age and fed intensively till they a
Page 123 and 124: Overnight teasing and drafting ridd
Page 125 and 126:
The secretion of milk takes place d
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with coarse and hairy breeds showed
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11. Sheep Production System in Diff
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12. Wool Production and quality 12.
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crosses with Dorset and Merinos, Pa
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13. Meat Production 13.1 MeatProduc
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Table 13.1 Mutton (sheep) productio
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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
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17. Diseases and their Control Morb
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Atropin sulphate 2.0 mg/kg. body we
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contents by neutralization tests wi
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prophylactic, foot and mouth vaccin
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Sheep - AgRIS

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