LIVESTOCK IMPROVEMENT S STUDENT RESOURCE SERIES ARTIFICIAL BREEDING

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1 LIVESTOCK IMPROVEMENT S STUDENT RESOURCE SERIES ARTIFICIAL BREEDING Introduction This country s dairy industry is one of its biggest export earners. Profit in dairying is made from producing and selling milk from dairy cows. Before a cow can produce milk she must first get pregnant and give birth. Producing milk therefore calls for two basic things - getting cows in-calf (pregnant) and then feeding the cows well so they produce milk of the right quality and in the right quantity wanted by local and world markets. They also have to get in calf again so they can continue to produce milk for their owner and for the dairy industry. New Zealand dairy cows are largely fed on grass. They are pregnant for around 9 months. Traditionally most cows calve (give birth) in the late winter or early spring, generally between July and September, with those cows being milked through into autumn. In addition, some farmers choose to be winter milk farmers, calving their cows in the late summer and autumn to produce milk through the winter months. Cows are mated between one and three months after calving. They continue to calve each year for life, their first pregnancy generally happens when they are around 2 years old (when they are known as heifers). This site is about how New Zealand s 13,000 farmers get their 3.5 million cows in calf each year so they calve over a 10 week period. It s a tall order, achieved through artificial breeding. Livestock Improvement has led dairy herd improvement in New Zealand since the early 1900s. Today it is the country s largest artificial breeding company. Three out of every four cows in New Zealand are sired by a Livestock Improvement bull! Come on a voyage of discovery Get onboard and, over the following pages, learn how Livestock Improvement leads the field in herd improvement and creates wealth for pastoral dairy farmers. You ll be taken on a voyage of discovery from the purchase of one crop of young bull calves through to the widespread birth of their offspring some five or six years later. 1

2 You ll learn why and how artificial breeding was developed back in the 1930s, how artificial breeding bulls are selected and bred today and how their semen is collected and inseminated into cows. Whether you live in the city or the country you ll find this a fascinating voyage because every New Zealander benefits from a vibrant dairy industry and our industry is one of the most vital in the world because Livestock Improvement s artificial breeding service drives the rate of genetic gain (improvement) which means this year s cows will be better than their mothers. We all benefit from a strong dairy industry because of the revenue generated through the production of millions of litres of milk and sale of milk products. Let s begin. 2

3 Voyage itinerary On the following pages you ll visit several destinations Which term is right - artificial breeding or artificial insemination? History how and when artificial breeding began in New Zealand. Early research into artificial breeding What artificial breeding is how it works. First things first breeding elite bulls; overview of the way Livestock Improvement breeds its artificial breeding sires. A closer view of Livestock Improvement s progeny test programme The best team of bulls in the world Livestock Improvement s Premier Sires Bull management Semen collection Semen processing Semen technology Storage of semen Livestock Improvement s unique semen distribution and insemination network Livestock Improvement s Artificial Breeding Technicians Artificial insemination Quick facts Glossary of Terms 3

