Breeding poll cattle: the alternative to dehorning

Transcription

1 Breeding poll cattle: the alternative to dehorning John Henshall Group Leader, Genetics Genomics 10 May 2012 CSIRO LIVESTOCK INDUSTRIES

2 Horns Undesirable bruising hide damage injury to the animal to other cattle and to humans

3 Dehorning Routine Dairy Very young (disbudding) Intensive Beef Young calves Extensive Beef Older calves

4 Dehorning Routine Dairy Very young (disbudding) Intensive Beef Young calves Extensive Beef Older calves More labour intensive More pain Wounds take longer to heal More risk of secondary infections Higher mortality

5 Dehorning Routine Dairy Very young (disbudding) Intensive Beef Young calves Extensive Beef Older calves More labour intensive More pain Wounds take longer to heal More risk of secondary infections Higher mortality Significant Welfare Issue

6 Polled Been around for years No need to dehorn Reduced labour cost No pain No wounds No secondary infections No mortality

7 Polled Been around for years No need to dehorn Reduced labour cost No pain No wounds No secondary infections No mortality So why aren t all cattle polled?

8 Issues with Polled Tradition Perception of reduced performance Lack of suitable genetics Time required to change herd

9 Issues with Polled Tradition Perception of reduced performance Lack of suitable genetics Time required to change herd

10 First genetics of polled Basically under control of a single region on the genome In Bos taurus, polled is dominant Inheriting a polled allele from either parent is enough to make an animal polled In B. indicus derived breeds less clear cut Heterozygous animals (those with a polled allele from one parent and a horned allele from the other parent) often have scurs, and sometimes horns Still much we don t know

11 Perception of Reduced Performance Two ways this could happen 1. The mutation responsible for polled also affects other traits, or causes genetic abnormalities

12 Perception of Reduced Performance Two ways this could happen 1. The mutation responsible for polled also affects other traits, or causes genetic abnormalities No evidence that this is the case in Australian beef cattle

13 Perception of Reduced Performance Two ways this could happen 1. The mutation responsible for polled also affects other traits, or causes genetic abnormalities No evidence that this is the case in Australian beef cattle 2. In a breed where polled is uncommon, polled animals may be closely related, and therefore be similar for other traits

14 Perception of Reduced Performance Two ways this could happen 1. The mutation responsible for polled also affects other traits, or causes genetic abnormalities No evidence that this is the case in Australian beef cattle 2. In a breed where polled is uncommon, polled animals may be closely related, and therefore be similar for other traits The polled genetics on offer may be different from the genetics of the herd, and may not suit the environment or production system

15 Lack of Suitable Genetics In a breed where polled is uncommon, polled animals may be closely related, and therefore be similar for other traits The polled genetics on offer may be different from the genetics of the herd, and may not suit the environment or production system Demand - Bulls that otherwise wouldn t be on the market might be, just because they are polled Single trait selection is almost always bad Even if polled bulls that are good for other traits are available, they may be too expensive

16 Time required to change herd To eliminate horned alleles from the herd could take 30 years To eliminate dehorning could be much quicker though In B. taurus a polled allele from one parent is enough B. indicus, there will still be some horns and scurs Crossbred cattle? This is one of the things we don t fully know the answer to

17 Time required to change herd Thirty years is too long, to speed things up: Need to know the poll status of bulls A polled bull might carry two copies of the polled allele, or one polled allele and one horned allele If he carries a horned allele he will pass it on to 50% of his progeny, if the cow herd is polled some of the calves may be scurred, and in B. indicus some may be horned If the cow herd is horned then half of the bull s progeny will be horned You can do a progeny test, but you won t know the answer for a year The alternative is to use a gene marker test

18 Gene tests for polled Tests developed for B. taurus are available, but not validated in breeds with B. indicus content The Beef CRC test was developed in Australian Brahmans, but also works well in other breeds Commercialised by two providers Not perfect Can discriminate between animals with one polled allele or two polled alleles 90% of the time in some breeds, but only 50% of the time in others Even then, there is some uncertainty, there might be a 1 in 10 chance that the test is wrong similar to a progeny test with 5 calves

19 Improving the test Use pedigree information Within herd by hand Through your breed society (soon) The current test uses a single microsatellite marker. We have a pilot study with additional markers added Very promising results (~400 animals, inconsistencies could be explained by 3 miss-calls for horned vs polled) Works well in all breeds tested Validation trial planned (~2,000 animals)

20 Acknowledgements Current Polled Test Kishore Prayaga Maxy Mariasegaram Emily Piper (validation) Combining Pedigree Information and Optimisation of the test Bruce Tier New Test with Additional Markers Emily Piper Funding MLA Data Many Breeders and Breed Societies

21 Thank you CSIRO Livestock Industries John Henshall john.henshall@csiro.au CSIRO LIVESTOCK INDUSTRIES