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Wednesday 20 September 2017

Don't let silage distract you from the late calving cows says top vet

 

Eamon O'Connell
Eamon O'Connell

Eamon O'Connell

It is a very busy time on most dairy farms at present. Heat detection and AI are at the forefront of everyone's mind and the calving season is already long forgotten about. However, in small paddocks all around the country, there are a few cows still left to calve. These are what I like to refer to as "the forgotten cows".

AI, silage, fertiliser and fencing are just some of the jobs that take priority over these cows. A quick glance is all that they are given or, all too often, they only pop into the mind at 10pm or 11pm at night when the pressure of a busy day is off.

"I had nowhere for the bull, so I left him with the cows" or "she's a great cow and I didn't want to get rid of her". These are the common excuses given when I ask why cows are calving so late. The unfortunate reality of these cows is that every day you spend watching and wondering if they are ever going to calve is costing you money.

These late calving cows come with a myriad of problems. Often dry for nearly six months, they are closer to being "fit to kill" than "fit to calve".

They are not on a proper dry cow diet and the pre-calving mineral application can be hit and miss at best. Because of this, they have a much higher incidence of calving difficulty, milk fever, retained placenta or ketosis. Not to mention that, in comparison to a cow that calved on February 1, they are now up to four months behind on milk production. In short, they have no place in the modern spring -calving dairy system.

So, how do we go about making sure that we don't have these cows in the herd this time next year?

Cows late calving
Cows late calving

Firstly, we need to make sure that cows come bulling at the right time. Heat detection aids such as tail paint and a vasectomised bull greatly increase submission rates in herds where AI is used. In farms that rely solely on bulls, it is vital that a bull breeding soundness exam is carried out by your vet on every bull. Most farms have now up to four weeks of breeding completed. Any cow that has not presented for breeding by now should be scanned by your vet immediately. Problems such as cysts or metritis can be identified and treated which greatly increases the chances of a cow calving in March rather than in May next year.

The general health of each individual cow directly influences her ability to come bulling and subsequently go in calf. The mineral status of the herd is very important. A deficiency in minerals such as Copper, Iodine, Selenium or Phosphorus has a direct effect on fertility. Diseases such as IBR, BVD and lepto cause early embryo death in dairy herds across the country. If a cow in the very early stages of pregnancy comes in contact with one of these agents, it can end her pregnancy. Often, the only visible sign will be that a cow that hasn't been seen bulling in the previous 6-8 weeks, will suddenly be seen bulling again. In reality, any condition that causes a high temperature can cause early embryo death. Mastitis can have a negative effect on fertility too.

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The recent dry spell has meant that, in many parts of the country, cows were grazing low grass covers which led to a subsequent drop in milk fat percentage. Low milk fat is an indicator of SARA (sub acute rumen acidosis). This has a negative effect on fertility. Similarly, low milk protein percentage is an indicator of NEB (negative energy balance) which too has a negative effect on fertility.

Management of heifers is very important. It is vital that a heifer calves in February. If a heifer has her first calf in April, then she is already on the back foot. It is unrealistic to expect her to calve in February for her second lactation.

A detailed herd monitoring and action plan should be put in place immediately to ensure that cows are presented for bulling as early as possible and therefore calve down next year at the right time. Unfortunately, some difficult decisions will have to be made. The "great" cow may ultimately have to be culled. In modern dairy farming, where margins are getting tighter, the old adage "Any day a cow calves is a good day" is no longer true.

Planning for better fertility

• Bulk milk sample: Tests for BVD, Lepto and IBR. Also a good guide to levels of fluke and worms.

• Blood samples: 10 cows. It important to take a good cross section. Include some first and second calvers. Use in combination with soil and forage analysis to give a very accurate picture of any mineral deficiencies.

• Milk recording data: The protein and butter fat of each individual cow should be examined. Ketosis and SARA can be identified and treated before a fertility problem arises.

• Accurate records: This doesn't only pertain to recording heats. Any cases of milk fever, mastitis or difficult calvings should be recorded. These cows can be singled out for attention at the start of the breeding season.

• Management of first calvers: When a first calving heifer nears calving, her immune system comes under considerable stress, leaving her considerably more susceptible to infections such as mastitis and metritis. This, in turn, can have a negative effect on fertility (not to mention milk yield). It is important to make every effort to minimize this.

• Aggressive culling: Don't be afraid to cull the late calvers. If she calves in May or June, then she is not your "best" cow.

• Lameness: If a cow is lame, she will spend significantly less time showing signs of standing heat. She may not even stand to be served by the bull. Treating lame cows in the early stage at this time of year will significantly help their fertility.

• Nutrition: A cow needs energy to milk and to go in calf. Use all the data, the knowledge and expertise that is available to you. Your nutritionist, your advisor and your vet can all offer excellent advice on nutrition. All groups should consult with each other to come up with the best nutritional advice for each individual farm.

Eamon O'Connell is a vet based at Summerhill Veterinary Clinic, Nenagh, Co Tipperary


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