4 Which term is right artificial breeding or artificial insemination? The terms artificial insemination and artificial breeding refer to the same thing the collection of semen from a male and its placement in the reproductive tract of the female to cause pregnancy. Overseas the term artificial insemination (or AI) is used. Here in New Zealand, we use the term artificial breeding (or AB). History how and when artificial breeding began in New Zealand Artificial breeding began, in New Zealand, in the late 1940s. It was one of a number of methods being used to get more production from dairy cows. The other methods included herd testing (measuring the amount of milk produced by a cow and testing the components of that milk) and herd recording (recording the parentage and other traits of cows). The reason for artificial breeding was twofold bull management and improving cow production described in a sire survey conducted in 1936 which said that around 37% of bulls actually lowered milk production! Globally there was an urgency for artificial breeding to answer the problems caused by shortage of top sires and reproductive diseases that caused abortions. In those days, dairy farms carried bulls with a ratio of around 1 bull to every 25 cows. Herds were small, averaging around 60 to 80 cows, requiring 2 or 3 bulls for the spring mating period. Farmers experienced all sorts of problems running bulls from fighting between bulls competing for a cow s attention, to broken gates and fences, spread of disease (cattle can suffer sexually transmitted diseases which affect health and fertility) and bull fertility. With natural mating a farmer usually does not know how good (fertile) a bull is until his cows are checked for pregnancy and then it s usually too late meaning those cows will calve later than their herd mates the following calving season. (Farmers want their cows to calve within a concentrated period. Cows are pregnant for 9 months leaving only 3 months to get pregnant again if there are any delays during this 3 month period it puts the cow outside the optimum (best) calving pattern for the herd). In addition to the health and management problems associated with natural mating, farmers also had extra costs associated with purchasing or leasing bulls coupled with the cost of grazing them - taking grass from cows which could otherwise convert that grass into profit (milk). Not to mention personal risk to farmers from handling the occasional wild bull! Artificial breeding provided an answer to these problems with the added attraction of getting progeny (young stock) from some of the best bulls in the world. Not surprisingly, farmers were keen to make use of this new science which promised so much in terms of farm management and herd improvement. 4

5 Early research into artificial breeding In 1939 research into artificial breeding began in Ruakura, Hamilton funded by the NZ Dairy Board and led by Dr John James. This AB centre was the forerunner of today s Livestock Improvement Corporation. Livestock Improvement is the largest artificial breeding company in New Zealand. Its research and technologies have led the development of AB around the world and made the rate of genetic gain (improvement) that New Zealand enjoys which one of the highest in the world. What artificial breeding is how it works Artificial breeding, or AB, results in the semen from one bull with superior genes being inseminated into thousands of cows each year compared to a mere hundred if he was simply a herd bull, siring one calf from each cow in the herd each year by natural mating. Artificial breeding sires are bred from the best genetics from New Zealand and around the world and their use in New Zealand has, over the years, increased the profitability and productivity of dairy cows. One of New Zealand s most prominent scientists and researchers of cow production, Dr Colin Holmes of Massey University, has been quoted as saying you couldn t farm today with 1950s cows. This simple statement describes the efficiency improvements in genetic gain which have been made over the years through artificial breeding. ( Genetic gain is the result of breeding increasingly superior bulls to increasingly superior cows and can be measured by the increased milk production of these cows year after year). The rate of genetic gain is said to be worth 3 kilograms of milksolids per cow per year. A kilogram of milksolids is worth around $4 to the farmer, so each year there is increased value to the farmer of $12 per cow. On a national scale, the value of genetic gain is in the region of $30 million each year. This level of genetic gain, or improvement, in the national herd would not have happened without the widespread uptake of artificial breeding. First things first breeding elite bulls Artificial breeding bulls are amongst the most elite in the world, because their selection is so intensive. Overview of the way Livestock Improvement breeds its artificial breeding sires Livestock Improvement operates contract mating and progeny test programmes (to find our elite bulls) which identifies, breeds, selects and raises a team of bulls whose semen 5

6 is used in cows being milked on a variety of New Zealand farms. It s called progeny testing because the programme generates daughters of promising young bulls that are milked and tested for milk production and a number of other traits. These results identify around 15 to 20 bulls each year (from an initial intake of 300) which are found to be good enough to be Livestock Improvement artificial breeding sires. A closer view of Livestock Improvement s progeny test programme Livestock Improvement s progeny test programme, known as the Sire Proving Scheme (or SPS) began in Today it is one of the largest progeny test schemes in the world. Each year, Livestock Improvement uses to its computer database to identify the top 3000 cows in New Zealand s national herd of around 3,500,000 cows. (Livestock Improvement s database is similar to the Births Deaths and Marriages Register for humans, recording all cow births, matings, deaths and production records since records began more than 25 million records in all!) If all the information in Livestock Improvement s computer database was printed onto A4 paper there would be a mountain of paper taller than Mt Everest! The top cows are identified by a genetic ranking called a Breeding Worth (BW). The better the cow the higher her breeding worth. The production records of these 3000 cows are scrutinised by Livestock Improvement s Livestock Selection team and the list is trimmed to around 900 of the most elite cows. These cows are then inspected by the team which checks for all the attributes Livestock Improvement wants from bull mothers eg conformation which enables her to calve easily each year so she will last several years in a commercial pastoral herd, good udder attachment (meaning the udder is well attached to cow s body and has a good shape so the milking machine sits evenly on each teat when she is being milked) and capacity (the udder is able to hold a quantity of milk), ability to forage (eat) good feet so she can walk long distances (there is often a long distance to walk between the paddock and the farm dairy where she is milked) milking speed (ability to let her milk down quickly when the milking machine is attached to her udder), and good temperament. The inspection usually sees the original list of 900 cows whittled down to 400. Specially selected yearling and heifers are then added to the list, making a total of 650 cows. 6

