Watch: selective breeding for the optimal cow

There is no such thing as the perfect cow to suit all types of dairying systems. However, within individual farms there should be the aim to breed a cow that delivers optimal performance from the farm system.

This cow will meet a list of criteria which varies between individual farms. As a starting point, most farmers want a cow that calves down when she should, produces milk, goes back in calf each year and has no health issues.

Autumn-calving herds on the Dairylink Ireland programme are currently selecting sires for breeding, which is due to start next month.

This gives the opportunity to capitalise on existing traits within a herd and address shortfalls by being selective in what sires are used on specific cows.

The aim is to push the genetics of progeny towards the optimal cow.

At the two Dairylink Ireland farm walks last week, Nigel Corbett and Robin Clements set out what they want to achieve from their herds.

Both farmers have fairly similar aims, such as they want a cow that calves between September and November with a 370-day calving interval or less.

They want a yield of 7,500 litres at 4.35% butterfat and 3.50% protein, with 4,000 litres from forage.

Both farmers are continuing to tighten calving profiles, which can mean some hard decisions have to made, such as selling, culling or not breeding replacements from cows that are calving outside the window.

Dairylink adviser Conail Keown says that improving fertility is the main benefit from developing a compact profile, as cows that are slow to get back in calf are not bred from and are culled.

Compact calving also means many tasks become seasonal and labour can fully focus on calving, breeding and calf rearing at certain times of the year.

Individual cows are being assessed on Robin’s and Nigel’s farms to see how selective breeding can be used to develop the optimal cow for each of their farm systems.

Examples of cows assessed during last week’s farm walks are outlined below.

Cow 1993

This fifth-lactation cow is a Holstein Jersey crossbred. She yielded 7,475 litres in her last lactation at 6.0% butterfat and 3.8% protein. She weighs 525kg and produced 755kg of milk solids last lactation.

This cow calved in October this year, with a calving interval of 372 days. She has had no health issues and although she has a low body condition score of 2.25 at present, it is to be expected at her stage in lactation and with her Jersey genetics.

It is difficult to find fault with this cow, so she will probably be bred with a black and white sire with low positive sub-indexes for fertility and production to improve her genetics further.

Between eight to 10 sires will be selected for use in the herd. Six have been selected so far and have an average EBI of €241 with a fertility sub-index of €124, +64kg for milk, +12kg for butterfat and +8.4kg for protein.

Cow 1930

This fifth-lactation Holstein cow weighs 700kg and yielded 10,950 litres during her last lactation at 3.5% butterfat and 3.3% protein. She last calved in December 2016 and is due to calve in February 2018 to the Aberdeen Angus stock bull with a 421-day calving interval.

This cow will probably be sold off this winter, as she is calving outside the autumn window and will be producing a low volume of milk during the high-cost winter feeding period.

Although she is heavier than my ideal cow body weight of 600kg and has lower butterfat and protein than I would ideally like, I would keep her in the herd if she was calving at the right time.

Breeding from late calvers like her every year will not help develop a compact calving profile. An option is to keep some late calvers and keep using a stock bull, as they will eventually fall out of the herd as they get older.

Cow 2021

This second-lactation cow calved at the end of September and is currently yielding 30 litres. In her first lactation, she yielded 9,324 litres at 3.72% butterfat and 2.88% protein.

She has a 351-day calving interval and is calving at the right time of year for my system. She weighs 558kg and will grow a bit more this lactation, but should have a mature body weight around 600kg, which is what I am after.

This cow is producing plenty of litres, but her milk components are lower than the ideal 4.35% butterfat and 3.5% protein. I have not finalised any bulls yet, but this cow will be bred with a black and white bull with high breeding indexes for butterfat and protein and a negative index for milk. An option being considered is to crossbreed with Jersey, although this could be better suited to some of my larger cows to reduce body weight while increasing milk solids.

Cow 637

This cow is fertile with a 368-day calving interval, but is falling outside the autumn-calving system. She is due to calve down in April and is currently yielding 23 litres.

She yielded 9,203 litres last lactation at 3.93% butterfat and 3.05% protein. She is a fifth-lactation cow and weighs 690kg.

There are no major faults with this cow, other than she is calving at the wrong time. It will be too costly to delay breeding to bring her into the autumn-calving profile.

An option is to sell late-calving cows like this and replace them with bought-in autumn-calving cows.

Sires selected for milk solids and fertility will be used on most cows that are calving at the correct time to increase average butterfat and protein from 4.12% and 3.4% and reduce herd calving index from 391 days.