The global Holstein\npopulation has become more inbred over time, increasing at about 0.1% per year.\nThis is causing increased inbreeding depression, especially for mortality, cow\nfertility, cow health and survival. As relationships between individuals rise, it\nbecomes more and more likely that bulls and cows that are mated to each other\nwill be closely related. Unfortunately the use of genomically selected sires\nappears to be increasing inbreeding in some dairy breeds.<\/p>\n\n\n\n
Inbreeding robs dairy\nproducers of income by increasing stillbirths, meanwhile reducing cow\nfertility, disease resistance and shortening herd life. As highly inbred\nembryos are not viable, this leads to a reduction in cow fertility.<\/p>\n\n\n\n
Why crossbreeding?<\/strong><\/p>\n\n\n\n Crossbreeding eliminates\nconcerns about inbreeding. When breeds for a crossbreeding scheme are chosen\nwell, the effects of heterosis are the opposite of the effects of inbreeding\ndepression. Heterosis will be an additional benefit on top of the parent\n(breed) advantage and is especially valuable for traits such as vitality,\nfertility, disease resistance and health.<\/p>\n\n\n\n Effective crossbreeding\nbegins with two superior breeds. These breeds must complement each other well\nand independently have a large enough selection base to continue their own\nunique breeding goals. Bringing together two breeds with desirable genes is\ncalled complementarity. A crossbreeding program should be well planned and\norganized and use the best bulls from breeds that suit your dairy farm\nconditions.<\/p>\n\n\n\n Number of breeds to use\nin dairy crossbreeding systems<\/strong><\/p>\n\n\n\n The extent of heterosis\nrealized from crossbreeding systems differs based on the number of breeds\nincluded in the rotation. Table 1 shows the extent of heterosis realized for\neach generation in crossbreeding systems that include 2, 3, or 4 unrelated\nbreeds. Generally speaking, finding more than three breeds that are especially\nwell-suited for a specific environment or management system may be difficult.<\/p>\n\n\n\n Table 1.<\/strong> Heterosis by generation for crossbreeding using 2, 3 or 4 unrelated breeds in rotation. <\/p>\n\n\n\n 2 PLUS\u2122 is a rotational crossbreeding\nsystem using two breeds, for example whereby the Holstein and the Norwegian Red\n(NRF) breeds are used alternately to produce the next generation. Thus F1*\nheifers from NRF sires should be mated to purebred Holstein bulls; their\nprogeny to NRF; the progeny of those to Holstein; and so on. Read "How Many and Which Breeds to Use"<\/strong><\/a> for assistance in\nchoosing the best breeds and 2-, 3- or 4-breed rotational crossbreeding scheme\nthat will benefit you the most. <\/p>\n\n\n\n Use highly ranked progeny\ntested bulls<\/strong><\/p>\n\n\n\n Crossbreeding "done\nwell" can be viewed as a mating system that exploits and goes beyond the\ngenetic improvement happening within breeds. Continuous use of progeny-tested\nand highly-ranked A.I. bulls is critical to genetic improvement regardless of\nthe mating system (pure breeding or crossbreeding). Use of the best A.I. bulls\nfrom each breed in your crossbreeding scheme, chosen according to your breeding\ngoals, will give you the best results.<\/p>\n\n\n\n Unfortunately some dairy\nproducers might interpret the benefits of crossbreeding as justification to use\nnatural service "different breed" bulls rather than A.I. This\npractice results in lower merit offspring the majority of the time.<\/p>\n\n\n\n Norwegian Red for health\nand fertility<\/strong><\/p>\n\n\n\n The Norwegian Red is a\nhigh producing dairy cow that has been selected for health and fertility traits\nfor the past 40 years. Several international trials<\/strong><\/a> prove that the\nNorwegian Red breed is superior for health and fertility and is a profitable\nbreed choice for a well-designed crossbreeding scheme.<\/p>\n\n\n\n![\"\"](\"https:\/\/crossbreeding.co.il\/wp-content\/uploads\/2023\/03\/TABLE_GENERATION_PERCENT-1.png\")
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