7 The farmer owners of these cows are then contacted by Livestock Improvement to see if they are interested in their cows becoming potential bull mothers (that is being mated to top bulls in the hope that the pregnancy will produce a bull calf good enough to be a future artificial breeding sire). If the farmers agree they sign a contract which says that Livestock Improvement will provide the semen for the mating and will buy the resulting calf if it s a bull. If it s a female (heifer) calf, that s the farmer s good luck and he/she keeps it. The following year, when these cows calve, Livestock Improvement representatives go to the farms and inspect the bull calves. Provided these three month old calves meet strict conformation requirements disease testing genetic defect testing and confirmation of their parentage they are purchased and transported to Livestock Improvement s farms where they are raised. Around 400 bull calves are purchased each year. These young calves spend their first year of life eating and growing. They are also trained to wear a halter and allow themselves to be led and handled. Over the year some are discarded from the team through a number of factors, like temperament, a change in the Breeding Worth of their parents, or failing health tests. The makeup of the final 300 yearlings to be progeny tested reflects farmer demand for the various breeds Holstein Friesians (black and white), 90 Jerseys and 60 KiwiCross (a mix (crossbred) of the popular breeds Holstein Friesian, Jersey, Ayrshire). Semen is taken from these young bulls and sent to Livestock Improvement s 700 Sire Proving Herds. Sire Proving Herds are specially selected because the farmers are very good record keepers, are committed to improving the genetic gain of the national herd and represent a range of farms across all the types of land found in New Zealand. The reason herds are spread around New Zealand is to generate information about cow performance on all types of farms from the top of the North Island to the bottom of the South Island and in between. The semen from these young bulls is inseminated into the cows in these Sire Proving Herds, and the heifer calves (born nine months later) are mated (at one year of age) and become milking cows when they are 2 years old. These cows (around 22,000 of them) are milked and their production results, combined with a variety of data including Milk production (protein and fat content and volume), Calving ease (cows that become pregnant and calve easily), 7

8 Traits Other than Production (TOP) which covers a range of physical standards that the cow must meet, such as the conformation of the udders whether the teats are evenly placed or too far apart, too high or low; the jaw position (cows have no top teeth so if their jaw is undershot they will have difficulty grazing) etc. Live-weight (the weight of the cow). All this data gets linked back to their sire hence the term sire proving. The data proves whether the bull is an elite bull or not. With all this information, Livestock Improvement can now identify around 15 to 20 truly elite bulls from the original 300 these are the bulls which go on to become a member of its elite team of artificial breeding bulls, known as Premier Sires. So of the original 300 bulls which entered the progeny test programme, around 270 will not make it into the team and are culled (sent to the meat works) at that point. The successful bulls which have made the grade and which become members of the Premier Sires team place pressure, of course, on current team members whose breeding worth must justify them remaining in the team. It s a bit like the All Blacks there s always pressure from up and coming talent! The best team of bulls in the world Livestock Improvement s Premier Sires. Premier Sires is an artificial breeding programme developed by Livestock Improvement as an economic, convenient and highly effective way for farmers to breed herds of high producing, easily managed, efficient cows which make money for their owners. Premier Sires is a team concept so each day, during the mating season, farmers receive semen from one bull from a team of bulls, as opposed to choosing semen from individual bulls. (The next day they will get semen from another bull in the team, and so on during the mating season). Livestock Improvement makes it easy for farmers by giving them a team of bulls which are genetically superior to anything available today; bulls specifically bred and selected for pastoral dairy farming. Livestock Improvement also provides an option for farmers to choose specific bulls to use randomly or to mate with certain cows: 8

