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Breeding Heifers For Profit

30 April 2011

The anticipated expansion in milk production, following the removal of EU Milk Quotas in 2015, will not be achieved without adequate numbers of AI bred, high EBI, early born and well-reared replacement heifers. Now is the time to start breeding the dairy herd for milk production after milk quotas. Breeding decisions taken in 2011 will result in heifers entering the herd in 2014, provided they are reared to calve at 24 months, writes Tom O'Dwyer, Head of Dairy Knowledge Transfer at Teagasc.

Quality of replacement heifers

There are four legs to the stool which support dairy herd fertility:

  1. Nutrition
  2. Health
  3. Genetics
  4. Mating Management

Should any of these legs fail – herd fertility will suffer. Nationally, herd fertility is below optimum with the proportion of April/June calving cows increasing from 23 per cent to 34 per cent in the mid 2000’s. In addition replacement rate is 27 per cent. This is costing farmers’ money - extra cost to rear these replacements, expansion is curtailed and herd milk yield is reduced as heifers are a high proportion of the herd. In addition, late calving cows are adding to seasonal peak of milk supply for the processing sector.

Quality of Heifers

One weakness in tackling herd fertility is genetics. Nationally fertility sub-index in the EBI is €29, but is even lower in the northern counties which have an average fertility sub-index (SI) of only €21.

The target is to produce heifers with a €70 fertility sub-index (in their EBI) from breeding decision you make this spring. To achieve this – you need to select a team of bulls which are at least €100 of fertility sub-index.

e.g., €40 cow fertility SI + €100 bull fertility SI = €70 Daughter fertility SI

Data from ICBF now clearly shows that the higher the fertility sub-index of a herd, the greater the survival of cows from lactation to lactation.

Selecting bulls

The following are the four key steps you must follow this spring to produce heifer calves with fertility sub-index of €70.

  1. Use AI only. AI bulls have reliable information on fertility that a stock bull will never have.
  2. Use high EBI bulls ( average €200) – these bring a good balance of fertility and milk.
  3. Use a team of bulls from the ICBF active bull list.
  4. Team of bulls should have at least €100 fertility sub-index.

You can also improve another trait in your heifers, e.g. protein per cent, but adhere to the above points above to improve fertility.

Heat Detection

Each missed heat is a future loss of €250 profit. High 21 day submission rates are the first step to keeping the calving compact and giving all cows at least three opportunities to get back in calf.

Over 70 per cent of cows come into heat between 7.00 p.m. and 9.00 a.m. On average each heat lasts for 3 hours (range 3-30 hours). This is a very short window of opportunity to identify cows. Also, as the number of cows in heat in the herd decreases, so too does the mounting activity. Therefore, after the first three weeks of breeding, identifying cows becomes more difficult.

Farms that are successfully using 100 per cent AI are not relying totally on observation to identify cows in heat. They are using one or two heat detection aids to help identify cows in heat – so that they can be artificially inseminated with high EBI sires.

Tail Paint:This is a cheap, easy to apply system. A narrow strip (9 inches x 2 inches) is painted on the tail head. When the cow is mounted – the paint is broken away. The paint needs to be replenished every 3-4 days. Research has shown that if 25 per cent of the paint is removed – there is a 76 per cent chance she is bulling. If 100 per cent of paint is removed – there is a 93 per cent chance the cow is bulling.

Paint-Sticks: These operate similar to tail paint.

Scratch Cards: They contain an adhesive which sticks a scratch pad to the cow. When the cow is mounted – the colour is revealed.

Dyes pads: These are stuck onto the cow and the dye colour is made visible when the cow is mounted.

Automated Heat Detection:These operate on the basis that a cow in heat has more activity compared to cows not in heat. A neckband / pedometer is fitted on each cow monitors to monitor cow activity.

Vasectomised Bull plus Chinball Harness: A young bull can be vasectomised and run with the herd. A chinball will mark each cow that the bull mounts.

On farm trial: Four heat detection aids were trialled on seven commercial dairy farms by Teagasc Moorepark. They were tail-painted, paint-stick, scratch card and dye pad. There was no difference in three weeks submission rates and pregnancy rates with the four products. When the farmers were asked about overall performance for the four products – they identified tail paint as the most preferred method.

