Breeding and genetics
In recent years there has been a rapid increase in genetic merit in UK dairy herds. This rapid increase has largely been attributed to the importation of semen from North America and Europe, coupled with advances in progeny testing schemes and the introduction of advanced techniques to evaluate progeny test data from different countries.
Top sires in Northern Ireland ranked on Profitable Lifetime Index (£PLI)
DairyCo Breeding+ conduct independent sire evaluations for the various dairy breeds in the UK three times per year. Full sire listings for all breeds are available by the DairyCo website and then the link for the appropriate breed.
Sires of each breed are ranked on Profitable Lifetime Index (£PLI) which is a total merit index that takes account of the PTAs for a number of productive and non-productive traits. Those with the highest £PLI generally have a combination of reasonable yield and milk quality whilst also having favourable PTAs for fertility, lifespan and milk quality. The August 2014 proof run by DairyCo saw two major changes to £PLI. Firstly there was a base change which occurs every five years to reflect changes in genetics of the various breeds. This led to changes in the PTAs of individual traits for all bulls listed. Secondly the economic weighting of the various traits changed placing more emphasis on the functional or non-productive traits with the result the £PLI of the highest ranking Holstein bulls has risen from around £250 to over £600.
August 2014 also saw the launch of the new Spring Calving Index (£SCI). This is an across breed evaluation with bulls from various breeds listed on the one genetic base. This index places much more emphasis on the non-productive traits and is recommended for spring calving herds only. Everyone else should use the £PLI index for the appropriate breed.
CAFRE have summarised the various DairyCo proofs lists as follows, where appropriate listing the top 100 sires available in Northern Ireland.
Suppliers of semen in these lists are based on the information made available from DairyCo for which CAFRE cannot accept responsibility.
Profitable Lifetime index (£PLI) is the primary selection index used for ranking dairy cattle in the UK. It is based on a series of production traits (milk, butterfat and protein yield) making up 45 percent of the index, and non-production traits such as fertility, locomotion, somatic cell count and lifespan accounting for the remaining 55 percent. CAFRE have developed a short course on what £PLI means and how best to select AI sires using £PLI.
DairyCo Breeding+ produce herd genetic reports for milk recorded and pedigree registered herds that are also available from your milk recorder. If you know the average genetic merit of your herd and have clear breeding aims in mind, a herd genetic summary can be used to aid sire selection. CAFRE have developed a short course demonstrating how the herd genetic summary is used to aid sire selection in Greenmount’s Future Herd.
Genetic codes explained
In the sire lists produced by DairyCo and breed societies, sire names are followed by various genetic codes. These are summarised by clicking on the link below.
| Code | Condition |
|---|---|
| BD | Bulldog |
| BL | Bovine Leukocyte Adhesion Deficiency (BLAD) |
| TL | Tested free of BLAD |
| CV | Complex Vertebal Malformation (CVM) |
| TV | Tested free of CVM |
| DF | Dwarfism |
| DP | Defficiency of Uridine Monophosphate Synthase (DUMPS) |
| TD | Tested free of DUMPS |
| HL | Hairless |
| IS | Imperfect skin |
| MF | Mule-foot |
| TM | Tested free of mule-foot |
| PO | Polled |
| PG | Prolonged gestation |
| PT | Pink tooth (porphyria) |
| RC | Carrier of red hair |
| B/R | Black/red |
| TR | Tested free of red hair colour |
Lifetime Performance of Dairy Cows in Northern Ireland
One of the targets of Greenmount’s Future Herd is an average lifetime yield of 40,000 litres per cow. A technology investigation was conducted in collaboration with United Dairy Farmers and Holstein UK which established that the Northern Ireland lifetime yield average is around 27,000 litres though there was considerable variation between herds.
Impact of sire Fertility PTA on daughter fertility
Sire Fertility Index was developed by scientists at the University of Edinburgh and Scottish Agricultural College with the aim of improving dairy cow fertility through breeding from more fertile bulls. Each one-point increase in a sire’s Fertility Index should increase daughters conception rate by 0.5 percent and decrease daughter calving index by 0.5 days, but analysis of breeding records from Greenmount’s Future Herd show that the benefits are even greater.
Potential benefits of sexed semen
Sexed semen has been commercially available to farmers in the UK since 2000. Due to the sorting process, there are fewer sperm cells in each straw than conventional semen and conception rates are generally expected to be around 10 percent lower. Therefore sexed semen is generally only recommended for use on maiden heifers. The benefits of using sexed semen include more rapid genetic progress and increased number of heifer calves allowing more cows to be served with beef semen.
Impact of Complex Vertebral Malformation (CVM) on dairy cows fertility
CVM is a genetic condition in Holstein cattle that leads to embryonic loss and abortion. It is only a problem when two CVM carrier animals are mated and was first discovered in 2000 when the effects of a carrier sire, Carlin-M Ivanhoe Bell, became apparent. At Greenmount, genetic testing of cows descended from CVM carrier bulls were tested for CVM and breeding records analysed. Sires are now selected that are tested free of CVM (*TV).
Impact of Complex Vertebral Malformation (CVM) on dairy cows fertility
More useful links
Useful links to top UK available sires (DairyCo) and milk recording companies (dairy herd management NMR) for the download of your herd genetic report.