9 Alpha Nominated is the Livestock Improvement brand with appeal to farmers who want to select bulls individually to tailor their breeding descisions. All Alpha Nominated semen is frozen, with the straws colour coded to depict the breed of the bull eg Holstein-Friesians have grey straws, Jersey green, Ayrshire blue and Hereford with brown straws. Livestock Improvement s Premier Sires team sires three out of every four dairy cows in New Zealand. The team contributes around $30 million dollars to the national economy each year and is estimated to have contributed more than 16 billion dollars to the New Zealand dairy industry and New Zealand economy since it began. Bull management When bulls become members of Livestock Improvement s elite artificial breeding teams they are tested for disease and then brought up to what is called centre status. That means they have passed all the health tests required to be able to export semen to overseas countries. When bulls are tested they get new a nose ring and swallow a magnet which stays in their stomach to attract foreign bodies (fencing staples, wire etc) that bulls sometimes eat by mistake and which (if undetected) would cause serious internal injury. Livestock Improvement bulls are kept outside for all their breeding life with a basic diet of grass. The only supplements to this diet are silage (grass cut in spring and stored in large covered stacks) fed during summer) and hay (grass, again cut in spring, but stored in bails to enhance its food value) (in winter). The bulls are tethered by a light chain from their nose-ring to an overhead wire. This means several bulls can be grazed, alongside each other but out of reach - in the same paddock. Bulls have to be kept separate to prevent them fighting with each other. The overhead wires also mean it is easy for the bulls to be loaded onto the bull cart (which resembles an open-top double-horse float, pulled by a tractor) for their ride to the semen collection barn. Bulls can graze, drink water from their own troughs, move about and rest in the shade using this system. 9

10 Great attention is paid to the safety, health and wellbeing of the bulls as only content, well-fed animals will produce significant quantities of semen. Each day during the peak of the season, and periodically during the rest of the year, the bulls are transported to the collection barn on the bull cart. Steers (castrated or vasectomised bulls known as teasers) are used to get the bull sexually aroused. (Cows are not used because of the potential for transmitting venereal disease). Semen collection Collections of semen are normally done in the morning with around two collections per bull per day every second day in the peak of the season, and one to two collections three times a week during winter. Bulls are allowed three loose mounts of the steer which means the bull mounts the steer but semen is not collected. The loose mounts emulate what would naturally happen in the wild when cows tease ardent bulls, often walking away several times before standing for mating. collected. Two staff members are required to collect semen from a bull. One controls the bull while the other holds a rubber device known as an artificial vagina. This is shaped and constructed to resemble, as closely as possible, a cow s vagina. The handler places this at the same angle as the bull s penis; the penis feels the artificial vagina and thrusts through to ejaculate; the semen is The semen goes into a test tube at the end of the artificial vagina. The quantity is immediately recorded and the vial labelled before it goes to the laboratory for processing. Semen processing Immediately the collection arrives in the laboratory it undergoes a series of international standard tests for sperm quantity, volume (number of live sperm) and quality (sperm of the correct shape and size. Sperm are very sensitive to changes in temperature and are slowly cooled to room temperature before they are stored in liquid or frozen straws. Information is printed on the straws giving the name of the bull, its official number, breed and the batch number of the ejaculate prior to the straw being filled. Semen technology Research into storage and lengthening the life of sperm so it can be used for artificial breeding began in the mid 1930s. In 1949 English scientist, Dr C Polge, discovered the 10

