Farm Ireland
Independent.ie

Saturday 16 December 2017

Common sense will be needed if crossbreeding is to work here

Dairy

Dr Dan Ryan

Over the past month, many spring calving dairy cows have been dried off. The impact of an impending superlevy has resulted in cows being dried off early, empty cows being culled and a decision made to shut down milk production until February.

I have always said that a breeding programme begins from the time a cow is dried off. The primary focus should be a target body condition score at the time cows are dried off.

Integral to any breeding programme are the sires to be used on the dairy herd. More than 90pc of sires used on spring calving dairy cows are Holstein Friesian.

Based on some reports, there is a belief that a considerably lower proportion of Holstein Friesian sires are being used in favour of more crossbreeding with Jersey, Norwegian Red, Brown Swiss, Montbeliarde and Ayrshire.

This is not just a trend in grass-based milk production in Ireland. American and Canadian studies show an increased use of crossbreeding in large dairy herds homed indoors.

In a 3,000-cow herd in South Dakota, Jersey, Norwegian Red and Fleckvieh sires are used to produce crossbred progeny for the dairy herd in a four-way crossbreeding programme. They avoid the birth of Jersey crosses in the harsh winter months because of poor survival rates. This farmer claims that the health status and thereby reproductive performance of the herd has improved.

Crossbreeding will enhance hybrid vigour in the dairy herd. The primary benefits are enhanced milk components and reproductive performance. But crossbreeding programmes are long-term decisions.

Performance of the first crosses will display full hybrid vigour and will result in uniform animals. But the first cross then has to be bred to a third breed or a backcross to the parent breed. About half of the hybrid vigour will be lost with a backcross when compared with the first generation crosses.

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The creation of a combination of purebreds and cows from two and three breed crosses will create management complications in terms of size and age at sexual maturity. Examples include the delayed onset of heat cycles in the Montbeliarde X Friesian maiden heifers, the small Jersey X Holstein cows in terms of cubicle size and milking parlour space.

Three breed rotational systems utilising AI-proven purebred sires are the best approach in a crossbreeding programme. At equilibrium, the three breed crossbreeds maintain 86pc of full hybrid vigour. They can also reduce the large differences encountered in terms of rate of maturity, mature body size and milk components seen from one generation to the next when compared with two breed rotational crosses. Only 67pc of full hybrid vigor is maintained in two-breed rotational systems.

Why have we resorted to use of crossbreeding? The primary reason has been a frustration with poor reproductive performance in the Holstein cow on grass-based milk production systems. Inbreeding levels have increased in purebred dairy populations. Fertility has subsequently decreased in dairy herds in response to selection for higher yields and/or inbreeding depression.

In our quest for cost-efficient milk production from grazed grass, the traditional Holstein cow has become a square peg in a round hole. The window of opportunity to achieve a 90pc calving rate in 11 weeks is too narrow for the Holstein herd. In reality, 90pc calving rates are only achieved with 15-20-week breeding periods.

Common sense is needed if crossbreeding is going to work successfully in this country. This is not New Zealand. We need our own management model for grass-based milk production.

Body condition score management at various stages of the production cycle needs to be correct. Semi-starvation of cows in the dry-cow and early post-calving periods with a view to compensatory gain immediately prior to the breeding season is not viable.

In my opinion, under-feeding and overcrowding cows in a poor environment are the greatest cause of impaired reproductive performance in the Irish dairy industry.

Major improvements have been made in various production traits within the Holstein breed using the EBI. Indeed, about half the hybrid vigour achieved from crossbreeding can be achieved by crossing Holstein with British and Dutch Friesian.

Finally, the beef industry is very dependent on progeny from the dairy industry. Crossbred Jersey bull calves and Jersey cull cows do not fit into cost efficient beef production systems.

In conclusion, crossbreeding may well have a place in cost-efficient grass-based milk production. But improvement in genetic selection and avoidance of inbreeding within the Holstein breed may achieve the same goal.

Dr Dan Ryan is a breeding management consultant and can be contacted on www.cows356.com

Indo Farming