Quantity of Heifers

Sufficient heifers are needed for normal replacement rate, planned expansion and the option to sell surplus heifers. This region needs to increase the number of heifers reared per 100 cows to satisfy there requirements. While data from the National Farm Survey show that 90 per cent dairy farms are using AI – the same data shows that not enough dairy replacement inseminations are being used. It takes approximately 5.5 straws to generate one milking heifer. Remember, half will repeat and half will be males before any losses are incurred.

Therefore, if you want 30 milking heifers in 2014, you need to use minimum of 165 straws this spring.

Synchronisation for Heifers

Well grown heifers (330kg HF) can be synchronised for breeding during April. The benefit is that they will calve compactly at the start of calving season and can produce early born heifer calves.

Prostaglandin synchronisation protocols work very well for heifers, but will not work in non-cycling heifers. The following protocol works:

  1. Tail paint all heifers and inseminate following observation of oestrus during the first 6 days of the breeding season.
  2. All heifers not inseminated in the first 6 days receive a prostaglandin injecting on day 7 and are inseminated following observation of oestrus in the next 3 -5 days.
  3. Heifers that failed to come into heat following the first injection of prostaglandin receive a second injection 10 days later.
  4. Heifers are again inseminated at a standing heat, or receive fixed time AI at 72 and 96h after the second injection.

This protocol should result in 100 per cent submission rate and 70 per cent conception to first service.

Heifer Rearing

Data from ICBF show that of the dairy heifer calves born in 2007, only 48 per cent of these calved between 22 – 26 months of age. By 36 months only 73 per cent had calved. This suggested that a lot of calves do not reach target weights. This is a major cost to dairy farmers. The key target weight for calving at two years of age is mating weight. For Friesians, this should be 330kg, which is usually in mid-April for Spring-born herds. These heifers should calve at 550kg. This is equivalent to an average daily gain of 0.7kg / day over two years. Heifers born a month later must gain closer to 0.75kg. There is no space for a store period when rearing heifers. The first year is crucial.

A crucial factor in heifer rearing is reaching target weight at mating. Heifers must reach 60 per cent of their mature bodyweight by mating to be cycling. Table 1 outlines the key weights. This was further emphasised in the Teagasc Moorepark Fertility Study on commercial dairy farms. Heifers cycling at the start of breeding weighed 326kg, those that were not cycling weighed 296kg. This was only a 30 kg difference.

Table 1

A high rate of gain from birth to calving is essential to achieve there targets. There is no place in heifer rearing for a store period where for a month (or two) heifers put on no weight. Take a 40kg calf in February; she will need to gain 510 kg over two years (730 days) which is 0.7 kg gain over this period. An April-born calf would need to gain 0.75 kg / day over this period.

Heifer Rearing Stages

There are seven distinct stages. Target weights must be reached after each stage. The following is a simple checklist. The approximate weight to be gained is also provided – this is to take a 40 kg calf to 550kg at calving.

Calf rearing (gain 50kg):
  • Adequate colostrum must be fed
  • Diseases/housing issues minimised
  • Calves eating sufficient solid feed at weaning
1st Summer at Grass (gain 100kg):
  • Control programme for worms / hoose
  • Access to leafy grass
  • Calves are selective graziers
  • No restriction on leafy grass
Autumn (gain 40kg):
  • Adequate grass must be provided
  • Adequate meal fed where necessary
1st Winter (gain 50kg):
  • Appropriate housing/feed area available
  • Parasite programme for worms/hoose/fluke
  • Silage quality assessed
  • Appropriate meals fed to match forage quality
Turnout to Breeding: (gain 50kg):
  • Health – vaccination programme
  • Heifers at grass six weeks before breeding i.e. early March
  • grass available since autumn
2nd Summer: (gain 150kg):
  • Sufficient Grass available
  • Quality of grass available
2nd Winter: (gain 80kg):
  • Parasite programme for worms/hoose/fluke
  • Silage quality assessed
  • Appropriate meals fed to match forage quality

It is useful to regularly weigh heifers to monitor performance. It can be a representative sample in a trailer at a weighbridge. Some discussion groups/ farmers are also investing in their own scales to monitor heifer performance.

April 2011

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