11 cryoprotective effect of glycerol, for the first time cooling and freezing sperm to 70 degrees C. Prior to this time artificial insemination trials had been going on in New Zealand (beginning in 1935) dealing with fresh semen but, because of problems collecting semen and inseminating cows, conception rates were low. In 1939 Dr John James (who qualified at the London Veterinary School in December 1937) began intensive study (and field trials) into artificial breeding concentrating on collection, dilution and storage of semen. By 1954, when Dr Pat Shannon started working for the artificial breeding centre (which was to become Livestock Improvement) around 25 million sperm were contained in each insemination. There had to be such a high number because sperm died off quickly when exposed to oxygen. The challenge for Pat and his team of researchers was to find out how to keep them alive longer and to dilute them further to get more inseminations from the best bulls. The answer was a diluent, now known as Long Last Liquid, which reduced the number of sperm per insemination from 25 million to 1-2 million sperm, without loss of fertility. The effect of that technology had a marked effect on the number of inseminations which could be collected from top bulls: In the 1950s bulls averaged 10,000 inseminations per year; Long Last Liquid meant Livestock Improvement could now get around 250,000 inseminations per bull per year! Livestock Improvement s Long Last Liquid (LLL) means the company is able to obtain more straws of semen per ejaculate than any other artificial breeding company in the world. Storage of semen Semen is stored in two forms frozen at very low temperature (196 degrees below zero) in liquid nitrogen. This temperature preserves the semen indefinitely. However because some sperm are inevitably damaged during the freezing process, a frozen straw contains more sperm than a straw of fresh (Long Last Liquid ) semen eg a frozen straw contains between 15 and 25 million sperm. To understand cryogenic damage, put a lettuce leaf in the freezer and then thaw it the next day. The cells are damaged by the ice crystal formation. The same thing happens to some sperm. 11

12 liquid (or fresh) via Long Last Liquid (LLL) which lasts for up to four days at room temperature without loss of fertility. The advantage of this method is that the sperm are not put through the severe processes of freezing and thawing. Because they are treated so gently, far fewer are needed for an insemination as fewer are damaged. A straw of LLL contains around 1.5 million sperm) The spring mating season in New Zealand begins in the first week of September. The semen collected from an Livestock Improvement bull in the morning can be tested, diluted and put into straws which will be inseminated on New Zealand farms later that same day. You ve learned how Livestock Improvement breeds the best sires of pastoral dairy cows in the world; how that semen is collected and processed and now you re about to learn how we get that semen out to farmers on the day it is collected! Livestock Improvement s unique semen distribution and insemination network. Part of Livestock Improvement s uniqueness in the international dairy industry is its integration the company s sire selection, breeding, semen collection and processing are integrated with its distribution and insemination network and on into its herd recording systems. Semen distribution Livestock Improvement s semen processing laboratories distribute straws of fresh or frozen semen. These straws of semen are packed in portable, insulated, liquid nitrogen containers which are transported (via the company s truck and van fleet) to central depots. Here they are picked-up by members of Livestock Improvement s Artificial Breeding team or do it yourself farmers farmers who are trained to do artificial insemination for their own herds. 12

13 There are around 1250 Livestock Improvement Artificial Breeding Technicians in New Zealand, supported by the company s sales force Regional and District Managers plus Sales Representatives. The sales force (in the early part of each year) visit every farmer in New Zealand to take their orders for the company s various services including artificial breeding. These orders are then supplied as straws of semen which have to be delivered to the farm so they can be inseminated into cows as those cows come into season (are fertile). It s a finely balanced act which takes place more than 3.5 million times each spring and, the following spring, delivers around 3.5 million calvings and a thriving dairy industry! Livestock Improvement s Artificial Breeding (AB) Technicians Many of Livestock Improvement s Artificial Breeding Technicians are dairy farmers who choose to work as a Technician for the 6-8 week mating period each spring as a way of supplementing their income and adding value to their local communities. Livestock Improvement s AB technicians are generally regarded to be the best in the business this is a result of their dedication and ability backed by the intensive training and monitoring programmes they undertake. Training is carried out on cows which have been culled from commercial herds (at meat works) enabling the technician to learn and refine the art of insemination and the complementary record keeping. Once they have successfully completed training, they are supervised in the field as they begin inseminating farmer s cows. The technical ability of an AB technician is evaluated by his/her supervisor and by what is known as the Non Return Rate that is the proportion of cows not returning to service (ie they are pregnant and don t need another service). Cows come into season (or heat) around a month after calving, and continue to come into season every three weeks until they are pregnant. Cows are normally mated on their second cycle or heat after calving, during spring. Artificial insemination Livestock Improvement s Artificial Breeding Technicians have defined customer groups and follow set routes each day so they can visit each farm on their group and inseminate cows which the farmers have identified as being ready for artificial insemination. The Technician calls at the farm where the cows are waiting in the 13

14 yard. After entering the cows details in a handheld computer (known as a DataMATE) the Technician selects the appropriate straw/s of semen. He/she will select the correct number of straws (one per cow to be artificially inseminated) the breed required the semen option ie Premier Sires (bulls from a high breeding worth team) or Nominated (individual high breeding worth bulls of a farmer s choice) A high degree of skill and knowledge is required in the next, most important, part of the AB Technician s role correctly inseminating the cow. The Technician s gloved left hand is inserted into the cow s rectum to locate the cervix and gently hold it in place through the bowel wall. He/she then uses his/her right hand to insert the inseminator (a long metal rod which contains the straw of semen) through the cow s cervix. Once the Technician is confident the inseminator is in the correct place, the semen is released into the cow s uterus. This procedure takes around 20 seconds per cow for an experienced AB Technician. 14

15 QUICK FACTS Three out of every four dairy cows being milked on New Zealand dairy farms are sired by a Livestock Improvement bull. Over 2.5 million dairy cows each year are now artificially inseminated with semen from the Premier Sires team. The present value of Premier Sires to the New Zealand dairy industry is assessed to be around 30 million dollars per year. In 46 years of operation the contribution of Livestock Improvement s bull teams to the New Zealand economy is estimated to be in the region of 16 billion dollars. More than 7,000 bulls have contributed to these milestones. The top bulls were able to be more extensively used because Livestock Improvement s discovery and development of Long Last Liquid (LLL) meant the sperm could last four days out in the field, so less of it was needed per dose of semen.. All the semen is frozen between December and June. Most of it is used for exports or stored for use by the AB Technicians in spring. A new breed, KiwiCross (crossbred bulls) has been introduced to the breeding options available from Livestock Improvement. KiwiCross bulls provide farmers with bulls whose parentage represents a cross between some of the best purebred bulls in the world. An insemination refers to a dose of semen deposited into a cow s uterus. An average collection of semen from a bull could produce a possible 600 straws of frozen semen. However, if it s processed into LLL semen it could have ten times that number of straws. The mean number of in-calf cows over 100 inseminations ranges from 55 to 65. A sperm will survive for about five minutes if exposed to air. A frozen straw contains about 15 to 25 million sperm because there is a higher die off rate when semen is frozen. A single sperm is 0.1mm long; its head is 8 microns by 5 microns. 15

16 About 4-5 mls of sperm is produced in one collection. The concentration of this is about twelve hundred million sperm per millilitre. Many Livestock Improvement AB technicians have carried out more than 100,000 inseminations in their career. 16

17 GLOSSARY Abnormalities unwanted or undesirable features Analyse to look at, to identify, to assess. Artificial breeding the term used to describe the process of inseminating a female animal with semen for conception. Artificial vagina the device used by Livestock Improvement to collect semen from artificial breeding bulls. Breed The type of animal eg Holstein Friesian (black and white), Jersey (brown), Ayrshire (red and white) Breeding Worth An index used to indicate the genetic potential of an animal to earn profit for its owner. Calving the term used when cows give birth Capacity when applied to the udder refers to the cow s ability to produce and store milk. Castration an operation which removes the testicles from an entire male animal. Cells a single unit of a body surrounded by a membrane, containing DNA and other small organs that help the cell function. Centre Status The state of health that a bull must be in to be able to be used for artificial breeding. Cervix part of the reproductive organ of a cow Characteristics things that make something unique. CHEQMATE nominated semen - the brand name for nominated semen supplied by Livestock Improvement. Collection barn The barn where bulls are taken for semen collection Commercial herd a herd of cows which is milked; the sale of the milk produces income for its owner Conception when a sperm and ovum combine to produce a pregnancy. Conformation physical shape of an animal Crossbred/crossbreed a combination of two or more breeds eg Holstein Friesian x Jersey. Cryogenic very low temperature freezing. Cull an animal which has past its productive life and is sent for slaughter Database Livestock Improvement s database of dairy cow ancestry, production and mating statistics. Degrees Celsius a measure of temperature Diluent a solution used to dilute the concentration of a liquid Efficient cows cows which convert grass to milk and which conceive and calve each year. Ejaculate a collection of sperm Elite sire the best of the best Export to sell overseas Fertility The ability to conceive/be fertile. 17

18 Forage an animal s ability to search for grass. Foreign when this applies to the area of health it relates to something outside the normally accepted area. Genetic defects inherited traits which can cause problems Genetic gain - the result of breeding increasingly superior bulls to increasingly superior cows and can be measured by the increased milk production of these cows year on year). Hay grass cut during spring and stored (and dried) in bails. Usually fed during winter, when cows are not being milked, and when grass supply is decreased to maintain their body weight. Heifers young female cows which have yet to have a calf Herd improvement various measures which contribute to increased production from commercial dairy herds. Herd recording collection of statistics which relate to various aspects of milk production (eg mating, milk production, disease) Herd tests the milk samples which are taken periodically to tell a farmer how good an individual cow is Inbreeding when two closely-related animals breed In-calf term used when a cow is pregnant Index A comparative measure. Insemination The process of putting semen into a cows uterus to cause pregnancy. Liquid nitrogen Super cold (-196 degrees C) liquefied gas. Liveweight the weight of an animal. Mating the act of bringing a sperm together with an egg to produce an embryo, and ultimately a calf. Milk solids combined fat and protein yield of milk. Milk volume the amount of milk produced. Millilitre One thousandth of a litre. Mounting The act of an animal raising its front legs onto the back of another animal in preparation for mating or before ejaculation. National herd the total herd of all dairy cows in New Zealand Nominated semen - Livestock Improvement s artificial breeding option, Cheqmate and Globull, which allows farmers to choose which specific sires they want to use in their herd and on specific cows. Offspring the young of an animal Ovaries Female reproductive organs that produce eggs. Overhead wires Wires that run above a paddock onto which a bull is attached by a chain for free grazing Oxygen the reactive gas that makes up 20% of the air we breathe Paddock an area of grass surrounded by fences, may also be called a field. Pastoral farming grass based. Penis male reproductive organ Percentage Part of a whole amount 18

19 Premier Sires Livestock Improvement s team of elite bulls Productivity ability to produce (in the case of a cow) milk Progeny tested a programme which generates daughters of promising young bulls that are milked and tested for milk production and a number of other traits. Race A track between paddocks Receptive - willing to receive, accepting. Regulations rules to be followed Semen the male reproductive fluid containing sperm Silage grass cut during spring and stored in large covered stacks. Fed to stock when there is not a good supply of fresh grass. Sire - father Sire Proving Scheme Livestock Improvement s programme to progeny test bulls Sperm the mature male sex cell of an animal by which the ovum is fertilised. Static without motion Steer A vasectomised or castrated bull Stock livestock Straws of semen fine plastic straws used to store semen Supplementary feed food (silage and/or hay) fed to supplement a grass-based diet. Teaser castrated or vasectomised steer used to tease, or sexually excite, artificial breeding bulls so semen can be collected. Test tube A small glass tube used to hold liquid Testes Male testicles/reproductive organs Tethering to tie up or attach to Thaw to warm; to change from frozen to liquid state. Trait A specific feature. Trial A test Vasectomy surgical cutting and sealing of part of male vas deferens to sterilise. Yearlings animals that are between 12 and 24 months of age 19

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